Vlad, it depends on where you live, I would think. Some places will be almost RF free. Other places, the RF is at annoying levels. This is why we do not strive for SUPER HIGH bandwidth with the Parasound products, we just do NOT know where the product will be used.
What is your bandwidth requirement? I see schottkies, but you may be using those for their lower forward drop primariliy.
Very sorry to hear. He was amazing for doing as much as he did for so long.
Actually the more I look at this the more I'd like to know what you are attempting to accomplish. At first I supposed that you wanted a differential input, but perhaps your first inverters just represent independent sources.
I was about to suggest to use a dual gang potmeter with one half used for R and the other for RV. I am wondering, what you are going to use this for?
I still can't figure out what it is supposed to do. Are there two independent sources to the left? Whatever it does do, I am sure that it could be done more precisely, unless somehow it is using the forward diode drops intentionally (as opposed to putting up with them as a nuisance).
When I first looked at it in the middle of the night I thought some sort of differential front end was intended, but this is not the way the circuit works.
bcarso,
I could be wrong about it but I think it has to do with another thread that Christophe has pertaining to an amplifier protection circuit. It is an external comparator taking a signal from the output and comparing it to the input signal. He can correct me if I am wrong but that must be part of the circuit that he has proposed in his own thread.
I could be wrong about it but I think it has to do with another thread that Christophe has pertaining to an amplifier protection circuit. It is an external comparator taking a signal from the output and comparing it to the input signal. He can correct me if I am wrong but that must be part of the circuit that he has proposed in his own thread.
Oh thanks! That would explain a lot! So the two input signals are independent in general, and he's looking for full wave rectification of each. And the reason the other person's suggestion wouldn't work is that the two signals can't be mixed linearly as it were, since in the pathological case of one being the inversion of the other they would cancel.
Thanks again. Now I have an objective, should I choose to pursue it 😀
Brad
First opamp has a diode in the feedback loop. Same for other input. Gain is -2. Now all you have to do is equal sum original input with -2X. The two products can go to the third opamp as either sum or difference.
Do you know what that thread is? I don't even know if the two inverters on the left signify two independent power amp outputs, or possibly taken together are the two outputs of a single-channel bridge-mode amp.
Actually, if it is something to set some limiter or overload protection, there are ways to make it better even with the one opamp and as well vary the gain with a single potentiometer. However, if it is something to prevent clipping distortion, and the power amp has unregulated rails, I could suggest some more efficacious approaches 🙂
Thanks a lot to all of you, for your interest to my previous question, and your answers. I had dig a little more, and it seem impossible to get anything precise with diodes, or to sum or to rectify: the offset vary following the levels. So i ended with 4 comparators, with two thresholds, no summation between the two sides. It is square, now. Two quad ICs (one more), but less parts around: only 2 resistors for the thresholds and an adjustable for the gap in the middle.
As habit, simple is beautiful. Thanks to you all, again.
As habit, simple is beautiful. Thanks to you all, again.
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Comparators hooked up with open-collector "wired-AND" outputs, as window discriminators, are a good way to go.
It's a bad season for audio. James Bongiorno also passed away, as well as Larry Klein, long-time editor of Stereo Review. And Brian Cheney from VMPS Loudspeakers.
jan
jan
In recent years, most of my design efforts have gone to phono stages, rather than line stages. I don't think that I will ever be able to improve the CTC Blowtorch in any way that would be useful, and certainly I would hate to go through all that effort and cost, once again. This is not true with phono stages, however.
Just this morning a received an E-mail from a CTC Blowtorch owner to UPGRADE his preamp with a phono stage. Last week, an associate virtually 'begged me' to start up Vendetta again. Apparently, the customers are out there, as vinyl has gained an upsurge.
What about the 'software'? Of course, there is the old vinyl that often is amazingly good sounding, better than 20-40 year old analog tape ever could be, if properly stored and not ruined by many plays on cheap equipment. There is also 'new vinyl' that is actually backlogged at the record pressing plants as it is so popular. Is it as good, or 'better' than the old vinyl? I don't know yet. It depends on the processing, sources of the music, i.e. CD, DSD, DXD, or whatever. With my allergy to digital, if any digital processing is used in the production of the vinyl recording, then all bets are off, and maybe another approach should be used, instead.
My biggest worry today, is using a digital delay for 'preview' rather than the old way of putting a reproduce head a few feet ahead to capture the signal and tell the control electronics in the disc cutter how much to widen the groove. Other methods could be used, and I hope that they are, but you never know without investigation.
Just this morning a received an E-mail from a CTC Blowtorch owner to UPGRADE his preamp with a phono stage. Last week, an associate virtually 'begged me' to start up Vendetta again. Apparently, the customers are out there, as vinyl has gained an upsurge.
What about the 'software'? Of course, there is the old vinyl that often is amazingly good sounding, better than 20-40 year old analog tape ever could be, if properly stored and not ruined by many plays on cheap equipment. There is also 'new vinyl' that is actually backlogged at the record pressing plants as it is so popular. Is it as good, or 'better' than the old vinyl? I don't know yet. It depends on the processing, sources of the music, i.e. CD, DSD, DXD, or whatever. With my allergy to digital, if any digital processing is used in the production of the vinyl recording, then all bets are off, and maybe another approach should be used, instead.
My biggest worry today, is using a digital delay for 'preview' rather than the old way of putting a reproduce head a few feet ahead to capture the signal and tell the control electronics in the disc cutter how much to widen the groove. Other methods could be used, and I hope that they are, but you never know without investigation.
Now, some would say: ' A phono stage is not a line stage' and imply that it is off topic, but it is not! Several CTC Blowtorch preamps have phono stages, that was offered initially at additional cost. It is the 'very best' way to have a Blowtorch, but many customers already had Vendetta Research SCP-2 phono stages or they were already totally digital, so few were built with the phono stage built in. Yet, it was a significant addition to the CTC Blowtorch, and I would not have it any other way.
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I've been purchasing some of the new vinyl and some of it is spectacular. And I have plenty of well-preserved old vinyl with which to compare. I suspect that the cutting is done in other ways, with a score so the operator knows in advance and doesn't rely on a hardware delay.
Of the latter (old vinyl), I was stunned the other evening by an old Nonesuch release, Calliope Festival. Now granted that Renaissance music is often of fairly limited dynamic range; but the fidelity and quiet surfaces were quite staggeringly good. I would suppose the record had been played once before, possibly never (the inner sleeve had that characteristic foldover of corners, which I always straighten out. But it was not in shrinkwrap.
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