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Old 21st August 2008, 09:38 AM   #491
Salas is offline Salas  Greece
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*Next step is I am gonna listen down to +/-10V PSUs. Will let you know soon. Maybe there is a sweeter spot. In that case, no input should exceed 3VRMS. We discard headroom by tuning down the PSUs.
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Old 21st August 2008, 09:49 AM   #492
EUVL is offline EUVL  Europe
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For your reference, I use 2x9V alkaline batteries, +/- rails, direct couple, 220uF Silmic across each battery, followed by 0.1u MKP1837 close to the JFETs. Cost less than 5 bucks.


Patrick
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Old 21st August 2008, 09:53 AM   #493
Tolu is offline Tolu  Germany
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Quote:
Originally posted by EUVL
For your reference, I use 2x9V alkaline batteries, +/- rails, direct couple, 220uF Silmic across each battery, followed by 0.1u MKP1837 close to the JFETs. Cost less than 5 bucks.


Patrick
Can you post the circuit and/or a photo?
How about the sound?
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Old 21st August 2008, 12:18 PM   #494
Salas is offline Salas  Greece
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Quote:
Originally posted by EUVL
For your reference, I use 2x9V alkaline batteries, +/- rails, direct couple, 220uF Silmic across each battery, followed by 0.1u MKP1837 close to the JFETs. Cost less than 5 bucks.


Patrick
Good choice for performance, I don't think that the batteries are going to last too long though. Not that practical for maintenance.

Anyway, I tested +/-12V, +/-11V, +/-10V. Used Paul Simon's Graceland and listened for best harmonic and vocal integration. Surely there is difference for voltage choice. +/-10V gives the creamiest sound but loses some dynamic contrast. +/- 11V regains enough contrast and loses enough coherence, and +/-12V is like before when with +/-15V. Mainly starker and less hypnotic. I prefer +/-10V and there it stays. Less Hi-Fi, more music.
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Old 21st August 2008, 12:54 PM   #495
Salas is offline Salas  Greece
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*Mind you that going lower than +/-10V isn't going the smoother and calmer. It isn't a trend. +/-9V sounds like +/-11V only a bit more pinched. +/-10V is the sweet spot where sibilance is more persuasively integrated, a fretless bass sounds more Pastorius trombone like, the brass shines edgeless, and the open guitar strums are cohesive.
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Old 21st August 2008, 12:56 PM   #496
AndrewT is offline AndrewT  Scotland
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interesting experiment.
I wonder if this is temperature related.
Higher voltages = higher dissipation = higher junction temps. At least in the upwards direction.
Did you re-check the offsets at each new voltage?
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regards Andrew T.
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Old 21st August 2008, 01:04 PM   #497
Salas is offline Salas  Greece
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Yes I did. Always under 1mV. The thing that I know is that the data sheets give Idss for 10V always. I don't know if it bears any relation.
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Old 21st August 2008, 03:56 PM   #498
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Salas,
Which tube preamp are you comparing to the B1? James
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Old 21st August 2008, 03:59 PM   #499
BFNY is offline BFNY  United States
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Quote:
Originally posted by salas
...But I don't like the tone of electrolytics as last caps. You can make it this and that and add this and patch that, but you will always listen to a JFET buffer, that will not change.
I would ask you to please try one more experiment. Add a quality bypass cap from the LM317/LM337 adjustment pin to ground.
Another 10uF tantalum would likely work well.

The reason why is explained here

http://www.tnt-audio.com/clinica/reg..._noise2_e.html

As you can see, it eliminates the peaking, and lowers the regulator output noise floor by over 20dB. It would be very interesting to see if you can hear a difference with this simple mod.
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Old 21st August 2008, 04:36 PM   #500
Salas is offline Salas  Greece
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Quote:
Originally posted by jimmyd53
Salas,
Which tube preamp are you comparing to the B1? James

That one.
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