Amp biasing again...

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klaus@odyssey

Re: Amp biasing again...
« Reply #100 on: 3 Nov 2020, 06:44 am »
1.  124 V...this is exactly why I am so hot on the issue of biasing.....124 to, let's say a standard 120 V setting is HUGE !!!!   Huge in any amplifier design btw. 

2. Synergy with the Maggies is one of the 2 best I've ever found...just awesome...

3.  22 +  mV  would be a bit too much for my own personal taste,  but because there are dozens and dozens of different tweaks and upgrades out there in my nearly 7000 amps,  they also behave different in different systems,  et al.....

4.  Honestly,  don't listen to others about what's best on the test points...use your own ears,  and float your own boat......


VOTE !!!  AND STAY SAFE !!!!

arfan

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Re: Amp biasing again...
« Reply #101 on: 3 Nov 2020, 10:07 pm »
Thanks again Klaus. Good to know and appreciate your opinion on the  maggies and Odyssey amps, it helps to hear an expert on the subject and reinforces what I'm hearing.
When you Say too much on the bias setting, are you referring to a warmer setting? I have an Audible Illusions M3B Tube pre newest update and the match gives goose bumps to these old ears.


klaus@odyssey

Re: Amp biasing again...
« Reply #102 on: 4 Nov 2020, 08:00 am »
In general and for most amps:

-  higher bias = rounder, fuller, more bass

- lower bias the opposite = faster, leaner, more detail oriented as a result


that's why I optimize the bias according to the tonal balance of the speakers,  within reason......but yes, if you want to get the absolute maximum of what's possible in the amp,  then we'll have to bias it just right....if that falls off,  then so does the sound.  That's also why it's a good idea to have me to adjust for a new owner if bought used,  and that's why I'm banging my head against the wall  when there's an idiot complaining about a used amp's performance when the bias is obviously off.

Again,  I can just go ahead and bias the amp 2-4 mV less than optimum,  but that's not really in my blood.....if you can go to 11,  then go to fukking 11 !!!!


brad1138

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Re: Amp biasing again...
« Reply #103 on: 2 Jul 2021, 03:06 am »
I do want to check/adjust the bias in my Stereo Kismet in Khartago case. This appears to be the place to request the instructions. My Moabs love a warm amp, and as cool (temp wise) as my Kismet runs, I think it might be worth the check.

Klaus you already have my email, PM me if needed. (no rush)

Thank you!

PS, always go to 11! ;)   https://www.youtube.com/watch?v=KOO5S4vxi0o

brad1138

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Re: Amp biasing again...
« Reply #104 on: 2 Jul 2021, 05:39 pm »
that last little bit was what i was missing.

since it looks like many have asked, and i finally have complete instructions, i built an image to help everyone out.
by the way, to adjust the offset it is much easier if you have a ground lead that you can clip into the board. you might want to pick one up before you start.




Again, thank you for that.

On the stereo version amps, wouldn't it be fine to just read bias from the speaker terminals? You wouldn't need a clip.


brad1138

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Re: Amp biasing again...
« Reply #105 on: 3 Jul 2021, 12:12 am »
My bad, I read that wrong, You can read offset from spk terminals, not the bias. (Not the positive anyway)

brad1138

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Re: Amp biasing again...
« Reply #106 on: 5 Jul 2021, 06:18 pm »
OK, I am fairly sure I have my head around it. It would have been easier if not for typos and contradictions in the posted instructions. Also the difference between mono and stereo complicate it a bit.

Johns nice picture is great, but it says TP6/7 when I am pretty sure he meant TP5/6.

The 1st part for the written instructions say to use TP1/2 & TP5/6, with no mention of TP3/4 or TP7/8. Then towards the bottom, it says use TP3/4 and TP7/8 and ignore TP1/2 & TP5/6....

I really don't know for sure which is correct, and why not use all 4 per side?

I think Johns picture instructions are the most easy to follow, short the typo.

If anyone could offer clarification on which TPs to use, that would be great.

It seems clear that you can connect the negative DVM lead to the negative speaker terminal, and leave it there for all testing (per side). The positive would go to the corresponding positive speaker terminal for offset and the "TPs" for Bias adjustment.

Thanks for the help, I am REALLY not trying to be obnoxious.  :)


klaus@odyssey

Re: Amp biasing again...
« Reply #107 on: 5 Jul 2021, 07:17 pm »
OK,  Brad et al,

You only use 1 test point per side....!!!!!!!!!!!!!
Either TP  3 or 4 on one side,  and either 7 or 8 on the other....you only use the one with the highest value per side of the board and completely ignore the other 3 of that side !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

On another note,   Brad,  your Candela is ready to go !!!!

brad1138

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Re: Amp biasing again...
« Reply #108 on: 6 Jul 2021, 10:08 pm »
OK,  Brad et al,

You only use 1 test point per side....!!!!!!!!!!!!!
Either TP  3 or 4 on one side,  and either 7 or 8 on the other....you only use the one with the highest value per side of the board and completely ignore the other 3 of that side !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

On another note,   Brad,  your Candela is ready to go !!!!

OK, thank you again. I understood you only use one, but you check 2 at first to verify which one is higher.

I spoke with Klaus on the phone just a few hours ago, he clarified to use the red speaker terminal, which is ground, for bias adjusting.  I always have it in my head that black is ground, so that confused me a bit.

brad1138

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Re: Amp biasing again...
« Reply #109 on: 6 Jul 2021, 11:51 pm »
I just spoke to Klaus again for reverification. Red is not ground (I called him after I verified that with an ohm meter), but it is what is supposed to be used along with TPx for bias adjusting.

Every set of instructions posted in this thread says to use ground and TPx for bias THAT IS INCORRECT. He asked me to post that here, and he may chime in about it also.

brad1138

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Re: Amp biasing again...
« Reply #110 on: 10 Jul 2021, 06:02 pm »
OK, I bought a 2nd Multimeter to compare and make sure they were both accurate.

Klaus recommends bias between 18 and 24 mV, my Kismet was 12 mV on both sides  :o . The offset was about 3 mV on left chan and 13 mV on right. Both within an acceptable margin. I am going to aim for 21 mV and 0 mV and see how it it sounds, then go from there.


klaus@odyssey

Re: Amp biasing again...
« Reply #111 on: 12 Jul 2021, 08:54 pm »
Anybody trying to do this on your own,  CALL ME  FIRST !!!!!!!