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Please comment on my amplifier

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Great amp. Congratulations!

cannot open the file

has the link expired, i cannot open it.


Link works,is still the same:

Amp souds great,it have great bass response at low wolume levels.
On this pictures you cant see,but now it have ALPS pot.Pot is so called blue line and is quite expensive.Amp have VU meter instead of peek indikator(that red diode in the middle)

My Leach amp is now finished,so i take a few shots to share it with all you,who helped me and those who read this forum.

Amp have classic PCB design and i used only Motorola devices (ON),capacitors are not mica;in my country i cant find them so i use quality multylayer or ceramic caps.Amp casing was not planed i just go along and add things,as you see casing is built by Prof. Leach recomendation.(added bottom plate,25mm tick for robust look).Inbus screws adds more DIY look.Casing is made by soldering copper with 100W soldering iron.Classic design,on next project-class A more exotic housing design.
As i type this words,amp is richer by ALPS blue line pot and nice VU-meter(not yet built on these photos).This upgrade is probaly final.
Specs:-weight:15Kg total
-500VA,2x42V toroid
-6x10000uF caps total
-gold plated chinch inputs-must have these
-all metal parts are groundet to central ground point
Speakers are cheap type,made by me(german people probaly know Westra drivers)but take almost anything,like 150W amp and 100W speakers work just fine.Sure you must have good crossover.

A few words for each photo:

You see my DIY interconnect cables,on top right my new Marantz CD player,In the amp you see my transformer shield(probaly dont need one,but sure looks fine Above shielding is clearly seen CGP(central ground point)
Amp,speakers-DIY,fishing gear and what is this black thing between speakers?
Is bad photo,but who gets even close i buy him Heineken beer
Amp insides while measuring bias current.Heat sinks i got for free predrilled,once used for some kind industrial transistors.All amps components is screwed to wood(painted black),to give extra safety and for easy mounting.Left knob was peek indikator,removed instead i built VU-meter.
Not wery good picture,amp was polished and flash did the rest.Dumb automatic,light was just right but stupid flash turned on.Whatever...

And at the end the most important thing(this is primary cause for writing this post)-Credits
Big thanks goes to:
Klas Mälman-his copper housing is just wonderful,and he help me a lot with ansvers.
Prof. Marshall Leach-solved power supply problems.
Vili Jan-my local PCB supplier.
Swede...and all i forgot.

All you who cant see pictures,try these links:

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Feel free to post your comments,good or bad dont matter.

My next project?Maybe class A,who knows...


Looks Pretty, but seems there`s too much unused place! Ventilation?

What u think on that chineese tester shown on the 3-d picture, as practice shows they`re wrong using high voltage\current-mode!
And of course VT-check!

shad said:
capacitors are not mica;in my country i cant find them so i use quality multylayer or ceramic caps.

Hey Shad- there are few companies in Ljubljana that have Mica capacitors on stock (at least they did a few years back).
Terna d.o.o. is one of them if I remember correctly, IR elekronika is the other I think.
There is also Conrad store in Maribor.
Oh- and as I remember Iskra used to make some pretty good caps- what happened to those?

Ceramics sucks big time when used in audio!

lightsider thanks for very useful info,and you probaly not from Mars :) maybe Slovenia?

Iskra have good capacitors,but they are very cheap and unknow quality at least for me.Maybe you have better info on them.

Ventilation is not very good,cause i forgot to isolate heatsinks from chassis.Amp get quite hot,but those heavy heatsinks (originaly used for industrial purpose) works well.

What u think on that chineese tester shown on the 3-d picture, as practice shows they`re wrong using high voltage\current-mode!
And of course VT-check!

This part i dont is a signature?


No I am not from Slovenia but from a much more wild country that borders Slovenia... :lol:

There was a magazine "Svet elektronike" that used to have usefull advertisement page in which you could find all the electronic shop adresses and phone numbers. On a few occasions I called to Ljubljana and went there for some parts that could not be obtained on Mars. :wink:

For instance-- Terna d.o.o. is a representative of Fischer-- and they are makers of heatsinks--- so for my amplifier (Heavily biased class A 2x50W) I bought the bigest heatsinks I could afford. They costed me around 35EU each and they were really effective fuckers! So- regarding that overheating you're experiencing-- go to Terna d.o.o. (or call them) and ask for Fischer catalogue- and then look for the most thermaly efective heatsink you can find (of course look for the best performance/price ratio). Fischer also have nice transistor isolators made from special materials that are almost 50% less thermaly resistive than the ordinary ones. Use those! They cost something about 1EU each but they're well worth the price paid!

As for Iskra's capacitors-- I remember that we tested some of them a few years back and they were suprisingly good considering the price. :eek: Much better than the ceramics in any case... But if you don't trust Iskra--- you can buy MKPs and MKTs made by Wima in those shops in Ljubljana I mentioned earlier.

BTW- those DMMs really sucks big time in extreme regions of measurements range! :evil:

Can you get me more detail look into your amp?
Or even your home page...
I'm asking this,cause my next project just might be biamped system with class A for high+mid.


Umm- that could be a problem since I don't have a personal webpage :oops: and the project was made by me a few years ago without use of any software so I don't have any files to share at the moment. I could at best scan the schematics (when I find it somewhere in the mess that rules in my apartment and that is when I have some spare time). But I should warn you- that amp is sounding very good but it is heavily biased and dissipate some serious heat... You can easily heat a room during winter... :eek: :eek: :eek:

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