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Old 27th April 2011, 05:37 AM   #1531
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Richard Murdey
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From what I can tell from the photo you posted earlier, you have Q1 oriented backwards on both boards. the heavier, longer line of the part online on the board indicated the back side of the transistor, the shorter tapered side indicates the front. The front of the transistor can be identified easily as it's the side with the lettering on it.
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Last edited by rjm; 27th April 2011 at 05:40 AM.
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Old 27th April 2011, 10:41 PM   #1532
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Hi RJM,
Im going to buy the VSPS300 boards this weekend but I do have one question before i pull the trigger. I have this case and will be using it for the project. My question is, how important is it to build the power supply stage apart from the rest of the boards? Will I be wasting my time in using this case? Here is the link to the transformer I will be using. As you can see the internal depth of the case is 320mm and the 2 VSPS300 boards next to each other will be ~200mm. The OD of the transformer is 87mm. So thats about 33mm between the edge of the transformer to the vsps board. What do you think ?
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Old 27th April 2011, 11:41 PM   #1533
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The case and transformer you picked look good. When putting the transformer in the same case with the boards you just have to be a little careful about a couple of things.

1) The VSPS chassis in now earthed, which can in rare cases cause complications with ground loops.

2) The VSPS300 circuit is not especially susceptible to magnetic fields, and a toroid is anyway fairly "quiet", but the magnets in some unshielded MM/MI cartridges (hey Grado, I'm staring in your direction) can be adversely affected by a power transformer sitting close by. With a separate power supply it7s easier to move the transformer well away from the TT to avoid this.

Not really a caution, but it's worth noting that a separate power supply can be "reused" for different projects: you can unplug the VSPS and plug in a Phonoclone3, headphone amp, or small gainclone (for computer speakers or something).

Those are the reasons I recommend a separate power supply. 99% of the time a one-box built will work out fine.
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Last edited by rjm; 27th April 2011 at 11:49 PM.
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Old 30th April 2011, 04:10 PM   #1534
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Quote:
Originally Posted by rjm View Post
From what I can tell from the photo you posted earlier, you have Q1 oriented backwards on both boards. the heavier, longer line of the part online on the board indicated the back side of the transistor, the shorter tapered side indicates the front. The front of the transistor can be identified easily as it's the side with the lettering on it.
Thanks Richard, it wasn't the orientation, it was that I installed the two bd135's together on one board and the two bd136's on the other... I forgot the measure twice, cut once rule. I had paired them when I took them out of the bag, but obviously didn't pair them well enough. I also damaged one board's base pad (the Q1) while removing the two wrongly placed parts and had to jumper Q1's base to the leg of R22 that is closest to the base to get the board working again (as per your recommendation).

Thanks to all who helped, it is much appreciated.
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Old 31st May 2011, 06:49 PM   #1535
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I recently built a VSPS300 using the recommended BOM parts and there's a slight 60Hz hum in both channels both with a MM cart connected and with the inputs shorted to ground. I've checked and doubled checked all ground connections by resistance when off and then voltage when on. The voltage rails hold steady at approx +/- 9.25V. All parts are in the correct orientation. I'm completely clueless as to where it is coming from.
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Old 31st May 2011, 07:54 PM   #1536
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RJM,

I am building a protoboard version of the Xreg to power the OPA2134-based analog signal processor for my Linkwitz Orion+ speakers, which calls for about 300ma at +/-12V. In the schematic for Xreg you show one NE5532 dual opamp. In the Phonoclone 3 I built you called for a pair of OPA27. I have the choice of using either a pair of OPA27 or one OPA2134...any preference you would recommend?
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Old 1st June 2011, 08:47 AM   #1537
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Emoose:

9V rails tells you everything is working fine.
60 Hz hum with the inputs shorted tells you that the noise pickup is happening inside the case but independent of the input state.

Make sure the internal wiring is tidy: IN+ and IN- are twisted together and kept well separate from OUT+ and OUT-, and V++,COM and V-- are twisted together and well away from the input and output wires.

The VSPS300 should be in a metal case, COM connects to the chassis.

If the transformer shares the case there is a potential for hum pickup. Try lifting the "earth" connection in the power supply.

Kevin,

I use the OP27 in the Phonoclone 3 / VSPS300 for four reasons,

- its the same op amp used in the amp circuit: simpler stock list of parts
- the layout happened to be more convenient
- ultimately the performance should be better due to the lack of crosstalk
- the Xreg circuit is complementary to the phonoclone circuitry, same gain, so it was fitting to use the same op amp.

I don't have a recommendation for you, it's whatever you find more convenient.
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Old 6th June 2011, 07:30 PM   #1538
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Thanks RJM, looks like having the inputs and outputs too close to each other was the cause of the issue. Now it's nearly silent even while not in a case for the time being.
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Old 27th June 2011, 02:08 AM   #1539
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I have read nearly every post on here and have the Phonoclone 3 boards, thanks RJM.

I have a few other phono stages I have built but this one looks intriguing. I am waiting on Comet Supply to send my Denon DL-301 Mk2 so I can finally build this and also test out my other MC phono stages.

Why does someone build MC stages without a MC cart? It's DIY sickness that's what it is.

Thanks should go to RJM for his time and effort in this, just answering all these questions deserves a lot of praise.
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Old 30th June 2011, 08:01 AM   #1540
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Hi Rjm,

I am enjoying the music from a phonoclone 3 I built with your help.
Essentially for easthetic reasons I am going to put the pcbs, already separated from the case trasnsformer, in a new chassis.

Can you tell or address me to a post where it is described how to minimise the noise level. At present I do not hear any noise from the listening position, but there is some noise with the ear near the speaker. To me it is not a trafo hum, but rather a very low rf noise.

Thank you

Renato
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