100W Ultimate Fidelity Amplifier

vargasmongo3435 · 2014-12-04 1:27 pm

alex mm said:
...... Another PCB dual in line ,
Regards ,Alex

beautiful layout

Regards
Juan

still4given · 2014-12-04 2:02 pm

apexaudio said:
What is frequency and level of oscillation?

Just feeding a 1k sine wave. I see oscillation on the top portion of the wave. It's there on the top portion of a square wave too. Only happens with a load attached.

apexaudio · 2014-12-04 2:10 pm

still4given said:
Just feeding a 1k sine wave. I see oscillation on the top portion of the wave. It's there on the fop portion of a square wave too. Only happens with a load attached.

It's happens with 10R/100nF zobel and 2,2uH inductor?

still4given · 2014-12-04 2:14 pm

I haven't tried it with the zobel and inductor yet. This is just with the scope attached to the output. I'll add those and retest. If those are required, why aren't they shown on the schematic?

apexaudio · 2014-12-04 3:02 pm

still4given said:
I haven't tried it with the zobel and inductor yet. This is just with the scope attached to the output. I'll add those and retest. If those are required, why aren't they shown on the schematic?

I use speaker terminal with all amps.

still4given · 2014-12-04 3:16 pm

Do you see oscillation without it?

apexaudio · 2014-12-04 3:31 pm

still4given said:
Do you see oscillation without it?

You must ask Olaf.

olafk · 2014-12-04 5:27 pm

apexaudio said:
You must ask Olaf.

I have not seen it. On scope I had a clear sine wave (see picture 20kHz).
Without Zobel and in in temporary wiring. The only difference is using other drivers. I have the 4793/1837 replaced with 2SC2238 and 2SA968 and i used NE5532 because I had this time no others.
Currently I have no other idea.

regards Olaf

olafk · 2014-12-04 5:31 pm

Layout A9

Some users ask via PM for lay-file of A9. So here it is. Makes no sense to send mails.
It`s DIY

regards Olaf

thimios · 2014-12-04 5:59 pm

olafk said:
Some users ask via PM for lay-file of A9. So here it is. Makes no sense to send mails.
It`s DIY

regards Olaf

Makes no sense to send mails.
It`s DIY :wave2:

Vostro · 2014-12-04 6:28 pm

I've never ran any of my amplifiers without a RC zobel.

sonal kunal · 2014-12-04 6:38 pm

Miles can you verify this A9 pcb layout.

Regards.

apexaudio · 2014-12-04 7:12 pm

still4given said:
I built the A17 based on the layout in post 3551. The only changes I made was to use 500p in place of 470p because I didn't have any on hand. I used NJW0281/0302 for the outputs. I get oscillation when a load is connected. Suggestions welcome.

Thanks, Terry

Add this compensations.

apexaudio · 2014-12-04 7:20 pm

sonal kunal said:
Miles can you verify this A9 pcb layout.

Regards.

Nice pcb,
Regards

still4given · 2014-12-04 7:25 pm

olafk said:
I have not seen it. On scope I had a clear sine wave (see picture 20kHz).
Without Zobel and in in temporary wiring. The only difference is using other drivers. I have the 4793/1837 replaced with 2SC2238 and 2SA968 and i used NE5532 because I had this time no others.
Currently I have no other idea.

regards Olaf

Hi Olaf,

When testing without the zobel, did you have a dummy load attached? Mine looks fine without a load attached.

I hooked it up through a Zoble this morning and that did the trick. I learned something new today. I'll do some listening to it a little later. I have a TL072 in there right now. I have ordered some more HiFi op-amps to try out. Before a month ago I had never used an op-amp for anything but a servo. Now I have 4 amps built that use them in the signal path. Ain't DIY grand!

Blessings, Terry

apexaudio · 2014-12-04 7:37 pm

still4given said:
Hi Olaf,

When testing without the zobel, did you have a dummy load attached? Mine looks fine without a load attached.

I hooked it up through a Zoble this morning and that did the trick. I learned something new today. I'll do some listening to it a little later. I have a TL072 in there right now. I have ordered some more HiFi op-amps to try out. Before a month ago I had never used an op-amp for anything but a servo. Now I have 4 amps built that use them in the signal path. Ain't DIY grand!

Blessings, Terry

Arcam use TL072 in many CFA amps, and Zeck use NE5534 in PT series CFA PA amps with SR 100V/uS. Sound good?
Next step class D

Regards

apexaudio · 2014-12-04 8:44 pm

A23 15kHz 8r 2V/div

olafk · 2014-12-04 9:42 pm

still4given said:
Hi Olaf,

When testing without the zobel, did you have a dummy load attached? Mine looks fine without a load attached.

I hooked it up through a Zoble this morning and that did the trick. I learned something new today. I'll do some listening to it a little later. I have a TL072 in there right now. I have ordered some more HiFi op-amps to try out. Before a month ago I had never used an op-amp for anything but a servo. Now I have 4 amps built that use them in the signal path. Ain't DIY grand!

Blessings, Terry

Yes, I used a dummy load. I have to big 12R 50W so parallel 6R and also parallel with 470n.

still4given · 2014-12-04 10:03 pm

Thanks,

It is playing fine now with the zobel attached. I listened to it for a while. Sounds very good as expected. The gain is a little lower than some of the other Apex amps. When I find my camera I will show some square and sine waves.

Blessings. Terry

alex mm · 2014-12-04 10:11 pm

PCB REV 1.1

Thanks , and pcb rev 1.1 with less jumpers ,last schematic used here ....

I will build soon as possible .
Regards,Alex

100W Ultimate Fidelity Amplifier

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