[rodge827]

Here's a Ten Tec 937 on Ebay.

http://www.ebay.com/itm/Ten-Tec-model-937-Power-supply-/261468189820?&_trksid=p2056016.l4276

[flavo]

Since my question about powering 2 of the 3116's wasn't as easy as I hoped it would be to answer.  Can anyone tell me if it's not really feasible? But if it is possible, what kind of parameters I would need to find in said PS?   I'm guessing that it would be OK to power 2 amps from one source? Would I just want double the volts and amps?
Thank you 

[OzarkTom]

Since my question about powering 2 of the 3116's wasn't as easy as I hoped it would be to answer.  Can anyone tell me if it's not really feasible? But if it is possible, what kind of parameters I would need to find in said PS?   I'm guessing that it would be OK to power 2 amps from one source? Would I just want double the volts and amps?
Thank you 

That one is over my head, but maybe someone here would know.

[flavo]

Thanks for commenting.
I made a post over on DIY if interested.
http://www.diyaudio.com/forums/power-supplies/255633-hopefully-sorta-simple-question-powering-chip-amp.html#post3912625

[jtwrace]

That one is over my head, but maybe someone here would know.

I'm probably not the one to answer but....you need two rails that are fused independently.  If you just sum the rating then if there is an issue, the fuse might not fail as needed.  That's not good.  Just split to have two rails and fuse appropriately and you will be fine. 

[rhing]

You can use this:

Power (Peak) = Voltage ^2 / 2 x Z

where Z = speaker impedance.

For a 12V power supply and 8 ohm speaker load, the calculated peak power is 9 watts. Considering the amp is 90 percent efficient, the power is probably close to 8 watts. If the speakers are inefficient, 8 watts won't go too far in producing low bass notes with authority.

I have an Astron RS-12A that I picked up locally through craigslist for $20 from a HAM radio enthusiast. The power supply was in mint condition, but I could tell it was an older unit by the looks of the vintage Sangamo 17,000uF tank cap and the early-1970's vintage Elna caps on the PCB. I finally got around to re-capping the power supply with a large Evox Rifa PEH200 21,000uF tank cap and low ESR Panasonic and Nichicon caps. The difference is night and day. The power supply as-is was good, but now I'm really hearing the Astron at its best. The soundstage is larger and deeper, the separation is better and the detail is much improved. Of course, the bass digs deeper too.



I'm going to add an IEC inlet to use better power cords and possibly add an audio grade fuse like a Furutech slo blo fuse. Right now, I'm powering my Sure Electronics TPA3110 amp, and it's amazing how much better this little amp sounds. This is my warm weather little integrated amp when I don't want to turn on my tube amps.

[lacro]

I'm going to add an IEC inlet to use better power cords and possibly add an audio grade fuse like a Furutech slo blo fuse. Right now, I'm powering my Sure Electronics TPA3110 amp, and it's amazing how much better this little amp sounds. This is my warm weather little integrated amp when I don't want to turn on my tube amps.

Hey Rich,
 Now that you have some time on your latest cap mod on the 3110, do you think it's a significant improvement?

[rhing]

The photo of my TPA3110 amp was taken when I had the Elna Silmic II 1,000uF/25V caps in there. I've since changed those to Panasonic FM 470uF/25V. To my ears, the sound is smoother, the tone is more organic. Some people describe it as being "wet" versus "dry." There has been no loss of bass going to the smaller capacitance. If anything, the bass is tighter. On the TPA3116 thread, wushuliu mentioned using Panasonic OSCON 330uF/25V organic semiconductor caps. I have those on order along with TDK X7R 220nF/250V ceramic caps for the amp bootstrap caps, and will try those in another Yuan Jing TPA3116 blue amp build along with those funky-looking Coilcraft shielded inductors.

Prior to the cap change, I thought the TPA3116 was superior to the lower powered TPA3110 in terms of casting a larger soundstage and better tone, but now I'm not so sure. With the re-capped Astron power supply, this amp sounds really sweet and musical. I have a single ended pentode EL84 amp project in the works. I really want to compare that tube amp to the TPA31xx amps, because these Texas Instruments amps have a tube-like quality to their sound.

As Tom has mentioned in this thread, it really is worth looking into a high current Astron or Ten Tec regulated linear power supply for these Class D amps. With 90% efficiency a lot of the electrons from the power supply end up at your speakers. A quality power supply and DC power cable is everything.

[rodge827]

A quality power supply and DC power cable is everything.

How does one construct a quality DC cable?
I'm using standard 18g wire with a Rat Shack connector and some banana jacks.

[rhing]

How does one construct a quality DC cable?
I'm using standard 18g wire with a Rat Shack connector and some banana jacks.

That's a good start. You want to use 18 gauge stranded Copper, preferably Teflon-insulated Silver-plated Copper stranded wire (Mil-Spec), that you can purchase at surplus electronic supply stores like Apex Jr. or through eBay. I used 16 gauge Mil-Spec wire in a twisted pair configuration. I slide spiral-cut tubing over that and finish it off with TechFlex expandable sleeving. For connectors on the amp end, I use Switchcraft 2.1mm x 5.5mm DC power connectors, although I have another cable that uses a Neutrik 4-pin XLR connector.

[rodge827]

Thanks rhing 

What size spiral cut tubing do you use?

Tech Flex size?

[OzarkTom]

Thanks Rhing for your observations and mods. I was curious if some cap mods on these power supplies might not make them even better, you have proven they are.

[HaroldHill]

I'm not sure I want to start tinkering under the hood here, but I'll peak out from my shell and ask: How do you know when it's time to start replacing caps?

rhing, are these the caps you were using for the tank caps?
http://www.digikey.com/product-detail/en/PEH200MJ5220MB2/399-5653-ND/2193731

[wushuliu]

Heck why not go for the gold:

http://partsconnexion.com/capacitor_ele_mundorf_plugin.html

[rhing]

Thanks rhing 

What size spiral cut tubing do you use?

Tech Flex size?

Either 3/16" or 1/4" should be fine for both.

I'm not sure I want to start tinkering under the hood here, but I'll peak out from my shell and ask: How do you know when it's time to start replacing caps?

rhing, are these the caps you were using for the tank caps?
http://www.digikey.com/product-detail/en/PEH200MJ5220MB2/399-5653-ND/2193731

Electrolytic caps typically have a life of about 20 years--that's whether they've been used or not. They age and can diminish in performance. I estimate that the caps in my power supply were easily over 20 years old, so they were due to be replaced.

The Evox Rifa (now Kemet) cap I put into my unit had similar specifications as the one you cited, except I bought mine from Mouser since they had them in stock.

Kemet PEH200MJ5220MU2........................ ....22,000uF/63V (without mounting screw)
Kemet PEH200MJ5220MB2........................ ....22,000uF/63V (with mounting screw, not required)

Even though my new cap has a chassis mounting screw on the bottom of the cap body, mine is lying on its side held down with ties.

Heck why not go for the gold:

http://partsconnexion.com/capacitor_ele_mundorf_plugin.html

I would have preferred the Nichicon Super Through or the Gold Tune audio-grade large capacitance caps, but I needed a cap with screw terminals with 25mm spacing. The Evox Rifa caps seem to have a good reputation for use in audio power supplies. Other candidates were the Kendeil's and BHC Aerovox Slit Foil screw terminal caps.

Today was turntable tune-up day where I tune everything up on my Kenwood belt-idler wheel drive turntable to make sure all my settings are re-calibrated. With my tube phono stage feeding directly into my Sure Electronics TPA3110, the music is pretty impressive.

[HaroldHill]

The Evox Rifa cap I put into my unit had similar specifications as the one you cited, except I bought mine from Mouser since they had them in stock. Even though my new cap has a chassis mounting screw on the bottom of the cap body, mine is lying on its side held down with ties.

Thanks, rhing, for the info on the shelf life of caps. Why was it necessary to lie the cop on it's side?

OzarkTom, thanks for pointing out these power supplies. I was skeptical at first, but you were right; my SL-11A makes my TPA3116d2 board sound better.

[rhing]

Thanks, rhing, for the info on the shelf life of caps. Why was it necessary to lie the cop on it's side?

This is the way that Astron designed the layout. The only thing mounting the PCB are the screw terminal attachments to the large filter (tank) cap. Without fastening the large cap with ties, there would be nothing keeping the PCB in place. It's not the best mechanical design, but it works and it makes great music with my TPA31xx amps.

[OzarkTom]

Here is a lot of big capacitors on Ebay for the Astron power supplies if anyone here is interested.

http://www.ebay.com/itm/lot-of-29-big-capacitors-for-ham-radio-power-supply-electronic-components-ASTRON-/380894773254?pt=LH_DefaultDomain_0&hash=item58af190006

[rhing]

Thanks, but those caps look like they have seen better days. For really good performance, I would buy new caps from a reputable source like Mouser, Digikey, Allied Electronics and Newark Electronics. The large caps in these linear power supplies are directly tied into those more expensive power transformers. If the cap goes, you risk catastrophic damage to the power transformer and possibly other parts of the power supply.

You can take your chances on used caps like the ones in the eBay listing, but you should have the capability of testing them and reforming (i.e., reconditioning) them, if they are out of specification. That still doesn't guarantee that they'll be reliable.

Also, if you ever consider replacing the large electrolytic power supply capacitor(s), you MUST know and understand how to safely and properly discharge a capacitor. Exercise extreme caution as the voltages that can potentially discharge could be lethal. There are many sources for this information on the Web. AC power is no joke.

[Speedskater]

For the most part the above warning applies to high voltage vacuum tube power supplies and to high current, very high power solid state power amplifiers.