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Old 20th December 2008, 05:51 PM   #11
packman is offline packman  Italy
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you guys give me a lot of great suggestions, great.

for guitar88: 12AY7? ECC82 are not the equivalent of the 12AU7 (have read searching in ebay)?

for Geek: because here (in my city) is not simple fo find the right material (film resistence, good caps for audio and the JJ valve etc) have you that components in stock?
thanks
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Old 20th December 2008, 08:46 PM   #12
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Of the 12AX7, 12AT7, 12AY7 and 12AU7 the 12AU7 is the lowest gain. The 12AY7 I like better for its sonic quality in guitar amplifiers. It is still a lot lower gain than the 12AX7.
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Old 20th December 2008, 09:32 PM   #13
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Default Re: nice

Hi,

Quote:
Originally posted by packman
Sure i will try your mods litterally, have to change R15 AND R16 accordingly?
Nope, just R15. The reason for that is in a long-tailed phase splitter, one side inherently has lower gain than the other. The different resistors is standard practise by manu companies to equalize the gain.

But I see someone already mentioned trying a different tube first. Try an ECC81.


Quote:
Do you think the mod reduce the brittle of the reverb a bit ?
thanks
Hard to say... I don't like "sand-state" reverb sections, so tended to avoid them.


Quote:
Originally posted by packman

for Geek: because here (in my city) is not simple fo find the right material (film resistence, good caps for audio and the JJ valve etc) have you that components in stock?
thanks
I have some stuff in stock, but don't ship to Italy as the postal loss is too high. Even registered mail goes missing

Cheers!
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Old 21st December 2008, 06:34 AM   #14
packman is offline packman  Italy
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for guitar88: "The 12AY7 I like better for its sonic quality"
ok!

for Geek: "I have some stuff in stock, but don't ship to Italy as the postal loss is too high. Even registered mail goes missing "

Really? Can be canadian-to-italy posts because i have bought a lot of items in US and never had problems (mainly with USPS).

Thanks anyway and you guys have a Great Christmas!
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Old 22nd December 2008, 12:59 AM   #15
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I'm brazilian and I make some modifications on Guitar Amplifiers like Marshall and Fender.

I think you MAY test 12at7 and 12au7 in this amplifier before starting the mods.

I use here when I don't need much distortion 12au7. But some friends use 12ay7 too and them liked these two tubes.

Best regards.
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Old 22nd December 2008, 05:15 AM   #16
45 is offline 45  Italy
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Quote:
Originally posted by packman
you guys give me a lot of great suggestions, great.

for guitar88: 12AY7? ECC82 are not the equivalent of the 12AU7 (have read searching in ebay)?

thanks
12AY7 has no european equivalent in my knowledge.
Other american equivalts of 12AY7 are 6072, 6072A.

12AU7 is the american equivalent of ECC82.

ECC82-12AU7 exist in several versions: E82CC, ECC802S, 12AU7A, 5814 and some other less common.

However 12AY7, 12AU7 and 12AX7 all have the same pin-out and filament supply requirements.

Cheers!
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Old 22nd December 2008, 05:58 AM   #17
packman is offline packman  Italy
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Quote:
Originally posted by mod_evil
[I think you MAY test 12at7 and 12au7 in this amplifier before starting the mods.
I use here when I don't need much distortion 12au7. But some friends use 12ay7 too and them liked these two tubes.
[/B]
Thanks! yesterday have made the first 2 mods, bypass R6 & C6
and put C2= 10u, the sound mellowed a bit, before make other mods in the circuit i want to try the change of the 12AX7 with
AU7 and AY7 (have to bought them), what is the valve yiu suggest to change, the first (input) or the second?


Quote:
Originally posted by 45


12AY7 has no european equivalent in my knowledge.
Other american equivalts of 12AY7 are 6072, 6072A.

12AU7 is the american equivalent of ECC82.

ECC82-12AU7 exist in several versions: E82CC, ECC802S, 12AU7A, 5814 and some other less common.

However 12AY7, 12AU7 and 12AX7 all have the same pin-out and filament supply requirements.

Cheers!
Thanks a lot
After your advises guys i googled and discovered an interesting program to calculate the gain with the various ECC81/2/3

http://www.audiocostruzioni.com/a_d/.../tube-math.htm

then this site is very useful too:

http://thetubestore.com/gainfactor.html

here compare the gain of the varoius type and compare various brand too!:

http://thetubestore.com/12ax7review.html
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Old 22nd December 2008, 02:03 PM   #18
45 is offline 45  Italy
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Packman, kwowing the gain of devices is useful as line of guide.

However a guitar amp has to produce a sound and not re-produce with the best possible fidelity a recorded sound.

So, I think the best way is : "plug them in and listen to what comes out!"


Cheers,
45
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Old 22nd December 2008, 02:26 PM   #19
45 is offline 45  Italy
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An important question to me.

If you amp is in good condition, I think it is not a good idea to heavily modify it because it could loose all its value.

Just replacing the tube will not compromise the historic value of the amp as you can always fully restore its original configuration.

Cheers,
45
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Old 22nd December 2008, 10:05 PM   #20
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Quote:
Originally posted by 45
An important question to me.

If you amp is in good condition, I think it is not a good idea to heavily modify it because it could loose all its value.

Just replacing the tube will not compromise the historic value of the amp as you can always fully restore its original configuration.

Cheers,
45
It's sounds like it is a re-issue amp, so one needn't be too concerned about historic value in that case.
One does need to be careful, though, since most of the reissues are built on pcb and don't always hold up well to a lot of soldering and swapping of components.
Cheers
John
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