Mistakes you made with your β22 or σ22 - Page 5

I don't think that adding another 1R realistically has any downside, might as well add it in case you get your hands on some 8-ohm vintage headphones. :p

Good read guys.

I'm no where near building a b22, but let me see if I can contribute at all.

General mistake:

When using a DMM, make sure that you don't leave your leads plugged into the high current outlet if you had been using that for any reason. It practically shorts out anything no matter what mode you have it set at.

I blew a mosfet on my SSMH that way

This is one wonderful thread. I've been searching and collecting pieces of faults and advices here and there for months to prepare for my build at the end of this year. Keep building it up guys, hopefully I will have music coming out from my B22 right in the 1st run :D

Found this post this afternoon, not mine but still a pretty good experience for people here.
 

Quote:

Originally Posted by ting.mike 

The problem I find with the Beta22, as amazing as it is, is that it doesn't seem to like single ended headphone very much. The issue with TRS plug makes it necessary to install higher R34 and R35 to avoid blowing up the mosfet. This has happened twice on my 4 channel B22.
 

And also Lil Knight just blew the hell out of his B22 while testing, I will tell him to chime in soon :D

Quote:

Originally Posted by tranhieu 

This is one wonderful thread.  ...  And also Lil Knight just blew the hell out of his B22 while testing, I will tell him to chime in soon :D

Not to beat the dead horse of 1Ω R34/R35 & TRS plugs, but have yet to have anything blow in my 24V+/- 2ch budget b22 that has stock R34s/R35s. 

And at a meet I brought it to I caught someone pulling his 1/4" jack vvveeerrryyy slowly, like 1 full second to remove it.  Probably did same on plugging them in. Let him know to do it briskly & why.  So I'll be installing 1Ωs per amb's specifics I linked to earlier.

Agreed, great thread.

 Yes it was very kind of John W McLean to make such a great list......

I have heard that the Beta 22s have a problem bruning even when build by experienced builder so I am weighting options, I know better than to ask...

Quote:

Originally Posted by cfcubed 

Not to beat the dead horse of 1Ω R34/R35 & TRS plugs, but have yet to have anything blow in my 24V+/- 2ch budget b22 that has stock R34s/R35s. 

And at a meet I brought it to I caught someone pulling his 1/4" jack vvveeerrryyy slowly, like 1 full second to remove it.  Probably did same on plugging them in. Let him know to do it briskly & why.  So I'll be installing 1Ωs per amb's specifics I linked to earlier.

I "hot" insert and remove the TRS plug on my own 3-ch active ground β22 (with default 0.47 ohm output resistors) all the time, and it has been to numerous meets with TRS plugs inserted and pulled regularly, and not a single problem.  One only has to make sure that the amp's DC offsets are nulled well, and the volume control should be turned down to minimum before inserting/removing the plug.  If you're paranoid, increase the resistor values (this is described at the β22 website in the "Parts list" and "Initial setup" sections), or power off first before inserting/removing the plug.

My Beyer T1s caused my 3-ch gain8 Beta to oscillate at low volumes only.

Based on some advice from amb and others I ordered the parts for a zobel, but since I also wanted to reduce the gain anyway- also ordered the parts to try 5x and 2x gains.

Started with 2x gain and no zobel network, and upon testing found no (audible) oscillation issues with any of my headphones (HD650, T1, SR60, D1001, etc).  I've made no other changes and had no issues since.
 

Quote:

Originally Posted by JB197 

Thread resurection!

 

Guys, regarding your Beta 22 builds I would like to know about oscillation...

 

Who has experienced oscillation?

How did you detect it?

What caused it?

What did you do to fix it?

 

 

Thank you,

J.

Quote:

Originally Posted by amb 

 

One only has to make sure that the amp's DC offsets are nulled well

Hi amb,

I guess all solid state amps without servo (or output caps) drift a little, so how much does the Beta22 offset drift with respect to time?

If it is approximately 0mV a few minutes after turn on how much is it likely to drift over, say, an hour or so?

Thanks,

J.

Quote:

Originally Posted by JB197 

I guess all solid state amps without servo (or output caps) drift a little, so how much does the Beta22 offset drift with respect to time?

If it is approximately 0mV a few minutes after turn on how much is it likely to drift over, say, an hour or so?

Not much... I've never seen mine drift more than a few mVs, which is negligible.
 

OK, many thanks for your reply.

Quote:

Originally Posted by tranhieu 

And also Lil Knight just blew the hell out of his B22 while testing, I will tell him to chime in soon :D

I didn't know that the R34, R35 turning brown could be called 'blow the hell' ;)

This is a totally different anyway. I got the overheated R34,R35 on the ground board while doing the initial setup, not because of plugging/unplugging the TRS jack. Still trying to figure out the bug but I already have a running 2-channel.