Hiraga "Le Monstre"

Dan,

A nice job indeed... Congratulations. :up: Mine usually look like they were put together from stuff pulled out of the garbage, because... well.... :eek:

Hi Karel,

The Function of that circuit is speaker dc protection/de thump

So far i have only listened for a little while but it sounds very good :)
I am using Elsinore Mk. 3 speakers.

-Dan

OT: What circuit are you using for speaker protection?

Cheers

Nigel
 
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Joined 2005
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Hi Nigel,

Thanks :)

The circuit i am using is a old silicon chip (aus magazine) one
It is a filter circuit which passes ac but activates a relay with dc, some square wave signals also can trip it similar to clipping...

I am sure they were not the first to use it. and there is many variants of it around. The kit is now discontinued and they have replaced it with a similar version but with thermal protection and some other stuff, i have one at home but i opted for this one it seemed a shame to waste it.

PS: your stuff does not look like rubbish more like a good use of surplus electronics !

-Dan
 
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Joined 2005
Paid Member
Hi all,

Neazoi, I think there is an audible difference to the Le class A 20W
the mostre seems a little bit more natural/better also requires a little bit more gain on the input..

it is able to go very loud with my Elsinore speakers so i am very happy at the moment it is what i listen to on a day to day basis

Actually i am very happy with the results - the heatsink runs at not much over room temp, and the amp is very quiet you have to have your ear right up near the tweeter to hear any noise with it connected but not signal - and this is mostly the cd player/preamp noise

I have not taken a very good pic of the amp from the outside but here is a pic anyway ... notice when i was at work one of the 2 cats has investigated the amp.... the top needs a wipe dusty for waiting to go onto the amp
and there is a small slit you can see through which i have to re-align...
An externally hosted image should be here but it was not working when we last tested it.


-Dan

-Dan
 
I just tested the amplifier. all the I/O cables are messy but I couldn't wait to give it a go. It works, it amplifies, this means no error on the circuit, but the 1 Ohm resistors get too hot. Mine are 3.5-4W and the schematic suggests 5W.

With the configuration shown on http://www.audio-constructions.com/monstre/Hiraga-Monstre-Monster-Class-A-amplifier-schematic.png the voltage drop across the resistors is 2.7V!! I have not made any adjustments yet, I just wanted to see that it works for now. maybe that is why the resistors get too hot?

Oh something else I plugged the batteries using cables and no switch and I got a nice spark from the huge initial draw current of the caps.... You wonder if this sparc would exist inside the future added switch? No, if you add a switch there is no spark I have tested it.

Not even adjusted and the sound is very transparent and it seems the bass region goes too low. The middle and highs are just excellent I have not heard anything like this before. I wonder how they will be when adjusted.
The volume is exceptionally high I guess it is much more sensitive than I thought, perfect for a passive preamplifier, as I had to adjust the volume of the internal attenuator of the CD to the minimum and still it was very loud for my room (I have 90-102dB speakers).

An exciting moment to see everything working as expected!

I cannot wait to make the adjustments (and replace the 1 ohm resistors with bigger wattage ones?)
 
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hi all fron Burgos (spain)Neaozi tell us more about your final impresiones thanks!pedro

I am just building the sides of the box of the amplifier currently, where all the I/O will be attatched.

I added a 2K good quality multi-turn potentiometer parallel to each of the 1K resistor to set the bias for class-A and hopefully to reduce the heat on the load resistors.

I will let you know very soon of the results.
PS. I am running it only from batteries.