Tube/Mosfet 100W Hybrid Amplifier

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This is circuit of Counterpoint SA100.
 

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With all due respect, if you had EVER had anything to do with that amplifier, you would be ashamed to post it's schematic here. It's notoriously unreliable and simply put, badly engineered (if you could call that design proces enginering) - and with all due respect to the moderators, it's been said multiple times.
It is time for this schematic to be forgotten!

And yes, i have experience with this particular amp as well as with 3 other hybrids, and one of my own design. The point of designing it was that the other 3 were just not that good.
 
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With all due respect, if you had EVER had anything to do with that amplifier, you would be ashamed to post it's schematic here. It's notoriously unreliable and simply put, badly engineered (if you could call that design proces enginering) - and with all due respect to the moderators, it's been said multiple times.
It is time for this schematic to be forgotten!

And yes, i have experience with this particular amp as well as with 3 other hybrids, and one of my own design. The point of designing it was that the other 3 were just not that good.
Thank U for information, I have no expirience with this amplifier. Any link?
Regards Mile
 
I mean IRFP240/9240 are not really complementary devices, it sound horribile in mosfet amp...... BJT Design Sound better compare to IRFP240/9240

we have test it in Mosfet amp and in my opinion IRFP240/9240 is no go in mosfet amp
Very strong opinion, but I do some blind test: with same VAS on both channel useing 2SC5200/2SA1943 on left, and IRFP240/IRFP9240 on right channel.
Result:
Nobody hear difference.
 
I mean IRFP240/9240 are not really complementary devices, it sound horribile in mosfet amp...... BJT Design Sound better compare to IRFP240/9240

we have test it in Mosfet amp and in my opinion IRFP240/9240 is no go in mosfet amp

I and others have found the IRFP240/9240 combination to work very well.
I can only speak for my own designs but I have found them to work very well.
 
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This is just my theory...

Keep VAS simple, just a single tube...

Consider a triode connected 7788 (E810F)... load the anode with constant current source about 20 mA; will have a gain of approximately 50 with a reasonably low internal impedance (I do not have my note book here, but remember impedance as about 2 K Ohm, maybe lower).

Then AC (i.e. capacitor) couple it to your output stage.
 
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ECC88 is priority, I already have about 200 pieces.

Yes, that does change things!

Well, ECC88 has nice characteristics, so a simple common-cathode amplifier should get you what you want. I would estimate using a CCS anode load of 15mA, a -2V bias point, and 110V on the anode. However the output impedance of the stage might be reasonably high at about 2700 - 3000 Ohms. Maybe that is OK for your circuit, or maybe you might need a source follower between tube and output stage.

For info, if you have not seen them, Mr Wim de Haan shows some hybrids here: Wim's DIY Audio Projects
 
Yes, that does change things!

Well, ECC88 has nice characteristics, so a simple common-cathode amplifier should get you what you want. I would estimate using a CCS anode load of 15mA, a -2V bias point, and 110V on the anode. However the output impedance of the stage might be reasonably high at about 2700 - 3000 Ohms. Maybe that is OK for your circuit, or maybe you might need a source follower between tube and output stage.

For info, if you have not seen them, Mr Wim de Haan shows some hybrids here: Wim's DIY Audio Projects
Thank's for info,
Regards
 
I mean IRFP240/9240 are not really complementary devices, it sound horribile in mosfet amp...... BJT Design Sound better compare to IRFP240/9240

we have test it in Mosfet amp and in my opinion IRFP240/9240 is no go in mosfet amp

In what way do they sound bad? How does it show on measurements?

I'm not interested about best figure, can be better with BJT, but people just want tube/mosfet hibryd amplifier, and I don't want argue about that. Tube or SS also is not a question. Simple give people what they want.
Regards

I have always found tube/semiconductor amps kind of strange, or at least the reasons people wnat them. Hybrids are a sure way of getting the downside from both tubes and transistors at the same time......:confused:
 
In what way do they sound bad? How does it show on measurements?



I have always found tube/semiconductor amps kind of strange, or at least the reasons people wnat them. Hybrids are a sure way of getting the downside from both tubes and transistors at the same time......:confused:
People who want hybrid amplifier think that useing tubes and mosfets getting the best from both worlds at the same time.
 
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