Please Andrew, could you open new thread about links problem. This is clearly problem of the software used for this forum not users problem.
Sometime I don't understand you and your behavior.
You are too kind. Yes you could. I merely did the design and outsourced all the panel work to Modu. Apart from the front/rear panel it's just holes in the right place. I can't drill two holes in the right place let alone considerably more than that so I have to outsource it. Now designing an amp - that's hard!
100W amp: distortion 20k is 0.00036% (100W/8R). Wow! I need to study how you did the balanced input and arranged the feedback. Every textbook I have shows only single-ended IPS. I only have balanced source and so to build Toni's (astx) amp I first had to make a version of Douglas Self's low noise balanced to single-ended input board.
100W amp: distortion 20k is 0.00036% (100W/8R). Wow! I need to study how you did the balanced input and arranged the feedback. Every textbook I have shows only single-ended IPS. I only have balanced source and so to build Toni's (astx) amp I first had to make a version of Douglas Self's low noise balanced to single-ended input board.
It was discussed and posted in his "interview series"
I think it is also in his book.
Just four jFETs and a few resistors running off a reduced supply voltage.
Yes. it could be a tiny PCB attached to the input sockets.
A version of it is shown in Figure 26.4 p530
There is a small error in R7, I reckon it should be 2k625, rather than 2k63, keeping in mind the requirement for <<1% precision in input impedances.
But what is 5ohms between friends considering that is after the Buffer.
I think it is also in his book.
Just four jFETs and a few resistors running off a reduced supply voltage.
Yes. it could be a tiny PCB attached to the input sockets.
A version of it is shown in Figure 26.4 p530
There is a small error in R7, I reckon it should be 2k625, rather than 2k63, keeping in mind the requirement for <<1% precision in input impedances.
But what is 5ohms between friends considering that is after the Buffer.
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Note I said "don't mean".
Forgive my ignorance but it doesn't look (to me) as though what Damir has implemented in his 100W amp is a balanced to single-ended converter ahead of a single-ended design. Am I completely wrong?
I've gone the balanced to single-ended converter with my astx SA2014 build. That 'converter' could be placed ahead of any single-ended design. It has, however, always seemed circuitous to me and I have been most interested to learn more about IPS/VAS designs that accept balanced input directly.
(Let me know if that link doesn't take you directly to my thread's post 136 with pics of the assembled board.)
Forgive my ignorance but it doesn't look (to me) as though what Damir has implemented in his 100W amp is a balanced to single-ended converter ahead of a single-ended design. Am I completely wrong?
I've gone the balanced to single-ended converter with my astx SA2014 build. That 'converter' could be placed ahead of any single-ended design. It has, however, always seemed circuitous to me and I have been most interested to learn more about IPS/VAS designs that accept balanced input directly.
(Let me know if that link doesn't take you directly to my thread's post 136 with pics of the assembled board.)
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Your link took me to post136.
And your adaptor certainly has more components than R.Cordell's.
Cordell has a chapter discussing balanced design. but that is different from a balanced impedance connection, where the impedances of the connection are what needs to be balanced to achieve the interference rejection.
And your adaptor certainly has more components than R.Cordell's.
Cordell has a chapter discussing balanced design. but that is different from a balanced impedance connection, where the impedances of the connection are what needs to be balanced to achieve the interference rejection.
We are starting to drift away from Damir's amps but I found chapter 26.3 'lacking' and had asked in his thread that the next version of the book look at 'balanced designs' in more detail with at least one full example of how the feedback was integrated into the IPS.
Unless I am mistaken, Damir's 100W circuit is a 'true' balanced design. And the module for the 200W design isn't a balanced to single-ended converter.
Unless I am mistaken, Damir's 100W circuit is a 'true' balanced design. And the module for the 200W design isn't a balanced to single-ended converter.
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R. March and astx measured 200W version, I never measured as I don't have the tool yet. Just not enough time to do something about it, always trying something in amp design.
My CFA amp with balanced inputs does not use additional op amps converters(like instrumentation amplifier) but has built in discrete balanced inputs. Adding op amp balanced converter will increase distortion and I prefer to do that as the amp part.
Attached simulated CMRR dependent of the R76 value.
It's important to use 0.1% metal resistor in the input R18, R54, R2, R62.
Attachments
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comment --- to have a balanced Z input also requires the source and the cable/interface to be as well balanced. You wont find a twin pair cable wound to such precision (0.1%). Nor the bal output Z. So, some where there is needed a 'system' trim of R/C for best CMR. This is typically done at the Ips.
THx-RNMarsh
THx-RNMarsh
Thank you Richard for your comment.
For most domestic use one does not need balanced inputs and in this case there two possibility with this amp and the layout presented, pure CFA mode or VFA with higher impedance feedback network.
I still have two 200W CFA boards, look here: http://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-74.html#post4271136 , if somebody wants to build this 200W version I can offer those two boards for 30 EUR per board plus shipping.
Damir
Damir
It passed some time and I hope that some of you who bought the boards finished the amp. I appreciate very much your listening impression, measurement if done, the amp photos, suggestions, complains ...
I have some information from others, not many, and would like to hear more.
Thanks, Damir
I have some information from others, not many, and would like to hear more.
Thanks, Damir