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 24 Nov 2017, 04:18

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 29 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
PostPosted: 09 Nov 2017, 14:05 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
mwhouston wrote:
For some strange reason on some tracks there is a crackling sound. It is appears to be distortion and appears to follow passages of heavy bass.


I bet it's going unstable as DC blocking happens on peaks. Look for "fuzzy tips" on a scope.

Cheers!

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


Top
 Profile  
 
PostPosted: 09 Nov 2017, 17:23 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
Geek wrote:
mwhouston wrote:
For some strange reason on some tracks there is a crackling sound. It is appears to be distortion and appears to follow passages of heavy bass.


I bet it's going unstable as DC blocking happens on peaks. Look for "fuzzy tips" on a scope.

Cheers!


How do I fix it.

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 09 Nov 2017, 18:42 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
I have mentioned in this thread and one other that this little HP amp was showing some distortion. Well it appears my Pi music server and HDMI audio ripper was putting out over 2V thus overdriving the E88CC which is biased at 1.5V. By dropping the input volume by 70% coming out of the Pi and bring up the volume on the Sanctum I now have distortion free listening.

Funny how on classical music I never heard a single note of distortion but on some jazz tracks and rock tracks it would appear. I'm going to upgrade the tranni then all should be fine.

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 10 Nov 2017, 01:42 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
mwhouston wrote:
Geek wrote:
mwhouston wrote:
For some strange reason on some tracks there is a crackling sound. It is appears to be distortion and appears to follow passages of heavy bass.


I bet it's going unstable as DC blocking happens on peaks. Look for "fuzzy tips" on a scope.

Cheers!


How do I fix it.


Well, first verify if that is what's happening.

To me, R4 is too small... significantly. I'd use 2.2K to 10K. I'd add one in the output tube grid, too.

Cheers!

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


Top
 Profile  
 
PostPosted: 10 Nov 2017, 02:58 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
I'll take a look. Thanks.

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 10 Nov 2017, 06:44 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
Sounds OK now I have lowered the input voltage. But have to agree with you 33ohms is a silly low figure. 330ohms makes more sense.

Also I have been able to raise the volume of the Pi server to 80%. Stills sounds OK. Suposedly the Pi server doesn't bit strip when using its volume control. It has a 32bit software volume control.

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 14 Nov 2017, 07:16 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
A couple of observations;

The power tranni gets awful hot. To help ease this if dropped the HT to 147V from 157. Less current from the tranni. I'm still using a 6V E83CC Gold Lion gold pin which is slightly overtaxing the 2.5A filament voltage. I was running the driver tube on its own filament tranni but the main power tranni got just as hot. We will see if it holds out.

By far the best sounding driver tube compared to a new Sovtek 12AX7 and a well worn Ozzie Miniwatt 12AU7 is the Genelex Gold Lion (as mentioned above). Fast, detailed, rich and revealing. They are a $80 tube landed in Oz so at that price they should be good.

Best power tube is a lightly used (tested 105) RCA 6AS7. I am yet to try the NOS early Svetlana wing C but the GE 6080 didn't get me excited.

I measured the -3db point and it was about 10hZ but calculations suggest about 50hZ into 32ohms. The output cap is a NP 100uf snubbed by a 220nf poly. I have a couple of 47uf caps I may add to the output caps to bring down the the lower 3db point. But the bass sounds full enough as is.

Very pleased with the sound and look. Just hope the power tranni holds out.

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 14 Nov 2017, 13:56 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
I was just discussing hot power trannies with a customer last week. I explained about "degrees C. rise above ambient" and when he measured the transformer hot vs. his room temp, it was still 10C. under its rated rise in the spec sheet.

That's the thing I'd be concerned over rather than the actual temp ;)

Cheers!

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


Top
 Profile  
 
PostPosted: 14 Nov 2017, 16:05 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4756
Location: Australia
Does Hammond publish temp ratings for thier trannies?

_________________
Projects: "Tutu" - 150W Tripath T3 monoblock | "Silver Supreme" - 6L6GC-12AT7 SE UL power amp | "retro-4040" - 40W Chip amp LM3876T
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 14 Nov 2017, 19:47 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1363
Location: US Pacific Northwest
From the Hammond Power Solutions website:
Quote:
Troubleshooting: Overheating
Transformer insulation is generally rated for 220°C but may be lower for some designs including control or encapsulated. Standards permit the temperature of the transformer enclosure cover to be 65°C over ambient. When temperatures exceed the rating for the insulation system or enclosure, overheating occurs.

Burned, darkened or damaged insulation may be apparent along with a burnt smell. The hottest part of a transformer is the coil near the top of the core. Energized transformers should not be touched. If the insulation is damaged or smoke is visible, the unit may need to be returned for testing and replaced or repaired.
Note that this is for industrial power transformers not necessarily tube amp power transformers. I have just sent an email to Hammond inquiring about the temperature rise specification for their "Classic" series power transformers. With luck they will respond with their actual specifications for temperature rise. When they do, I will forward the information along.

I've long had questions concerning the temperature rise of Hammond Classic transformers. Maybe we'll finally get some solid engineering data.

_________________
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  [ 29 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Bing [Bot], poty 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