Hello all,
I still have a few Hitachi MosFet's lying around. They are 4x n-channel, 4 p-channel. I understand those are rather old and were used in the mid 80'ies. So I'm thinking to put them to work and build an AMP out of them. Does anybody know a good quality circuit with discrete Parts (no IC, chips - op amp) for them?
Thanks
I still have a few Hitachi MosFet's lying around. They are 4x n-channel, 4 p-channel. I understand those are rather old and were used in the mid 80'ies. So I'm thinking to put them to work and build an AMP out of them. Does anybody know a good quality circuit with discrete Parts (no IC, chips - op amp) for them?
Thanks
Thanks Jackand08,
Nice Job finding those
I remember that a friend rebuilt some design from the Elektor Magazine back in the 80's. I think it was called the "Crecendo". But he had massive trouble with self oscillations maybe due to some inductive parts used or simply because of a weak design. I wonder if the schematics is one of those?!
Reg.
Conehead
Nice Job finding those
I remember that a friend rebuilt some design from the Elektor Magazine back in the 80's. I think it was called the "Crecendo". But he had massive trouble with self oscillations maybe due to some inductive parts used or simply because of a weak design. I wonder if the schematics is one of those?! Reg.
Conehead
You're welcome.
Yes, you're right, if you follow the link to the forum post, one of them is the crescendo (the bottom picture posted) and the other is the mini-crescendo (the top picture posted) with 140 and 70 watt outputs respectively.
I do remember as I was looking round for the schematics, there was a mention about the amp not being very stable and not even a particularly good amp anyway but that's not to say that you could try building one. The link to the forum post in my previous post has a bit more information and some opinions about the amp.
Yes, you're right, if you follow the link to the forum post, one of them is the crescendo (the bottom picture posted) and the other is the mini-crescendo (the top picture posted) with 140 and 70 watt outputs respectively.
I do remember as I was looking round for the schematics, there was a mention about the amp not being very stable and not even a particularly good amp anyway but that's not to say that you could try building one
. The link to the forum post in my previous post has a bit more information and some opinions about the amp.
It probably wasn't that stable as there was no dominant pole It relied on the input capacitance of the mosfets to reduce the gain at high frequencies, not a clever idea imo as these vary due to voltage accross the devices.
Increase the open loop gain & give the thing a pair of drivers for the mosfets & a couple of miller capacitors & it should be fine
I always fancied building the crescendo, never got round to it though, then went off in another direction entirely
It relied on the input capacitance of the mosfets to reduce the gain at high frequencies, not a clever idea imo as these vary due to voltage accross the devices.Increase the open loop gain & give the thing a pair of drivers for the mosfets & a couple of miller capacitors & it should be fine
I always fancied building the crescendo, never got round to it though, then went off in another direction entirely
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Looks like the amp that Maplin sold loads of kits of
E2A:- Vas transistors are different though, Maplin used Japanese components in the Vas, the rest including component values looks identical though
The soundcraftsmen PCR800 use 2 pairs of K135/J50's for 205wpch at 8 ohms and was a very well regarded amp. even beat out the Adcom 555 in audio magazine. it is an easy to build amp. simple circuit.
http://www.diyaudio.com/forums/solid-state/53737-soundcraftsmen-troubles.html
Zc
http://www.diyaudio.com/forums/solid-state/53737-soundcraftsmen-troubles.html
Zc
The Lang 20 watt class A used them, the design is in "Audio Amateur Power Amp Projects" page 128. Not built it but have been tempted once or twice it looks a reasonable design.
I designed this specifically for lateral FET's.
It's easy to build, super stable, and I'm still more than happy 5 or six years down the line with it. What makes this unique is that it has a single ended input stage, which overcomes the main problem of the long tailed pair which is odd harmonic distortion that the ear finds unpleasant and unmusical. The opamp is not in the audio path...
It's used with B&W 703's and sounds... well it's all in the thread,
http://www.diyaudio.com/forums/solid-state/119151-my-mosfet-amplifier-designed-music.html
It's easy to build, super stable, and I'm still more than happy 5 or six years down the line with it. What makes this unique is that it has a single ended input stage, which overcomes the main problem of the long tailed pair which is odd harmonic distortion that the ear finds unpleasant and unmusical. The opamp is not in the audio path...
It's used with B&W 703's and sounds... well it's all in the thread,
http://www.diyaudio.com/forums/solid-state/119151-my-mosfet-amplifier-designed-music.html
I think R15 ( Zobel ) should be 10 Ohm and not 10 kOhm....
C3 could be 4.7 uF. In the schematic it says 47 uF.
Consider one of the earlier Borbely amps.
The DC100 not the DC100A is very nice.
There were two earlier designs too, one was the Servo 50, the other I think was DC coupled at the same power level...
Proven, and properly implemented they sound very nice.
Published in Europe and also in the USA by Audio Amateur.
_-_-bear
The DC100 not the DC100A is very nice.
There were two earlier designs too, one was the Servo 50, the other I think was DC coupled at the same power level...
Proven, and properly implemented they sound very nice.
Published in Europe and also in the USA by Audio Amateur.
_-_-bear
Hello all, thank you for your participation and suggestions.
So far I quite like the Soundcraftsmen AMP. Interesting design but one pair to many output Fet's to build a stereo amp from! I only have 4 and 4 availeble!
Can someone simply just omit one pair in the outputstage for the cost of less power? I found some designs myself and would appreciate if any one could comment on those. I seem to keep stumbling across David Tilbrook design when searching for those Hitachi lateral Mosfet Amp designs. What do you think of the AEM6000 or 6005?
I also found this one A HiFi Power Amp
which apparently is a variation of the AEM6000. Schematic is this one but uses substitute End Fet's that could be replaced by the SJ50 and Sk135...
The creator also speaks about replaceing the rather old MJE340/350 with faster Toshiba types.
cheers...
Conehead
So far I quite like the Soundcraftsmen AMP. Interesting design but one pair to many output Fet's to build a stereo amp from! I only have 4 and 4 availeble!
Can someone simply just omit one pair in the outputstage for the cost of less power? I found some designs myself and would appreciate if any one could comment on those. I seem to keep stumbling across David Tilbrook design when searching for those Hitachi lateral Mosfet Amp designs. What do you think of the AEM6000 or 6005?
I also found this one A HiFi Power Amp
which apparently is a variation of the AEM6000. Schematic is this one but uses substitute End Fet's that could be replaced by the SJ50 and Sk135...
An externally hosted image should be here but it was not working when we last tested it.
The creator also speaks about replaceing the rather old MJE340/350 with faster Toshiba types.
cheers...
Conehead
Most of the soundcraftsmen amps used 2 pairs of K135/J50's for 205wpch @ 8 and 300wpch @ 4 and 450wpch @ 2ohms!!!
the Pro versions used 3 pairs of mosfets for extra SOA but 2 pairs is plenty enough. these have very high gate capacitance. 1 pair would sound better than 2, 2 better than 3 etc.
I like that the SC amps use the 2N3440 and MM4003 devices as drivers. lots of current there. many designers overlooked the need for current in the driver stage for the early mosfet designs. the hitachi devices need a lot esp at high frequencies! I suspect thats one reason why i like the SC amps vs other amps that use the same output devices.
It would be interesting to build up 2 sets of boards with higher current drivers in one set and listen to the differences.
Zc
the Pro versions used 3 pairs of mosfets for extra SOA but 2 pairs is plenty enough. these have very high gate capacitance. 1 pair would sound better than 2, 2 better than 3 etc.
I like that the SC amps use the 2N3440 and MM4003 devices as drivers. lots of current there. many designers overlooked the need for current in the driver stage for the early mosfet designs. the hitachi devices need a lot esp at high frequencies! I suspect thats one reason why i like the SC amps vs other amps that use the same output devices.
It would be interesting to build up 2 sets of boards with higher current drivers in one set and listen to the differences.
Zc
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