Based on the web site it looks like a fine audiophile social club. Seems like members are well equipped with high end commercial gear and enjoy gourmet food and spirits. I am sure it is a fine group.
The diyaudio group is more oriented to DIYAUDIO. We enjoy a great meet in a more of an industrial setting. A bit more like burning amp. Both share a love of great audio. There could be some intersection in the two groups but I think unlikely.
The diyaudio group is more oriented to DIYAUDIO. We enjoy a great meet in a more of an industrial setting. A bit more like burning amp. Both share a love of great audio. There could be some intersection in the two groups but I think unlikely.
Well, membership is by invitation only. I think I have heard of them via an acquaintance quite some time ago.
Hi Rick,
That is a really good prototyping setup you have there. I'll bet is solves a number of problems.
I would expect On-Semi parts to be robust. Texas Instruments used to make horrible transistors. Cheaply made with very thin leads. Basically junk. You went to Motorola or Fairchild if you wanted something that would last.
-Chris
That is a really good prototyping setup you have there. I'll bet is solves a number of problems.
I would expect On-Semi parts to be robust. Texas Instruments used to make horrible transistors. Cheaply made with very thin leads. Basically junk. You went to Motorola or Fairchild if you wanted something that would last.
I didn't know either. Might not be my cuppa ...
-Chris
wall of sound
There is your wall of sound, must be pink floyd fans.
I'll take the set in the middle please.
Powered up DH-220C last night, using some dual die lateral fets, I had on hand, hoary, it works, rise/fall was around 350ns, half of what the bjt OPS design does. Bob C. says that he runs his at 200mA per device, so that is 400mA through those devices, that big heatsink gets warm. Adding the two 0.22 ohm resistors in series with the drains allows you to measure the bias current.
One thing I noticed, the DH-220C bias is steady, from power up to warmed up. With the bjt ops design, the bias goes all over the place, +/100%, until it stabilizes, an hour later with a big HS. This is with the sensor bjt mounted onto one of the op devices as recommended.
There is your wall of sound, must be pink floyd fans.
I'll take the set in the middle please.
Powered up DH-220C last night, using some dual die lateral fets, I had on hand, hoary, it works, rise/fall was around 350ns, half of what the bjt OPS design does. Bob C. says that he runs his at 200mA per device, so that is 400mA through those devices, that big heatsink gets warm. Adding the two 0.22 ohm resistors in series with the drains allows you to measure the bias current.
One thing I noticed, the DH-220C bias is steady, from power up to warmed up. With the bjt ops design, the bias goes all over the place, +/100%, until it stabilizes, an hour later with a big HS. This is with the sensor bjt mounted onto one of the op devices as recommended.
Attachments
How fast does one need? What was the original DH-220, I wonder?
I measure it flat into the MHz. A 100Khz square wave looks perfect.
The limitation is written in the book, the RC time constant at the gates, there is a 220 and a 330 ohm in series with the gate capacitance, iirc ~900pf for the P-channel device. The series R's are to inhibit oscillations.
The drivers are running at 20mA, with a +/-65V supply, I had to put a heatsink on them. Bob spec'd it for 16mA, so it is close.
I measure it flat into the MHz. A 100Khz square wave looks perfect.
The limitation is written in the book, the RC time constant at the gates, there is a 220 and a 330 ohm in series with the gate capacitance, iirc ~900pf for the P-channel device. The series R's are to inhibit oscillations.
The drivers are running at 20mA, with a +/-65V supply, I had to put a heatsink on them. Bob spec'd it for 16mA, so it is close.
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I wasn't sure where the issue was, and I did indicate that the slew rate you have is probably good enough for audio. It is nice not to have too much phase shift in the audio band, and that requires a higher frequency response as you have. You didn't state what the gate charge/capacitance was like, and I'm not going to dive into a book over a casual post.
Boy, are you being picky today.
Yes, the driver need a heat sink. You might even be further ahead to use a TO-126 part with heat sink instead. That's up to you. The originals already have a heat sink anyway. I always found these amps to be nice in their way, and reliable too.
-Chris
Boy, are you being picky today.
Yes, the driver need a heat sink. You might even be further ahead to use a TO-126 part with heat sink instead. That's up to you. The originals already have a heat sink anyway. I always found these amps to be nice in their way, and reliable too.
-Chris
Electronics is picky work 
One wrong pick and smoke.
You say a way to make it faster but fail to say why you would need it faster.
You are funny, "probably good enough for audio"
Can you name an amp that you have measured or they have spec'd, being faster? not that it matters a whole lot, but it is a *******(pi$$ing) contest. <--- AI at work
What do you think the rise time is for a tube amp, you are into 10's of uS.
I'll ask ASTX (Tony), what his CFA amp does, out of curiosity.
merlin, your web site ? Welcome to MASSDUMP!
One wrong pick and smoke.You say a way to make it faster but fail to say why you would need it faster.
You are funny, "probably good enough for audio"
Can you name an amp that you have measured or they have spec'd, being faster? not that it matters a whole lot, but it is a *******(pi$$ing) contest. <--- AI at work
What do you think the rise time is for a tube amp, you are into 10's of uS.
I'll ask ASTX (Tony), what his CFA amp does, out of curiosity.
merlin, your web site ? Welcome to MASSDUMP!
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I'm ambidextrous - SS and Tubes (and so is Anatech). Most of my stock of finished and half finished projects are SS but I'm a big fan of tubes and most of my next round of half finished projects will be tube based. If I attend I can bring a 6AS7 SET amplifier (somebody else will have to bring sensitive speakers). This was my first attempt at tubes and would love to chat with another tube fan. And the power transformer gets hot enough we can use it as a back-up BBQ. I'm working on another project, using SV811 triodes but I don't think it will be up and running until late summer.
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