USSPA Build thread

[fab]

The FFT software must display the 2hd harmonic polarity of phase. For example: -92 or 94 degrees for phase angle.
Fab

 

[fab]

It does not show visually on an FFT curve but in the report. Look in the upper left corner of my report screen.
The method I use to visually see the phase of the distortion harmonics consists in an analog distortion analyser to superpose the distortion signal (containing all harmonics) with the source signal. Of course you need to have only low harmonics dominant to really see something...
But really the FFT software is all you need. On the report you see that H2 is -91 degrees thus negative.

Fab

 

[AnthonyA]

Thank you Fab

I don't think the oswon oscilloscope have that... I'll try it when the supply is here,

Still using usspa on my main system. It's getting better as it age. It's now warmer with texture, bloom and weight. So... Whoever made it... Just keep it on 24x7.. And enjoy

 

[fab]

Hi AnthonyA
I had measured my USSPA-1 and the H2 is positive (+91 deg) with no R19/R20 installed.
Probably most of the USSPA preamp units built have positive phase H2 (with no adjustment) because maybe 2SK170 jfet has more transconductance than 2SJ74 and assuming IDSS is reasonably matched....

Thanks for the feedback on sound after after all this time

Fab

 

[AnthonyA]

Fab.

Finally one of the supply arrived. Will assemble within this couple of weeks

 

[nounouchet]

Hi,
I made a USSPA1 several months ago. It works with an LDR volume control driven by an arduino nano.
It's powered by a Salas DCSTB PSU.
It sounds fantastic !
nounouchet
https://www.diyaudio.com/forums/attachment.php?attachmentid=816886&stc=1&d=1581609446

 

[fab]

Hi AnthonyA
Where do you find this voltage regulator?
Fab

 

[fab]

Hi Nounouchet
Thanks for the feedback but the link to your setup seems invalid...

Fab

 

[Harry3]

AliExpress has different types of power supply boards e.g.

Buy Products Online from China Wholesalers at Aliexpress.com

 

[AnthonyA]

LT1963+LT3015 Ultra-low Noise Positive & Negative Linear Regulator Power Supply | eBay

 

[fab]

Thanks Harry3 and AnthonyA
Fab

 

[nounouchet]

Hi Nounouchet
Thanks for the feedback but the link to your setup seems invalid...

Fab

The inside:

 

[AnthonyA]

3 dollars 2nd hand psu box. Lolol

Didn't turn out too bad. Grin

 

[fab]

Thanks for posting you build picture Nounouchet, nice implementation!

It is a quite cheap enclosure AnthonyA!

Fab

 

[AnthonyA]

Fab ur items arrived
. Together with ecw and studer 900 supply



Quite value for money studer 900... As it includes nover cap

 

[nounouchet]

Quite value for money studer 900... As it includes nover cap

You think nover caps are good capacitors?!?
Impossible to get his specs.
I change them.

nounouchet

 

[AnthonyA]

Tried them before ..ain't bad. Warn British sound

 

[AnthonyA]

Assembled. Boy this kit is pretty easy assembled in less an hour. Bad point is it's made up of the same 2 half. So not CT transformer accepted.

Wait another day to test the power supply for usspa

VS lt 1963/3015

 

[AnthonyA]

Nounouchet.

You right .cap is bad . doesn't want to maintain voltage .thanks

 

[AnthonyA]

It's being warmed up will assemble fully when got time. No problem with biasing and such. So preamp is working for sure.

Studer900.. I might not recommend. I kept it on standby for few days. The voltage plus and minus varies 0.2 0.3v one side higher than other will be problem with DC coupled . I have no idea why. It was ok first 2 days. Lt 1963a /lt3015 is always rock stable at most 0.02v over time. I had better luck with amb Sigma.. And sounds pretty good.. But that's not yet long term use.. Pinnocchio loves them should be good.