No. It is better to balance the output offset by the 100R trim pot.
I wrote that it is preferable to match them close. But it will work sturdy, even if you don't. I don't talk about a heavy mismatch.
Sorry for spamming the thread: Can someone send me the link to a pcb most people are using here??? Want to etch my own PCBs...
Thanks, Dirk
Thanks, Dirk
Hey, i just bought a "le monstre" 12v version, does anyone have any opinions of this ? when i get it ill share more close up pics. and also can anyone recommend the right kind of 12v battery that's not too big (like car batterys are). ill be using this in a car in future but for now want to power it at home so just need a PSU or battery or both so it can be charged. I don't realy have an idea!
Car Amplifier Class A, 2x20W (J .Hiraga schematic) no audison, brax, dls | eBay
Thanks 🙂
Car Amplifier Class A, 2x20W (J .Hiraga schematic) no audison, brax, dls | eBay
Thanks 🙂
I am powering my le monstre only from batteries. See here Le monstre
Oh and something else, the "le monstre" is 8W, not 20W.
Your site is brilliant! i found it the other day too thankyou, very helpfull!
i thought that there are some variations of the "le monstre" on the internet.
If you see the pictures on the ebay link i posted you'll see the terminals of this amplifier say
GND
REM
+12v
So i presume that is not "dual rail" and this amp must be based on the
"le monstre" but not the same as the original.
GND
REM
+12v
So i presume that is not "dual rail" and this amp must be based on the
"le monstre" but not the same as the original.
Could someone please identify which version of the amp i have ? and any details about it, upgrade ideas ....
thankyou
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
thankyou
Last edited:
I'm in doubt that your amp really runs class A up to 20W.
At an idle current of 1A and +- 21V supply rails the amp would draw more than 40W per channel (= total 84W). That would be too much power dissipation for the unsufficiant heat sinking capabilities of your amp's casing (I can't see any fans in your pictures).
So I believe it has a class AB setting to lower the power dissipation of the output transistors of the amp and the pulsed supply.
At an idle current of 1A and +- 21V supply rails the amp would draw more than 40W per channel (= total 84W). That would be too much power dissipation for the unsufficiant heat sinking capabilities of your amp's casing (I can't see any fans in your pictures).
So I believe it has a class AB setting to lower the power dissipation of the output transistors of the amp and the pulsed supply.
I am not sure if it is the 20W version but I am sure that is has some kind of dc-dc converter so that it feeds the amplifier with a dual rail supply out of a single 12v one.
Probably based on Le Monstre topology and could be good enough in a car. Interesting input stage with TO220 drivers! The overheat protection makes sense. Also it may be workking in class for the first watts only. splitted PSU is very bad in audio. Good enough for a car maybe.
Also nothing special in components, I can see some 5% carbon resistors and some inductive power bricks.
Hi, i imagine so the heatsinks do seem rather small, unless of corse the amp is biased low maybee ? there are no fans indeed. so you mean it would be "class a" for low power levels then when its cranked up it would go into B ?
one thing ive always wanted to know how would one test if an amp like this is in b or a ?
Im pretty sure it has "dc-dc converter" too.
"splitted PSU is very bad in audio. Good enough for a car maybe. " yeah id rather have 2 x 12v batterys. but i can see there is no point remaking the PSU for this thing as it would be a shame to take apart something that works.
well ill have a listen and see how it is and if i don't want it i might upgrade some of those components and/or sell it on. it cost me £80 with post and packaging, not bad realy.
Cheers
Last edited:
ahh another question, what kind of lead acid battery would you use with this ? u think i can get away with less than 40ah. can always try i guess. and does anyone know a good charger circuit or kit to charge 12v battery.
The 2 x 45Ah used on Le Monstre last less than 3 hours. You can use the battery of you car to make a try 30 minutes. A 4Ah charger costs less than 50 euros (maybe 30 in DIY. Many schematics on the net.)
You can't use the car battery for that long if the engine is not switched on. You must use deep cycle SLA batteries or switch the engine on, or else the car battery will be damaged.
Measure the voltage drop across the .47Ohm resistors. Ohm's law: R=U/I; I= U/R; Iidle=Udrop voltage/.47. The amp is working class A up to 20W if idled by approx. 1A. The lower the current, the earlier the amp slips to class B.
The power supply is a pulsed two-rail type. Correctly dimensioned, it should measure at least +-20V. It converts the 12V battery voltage to 2 x 21V.
The topology of the 20W Hiraga is not at all identical to Le Monstre.
80 GBP is a very reasonable price though...
I built the 20W version a few years back. I remember liking its midrange very much. Bass-wise it was not the best match for my ATCs. Not sure if its a good fit for a car amp.
this amp has a DC-DC converter. that is for sure. wich also need much of the heatsinks. i guess it is low bias. and 2x20W calss A/B. and maybe 2x2.5W classA.
20W class A at 4 ohm. will demand over 3A bias. and at +/-21V that is above 126W dissipation pr ch😀 pluss all that the DC-DC supply dissepates.
so a total of around 300W😀 not very likely😀
BTW: it is a cheap amp that is scraped, and used the chassis and the DC-DC supply from that amp.
but it looks good🙂 however. there is not mutch classA power in this.
20W class A at 4 ohm. will demand over 3A bias. and at +/-21V that is above 126W dissipation pr ch😀 pluss all that the DC-DC supply dissepates.
so a total of around 300W😀 not very likely😀
BTW: it is a cheap amp that is scraped, and used the chassis and the DC-DC supply from that amp.
but it looks good🙂 however. there is not mutch classA power in this.
Last edited: