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 28 Jul 2014, 17:30

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 1194 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7, 8, 9 ... 120  Next
Author Message
PostPosted: 29 Dec 2008, 00:17 
Offline

Joined: 27 Dec 2008, 04:48
Posts: 25
Location: QLD, Australia
Hmmm, I went ahead and the result is excellent. I only modified the power amplifier section, the 6N2 and 6N1 valves are still being used to drive the output valves, but only the first half of each 6N1 phase splitter is being used. Any doubts I initially had about this unusual and simple circuit are completely dead and buried, from initial listening there is now deep bass I had not heard before and the clarity at all frequencies is improved. Very, very nice. Thanks Bruce.

Will post some pics later.


Top
 Profile  
 
PostPosted: 29 Dec 2008, 07:58 
Offline

Joined: 27 Dec 2008, 04:48
Posts: 25
Location: QLD, Australia
An example of a heatsink for the LM317 that is on the small side, it works, but is pushing it. Some pics:
Image
Image
Image
Image
I will make something more substantial when I get back to work.

Bruce, I am not sure that cathode bypassing of the LM317 regulator is not possible:
http://www.glass-ware.com/tubecircuits/ ... ing_2.html

Ian.


Top
 Profile  
 
PostPosted: 29 Dec 2008, 18:26 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4250
Location: Winnipeg, CANADA
Hi Ian, glad that worked out for you. How did you mount the potentiometer to the chassis?
Cheers,
Gio

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 29 Dec 2008, 19:04 
Offline

Joined: 27 Dec 2008, 04:48
Posts: 25
Location: QLD, Australia
Gio, I used some non-acidic silicone (Dow Corning 3145RTV Gray) which holds the pot nicely but can also be removed without breaking things, if required.


Top
 Profile  
 
PostPosted: 30 Dec 2008, 15:13 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 2329
Location: Arizona, USA
Hi Ian, Bypassing the cathode on one of the self inverting output stages defeats the inverting process as the second tube gets its drive essentially through the cathode. On a conventional amp with the phase inversion done earlier and each tube driven in a typical fashion it may be possible to use a bypass cap across the 317. I can not determine exactly what the implications would be of such an arrangement. More gain probably, distortion ?, would it still be fully class A ?, I don't believe there would be any harm in trying it. Let us know if you do.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 30 Dec 2008, 16:24 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 3735
Location: Australia
gofar99 wrote:
Second photo

Bruce,
Just took another look at your monos. Yes they sure do look good. What do you think is your best build so far for this configuration? I'm still waiting parts from Edcor before I can start me SEs.

_________________
Projects: "Parley" - Tube preamp with Pass B1 buffer | "VoXConcentriC" - Beyma high efficiency 12" speakers | "Black Lace" - all Ozzie tube 6V6 Power amp - old school
Website: [ retro-thermionic ]


Top
 Profile  
 
PostPosted: 31 Dec 2008, 06:29 
Offline

Joined: 27 Dec 2008, 04:48
Posts: 25
Location: QLD, Australia
gofar99 wrote:
Hi Ian, Bypassing the cathode on one of the self inverting output stages defeats the inverting process as the second tube gets its drive essentially through the cathode.

Bruce, I'm a newbie so I don't really know much. I did try a 1uF cap across the 10 ohm resistor since the LM317 datasheet says it will improve transient response (as a voltage regulator, but maybe not as a current regulator). The result was not good, a bit less clarity, less deep bass, and a bit less gain. So I'll leave the experimenting at that. I reckon this is your baby so you know best. Probably the best thing I can do is order a couple of 5751's and make it a complete OddWatt conversion :) The new Svetlana's are selling for a reasonable price.

Thanks,
Ian.


Top
 Profile  
 
PostPosted: 08 Jan 2009, 18:08 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 2329
Location: Arizona, USA
Hi Ian, There are a number of good 5751s out there. The tube type is a good nine pin sub for the octal 12/6SL7s. I have had good results with Russian made ones. If anyone out there tries some of the premium or NOS ones, I'd like to hear what their impressions are.

The protype pair of amps now has around 500-600 hours on them with about 60% of the time with the JJ KT77s and the rest with the Gold Lion KT88s. I like the sound of both although they do sound different. The 88s are more "gutsy" (good high tech term there!) and the 77s seem more refined. No problems with the amps. If anyone is trying to build them out there and can't find the thermal delay "tubes" make a post here. I have a new alternate circuit you can try using a 6H6 dual diode tube in place of the 6NO30. A single transistor circuit is also available for those who have need of it. As a last resort you can always use a B+ switch.

Good Listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 08 Jan 2009, 19:48 
Offline

Joined: 26 Aug 2008, 20:57
Posts: 415
Location: Atlanta
I used to use GE Triple mica black plate 5-star 5751s (whew thats a mouthful) in my Onix SP3 and they were a wonderful tube. Very detailed but with a warm, smooth sound. They were a hair better than Mullard CV4024s.

My first 5751s were Sovteks and they were ok, especially for the price, better than stock Chinese ax7s, more detailed, more full sounding but not anywhere near the level of the GEs.


Top
 Profile  
 
PostPosted: 20 Jan 2009, 11:49 
Offline
Project Author
User avatar

Joined: 14 Oct 2008, 17:35
Posts: 901
Location: Dartmouth, Nova Scotia
Hey there Bruce, if you don't mind I would like to see that 6H6 timer circuit as I have 3 brand new ones made by Rogers and have nothing better to do with them.

I am slowly collecting the parts for my williamson build, I have all the transformers and about 50% of the components needed to build this beast. I ordered a couple of LM317HV To-3 regulators for the CCS, so I should have no problems using KT66's, 88's and 77's, but the first tubes to be used are my 6L6WGC's made by Sylvania.

The only bad thing about this build is its mass, I may need a pickup truck just to transport this thing, but I will be satisfied with it as long as it works well and sounds well, I will compare it to my true williamson amplifier after it is built.

_________________
My Mini 12AU7 Tube Preamp, Pioneer SX-D7000, JVC XL-V221BK, JBL L80T, DCM TF700


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1194 posts ]  Go to page Previous  1 ... 3, 4, 5, 6, 7, 8, 9 ... 120  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 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