has anyone tried the PGA2310 or Wolfson chip yet? - Page 2 - diyAudio
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Old 1st July 2002, 10:31 PM   #11
dorkus is offline dorkus  United States
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Default on the contrary...

it was not offensive at all. anyone who would be offended by your comments should really get a life.

sorry if i was sounding a little condescending myself. your webpage is most useful, and i did not mean to disparage your work - it is excellent. you seem to be very far along in your prototyping, which is more than i can say about my own projects.

i am not even particularly surprised that you preferred 5532 to OPA2134, as a lot of people don't like the sound of the 2134 (too euphonic?). it is good to keep an open mind as you say though, and i'm looking forward to your results with other devices. definitely put the AD825 and OPA8610/8620 on your list, they seem to be a couple of the "hot chips" around here lately. i'm actually about to try a OPA2604 in my SACD player, to be followed by a AD8620 if i get far enough along in my mods.
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Old 2nd July 2002, 01:53 AM   #12
rljones is offline rljones  United States
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I got some feedback from TI/BB. The buffer op amp is very similar to the OPA134. Maximum output current is 35 mA with an output impedance of 25 ohms.

Since many people use OPAx134 as output buffers, it would seem than an additional output buffer really isn't necessary with the PGA2310 when run with 12 to 15V rails.

dorkus, I too like the AD8610. I very happy with in my active crossover and phono stage.

And mhennessy, I very much like your site, it is very imformative. Thanks for sharing.

Regards, Robert
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Old 2nd July 2002, 02:39 PM   #13
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Hi dorkus,

Thanks for clarifying that - I wasn't sure what you meant, and I apologise for taking it the wrong way. As you can tell, I'm new here

I'll make a note of the opamps you recomend. I'm hoping that my listing skills (which are improving daily with my new speakers) will be up to the task! I'll report back my findings, but this is still some way off...

rljones - that's intersting information from TI/BB. I agree with what you say about the output buffer - I suppose that my reasons for adding one (as given on the webpage) are a bit spurious, but at the time, the PGA2310 was still a very new device...

Thanks to both of you for your positive feedback! When I've got some news on the preamp, I'll let you know...
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Old 2nd July 2002, 10:39 PM   #14
rljones is offline rljones  United States
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I forgot to add that the slew rate of the PGA2310 output buffer is 16 volts per microsecond per TI/BB. This is not so bad for a preamp: it should not slew limit with a 12.5 V output until after 200 kHz. Since most amps go full power by 2 V on the input, 2V would give a theoretical slew limit of 1.25 MHz.

These figures are based on the op amp slew calculator at http://hyperphysics.phy-astr.gsu.edu...ic/a741p3.html

Regards, Robert
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Old 2nd July 2002, 10:57 PM   #15
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Default Re: PGA2310 listening test

Quote:
Originally posted by rljones
So I removed essentially everything from the board, replaced the CS3310 with the PGA2310, cut a few traces, jumpered here and there, replaced the 7805 and 7905 with 12V versions, and added a 7805 for the digital voltage source.
I believe the PGA2311 has the same pinout as the CS3310 but it uses only +/- 5V, unlike the PGA 2310. Most of the specs are the same as the PGA2310, with the exception of max. input voltage(obviously) and a few others.
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Old 3rd July 2002, 01:23 PM   #16
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Yes. There's also a 4-channel version (the PGA4311)

Shame about the +/-5V analogue rails, else I would've used it for the surround channels (a seperate PCB on my preamp, using 2 PGA2310's). It might be useful for a low component-count all-balanced preamp...
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Old 3rd July 2002, 05:16 PM   #17
rljones is offline rljones  United States
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While the PGA2311 is a direct substitute for the CS3310 (discussed earlier in this thread), the PGA2310 runs at greater voltages (+/-15 V max) and can be daisy chained for multi-channel use via one of the pins (see data sheet). As I mentioned in my description, I'm using one PGA2310 per channel in a fully balanced preamp.

Regards, Robert
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Old 10th July 2002, 06:56 AM   #18
dorkus is offline dorkus  United States
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hi robert,

hmm, so i re-read your mods of the extra Synergy board you had lying around. i am actually building a preamp for my friend right now... we saw the latest Synergy at a dealer and he really liked it, in operation, looks, and sound. so i am building something like that for him. not Son of Dork, more like Bastard of Dork.

anyway how do you think your PGA2310-direct version sounds compared to the latest Rowland board version? i am thinking of this:

- balanced and unbalanced inputs
- unbalanced inputs go thru Jensen transformer to convert to balanced
- balanced signal go through Borbely JFET buffers (simple 2-transistor circuit, DC coupled)
- output of JFET buffer feeds PGA2310
- output of PGA2310 feeds another JFET buffer (same topology)

how does that sound to you? it is still DC coupled from input to output. if necessary it may need a DC servo at the output but i would like to avoid it as much as possible, hopefully some circuit tweaking will take care of it. the PGA2310 by itself should have enough gain right? the JFET gain is very close to unity.
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Old 10th July 2002, 12:58 PM   #19
BrianGT is offline BrianGT  United States
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What about using the OPA627 with the PGA2311? Would that be fine?

--
Bria
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Old 10th July 2002, 03:30 PM   #20
dorkus is offline dorkus  United States
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i've heard OPA627 is very finnicky and AD825 or AD8610 are preferrable. in any case i'd probably pick a simple Borbely JFET buffer for this application as i don't need any gain. why have another IC w/tons of feedback when i don't need it?
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