I have acquired an old Magnavox console stereo. The turntable works but it's
motor-to-table mechanics are jerky and does not play records properly. No
biggie to me. I'm interested in the amp!

To get this started, I have posted some pictures of the stereo and amp on my
server. Try: http://2xl.homelinux.com/Audio/Magnavox_Amp/index.html.

The amp seems to be a 2-channel stereo amplifier. It uses 2 12AX7's for
drivers into 4 6V6GT output tubes with a 5U4GB rectifier. It has a 7025
tube on the input. I'm assuming it is a pre-amp to make up for the low
input signal coming from the turntable. This leads into my first question.
A 7025 is also a 12AX7. Why did they print 7025 on the chassis when clearly
they could have put another 12AX7 stamp on it? Is there something about a
7025 this amp needs? Seems to work fine with a 12AX7.

On the chassis underside, there is a capacitor that looks to have been cut
from the circuit. I know that this unit has been serviced before and I'm
wondering what (if any) significance this has on the amp. A picture of this
is he http://2xl.homelinux.com/Audio/Magnavox_Amp/badcap.jpg.

A few other questions I have someone may know.

What would be the output power range (for speaker matching) for this amp?
Any suggestions on upgrades for this amp? Is there a way to bypass the
extra input amplification stage to handle "line-level" inputs like from a
CD player or tuner?

I thank everyone for taking their time in reading my post.

Ty Unes -

Ty Unes wrote:

I have acquired an old Magnavox console stereo. The turntable works but
it's motor-to-table mechanics are jerky and does not play records
properly. No biggie to me. I'm interested in the amp!

To get this started, I have posted some pictures of the stereo and amp on
my server. Try: http://2xl.homelinux.com/Audio/Magnavox_Amp/index.html.

The amp seems to be a 2-channel stereo amplifier. It uses 2 12AX7's for
drivers into 4 6V6GT output tubes with a 5U4GB rectifier. It has a 7025
tube on the input. I'm assuming it is a pre-amp to make up for the low
input signal coming from the turntable. This leads into my first question.
A 7025 is also a 12AX7. Why did they print 7025 on the chassis when
clearly they could have put another 12AX7 stamp on it? Is there something
about a 7025 this amp needs? Seems to work fine with a 12AX7.

A few other questions I have someone may know.

What would be the output power range (for speaker matching) for this amp?
Any suggestions on upgrades for this amp? Is there a way to bypass the
extra input amplification stage to handle "line-level" inputs like from a
CD player or tuner?


i have this same amp & i have been using it for over 10 years. this is a
fine low power amp that delivers a average of 10 watts per channel. i am
driving a pair of low power curtis-mathes speakers that are rated at 20
watts per pair & are comparable to the OEM magnavox speaker system. the CM
speakers use a 12" woofer, a horn midrange & a 2" tweeter.
i am using a ESS solid state preamp connected directly to the phono inputs
on the magnavox amp. i did not eliminate the 7025. this amp sounds sweet.
regarding the difference between the 7025 & the 12AX7, the amp has a cleaner
sound with a good high frequency response using the 7025, however, when i
tried using a 12AX7, it drastically changed the high end response & the
overall sound was much "warmer"


On the chassis underside, there is a capacitor that looks to have been cut
from the circuit. I know that this unit has been serviced before and I'm
wondering what (if any) significance this has on the amp.

yes, it does. it is part of the driver circuit for that channel.
you may need to check it & solder it back in place.
also, i would recommend that you replace them ceramic tube capacitors with
good polypropolene or mylar capacitors.
--
It's a shame Linux has such difficulty running some of the more popular
Windows applications: Nimda, CodeRed, Klez, WPA, Swen, SoBig, ILOVEYOU,
MyDoom, Witty, Netsky, sober, Mimail, Dumaru......

Windows was created to keep idiots away from Unix.

On Thu, 30 Jun 2005 19:20:27 GMT, Ty Unes wrote:

I have acquired an old Magnavox console stereo. The turntable works but it's
motor-to-table mechanics are jerky and does not play records properly. No
biggie to me. I'm interested in the amp!

To get this started, I have posted some pictures of the stereo and amp on my
server. Try: http://2xl.homelinux.com/Audio/Magnavox_Amp/index.html.

The amp seems to be a 2-channel stereo amplifier. It uses 2 12AX7's for
drivers into 4 6V6GT output tubes with a 5U4GB rectifier. It has a 7025
tube on the input. I'm assuming it is a pre-amp to make up for the low
input signal coming from the turntable. This leads into my first question.
A 7025 is also a 12AX7. Why did they print 7025 on the chassis when clearly
they could have put another 12AX7 stamp on it? Is there something about a
7025 this amp needs? Seems to work fine with a 12AX7.

On the chassis underside, there is a capacitor that looks to have been cut
from the circuit. I know that this unit has been serviced before and I'm
wondering what (if any) significance this has on the amp. A picture of this
is he http://2xl.homelinux.com/Audio/Magnavox_Amp/badcap.jpg.

A few other questions I have someone may know.

What would be the output power range (for speaker matching) for this amp?
Any suggestions on upgrades for this amp? Is there a way to bypass the
extra input amplification stage to handle "line-level" inputs like from a
CD player or tuner?

I thank everyone for taking their time in reading my post.

Ty Unes -


I can't believe my eyes. I designed those transformers in
the early 1960's. The power transformer has a 300-xxx-x
part number and the output transformers have a 320-xxx-x number
and the filter choke is also a 320 series number. The output
transformers will handle 8 watts. I think that they have an 8 ohm
output impedance and that Magnavox originally used Jensen speakers
that were adequate.

Thanks for the memories.

Jerry

Jerry wrote:

I can't believe my eyes. I designed those transformers in
the early 1960's. The power transformer has a 300-xxx-x
part number and the output transformers have a 320-xxx-x number
and the filter choke is also a 320 series number. The output
transformers will handle 8 watts. I think that they have an 8 ohm
output impedance and that Magnavox originally used Jensen speakers
that were adequate.

Thanks for the memories.

Jerry

Jerry,

Amazing! I can't believe you designed these transformers!- LOL I went back
to my pics and tried to figure out how you saw the numbers on the
x-formers. Good eyes!

OK, info so far is 8 watts into 8 ohms. The 7025 tube sounds crisper in the
high-end than the 12AX7.

I still don't know what the best way is to run "line-level" into this amp.
One person suggested wiring the inputs directly to the grids of the 12AX7
preamps, another uses an external preamp right into the existing inputs.
Not a big deal though, I can do either.