If you are still around, could you post the schematic of Selectronic's Profet amp?
They sell only finished units now.
This is true, but depends on the output transistors used. I guess that you are using some of the biggest ones from on semi, which have the sweet spot around 1.1A, but also like more VOLTAGE (unless you cascode them).
I didnt check the datasheets, but I'm pretty sure that the original ones chosen by Hiraga were doing their best at 20W output power, or he would just have proposed a 30W amp
The outputs chosen were not very high powered; the maximum power depends on the heatsink thermal resistance.
Additionally: the current amplification is matched with the driver transistors, such that this becomes a combo that performs well.
Even the input pairs must be 'better than' the commonly proposed BC559 type, as the flat shelving of the amplification is needed, that reacts to a difference in the Vce-difference. Hiraga spent quite some time in matching, each choice is tricky.
albert
triode_al, you're right: Hiraga "matched" all transistors.
BTW, I have found these PCB on sale, which seem good:
Leer PCB Super Class A Verstärker Hiraga "L Audiophile" su eBay.it Verstärker, High-End Audiogeräte, Audio Hi-Fi
This scheme has been posted in this thread.
BTW, I have found these PCB on sale, which seem good:
Leer PCB Super Class A Verstärker Hiraga "L Audiophile" su eBay.it Verstärker, High-End Audiogeräte, Audio Hi-Fi
This scheme has been posted in this thread.
I didnt check the datasheets, but I'm pretty sure that the original ones chosen by Hiraga were doing their best at 20W output power, or he would just have proposed a 30W amp
I can confirm that, as I ran a slightly higher voltage and power on my first build and killed the output transistors (and a 12" woofer). The heatsinks were big. Be careful with the bias.
Hi,
I understand some power this little monster from a 12 V regulated supply.
the original Le Monstre (which I built with the selected transistor set from the Maison de l'Audiophile) is intended to run from lead acid batteries as well. This implies that the Vb is higher than 12 V: between 12,6 and 13,2 V is useful.
This slightly more than one volt difference makes a difference in power consumption (current) and details.
albert
I understand some power this little monster from a 12 V regulated supply.
the original Le Monstre (which I built with the selected transistor set from the Maison de l'Audiophile) is intended to run from lead acid batteries as well. This implies that the Vb is higher than 12 V: between 12,6 and 13,2 V is useful.
This slightly more than one volt difference makes a difference in power consumption (current) and details.
albert
Yes Daniel, indeed have heard them on the large Onken loudspeakers with horns, at the 'old' Maison de l'Audiophile in Paris, with William Walther in charge.
And, - Yes, I have tempted to build it for my ESL, but never succeeded far enough (own choice of components, having all bias resistors adjustable till there is a DC equilibrium without feedback applied yet isn't easy). Now I saw the board from the German ebay I might be tempted again to experiment
I do have the 8W (which is not the threads' topic but discussed anyway).
albert
8 W Hiraga implementation
Hi Dan,
here you go:
this is my second implementation with regulated power supply. The first one had passive and in total 12 of those large capacitors.
Note the extra large 1 ohm resistors! They still get hot.
I have decoupled the transistors in the cascade stage with solid tantal caps of 27 micro farad.
I have noted that the quality of the feedback set is very important.
regards
albert
Hi Dan,
here you go:
this is my second implementation with regulated power supply. The first one had passive and in total 12 of those large capacitors.
Note the extra large 1 ohm resistors! They still get hot.
I have decoupled the transistors in the cascade stage with solid tantal caps of 27 micro farad.
I have noted that the quality of the feedback set is very important.
regards
albert
a friend of mine had both versions (not DIY, but commercial versions), the 30W sounds much better, more transparent and powerful at the same time.
Hartmut
what is the power rating of these extra large 1 ohm resistors when you choose to use them without a heatsink?
What is the Rth j-a of the resistor without a heatsink?
Hi Andrew,
these resistors are 50W but in air this is lower. I can't find the thermal resistance in free air - just the derating, which is 35% in such a closed box.
Of course the current is some 750 mA, but the inside of the cabinet reaches easily 35 degrees, and the resistors are some 45 degrees to the touch.
albert
45°C is well within the limits for these
the last two monstres i built one used 5W wire wound at 0.6A and they ran hot to touch.
one used 5W metal film they ran hot to touch also.
le class A is a little nastier running at 2A-2.5A but the whole amp runs hot after an hour or two it is close enough to thermal equilibrium and sounds really nice.
I wish you could still get the sony vfets..... a vfet Monstre would be great....
-Dan
the last two monstres i built one used 5W wire wound at 0.6A and they ran hot to touch.
one used 5W metal film they ran hot to touch also.
le class A is a little nastier running at 2A-2.5A but the whole amp runs hot after an hour or two it is close enough to thermal equilibrium and sounds really nice.
I wish you could still get the sony vfets..... a vfet Monstre would be great....
-Dan
Well, I have a batch of original Toshiba 2SJ55 and 2SK175 - how would that do? Absolute thermal stability and a veritable hot - hot monstre. What do you think?45°C is well within the limits for these
the last two monstres i built one used 5W wire wound at 0.6A and they ran hot to touch.
one used 5W metal film they ran hot to touch also.
le class A is a little nastier running at 2A-2.5A but the whole amp runs hot after an hour or two it is close enough to thermal equilibrium and sounds really nice.
I wish you could still get the sony vfets..... a vfet Monstre would be great....
-Dan
albert
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