[Markvdv]

 There might be some people reading this thread that do not have the 3110 amp discussed.
Nice to continue a discussion based on data PE specifies for a SureTPA3110, but better check TI datasheet. The TPA3110 is a 2x3watt amp at 8 ohm at 1%THD IF it is supplied by minimum voltage it can operate on: a 8V powersupply.

I bet most people here have a 12V powersupply, maybe even higher??? For a 12V powersupply the tpa3116 at max 1%THD will deliver with a pair of OvernightSensation 83dB 8ohm speakers around 94dB SPL at 1 meter. In other words it is a 2x8watt into 8ohm amp when coupled to a 12volt powersupply.

[Markvdv]

  and ~93dB SPL with overnightsensation at 0.06% THD (5watt)
the 94dB above should be 95dB:D

[shadowlight]

Couple of post back some had mentioned smsl sa-36a pro which has tpa3118 chip.  iPrice is pretty good at 40 bucks shipped.

http://www.shenzhenaudio.com/smsl-sa-36a-pro-20wpc-tpa3118d2-digital-amplifier-power-adapter.html

[Markvdv]

Do you have experience with seller?

[shadowlight]

Do you have experience with seller?

Nope, was just searching and came across the seller.

[wushuliu]

Couple of post back some had mentioned smsl sa-36a pro which has tpa3118 chip.  iPrice is pretty good at 40 bucks shipped.

http://www.shenzhenaudio.com/smsl-sa-36a-pro-20wpc-tpa3118d2-digital-amplifier-power-adapter.html

Provided any of those components are genuine, that seems like an interesting option: they're using multiple caps for the PS for instance a la Salis Audio's recommendation for low ESR, which is a first.

Features english translation is hilarious.

SMSL products are not bad and have a decent rep.

[cody69]

Since my unit will see occasional use, I want to have a switch to shut the power off. With a "brick" type laptop power supply, where's the right place to put the switch -- in the AC 110v line or the 18.5v DC line?
Like PG and a few others, I plan to put the power supply inside the chassis, so either side of the power supply can be switched.

I realize either will shut off power to the unit, but I'm unclear if switching off current on the DC leg will prevent current from flowing on the AC -- I want to avoid any power consumption when the unit is shut down.

[matt_garman]

Since my unit will see occasional use, I want to have a switch to shut the power off. With a "brick" type laptop power supply, where's the right place to put the switch -- in the AC 110v line or the 18.5v DC line?
Like PG and a few others, I plan to put the power supply inside the chassis, so either side of the power supply can be switched.

I realize either will shut off power to the unit, but I'm unclear if switching off current on the DC leg will prevent current from flowing on the AC -- I want to avoid any power consumption when the unit is shut down.

I vote you switch on the AC.  Minor reason: there was some talk on the diyaudio forum tpa3116 thread about sparking when switching on the DC.

But the bigger reason is that even with the DC shutoff, the power brick probably draws some current.  Search the web for "phantom energy loss".  It's unlikely to be much current, but, for example, say you're running entirely on solar power (off grid), and need to make every watt-amp count: opening the circuit at the AC level guarantees no phantom losses.

[Poultrygeist]

I've done it both ways and haven't found an advantage one way or the other.  When I had a very long cord it made sense to install at the 110v line and if you make a bad splice you can easily replace the detachable power cord.

The 18v dc line is harder to splice so I used a coaxial power jack from Radio Shack ( #274-1582 ) and ran leads off it to the power switch. I installed it internally using a small bolted down L bracket so the brick resides onboard.

I use a slow blow fuse before the switch.

[cody69]

But the bigger reason is that even with the DC shutoff, the power brick probably draws some current.

The 18v dc line is harder to splice

Thanks. Looks like switching the AC is best. Another question regarding volume control with a TPA3110 in a computer desktop audio setup:

Thoughts between installing a POT as outlined in this thread, paired with a fixed output DAC... vs...
Using a DAC with volume control (eg., Dragonfly that controls the analog signal) paired with a TPA3110 configured as a power amp?

I'm attracted to the simplicity of PC/DAC volume control with no moving parts, what are other issues to consider?

[wushuliu]

[matt_garman]

Thanks. Looks like switching the AC is best. Another question regarding volume control with a TPA3110 in a computer desktop audio setup:

Thoughts between installing a POT as outlined in this thread, paired with a fixed output DAC... vs...
Using a DAC with volume control (eg., Dragonfly that controls the analog signal) paired with a TPA3110 configured as a power amp?

I'm attracted to the simplicity of PC/DAC volume control with no moving parts, what are other issues to consider?

One thing you might want to think about is that software volume controls can be sub-optimal.  It depends on several factors, but consider the case where you're listening to CD audio: you have 16 bits to represent the waveform of the sound.  Volume is extra information that won't "fit" into those 16 bits without first "making room".  A naive or poorly implemented volume control will remove precious waveform information to make room for the volume data.

This is my use-case: 99% of what I listen to is FLAC audio files ripped from my CD collection.  My intent is to send to my DAC the exact same bitstream as if I was using a CD player.  I don't want the operating system or any software to do anything to that bitstream.

However, it appears to me that smart software can preserve the original waveform and add volume information by increasing the number of bits, e.g. 16 bits of CD audio waveform data plus 8 bits for volume info equals 24 bits.  Don't hold me to this, as that's just my assumption looking at the options in Foobar2000.

Personally I like having a physical volume control; I find it more ergonomic than software volume controls.  But I think that's a matter of personal preference.

If the software can truly do it correctly (i.e. without altering the original waveform), then I don't think there is a right or wrong.  If you're going to have physical volume controls, however, then you do need quality hardware (potentiometers, stepped attenuators, etc).  I know the high-end ALPS brand pots are popular; I have no experience with them other than knowing they are expensive.  However, earlier in this thread the Panasonic EJV 50k pot (Digikey part number P2G1503-ND) was mentioned.  This costs less than $2 and at least I can't detect any sound quality degradation with these tpa311x amps.  So if you prefer the physical volume control, I think you'll find it hard to be the EJV.

Look back a ways in this thread, I forget who did it, but someone built an external volume control with the Panny EJV in an Altoids tin.  (There were pics posted).  This is a great cheap way to give these pots a try without any real risk.

[matt_garman]

Wow, that's epic!  Do you have a stock board to compare to the "transformer"?  Is that board fragile with all that stuff hanging off it?  I'd be afraid to move it for fear of busting something off!

Pretty nice!

[lacro]

Awesome!! have you listened yet?

[wushuliu]

Haven't the time yet. hopefully soon...

[rhing]

Nice work wushuliu. You really took advantage of the Yuan Jing blue amp's thru-holes for modification, which is the main advantage of this design.

[wushuliu]

Nice work wushuliu. You really took advantage of the Yuan Jing blue amp's thru-holes for modification, which is the main advantage of this design.

Yes, this board is a joy to work with in terms of desoldering and space. Took me only a fraction of the time to mod compared with other boards.

[thaddeussmith]

can you run down a list of the components you used, for those of us who can't recognize such things on the spot with an unclear picture?

[wushuliu]

can you run down a list of the components you used, for those of us who can't recognize such things on the spot with an unclear picture?

Coilcraft SER2915L 10uh inductors
TDK .22uf 250v X7R caps (bootstraps)
330uf 25v Panasonic hybrid electrolytics (PS caps)
Wima FKP, MKP, and MKS for .68uf,10nf, and 1nf output filter caps
36db gain resistor setting
Dayton MKP 2.2uf input caps
Jantzen Superior 2.2uf input caps

Amp sounds *excellent*. Clean and clear, no grain or edge. *Pure*.Best build yet. All done now w/ the TPA. Ready to move on.

I do want to get one of those power supplies that I think someone keeps mentioning. What are they again?

[thaddeussmith]

Are you talking about the Astron power supplies?

http://www.hamradio.com/detail.cfm?pid=H0-004423