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High-end chipamp build project

Posted 24th January 2013 at 08:21 AM by abraxalito
Updated 15th February 2013 at 06:12 AM by abraxalito

Go here : Possibly the most frugal high-end sounding amp?

If you have comments, feedback, critique or improvements and don't want to put it on that thread, feel free to leave it in the comments here.

Here are the first measurements - the Nitro amp being fed by the Ozone DAC with a six-tone multiple, peak digital level -20dB. Peak output power around 100mW in an 8R speaker (connected for this test). It looks from this that the datasheet is a little pessimistic on THD, though here I'm measuring the TDA8566, not the 8561. No measurement graphs are presented in the 8566 DS and the 8561 only has plots for 2R and 4R loads, not 8R.

Schematic now added. BOM here : https://docs.google.com/spreadsheet/...Hc&usp=sharing

Additional schematic showing how to use TDA8566Q in place of TDA8561Q as the latter isn't available from Mouser. Mouser only has fewer than 300 TDA8566Q in stock so best to get in quick - I doubt they'll be getting more as this chip is going obsolete. The pins shown unconnected in the mod schematic aren't unconnected - it means they're connected the same way as for the TDA8561Q.

Posted in Power chip amps

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Going back to the power supply and capacitor issue, it helps to model a classic class AB amplifier, I've used Bob Cordell's high performance power amp Spice models posted on threads here to explore this, they're accurate enough to see something meaningful.

Try hitting the input with a maximum amplitude 20kHz sine, and replacing the "perfect" voltage rails with some real power supply parts, and watch the distortion go through the roof! You will be able to see the damage done in the output stage's crossover region, and the glitching of the rails at this point. So, the trick is to get the parasitics down sufficiently so that the rail twitching effectively becomes insignificant ...

Frank

Posted 10th April 2013 at 02:46 AM by fas42 fas42 is offline

About the Teo cables piece - yes its interesting that although the cables had a very positive effect there's a complete lack of curiosity to uncover why this might be. Even Mr Teo himself doesn't have a story which works for me for his cables - when I mentioned this to him (on WBF) it seemed very clear to me he wasn't interested to offer one. So the smoke and mirrors continues - nobody wants the game to end, should that happen then the stratospheric margins commanded for cables will evaporate like the morning mist...

Posted 10th April 2013 at 04:15 AM by abraxalito abraxalito is offline

Can't shake off that cap addiction, I see, let's hope there's no cold turkey moment coming ... ;)

Remember Terry's parallel plate setup: [url]https://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size-102.html#post3154705[/url] and [url]https://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size-121.html#post3166558[/url]. I did a variation on this many years ago and was happy with what it achieved ...

Frank

Posted 16th April 2013 at 10:48 AM by fas42 fas42 is offline

	Yes I do remember that as it was inspirational to me at the time. But its only 2D and I prefer 3D solutions myself. There must be a reason God gave us 3 dimensions.... The cold turkey moment hit a few days ago with some very cheap 3300uF/16V caps from taobao (0.18rmb each) which exploded!
	Posted 17th April 2013 at 04:29 AM by abraxalito Updated 17th April 2013 at 04:45 AM by abraxalito

	Looks like Soulution have been listening to what their products actually sound like too, :D : [URL="https://www.whatsbestforum.com/showthread.php?10466-Soulution-701-monoblocks-and-711-stereo-amplifier"]Soulution 701 monoblocks and 711 stereo amplifier[/URL]
	Posted 7th May 2013 at 12:52 AM by fas42

	Where's the evidence they care about the sound? The website is pure FFT koolaid from what I can see. Cyril Hammer being quoted on the WBF thread is talking BS about amplifier propagation delay, doesn't hold out much hope he has a clue about amp design, at least not ones with feedback.
	Posted 24th May 2013 at 07:53 AM by abraxalito Updated 24th May 2013 at 07:58 AM by abraxalito

I drew a pcb for this if anyone is interested. THought I could post it, but apparently pics cannot be added to this section.

Posted 2nd June 2013 at 01:24 PM by buzzforb
If you email the pic to me I'll include it in an edit to the main post.

Posted 3rd June 2013 at 03:24 AM by abraxalito
You're baaaaack ... :D, ;)

Frank

Posted 2nd July 2013 at 04:00 AM by fas42

	In status only, not in practice. On the so called 'offending' thread there were various technical posts I made which had none of the 'offensive' language which was the pretext for my banning. So I've asked what happened to them - so far, just tumbleweeds Incidentally I see Mr Basspig is freely sharing his misunderstandings about amplifier output impedance
	Posted 2nd July 2013 at 04:37 AM by abraxalito Updated 2nd July 2013 at 07:06 AM by abraxalito

Follow up to my just previous comment. I never did get a reply to the question to Steve Williams about what happened to my posts. But I did get a ban. Not sure why, no reason was given.

A week or so ago I got a friend request from Ken Newton so I attempted to log in to WBF to accept that - but my password didn't work. So I requested a new one. All was fine and I was able to accept that, but shortly after I got a PM from Steve Williams with the title 'I see you are back'. It just had one sentence in it - that I'd better adhere to the TOS or my prediction about getting a ban would come true. I figured that as I had no intention of posting anything I'd be fine. But I was wrong - my prophecy did come true. I got a PM from LL21 (Lloyd) this morning and found my password had been reset, so requested a new one. After typing the reply to Lloyd's PM, on hitting 'send' I got the 'you are banned forever' screen so presumably he won't receive that PM.

Posted 12th September 2013 at 11:44 PM by abraxalito abraxalito is offline

hows sound compare to TPA3116 ?

Posted 15th August 2015 at 11:15 AM by oxoxbyx
Better, particularly in the bass. Doesn't go quite as loud though.

Posted 16th August 2015 at 11:26 PM by abraxalito

	for power supply better using switching or transformer ? I will check on alie express I hope found this chip. TDA8561Q is better than TDA8566Q right? i hope this one not fake Free Delivery.TDA8561Q-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com \| Alibaba Group
	Posted 17th August 2015 at 06:26 AM by oxoxbyx

	No, I haven't noticed that TDA8561 beats TDA8566, I didn't notice a difference between them. For power supply using a transformer is simpler, if you use a switcher you'll need some filtering (both normal mode and common mode) to get the best sound. I'd use a regulator if you use a transformer, like LM338.
	Posted 17th August 2015 at 10:33 AM by abraxalito

for this application 2 amper transformer is enough?

Posted 17th August 2015 at 02:16 PM by oxoxbyx

	It might work depending on if you're using an LM338. If not then probably not quite enough current. Short-term peaks get handled by the reservoir capacitor but if you use an unreg supply the droop on load will be significant. If you go over voltage the chip will mute but not be destroyed.
	Posted 17th August 2015 at 11:40 PM by abraxalito

So does it run balanced outputs in the configuration you have?

Posted 22nd August 2015 at 12:45 AM by Destroyer OS

	Sure - all these TDA-series car radio chips have balanced (or bridged) outputs to get sufficient output power from the nominally 14V rail.
	Posted 22nd August 2015 at 11:10 PM by abraxalito

	Interesting, perhaps I should venture into some other chips than the TDA7297. I'm somewhat under the impression that the balanced has benefits not seen otherwise. The reputation of some qualities they seem to have is talked about much, ever. At the far spectrum I'm reading about Ampzilla versions, also balanced.
	Posted 26th August 2015 at 03:46 AM by Destroyer OS

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	I drew a pcb for this if anyone is interested. THought I could post it, but apparently pics cannot be added to this section.
	Posted 2nd June 2013 at 01:24 PM by buzzforb

	If you email the pic to me I'll include it in an edit to the main post.
	Posted 3rd June 2013 at 03:24 AM by abraxalito

	You're baaaaack ... :D, ;) Frank
	Posted 2nd July 2013 at 04:00 AM by fas42

	hows sound compare to TPA3116 ?
	Posted 15th August 2015 at 11:15 AM by oxoxbyx

	Better, particularly in the bass. Doesn't go quite as loud though.
	Posted 16th August 2015 at 11:26 PM by abraxalito

	for this application 2 amper transformer is enough?
	Posted 17th August 2015 at 02:16 PM by oxoxbyx

	So does it run balanced outputs in the configuration you have?
	Posted 22nd August 2015 at 12:45 AM by Destroyer OS