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SOHA II Builders Thread - Page 97

post #1441 of 1686

i will go back and check.  i got a nudging feeling i got the wrong VA for the transformer. I might have gotten 15VA thus for each of the secondary its only 500mA. if thats the case, i dont know what else to say but sorry x 10 in having my carelessness for wasting your and regal's time in helping me to troubleshoot. 


Edited by Cloud - 9/12/10 at 6:50pm
post #1442 of 1686
Thread Starter 

If that's the case, no apologies at all are necessary. I'd just be happy that you can get the amp back working again with a newer better transformer.

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #1443 of 1686

turn out that the transformer was as spec. I removed all the wiring and reconnected them and TB+ was back to 100V+. good news!

 

however, another problem surfaced. e12 keeps turning on and off, on and off in a cyclic pattern. When its on, there is alot of distortion

 

Difference between TB+L and TPL and TPR and TB+R is around 24V

 

R10L and R10R measures 220mv across

 

Changed a pair of tubes, no difference.

 

Where should i look into for the new problem?

post #1444 of 1686

So I've been using this amp for some time now and it's great, but I've always wondered what is it's max output using 12AU7's?

How would I go about measuring this this?

post #1445 of 1686

Just recently found this awesome amp, and I want to give it a try.

I am new to head-fi, and want a good starter amp. I love the idea of a DIY project. So this is right up my alley.

I have read the entire thread, but have overlooked some crucial informasion by all the reading.

Do the kit from Glass Jar Audio come with a 110vac or 220vac transformer?

I have contacted Glass Jar Audio trough their website, but haven't recieved any answer yet unfortenatly.

 

Looked for the parts on the BOM, and not all of the parts are avaiable from one place, witch is a drawback, since I live over here in Norway, where this kind of parts is hard to find, and postal handling is slow. Therefore getting all the parts from one place, as a kit, so i know i got all the parts, and haven't overlooked some parts, would be great.  (sorry about the poor english, and some long sentences)

post #1446 of 1686
Quote:
Originally Posted by egotrip View Post

Just recently found this awesome amp, and I want to give it a try.

I am new to head-fi, and want a good starter amp. I love the idea of a DIY project. So this is right up my alley.

I have read the entire thread, but have overlooked some crucial informasion by all the reading.

Do the kit from Glass Jar Audio come with a 110vac or 220vac transformer?

I have contacted Glass Jar Audio trough their website, but haven't recieved any answer yet unfortenatly.

 

Looked for the parts on the BOM, and not all of the parts are avaiable from one place, witch is a drawback, since I live over here in Norway, where this kind of parts is hard to find, and postal handling is slow. Therefore getting all the parts from one place, as a kit, so i know i got all the parts, and haven't overlooked some parts, would be great.  (sorry about the poor english, and some long sentences)


You should be able to get the entire kit from Glass Jar Audio - aka Jeff Rossel - with everything you need to build the whole kit.  He will give you an excel order form will all of the kitted parts on it.  If you decide like I did to build your own enclosure or would like better caps or whatever then you can elect to leave some parts out or buy extras of parts as well.  I bought the kit from Glass Jar but due to my design I ended up having to get a few more parts to make it all work the way I wanted to.  Be patient and I'm sure Jeff will get back with you.  If not, e-mail him again.  Best of luck!

post #1447 of 1686
Quote:
Originally Posted by capernicus View Post




You should be able to get the entire kit from Glass Jar Audio - aka Jeff Rossel - with everything you need to build the whole kit.  He will give you an excel order form will all of the kitted parts on it.  If you decide like I did to build your own enclosure or would like better caps or whatever then you can elect to leave some parts out or buy extras of parts as well.  I bought the kit from Glass Jar but due to my design I ended up having to get a few more parts to make it all work the way I wanted to.  Be patient and I'm sure Jeff will get back with you.  If not, e-mail him again.  Best of luck!



I just recieved an e-mail from jeff. just as you described, an excel orderform, neatly arranged.

I also got an answer to my question of the transformer primary voltage.

The Transformer is dual primary 
so it will work for either voltage.

My order will be placed in a near future biggrin.gif

post #1448 of 1686

So I've been using the SOHA II for a while now and I've noticed a problem creeping up. After about a year, when listening to the amp with increasing frequency I get a crackling noise in one channel (usually left channel) then the E12 kicks in. At first it seemed that it was due to me having the tube voltage set to 100v. I changed it back to 60v and it seemed that the problem went away, but now it is back. I've tested the amp and the only thing that is weird and has been weird since I built the amp is the difference between TB+R and TPR is 15V instead of 19V. TB+L and TBL measure 19V. The tail current is set correctly. I've tried a number of tubes as well. 6N2P, GE 5963, Sylvania 5963, Sylvania 5814A, CBS Hytron 5814A. I get the same problem with all.  I've already checked for shorts and cold solder joints and there's nothing obvious.

 

Anyone have any thoughts on where to start troubleshooting?

 

post #1449 of 1686

If you mean by "kicks in" that the E12 is muting, then the relay contacts are bad.

If you mean it has un-muted then the problem is likely in the input circuit.

The E12 shorts out the input when it's muting and releases the short when un-muted.

The problem is not likely to be after the tube as it would be there weather the

circuit was muted or not...

 

Good Luck!

post #1450 of 1686

What I mean by 'kicks in' is that I hear crackling and the E12 mutes. Then a few random seconds later it un-mutes, then some random time later more static/crackling and the E12 mutes again.
 

Quote:
Originally Posted by Avro_Arrow View Post

If you mean by "kicks in" that the E12 is muting, then the relay contacts are bad.

If you mean it has un-muted then the problem is likely in the input circuit.

The E12 shorts out the input when it's muting and releases the short when un-muted.

The problem is not likely to be after the tube as it would be there weather the

circuit was muted or not...

 

Good Luck!

post #1451 of 1686

In that case I would be looking at the output stage and servo.

The DC offset protection of the E12 is probably kicking in.

Can you monitor the output with voltmeter and see if you are

getting excess offset?

post #1452 of 1686

I will once I have the chance. I'm guessing at this point that Q1, Q2 for the right channel will need to be replaced. This is based on prior conversations in this thread. My first step should be to resolve the voltage difference issue that I described earlier. Then go from there I think. What are you thoughts?
 

Quote:
Originally Posted by Avro_Arrow View Post

In that case I would be looking at the output stage and servo.

The DC offset protection of the E12 is probably kicking in.

Can you monitor the output with voltmeter and see if you are

getting excess offset?

post #1453 of 1686

I have finally ordered myself a Soha II kit.

Just waiting for Jeff to process the orderform, pack and ship it.

To bad International shipping is slow....

post #1454 of 1686

Anyone knows the diam.. on the shaft of the alps pot (6,3mm)?

and where to find powerswitch to use, I am looking for a on/off rotary switch w/same shaft diam.

This for use with idetical knobs.

post #1455 of 1686
Quote:
Originally Posted by egotrip View Post

Anyone knows the diam.. on the shaft of the alps pot (6,3mm)?

and where to find powerswitch to use, I am looking for a on/off rotary switch w/same shaft diam.

This for use with idetical knobs.



6mm

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