JLTi phono preamp - upgraded power supply?

[Kenreau]

I've got the basic wall wart PS to go with my JLTi phono stage.

I'm looking for diy or cost effective upgraded power supplies. The $900+ for the upgraded JLTi oem ps is out of my budget.

I conducted a number of searches but only came up with mention of the stock / oem upgraded PS. In the Positive Feedback review by Roger Gordon, there was mention of some JLTi users experimenting with DIY upgraded PS but I haven't had any success in finding out what those PS were (I attempted to locate Rogers email address, but was not successful).

I've read favorable posts mentioning Acopian as a quality off-the-shelf PS. They range +/- $200. My budget target range is $300 to $400.

The power supply needs are output 16VAC~to~18VAC with 1.25 Amps.

Has anyone see plans, articles, or made a custom PS for
this unit? Or is there a suitable power supply someone could recommend? Off the shelf manufacturer or DIY assembly with parts and pc board would be great (ala Pass Pearl or similar).

Thanks
Kenreau

[h_a]

You sure about the current rating? I don't remember any phono stage that draws more than 1 A.

Have fun, Hannes

[Andy Bartha]

From your description the wall wart seems to be A/C output between 16 and 18v A/C. Find a good quality E I transformer of same voltage and close to the same current. No toroids, thay pass more high frequency crap than an E I type. Current wise you need to have the exact same or a bit more current. Do not use anything with less current or the transformer will get hot.
Once you have the transformer you need to test it for output voltage. It will be some what higher unloaded, maybe 5 to 6 volts A/C, this normal. You want to use the 15v figure, 15 + 6 is 21, so if your transformer measures 21v unloaded you are in the ball park.
You then will need to chose a cabinet. I would recommend something plastic to keep magnetic interaction with the cabinet to the minumum. Mount a long cable going to the phono stage so you can keep the power transformer as far away as you can to keep the magnetic hum created by the power transformer away from the phono stage. All this should cost less than 100.00. The rest of your budget you use to upgrade power supply parts in the JLTi phono. Look at the power supply diodes and the caps and upgrade them as needed and maybe a better output coupling cap. This is just a start there many other things that can be done to upgrade the JLTi.

[Kenreau]

Originally Posted by h_a

You sure about the current rating? I don't remember any phono stage that draws more than 1 A.

Have fun, Hannes

This is what I was provided...AC range of 16V to 20V is acceptable but he recommends 17V or 18V, and 1.25A.

Thanks
Kenreau

[Kenreau]

Originally Posted by Andy Bartha

From your description the wall wart seems to be A/C output between 16 and 18v A/C. Find a good quality E I transformer of same voltage and close to the same current. No toroids, thay pass more high frequency crap than an E I type. Current wise you need to have the exact same or a bit more current. Do not use anything with less current or the transformer will get hot.
Once you have the transformer you need to test it for output voltage. It will be some what higher unloaded, maybe 5 to 6 volts A/C, this normal. You want to use the 15v figure, 15 + 6 is 21, so if your transformer measures 21v unloaded you are in the ball park.
You then will need to chose a cabinet. I would recommend something plastic to keep magnetic interaction with the cabinet to the minumum. Mount a long cable going to the phono stage so you can keep the power transformer as far away as you can to keep the magnetic hum created by the power transformer away from the phono stage. All this should cost less than 100.00. The rest of your budget you use to upgrade power supply parts in the JLTi phono. Look at the power supply diodes and the caps and upgrade them as needed and maybe a better output coupling cap. This is just a start there many other things that can be done to upgrade the JLTi.

Thanks Andy. I just noticed you are in Oregon. I'm in PDX. I recall buying some of your Whatchamacallits years ago. Is this PS possibly something I could pay you to build for me? Maybe shoot me a pm?

Thanks
Kenreau

[h_a]

It seems to me the current specs are already way overkill (has your phono stage large heatsinks? ;-)) ) and as I see now the whole power supply is already build into your phono stage with the exception of the transformer.

Don't know what the improvement will be if one changes only the transformer, however you could also use a line filter in your new supply.

Have fun, Hannes