[ClefChef]

Although I wasn't going to tweak for a bit, I couldn't resist trying this. Not that there was any problem with distortion or hiss (speakers silent with ear up close). But it makes sense that a higher input impedance would work better with the transformers (10k:10k nominally).

The eBay listing I bought the board from said gain was 36db, but the resistor (R2) that I removed from the board was 100k, which concurs with your (markvdv) assertion of 26db. I left the other resistor unchanged on assumption that the value did not have to match with datasheet value since it is a voltage divider and R2 is left open for 20db. I think I have read that this is OK?

Anyway, gain does seem reduced. The bass is stronger and the sound generally is weightier, although dynamics may be slightly less. Still, there is no shortage of dynamics. Overall, this is definitely an improvement. So if anyone else is tempted to try input transformers, my experience suggests to go for the lowest gain.

TI TPA3116D2 spec sheet Page 15.

In Master mode:

For 20db: R1=5.6K, R2 Open, Input impedance = 60k, input coupling caps = 1.5uf
For 26db: R1=20K, R2=100k, input impedance = 30k, input coupling caps = 3.3uf
For 32db: R1=39k, R2=100k, input impedance = 15k, input coupling caps = 5.6uf
For 36db" R1=47k, R2=75k, input impedance = 6k, input coupling caps = 10uf

26db seems to be more or less optimal.

[Markvdv]

For 36db" R1=47k, R2=75k, input impedance = 9k

I have no experience with transformer "coupling", tube guys can probably immediatly tell you how amps input impedance combines with 10k:10k transformer.

[dboy]

Hi clefchef - thanks for that but not sure you got the point. I do not have any input capacitors - the balanced inputs of the tpa3116 go directly to the secondary windings of a pair of Sowter 3575 signal isolating transformers. These transformers are the output stage of my es9018 Buffalo dac. There are no other caps, connectors or components other than wire & solder between the es9018 and the tpa3116. The goal is a simple/pure signal path for the most natural sound. It is a rather wonderful arrangement and I would encourage others to experiment with transformers instead of capacitors on the input pins of tpa3116. My post was to report that lowering gain to raise input impedance of tpa3116 to 60K provided best match with the transformers, resulting in better sound.

I would also encourage others to experiment with a Bybee Music Rail providing power to tpa3116. After a slightly shaky start this has turned out to be a great success for me - boosting the performance of an ultra-simple linear supply enormously. Takes bloody ages to burn in, so don't be fooled by that, but when it gets there it is downright remarkable. Haven't tried an Astron so cannot compare, but would be surprised if the Astron beat this. N.B. Partsconnexion currently has a 20 percent sale!

[dboy]

Cheers Markvdv, I am confident now that 20db gives best sound (in my unique arrangement). The bass is stronger, warmer and more detailed.

[ClefChef]

Hi clefchef - thanks for that but not sure you got the point. I do not have any input capacitors - the balanced inputs of the tpa3116 go directly to the secondary windings of a pair of Sowter 3575 signal isolating transformers. These transformers are the output stage of my es9018 Buffalo dac. There are no other caps, connectors or components other than wire & solder between the es9018 and the tpa3116. The goal is a simple/pure signal path for the most natural sound. It is a rather wonderful arrangement and I would encourage others to experiment with transformers instead of capacitors on the input pins of tpa3116. My post was to report that lowering gain to raise input impedance of tpa3116 to 60K provided best match with the transformers, resulting in better sound.

I would also encourage others to experiment with a Bybee Music Rail providing power to tpa3116. After a slightly shaky start this has turned out to be a great success for me - boosting the performance of an ultra-simple linear supply enormously. Takes bloody ages to burn in, so don't be fooled by that, but when it gets there it is downright remarkable. Haven't tried an Astron so cannot compare, but would be surprised if the Astron beat this. N.B. Partsconnexion currently has a 20 percent sale!

I got your point. The capacitor indication has nothing to do with input impedance, it just gives you the capacitor value for flat low frequency response given that input impedance. I agree that transformers are a lot better choice than capacitors, and transformers at the amplifier inputs could be used to accommodate balanced AND single-ended signal connection with ease (secondaries to TPA3116, primaries to signal +- for balanced or +to signal, - to ground for single ended).

I built a dac myself with transformer outputs (ASC LL88) and it sounded great.

[dboy]

I built a dac myself with transformer outputs (ASC LL88) and it sounded great.

Plug 'er in! The best input cap is no input cap! 

[mrrgb]

Heads up, SURE finaly has their TPA3116 board up on the BAY. 

Second comment is that the title for this thread appears to have a typo "TPS3116" rather than "TPA3116".  Can this be corrected? 

[Poultrygeist]

The Astron is taking the TPA to that 'set-like' performance...

I'm listening to the TPA with an Astron and it seems to be a huge upgrade.

There's room inside the Astron to mount a TPA and space on the back for connections.

Would this be a bad idea?

[Markvdv]

Some mentioned heatsinks Astron get very hot, how warm is it inside the Astron? The little Sure ceramics I know to be very temperature sensitive, don't know about the ceramics used on "audiobah" or if higher inductortemperature also means lowered inductance? Astron transformer could have some magnetic field to keep out off, and maybe TPAchip the other way could transmit polution into Astron? The TPA has all bad things a SMPS has, so you might need to shield the Astron from TPA.

[Poultrygeist]

Haven't noticed any heat from the Astron so far.

Seems like the TPA with HE speakers would be a very benign load.

[lacro]

Haven't noticed any heat from the Astron so far.

Mine runs stone cold too.

[thaddeussmith]

I'm dumb when it comes to electronics. I'm looking locally and on ebay for an Astron and often times some of the better deals are for 35 amps or more. Is that much power going to kill my little TPA3116, or will the board simply draw what it needs and no more?

[randytsuch]

will the board simply draw what it needs and no more?

Yes, it will just draw what it needs.
I just bought a RS-12A.  The TPA won't draw anything near what this Astron will put out, but it won't hurt anything.

Randy

[thaddeussmith]

Thanks!

I actually just found this tidbit on a HAM website as I was waiting for a response:

"Don’t worry about buying a power supply with too much current capacity. Your equipment will only draw the current it needs—no more, no less. In fact, it is probably safe to say that you can never have too much current capacity. It may seem economically foolish to invest $200 in a 25-A power supply when all you want to power is a 5-W handheld radio. However, if you think you’ll be upgrading to a larger radio in the near future, you may want to get the big power supply today (especially if you find a great deal on a high-current supply)."

[Markvdv]

Texas Instruments prints this for powersupply requirement in their setup guide.

Voltage Range Current Requirement
4.5 V to 26 V   8 A

[lacro]

Received this yesterday from Sure (12 days to eastern US). It's a 15W version of the TPA3110D2. However, when powered with my Astron PS at 13.8V, and low distortion, it's probably only 5-8W (see specs in link below). I had it up and running 5 minutes after it hit the door. Sure uses good packaging.

 It seems to have plenty of power to drive low efficiency speakers. The sound stage is huge, there is noticeably more information/detail in the music (over YJ Blue), plenty of bass, and very good separation of instruments, but it's slightly on the bright side. I don't hear any hum. hiss, or ringing yet. I think this board probably sounds better than the stock YJ blue/black board. I paired it with my 6N3 3-Tube preamp and it sounds even better. I requested a schematic from Sure, but don't know if they will comply.

I need to do a lot more listening/comparing with the my modded YJ blue board. The board is loaded with SMD's so probably not much in modding possibilities, at least not for me. The build quality is typical of Sure, everything is straight, true and the board is super clean. Oh...no turn on/off pop! This just might be a good choice for those not wanting to do mods.
 
Here's some close-ups of the board, maybe you guys can critique the layout, good/bad?





http://store.sure-electronics.com/audio/audio-amplifier-board/low-power-100w/aa-ab32996

Been listening for a couple weeks now, still think this board is a winner.....
As someone suggested on DIY Audio, I replaced the four 220uF electrolytics per side with a pair of 330uF Oscons. Definite improvement that's worth doing.

[rhing]

Thanks Lacro. Just what I need--another round of TPA31xx amps to purchase.

Did adding the OSCONs tame the brightness you mentioned earlier? Or did this seem to fade as you burned in the amp?

[lacro]

Thanks Lacro. Just what I need--another round of TPA31xx amps to purchase.

Did adding the OSCONs tame the brightness you mentioned earlier? Or did this seem to fade as you burned in the amp?

I know your not going to sit back and watch others have all the fun

The brightness subsided after 10 hours or so of play time with the stock board. The Oscons just made everything smoother (after burn in), and really enhanced the base. I wonder if four more would help even further?

[Folsom]

I know your not going to sit back and watch others have all the fun

The brightness subsided after 10 hours or so of play time with the stock board. The Oscons just made everything smoother (after burn in), and really enhanced the base. I wonder if four more would help even further?

More bass likely

[rhing]

I know your not going to sit back and watch others have all the fun

The brightness subsided after 10 hours or so of play time with the stock board. The Oscons just made everything smoother (after burn in), and really enhanced the base. I wonder if four more would help even further?

Of course not. I ordered a TPA3116 amp from Sure Electronics this morning. It does seem that the brightness and sibilance does subside as these amps break in. The Panasonic OSCONs really do a nice job with these Texas Instruments amps. I would try adding a couple more and see what happens. Like Salis Audio said, you'll probably get more bass, but not in the sense that it will be more boomy or flabby. This, of course, will depend on the frequency range of your speakers.