cheap 12v linear power supply

Odal3 · « **Reply #100 on:** 14 Sep 2014, 12:22 am »

Thanks Rhing & PG for the info - Much appreciated.

steve in jersey · « **Reply #101 on:** 14 Sep 2014, 03:34 am »

Ok guys, I need a 12v LPS for my Auraliti PK100 Digital File Player.

Which Astron model do I get ???

Markvdv · « **Reply #102 on:** 14 Sep 2014, 07:17 am »

Quote from: Salis Audio on 13 Sep 2014, 08:49 pm

It acts more as a power reservoir, so having a little longer leads isn't going to be as noticeable as the performance gain from a substantially better capacitors. The decoupling of RF and what not is a job taken care of to a much larger degree by a few smaller capacitors, and capacitors in your load. Think of the distance the wires run to the load from the PSU, a very small run on this cap is going to be like having a slightly longer umbilical cord.

What you can however do is mount another small cap with leads that are very short directly to the pads. However I'm going to give you a little bit of a different recipe. Use a 1uf film, and the cheapest, crappiest, 300-400uf cap you can find. Solder them as short of leads possible right onto the pads, and then have the large one mounted off board.

You can even use a couple of these. 871-B32560J1105K

and maybe this will be a crappy enough capacitor 647-UVR1E331MPD1TD . If you have any cheap capacitors from a chinese product use one of those, some off-brand cap.

So main difference between Cornell Dubilier SLP and Kemet PEH for sound would be the 4000uF difference, not ESR, withstanding ripple is only life expectance?

lacro · « **Reply #103 on:** 14 Sep 2014, 01:13 pm »

Quote from: Salis Audio on 13 Sep 2014, 08:49 pm

It acts more as a power reservoir, so having a little longer leads isn't going to be as noticeable as the performance gain from a substantially better capacitors. The decoupling of RF and what not is a job taken care of to a much larger degree by a few smaller capacitors, and capacitors in your load. Think of the distance the wires run to the load from the PSU, a very small run on this cap is going to be like having a slightly longer umbilical cord.

What you can however do is mount another small cap with leads that are very short directly to the pads. However I'm going to give you a little bit of a different recipe. Use a 1uf film, and the cheapest, crappiest, 300-400uf cap you can find. Solder them as short of leads possible right onto the pads, and then have the large one mounted off board.

You can even use a couple of these. 871-B32560J1105K

and maybe this will be a crappy enough capacitor 647-UVR1E331MPD1TD . If you have any cheap capacitors from a chinese product use one of those, some off-brand cap.

Your recipe sounds like a plan, but why a 'cheap' 300-400uF cap? Also, any suggestions for a big cap if I am remotely mounting it. It doesn't have to have screw terminals, and lead spacing isn't an issue. I could possibly fit a 2" X 4" beast in there if I move the transformer to the right (no big deal). However, I would really like to use something in the 1-1/2" - 1-3/4" diameter range if possible, and under 4" long.

Folsom · « **Reply #104 on:** 14 Sep 2014, 09:45 pm »

The cheap one will act like a dampening device, as its ESR and leakage is higher.

randytsuch · « **Reply #105 on:** 15 Sep 2014, 12:01 am »

Quote from: Salis Audio on 12 Sep 2014, 12:49 am

For audio gear I would dampen the transformer from the primary side. Secondary snubbers aren't often appreciated by some pretty serious people on DIYaudio. Good idea, but the result isn't what you want.

Missed your reply before
There's a long thread at diyaudio about measuring for adding secondary snubbers
http://www.diyaudio.com/forums/power-supplies/243100-simple-no-math-transformer-snubber-using-quasimodo-test-jig.html

And I'm not sure what it would do on the primaries, I think you need to add the snubber to compensate for the secondary side of the tx, like capacitance of the secondary windings.

I did add the RC network to my DAC the other day, and I think it improved it, although it was pretty subtle.

Randy

Folsom · « **Reply #106 on:** 15 Sep 2014, 06:09 am »

Dampening can happen through the primaries to the secondaries.

Some people are into snubbers. They often look great on paper, others think they do some very wrong things. The solution of avoiding the issues of them on the secondary, is to dampen through the primary. If you're interested in this, I'll ask my guy who's into resonation control more than I am.

randytsuch · « **Reply #107 on:** 15 Sep 2014, 11:27 pm »

Quote from: Salis Audio on 15 Sep 2014, 06:09 am

Dampening can happen through the primaries to the secondaries.

Some people are into snubbers. They often look great on paper, others think they do some very wrong things. The solution of avoiding the issues of them on the secondary, is to dampen through the primary. If you're interested in this, I'll ask my guy who's into resonation control more than I am.

Sure, I'm, interested. It doesn't make sense to me that it would be better to dampen on the primary, but there is a lot of things I don't understand.

Randy

JDUBS · « **Reply #108 on:** 15 Oct 2014, 01:06 am »

Quote from: Poultrygeist on 10 Sep 2014, 08:13 am

The older and IMO better units do not have an IEC.

So, is this still the way to think here with the Astron? Be on the look out for an older model with non-detachable cord or a newer model with IEC? I guess it comes down the willingness to DIY some mods?

Thanks,
Jim

Odal3 · « **Reply #109 on:** 30 Oct 2014, 05:15 am »

I can report back that Astron SL-15 works great as well. Note that the outer "shell" used for integrated mounting of the HAM radio can be removed but it left 2 "posts" in the front two corners that I had to cut off. I had planned to put the TPA3116 in the empty space but the shell was unfortunately bent at arrival, but I'm not the one to complain since I picked up a used one for only $5.

Here's a picture of the power supply with the shell:
http://www.theantennafarm.com/catalog/images/Astron%20SL-15CDM.jpg

rodge827 · « **Reply #110 on:** 30 Oct 2014, 10:17 am »

Odal3, Take it to an auto body shop and see if it can be bent/banged back into place enough to fit your amp.

Odal3 · « **Reply #111 on:** 31 Oct 2014, 05:17 am »

Thanks for the tip - already found another enclosure for it so I'm already happy as is. BTW: While looking into different paint options to get rid of the scratches on the Astron, I came across a page showing an alternative usage for the Astron: Here's a recipe how to use an Astron to convert a scratchy metal surface into a new "decorative, durable, corrosion-resistant, anodic oxide finish". The website shows how an old receiver is rescued.

http://www.ai4ji.com/Projects/anodizing.htm

However, my wife would throw me out if she caught me in the kitchen boiling an amp case on the stove.

gychang · « **Reply #112 on:** 17 Dec 2014, 01:54 am »

I am sold on linear amplifier!!, bought ten tac 927 from ebay and at first I heard significant humming noise from transformer and I finally figured out it was due to partly loose cover and I had the amp setup on a heavy furniture and it was the furniture that was vibrating and causing the noise.

I was somewhat surprised to put it on the stone countertop and it is nearly dead quiet (about 1/2ft away I can hear transformer), and now the sound is impressive on my TDA7297 amp. Various wallwart is hit and miss, and nice linear PS is indeed very impressive.

Folsom · « **Reply #113 on:** 17 Dec 2014, 02:12 am »

If you want a serious upgrade to you TDA7297 get some Belden 8412 for speaker wire. Attach the shield to circuit ground. DO NOT attach negative output to the shield.

The TDA7297 outputs are balanced. They need the shield, and for it to be grounded correctly.

Run the shield as close to the output terminals as you can.

gychang · « **Reply #114 on:** 17 Dec 2014, 09:52 am »

Quote from: Salis Audio on 17 Dec 2014, 02:12 am

If you want a serious upgrade to you TDA7297 get some Belden 8412 for speaker wire. Attach the shield to circuit ground. DO NOT attach negative output to the shield.

The TDA7297 outputs are balanced. They need the shield, and for it to be grounded correctly.

Run the shield as close to the output terminals as you can.

I have the wire and not clear on exactly where to solder the shielded portion of the wire. I attached the generic picture (I have your mod). My case is nonmetallic and I have 2 prong DC coming into the amp as expected. Also not clear on "close to the output terminals..."

I am very interested in doing this correctly.

Folsom · « **Reply #115 on:** 17 Dec 2014, 01:48 pm »

I just mean the most full coverage you can have, the better, all the way up to the board. The shield would connect to the - DC terminal in your picture. This could be done with another small wire soldered to the shield tails.

Remember, the - for outputs is not a ground, so whomever is reading don't think you can connect the shield there.

gychang · « **Reply #116 on:** 17 Dec 2014, 03:58 pm »

Quote from: Salis Audio on 17 Dec 2014, 01:48 pm

I just mean the most full coverage you can have, the better, all the way up to the board. The shield would connect to the - DC terminal in your picture. This could be done with another small wire soldered to the shield tails.

Remember, the - for outputs is not a ground, so whomever is reading don't think you can connect the shield there.

Here we r using Belden wire as the speaker wire or as a shielded input?

Odal3 · « **Reply #117 on:** 17 Dec 2014, 04:51 pm »

Does anyone have a recommendations for good quality dc power jacks and plug for an Astron powering one maybe two TPA 3116 amps. What sizes and ratings are recommended?Looked at partsexpress and theirs were rated at no more than 3 A. Switchcrafts were mentioned earlier.

Odal3 · « **Reply #118 on:** 17 Dec 2014, 04:58 pm »

Almost forgot, there is a lot if humming from my Astron. Can hear it when no or very soft music. No difference if connected to the amp or not. Added woodblock underneath made it worse, and added some weight to the top took away some of the lower hum but made it more high pitched instead. There is no diff if put on a concrete floor or if removing the top metal cover so I can see the internals. What do you think is causing this and whats the best and easy fix?

Folsom · « **Reply #119 on:** 17 Dec 2014, 05:54 pm »

Speaker wire, gychang

If Astron hums bad you may have DC on your AC in house.