SSE very quiet - Page 2 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Tubelab

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 29th July 2014, 06:57 PM   #11
diyAudio Member
 
denny3249's Avatar
 
Join Date: Jun 2012
Location: The frozen tundra of Cheeseheadland....GO PACKERS !!!
Quote:
Originally Posted by adrianbaugh View Post

By the way, while I'm buying more parts, can anyone suggest a good (preferably UK based) source of 47uF 500V electrolytics? I couldn't find one before so there is a 68uF in there at the moment which is too big really.
A 33u/500v will work if you can source one in the UK.... It's what I used. George states 22u-47u/500v can be used as C1 ...
  Reply With Quote
Old 31st July 2014, 07:32 AM   #12
diyAudio Member
 
Join Date: Sep 2013
Thanks, I'll see if I can find a 22 or 33u.

I found the main problem (hopefully)... I had installed the 10M45s the wrong way round. That's now corrected, with new devices, but the problem still exists - still very quiet, with a signal very faintly audible if I put my ear to the speaker. What other components am I likely to have damaged having those the wrong way round? I know the OPTs are good by the way, I checked them with a 12V 50Hz signal to the primary and got sound out of the speaker.
  Reply With Quote
Old 31st July 2014, 06:19 PM   #13
diyAudio Member
 
Join Date: Sep 2013
I've discovered something else. If I remove the driver tube (I've tried a CV4024, also a 12AU7 I had lying around), switch on and then insert the driver tube once everything else is warmed up, the volume level increases from nothing for a few seconds, becoming quite clear and audible (though not as loud as it should be given the source is turned right up) before falling away to the same extremely low level as before and staying there. Any suggestions, anyone?
  Reply With Quote
Old 31st July 2014, 07:14 PM   #14
diyAudio Member
 
jpjones3318's Avatar
 
Join Date: Jan 2011
Location: Boulder, CO
Is the driver conducting? What's the voltage drop across R13 and R23?
  Reply With Quote
Old 31st July 2014, 07:37 PM   #15
diyAudio Member
 
Join Date: Sep 2013
Quote:
Originally Posted by jpjones3318 View Post
Is the driver conducting? What's the voltage drop across R13 and R23?
Across R13 there is 0V dc, a few millivolts ac. (Same with R23.) DC voltages at the CCS pins are as follows: G - 0V, A - +475V as expected, K - 0V. When I touch the multimeter probe to the end of R13 there is loud hum audible from the speaker, it seems to be picking up mains hum via the probe.

So does this mean my second pair of CCS are defective? (or more likely I've broken them somehow - I hate handling semiconductors...)

Regards
Adrian.
  Reply With Quote
Old 31st July 2014, 10:20 PM   #16
diyAudio Member
 
jpjones3318's Avatar
 
Join Date: Jan 2011
Location: Boulder, CO
With the driver tube out you should see the same voltage at A, K, and G. Make sure R10/20, R13/23, and R19/29 are not open and measure correctly. If they do, then it seems the CCSs are bad, though it's unusual for both to be bad unless they were purchased from a poor source or took way too much heat during soldering.
  Reply With Quote
Old 31st July 2014, 10:38 PM   #17
diyAudio Member
 
Join Date: Sep 2013
With the driver tube out, both CCS measure 0V at K and G and +475V at A. All the resistors measure correct so it looks like I got duff CCSs. They're difficult to get in the UK so I took a chance on eBay. I've now found a different supplier so I'll see how the new ones work out, they should arrive on Monday. Thanks for your help & I'll post an update once the new semiconductors are fitted.
  Reply With Quote
Old 4th August 2014, 09:05 AM   #18
diyAudio Member
 
Join Date: Sep 2013
The new parts have arrived. Before I fit them, a question about B+: when switching the amp on B+ increases to in excess of 500V for a few seconds (from memory about 540V) before settling back down to 475V. Could this be the cause of failure of the previous CCSs (and is it a problem for the electrolytics, which are 500V rated)?

I don't want to burn out another pair of CCSs if there's a power supply problem I need to sort out first!
  Reply With Quote
Old 4th August 2014, 12:08 PM   #19
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
The power supply is OK. It is normal for the B+ to surge on initial turn on, and your 500V electrolytics probably are rated for a 550V surge.

The voltages you stated around the CCS chips are wrong. This could be where the problem lies. You can test the circuit without the chips.

The 12AT7 will work with a plate load resistance in the 33 to 47K ohm range in place of the CCS. The performance will not be as good as a CCS (lower gain, higher distortion) but you can verify the rest of the circuit.

You can do this by jumpering the CCS and replacing the 10K 2 watt resistor with a something between 30K and 51K that is rated for 2 watts.

You can also leave the 10K in place and temporarily solder a resistor (20K to 33K) between the 10K and the 12AT7 plate (in place of the CCS chip).
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 4th August 2014, 05:55 PM   #20
diyAudio Member
 
Join Date: Sep 2013
Success! (Progress, anyway...) I rigged up a 2W 30K resistor between the 10K and plate on one of the 12AT7s and that channel now works fine (and loud!) So... I'm guessing that narrows down the problem to a bad pair of CCSs, either through just chance or mishandling. I'll try fitting a new pair (carefully!) and see if that fixes things.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Auricaps in SSE and SSE as a guitar amp. DanP Tubelab 5 12th July 2010 09:20 AM
How quiet is dead quiet? pchw Tubes / Valves 36 22nd November 2007 04:36 AM
How quiet will it be? MMicke Chip Amps 8 12th July 2003 08:26 PM
Too quiet! grataku Everything Else 14 14th February 2003 04:39 PM
Quiet Fans merbert Parts 4 2nd May 2002 08:22 PM


New To Site? Need Help?

All times are GMT. The time now is 06:46 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2