Son of Dork: Attenuator - Page 3 - diyAudio
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Old 23rd June 2002, 08:13 PM   #21
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Default 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
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Old 8th July 2002, 07:12 PM   #22
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Default 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.
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Old 9th July 2002, 04:11 PM   #23
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Default 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
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Old 9th July 2002, 06:54 PM   #24
Apogee is offline Apogee  United States
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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,
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Old 9th July 2002, 07:21 PM   #25
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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?
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Old 9th July 2002, 08:58 PM   #26
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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
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Old 9th July 2002, 09:11 PM   #27
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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.
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Old 17th August 2002, 09:01 PM   #28
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Default What happened to this one?

Some while ago now Audiofreak wrote:
Quote:
I start holidays in 2 weeks, I'm going to put in some serious time on Wayne's secret attenuator which would be perfect for this and would fit between the 2 stages.
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.
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Old 18th August 2002, 01:37 AM   #29
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Ian,

Other things came up and I've put this on the back burner for the time being.
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Old 18th August 2002, 12:24 PM   #30
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Default 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.
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