Why does the Hiraga 20 Watt use a resistor in the power supply? Well, strange enough, if you leave this resistor out of the circuit, what you get is a (relative) big hum yes, with 408.000 mF or more as caps!!). This effect also appears if you build double mono-pairs (and in the original factory models too). The Monstre does not suffer this problem. I don't know what causes this hum, should work without resistors?
Rudy
Rudy
R/C PSUs
The resistor/cap forms an low pass circuit, filtering out garbage from the PSU, 6dB/Octave. L/C is better, 12dB/Octave. I usually go a Fs=2Hz, but it's not critical. The value of the resistor does become critical with a poweramp due to the high current needs. Stay below 1 ohm and use big caps..
Whether or not the amp is dual mono or multichannel won't affect it.
Le Monstre' shouldn't hum, since it's not connected to the power grid at all! At least not with the battery powered version (and that's the one to build, imho).
Low fedback amps don't have as high CMRR as high feedback amps have. But they sound way better.. imho that is.
It's a problem with high sensitive loudspeakers. Mine are 95dB so I have no probs with any of my amps, tube or transistor, they all no or small amount of feedback amps.
The resistor/cap forms an low pass circuit, filtering out garbage from the PSU, 6dB/Octave. L/C is better, 12dB/Octave. I usually go a Fs=2Hz, but it's not critical. The value of the resistor does become critical with a poweramp due to the high current needs. Stay below 1 ohm and use big caps..
Whether or not the amp is dual mono or multichannel won't affect it.
Le Monstre' shouldn't hum, since it's not connected to the power grid at all! At least not with the battery powered version (and that's the one to build, imho).
Low fedback amps don't have as high CMRR as high feedback amps have. But they sound way better.. imho that is.
It's a problem with high sensitive loudspeakers. Mine are 95dB so I have no probs with any of my amps, tube or transistor, they all no or small amount of feedback amps.
Resistors in the 20W
If you remove these resistors, the amp changes in sound too. The bottom end becomes firmer, but the liquid nature of the amp, which is what I love, vanishes more or less. And the hum level goes up.
The amp doesn't sound very *electronic* to me. Quite the opposite of running a CD player through a console with two hundred crappy opamps and a thousand tantal caps. I work with these 250k$ suckers on a daily basis..
Sorry, that probably didn't make much sense??
It's difficult to describe the sound, isn't it?
I found that any tinkering with the Hiraga 20W changes the sound. I can't *improve it* and I've tried for a decade (curios as I am!). I just luv it like it is. I know some people have changed the output transitors to high current/high speed Sankens or whatever. I just don't like it...
Also, it's definitely not the ONLY amp that rocks my World. I'm not fanatic, I just dig it a lot..
If you remove these resistors, the amp changes in sound too. The bottom end becomes firmer, but the liquid nature of the amp, which is what I love, vanishes more or less. And the hum level goes up.
The amp doesn't sound very *electronic* to me. Quite the opposite of running a CD player through a console with two hundred crappy opamps and a thousand tantal caps. I work with these 250k$ suckers on a daily basis..
Sorry, that probably didn't make much sense??
It's difficult to describe the sound, isn't it?
I found that any tinkering with the Hiraga 20W changes the sound. I can't *improve it* and I've tried for a decade (curios as I am!). I just luv it like it is. I know some people have changed the output transitors to high current/high speed Sankens or whatever. I just don't like it...
Also, it's definitely not the ONLY amp that rocks my World. I'm not fanatic, I just dig it a lot..
Solstice,
I have also built the Hiraga and was very impressed with it and I agree with all your observations. Unfortunately I cannot use it now due to the speakers I use.
I would like to know if you are familar with this amplifier
http://perso.wanadoo.fr/jm.plantefeve/schePP.html
which is also a French design,and a version is available in kit form.(Selectronic-GrandMos)
I have noticed that current feedback designs like these are very fast and tend to have a very clean and open high end.
Jam
[Edited by jam on 06-08-2001 at 03:42 PM]
I have also built the Hiraga and was very impressed with it and I agree with all your observations. Unfortunately I cannot use it now due to the speakers I use.
I would like to know if you are familar with this amplifier
http://perso.wanadoo.fr/jm.plantefeve/schePP.html
which is also a French design,and a version is available in kit form.(Selectronic-GrandMos)
I have noticed that current feedback designs like these are very fast and tend to have a very clean and open high end.
Jam
[Edited by jam on 06-08-2001 at 03:42 PM]
MosFet Amps..
Hi Jam!
No, don't know that one. I haven't really done a lot with MosFets, 'cept some experimental Pass tinkering. This forum have however poked my curiousity, so I guess I'll look into those MosFets.
I do mostly designs for pro/recording use, but there are many similarities between hifi and that stuff.. microphone preamps have a lot in common with MC/RIAAs for instance.
Try convincing a pro about that though.. haha. They're so bloody conservative!
I've found the Hiraga 20W to quite capable of driving insufficient loudspeakers, like Snell Es, 87dB, which I used to own some years back. As long as the load isn't too difficult it's okay. Better than single ended triodes running close to max. I've also used it with Quads, the old ones as well, and that was also a happy marriage, imho.
Hi Jam!
No, don't know that one. I haven't really done a lot with MosFets, 'cept some experimental Pass tinkering. This forum have however poked my curiousity, so I guess I'll look into those MosFets.
I do mostly designs for pro/recording use, but there are many similarities between hifi and that stuff.. microphone preamps have a lot in common with MC/RIAAs for instance.
Try convincing a pro about that though.. haha. They're so bloody conservative!
I've found the Hiraga 20W to quite capable of driving insufficient loudspeakers, like Snell Es, 87dB, which I used to own some years back. As long as the load isn't too difficult it's okay. Better than single ended triodes running close to max. I've also used it with Quads, the old ones as well, and that was also a happy marriage, imho.
For grataku..
Doh! I re-read your post(s) and I see why you want to drop the voltage and not use another powertrannie..
I wouldn't use bigger resistors/inductors with a high DC resistance, that'll soften up the bottom end too much, I reckon. I'm not sure what to do? Why not just adjust the schematic to accept the higher voltages? You'll also get more power out, something close to 35W. Your choice of output transistors should be able to take the heat, so to speak..
Doh! I re-read your post(s) and I see why you want to drop the voltage and not use another powertrannie..
I wouldn't use bigger resistors/inductors with a high DC resistance, that'll soften up the bottom end too much, I reckon. I'm not sure what to do? Why not just adjust the schematic to accept the higher voltages? You'll also get more power out, something close to 35W. Your choice of output transistors should be able to take the heat, so to speak..
Wow,
this thread still gets a lot of attention!
Briefly:
*grataku, if you need a voltage drop, why not use a transformer with a lower output voltage?*
It's something related to cash (or the lack thereof)
*If you remove these resistors, the amp changes in sound too. The bottom end becomes firmer, but the liquid nature of the amp, which is what I love, vanishes more or less. And the hum level goes up.*
The more I think about this liquid nature the more I am convinced that the liquidity comes from the amps relying on the post R caps alone for energy.
*If there's anyone out there with a copy of L'audiophile with Hiraga's constructions/articles I'll gladly pay for a nice photocopy*
I most definitely subscribe to that, I think I know enough french to read it, too. If not I can learn the rest!
On the literature note, since you're from Europe, I wonder if you know an Italian audio designer by the name of Aloia. That is another of my all time favorite designers. I wish I could put my hands on some of his old 80's articles. Back then he was very active in solid state design. He moved more toward valves in the 90's. He was playing around with zero feedback designs way before the Danish came along.
this thread still gets a lot of attention!
Briefly:
*grataku, if you need a voltage drop, why not use a transformer with a lower output voltage?*
It's something related to cash (or the lack thereof)
*If you remove these resistors, the amp changes in sound too. The bottom end becomes firmer, but the liquid nature of the amp, which is what I love, vanishes more or less. And the hum level goes up.*
The more I think about this liquid nature the more I am convinced that the liquidity comes from the amps relying on the post R caps alone for energy.
*If there's anyone out there with a copy of L'audiophile with Hiraga's constructions/articles I'll gladly pay for a nice photocopy*
I most definitely subscribe to that, I think I know enough french to read it, too. If not I can learn the rest!
On the literature note, since you're from Europe, I wonder if you know an Italian audio designer by the name of Aloia. That is another of my all time favorite designers. I wish I could put my hands on some of his old 80's articles. Back then he was very active in solid state design. He moved more toward valves in the 90's. He was playing around with zero feedback designs way before the Danish came along.
Like I said, I dig Hiraga's stuff..
Yeah, I get the cash thing. Hence my use of powertrannies for inductors. Get's awfully exspensive with ten in an amp..
And yes, the caps close to the amp are the most critical. I discovered that when I fixed that 20W with GE caps mentioned before.
But a 18V drop would require very large resistors and that will affect the performance in a negative way.
No, I don't know many hifi designers in Europe. I can tell you all about the stuff from LC Audio though.. http://www.lcaudio.dk ..
My work, hobby.. and life I geuss evolves around music and making music. I know a lot of pro audio/recording designers, but that won't help much with your amp.
I'm trying to improve my whole chain of recording gear, including my monitoring rig. Pro gear suck ***, imho.
And it's the same gear I use for listening to my CDs, vinyls, 1/2", 24 bit 96k stuff, DATs.. blah blah..
Btw, LC Audio is the offspring of a LOT of articles/DIY constructions in the danish hifi mag "High Fidelity". The guy used to write/work for the mag.
They did a lot of non feedback stuff in the 80s as well, before LC Audio was born. "The End" amp is actually from that mag and not LC Audio.
A lot of the articles was inspired by... Hiraga.
The circle is closed.
Yeah, I get the cash thing. Hence my use of powertrannies for inductors. Get's awfully exspensive with ten in an amp..
And yes, the caps close to the amp are the most critical. I discovered that when I fixed that 20W with GE caps mentioned before.
But a 18V drop would require very large resistors and that will affect the performance in a negative way.
No, I don't know many hifi designers in Europe. I can tell you all about the stuff from LC Audio though.. http://www.lcaudio.dk ..
My work, hobby.. and life I geuss evolves around music and making music. I know a lot of pro audio/recording designers, but that won't help much with your amp.
I'm trying to improve my whole chain of recording gear, including my monitoring rig. Pro gear suck ***, imho.
And it's the same gear I use for listening to my CDs, vinyls, 1/2", 24 bit 96k stuff, DATs.. blah blah..
Btw, LC Audio is the offspring of a LOT of articles/DIY constructions in the danish hifi mag "High Fidelity". The guy used to write/work for the mag.
They did a lot of non feedback stuff in the 80s as well, before LC Audio was born. "The End" amp is actually from that mag and not LC Audio.
A lot of the articles was inspired by... Hiraga.
The circle is closed.
Aloia
I did a google on him (+Aloia +schematic) and found lotsa nice stuff.. busy man!
Mostly tube stuff though. I'm not much into tube power amps (I have a 845 amp and some 300Bs somewhere I oughtta use some time), but I do make a lot of other stuff with tubes.
Ohh yeah, and tube geetar amps.. but that's hardly high fidelity.. haha.
I did a google on him (+Aloia +schematic) and found lotsa nice stuff.. busy man!
Mostly tube stuff though. I'm not much into tube power amps (I have a 845 amp and some 300Bs somewhere I oughtta use some time), but I do make a lot of other stuff with tubes.
Ohh yeah, and tube geetar amps.. but that's hardly high fidelity.. haha.
Solstice,
is 18% drop so 24V from 29V. I could just use the 29V directly, although that would leave me with a simple capacitor as the power supply and the ripple noise that someone was reporting. Power dissipation wouldn't be a problem: in the PS or in the amp the power needs to get dissipated somehow.
Aloia:
there is VERY little available on the net compared to what the guy has done in the past. He apparently does not believe in the web. I used to have a whole lot of articles from the 80's most of which are gone.
is 18% drop so 24V from 29V. I could just use the 29V directly, although that would leave me with a simple capacitor as the power supply and the ripple noise that someone was reporting. Power dissipation wouldn't be a problem: in the PS or in the amp the power needs to get dissipated somehow.
Aloia:
there is VERY little available on the net compared to what the guy has done in the past. He apparently does not believe in the web. I used to have a whole lot of articles from the 80's most of which are gone.
Transformer
The 18V drop came from my misreading.. sorry. I thought you had a 2x30VAC transformer, but that's the rectified voltage. In fact you'll be using a 2x21,5VAC!
You could use two smaller caps, before the resistor, and use the big ones after. This is a common preactice I believe. I would just live with the higher voltage and adjust the amp to fit and enjoy the higher wattage.
I did find quite a few Aloia schematics/sites, but they're not his own (sites). *Fan* sites I guess.
Same thing with Hiraga. He used to be the editor of L'audiophile.. I don't even know if that mag exists anymore.
I'd luv to hear what he's up to if he's still around (I HOPE so..!!)
I have some articles but they're in danish and mostly about his tube designs.
Anyone else got any info?? His Le Monstre' article does cover some of his PSU philosophies, including noise/ripple measurements of battery PSUs.
The 18V drop came from my misreading.. sorry. I thought you had a 2x30VAC transformer, but that's the rectified voltage. In fact you'll be using a 2x21,5VAC!
You could use two smaller caps, before the resistor, and use the big ones after. This is a common preactice I believe. I would just live with the higher voltage and adjust the amp to fit and enjoy the higher wattage.
I did find quite a few Aloia schematics/sites, but they're not his own (sites). *Fan* sites I guess.
Same thing with Hiraga. He used to be the editor of L'audiophile.. I don't even know if that mag exists anymore.
I'd luv to hear what he's up to if he's still around (I HOPE so..!!)
I have some articles but they're in danish and mostly about his tube designs.
Anyone else got any info?? His Le Monstre' article does cover some of his PSU philosophies, including noise/ripple measurements of battery PSUs.
I have 3 pages from the original 20/30W article, it includes a stuffing guide for the originl Kanéda design Hiraga adapted, it was good enough for me to reconstruct the schematic, below is an ascii version.<pre><font face="Courier new">
+-----+-----+---+-{2k2}-+----+-------------+- +25V
| | | | | __|__ |
| | | | | ( ) D33A 1
_|_ __|__R | | | | R
2n2___ /Z\ D | | | 3 |
| | 9 | | 2 k 2SA634 |
| | A 8 | K 3 C 2
+-----+ K | 2 | E--B S
| 2 | +----+-------B E D
| | | | C | 1
GND | | C | | 8
+---(------B 2SC815 +----+ 8
| | E | |
2 | | | |
4 | | 1 |
0 | | K |
R | | | |
| | | | |
+---B E C-(-+ | | |
| 2SA539 | | | | |
| | | 5 | |
-{4k7}-+---+ | | 0--+-{200R}---+----+--
| | | | 0 | | |
1 | 2SC815 / | | 1 | |
0 +---B E C / | 0 | |
k | | | R | |
| | | | | | |
GND 2 | | GND | |
4 | | 1 |
0 | | K |
R | | | |
| | E | |
+----(-----B 2SA539 +----+
| | C | |
| | | C |
| | +----+------B E 2
GND 8 | | | E--B S
| k | 2 3 C A
+-----+ 2 | k K 2SC1096 | 6
| | | | 2 3 1 2
_|_ __|__R | | | | R
2n2___ /Z\ D | | | __|__ |
| | 9 | | | ( ) D33A |
| | A | | | | |
+-----+-----+----+-{2k2}+----+-------------+ -25V</font></pre>
RD9A = 1N4739A
D33A = constant current Diode ?
Sorry about the double spacing its the HTML formatter on the forum?
Cut and paste in to notepad and it should look better.
I have copies of the articles for the Le Monstre and L'almimentation, totals about 20 pages.
Also have 3 pages for the "Le Preamplificateur Kaneda",
the psu for the pre has 6x 12volt batteries to give +/-36V plus 2 x 22,000uF followed by 3x 100,000uF per rail!
Unfortunatly I don't have a scanner, maybe soon?
<b>solstice</b> as you are into studio equipment you may find these links of interest, both are from DC RECORDING HOME PAGE in Japan
Mosfet DAC Buffer
http://www.asahi-net.or.jp/~uu4t-mur/MYAMP/MUHCPRE.htm
he says this appeared in Sidewinder MJ Magazine
Unbalanced to balnced convertor
http://www.asahi-net.or.jp/~uu4t-mur/DOWNLD/UB_B_CONV.pdf
Both seem to be inspired by Kaneda Circuits
Regards James
+-----+-----+---+-{2k2}-+----+-------------+- +25V
| | | | | __|__ |
| | | | | ( ) D33A 1
_|_ __|__R | | | | R
2n2___ /Z\ D | | | 3 |
| | 9 | | 2 k 2SA634 |
| | A 8 | K 3 C 2
+-----+ K | 2 | E--B S
| 2 | +----+-------B E D
| | | | C | 1
GND | | C | | 8
+---(------B 2SC815 +----+ 8
| | E | |
2 | | | |
4 | | 1 |
0 | | K |
R | | | |
| | | | |
+---B E C-(-+ | | |
| 2SA539 | | | | |
| | | 5 | |
-{4k7}-+---+ | | 0--+-{200R}---+----+--
| | | | 0 | | |
1 | 2SC815 / | | 1 | |
0 +---B E C / | 0 | |
k | | | R | |
| | | | | | |
GND 2 | | GND | |
4 | | 1 |
0 | | K |
R | | | |
| | E | |
+----(-----B 2SA539 +----+
| | C | |
| | | C |
| | +----+------B E 2
GND 8 | | | E--B S
| k | 2 3 C A
+-----+ 2 | k K 2SC1096 | 6
| | | | 2 3 1 2
_|_ __|__R | | | | R
2n2___ /Z\ D | | | __|__ |
| | 9 | | | ( ) D33A |
| | A | | | | |
+-----+-----+----+-{2k2}+----+-------------+ -25V</font></pre>
RD9A = 1N4739A
D33A = constant current Diode ?
Sorry about the double spacing its the HTML formatter on the forum?
Cut and paste in to notepad and it should look better.
I have copies of the articles for the Le Monstre and L'almimentation, totals about 20 pages.
Also have 3 pages for the "Le Preamplificateur Kaneda",
the psu for the pre has 6x 12volt batteries to give +/-36V plus 2 x 22,000uF followed by 3x 100,000uF per rail!
Unfortunatly I don't have a scanner, maybe soon?
<b>solstice</b> as you are into studio equipment you may find these links of interest, both are from DC RECORDING HOME PAGE in Japan
Mosfet DAC Buffer
http://www.asahi-net.or.jp/~uu4t-mur/MYAMP/MUHCPRE.htm
he says this appeared in Sidewinder MJ Magazine
Unbalanced to balnced convertor
http://www.asahi-net.or.jp/~uu4t-mur/DOWNLD/UB_B_CONV.pdf
Both seem to be inspired by Kaneda Circuits
Regards James
Very interesting!
Thank you tvi...!!
I have the Le Monstre' article but it's a re-print of swedish article translated into danish. I don't have any original french L'audiophile stuff, unfortunally.
If you would be so kind to take a photocopy (colour would be nice), instead of a scan (which is what I prefer), I would be eternally greatfull. Just name your price.. (it's faster & cheaper if I just snail mail you the money in an envelope. What currency? Let me know if you need my emailadr.)
And thanx for the links too!
I'm about to make a A/D converter, not the other way 'round which is what you folks do here.
But I'll need some tips anyway..
Thank you tvi...!!
I have the Le Monstre' article but it's a re-print of swedish article translated into danish. I don't have any original french L'audiophile stuff, unfortunally.
If you would be so kind to take a photocopy (colour would be nice), instead of a scan (which is what I prefer), I would be eternally greatfull. Just name your price.. (it's faster & cheaper if I just snail mail you the money in an envelope. What currency? Let me know if you need my emailadr.)
And thanx for the links too!
I'm about to make a A/D converter, not the other way 'round which is what you folks do here.
But I'll need some tips anyway..
tvi / James
Would you please check the schematic that you kindly posted above. As shown, the 1k resistors near the output are shorted. I suspect that they should be connected from the driver collector (output device base, see below) to the opposite supply rail, rather than the feedback path as shown.
Also, the compound pair output transistors do not appear to be correct. Should not the driver collector be connected to the output base and the driver emitter to the output collector?
If anyone knows what a D33A is I'd be glad to hear.
Geoff
Would you please check the schematic that you kindly posted above. As shown, the 1k resistors near the output are shorted. I suspect that they should be connected from the driver collector (output device base, see below) to the opposite supply rail, rather than the feedback path as shown.
Also, the compound pair output transistors do not appear to be correct. Should not the driver collector be connected to the output base and the driver emitter to the output collector?
If anyone knows what a D33A is I'd be glad to hear.
Geoff
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