how to set bias and dc offset?
hi Mr. Mile
i've build your AX17S, it work nice...sound is comparable with my GC even i only use standar componet. This is my first Solide State i've ever build.
I use +-44 volt DC.
there are few question i want to ask:
1. how to set bias? i've measured 0R33 and can't get fix value, is this normal?
2. my dc offset is about 34mv is this normal too?
attach is pic of AX17S build
thanks and regards
naf
hi Mr. Mile
i've build your AX17S, it work nice...sound is comparable with my GC even i only use standar componet. This is my first Solide State i've ever build.
I use +-44 volt DC.
there are few question i want to ask:
1. how to set bias? i've measured 0R33 and can't get fix value, is this normal?
2. my dc offset is about 34mv is this normal too?
attach is pic of AX17S build
thanks and regards
naf
Attachments
Dear Mr. Mile,
i measured voltage across 0,33R without load i get 0mV, and with load i get about 3-15mv up and down.
"...and for TEF it's will be about 3,2V for any bias current"... how to measured this?
thanks and regards
naf
You must connect input gnd to psu gnd for test, many people made same mistake.
Can you post pictures?
Regards
Last edited:
AX-14
Haha thanks Apex, now work
i must remember for the future... Bias is 10mV . DC output is ~ 1mV. I have a little weak trafo, only 2x45VDC and drops to 2x40VDC under load. Next be made HV350, and I think it enough for me AX14 will be to the subwoofer, work with HL2. I'm interested in class "H" I've never heard of such an amplifier.
Anyway, thanks for the diagrams... And i'm thinks AX14 is good for home audio for normal people hehe.
Haha thanks Apex, now work
i must remember for the future... Bias is 10mV . DC output is ~ 1mV. I have a little weak trafo, only 2x45VDC and drops to 2x40VDC under load. Next be made HV350, and I think it enough for me AX14 will be to the subwoofer, work with HL2. I'm interested in class "H" I've never heard of such an amplifier.Anyway, thanks for the diagrams... And i'm thinks AX14 is good for home audio for normal people hehe.
Attachments
I was one of them,with NX14. Same mistake with both channel. DC offset was 30VDC,gone with connecting input ground with PSU ground,just as APEX said.
I missed that in wireing amp...
Haha thanks Apex, now work
Anyway, thanks for the diagrams... And i'm thinks AX14 is good for home audio for normal people hehe.
Nice work, but put outputs and drivers on pcb without wires.
Regards
Yes of course
Wires is only for test, i have heat from other amp whit pair 2SC5200/ 2SA1943 and I want to see who plays better. I think it's your have a more bass , good dynamic, maybe louder sound later I'll add him another pair "AX20", pity that there is a silent shutdown integrated on PCB, on some transistors...P.s. You have maybe PCB Layout for AX20 ??
Mr. Mile,
thanks for your suggestion, (i use 1k +330R in series) now i can turn my 1k Pot to adjust bias on 0.33R... and it's very difficult to set even i use multiturn pot, when i close to 15mV value suddenly it jump to 200mv. Any suggestion?
and for DC offset of my AX17S, i've done all your suggestions and my DC offset down to 15mV (without dc servo). What your next suggestion to correct my dc servo circuit?
thanks and regards
naf
thanks for your suggestion, (i use 1k +330R in series) now i can turn my 1k Pot to adjust bias on 0.33R... and it's very difficult to set even i use multiturn pot, when i close to 15mV value suddenly it jump to 200mv. Any suggestion?
and for DC offset of my AX17S, i've done all your suggestions and my DC offset down to 15mV (without dc servo). What your next suggestion to correct my dc servo circuit?
thanks and regards
naf
thanks for your suggestion Mr. Mile. I'll try it and post the result ASAP
Use regulated PSU5 ans set +/-55V DC output voltage, without regulated psu this transformer can't be use for AX14, ac voltage is to high.
Regards
