RAS-300 Mosfet Amp.

[Eugenio70]

Hi Justin, thanks for the link. Well I just recently finished an Albert Kreuzer JFET bass pre-amp, the stand-alone one. It's working great and I'm looking to add a power section and turn it into an amp head. I'm also considering the BPA200 using LM3886 chips, couse it looks simple, but have not decided.

Thanks for the replies!

Eugenio

[Andy L. Francis]

Originally posted by terranigma



Hi Andy, your allegations seem very serious. Can you discuss this with Ras via email?

That would be very instructive for us if you discuss here.

Sorry folks, I hope I didn't offended anyone.
Any engineer who is adept in amplifier design should agree that this amplifier has some serious design fault. I doubt it works fine.
Again, I'd never suggest anyone to build these amplifiers.
I'm not against Ras, I don't know him. I wouldn't offend him.
I claiming that his designs aren't good, and I can state why I think that.

[gnalbant]

Dear Andy,

I am not an expert on electronics, however, as far as I know from our experience with my friends, Nico's mosfet amps sound really very good, when we consider reproducing the original instrument sound.

I am not defending Nico, may be I should, I don't know

His designs may be based on Hitachi notes which sounds quite logical to me, but the result is quite good.

We built two prototypes, and impressed from how they sound.

And he is a perfect supporter, all about his designs.

Maybe those points are all emotional, not about the technical design, but as a DIY member, I am quite happy about the results.

However, I'd also like to learn your points about the design issues, which is an opportunity see the thing from another point of view.

[peranders]

It can sound better than it ought to but I wonder how it would sound with more idle current in the VAS stage and also when it's really hot.

[engel dela pena]

eugenio
good day
we have a reverse problem i already have amp module looking for guitar amp,while you have pre amp looking for amp project,i suggest you build quasi's nmos 200 see his page

[Eugenio70]

Originally posted by engel dela pena
eugenio
good day
we have a reverse problem i already have amp module looking for guitar amp,while you have pre amp looking for amp project,i suggest you build quasi's nmos 200 see his page

Hi Engel, I had missed this amp, looks very good!! Exactly what I was looking for, and looks easy enough. I am still pending on loading some pictures of the pre-amp, will do it soon.

Thanks!

[Bruce@bluff]

you can build it but just know it will NEVER deliver the advertised
power it will give about 130 watts into 8 ohms and about 240
into 4. There is a thermal stability issue with those diodes
which will cause the quiecent current to vary consideribly they need to be replaced with a 470 ohm preset so the quiecent can
be set accurately. The distortion figures are also highly
exaggerated above 5khz the distortion in this circuit rises sharpley reaching almost 2% at 20khz therefore definatley NOT
hi fi good for guitar or subwoofer. Why don't you just build Rod
Elliot's guitar amp it includes a pre -amp and realistic power output figures and i.m.h.o. is easier to build with easily obtained bipolar output stage.

[Eugenio70]

Originally posted by Bruce@bluff
you can build it but just know it will NEVER deliver the advertised
power

Hi Bruce. Are you refering to the RAS300 or the NMOS200 amp?

Thanks!

[Andy L. Francis]

Originally posted by Eugenio70



Hi Bruce. Are you refering to the RAS300 or the NMOS200 amp?

Thanks!

I think he misunderstood something and referred to RAS300.

I'm sure Nmos200 works fine.

[Bruce@bluff]

Yes i was refering to the ras300. I havent seen the nmos200.