The Phonoclone and VSPS PCB Help Desk

[rjm]

Rather than reading the help thread, my homepage gives a more concise overview. Theres even a FAQ on the PCB ordering page. I realise it doesnt answer all your questions though, so I'll address them below-

Q. Will it sound better than X?
-Ouch. Just so you know, asking a question like that basically paints the word NEWBIE on your forehead in dayglo pink. A. If X is a commercial unit costing less than $800 then yes, probably.

Q. How much will it cost?
-If you cant, in your head, price up a BOM for the circuit just by looking at the schematic (give-or-take a quick browse through digikey or partsconnexion) then you probably arent ready for this. A. Obviously it depends on on how much you pay for the parts, and this varies enormously from individual to individual. Audiophile components, a nice case, and a high quality transformer might easily price out to $200 or more, but it can built just as easily for under $100.

Q. Are there off the shelf power supplies?
A. Split, unregulated, linear external power supplies are rare. You'll see, though, once you start this, that it isnt worth the effort even looking: just get a transformer and some diodes instead, both of which are easily sourced. That's all that's needed, and the result will cost less and sound better.

I have been asked the "will I be able to do this?" question several times in the past. I have generally set the bar at the following: if you cant run through the design and construction of an unregulated +/- 15 V split power supply then its unlikely you'll be able to build a working phonoclone without a awful lot of help. I generally discourage people who fall in this category from proceeding. Too much of a nuisance for me, and too much frustration for them.

That sounds harsh but it isn't really. A couple of weekends of self-study at the library, and maybe one more kit project under their belt and these same people can come back and do it all without incident, to great satisfation of all concerned.

Richard

[robert1325]

Hi,

Thanks for your answer, and sorry for coming of like a newbie so much

I do understand the partslist provided on your webpage and have read the FAQ, I just wasn't sure ...

That split unregulated lineair PS looks Quite simple to learn and I'll probably be able to get some help on the PS part of the forum or on some other forum

Is that offer on the previous page really for the two phonoclone boards ( 20 dollar) ?

Robert

[rjm]

$20/pair. Yup. They are single sided and 1/4 Eurocard size like the VSPS, so they are a lot cheaper to manufacture than the BE version of the Phonoclone PCB. /R

[robert1325]

Hi, Thank you for your help, I think it's better for met to wait till I have a bit more experience.... I'm also wanting to add some kind of gain-stage /buffer in front of my amp , To much at once.

Thanks

Robert

[franksmith]

I just ordered some lme49710 from digi-key to test them in a dac and also in the phonoclone.

I'll keep you informed of the results.

[cromodora]

Originally posted by rjm

attached: Eagle brd and sch files for the phonoclone mini version 26i. I posted a similar board with RC filters and LM7x12s a while back. The most significant change is I updated my lbr files to have resistors and capacitors with wider pads and larger drill holes. In software jargon this version is RC2. Good to go, though I might have forgotton to dot an i somewhere.

/R

Looking at the board, wouldn't it be better if you can place the V-, V+, decoupling caps (C10,11,12,13) much closer to the IC legs?

[rjm]

Unfortuntaly unless I move to a double-sided board I did not find it practical to put them significantly closer. I uploaded the Eagle files so modifications can be made, however. Feel free to try moving things around and see what you can come up with. /R

[Nordic]

nothing prevents you from soldering a small decoupling cap, directly to chip pins....

[rjm]

... or attaching the 47-100 uF bypass themselves caps that way... they're small enough...

[rjm]

Finally got around to building the RC filtered version of the Phonoclone mini. I should have a chance to case it up this weekend and see what it sounds like.

For the record the power rails are as follows

1000uF/25V Nichicon FW
LM7x10 10V fixed regulator
100uF/25V Nichicon FW
10R
100uF/25V Rubycon ZA
(output stage OP27)
10R
100uF/25V Rubycon ZA
(input stage OP27)

The FW are the replacement for the Nichicon Muse at the local store where I buy stuff (Digit in Nipponbashi if you must know). The ZA are ultra-low impedance types that I was given over a year ago but never got around to using as I was reluctant to stick them directly on the output of the regulator for fear of instability. Isolated by the 10R resistance as they are here it should be the ideal application.

/R