You might be right, but I always use my own power amps, and it doesn't seem to make much difference. This is a potential problem with SOME power amps, I might think them, poorly designed in some way, but the marketplace is vast, and lower Z will keep you out of trouble more, than medium Z. Please note the substantial output buffer designed into the Parasound JC-2 preamp, by the same designers. We like to make universal products, 'designer proof' in that they will drive just about anything.
Thanks John for your answers and contribution - learnt a lot including information from your friends
. Are you still building this model or stopped? I see news that Vendetta is coming out with new version?kannan
We don't build the BLOWTORCH anymore as it was too expensive for US to build it. There just was not any money in it, for the time and effort to produce it. For example, we would sell the product direct to customers with a lifetime warranty. I have one here that was blown up by an erratic input pulse (both channels blown the same way) that I had to repair for nothing. We made this decision, years ago, when Bob Crump, the major force in this effort, was still alive. Virtually everything: cases, volume controls, etc had doubled in price since we first used them, years before.
As far as the Vendetta phono stage is concerned, we have developed it to advance prototype level, but we decided not to go forward until we found a customer base to support it.
As far as the Vendetta phono stage is concerned, we have developed it to advance prototype level, but we decided not to go forward until we found a customer base to support it.
It’s good to see that this thread is up and running again.
This is a small contribution to the discussion about volume control and also about output Z.
PMA (sadly and without any technical reason is put in the sin bin) asked about the CH volume control. It was also a discussion about the output impedance on the BT amp and that the gain would change by the load.
As you can see of the attached schematic this is a BT similar amp with a cascode on the input stage (so the PSRR should be a bit better) it also has a buffer on the output stage. Putting a buffer on the original output stage will make the gain (more or less) independent of the final load (the input of a power amp)
By putting a buffer on the output stage and varying the gain setting R’s in the original BT we are getting a CH like volume control (VGT).
In the attached schematic these resistors are R13 and R21. Please note that these resistors need a very close matching, so a stepped attenuator is needed.
Cheers
This is a small contribution to the discussion about volume control and also about output Z.
PMA (sadly and without any technical reason is put in the sin bin) asked about the CH volume control. It was also a discussion about the output impedance on the BT amp and that the gain would change by the load.
As you can see of the attached schematic this is a BT similar amp with a cascode on the input stage (so the PSRR should be a bit better) it also has a buffer on the output stage. Putting a buffer on the original output stage will make the gain (more or less) independent of the final load (the input of a power amp)
By putting a buffer on the output stage and varying the gain setting R’s in the original BT we are getting a CH like volume control (VGT).
In the attached schematic these resistors are R13 and R21. Please note that these resistors need a very close matching, so a stepped attenuator is needed.
Cheers
But Stinius, you have used twice as many parts in the audio path and have primarily copied what Charles Hansen would design. I wanted to be different. I had a shielded case and a superior power supply, why did I have to cascode a cascode?
If you want a preamp similar to this, just look at the Parasound JC-2. we add even more parts in the path by double cascoding, and adding an output buffer. The JC-2 is designed by the same people who designed the CTC BLOWTORCH. Yet we do not consider it our best design, even though it is close. Cheaper too!
If you want a preamp similar to this, just look at the Parasound JC-2. we add even more parts in the path by double cascoding, and adding an output buffer. The JC-2 is designed by the same people who designed the CTC BLOWTORCH. Yet we do not consider it our best design, even though it is close. Cheaper too!
The proof of the pudding is by eating.
This nice schematic will be meaningful to me once some one will build it and there will be listening reports.
Meanwhile, I'm following John's advise and I bend my mind into tubes.
John
It was not meant as a copy of Charles line amp, but as a circuit for discussion, based on a buffered OPS and VGT volume control
Joshoua
everything. (BH)(SA)
Cheers
It should have a separate thread, because it is too close to Charles' original design, and deviates from the direction that the Blowtorch took. However, it is a good approach, and I will be using a similar approach in 2 future designs, if they go forward. In my case, it is because the requirements necessitated an output buffer, and it could not be avoided. Still, the single load on the drive stage is compromised by going through the voltage sources. I recommend changing it.
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Agree, but the circuit I posted was meant as an example to explain and discuss the technical approach, it was not meant to be a final circuit.
Cheers
Wow, thanks dude, I feel so flattered that you officially leave the forum to me and the other guys who syn08 is so happy to call them "my friends."
Take care, and don't be a stranger now.
you don't get it, do you? I just read in the cable forum that the original Edison drum sounds better than a CD, so there's nothing surprising here...
stinius:
if this is not the right place, your schematic and subsequent discussion would be welcome in this thread i think:
http://www.diyaudio.com/forums/solid-state/104577-ayres-equilock-what.html
btw, you are likely correct about the mirrors.
mlloyd1
if this is not the right place, your schematic and subsequent discussion would be welcome in this thread i think:
http://www.diyaudio.com/forums/solid-state/104577-ayres-equilock-what.html
btw, you are likely correct about the mirrors.
mlloyd1
I agree, and am reconsidering ignore lists. Start a thread and talk about real circuit issues. You won't get all the free hits that JC generates, but I'm sure the net value will increase.
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