The Phonoclone and VSPS PCB Help Desk

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#1,442
opa627 in vsps

I thought the opa627 was a drop-in replacement for the opa134. When I use it in the vsps, I hear music but very faintly. Like it drastically gut the gain somehow. Are there any mods I should do to make it work like the opa134. I didn't see anything in this thread that talked about this.

Thanks
 
#1,444
Phonoclone with batteries 🙂
 

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#1,446
Unfortunatelly, I had to use the LT1128 in the first section, because due to my Supex cartridge (SD-909, it has 0.2 mV & 2 Ohm) the phono unit was too noisy (wind noise) with the OP27 (R1 - 10 Ohm, R2 - 390 Ohm).
I will attache a picture from the "battery charger unit" - it is a another unit in separate box.

What kind of three more connections to the board, I will also attache some picture from that section what is in the phono board.
 
#1,450
RJM,

I am currently building Phonoclone & have a power supply question. Your config shows a dual 12V secondary trafo with bridge rectifier on each secondary & "middle sides" of bridges tied for common. I have a 12V-CT-12V transformer of appropriate size & was wondering if your config provides improved performance as compared to a single bridge rectifier across 12V sides with CT as common?
 
#1,451
If you only have a single center tapped winding then the only option is to use a single bridge rectifier. If you have two windings I recommend using two bridge rectifiers for two reasons : 1. it's simpler and more straightforward to connect and 2. it sounds better.

re. 2. it's not a difference that is worth buying a new transformer for.

/R
 
#1,452
RJM,

Finished the Phonoclone today and, after checking supply voltages and scoping noise level on outputs (flatline at 20 mv/div) hooked it up for a listen....very nice!!! Dead quiet with no hum or noise audible when preamp is set to highest listenable volume level.

The sound from my Denon 103R is smooth, spacious and precisely imaged and it's a huge improvement over my previous setup - PS Audio 2 MC headamp (late '70s vintage) and Phase Linear 4000 preamp. A bonus was that the PS audio headamp case was a perfect fit for the Phonoclone boards and the separately cased center-tapped EI transformer was a great match for the recommended trafo specs. So other than the PC boards and components, which were <$100, the only cost was time. A great DIY project...thank you!😎
 
#1,453
The latest addition to the fold. Built in an old DOD 1u rack case with new front panel from 3mm ali. Full dual mono with 2x 18-0-18 20VA traffos feeding LM317/37 pre-reg set to 15V. ICs OPA27 for regulator stages and BB OPA134 for RIAA. Caps in RIAA Styroflex polystyrene, rails Panasonic FC, Output Wima MKP10.

Need to dress leads and put lid on, put new cart on TT, and put TT on proper shelf as my floor is very live, but first impression very positive. Nice one R! 🙂
 

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#1,457
rjm said:
It would be interesting to compare the sound with and without the LM317 pre-reg to see which is better.
Click to expand...

I'll have to find some other traffos first, I doubt the X-Reg would like 25V up it! 😉

LM317s can be considered (in the context of the X-reg) as high frequency noise generators on the input. You may be better off without them.
Click to expand...

I couldn't see anything suspicious when I 'scoped it out on the bench,and I don't have a distortion meter, but it's certainly something I'll try when I have a bit more cash.
 
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