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-   -   Suggestions for mono block amplifier? (http://www.diyaudio.com/forums/solid-state/214363-suggestions-mono-block-amplifier.html)

Duco 12th June 2012 06:02 PM

Suggestions for mono block amplifier?
 
Dear All,

I just finished my first amplifier ever. And it sounds wonderful to my opinion:D It's based on the L12-2 amplifier board often offered on ebay.

But I still got some transformers and capacitors left:
2* 300VA 2x22V transformers
4* Mallory 17000MFD @ 40V
4* (oversized) Sprague 50000MFD @40V
8* Philips 15000MFD @ 40V

I was thinking to build a set of mono block amplifiers, not too fancy but nice enough for my monitor audio RX2 speakers. Can some one help me point out some amplifier kits? I am still a rookie so i don't think I can handle a build completely from scratch.

Hope you can help me:)

-Duco

jacco vermeulen 12th June 2012 06:19 PM

22Vac/300VA isn't tempting for Class AB.
(is for a balanced design, but that's not rookie territory)

Transformers and caps say Class A, so says the RX2.

Easy to build with off the shelf PCBs : Cascoded F5, CViller's boards in the store.

Duco 12th June 2012 06:40 PM

Thanks for the quick reply!

I will have a look at the Cascoded F5.

In the meantime, how about these:
-Duco

Duco 12th June 2012 08:20 PM

Just stumbled upon these:

FL A1000 30W+30W Class A MJ15011 15012 Amplifier boar | eBay
Hiraga super 30W class A amplifier kit ! | eBay

I like the first one, for some reason I've got a some fetish for TO-3 transistors..
But eventually it's all about the sonic properties of the amplifier...

In my eyes all amplifier a somewhat qualified, but I'm not sure about the working voltages. With a rectifier and a 2* 17000MFD Mallory capacitor bank I get +/- 32V. So what is a wise decision?

audiostar 12th June 2012 11:20 PM

How about SKA GB150 or GB300 ?

jacco vermeulen 12th June 2012 11:37 PM

Second that, Mr Ball's is not half bad for it's simplicity.

(me did a GB50D in full Class A with 25Vac Amplimos)

Bigun 13th June 2012 12:46 AM

my vote goes for a JLH 1969 Class A amplifier. Last time I looked there were pcb's and kits available on ebay. Here's an example from a seller with 100% feedback rating:
http://www.ebay.ca/itm/2pcs-High-qua...ht_3494wt_1413


The circuit is simple and elegant - learning about how it works is worthwhile.

The Class-A Amplifier Site

It's capacitor coupled output so built-in speaker protection. If you use 2N3055 power output transistors they should be easy to find at a reasonable price and you shouldn't have to worry about amplifier stability/frequency compensation since they are relatively 'slow'. The amp has an excellent reputation for sound quality.

The Hiraga amps are also excellent, but I believe they are more prone to power supply hum at the output.

With any Class A amplifier you'll need to get some heatsinks. They will need to be large. But they don't need to be fancy so look around for eBay options.

and I'm willing to follow my own advice - I'm currently building a dual-mono JLH 1969 myself.

It's one of the most popular amps of all time and there's a long standing thread about it here: http://www.diyaudio.com/forums/solid...amplifier.html

Duco 13th June 2012 10:56 AM

I have looked at all results so far and narrowed my options:

This ones should work perfectly on +/- 32V without adjustments right?
MX50X2 Class AB Power Amplifier Board AMP Kit 2-Channel | eBay

Hiraga super 30W class A amplifier kit ! | eBay

FL A1000 30W+30W Class A MJ15011 15012 Amplifier boar | eBay

And the SKA GB150

I don't have a ridiculously high budget, so i'm wondering what is wisdom..

wahab 13th June 2012 11:53 AM

Quote:

Originally Posted by Duco (Post 3057949)
I have looked at all results so far and narrowed my options:

This ones should work perfectly on +/- 32V without adjustments right?
MX50X2 Class AB Power Amplifier Board AMP Kit 2-Channel | eBay

This one should have the best perfs of the three mentionned
in the post above.
Besides , the guy give the schematic , wich show a classic topology
that perform well, yet it can be improved with very few typical mods
that you can fish in this forum not counting that depending of your
heatspreaders it can be biaised in class A.

Duco 13th June 2012 12:53 PM

Quote:

Originally Posted by wahab (Post 3058001)
This one should have the best perfs of the three mentionned
in the post above.
Besides , the guy give the schematic , wich show a classic topology
that perform well, yet it can be improved with very few typical mods
that you can fish in this forum not counting that depending of your
heatspreaders it can be biaised in class A.

Allright. How "in short" can I modify it to run in class A? Is it better than the SKA GB150? I read good things about them..

-Duco


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