The Phonoclone and VSPS PCB Help Desk

[rjm]

No disasters, give it a whirl: worst case it may sound a little rolled off.

[rjm]

Originally Posted by pfcs49

As an aside, I measured the input capacitance: long side 93pF/short side 87pF.
I kinda expected a little less. ???

I've just measured the capacitance of the VSPS 300 board inputs (bare board), and it is 10 pF. I would expect <20pF for the short length of twisted wire and connector, for a total "true" capacitance of about 30 pF.

Anyway, it's all small and of no consequence compared to the capacitance of the phono cable itself. Nothing to worry about.

[WntrMute2]

Originally Posted by WntrMute2

So I'm running my Sumiko Blackbird into my DIY VSPS but I want to listen to it through the Phonoclone I've built. Assuming I select the correct resistors for R1 and R2, will this work without damaging something? The output of the Blackbird is 2.5 mv and the internal resistance is 135 ohms. This works out to R1=135 and R2=540. Any disasters up ahead if I do this?

OK, I just got my resistors for the above Phonoclone and have another question. For R1=135, should I undershoot with a resistor value of 121ohms or overshoot with 150ohms? Same thing for R2=540, under at 511ohms or over at 562ohms. Thanks in advance.
Dave

[rjm]

Undershoot. Not that it makes any difference, but any decision is better than none.

[jcowling]

Building my Phonoclone 3 and power supply. Just a couple of newbie questions:

1. What gauge wire should I use for the connections to the RCA jacks? Should it be solid copper or stranded wire?

2. What kind of wire is used for the connector between the power supply and the audio plug that plugs into the phono preamp? A microphone cable? A power cable? Can I just cut up a PC power cable and use that? It looks like it is a three wire cable, but I can't seem to find a source for less than a 100 feet of three wire cable.

3. My transformer did not come with any hardware. What is the metal cap in the pictures below called? I don't know what to look for on Digikey or Mouser. I guess I don't need one, but it looks like it holds the transformer in place nicely.

I am using these pictures as my guide, which I found on this help forum.





Thanks.

[rjm]

Originally Posted by jcowling

1. What gauge wire should I use for the connections to the RCA jacks? Should it be solid copper or stranded wire?

You can use whatever you feel comfortable with. Solid core 24 AWG works quite well.

Originally Posted by jcowling

2. What kind of wire is used for the connector between the power supply and the audio plug that plugs into the phono preamp? [...] Can I just cut up a PC power cable and use that?

YES!! That works just great.

Originally Posted by jcowling

3. My transformer did not come with any hardware.

Unless your transformer has a potted "plug" with a hole drilled in it, you will need those rubber/metal plates and the bolt. I doubt these are available off the shelf at digikey, I've only ever seen them included with a transformer. However it's not too hard to make a bracket yourself from a bit of wood or plastic. It doesn't have to be round.

[WntrMute2]

I used wire from this guy. Very easy to deal with and great quality stuff.
eBay My World - navships. I used the 24 gauge stuff.
For the power cords and umbilicasl, hardware stores as well as Home Depot type stores have 14/3 black cord in bulk for a buck a foot type prices.

[WntrMute2]

Originally Posted by WntrMute2

OK, I just got my resistors for the above Phonoclone and have another question. For R1=135, should I undershoot with a resistor value of 121ohms or overshoot with 150ohms? Same thing for R2=540, under at 511ohms or over at 562ohms. Thanks in advance.
Dave

I went with the overshoot resistors. Sounded fantastic on start-up! Have ran a few albums thru it and it keeps getting better. The wife came down into the basement to fold clothes and said "I've never heard the instruments sound so distinct from each other or it sound so lifelike." Really, I swear! Phonoclone with HOMC works just fine at least so roar.

[Woody1911a1]

lol , 24 g , just grab a few feet of cat5 . it's already twisted

[sandbasser]

Originally Posted by Woody1911a1

lol , 24 g , just grab a few feet of cat5 . it's already twisted

I've often wondered about recycling Cat5... What do you do??? Strip the shielding off and break it down into the 4 pairs???

Thanks,