DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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 23 Feb 2018, 13:07

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 103 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 11  Next
Author Message
PostPosted: 24 Jun 2011, 22:53 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1394
Location: US Pacific Northwest
Well, I've got about 50 hours on this amp now and it sounds great. Highs are very crisp, the mids are smooth, and the bass is mellow but very detailed. As I said above, perfect for soft vocal jazz.

There is one thing I don't quite understand yet. After about 6 to 8 hours, the Hammond power transformer becomes almost too hot to touch. I would estimate it's external temperature at about 120˚F to 125˚F. The first cap after the 5U4 is only a 32µf so the conduction angle should be long enough that I don't get this much core heating. The chokes and output transformers are nice and cool. Now that I think about it, the Hammond power transformers on my headphone amps do the same thing. :confused:

Does anyone else have this experience with Hammond power transformers? Is this just typical of their transformers? Any experiences other people have with their power transformers would be greatly appreciated.

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
PostPosted: 24 Jun 2011, 23:02 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2161
Location: Chilliwack, BC
Hammond power trannies get HOT.

40-45C rise above ambient is normal for every one I've used.

Edcor's run at 25-30C rise at full tilt (depending on core size). Why I've defected to them ;)

IR thermometer shows 64C as typical on my preamps with Hammonds.

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 13 Aug 2011, 21:54 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1394
Location: US Pacific Northwest
For anyone interested, there is now a more complete write up on this amp located on my webpage at http://www.cascadetubes.com/Tube_Site/The_6V6_Lacewood_Amp.html.

As always, comments, questions, criticisms, or just random thoughts are more than welcome. :D

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
PostPosted: 14 Aug 2011, 05:01 
Offline
User avatar

Joined: 14 Feb 2010, 13:13
Posts: 663
Location: Lisbon, Portugal
Suncalc wrote:
...
Does anyone else have this experience with Hammond power transformers? Is this just typical of their transformers? Any experiences other people have with their power transformers would be greatly appreciated.

I also have a Hammond power transformer in one of my FM tube radio. The transformer gets hot in comparision with others i have used before, and it´s working well between his limits.

So I question their quality, they are converting to much energy into heat!

Cheers,
Miguel


Top
 Profile  
 
PostPosted: 15 Aug 2011, 21:12 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4530
Location: Winnipeg, CANADA
Hey Matt, great write-up. I love the prototype PS!

Cheers

_________________
[ 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: 16 Aug 2011, 08:08 
Offline

Joined: 18 Jun 2010, 12:46
Posts: 284
Location: Northern VA
The hammond power transformers I have used also run hot, it's typical(for hammond)


Top
 Profile  
 
PostPosted: 16 Aug 2011, 14:03 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3552
Location: Arizona, USA
Hi, Very nice build and a good project for others. :thumbsup: The initial thoughts on DC heaters are pretty much valid. In my experience they are not needed for projects with a S/N of 80 db or less. 80 BTW is rather quiet. I generally design to hit -90 db so in that case they do help. All the effort can be wasted if the particular tubes and and brands of tubes don't hold up their end. I just sent back 6 new production Mullard 12AX7s as they were noisier than the standard JJ ECC803S. The difference was between 2.5 and 3 db per tube. Maybe a bad batch... then again maybe not.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 16 Aug 2011, 17:48 
Offline
User avatar

Joined: 14 Feb 2010, 13:13
Posts: 663
Location: Lisbon, Portugal
I small add-on...

In my opinon the JJ tubes have a wonderful sound.

Built with new tecnologies and the relation between price / quality is unbeatable.

Nice project! :)


Cheers!


Top
 Profile  
 
PostPosted: 16 Aug 2011, 21:48 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3552
Location: Arizona, USA
Hi, I use JJ tubes as a first choice in my projects and the commercial stuff I do uses them when they are available as well. I love the JJ Blue Glass EL34s and the Blue Glass KT88s. I'm sure the glass doesn't alter the sound in any way, but they may be selecting the best tubes to put in the blue glass. I heard that they make them in red glass as well but have never seen them. That might be really cool.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 16 Aug 2011, 22:24 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1394
Location: US Pacific Northwest
These JJ 6V6s were brand new when I put them in the amp. They started off a little bright for my tastes. However they really surprised me because in only a few hours they really started to even out. After about 100 hours they were very smooth with what appears to be a very even response. After several hundred hours now on this amp I can't imagine using anything else. I just really love their sound.

I even swapped in a NOS GE 7408 into one channel to compare directly. After several hours I put the JJ back into that channel. There was no contest.

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 103 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 11  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 12 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 / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy