Great video. 160 watts will be pretty loud. Especially if you have proper speaker cabinets to drive. I used to have a receiver that was only 100x 2 driving 2 cabinets with a tweeter, mid and woofer, and it shook my apartment. I think the class A you built was 20 watts per channel or close to it which is fine for bookshelf speakers, but this amp should really crank. Thanks for the tip on inverting a probe to get A-B so I can measure current across a resistor.

@KissAnalog

2 жыл бұрын

Thanks Tron! I did end up getting about 30 Watts from that Class A, but I think it most likely went A/B in the higher wattage. It is a hot beast;) I'm glad that worked out, I will do a video on probes and how to use them on the scope. I also picked up some low cost scope probes to review;)

@guidolonghi869

2 жыл бұрын

@@KissAnalog Hi, I bought an xh-m258 and after seeing your videos I decided to change the 24va toroid and I bought a 35va dual 500VA toroidal that I just connected but something is not working because the TDAs heat up but I have no audio and measuring on the speaker terminals I have 7.5vc on one side and 9vc on the other and trying to lower the volume of the source, the output voltage on the speakers does not decrease. From the video I understood that the xh-m258 could be powered with double TDA8954TH with a dual 35v. Did I get it wrong or is something escaping me? Thank you in advance.

Great work Eddie! Awesome video!

@KissAnalog

2 жыл бұрын

Thank you Brendan! I appreciate you!

That's a really nice oscilloscope. Added to my list of things to buy.

Hi Eddie, Thank you for the awesome video and awesome explanation.

@KissAnalog

2 жыл бұрын

Glad you enjoyed it! I appreciate you!

Hi Eddie! I watch most of you videos but I don't comment often. I like when you review books, teach us about power supplies and audio. I was wondering if you could do a video in the future showing different types of pcb power conectors, connections and any useful parts used in your designs. Thanks for reading (hopefully) and have a great day!

@KissAnalog

2 жыл бұрын

Thanks for this great feedback! That's a great idea! Thank you!

Thanks Eddie. Old technology, you can get 400 watts out of the Purifi and over 1k out of the ICE modules without external cooling. I'm running the ICE modules in my system now, the sound is great and since I never utilize 1kW the distortion stays very low, I figure once you get above ~1% you start to hear it. My amps run so cool you can hold your finger on the components. I'm really sold on class D, it would be neat to do an AB test with the class A you built and my class D with the tube buffer stage, I wonder what your friend would think then? The trick is to set up the class D and its buffer together then do the FFT's and bode plots. This way you can really contour the sound to your liking. I think it's what you like, I like detail, resolution, soundstage and dynamics. The 6922 tube is great for that and so is class D. I just rebuilt a Fisher 500c tube amp from the 60's and it sounds pretty darn good at 32watts of tube power but doesn't compare to the class D amps. I can't imagine you can get real dynamic range out of a 25 or 30W class A amp, it's probably okay but if you play Holts The Planets into low or mid efficiency speakers doing an AB comparison I think it would show the difference in dynamics. Most times when I hear class A systems people are showing off it's with singers or guitars in small ensembles that don't require broad dynamics. Here's an idea, why don't you do some testing comparing class A and D, you should see some differences when you push the input signal to simulate high dynamic range music. I think the Pico would show it up nicely. What's the noise floor on the class A you built?

@KissAnalog

2 жыл бұрын

Thanks for this great feedback! I have looked at the ICE modules, and have been intrigued;) I'll take another look. I want to reverse engineer one;) I also like it when I can keep my finger on parts without the heat making me pull away! My plan is to build this Class D and give it to my friend to do A/B comparison with his 30W Class A. I agree, the Class D should have a lot more dynamic power. I always wonder about the 'sound' part of the amp. My feeling is that a great amp should be linear and not have a sound of its own. But, then I know they do - there's psychoacoustics that I think are not even perfectly understood. So, that's why I'm so interested in this comparison. I think it goes far past THD, or the noise aspect, but maybe the THD (to a limit) does relate to the amps ability to represent the signal maintaining the original signal quality. I'm very interested in the multi-tone test. I'll have to try that and see what it shows;)

@mosfet500

2 жыл бұрын

@@KissAnalog I'm interested too. I remember when you did the class A and there was all that second harmonic distortion. I think class D can be a little antiseptic but it sounds great with a tube buffer. I agree specs don't mean you'll like the sound. Should be fun. Hope you're feeling better!

Hi Eddie, Now that you've been playing with the PicoScope for a while, which scope would you want as a second scope next to a siglent: PicoScope, MicSig, or GW Instek? Cheers Mark

@KissAnalog

2 жыл бұрын

Great question! And the answer is easy - Pico for sure;) This model is more expensive but check it out;) amzn.to/3sbFM9h

Hi, I bought an xh-m258 and after seeing your videos I decided to change the 24va toroid and I bought a 35va dual 500VA toroidal that I just connected but something is not working because the TDAs heat up but I have no audio and measuring on the speaker terminals I have 7.5vc on one side and 9vc on the other and trying to lower the volume of the source, the output voltage on the speakers does not decrease. From the video I understood that the xh-m258 could be powered with double TDA8954TH with a dual 35v. Did I get it wrong or is something escaping me? Thank you in advance.

Great video. I wonder how this amp would compare to the rather expensive Hypex modules. I'm just about to buy a bunch of class D amp boards for a fully active 3-way system but I don't quite have the budget to go fully Hypex N-Core so I'm looking for cheaper alternatives. Cheers.

@KissAnalog

2 жыл бұрын

Thanks for the great question! I think I need to pick up a Hypex board to see how they perform. But, I think this one would do well.

@deanedgx

2 жыл бұрын

@@KissAnalog thanks.

If I am going to use a 24 0 24 15Amp traditional transformer with this board, then what will be the outcome(Watt/RMS) for each channel at 8Ohm load? Another point is whether a 24 0 24 15Amp traditional transformer will destroy the board or not?

If I use best quality transformer ( 24-0-24 & 20 amphere) then what is the maximum watts I can get from it?

Hi Eddie.I am on my second board.About two years now in this project.Tried many power supplies.Always the same problem with two new amp boards.Every thing is fine on the bench and power testing.But when i connect the speakers at high volume it starts to cut out.No matter if it is 4 ohm and 8 ohm.For now i am running 1kv torroidal 24-0-24v ac.Do you think some kind of protection,because i know my speakers can do a lot more.Thank you.❤

@KissAnalog

2 ай бұрын

Thanks for the great question! Just to be clear - when you say cut out - it means the sound turns off? It sounds like over temp. Does it come back in a minute or so after it cools down? Or, does it come back immediately after the volume is turned down? In that case it is over current.

@amin125ccm

2 ай бұрын

@@KissAnalog Thanks for fast reply.If i turn down volume a bit ,it goes back to normal.When it cuts out it lasts about half second.Chip is not hot at all.Starting to wonder if board is designed bad.At around 130w it starts to cut out if I back it down to 120w ,no problem.Really low power for what is it reated.

Well I really don't play with class "D" much as I really don't like how they sound, but I would think 500 AV is more then enough. But I'm not sure if that would be the best way to go? I think I would look at a switching power supply seeing how you're really aren't chasing low THD, and it seems they have thought of that seeing the ripple rejection the TDA8954 has.

@KissAnalog

2 жыл бұрын

Thanks for the great feedback! I think you are on target;)

Does it have power-on/off “pop” problem like many TPA3116 boards?

@KissAnalog

2 жыл бұрын

Great Question! I don't hear one and the data sheet does say that it has protection against this - which seems to work well. Probably a delay before it allows the output to change.

That's a really crappy looking spectrum! The switching frequency spurs could be further down, and what's the story with those spurs in the audio band? I won't be running out to buy this amplifier... The picoscope looks pretty nice. Might pick one up.

@KissAnalog

2 жыл бұрын

Good eye;) This might have been my fault as I was looking at the THD just to see when the waveform started to get distorted. I've looked at the spectrum before and didn't see this, so it might have been due to a setup issue. I'll look into it.

@questionmark9684

2 жыл бұрын

@@KissAnalog hi Eddie, please let us know! Cheers Mark

I 've read that it can be powered at maximum with dual 28-0-28 and as 28 * 1.41 = 39.4v after rectification this is close to 41v of the TDA8954TH is my guess true? Thanks to anyone who wants to share their ideas or experiences I hope even if the post is not very recent!

@KissAnalog

2 жыл бұрын

Thanks for the question! Yes it looks like you have it right:)

Why don't you use the Chinese power supplies?

get a 10 amp +-40v switching power supply ... it can't make the carrier noise any worse.

@KissAnalog

2 жыл бұрын

Thanks for the feedback. That's not a bad idea;) I do plan on designing a project from power supply to amp that is all switching. I thought I'd use a transformer on this for a more direct comparison to the Class A that my friend is using. Do you have a particular make of switcher that you would recommend?

@davidkclayton

2 жыл бұрын

@@KissAnalog hey yeah I understand the urge to use Transformers that you got lying around I have some too, however for around 40 bucks you can't go wrong if you can wait for China to deliver. There's some good choices out there which I've used in the past just do a search on eBay for "800w ±40v llc soft switching power supply" and take your pick. As for brands that's for rich folks I'm an experimenter having said that you're most likely have to modify the bridge rectifier and capacitor circuit on the line side as they are 220vac, just rewire it into doubbler like you would in a computer power supply. You will need new caps but I'm sure you have those lying around.

Class-D amps using GaN technology. Hope this happens (or has it?)!

@KissAnalog

2 жыл бұрын

Great question! Yes it has happened, and I actually tested a couple on this channel. kzread.info/dash/bejne/oqCKmrVtltTWj7Q.html

CAN SOMEONE HELP WITH BUILDING MY OWN AMP?

@KissAnalog

Жыл бұрын

What would you like to see in this video?

This ic is obsolete sir. It was a great ic

@KissAnalog

2 жыл бұрын

Yes it is - thank you! I did a video on this; kzread.info/dash/bejne/oo6gsauMiNa-o5c.html

@bamrahbabbu

2 жыл бұрын

@@KissAnalog i want to create a class d amp about 200+ 200 watts rms at 4 ohm. Can you suggest the same ic like 8954th? We made ab class with 7294ic but from last one year the price of this ic is going high. Help me to decide

transformer ampire

@KissAnalog

Жыл бұрын

Are you voting for a transformer power supply?