I'm considering changing the input impedance of my Le Monstre as I want to use it with a DHT pre, and for that I believe I'll need to use a 100K shunt resistor (rather than 47K). Can anyone can advise if this is a silly idea (or not).
I'd also find it really helpful if someone could walk through the input impedance calc for this amp.
I'm trying to understand why JLH chose a 1K2 input series resistor, rather than 1K. Is this front end really that different to any of the Pass designs (M2 etc).
Many thanks
I'd also find it really helpful if someone could walk through the input impedance calc for this amp.
I'm trying to understand why JLH chose a 1K2 input series resistor, rather than 1K. Is this front end really that different to any of the Pass designs (M2 etc).
Many thanks
Hello,
Very probably Jean Hiraga tried some values for the gate stopper and 1K2 worked a tiny bit better than the others.
For the 47k is probably the value that works the best in most situation. Of course of you have a preamp with high output impedance raising it will give better results.
Greetings Eduard
Very probably Jean Hiraga tried some values for the gate stopper and 1K2 worked a tiny bit better than the others.
For the 47k is probably the value that works the best in most situation. Of course of you have a preamp with high output impedance raising it will give better results.
Greetings Eduard
Hello,
But you will probably not hear it if you build this circuit with other transistors than the ones Hiraga used. Same with the 20 and 30 watt class A design. The original design was all about something " magical " with the the chosen parts. If there are 6 or 8 transistors and you end up using different ones it wont be what the designer intended it to be.
I remember reading a review of the 20 or 30 watt Hiraga in a German magazine and the reviewer was questioning if someone did put some kind of illegal substance in his drink because the imaging he got was so holographic. Surely you wont get that with a sub standard supply and just throwing in some transistor equivalents.
Greetings, Eduard
P.s if i go back to solid state i would go towards Nelson Pass and use parts used during the designing proces.
Greetings Eduard
But you will probably not hear it if you build this circuit with other transistors than the ones Hiraga used. Same with the 20 and 30 watt class A design. The original design was all about something " magical " with the the chosen parts. If there are 6 or 8 transistors and you end up using different ones it wont be what the designer intended it to be.
I remember reading a review of the 20 or 30 watt Hiraga in a German magazine and the reviewer was questioning if someone did put some kind of illegal substance in his drink because the imaging he got was so holographic. Surely you wont get that with a sub standard supply and just throwing in some transistor equivalents.
Greetings, Eduard
P.s if i go back to solid state i would go towards Nelson Pass and use parts used during the designing proces.
Greetings Eduard
we were speaking about gate resistors value, and resistor defining Rin of an amp, not substitution for active parts
now, I'm lucky, had my time with Elephants, and they're notoriously pranking buggers, so my ears are farted enough that I can't hear what I say is hard to hear
judging entire world by my own measure ...... yes - why not
now, I'm lucky, had my time with Elephants, and they're notoriously pranking buggers, so my ears are farted enough that I can't hear what I say is hard to hear
judging entire world by my own measure ...... yes - why not
Hello,
I have all the French publications written by Hiraga. And after the initial articles he and other writers start publishing about different supplies. The last one in the series was about old style big car batteries that would allow about 3 hours listening. Of course now the batteries have higher energy density, even use different technologies or you could try big supercaps. The last ones probably need to be connected to the grid to keep them charged because they will run empty to fast.
Certainly would be something that i would consider if i would built this French flagship.
Greetings Eduard
I have all the French publications written by Hiraga. And after the initial articles he and other writers start publishing about different supplies. The last one in the series was about old style big car batteries that would allow about 3 hours listening. Of course now the batteries have higher energy density, even use different technologies or you could try big supercaps. The last ones probably need to be connected to the grid to keep them charged because they will run empty to fast.
Certainly would be something that i would consider if i would built this French flagship.
Greetings Eduard
At the time, an input impedance of 47k was considered the "standard" for line preamplifiers and power amplifiers.
Since this is a jFET input stage and jFETs have a very large gate to source impedance, you can safely raise the value of the 47k input resistor on the expense of a slightly raised input noise.
10k over 10k is a -6dB divider. Most sources (this day) can drive line loads down to 10k without issues. (This example yields to 20k.)
But why? Why reducing this allmighty full musclepower 2 x 8W (!) golden sunrise Kundalini class A amplifier?
Bad vibes? Barking dogs? Angry neighbours? Aliens descending? All of them? Beats me.
Rin resistor can be placed first and then gate stopper after
in fact, that arrangement is more common, even if with moderate value of gate stopper there is no practical difference, neither technical nor auditive
in that case is avoided getting signal divider
anyhow- value of gate stopper is in conjunction with overall circuit construction - as example - last iteration of F5 from Pa (F5m, this years BAF presentation) is having gate stopper of 22K
Pa simply shaped Hf amp behavior with that value, avoiding need for compensation caps in NFB loop
in fact, that arrangement is more common, even if with moderate value of gate stopper there is no practical difference, neither technical nor auditive
in that case is avoided getting signal divider
anyhow- value of gate stopper is in conjunction with overall circuit construction - as example - last iteration of F5 from Pa (F5m, this years BAF presentation) is having gate stopper of 22K
Pa simply shaped Hf amp behavior with that value, avoiding need for compensation caps in NFB loop
…at 27k for that matter, which would give something closer to the intended Rin.
I've been experimenting with various resistor values on the Le Monstre inputs. I'm now at 3K series and 220K shunt., I think this is about as far as is sensible.
The hiss from my DHT pre is greatly reduced, but it's still there.
This pre is silent into an M2/ LuDEF. What's going on here that I've missed? Is it just the case that the pre has too much gain for the power amp?
Thanks
The hiss from my DHT pre is greatly reduced, but it's still there.
This pre is silent into an M2/ LuDEF. What's going on here that I've missed? Is it just the case that the pre has too much gain for the power amp?
Thanks
we were speaking about gate resistors value, and resistor defining Rin of an amp, not substitution for active parts
now, I'm lucky, had my time with Elephants, and they're notoriously pranking buggers, so my ears are farted enough that I can't hear what I say is hard to hear
judging entire world by my own measure ...... yes - why not
We don't age, we develop better frequency response.