Nice work Matt! It's interesting you don't hear a difference with the Nichicon over the Oscons caps. I have been waiting for that info before I build my 3110 into a box. It's still my favorite class D amp.
I have a couple of questions: It looks like your stand-offs are metal, making the board grounded to the chassis. Is that correct? Where did you get the box? Also, the LED (part #).
I don't know how much difference it makes, but those terminal blocks are made mostly of steel. The screw, and the bottom pinch block are steel, only the top pinch block is non ferrous.
Let me qualify that a bit: I didn't do any explicit A/B testing between the OSCON 3110 and the FPCAP 3110. I've been happily using the OSCON 3110 for a while now (the new Sure 3110 is also my favorite). When I finished the FPCAP 3110, I just plugged it in and did a comparison from memory. Going off my memory is always a scary proposition! So, there very well could be some nuanced differences between the two, I just haven't taken the time to really test. I would like to do that at some point though.
Yes, I've done all my amps this way, mainly because metal standoffs are what I have on hand. I don't think I've tried non-conductive standoffs with the tpa3110, but in playing with the tpa3116 boards, I never noticed any difference in using metal or non-metal standoffs. But I also never paid much attention to it either way. 🙂
The box was from China via eBay. The current listing title is "B-0905 Full Aluminum Enclosure / mini amplifier case/ Preamp box/ PSU chassis" from seller along1986090. The listing shows a silver front face: I emailed the seller in advance of the purchase to see if he could do black, and he could. Note there seems to be lots of people selling this "B-0905" chassis.
The LED is DigiKey part number 67-1151-ND. The manufacturer is Lumex Opto/Components Inc, part number SSI-LXR3612ID.
You can't see it, because I covered it with heat-shrink tube, but there's a resistor in series with the diode's anode. I think I used a 1.5k ohm, IIRC. Otherwise, it's a retina burner!
Note the front panel of that case is thicker than the threaded part of the LED, so I couldn't screw the nut on. Instead, I simply used glue to hold the LED in place. That's also the reason why that switch is so massive, it's the only one I could find with a threaded shaft long enough to be usable with that thick front plate.
Are you suggesting that that is a potential for performance degradation? I gave some serious thought to doing away with the terminal blocks and direct-soldering the leads to the PCB... but the terminal blocks are just so convenient!
Any chance of some pics with the lid off?
Which tpa3110 board are you using?
Did your tpa3110 boards come in PBTL mode, or did you convert them? If you converted, how did you do it?
Also, what were your reasons for going PBTL?
AC1103 with some changes, ao Wurths 10uH both solids and 2200uF NCC, ~30W with 2 PSU's for them also sold by AC where also some parts were replaced. Standard PBTL but same pcb's also available BTL, gain was very very high, I think maximum, reduced it.
Bottomplate is cover, has the pcb's which have wires to bindingposts...and pot, nylon standoffs btw. But opening tiny amp isn't really 123 easy LOL wires aren't very long, soldered onto pcb's. Very low profile Hammond 1434 case, (much) bigger ones often used for tube-amps.
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Matt - Thanks for the info.....
I don't know if there is performance degradation, I just have seen it mentioned that steel (iron) doesn't belong in audio connections.
As for the thick front plate on you amp. I know what you mean about the threads not being long enough. Here is a solution. You can counter-bore the back side of the front plate, so the plate is thinner where the threads are.
You can use a cheap wood cutting spade bit as a counter-bore to cut the aluminum if you use cutting oil (for aluminum). You want the type of bit without the wings, see below. Attach the plate to a block of wood, and stand on the block while drilling, keep the bit cool with cutting oil.
Steel Spade Bit Set 6 Pc
Quick question regarding on/off function of the board.
I have the hifi 2.0 version that simply has the switch wired to mute and grd. This is great for preventing the pop bump for on/off (unplugging power)
However I like the idea of using the stz (standby) function instead as it uses less power for when I leave the power connected, and want the unit to go standby.
Do I just simply rewire the switch to ground the stz instead of the mute?
I have the hifi 2.0 version that simply has the switch wired to mute and grd. This is great for preventing the pop bump for on/off (unplugging power)
However I like the idea of using the stz (standby) function instead as it uses less power for when I leave the power connected, and want the unit to go standby.
Do I just simply rewire the switch to ground the stz instead of the mute?
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Well, the Q5 is an Audi automobile - but maybe he's not referring to that.
It's also an ST based digital amp from SMSL - it's not a 3116 based amp. It's available on Amazon, for one place:
http://www.amazon.com/SMSL-Optical-Coaxial-Digital-Amplifier/dp/B00NINSV20
It accepts direct digital input, unlike the 3116 amps that only accept analog input. So this is a bit of an apples and oranges comparison, it appears.
Also, at the above Amazon link, it has poor reviews - rated 1.8 out of 5 stars.
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Yikes,
I was reading another review on Amazon Amazon Review that looked really good, albeit only one review to show, and almost bought that Q5 unit locally, but just learned they are sold out on the Q5.
Now, I am wondering...
There's also a FX-AUDIO D802, or just go back to the TPA3116D2....
I was reading another review on Amazon Amazon Review that looked really good, albeit only one review to show, and almost bought that Q5 unit locally, but just learned they are sold out on the Q5.
Now, I am wondering...
There's also a FX-AUDIO D802, or just go back to the TPA3116D2....
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There are lots of choices in digital amps and they are reasonably priced enough that one could try them all out and use the best. Just takes some time.
Hi Les H, is that SMSL SA-60 containing also the snubber mod among the bootstrap one you mentioned before? is there any chance of bypassing that digitally controlled volume and use that potentiometer as an ordinary analog one? I read the review over at amazon and it was mentioned that it sounds a little too "bright", maybe it is set for too much gain and need to change the value of the gain resistors? it would be nice to hear someone that swapped the aircore inductors for more common ferrite ones used in such aplications and how did that impact on sound quality; thanks
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Most of the reviews are related to functionality like DTS, Dolby or random sparks which is very common to all amps of this kind. Nobody made a proper comment on its sound quality.
If they dont spark we mod them to spark better. Right channel seems to work all the time for most reviewers, funny they don't mention SQ, who needs left channel anyway😛
Anyone tried this?
SER8052-103MEB Coilcraft | Mouser
They are so tinny... about the size of the Sure board inductors.
6.32 A and Maximum DC Resistance: 14.33 mOhms
SER8052-103MEB Coilcraft | Mouser
They are so tinny... about the size of the Sure board inductors.
6.32 A and Maximum DC Resistance: 14.33 mOhms
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I haven't disassembled the unit yet to check all the details. I would not call the amp bright (if it's not bright with the B&W Nautilus it is not bright at all). I'd call it "under-powered" - which of course if the nature of the beast as the 3116 is a relatively low powered amp with 8 ohm speakers.
I think the "volume control" is not an analog volume control at all but rather a rotating switch that sends input to the volume control chip. But I do plan to look at it more closely.
I haven't tried replacing the air inductors with solid core.
My plan is to obtain some of the better 3116 boards (probably the Sure) and modify that as needed for a comparison to the SMSL.
At the moment I have an Audiophonics TA2022 amp. I like it. Because of your posts about the SA60 and the good reviews of the SA60 elsewhere, I am considering buying a SA60 amp. Do you think it will be a major upgrade? Or, do you think the differences between the two are minor?
Stay away. Look at the saturation current - 30% inductance drop at 3.10A.
http://www.mouser.com/ds/2/597/ser80xx-253338.pdf
When you're picking inductors, find the inductance versus current plot and make sure that the inductance curve is flat from 0A to the highest current you'd expect the amp to be putting out - eg for 18V power and a 4 ohm load, 4.5A.
10% Isat drop at peak current is probably acceptable but it's naturally better to have it flat to above the peak current output.
For those wondering. On a BLT single supply amp like the TPA3116, peak current is just supply voltage divided with load impedance. Although that overshoot the actual peak current slightly because it ignores switching losses, it's a good number for design and component choice purposes.
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