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matejsirk 2nd January 2012 07:41 PM

GU50 Prototypes
 
5 Attachment(s)
Some time ago, me and friends decided that we make a few prototypes with GU50. The idea was to test as many different combinations. For input tube we decided for 6SN7, 6SL7, 6N1P, 6N23P, 6N6P, D3a, 6C3P, ECC83, ECC85, ECC81.

We made some SE prototypes, one of the PSE and the PP one. As the input tube we test: D3a, 6C3P (the best two), 6N23P, 6SN7, 6N6P (also very good - not enough gain), ECC83, ECC85 (not so good). The project is continuing. Now I'm working on the development of housing.

We found that the GU50 is one of the best, for me better than EL34 or EL84.

A couple more pictures of prototypes:

fabioab 8th November 2012 12:25 AM

Hi, my prototype is a mix of Fender AB763 with 12Ax7 as phase inverter, and two Gu50 at the power.

ry50 - 80W - YouTube
Only volume pot.

Almost finished!

Wavebourn 8th November 2012 12:58 AM

Quote:

Originally Posted by matejsirk (Post 2843752)

We found that the GU50 is one of the best, for me better than EL34 or EL84.

Me too. :D

Also I found that it is better than that 6L6 clones like KT-88.


Here are my prototypes:

http://wavebourn.com/BAF/russian_glassware.jpg

http://wavebourn.com/images/pyramid/Pyramid-V-M.gif

http://wavebourn.com/images/pyramid/...-VII-front.gif

http://wavebourn.com/images/pyramid/Pyramid-VII-M-1.gif

Junm 8th November 2012 05:05 AM

nice work sir wave,

I'm also planning to do a PP gu50 with 6n6p drivers or 6n1p....any schematics suggestion for a 50w amp?

Jaap 8th November 2012 07:45 AM

Quote:

Originally Posted by matejsirk (Post 2843752)
Some time ago, me and friends decided that we make a few prototypes with GU50. The idea was to test as many different combinations. For input tube we decided for 6SN7, 6SL7, 6N1P, 6N23P, 6N6P, D3a, 6C3P, ECC83, ECC85, ECC81.

We made some SE prototypes, one of the PSE and the PP one. As the input tube we test: D3a, 6C3P (the best two), 6N23P, 6SN7, 6N6P (also very good - not enough gain), ECC83, ECC85 (not so good). The project is continuing. Now I'm working on the development of housing.

We found that the GU50 is one of the best, for me better than EL34 or EL84.

A couple more pictures of prototypes:

Schematics ?

fabioab 17th November 2012 11:20 PM

6 Attachment(s)
Hi, I would state some "strange" behavior of my ampli.
When I cranck (or close cranck) the volume pot, it starts a riiiiiiizzzzzzz. Obvioulsly the amplifier is totally saturated and crunched. It happens without the guitar plugged too.

Some Ideas what could cause this effect. The circuit was based in the Fender 6G8 circuit end AB763. The PI tube is a 7025 as in 6G8.

Thanks a lot who try give-me an explanation!
I'm sending some pictures.
FAB

fabioab 19th November 2012 10:12 PM

nobody has some idea ???

Wavebourn 19th November 2012 10:31 PM

I have an idea. It is probably the result of some parasitic feedback, either capacitive between close input and output wires, or some common wire (so called ground) is soldered in the wrong place.

fabioab 19th November 2012 10:40 PM

Thanks Wavebourn, some day I will try fix the problem! But I would like to have some idea about what could cause the problem.
For the time being, I'm playing to have some fun!
Cheers FAB

Alphy 28th November 2012 07:32 PM

Hi Wavebourn, as I pm'd you months ago, still waiting for your 30+ Watts design with this endvalve :).


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