RMI-FC100, a single stage audio power amplifier

[DRZ1]

Originally posted by roender


Denis,

I think you have some ground wiring problem, or more than 92bB SPL speakers.
Where did you put the speaker return wire? Into the star ground, in the middle of the board?

Yes it's connected to the star ground. I suspect the small transformers i have used for the drive supply, but i'm not shure.

I have made some tests (distance it ) and i have found the front end pair very sensitive to electro-magnetic fields.

Maybe my ground plane PCB (not grounded in fact ) ????

If you have some other idea.

Thanks

[MJL21193]

Originally posted by MJL21193
Here's the first working model of my version with bjt input:

No comments on my escapades? Oh well.

I put it on a heatsink and did a full power test - looks very good. I have configured it to run on +/-72V rails, but input sensitivity limited to 150 watts output. This ensures plenty of headroom to avoid clipping.I worked out some of the bugs and finalized my layout:



All of the outputs plus the CFP drivers are mounted under the board in contact with the heatsink.
Thanks roender for the great design.

[robson fulco]

HELLO GOOD AFTERNOON!!
HOW FASO TO ACHIEVING A CARD THAT YOUR AMP. Was reading out about ELE And I love OK ....

[housing]

Hi Mihai,

How did you match the transistors? Thanks!

[roender]

Originally posted by housing
Hi Mihai,

How did you match the transistors? Thanks!

Which transistors?

[housing]

Q19-Q20
Q1-Q3

Thanks.

[roender]

Use a DMM to measure hfe.

[pooge]

Any opinion on which of these transformers would be best for the output stage for a single channel? The Antek is a lot cheaper and heavier, but I read an opinion somewhere, without explanation, that the Avel was better quality. Is anyone familiar which any quality difference between these lines of transformers?


Avel Transformer

Antek Transformer

Has anyone found a USA supplier for a standard off-the-shelf transformer for the input stage?

[jcarr]

Mihai, just wanted to offer my congratulations on a clean, capable design that shows that you have put a lot of thought and time into it. It is a pleasure to look over your work. Nice!

In fact, it looks like something that I would design (^o^).

Happy holidays! jonathan carr

[roender]

Originally posted by jcarr
Mihai, just wanted to offer my congratulations on a clean, capable design that shows that you have put a lot of thought and time into it. It is a pleasure to look over your work. Nice!

In fact, it looks like something that I would design (^o^).

Happy holidays! jonathan carr

Mr. Jonathan Carr,

Thank you very much for your kind words.
I must confess that I am a big fan of yours and I'm glad that we have you back on diyaudio ... I hope.
This design is very much yours. I was guided by many posts you had writhed on the net.
I would like to ask you a question, if I may?
I've been thinking to version two of RMI-FC100 for a while. I want to use Li Ion rechargeable battery as front end power supply and I don't know if i could replace LTP CCS with a simple resistor and also all folded cascode CCSs with JFETs configurated as CCS at zero TC, in order to allow an exceptional HF behavior.
I would like to make this design as simple as possible from singal path point of view.
What do you think about?

Best regards and
Happy Holidays,

Mihai Rauta