DIY Audio Projects Forum
 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 01 Nov 2014, 07:21

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: GU29 Amplifier
PostPosted: 03 Jan 2013, 04:43 
Offline
User avatar

Joined: 27 May 2012, 07:21
Posts: 26
Location: Romania
Hi everybody!

After a nice Single Ended with Russians 6P3C and 6N2P, I would like to start another tubes project, another amplifier, but this time with the Russians double tetrodes GU29, that I have a NOS pair. I like very much the shapes of this tetrode :)
I want to know if somebody has made this kind of amplifier and I want to try a good and tested schematic, whatever if it is Single Ended or Push Pull, but simplest as possible, with schematic, of course, of power supply. I have a few schematics, but I'm not sure how reliable are.

Thanks a lot!

_________________
In TUBES we trust!


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 03 Jan 2013, 10:20 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 2418
Location: Arizona, USA
Hi, I have not used the GU29s ,but did use the GU32s in a "oddwatt" circuit. At first I tried to use just one tube per channel in push-pull ultra linear class A mode. The common cathode made it impossible to balance the tubes in the same way as the other amps, so I used the variation similar to the Poddwatts with a CCS in the cathode circuit and variable positive voltages to the grids. idle current was measured across 1 ohm resistors in the anodes. Using roughly 5 volts DC (variable) fed to the grids through a high value resistance on the individual grids I could get them to balance. A second amp I used the 32s in push-pull U/L parallel with two tubes per channel with the individual sections in each tube tied together. Balance was then by the 25 ohm pot I use in nearly all similar amps. In neither amp did I get as much output as I hoped for. I don't recall the values right now, but it seemed to be about 5-6 watts in the one and about 10 in the other. The sound quality of the amps was not up to what I would consider hi-fi standards. Since these are RF tubes, I suspect that the response was non-linear in the power range I desired and was causing a lot of harmonic distortion. Since both amps were significantly below the performance level I felt minimal I discarded the project.

For a general purpose amp they may be suitable. The tubes do look cool though. A pair of EL84s will run circles around them for audio though and you don't need to find the anode clips or funky sockets.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 03 Jan 2013, 11:07 
Offline

Joined: 11 Oct 2011, 19:39
Posts: 180
Here you go. I forgot where I got this from, but I did buy the tubes to build it but don't have the iron right now. If you use the circuit, let me know how it turns out.


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.



Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 03 Jan 2013, 11:32 
Offline
User avatar

Joined: 02 Mar 2009, 12:41
Posts: 806
Location: Vänersborg, Sweden
Can you share a schematic for the 6P3C? I have some left from my Priboj amp and even though the tube isn't the most reliable tube, it's still awsome to be able to do something with this dual power tetrode.

However, the 829 is said to be very much like a dual 6L6 so you could either start with a schematic for 6L6, with the halves either separately - one half for each channel - or parallelled.
I will finish an 832-SE when we get home from the States. I am using a single 832 (using 6V6 schematics) and, as there's only a single cathode connection for both halves, I have halved the R and doubled the C. As driver a 6SL7, resulting in a two-tube amp.

_________________
Magnus

“If you don't know where you are going, any road will get you there.”
―Lewis Carroll


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 04 Jan 2013, 01:13 
Offline
User avatar

Joined: 27 May 2012, 07:21
Posts: 26
Location: Romania
Thanks to all for yours early replys.
I still want to make the GU29 amplifier, and I'm waitin' for another schematics and opinions.

Soundbrigade, there is a 6P3C and 6N2P amplifier schematic.
Best wishes!


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
In TUBES we trust!


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 04 Jan 2013, 08:28 
Offline

Joined: 05 Jun 2012, 13:10
Posts: 176
Location: Darboy, WI, USA
What is C5 doing in the above circuit? Feedback or filtering?

_________________
Thanks,
Ross in Wisconsin


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 04 Jan 2013, 16:58 
Offline
User avatar

Joined: 05 Nov 2010, 21:07
Posts: 660
Location: South East US - Tennessee
g2 bypass? ;)
Seen this arrangement a few times. The one that comes to mind is the Fender Champ 5F1. Drawn a little different, but it's the same arrangement. I was just being silly about a g2 bypass, however, given its value....... Otherwise, it's just a small filter.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 28 Jun 2013, 04:57 
Offline
User avatar

Joined: 27 May 2012, 07:21
Posts: 26
Location: Romania
My GU29 PP unfinished amp:


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
In TUBES we trust!


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 28 Jul 2013, 23:46 
Offline
User avatar

Joined: 27 May 2012, 07:21
Posts: 26
Location: Romania
Testing, testing, 1, 2... :headphones:


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
In TUBES we trust!


Top
 Profile  
 
 Post subject: Re: GU29 Amplifier
PostPosted: 29 Jul 2013, 00:01 
Offline
User avatar

Joined: 05 Nov 2010, 21:07
Posts: 660
Location: South East US - Tennessee
Cool!

I make one little suggestion.... Some clear heat shrink on the anode connections - for safety's sake. Sorry, jus the way I am. I don't like exposed lethal voltage terminals..
Otherwise, very cool looking. Almost "sci-fi"ish -- imagine perspective shooting: tube looks 50' tall with average height humans standing in awe of the tube's glorious power.. :)

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

Science without religion is lame, religion without science is blind. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board
Current project: 6V6 "pseudo Champ" prototype
Still to come (On hold): 6CG7/12AX7 Guitar amp (modified FireFly)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 26 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: johan-71, kitchi, Yahoo [Bot] and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Opamp Projects :: DIY Phono Projects :: DIY Cable Projects :: HI-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy