Don't forget the body diode ...
A word of warning. MOSFET's have built in body diodes ...
I am seriously considering using emitter source to source n-channel JFET's for the balanced deal since JFET's are pretty good in both directions.
As far as using BJT's or MOSFET's I just don't know. Time to read some more in "The Art of Electronics".
BTW: the way to get a log response is to use more bits and a lookup table.
Petter
A word of warning. MOSFET's have built in body diodes ...
I am seriously considering using emitter source to source n-channel JFET's for the balanced deal since JFET's are pretty good in both directions.
As far as using BJT's or MOSFET's I just don't know. Time to read some more in "The Art of Electronics".
BTW: the way to get a log response is to use more bits and a lookup table.
Petter
hmm...
so, i was at a stereo shop w/some friends the other day, and i got to hear a Rowland Synergy preamp. i'm not sure if it was the latest version using the PGA2310 or the older CS3310 but i have to admit, the system sounded pretty decent, even though i am not a huge fan of B&W 802 speakers. the amps were Rowland as well. i did feel the system did not capture the subtle textures and shadings to the music that simpler systems do but i'm not sure how much of that is the electronics (e.g. preamp) and how much is the rest of the system. in any case i think the TI/Crystal volume chips are pretty darn good all things considered, i did not hear too much of the dynamic compression or glazing-over that i often hear from opamp ICs etc. better than i expected, but still not sure if it's good enough for Son of Dork. i'm sure Harry, HPotter, Jocko, and Jam would probably concur. 😛
so, i was at a stereo shop w/some friends the other day, and i got to hear a Rowland Synergy preamp. i'm not sure if it was the latest version using the PGA2310 or the older CS3310 but i have to admit, the system sounded pretty decent, even though i am not a huge fan of B&W 802 speakers. the amps were Rowland as well. i did feel the system did not capture the subtle textures and shadings to the music that simpler systems do but i'm not sure how much of that is the electronics (e.g. preamp) and how much is the rest of the system. in any case i think the TI/Crystal volume chips are pretty darn good all things considered, i did not hear too much of the dynamic compression or glazing-over that i often hear from opamp ICs etc. better than i expected, but still not sure if it's good enough for Son of Dork. i'm sure Harry, HPotter, Jocko, and Jam would probably concur. 😛
Possibly good enoug for Son of Dork
but only if used as shunting element, not pass element.
However, bearing in mind the lengts to which we are going to achieve great sound quality, I would suggest that electronic volume controls of the integrated ilk are not good enoug for Dork period.
My $.02
Petter
but only if used as shunting element, not pass element.
However, bearing in mind the lengts to which we are going to achieve great sound quality, I would suggest that electronic volume controls of the integrated ilk are not good enoug for Dork period.
My $.02
Petter
I know that the Coda 04R preamp uses the CS volume control chip and it sounds very, very good. A buddy of mine owns one and together we've put it up against some of the best on the market (not a pass unit yet....) and it usually comes out on top...
The upshot is, if it is designed well that chip really sounds good. I know the latest versions also only allow volume changes at the null point so they have eliminated the occasional clicking that was heard in the earlier versions...
This has been very interesting to follow. You guys are doing a great job!!!
Just a couple of thoughts,
The upshot is, if it is designed well that chip really sounds good. I know the latest versions also only allow volume changes at the null point so they have eliminated the occasional clicking that was heard in the earlier versions...
This has been very interesting to follow. You guys are doing a great job!!!
Just a couple of thoughts,
petter, i would have to agree with you, though w/o actually trying the circuits i really can not say for sure. but the PGA2310 does use a bipolar opamp as the output buffer, which many of us consider less than ideal. i do not think it can be used as a shunt either - the Maxim and Wolfson parts are passive and could be used that way though.
i'm glad we're setting the goals for Son of Dork very high. 🙂 a lot of people would kill for a preamp as good as a Coda or Rowland, and we are saying it is not good enough! i was never a fan of big high-end names though - audio is one thing, music is another. a lot of audiophile products get the former but miss the latter.
steve, i agree the Crystal/BB ICs can still sound very good when properly implemented. i am actually going to build a mini Son of Dork for my friend, a simple stereo preamp, that will probably use the PGA2310. for the full-fledged Son of Dork though i will probably go with a custom scheme using discrete components.
btw, the stereo version for my friend is called Bastard of Dork. catchy, eh?
i'm glad we're setting the goals for Son of Dork very high. 🙂 a lot of people would kill for a preamp as good as a Coda or Rowland, and we are saying it is not good enough! i was never a fan of big high-end names though - audio is one thing, music is another. a lot of audiophile products get the former but miss the latter.
steve, i agree the Crystal/BB ICs can still sound very good when properly implemented. i am actually going to build a mini Son of Dork for my friend, a simple stereo preamp, that will probably use the PGA2310. for the full-fledged Son of Dork though i will probably go with a custom scheme using discrete components.
btw, the stereo version for my friend is called Bastard of Dork. catchy, eh?
Look inside a "high-end" unit costing lots of money and love and behold what do you find?
Crap component quality.
As a Son of Dork participant, I cannot live with that.
BTW: If you must go with surface mount resistors, consider the new Vishay Bulk Metal foil units 🙂
Petter
Crap component quality.
As a Son of Dork participant, I cannot live with that.
BTW: If you must go with surface mount resistors, consider the new Vishay Bulk Metal foil units 🙂
Petter
yeah, i've seen the innards of a lot of "high-end" gear, and it is pretty appalling at times. i was at the shop listening to the Rowland w/my friend and i whispered in his ear "i can build something better than that for $500."
actually, i was sort of interested in these SMT resistors:
http://www.venkel.com/pdf/MELF_TFCR.pdf
i hear Vishay bulk foil can be quite bright-sounding. haven't heard tantalum before but they seem to be well-regarded.
actually, i was sort of interested in these SMT resistors:
http://www.venkel.com/pdf/MELF_TFCR.pdf
i hear Vishay bulk foil can be quite bright-sounding. haven't heard tantalum before but they seem to be well-regarded.
What happened to this one?
Some while ago now Audiofreak wrote:
What happened to this? I, along with many others I'm sure, would love to know more about Wayne's secret attenuator. I've been racking my brain for some while trying to guess at the topology but with little success. Any ideas would be greatly appreciated.
Ian.
Some while ago now Audiofreak wrote:
What happened to this? I, along with many others I'm sure, would love to know more about Wayne's secret attenuator. I've been racking my brain for some while trying to guess at the topology but with little success. Any ideas would be greatly appreciated.
Ian.
Audiofreak,
Please, how can I persuade you or indeed others to make a start on this? Given that Nelson has already thrown down the gauntlet, I'm a little suprised that nobdy has yet risen to the challenge.
Ian.
Please, how can I persuade you or indeed others to make a start on this? Given that Nelson has already thrown down the gauntlet, I'm a little suprised that nobdy has yet risen to the challenge.
Ian.
I've got to build some equipment for university 1st. I'm also trying to organise a mass MOSFET purchase which has gone on for months now with one problem after another but things are starting to look up on that front and I should see the FET's within 2 months (anyone out there that has expressed interest... it is going to happen soon ... sorry it's taken so long). Next chance I'll probably get to fiddle with Wayne's secret attenuator will be summer vaction which starts late November and runs for 3 months.
November
Oh dear, that seems a long way off. Unfortunately I can understand the problem with lack of time - seems to aflict most of us.
Come on guys (and gals) - there must be others with both time and the wherewithall to have a crack at this! I have a little time but not the wherewithall without some advice or hint as to how to begin.
Ian.
Oh dear, that seems a long way off. Unfortunately I can understand the problem with lack of time - seems to aflict most of us.
Come on guys (and gals) - there must be others with both time and the wherewithall to have a crack at this! I have a little time but not the wherewithall without some advice or hint as to how to begin.
Ian.
why don't you do it then Ian
I thought I already said: I am prepared to make the time and do any donkey work but I really don't know to start on this one. Believe me, I have been trying (and will continue to do so).
Prize? Do you mean I should offer one? I didn't think it took the lure of a prize to get folks going on this forum.
Ian.
I thought I already said: I am prepared to make the time and do any donkey work but I really don't know to start on this one. Believe me, I have been trying (and will continue to do so).
Prize? Do you mean I should offer one? I didn't think it took the lure of a prize to get folks going on this forum.
Ian.
i wrote that msg. before your other one was on the thread.
peter was referring to Nelson Pass's last prize to someone for figuring out some element of his super-symmetric circuit, i believe.
peter was referring to Nelson Pass's last prize to someone for figuring out some element of his super-symmetric circuit, i believe.
Yes, I was sugesting that somebody might try to win another prize from Nelson (if such would be offered of course). And I'm not saying it couldn't be Ian again.😉
Looks like Brian GT has made a lot of progress on this topic.
If he gets it ironed out and a group production, maybe it could become the attenuator/control section of Son of Dork?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=8611
If he gets it ironed out and a group production, maybe it could become the attenuator/control section of Son of Dork?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=8611
brian's got a nice prototype there, looks very cool. i especially like the VFD. unfortunately the switched relay scheme is not very practical for SoD (for 1dB steps over the required range i'd need dozens of them) but it is neat nevertheless.
i am still considering using CMOS switches as shunt elements. also looking into the Wolfson chip, but it doesn't seem anyone has tried it yet.
i am still considering using CMOS switches as shunt elements. also looking into the Wolfson chip, but it doesn't seem anyone has tried it yet.
dorkus said:
There is a whole lot of range with the volume control that I am working on. 256 steps of volume control to be exact. This should easily give the percision that you desire. The number of steps is 2^n where n is the number of relays that you have. Adding 2 more relays (10 total per channel) gives 1024 steps total. Here is the schematic:
As for chips, I tried the PGA2310 chip, and was not satisified with it at all.
--
Brian
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