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Magnavox 6V6 circuit and output transformers.

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M Gregg

M Gregg

Disabled Account
Joined 2010
Just asking,

Does anyone know what type of Output transformers were used on the Magnavox 6V6 PP stereo and something of equal quality available now?
(Yes I know its a Cliché "Quality" I'm thinking about the feel/sound if you know what I mean)
I'm assuming they were something like Stancore but its just a guess and what actual primary impedance that was used on the amps.

And can anyone post the original schematic if they have a copy..thank's. :D
I have had a look on the net but its a bit variable..
This is the best I have managed to find, however I'm wondering how many versions were made and which was the best version.
The reason is I have found four black glass 6V6 in a box in the shed.:D (New unused)

Then I saw this on youtube and the dewey eyes started..LMAO I even have a copper plate..:D

https://www.google.co.uk/search?q=magnavox+copper+utube&biw=1280&bih=585&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoA2oVChMI4-zv_KXkxgIVQa8UCh3JsQ0X#imgrc=7fldHH6B1gYZYM%3A

Just thinking about AB resistors with some kind of treatment or encapsulation and Jupiter reds or copper/wax caps.

Regards
M. Gregg
 

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M Gregg

M Gregg

Disabled Account
Joined 2010
That's interesting and a bit strange,

The output Tx windings are not balanced and C5 and C6 are different.:confused:
Your first post of between 130-150 ohms looks about right..
Time to have a think..:)
Perhaps with AB resistors a slow bake then seal the ends with slow drying epoxy then paint the whole thing with a sealant.

Regards
M. Gregg
 
Last edited:
M Gregg

M Gregg

Disabled Account
Joined 2010
lexx21 said:
The 150 ohms is most likely the DCR of the primary. The primary Z is more in the neighborhood of about 7-8k. The lower the impedance the more power but also more distortion.
Click to expand...

This is why I was wondering about the actual value used because most of the drawings seem to give this value which doesn't make much sense..
2nd table down..

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

Regards
M. Gregg
 
Last edited:
K

Koonw

Disabled Account
Joined 2013
M Gregg said:
That's interesting and a bit strange,

The output Tx windings are not balanced and C5 and C6 are different.:confused:
Your first post of between 130-150 ohms looks about right..
Time to have a think..:)
Perhaps with AB resistors a slow bake then seal the ends with slow drying epoxy then paint the whole thing with a sealant.

Regards
M. Gregg
Click to expand...

"The two different coupling caps values relate partly to the paraphase splitter..."

Yes like other already pointed out it is DCR PRI/SEC = 150/0.3, so low they can not be actual Z, which is 7-10K for Pentode mode. The DCR for pri is likely not bifilar so are copper resistance difference between the 2 windings.
 
M Gregg

M Gregg

Disabled Account
Joined 2010
jazbo8 said:
Why are you using DCR to calculate the turns or impedance ratio? The 175's OPT is rated for 6k:4~6. The coupling capacitor have different values because the NFB is applied to only one half of the input/PI pair.
Click to expand...


The question is what is the actual value of the Magnavox O/P Tx primary some people seem to have used 8K..with 6V6.

The Circuit diagrams all have F/B however the Caps are the same value on one diagram and different values C5/C6 on the other.

Regards
M. Gregg
 
M Gregg

M Gregg

Disabled Account
Joined 2010
smoking-amp said:
The two different coupling cap sizes may have been to introduce some 2nd harmonic distortion at the bass end, to cover up the poor LF response of the tiny OTs. Fake bass.

If you are building from scratch, get some real OTs.
Click to expand...

That's probably what will happen..:D

It starts as a look see then gets modified..
Perhaps something like 15 watt 8K 8ohm Edcor's

However what is the ideal Magnavox circuit?

Something like 6sl7's driving 6L6's..some think the 6V6 is better..
I don't want to go the EL route..

Regards
M. Gregg
 
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