I design with 8 leg devices also, but they cannot match paralleled jfets or selected bipolar transistors. My low noise designs for example are about 2.5 times or 8dB LOWER than Scotts AD897 at its best. That is just a fact of life. I do use a an IC roughly as quiet as an 897 and with all the added circuitry to make it work as an amplifier, I get more than 1.5nV/rt Hz, because of the necessary feedback resistor (in my case, 50 ohms). The problem is that the IC CANNOT properly drive the feedback resistors (they are in series) and maintain a lowish gain of 30dB or so, because the output stage of the IC is so compromised in order to save operating current. You just have to put up with these tradeoffs when using an IC. '-)
Then I must do something wrong when I get 220 pV/rt Hz from 10 ADA4898-2.
(really 200 pV) without selection. Just as they come from the tape.
And I could go further, when soldering wasn't so boring.
And it would work with AD797 just as well, but the 4898 is cheaper.
(really 200 pV) without selection. Just as they come from the tape.
And I could go further, when soldering wasn't so boring.
And it would work with AD797 just as well, but the 4898 is cheaper.
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Don't lose sight of the fact that H&H's most extreme examples are for a ribbon mic at Rs of 20 mOhms and devices running at 100mA Ic, the circuits in fact as is would not be the lowest noise solution for most MC preamps.
As an aside, ignoring the noise of the air load on the ribbon could make this exercise about on the level of looking at the noise of the motor assembly on a cartridge and ignoring the surface noise of the vinyl. I never found a lot of information but IME ribbon mics even with good transformers did not have world class noise floors. I might be wrong and invite any real data on this.
A long time ago someone demoed for us a preamp for a classic RCA ribbon (transformer removed) using only an NPN/PNP pair of the now unobtainium RHOM devices. The noise floor was not audible.
And their probably cheaper than genuine Toshiba FET's, MUCH cheaper than the old tophat ones.
I haven't. My sunday best cartridge is 6 Ohms DCR so that pretty much sets the limit on how far it's worth me going. I did find out about the Nakamichi ribbon cartridges recently which are bonkers low enough DCR and low enough output to justify heroic low noise amplifiers, but I'm unlikely to ever own one of those. I also have the mildly silly Denon DL-304 with an air coil which is low output and high DCR. If that can be made so noise is well below the vinyl noise floor then it proves the (ultimate) fruitlessness of aiming for mad low number.
AD524 topology with Zetex devices I think will hold me for quite a long time. And annoy those who think that instrumentation amps are not good enough for audio 🙂
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RIP Charles Hansen
Oh man, this is just sad, he is gone too soon...I really enjoyed working with him when he was developing the Pono DA. Another luminary gone...
Howie
Oh man, this is just sad, he is gone too soon...I really enjoyed working with him when he was developing the Pono DA. Another luminary gone...
Howie
And if, instead of saddening you with the death of an audio designer, did you begin by stopping here this endless "J.C. bashing" which smells of jealousy ?
The living *need* more respect and sympathy than the dead and will be regretted when their turn comes.
The living *need* more respect and sympathy than the dead and will be regretted when their turn comes.
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I am assuming you are addressing this post to the group in general, not me in particular, since I have never "bashed" JC. I think your perception of the import of some comments here made towards JC is too severe. John Curl has proved himself capable of defending himself, so I do not fear for him. He has peers here who certainly have the right to call JC on points they disagree with, although they may do it in a way which is less than even-tempered.
When I read the posts in this group (and others including groups I own and moderate) I ignore the emotional content much as if I was working with a customer who was upset something didn't work. I try to understand the underlying factual basis and reject the invective. It is always a good idea to stick to facts and not acknowledge posts by others who are less discrete.
Cheers!
Howie
No it often has a hint of BS and is that smell some of us object to, so as it is open debate and not a sycophant worshipping site we disagree, there is nothing personal in it. If you bother to read this thread from earlier days you will find its like a roundabout, the same themes and discussions come around ad nausea and we still all dive in.😀 That's part of the fun of it... Look how often BQP's come up... Or matched FET's or...
Respect and disagreement are not mutually exclusive.
Thank you Tournesol for your insight regarding my situation. I've been putting up with it here for more than 10 years and even longer from other websites. I would rather contribute more, but it has been difficult.
Now, Charley Hansen was the closest designer to my philosophy of design in the audio business, and I will miss him. We were actually competitors, but we shared a bit with each other, especially where we were not in direct competition. Charley was the first to actually recommend this website to me, back about 14 years ago, but he could not stay here because he got even more criticism than me and he just could not resist fighting back in force, and this activated the moderators and he would get penalized. Regarding this thread, he commented to me that it got more and more difficult to find over the years. First it was up front, then it was moved to somewhere else, and then finally relegated to 'the lounge' in order to dilute it further, no matter how many hits it had gotten over the years. Charley would not put up with this, but I decided to hang on.
When it came to parts both active and passive, Charley and I used virtually the same parts in our competitive designs, because we found them to work the best, and we learned this independently of each other, decades before.
We also used similar circuits and even partially copied each other over the decades. I have admitted that the CTC Blowtorch circuit is derived from Charley's power amp design without the output stage. I was too 'chicken' to be this adventurous initially, and Charley led the pack with the complementary differential folded cascode which he used in a commercial amp decades ago. By the way, it is a 'perfect' open loop type circuit topology.
I never learned all of Charley's design 'secrets' which is unfortunate, but even if I did, they would be 'laughed at' here, because they were normally derived from open listening, just like I do.
Well RIP Charley, I will certainly miss you.
Now, Charley Hansen was the closest designer to my philosophy of design in the audio business, and I will miss him. We were actually competitors, but we shared a bit with each other, especially where we were not in direct competition. Charley was the first to actually recommend this website to me, back about 14 years ago, but he could not stay here because he got even more criticism than me and he just could not resist fighting back in force, and this activated the moderators and he would get penalized. Regarding this thread, he commented to me that it got more and more difficult to find over the years. First it was up front, then it was moved to somewhere else, and then finally relegated to 'the lounge' in order to dilute it further, no matter how many hits it had gotten over the years. Charley would not put up with this, but I decided to hang on.
When it came to parts both active and passive, Charley and I used virtually the same parts in our competitive designs, because we found them to work the best, and we learned this independently of each other, decades before.
We also used similar circuits and even partially copied each other over the decades. I have admitted that the CTC Blowtorch circuit is derived from Charley's power amp design without the output stage. I was too 'chicken' to be this adventurous initially, and Charley led the pack with the complementary differential folded cascode which he used in a commercial amp decades ago. By the way, it is a 'perfect' open loop type circuit topology.
I never learned all of Charley's design 'secrets' which is unfortunate, but even if I did, they would be 'laughed at' here, because they were normally derived from open listening, just like I do.
Well RIP Charley, I will certainly miss you.
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