Are there any cheap options for a Better Touch Power Supply?

[bigbwb]

This is my thread I started recently on the same topic.....
http://www.audiocircle.com/index.php?topic=82815.0

As of now, the PE PS arrived today, I am awaiting the arrival of the new resistor to make the 6v setting 5v instead. My father in law is an EE and will do the surgery

Trust me, I was very skeptical about adding an aftermarket PS but a buddy of mine plus many other Touch/SB owners felt this one helps a bit. For $30 or so shipped with the connector kit, its a no brainer to try at least.

Good luck!
Brandon

[JohnSwenson]

Hi John

I'll bite...would it be possible to post a schematic of your favoured supply?

Thanks

Here is the design:

http://johnswenson1.home.comcast.net/stereo/SB_5V.GIF

As shown its good for up to 2A load which should be fine for a Touch by itself. If you want to go with an external USB drive its probably best to go with a beefier transformer. The VPS20-2200 should do (with the secondaries in parallel) or if you really want to go with the big monster the VPS20-4000 (secondaries in parallel).

The Hammond choke is a little hard to find, but do NOT leave it out, its the heart of the design. With the choke the max current pulse through the transformer is many many times less than it would be if it was just a cap input filter. This radically cuts down on noise sent back into the mains. Also whats going into the regulator is almost a pure sine wave, no high frequency harmonics. This means the regulator can easily filter the ripple out. With a single cap filter there are large amounts of high frequencies going to the regulator. The off the shelf IC regulators are not so great at filtering out these high frequency components, which is one of the reasons for the complicated discrete regulator designs popular with some "audiophole" designs. In this design you are adding a fairly expensive choke ($25-$35) and a simple cheap regulator VS simple cap filter and complex expensive regulator. I went with the simple approach.

This is a very carefully tuned designe so be very careful with using different parts, even things such as different brand or model caps can change the behavior significantly. If at all possible I would stick with the specified transformers. They are good quality transformers with high isolation between primary and secondary and don't cost a lot. Its probably going to cost 4 times as much to find a transformer that will outperform these.

Have fun,

John S.

[tonyptony]

John, what cap type is C1? And what about R1?

I thought the LT1064 was out of production for quite some time. Is there a replacement that you know will provide the same performance in this circuit?

[iPhone]

This is my thread I started recently on the same topic.....
http://www.audiocircle.com/index.php?topic=82815.0

As of now, the PE PS arrived today, I am awaiting the arrival of the new resistor to make the 6v setting 5v instead. My father in law is an EE and will do the surgery

Trust me, I was very skeptical about adding an aftermarket PS but a buddy of mine plus many other Touch/SB owners felt this one helps a bit. For $30 or so shipped with the connector kit, its a no brainer to try at least.

Good luck!
Brandon

Glad to hear you have an open mind after spending money that you probably didn't need to. The Touch has internal switchers inside it after the DC Mains (even for the 5VDC power) so adding a linear power supply should have no affect whatsoever unless ones OEM PS stopped working!

The external 5VDC goes to an internal switcher to be stepped up to 10VDC so it can be regulated with an internal linear 5VDC PS. Seems kind of silly to go from AC mains to External Linear 5VDC PS then stepped up internal switching 10VDC to internal linear 5VDC.

So I see four reasons to upgrade the OEM supply. The OEM supply no longer works, is causing a ground loop issue, is putting noise into other equipment, or one just has extra money laying about that one doesn't want to spend on CDs instead.

[Phil Leigh]

Glad to hear you have an open mind after spending money that you probably didn't need to. The Touch has internal switchers inside it after the DC Mains (even for the 5VDC power) so adding a linear power supply should have no affect whatsoever unless ones OEM PS stopped working!

The external 5VDC goes to an internal switcher to be stepped up to 10VDC so it can be regulated with an internal linear 5VDC PS. Seems kind of silly to go from AC mains to External Linear 5VDC PS then stepped up internal switching 10VDC to internal linear 5VDC.

So I see four reasons to upgrade the OEM supply. The OEM supply no longer works, is causing a ground loop issue, is putting noise into other equipment, or one just has extra money laying about that one doesn't want to spend on CDs instead.

I really believe it is your 3rd reason that affects some peoples systems but not others. That is why when we diff the DAC nothing shows - it's NOT the DAC output that is changing... it could be what comes out of the pre-amp/power-amp...because of what is being re-injected back into the mains (or maybe RFI).
Just a theory.

[JohnSwenson]

John, what cap type is C1? And what about R1?

I thought the LT1064 was out of production for quite some time. Is there a replacement that you know will provide the same performance in this circuit?

Its the LT1084, very much still in production. I just checked Digikey and they have 384 in stock.

I use half watt carbon composition for R1 and polypropylene orange drop for C1.

John S.

[Phil Leigh]

I use half watt carbon composition for R1 ...
John S.

Not Vishay? ...

[Mr_Sukebe]

Has anyone here tried a Touch with a TeddyPardo PSU? Any thoughts?

[JohnSwenson]

Not Vishay? ...

Nope, strange as it might seem to the audiophile mind the cheap carbon comps are actually the best resistor for this task.

John S.

[tonyptony]

Its the LT1084, very much still in production. I just checked Digikey and they have 384 in stock.

I gotta get new glasses! :-)

How about adding a LED for power on indication? Would that effect the output in any way?

I also have a beautiful 8VAC output R-Core transformer from Japan. Apart from having to drop the output voltage a bit, where do you think the differences would be (measurement-wise) if I used something like this?