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boomer#[email protected] boomer#6877250@none.com is offline
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Default What is the most powerful audio output tube?

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).

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Bitrex Bitrex is offline
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Default What is the most powerful audio output tube?

On 12/08/2016 10:19 AM, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


The output tranny required for 500 watts RMS is going to be a huge piece
of ****-off iron that will probably set you back the better part of a
grand, at least.

500 watts RMS from four tubes will require you to step up way beyond
6L6es and 807s, I think. You're probably going to want to look at
something like RF power triodes or tetrodes, 813s or the GU-13 if you're
okay with going ex-Soviet.

I am not a pro tube guy though so that's just my guess.

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Tauno Voipio Tauno Voipio is offline
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Default What is the most powerful audio output tube?

On 8.12.16 17:19, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).



807 is the transmitting version of 6L6, so it's no wonder that it looks
similar.

For the power level you're after, you may need real transmitting tubes,
e.g. a pair of 3-500Z's. Please understand that the voltages and
currents encountered at those power levels will be lethal in careless
hands.

--

-TV

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Ralph Barone[_3_] Ralph Barone[_3_] is offline
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Default What is the most powerful audio output tube?

wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).



Go big or go home.
http://www.g8wrb.org/tetrodes/

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Baron[_2_] Baron[_2_] is offline
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Default What is the most powerful audio output tube?

prodded the keyboard with:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6
tubes, which I believe is called " push-pull parallel - parallel",
but I'm looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6,
but after careful research, it's almost identical, but with a
different envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel),
from all tubes, .... With four 6L6 tubes in PPP, I can only get
around 120W RMS (per channel).


Have a look for a Trix cinema amplifier, they did one that used a pair
of 813's at around 500 W rms 100 volt line out.

--
Best Regards:
Baron.


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Big Bad Bob Big Bad Bob is offline
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Default What is the most powerful audio output tube?

On 12/08/16 07:19, so wittily quipped:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


you'd probably do well with 6550, or KT88 (or maybe 8417 if you can find
them) - I think you'd need 6 of them for 500W. Output transformer might
be a bit more difficult.

this page shows the 1650W for 280W and 6 to 8 output tubes

http://www.hammondmfg.com/1608.htm

if you're desperate, you could just bridge two of them to get 560W, or
tweek the circuit and use the 8 ohm output on 4 ohms and run the risk of
frying the transformer at some point...



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John Larkin[_2_] John Larkin[_2_] is offline
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


https://dl.dropboxusercontent.com/u/.../Tubes/833.jpg


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

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Default What is the most powerful audio output tube?

On Thu, 8 Dec 2016 10:39:35 -0500, bitrex
wrote:

On 12/08/2016 10:19 AM, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


The output tranny required for 500 watts RMS is going to be a huge piece
of ****-off iron that will probably set you back the better part of a
grand, at least.

500 watts RMS from four tubes will require you to step up way beyond
6L6es and 807s, I think. You're probably going to want to look at
something like RF power triodes or tetrodes, 813s or the GU-13 if you're
okay with going ex-Soviet.

I am not a pro tube guy though so that's just my guess.


The transformer is the problem, especially if you go with a giant
transmitting tube that runs at high plate voltages.

There have been transformerless audio power amps, using that beast
low-mu triode tube, the one Tek used in their B+ regulators.

Why not use mosfets? Toobs are silly.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

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Peter Wieck Peter Wieck is offline
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Default What is the most powerful audio output tube?

On Thursday, December 8, 2016 at 10:20:48 AM UTC-5, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?


Unless you want to go into the esoteric and include commercial level transmitting tubes, stick with the established types. Leaving you with the KT88/6550/KT90 family of tubes, probably eight of them in PP to get anywhere near 500 watts and within a comfortable operating range for the tubes. 813s will be operating at 2,500 V on the plates, or thereabout. You would only need four of these.

I expect you will be winding your own transformers. For, if you "pay the man" for them, and unless you go to Piltron for a custom wind (their 400W toroidal OPT is considerably over US$400) you are not going to find any off-the-shelf devices in the 500 W range

Or, for the price of one single 400W off the shelf OPT, you could go "Class D" and fit it onto one small chassis for all 500 watts per channel.

http://www.parts-express.com/sure-el...campaign= pla

All that, keep in mind that owning a very large tube amplifier is much like owning a horse. Every tube is a "consumable", and around here at the typical output watts x 2.5 = input watts, you would be spending $0.35/hour to operate the beast. Keeping in mind how much of a tube amp's consumption goes up in heat vs. a solid-state device.

At this moment, I have four (4) tube amplifiers in the inventory, from the honking Scott LK150 at the one end, to the Dynaco ST35 at the other. When I need brute force (Maggies, AR3as), I have a couple of very large HK SS power amps to pull those trains.

Peter Wieck
Melrose Park, PA
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Tim Wescott Tim Wescott is offline
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 09:19:23 -0600, boomer#6877250 wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


AM Radio stations used some that would do 50,000W, I believe. Is that
sufficient?

You don't want the "most powerful" tube -- you just want one that fits
your wimpy (relative to "big radio") requirements.

If you're serious about this, get this book. It'll provide hours of
drooling entertainment if you're just a fanboy, so it'll still be worth
it:

https://www.tubesandmore.com/product...be-manual-tt-5

There are a lot of tubes that will do your job that are both in that book
and available.

The 1625 is basically an 807 with a different base and a 12V filament --
all other ratings are the same. It's much cheaper than the 807 from
tubesandmore.com. Eight of them (enough to do 500W) is cheaper than a
pair of 813's, and they'll run at a much less lethal plate voltage.

A pair of 4-1000A tubes would be dandy, but I don't know where to find
them (I'm a fanboy, not an expert).

Note that ALL of the tubes I'm mentioning here are radio tubes, not
audiophile tubes -- if you judge an amplifier by more than how hot it
gets and how much it costs, you may not be happy with the sound.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com


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Dave Platt[_2_] Dave Platt[_2_] is offline
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Default What is the most powerful audio output tube?

In article ,
Tim Wescott wrote:

If you're serious about this, get this book. It'll provide hours of
drooling entertainment if you're just a fanboy, so it'll still be worth
it:

https://www.tubesandmore.com/product...be-manual-tt-5


Scan available for free at http://w5jgv.com/downloads/RCA-TT-5.PDF
(although the price of the Tubes And More reprint is an excellent one!)

The application tables for AF power amplifier and modulator service
start on page 88. The 7650 and 833A seem to be the brutes of the lot.


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Bitrex Bitrex is offline
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Default What is the most powerful audio output tube?

On 12/08/2016 11:59 AM, John Larkin wrote:
On Thu, 8 Dec 2016 10:39:35 -0500, bitrex
wrote:

On 12/08/2016 10:19 AM, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


The output tranny required for 500 watts RMS is going to be a huge piece
of ****-off iron that will probably set you back the better part of a
grand, at least.

500 watts RMS from four tubes will require you to step up way beyond
6L6es and 807s, I think. You're probably going to want to look at
something like RF power triodes or tetrodes, 813s or the GU-13 if you're
okay with going ex-Soviet.

I am not a pro tube guy though so that's just my guess.


The transformer is the problem, especially if you go with a giant
transmitting tube that runs at high plate voltages.


Yeah, not to mention the "instant death" ~1.5kV supply and cap bank that
would be required to feed such a beast.

There have been transformerless audio power amps, using that beast
low-mu triode tube, the one Tek used in their B+ regulators.


I think that's the 6080/6AS7. I saw a 50 watt OTL amp that used
something like 8 or 12 of 'em in push pull parallel to hit that.

I can't even imagine what you'd have to throw at that topology to get 500.

Why not use mosfets? Toobs are silly.


An OTL headphone amp using say a single 6N7 power triode for each
channel and something like a 12AU7 used as a diff-pair gain stage would
be a nice weekend project for maybe half a watt per channel - way more
than required.

You can drive MOSFETs or tubes of the same polarity stacked totem-pole
from a tube diff pair, but the driver design has to be a little clever
to equalize output impedance and gain between the stages:

http://www.tubecad.com/2010/12/29/Low-Voltage%20OTL.png

I'd question my sanity if I started thinking about a 500 RMS watt
all-tube amp though. Well, this guy actually did do something rather crazy:

http://www.chambonino.com/construct/const9.html

Output transformer looks like it weighs about as much as I do.
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Tauno Voipio Tauno Voipio is offline
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Default What is the most powerful audio output tube?

On 8.12.16 19:44, Tim Wescott wrote:
On Thu, 08 Dec 2016 09:19:23 -0600, boomer#6877250 wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


AM Radio stations used some that would do 50,000W, I believe. Is that
sufficient?

You don't want the "most powerful" tube -- you just want one that fits
your wimpy (relative to "big radio") requirements.

If you're serious about this, get this book. It'll provide hours of
drooling entertainment if you're just a fanboy, so it'll still be worth
it:

https://www.tubesandmore.com/product...be-manual-tt-5


Eimac's 'The Care and Feeding of Power-grid Tubes' is also very good,
if it is somewhere to be found.

A pair of 4-1000A tubes would be dandy, but I don't know where to find
them (I'm a fanboy, not an expert).


For Class-B push-pull a pair of zero-bias triodes is much easier
to handle, e.g. 3-500Z or 3-1000Z. The kilowatt tubes are a bit
of overkill for 500 W output.

Note that ALL of the tubes I'm mentioning here are radio tubes, not
audiophile tubes -- if you judge an amplifier by more than how hot it
gets and how much it costs, you may not be happy with the sound.


Right - the big tubes are classified as transmitting tubes even when
they are used in high-level AM modulators (where IMHO the biggest
audio outputs are used).

--

-TV

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Bitrex Bitrex is offline
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Default What is the most powerful audio output tube?

On 12/08/2016 02:18 PM, bitrex wrote:

I'd question my sanity if I started thinking about a 500 RMS watt
all-tube amp though. Well, this guy actually did do something rather crazy:

http://www.chambonino.com/construct/const9.html

Output transformer looks like it weighs about as much as I do.


There's not nearly enough protection on that monster for my liking,
either. If I were crazy enough to build something like that I'd probably
have a dedicated uP on every output tube monitoring all the
voltages/currents of interest and shutting everything down quickly if
something looked amiss.

Those transformers don't look cheap.
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Cursitor Doom Cursitor Doom is offline
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 15:51:54 +0000, Ralph Barone wrote:

Go big or go home. http://www.g8wrb.org/tetrodes/


The last toob in that list (1MW) has the comment "the ultimate tube for
QRP" so I'm guessing this person doesn't know his Ps for his Os. Unless
he's aiming for ultimate sarcasm.



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boB boB is offline
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).



How about a high AVERAGE output wattage ?



boB
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Bitrex Bitrex is offline
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Default What is the most powerful audio output tube?

On 12/08/2016 11:55 AM, John Larkin wrote:
On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


https://dl.dropboxusercontent.com/u/.../Tubes/833.jpg



The ex-Soviet version GU-48 are pretty cheap on eBay...
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Tim Wescott Tim Wescott is offline
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 21:19:52 +0200, Tauno Voipio wrote:

On 8.12.16 19:44, Tim Wescott wrote:
On Thu, 08 Dec 2016 09:19:23 -0600, boomer#6877250 wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6
tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6,
but after careful research, it's almost identical, but with a
different envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel),
from all tubes, .... With four 6L6 tubes in PPP, I can only get around
120W RMS (per channel).


AM Radio stations used some that would do 50,000W, I believe. Is that
sufficient?

You don't want the "most powerful" tube -- you just want one that fits
your wimpy (relative to "big radio") requirements.

If you're serious about this, get this book. It'll provide hours of
drooling entertainment if you're just a fanboy, so it'll still be worth
it:

https://www.tubesandmore.com/product...be-manual-tt-5


Eimac's 'The Care and Feeding of Power-grid Tubes' is also very good,
if it is somewhere to be found.

A pair of 4-1000A tubes would be dandy, but I don't know where to find
them (I'm a fanboy, not an expert).


For Class-B push-pull a pair of zero-bias triodes is much easier to
handle, e.g. 3-500Z or 3-1000Z. The kilowatt tubes are a bit of overkill
for 500 W output.


May not be the best sounding result if you're going for audiophoolery.
Low-mu triodes with the grid voltages negative would be best then, or AB1
beam tubes, maybe.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com
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John L Stewart John L Stewart is offline
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Location: Toronto
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Smile

Here Ya Are! Add a couple more KT88s & you are there.

John L Stewart
Attached Images
 
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piglet piglet is offline
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Default What is the most powerful audio output tube?

On 08/12/2016 15:19, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


I had one of these in my collection:

http://r-type.org/exhib/aaa1098.htm

sold it on ebay to some audio guy for lot of money

The heater alone consumes 90 watts.

piglet



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Roger Hayter Roger Hayter is offline
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Default What is the most powerful audio output tube?

boB wrote:

On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).



How about a high AVERAGE output wattage ?



boB


I think you are fighting a losing battle here. About 10 or 20 years ago
I wrote to the editors of the RSGB magazine complaining about "RMS
power" being used in an article they published and they refused to
publish my letter, apparently on the grounds that I was a boring pedant.
Admittedly AM does get a bit complicated when the peak RF power of an AM
transmitter is a real power (not an instaneous peak of a sinewave)
whereas it represents the peak of an audio waveform of which the power
is not determined by the level of this peak. But there is still no
such thing as RMS power.

--

Roger Hayter
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Default What is the most powerful audio output tube?

wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).



http://www.g8wrb.org/data/Eimac/8973.pdf A pair will give you over two
megawatts.

--
Never **** off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)
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John L Stewart John L Stewart is offline
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Smile

Quote:
Originally Posted by View Post
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).
--------------------------------------------

Early in my career as I interned for my P.Eng I built a regulated DC power supply. 4.5 KV at One amp ain't easy. And one needs lots of safety systems, otherwise death is a sure thing.

The passers were 3X 304TH, all grids driven +ve. It ran a Philips cooking magnetron continuously, driving an experiment involving active Nitrogen in an evacuated glass vessel, my supervisors Prof JSM (Andy) Anderson's experiment at the time. Was about 1960.

The safety system did operate on one occasion as it discharged the storage caps after a fault. Lots of noise from that explosion. But it saved my ass!
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Default What is the most powerful audio output tube?

wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

4CX25000A would be good! Hmmm, I think the filament runa about 10 V at 170
A, you can run at least 10 KV on the anode at several amps. The output
transformer would be about the size of a small car.

I was at a Greatful Dead concert in 1969 at the Fox Theater in St. Louis,
and they used the modulator out of an AM broadcast transmitter as an audio
amp. The tubes were about a foot in diameter.

Jon
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Big Bad Bob Big Bad Bob is offline
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Default What is the most powerful audio output tube?

On 12/08/16 08:55, John Larkin so wittily quipped:
On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?


[snip]

https://dl.dropboxusercontent.com/u/.../Tubes/833.jpg


big sucker. 4 terminals, so I'm guessing it's a power triode for RF
output, directly heated cathode. Lots of 'issues' powering it up for an
audio amplifier. You'll need a center-tapped cathode supply, for
starters, and a fixed bias supply for the control grid. Since the
control grid [appears to be] on one of the 'cap' electrodes, it's
probably designed to operate at a positive voltage for class C
operation. So a Class 'A' or push-pull 'AB' might not give you the
results you want. I could see AB2 maybe working, but lots of
experimenting involved in making something like *THAT* "fit".

better to use KT88 or similar [like a Marshall amplifier]

http://www.drtube.com/library/schema...-schemas#Major

http://www.drtube.com/schematics/marshall/200w.gif
(a generic schematic)

4 of them gets you 200W. I guess 8-10 would get you 500W with the right
transformer.




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Peter Wieck Peter Wieck is offline
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Default What is the most powerful audio output tube?

I dunno - the OP asked about *AUDIO* output tubes. Kinda-sorta puts transmitter tubes out of the realm of discussion. I still think the KT family is the best avenue to explore - starting with the KT88.

Peter Wieck
Melrose Park, PA
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Default What is the most powerful audio output tube?

On 12/08/16 11:18, bitrex so wittily quipped:
I'd question my sanity if I started thinking about a 500 RMS watt
all-tube amp though. Well, this guy actually did do something rather crazy:

http://www.chambonino.com/construct/const9.html

Output transformer looks like it weighs about as much as I do.


I like it already.

You win!


--
your story is so touching, but it sounds just like a lie
"Straighten up and fly right"
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Default What is the most powerful audio output tube?

On Thursday, December 8, 2016 at 3:20:48 PM UTC, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?


There is a self-contradiction in this question. There are lots of really powerful tubes but they aren't audio tubes; many sound like ****. There is, even today, plenty of choice in quality audio tubes that sound great, but they aren't necessarily all that powerful. In hi-fi, furthermore, it is accepted that you sacrifice some of the available power to operate the tube on the flattest part of its transfer curve, so that mitigates against hogging out all the available power. Also, the most refined audio sound comes from triode tubes, which are pretty inefficient, meaning you need lots or very big, not ones to make any appreciable power.

However, unlike some of the advice that you're getting here from people who've never built or heard a big tube amp, there are ways to get around it. First of all, you can parallel standard tubes like KT88 to your heart's content (well, actually the depth of your pocket, because the custom iron will cost plenty); I had a big OTL KT88 amp built as a modular rack mount system that by rewiring would give any output you wanted; it took up two bays; but it sounded like what it was, a PA system. Even the humble EL34 can build into a very potent amp: I got 96W of high quality audio sound out of parallel push-pull tubes running in class A/B with toroidal trannies in a stereo amp that two people could handle with ease, one with some difficulty; for home use it had 18W in Class A, so the massive oomph was rarely needed.

Next, some of the broadcast tubes sound fabulous, for instance the 845 broadcast triode, and you can parallel triodes in single-ended output for the finest sound of all, zero negative feedback SE, same as you can pentodes in push-pull. For instance, my 80W SE amps were deliberately operated at only a fraction of theoretical output to linearize the sound. I could as easily have chosen your 500W output if I were willing to sacrifice some sound quality; instead I put the time and the money into high-sensitivity speakers.

None of this throws up insuperable technical problems. The biggest problem of big amps is in fact the availability and cost of very high voltage connectors for the separate components, or the monstrous weight if you build the thing in one unit. For my 80W SE amp, Menno van der Veen designed the transformers for me, and Plitron wound them, and listed them for the intrepid. But it is long since broken up as too heavy, too hot, too large, too dangerous, just too unnecessary. The booster amp, 3.8W of SE 300B, with a bicor horn turned out to produce all the sound pressure I actually need. (A booster amp is a complete small power amp you use to drive a much larger power amp.) Don't laugh. When a sports field across the street from my house annoyed me with their unshielded PA, I coupled my 3.8W 300B SE amp and bicor horns to the stairwell in my four-storey town house, opened the front doors, and blasted their premier event of the year into incoherence. They scrapped the offending PA the next day.

***
If you're just building a humongous amp to prove you're a swinging dick, great, I admire initiative and balls and magnificent obsessions. But if you have a real problem to solve, like x sound pressure in y spatial volume, I suggest you redefine your need working backwards from the speakers: if your speakers are sensitive, a Bessel Array or bicor horns, the amp soon gets down to a practical size and electrical requirement and the costs start approximating reality as she is lived.

For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm
And the smallest of my bicor horns looks like this inside:
http://www.audio-talk.co.uk/fiultra/...20T91HWAF3.jpg

Andre Jute
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Default What is the most powerful audio output tube?

On 12/14/16 08:25, Andre Jute so wittily quipped:
For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm


too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...

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Peter Wieck Peter Wieck is offline
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Default What is the most powerful audio output tube?

On Wednesday, December 14, 2016 at 12:15:06 PM UTC-5, Big Bad Bob wrote:
On 12/14/16 08:25, Andre Jute so wittily quipped:
For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm


too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...


If you want an excellent example of a really *bad* array, look at the Bose 901 in any of its iterations. Bleeding ears are very nearly a certainty with such a device. Further, as this case illustrates all to well, William of Occam had it right: Eschew needless complexity. There is no valid reason other than as a tour-de-force to create such an array in a non-specialized application when many and far better alternatives are available, including any of several well-established planar options.

As to very large tube power-amps, given the inherent physical and safety issues involved mixed with the very real costs mixed with the time involved - this is almost why PERT would be a better project management tool than CPA.. CPA is designed to reach a specific goal by a specific time. PERT is designed to reach a specific goal by the most effective process - time not being at issue. Getting a man on the moon was done via PERT, developed by the US Navy for their ballistic missile (Polaris) program. Coupled with CPA/M it became the tool-of-choice for complex projects delving into uncharted processes.

Speakers are an exercise in moving air. Not in large distances, but in many, very small movements so as to attempt to duplicate sounds recorded somewhere else. Complex sounds in considerable volume require complex means to reproduce - also in considerable volume *relative* to the listening area. If we exclude headphones (no one needs 500W for headphones), the amount of energy required to move sufficient air will be proportionate to the volume to be filled, but that proportion will not be linear.

My personal gold standard for testing a system is this:

https://www.discogs.com/Saint-Sa%C3%...elease/7664706

Recorded right down the street from where I was living at the time. My listening room was then 16 x 27 x 9.5 feet (~4,100 c.f./410 c.m.), so not a small venue. Today it is 17 x 28 x 10 - a touch more difficult. I could do a credible reproduction in the former location with a 425 watt/4/rms amp into AR 9 speakers. Today, it is a 225 watt/6/rms amp into big maggies (MGIIIa).

Between the two ARs, I had 570 square inches of active radiating surface. Between the two Maggies, I have 2,550. Maggies, albeit power-pigs, are spoilers and will ruin a listener forever. But, the point is that single-source/single-driver speakers simply cannot move enough air to make a dent in complex sources at complex volumes in challenging settings - may as well not even waste one's time. Bessel Arrays are possible options - but pretty much doomed to failure unless taken as an exercise in their own right. And, as it happens, when proposed 'back in the day' they were listed as a "high-powered option".

(My, but this is turning into a bit of a rant)

As it happens, the differences between tubes and SS are being discussed in another forum, and citing all kinds of sources, one of which is: http://www..dwfearn.com/tubes_vs_transistors.html Note the date.

Solid-state has evolved considerably in the last 44 years. To the point where the actual differences between the two, while real, are to where one will be challenged to say which is a superior option for the reproduction of music. Tube technology and/or topology has not evolved in any meaningful way over that same time. I would suggest that the OP go ahead and purchase a couple of 500 watt Class D modules (https://www.amazon.com/1000W-Stereo-...X6CTSDKFRGB39M as a full kit) and see what 500 watts sounds like before spending perhaps 20 x that cost for a similarly powerful tube device.

I am emphatically *not* attempting to discourage the OP from pursuing a dream. What I am suggesting is that the OP do the research (other than here), perhaps check in a few of the DIY venues for similar projects, get some advice from those that have done it. I would also strongly suggest getting in touch with Patrick Turner ( http://www.turneraudio.com.au/ ) who is a past-master at specialty and exotic tube amps, winds his own transformers and might be convinced to wind again for others (at a cost, but well worth it). In other words, set a goal and make a plan to reach it.

Many of us here have the solder scars and history to show for some passing acquaintance with the means, methods and related skills and processes associated with the tube hobby. Several glaring examples do not, having a more developed Munchhausen complex to make up for that lack. Writing for myself, my preference is towards the restoration, care and feeding of vintage equipment designed by others but open to improvement. I have designed and built one (1) amp 'from parts' for myself, and have the makings (Iron) for one other. The former is based on the venerable 6BQ5 in PP. For the other, I am torn between several from the 6V6 at one end and the 5881 at the other. It will be some years. But, the point, again, is that there is very little new under the sun in tubes. No need to invent the wheel from scratch when there is so much knowledge and material available that needs only to be refined and executed.

Rambling back to speakers: one wants speakers to be able to handle the most quiet passages with grace and clarity, yet bring that same grace and clarity to those that are 30dB louder. And electronics that are capable of the same. Many speakers 'break up' if required to produce across that range cleanly.

Gets down to Horses for Courses. If one lets the amount of power available drive the choice of speakers, one severely limits one's choices and options, as well as severely limits the types of signal as may be processed cleanly. If, on the other hand, one lets the speakers drive the power requirements, then the choices are near-infinite. And why I fully support the concept of a 500 watt tube amp - overcoming the primary fault of tube amplifiers everywhere *NOT* enough power. I am _always_ curious of what can be done with various parts-and-pieces. Over the next several months, I will be culling the herd developed by this curiosity and parting with five power amplifiers, two pre-amps, two tuners and various other bits and pieces. All fun. None very costly, none very significant. But, to repeat, all fun. And I have to make room for the next lot!

End ramble/rant.

Peter Wieck
Melrose Park, PA


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Default What is the most powerful audio output tube?

On Wednesday, December 14, 2016 at 5:15:06 PM UTC, Big Bad Bob wrote:
On 12/14/16 08:25, Andre Jute so wittily quipped:
For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm


too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...


Well, I had to make a guess at what the OP wants to do with all of 500W, and the obvious answer is a very big wall of sound in a very big space, which is why I brought up the Bessel Array. The horn I also mentioned is better scaled to domestic situations though, as I also demonstrated, with minimal effort it can be made to go BIG.

However, I must tell you, in an open-plan house I divided a floor between my study and my studio with a Bessel wall of ESL-63, driven in stereo by QUAD II (all the gimmicking was done in a custom preamp) and later by ex-BBC silicon QUAD amps rebuilt at the factory, and that was a superb domestic implementation, albeit one where you had to be careful with the volume knob if you didn't want to land in the divorce courts. I could walk around in the orchestra that setup made. So, if you have your mind in gear, and maybe have the components already, Bessel does scale, but in general you're right, Bessel just isn't economical or practical to build from scratch unless you want to reach thousands of people.

Andre Jute
The best sound is mainly a matter of what you're used to hearing
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Default What is the most powerful audio output tube?

On Wednesday, December 14, 2016 at 1:23:51 PM UTC-6, Andre Jute wrote:
On Wednesday, December 14, 2016 at 5:15:06 PM UTC, Big Bad Bob wrote:
On 12/14/16 08:25, Andre Jute so wittily quipped:
For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm


too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...


Well, I had to make a guess at what the OP wants to do with all of 500W, and the obvious answer is a very big wall of sound in a very big space, which is why I brought up the Bessel Array. The horn I also mentioned is better scaled to domestic situations though, as I also demonstrated, with minimal effort it can be made to go BIG.

However, I must tell you, in an open-plan house I divided a floor between my study and my studio with a Bessel wall of ESL-63, driven in stereo by QUAD II (all the gimmicking was done in a custom preamp) and later by ex-BBC silicon QUAD amps rebuilt at the factory, and that was a superb domestic implementation, albeit one where you had to be careful with the volume knob if you didn't want to land in the divorce courts. I could walk around in the orchestra that setup made. So, if you have your mind in gear, and maybe have the components already, Bessel does scale, but in general you're right, Bessel just isn't economical or practical to build from scratch unless you want to reach thousands of people.

Andre Jute
The best sound is mainly a matter of what you're used to hearing


Hey Andre!

Merry, Merry!

Happy, Happy!

Ears to you 8*D

Al Marcy
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Default What is the most powerful audio output tube?

On Thursday, December 15, 2016 at 2:00:51 AM UTC, Alan Marcy wrote:
On Wednesday, December 14, 2016 at 1:23:51 PM UTC-6, Andre Jute wrote:
On Wednesday, December 14, 2016 at 5:15:06 PM UTC, Big Bad Bob wrote:
On 12/14/16 08:25, Andre Jute so wittily quipped:
For a Bessel Array, try the brief introduction he
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm

too brief, though you piqued my curiosity.

Then I went he
http://www.angelfire.com/sd/paulkemble/soundf.html

and my curiosity 'peaked'. Interesting, but why do you WANT "that much"
sound pressure now?

my ears bleed just thinking about it...


Well, I had to make a guess at what the OP wants to do with all of 500W, and the obvious answer is a very big wall of sound in a very big space, which is why I brought up the Bessel Array. The horn I also mentioned is better scaled to domestic situations though, as I also demonstrated, with minimal effort it can be made to go BIG.

However, I must tell you, in an open-plan house I divided a floor between my study and my studio with a Bessel wall of ESL-63, driven in stereo by QUAD II (all the gimmicking was done in a custom preamp) and later by ex-BBC silicon QUAD amps rebuilt at the factory, and that was a superb domestic implementation, albeit one where you had to be careful with the volume knob if you didn't want to land in the divorce courts. I could walk around in the orchestra that setup made. So, if you have your mind in gear, and maybe have the components already, Bessel does scale, but in general you're right, Bessel just isn't economical or practical to build from scratch unless you want to reach thousands of people.

Andre Jute
The best sound is mainly a matter of what you're used to hearing


Hey Andre!

Merry, Merry!

Happy, Happy!

Ears to you 8*D

Al Marcy


Hey, Al! Longevity rules!

Andre Jute
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Default What is the most powerful audio output tube?

On 12/14/16 11:23, Andre Jute so wittily quipped:
The best sound is mainly a matter of what you're used to hearing


With all of the speaker systems I've built over the years [or installed
in cars], the BEST overall seems to be like this:

a) decent quality car stereo 'coaxial' speakers with built-in
crossovers, etc. [currently using tri-axials]

b) infinite baffle enclosure (3 cubic feet for 6x9) with 3x4x5 ratio,
lined with acoustic absorbing material and built of something that
generally doesn't have resonance [presswood sides, plywood front for
example].

c) a decent quality tube or solid state amplifier with good headroom and
low distortion driving it.


the speaker system I have right now is just like that. It has good low
end, good high end, and collectively sounds like the Sennheiser
headphones I use for recording [though the headphones do have slightly
better bass response, it's not that different].

It's easy to find CRAP speakers that pretend to have a reasonably flat
response. So you have to listen to every one of them in a 'demo wall'
someplace to make sure it has a flat response. It also means you need
to know what a flat response SOUNDS like.

Fortunately, THAT is what I'm "used to hearing".

The 'coaxial' speakers aren't the most efficient, but they're already
balanced and you will have only limited phasing problems throughout the
entire listening range. Usually they have heavy cone woofers with large
magnets, so their resonance is reasonably low in frequency. So you
don't need bass reflex, which has other problems. Just put it into
'infinite baffle' and it should work well. Also whateve grill cloth you
use should not affect the sound. I use 'Peavey' (aftermarket) grill
cloth, available from most musician supply places online.


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Default What is the most powerful audio output tube?

On Thursday, December 15, 2016 at 2:07:33 PM UTC-5, Big Bad Bob wrote:
On 12/14/16 11:23, Andre Jute so wittily quipped:
The best sound is mainly a matter of what you're used to hearing


Audition a pair of Maggies - even in a difficult setting. Just for giggles.

Peter Wieck
Melrose Park, PA


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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).\


I have a couple of used - but gently treated - EIMAC 4CX3000A tetrodes
that I'd be willing to part with. If you're interested, email me with
a bid.
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Default What is the most powerful audio output tube?

On Thu, 08 Dec 2016 08:59:20 -0800, John Larkin
wrote:

On Thu, 8 Dec 2016 10:39:35 -0500, bitrex
wrote:

On 12/08/2016 10:19 AM, wrote:
What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).


The output tranny required for 500 watts RMS is going to be a huge piece
of ****-off iron that will probably set you back the better part of a
grand, at least.

500 watts RMS from four tubes will require you to step up way beyond
6L6es and 807s, I think. You're probably going to want to look at
something like RF power triodes or tetrodes, 813s or the GU-13 if you're
okay with going ex-Soviet.

I am not a pro tube guy though so that's just my guess.


The transformer is the problem, especially if you go with a giant
transmitting tube that runs at high plate voltages.


---
Which transformer?
---

There have been transformerless audio power amps, using that beast
low-mu triode tube, the one Tek used in their B+ regulators.


---
Which low-mu triode is that?
---

Why not use mosfets? Toobs are silly.


---
But forgiving, and they generally won't give up the ghost until the
cathode's coating is depleted or the envelope melts and the vacuum
sucks it in

JF
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Default What is the most powerful audio output tube?

You might consider the 5831:
https://frank.pocnet.net/sheets/201/5/5831.pdf

No, I haven't used them, but the data sheet rates them for Class-B audio
use at 370kW per pair!!
You'll need a heater supply of 2100A per tube, & the rest in proportion.
I don't want to hear about your power bills, either :-)

On 13/12/2016 2:40 AM, Big Bad Bob wrote:
On 12/08/16 08:55, John Larkin so wittily quipped:
On Thu, 08 Dec 2016 09:19:23 -0600, wrote:

What is the most powerful audio output tube, as far as RMS wattage
output?


[snip]

https://dl.dropboxusercontent.com/u/.../Tubes/833.jpg


big sucker. 4 terminals, so I'm guessing it's a power triode for RF
output, directly heated cathode. Lots of 'issues' powering it up for an
audio amplifier. You'll need a center-tapped cathode supply, for
starters, and a fixed bias supply for the control grid. Since the
control grid [appears to be] on one of the 'cap' electrodes, it's
probably designed to operate at a positive voltage for class C
operation. So a Class 'A' or push-pull 'AB' might not give you the
results you want. I could see AB2 maybe working, but lots of
experimenting involved in making something like *THAT* "fit".

better to use KT88 or similar [like a Marshall amplifier]

http://www.drtube.com/library/schema...-schemas#Major

http://www.drtube.com/schematics/marshall/200w.gif
(a generic schematic)

4 of them gets you 200W. I guess 8-10 would get you 500W with the right
transformer.



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Big Bad Bob Big Bad Bob is offline
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Default What is the most powerful audio output tube?

On 01/10/17 23:09, David R Brooks so wittily quipped:
You might consider the 5831:
https://frank.pocnet.net/sheets/201/5/5831.pdf

No, I haven't used them, but the data sheet rates them for Class-B audio
use at 370kW per pair!!
You'll need a heater supply of 2100A per tube, & the rest in proportion.
I don't want to hear about your power bills, either :-)


let alone, the size of the output transformer


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Patrick Turner Patrick Turner is offline
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Default What is the most powerful audio output tube?

What is the most powerful audio output tube, as far as RMS wattage
output?

I have gotten some powerful sound from four 6L6 tubes in push-pull
parallel. but I want more. I know it's possible to use eight 6L6 tubes,
which I believe is called " push-pull parallel - parallel", but I'm
looking into other possible tubes.

At one time, I thought the 807 tube was more powerful than the 6L6, but
after careful research, it's almost identical, but with a different
envelope (plate on the top cap).

I'm looking to get a full 500W RMS (or more) output (per channel), from
all tubes, .... With four 6L6 tubes in PPP, I can only get around 120W
RMS (per channel).

Your initial question asks what is the most powerful vacuum tube, and if you were to consider those used for Russian AM radio stations transmitting say 500kW to jam Radio America then you'd need huge power supply, and tubes are as big as one of the rooms at the Kremlin.

But seriously, a pair of 6L6GC can put out a safe reliable 40W class AB1 with Ea = 450Vdc, Ia of each 6L6 at idle = 30mAdc, and PP OPT anode primary load of about 4k0.
For 500W, you just need 13 pairs of 6L6, Ea = 450Vdc, Iadc for 26 6L6 = 0.78Amps dc, and OPT anode primary load = 308r, but with core and wire all rated for 500W, not 40W.

You will find that you could use 8 pairs of 6550, or 6 pairs of KT120 for similar high power.

In 2001 I made two "300W" amps which could actually produce 400W each with 6 pairs of 6550. Each amp had a PS weighing 25Kg, and with audio chassis weighing 25Kg, including a an E&I OPT with 50mm tongue x 110mm stack height.
See my website at www.turneraudio.com.au

What you will find is that as the power goes higher, the cost per Watt of power goes lower, and that if the PSU and audio chassis is doubled in weight, you can get 2,000W.

Patrick Turner.
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