[runeight]

And, of course, are the pinouts correct?

 

[sachu]

Right..except don't think i have any 3.3k resistors lying around.
 
Okay..switched to the MJE devicces..I read 0.5V between the test pointss and Out.
 
However, positive rail is getting slammed is being pulled down to 1V. Positive regulator gets real hot.
Negative rail is steady on both boards.
 
Output DC Offset is reading ~ -27V wrt SG.
 
Its on both boards.
 
**facepalm**  How could i forget..indeed the pinouts are reversed on the toshibas..
Will switch the back..but will need to figure out why the positive rail is getting hit so bad. .

 

[sachu]

okay..switched the toshibas around..the half way mark on the trimpots nearly is perfect to bias them up. Glad i installed the transistor sockets..so much easier to these things.
 
Everything is kosher now.
 
However strange thing about the MJE devices..once i grounded the input the DC offset on the out put went away. With the toshibas even with the inputs ungrounded DC offset is at 0V.

 

[sachu]

One more thing..mounting the toshibas bring in another problem..the heatsinks are no longer on board and can't be socketed into the board. 

 

[runeight]

If the Toshibas have exacty the opposite pinouts from the MJEs they should work in the mosfet positions. If so, then all you might need to do is spread the pins apart a bit.

 

[sachu]

^^..yup
 
that should work. Will need to move the sockets to the mosfet pin positions.

 

[runeight]

In the meantime, can you tell us if it makes any noise?

 

[cobaltmute]

I just fully powered up my first board.  BJT (mounted on the MOSFET pads).  Power up was smooth.  Initial bias was .9V.  Was able to trim it out to 1V with a number of turns of the trimpot.  My first test of offset showed 0.01mV.
 
Other board will be powered up on Wednesday and hopefully I'll get sound after I fix the e12 I smoked during setup.
 
I should say that with 5600uF on each rail on the PS, the time to discharge is surprisingly long.  The functioning e12 doesn't release immediately when the power goes done so I'm going to have to test to see what power off behavior is.

 

[sachu]

nearly done with the wiring. Just power supply wiring and some clean up to go and the amp will be cased up. Will get to it tomorrow.
 
Sachu

 

[Cloud]

can we use 2SC2238/2SA968?
 
i quite like the sound when used in my jisbos

 

[sachu]

Yes..those are the ones I like too and apparentlly so does cobalmute. 
Both our builds use these toshibas.

 

[Cloud]

thanks sachu. may I know which transistor socket are you using?
 
and where did you source your toshiba from? are those from ebay trustable?

 

[jdkJake]

I should say that with 5600uF on each rail on the PS, the time to discharge is surprisingly long.  The functioning e12 doesn't release immediately when the power goes done so I'm going to have to test to see what power off behavior is.

I am sure you already know this, but, the AMB website has a suggested wiring scheme to immediately release the relay by putting one of the DC supply lines through a pole of your power on switch. I did not use this technique, but, it would eliminate thump, which is slightly present upon amp power down.

 

[cobaltmute]

Yes..those are the ones I like too and apparentlly so does cobalmute. 




Both our builds use these toshibas.

I was going to use those Toshiba's but I'm using a set of Rohm's instead

 

[cobaltmute]

I am sure you already know this, but, the AMB website has a suggested wiring scheme to immediately release the relay by putting one of the DC supply lines through a pole of your power on switch. I did not use this technique, but, it would eliminate thump, which is slightly present upon amp power down.

Yeah it was pretty quick to figure out that is what I needed to do. Only thing is to figure out where to put another relay as I'm using a e24 to switch power for my amp