The Phonoclone and VSPS PCB Help Desk

[cukkurullo]

Hi guys,

I have LT1086/4/5 regs for spares, I guess I can use the LT1086 insteas of the LM317 without any modification of the circuit, did anybody tried this?

Cheers,
Cukkurullo

[rjm]

They appear to be pin compatible with the LM317/337, so: yes.


*****


I was thinking again about parts count, regulation, and adding RC filter stages after the voltage regulator to attenuate high frequency noise.

If it worked it would be a cheap and simple way to improve the power supply. My gut feeling is that perhaps as it stands presently the design overly favors low impedance at the expense of increased noise. An RC filter network would redress that in a simple tradeoff of increased low-frequency output impedance for decreased high frequency noise levels. How much needs to be applied is an open question.

If someone wants to try it, put an RC filter consisting of 22 ohms and 100 uF at the power terminals of the input opamp and see if it makes a positive difference. Since very little noise is contributed from the second stage the benefit of applying the filter to the output stage is less obvious. An RCRC networks with the output opamp tapped from after the first RC and the input opamp powered from after the second RC stage is another option to consider if the initial trials are promising.
/rjm

[rdr]

Originally posted by rjm
They appear to be pin compatible with the LM317/337, so: yes.


*****


I was thinking again about parts count, regulation, and adding RC filter stages after the voltage regulator to attenuate high frequency noise.

If it worked it would be a cheap and simple way to improve the power supply. My gut feeling is that perhaps as it stands presently the design overly favors low impedance at the expense of increased noise. An RC filter network would redress that in a simple tradeoff of increased low-frequency output impedance for decreased high frequency noise levels. How much needs to be applied is an open question.

If someone wants to try it, put an RC filter consisting of 22 ohms and 100 uF at the power terminals of the input opamp and see if it makes a positive difference. Since very little noise is contributed from the second stage the benefit of applying the filter to the output stage is less obvious. An RCRC networks with the output opamp tapped from after the first RC and the input opamp powered from after the second RC stage is another option to consider if the initial trials are promising.
/rjm

That is a good thing. I would put that as near the op amp as possible and add the largest non-electrolytic cap you can fit to bypass the electrolytic to take care of higher frequency noise. As always, good ground wiring to a common point, avoiding loops, is advised.

[Ralph]

Starting building the Phonoclone myself I have some starter questions, I hope someone can comment.

If I want to build the Phonoclose as generic as possible (allowing for a great number of MC carts that is), what should I do? Is it sufficient to solder R1 (input loading) and R2 (gain) on sockets or should I also socket other parts?

Another question (forgive me if it's too newbie), where in the circuit can I change the Input Termination Capacitance? Isn't that something you need with a MC pre?

Last thing. I have a Denon DL-103 but also an AT MM cart. If I want to have both MM and MC support, should I also build a VSPS next to the Phonoclone for the MM cart?

Thank you,

Ralph

[rjm]

You can build a VSPS and Phonoclone in separate boxes, with a single external power supply that you plug into whichever unit you want to use. If you insist on the convenience of a MM/MC switch, its far easier to use a single conventional circuit with switchable loads and gains.

The Phonoclone isn't a jack-of-all-trades phono stage. Its MC only, and its not guarenteed to work with every MC cart out there.

If you want to keep the Phonoclone as versatile as possible, set R1 to zero, and either socket R2 or make it switchable over a range of values from 150 to 1500 ohms. (150, 330, 680 1500 suggested). Socket the input opamp so that you can use a OP27 or move to OP37 for really high gains)

There is no input load, so no input capacitance to worry about setting.

/R

[bruderse]

Hi folks,

I am totally new in this forum, and the reason why I joined is the phonoclone. My only experience in DIYHiFi is speakerbuilding for about 25 years, therefore I`m a little bit afraid if the skills aren`t to high for me. After only using digital equipment for some years, I am in the mood to reactivate my old analog gear to get some new kicks. I did not want to use my AV-amp with my old TD 125, SME 3009 and DL 103 so I got me an used integrated tube amp with line inputs only. I still have an old Ortofon MCA-76 step up, which sounded good to me on nearly any Integrated amp with a good MM-phonostage together with the DL 103. But since then nearly 30 years have passed and I doubt if it`s still ok in comparism to newer equipment.

There are two ways for me:

1. build a phonoclone, and leave the MCA-76 in the attic,
2. build a VSPS and use it with the MCA-76

any recommendations?

I nearly don`t know anything about active electronics, OP`s, transistors and so on. Until now my knowledge ends with L, C and R in passive crossovers. It would be very nice if you could tell me the "state of (phonclone)art" equipment-list for the use with the standard DL 103.

I think of using a 50 VA 2x12V torodial transformer for each channel, together housed in an diecast enclosure for a 3,5"USB harddrive. For the 2 phonostages I`d use a similar housing.

What Do you think about my plans?

After reading the complete postings here, but not remembering all of them ( and understanding max. half of them) I got the impression that this is a very constructive and helpful desk and allways on topic. The support from rjm seems to be 1.st class.
In other communities a thread couldn`t be as long as here without drifting anywhere.

Thanks for your help in advance.

bruderse

[rjm]

Since you have a DL103 already and express no particular plans to use MM cartridges, the Phonoclone would seem to me to be the better option.

- grab the .brd files from the homepage, and place an order with Olimex for a set of Phonoclone boards.

- compile a parts list and order what you need.

I suggest just going ahead with it and not worry too much about which brand of capacitor is currently considered to be the best one to use, etc.

If you have any questions though feel free to email or pm me.

/Richard

[esplanade]

Hi Richard,

I would like to order PCBs from Olimex for VSPS but am nervous that the re-order # RM270606 applies both to VSPS AND PhonoClone... is this correct? Any possible chance of confusion and getting the wrong parts? I realise that the order info includes a description as well as the # RM270606, but I just need some reassurance here...

many thanks.

[rjm]

I can confirm that's correct. There is usually multiple items on each order number, but Olimex files the phototools for all the items together under that number. It references both boards in this case, so you have to specify which and how many.

The order number doesnt tell them what your order will be, it just helps them find the previously filed datasets you are duplicating.

/R

P.S. Let us know how you make out with Olimex.

[Ralph]

P.S. Let us know how you make out with Olimex.

I ordered the board a couple of weeks ago. Communication and shipment was without hassle. The only thing that they really have to work out is the taxes (in the EU). Bulgaria is a EU member since Jan 1st so they have to charge taxes for the other EU members. Obviously that wasn't stated on their website. I got my boards as samples therefor.

PS: I got the re-order discount