I use opto for at least six month by now and did not regret yet. They are controlling my DCB 1 buffer input. Not sure if they are better than step attenuator, but definitely not worth then Goldpoit or Khozmo. By the way, they do not need sophisticated PSU. 78xx or 317 should be good enough with CRC. I also use new 47 steps Goltpoint on my tube preamp. It sound very nice and much better than the original Alps.
Back to opto...
Opto setup takes time to match, but when you done, no regrets.
Sent from my iPhone using Tapatalk
Back to opto...
Opto setup takes time to match, but when you done, no regrets.
Sent from my iPhone using Tapatalk
I bought my optos matched from the Lightspeed inventor, George. So long as you solder them fast, so they don't heat up much, they should be perfect. An included balance pot allows you to trim any discrepancy. It was only about £30 as I remember, for the optoscoupled leds and optoresistors, the pcb and other bits.
Whilst I agree that a 78xx is quite sufficient, as it is only optically connected to the audio circuit, I had a spare positive Salas reg so figured why not? George certainly regards the supply as being important. Any high frequency fluctuation of the supply might potentially affect the leds and therefore the resistors.
It's the best I've heard. As good as a switched resistor array, with the advantage of smooth rotation, and therefore remote controllable. A perfect solution for transparency and practicality.
Whilst I agree that a 78xx is quite sufficient, as it is only optically connected to the audio circuit, I had a spare positive Salas reg so figured why not? George certainly regards the supply as being important. Any high frequency fluctuation of the supply might potentially affect the leds and therefore the resistors.
It's the best I've heard. As good as a switched resistor array, with the advantage of smooth rotation, and therefore remote controllable. A perfect solution for transparency and practicality.
My interpretation of the many posts by George is that PSU is not critical to Audio performance.
Hi Salas,
first of all thank you for starting this thread!
I am thinking about building another JFET phono preamp. I built the Pass Pearl 2 some time ago and really like it. The JFET sound is nice, that is why I would like to build your version of a JFET phono stage. Keeping track of all the post and details on this thread is rather hard and one gets confused, so could you please (re)-upload the latest version of your schematic and a PSU that you would recommend?
Thanks for your effort!
Best regards
poli
first of all thank you for starting this thread!
I am thinking about building another JFET phono preamp. I built the Pass Pearl 2 some time ago and really like it. The JFET sound is nice, that is why I would like to build your version of a JFET phono stage. Keeping track of all the post and details on this thread is rather hard and one gets confused, so could you please (re)-upload the latest version of your schematic and a PSU that you would recommend?
Thanks for your effort!
Best regards
poli
Rick, I have some possible suggestions for you re. your Lenco motor drive; I don't want to sidetrack this thread but PM me if you're interested.
Regards,
Andy
Post1 has a sch and three links to later developments.
Did you read any of them?
hi everyone.
after a long gestation and the incredible patience of Nick, finally my Simplistic is playing.
the construction, as you can see, is absolutely hobbistic but the satisfaction is great.
unfortunately the Dual 601 that you see in the picture creates some noise, a perceptible Hummm.
with my Lenco L75/s with the original old school cable and plug sound great.
after a long gestation and the incredible patience of Nick, finally my Simplistic is playing.
the construction, as you can see, is absolutely hobbistic but the satisfaction is great.
unfortunately the Dual 601 that you see in the picture creates some noise, a perceptible Hummm.
with my Lenco L75/s with the original old school cable and plug sound great.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Nice photos. I would try the sit the Dual to the other side of the transformers first. Also to make the white & blue cables that get to chassis the 0 side of the PSUs and the TT earth post very short and local to chassis. Using Yin-Young diodes between the white ones and the chassis if it makes a difference. No reason to go so far to the mains earth if the chassis is already connected to mains earth near the AC filter. Then to put the lid on also.
P.S. What design is the loudspeaker in the top photo background?
P.S. What design is the loudspeaker in the top photo background?
thanks Merlin 
.
I tried moving the TT but the problem persists.
connected or not connected to the ground lead, the situation does not change.
I already had a similar problem with another Dual but can not remember how I solved it.
maybe I sold the Dual
.
the speakers are the old model ITT type B530 M which they were replaced the original TW with the Advent "fried egg".
the next step will be replace the Md with the Grundig midrange.
p.s.: my amps are Braun A-301, Grundig Sv-40 and some more german amplifier.
the Lenco spinning Harvest by Neil Young, maybe the canadian first press, and the case.
.I tried moving the TT but the problem persists.
connected or not connected to the ground lead, the situation does not change.
I already had a similar problem with another Dual but can not remember how I solved it.
maybe I sold the Dual
.the speakers are the old model ITT type B530 M which they were replaced the original TW with the Advent "fried egg".
the next step will be replace the Md with the Grundig midrange.
p.s.: my amps are Braun A-301, Grundig Sv-40 and some more german amplifier.
the Lenco spinning Harvest by Neil Young, maybe the canadian first press, and the case.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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I already had a similar problem with another dual but can not remember how I solved it.
maybe I sold the Dual
Interesting vintage stuff there. The sound of the 70s H-Fi had a lot of European makes. From the 80s on they progressively abandoned that market.
sorry I did not understand.
my English is very poor and the Google Translate does not help much
all my TT have "standard" cartridge: Shure M75 or Shure V-15 III.
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P.S.
That cool looking "phonobox" had another interesting life in the past... although with some antiskating difficulties in this example
https://www.youtube.com/watch?v=zQwpzpsixQM
difference between with and without shunt?
I can only say that I like the sound.
After a few days I will try to reuse the standard phono of the amplifier to make judgments.
I stopped listening the "stereo" very long ago.
since then only I listen the music and try to listen to it well, to the best of my possibilities economic.
and the Simplistic allows this.
I can only say that I like the sound.
After a few days I will try to reuse the standard phono of the amplifier to make judgments.
I stopped listening the "stereo" very long ago.
since then only I listen the music and try to listen to it well, to the best of my possibilities economic.
and the Simplistic allows this.
The Dual may have oxides in contacts and wires also. Yet another critical area to investigate in vintage gear.
When the music satisfies you can't have gone wrong. Congratulations for your 100% handmade build.