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A Very Compact Hybrid Amp - Page 56

post #826 of 2213
olblueyez - The tube impressions you post here... Are they *in* a CTH?

If not, perhaps a dedicated 12AU7/6922 variant impressions thread is in order?
Though much of your impressions may apply to the tube behavior in CTHs too... E.g. for the tubes I own & have used in CTH & you've commented on, my impressions are similar.

Bringing this up because what amp you are using them in can be a big factor. Alex goes to great lengths to get things right for the tubes in his designs & this very much influences things.

And I *think* we are trying to keep this thread to experiences during build, any debugging, etc. There is a tube + tweak thread and perhaps there should be a general CTH impressions thread too (as it's hard for others to find CTH impressions scattered about). IMNSHO of course
post #827 of 2213
x2
post #828 of 2213
Quote:
Originally Posted by cfcubed View Post
olblueyez - The tube impressions you post here... Are they *in* a CTH?

If not, perhaps a dedicated 12AU7/6922 variant impressions thread is in order?
Though much of your impressions may apply to the tube behavior in CTHs too... E.g. for the tubes I own & have used in CTH & you've commented on, my impressions are similar.

Bringing this up because what amp you are using them in can be a big factor. Alex goes to great lengths to get things right for the tubes in his designs & this very much influences things.

And I *think* we are trying to keep this thread to experiences during build, any debugging, etc. There is a tube + tweak thread and perhaps there should be a general CTH impressions thread too (as it's hard for others to find CTH impressions scattered about). IMNSHO of course
Quote:
Originally Posted by smeggy View Post
x2
Next time use a private message.
post #829 of 2213
I PMed olblueyez about this misunderstanding.... No offense intended, sorry if some was taken. Like his contribs here & elsewhere on the forums....

Just wanted some order in the various CTH threads (Edit: also to make it easier for people to find things w/o always having to resort to search, esp for noobs). It's the software developer in me I guess
post #830 of 2213
[DELETE]
post #831 of 2213
Got my kit today, USPS butchered the box somewhat but everything inside survived just fine. Now it's time to have fun
post #832 of 2213
Quote:
Originally Posted by cfcubed View Post
I PMed olblueyez about this misunderstanding.... No offense intended, sorry if some was taken. Like his contribs here & elsewhere on the forums....

Just wanted some order in the various CTH threads (Edit: also to make it easier for people to find things w/o always having to resort to search, esp for noobs). It's the software developer in me I guess
Its all Good!
post #833 of 2213
Quote:
Originally Posted by wiatrob View Post
Good to hear it's not getting too hot - the large hole around the tube should help. I'd still do a hole over the 24V reg, but if it's staying cool - you're probably fine.

What tubes are you using?
I've also found the switchmode reg gets relatively hot, but I don't think enough to worry about. I'm keeping an eye on how hot the case is getting, just hope I don't need to drill anymore holes.

I have a bunch of tubes I've been trying. Currently trying a GE 12AU7 short grey plates, but also have a Toshiba 12BH7A, Sylvania Long Plate 12AU7A, Mullard and MiniWatt 12AU7, Electro-Harmonix 12BH7-EH and a 6N1P-EV from the group buy.

Any suggestions which would be the best to try? I'm a bit of a tube noob..
post #834 of 2213
try them all!
post #835 of 2213
Quote:
Originally Posted by nux View Post
I have a bunch of tubes I've been trying. Currently trying a GE 12AU7 short grey plates, but also have a Toshiba 12BH7A, Sylvania Long Plate 12AU7A, Mullard and MiniWatt 12AU7, Electro-Harmonix 12BH7-EH and a 6N1P-EV from the group buy.

Any suggestions which would be the best to try? I'm a bit of a tube noob..
The best tube will depend on what headphones you have, what music you like and the sound you are looking for. If I had a Mullard to try though that would be my pick, also really like the 6N1P and other Russian tubes I have tried, just remember to switch the heater to 6.3V.
post #836 of 2213
Well, my CTH build problems continue to persist and multiply. I got the parts from Bill (Thanks Bill). The first thing I did was replace R1E and R2E to the BOM parts, because I didn't have correct values when I changed to the updated BOM earlier and I had fashioned them out of two resistors in series to get the right figure. At first, I thought this had solved the e12 problem, as I was able to play through a song or two without the relay tripping. So, I cased it up without changing any transistors. Of course after I had, the problem reappeared. Some time after taking it back apart to address this, the wall wart I was using died. I located another power supply, and now the tube is not lighting. I am now getting @ 108v on TB+ and this same amount on pins 1 and 6. OG is at 12v and ICP is ok. What did I do now?
post #837 of 2213
tacitapproval. My 2nd build is having some issues as well, and I'll be looking at it. Can you measure the DC offset, and keep an eye on it. What I mean is power it on, measure the DC offset (before the e12 if you can). Watch both channels or find the one that is tripping the e12.

What I am finding with mine is that the DC offset climbs with time, on the right channel. It bounces around, albeit slowly, but it is significantly higher than the left. The left is at a few mv at most.

I was just wondering if your problem is similar.
post #838 of 2213
Quote:
Originally Posted by holland View Post
What I am finding with mine is that the DC offset climbs with time, on the right channel.
What kind of time frame are you seeing typically?
post #839 of 2213
Thread Starter 
Quote:
Originally Posted by tacitapproval View Post
Well, my CTH build problems continue to persist and multiply. I got the parts from Bill (Thanks Bill). The first thing I did was replace R1E and R2E to the BOM parts, because I didn't have correct values when I changed to the updated BOM earlier and I had fashioned them out of two resistors in series to get the right figure. At first, I thought this had solved the e12 problem, as I was able to play through a song or two without the relay tripping. So, I cased it up without changing any transistors. Of course after I had, the problem reappeared. Some time after taking it back apart to address this, the wall wart I was using died. I located another power supply, and now the tube is not lighting. I am now getting @ 108v on TB+ and this same amount on pins 1 and 6. OG is at 12v and ICP is ok. What did I do now?
Let's just try to fix one thing at a time. Measure with respect to SG what are voltages at pins 4 & 5 on the tube socket?
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
Reply
post #840 of 2213
0v on pin 4 and 5.
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