I regard it as overcompensated. That makes it particularly suited to low-fatigue music replay. That also makes it a lot less suited to any other use.
The 100u caps have helped the resolution of high pitches slightly. Its just the same hack you'd use on an overcomp STK amplifier from the 70's and with exactly the same sound. I did compare it head to head. Its the same--not as good as high end, much easier to use than high end, and still better than everything at Black Box retail. No matter if 1978 or 2015, the caveat is the same--it isn't very interesting to use for tv/movie sound. That's because it is relaxed, non-shouty and won't artificially highlight the voice band.
The super-high gain of this chip will do 5 things:
It will be super easy to get enough blast from your phone.
It will relax the amp so it won't cause the need of an eq.
It will have bigger dynamics (unpleasant for TV commercials)
It will disable some of the power noise rejection capacity, thereby causing the need of better power.
It will effectively slow down the amp for a more old-fashioned sort of character which is a rarity in Class D amplifiers although sounds exactly like '69 JLH or '78 STK amplifiers, resulting in similar applications.
That is the typical behavior of a high-gain linear amplifier. However, it is very surprising for a Class D amplifier to behave like and sound exactly like a linear amplifier.
It is already relaxed, therefore, I suggest that we avoid under-volting it down to 12vdc. It may be important to maintain the voltage range at 18vdc~23.3vdc. . . prior to judging its imaging performance. Other techniques to reduce the shout/instability of typical commonplace amplifiers, are to be avoided--don't give it more xanax because it already took two (previous build techniques may backfire).
To make it more nervous, which would only make this one more normal, you'd have to reduce the gain. I have not researched how to do that for this chip. I didn't change it because the job I needed done, background music for my office, is one of the things this amp can do well in out-of-the-box condition. There was no need to remove that capacity.
Last edited:
Any solid conductor big enough to fit the vias. Add it. Then solder the wires to it. Use flux.
Or, flux the vias, add solder to the vias, add more flux to the vias, flux the wires, add solder to the wires, flux the wires again, then bond the wires surface mount to the vias.
P.S.
If you get excess solder, such as a short/bridge, then flux it, heat it, and quickly tap the board inside the trash can. The excess solder, and probably the component or wire you were working on, will fly off and land inside the trash can. No more short. Or a desoldering iron can work, albeit more slowly.
P.P.S.
Gel flux is an easy to use formulation of petroleum jelly combined with rosin. Sooner or later, you're going to want some of that stuff.
Last edited:
It isn't very efficient and the board (its only heatsink) is credit card size, which is okay for room temp with a well vented enclosure.
Can you glue the board to the enclosure? A siliconized glue if thin and also securely fastened, may provide enough heat transfer to survive either a sealed enclosure or all-weather use, probably not both conditions simultaneously. Prospect: Make the board, aka heatsink, get bigger so the amp can survive a wider variety of conditions.
I cannot make a guarantee of that. However, this is the only Class D amplifier to have passed all of my tests without catching on fire. I made it do exactly as the datasheet claimed, and it did that easily, with at least some margin to spare. Quite honorable really.
In addition to taking a lot of abuse with grace, it did only one other thing spectacular; and, that is rather charming mid-fi sound just like a classic amp, yet surprisingly provided in a credit card size and slightly better efficiency.
For example, a real concert amp mandates a very pleasant character in all conditions so that it is never useless to crank it up loud. This is just like that, except credit card size instead of footlocker size, along with the expected difference in output power. Otherwise, it seems just the same. If you liked the sound at the concert, this does a little of that, and just like it.
If it is bolted to one specific speaker cab, then you might as well install a capacitor series to the woofer, specifically sized as small as possible without reducing what the woofer Can do, with the main point being to reduce the load on what the woofer cannot do (this a popular state-of-the-art subwoofer modification that actually works with any size woofer). You'll have to get the sizing just right (which isn't difficult). This loading reducement will increase the clean capacity of both the speaker and the amplifier by several means. For the woofer, it will cause progressive current drive, for slightly louder lowest notes (in a specific half-octave, that series cap will act just like a low-loss resistor). For the amplifier and tweeter, the decrease of waste loading will provide for decreased clipping. Although the change is minor, bear in mind that just 3db is the difference between this 30W amplifier versus a 60W amplifier. You'll probably only get about 2db out of this mod; however, that's still the difference between this 30W amplifier versus a 50W amplifier. The other point to reducing waste loading is amplifier efficiency as it pertains to heat. Your amplifier would still prefer to drive some cable, so be sure to keep added accessory capacitive filters at the speaker-end of the cable (not directly at the amplifier board). This tip won't help with a very big speaker; however, it will work bravely well with smaller speakers.
I tried that already. The 50W was a little overstatement. I got 43W. This was with a 5.25" woofer, and so your results could vary depending on the size of both your woofer and cabinet, so far as how much series capacitance is "just enough" to allow for un-hindered bass performance on the average track. Usefully, it did skim a few notes on some overdone tracks (that contained far too much bass boost pre-applied), thus I didn't have to dash to the volume knob frequently to stop a madly clipping amplifier. . . because it just didn't do that problem. Point: If the amplifier is bolted to a specific speaker, increase efficiency by reducing its notion of the audio band to only what the speaker can output.
So, with that mod, a maximum output power increase wasn't very effective; however, what was effective is that I could turn it up a third more without a blur. In that way, the increased headroom (by removing waste loading) was at least useful.
Last edited:
I was reading last night that 22 AWG wire can be used for speaker wires for lengths up to 3 feet with a 2 ohm load, 6 feet with 4 ohm, 9 feet with 6 ohm, 12 feet with 8 ohm.
I'm considering just soldering 22 AWG wire to the speaker outs on the PCB, since it's only a few inches to my speaker jacks.
Opinions on this?
I'm considering just soldering 22 AWG wire to the speaker outs on the PCB, since it's only a few inches to my speaker jacks.
Opinions on this?
For distances of *approximately* 8 inches and less, it should work even better than thick wire.
With a short thin wire, you're actually just approximating a long thick wire, which is normal use. No problem.
I'm very disappointed in what seems to be a very typical style for you when you post a "review" about some part or circuit: NO MEASUREMENTS! All you seem to be capable of is prose about the item in question, using words like "shouty" or "dull" or saying it sounds like "a 70's amp". What crap. Words are a dime a dozen, and "words" are what snake oil salesman use to convince people about some quality of their product that just cannot be captured by any measurement.
Now on the other hand if you start off with SOME MEASUREMENTS and then proceeded to give your "feelings" along with it, that would be a different matter altogether. But it seems that you never do that, Daniel.
Usually I would just ignore this stuff, but I see it over and over from you. Why should I believe anything you say? For all I know you could be deaf, dumb, and blind but with a really good imagination. Numbers go a long way to establish a basis upon which things can be compared. Qualitative "feelings" in which you talk about "tinkly" notes (that's a direct quote from above) are really not worth the electrons used to render them. Come on, rise above this crap.
sure, a full technical dissection would be great,
but Charlie's qualitative language, e.g. "very disappointed", "What crap", "you could be deaf, dumb, and blind", etc. is more disappointing than the OP's.
Thanks for your personal impressions of a piece of kit I haven't experienced myself, Daniel,
seemed clear enough you weren't claiming to come down the mountain with any stone tablets cut by God hisownself,
-Quard
but Charlie's qualitative language, e.g. "very disappointed", "What crap", "you could be deaf, dumb, and blind", etc. is more disappointing than the OP's.
Thanks for your personal impressions of a piece of kit I haven't experienced myself, Daniel,
seemed clear enough you weren't claiming to come down the mountain with any stone tablets cut by God hisownself,
-Quard
Last edited:
Most impressions on the forums here ARE subjective. Very little analysis - scientific or otherwise - is ever presented with the prose that so often accompanies the sound posters are trying to describe. You DON"T have to believe Daniel and are free to move on to the next post. BTW, I'm no big fan of subjective analysis either, but most people here are not electrical, or audio engineers, nor possess the equipment to provide critical analysis of what they're listening to. All they have is their ears. Hence the subjectivity of their opinions. Why pile so unfairly on to Daniel?
I'm also not a proponent of wholesale op-amp, capacitor, resistor, or any other device rolling. But it's done here liberally on just about every audio hardware topic/kit presented. If you're looking for hard facts or audio/listening opinions based on scientific evidence, than I suspect DIYAudio is not the place to hang out. If, on the other hand you don't mind reading someone's subjective opinion on a new amp, or set of speakers based on their listening critique than stay tuned.
A bit hyperbolic there, since early in the review is the comment that "I've proofed the datasheet claims, and they're true". It's not clear to me what "measurements" you'd need beyond http://www.techlabs.by/downloads/articles/Logitech_G51/TDA8932_2.pdf
I'd say the same about the IRS2092 based amps that I have, both "domestic" and Chinese . . . they all meet or exceed the performance shown on the IR data sheet and app notes. What more needs be said ? ? ?
Member
Joined 2009
Paid Member
The relevant measurement in relation to sound quality for this chip I have attached - its PSRR vs freq.
Guilt by association?
Attachments
[special=]%[/special]
I think it's human nature to get some external or third party confirmation on what we like and think sounds good. Sometimes, it can corroborate what we know to be true, but hearing it from someone else helps to reassure us.