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Using the AD844 as an I/V
Using the AD844 as an I/V
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Old 4th March 2017, 03:10 PM   #2211
sumotan is offline sumotan  Indonesia
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Totally agree with your findings Quan.
Be it linear or Shunt regs I myself find
that it's circuit specific. Like the Buf 03
that I've built tried shunts, Lt series
& lm 3 series , all of them sound different
but somehow the Lm 317/337 sounded
best so I embarked on building a
supply that I came across in Niam forums.
it uses 2 regs per rail with one acting as
a constant current source. Now this reg
really sounds very very good with Buf 03
If I dare say very organic not nasty sibilance
etc. That Kobuta regs that your using also
got me curious. Will try it out some time

Cheers & thks for sharing
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Old 4th March 2017, 09:24 PM   #2212
kazap is offline kazap  Australia
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Quote:
Originally Posted by sumotan View Post
......... Like the Buf 03
that I've built tried shunts, Lt series
& lm 3 series , all of them sound different
but somehow the Lm 317/337 sounded
best so I embarked on building a
supply that I came across in Niam forums.
it uses 2 regs per rail with one acting as
a constant current source. Now this reg
really sounds very very good with Buf 03
If I dare say very organic.......
That's interesting. With the BUF-03 burning loads of current in A-class, a constant current regulated supply kind of makes sense.

Please can you share the design and implementation details?
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Old 5th March 2017, 04:09 AM   #2213
sumotan is offline sumotan  Indonesia
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Hi Kazap
Pls visit acoustica.org.uk. look under 3pin regs.
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Old 29th December 2017, 12:20 AM   #2214
donovas is offline donovas  South Korea
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so i know this is 844 thread but can u parallel 861 like you do with 844?
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Old 29th December 2017, 02:41 AM   #2215
canvas is offline canvas  Taiwan
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Originally Posted by donovas View Post
so i know this is 844 thread but can u parallel 861 like you do with 844?
I've done this. 3 per channel. The bottom line is it didn't work as you expected. The high sounds like cut-off, but the mid was very smooth though.
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Old 29th December 2017, 04:30 AM   #2216
donovas is offline donovas  South Korea
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did the bass increase?
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Old 29th December 2017, 06:25 AM   #2217
Joe Rasmussen is offline Joe Rasmussen  Australia
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Quote:
Originally Posted by donovas View Post
so i know this is 844 thread but can u parallel 861 like you do with 844?
Haven't thought about that question, but the first that comes to mind is why would you do it? I can see why with the 844 since it runs low current in the transconductance stage, on the 861 you can simply just turn it up via resistor fitted to pin 1.

Others might have opinions on this? I would be interested to know if there is indeed an advantage.

Cheers, Joe
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Old 29th December 2017, 12:47 PM   #2218
canvas is offline canvas  Taiwan
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Originally Posted by donovas View Post
did the bass increase?

I'm afraid not. I switched back and like the tonal balance of single opa861. However, it's interesting to hear the difference.
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Old 29th December 2017, 12:51 PM   #2219
canvas is offline canvas  Taiwan
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Originally Posted by Joe Rasmussen View Post
Haven't thought about that question, but the first that comes to mind is why would you do it? I can see why with the 844 since it runs low current in the transconductance stage, on the 861 you can simply just turn it up via resistor fitted to pin 1.

Others might have opinions on this? I would be interested to know if there is indeed an advantage.

Cheers, Joe

Hi Joe,

I'm no expert on this. I heard people stacking AD844's for lowering the input impedance. I'm not sure if this also applies to OPA861. Maybe I didn't do it right, simply stacking 861's do affect the tonal balance to certain degree.

Poting
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Old 29th December 2017, 01:17 PM   #2220
Joe Rasmussen is offline Joe Rasmussen  Australia
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Quote:
Originally Posted by canvas View Post
Hi Joe,

I'm no expert on this. I heard people stacking AD844's for lowering the input impedance. I'm not sure if this also applies to OPA861. Maybe I didn't do it right, simply stacking 861's do affect the tonal balance to certain degree.

Poting
In the 844 you have two parts, you have the OTA front-end and in the 844 it runs at a fixed current and I estimate it might be only 2mA. By stacking the 844, the OTA has a lot more current, not just the other part, the buffer. In the 861 you can set it by a single resistor and easily run 3-4 times the current through the OTA part.

Mind you, the 861 is really meant for low -/+5V operation and the 844 can handle -/+15V and a bit more OK. So there are more variables there.

Cheers, Joe
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