Pete - no I'm not saying that. To me it doesn't matter if the coupling cap is a film one or not. But the trafo performs best when driven by a low impedance at the lowest audio frequencies and 10uF coupling gives too high an impedance at LF. Adding another cap in series with the 10uF (if that's what you have) will only raise the LF impedance, not lower it.
So if your DAC or pre has only 10uF output coupling, increase that cap to 47uF for best results.
Is that any clearer now?
So if your DAC or pre has only 10uF output coupling, increase that cap to 47uF for best results.
Is that any clearer now?
Yes, thanks Richard. I can temporarily parallel an electrolytic with the 10uF film and see what it sounds like.
I have ordered a pair of those mono amplifiers two or three months back, just want to give a short feedback now I lived quite a while with them.
Short version: sounds terrific, a real steal.
Little longer version: very well balanced, neutral in a very positive way with a slightly warmish feel. Particularly the high frequency is not like the typical class d sound, very nice, never harsh. And maybe because of the double mono they also produce a very wide stereo image with quite some depth.
My Audio buddy Ernst told me that he knows a guy who sold his 5k€ Golde Note amp after listening to those little buggers. No surprise for me.
So congrats and thanks to Richard, very happy camper here.
And now I am very intrigued to try one of his dacs...
Short version: sounds terrific, a real steal.
Little longer version: very well balanced, neutral in a very positive way with a slightly warmish feel. Particularly the high frequency is not like the typical class d sound, very nice, never harsh. And maybe because of the double mono they also produce a very wide stereo image with quite some depth.
My Audio buddy Ernst told me that he knows a guy who sold his 5k€ Golde Note amp after listening to those little buggers. No surprise for me.
So congrats and thanks to Richard, very happy camper here.
And now I am very intrigued to try one of his dacs...
H
HAYK
If you want ultra clean sound from this chip try the ABD mod.
https://www.diyaudio.com/community/threads/convert-your-class-d-into-abd-modulation.396664/
post 2. You only need to add a 2W220ohm resistor.
Just a single smps for now. I tried a Sigma11 regulated supply, but surprisingly I like the smps more, it is snappier and more dynamic, although maybe a little less forgiving. Planning to go with double mono smps, they are cheap as chips nowadays.
Looks interesting with those 220r, the theory behind it is way over my head though. So far I'm very pleased with the sound and don't want to mess them up. Maybe Richard wants to give it a try.
Btw, I like it more than my F5 build, which I'll sell. The F5 has its merits, but everything considered Richards amps sound better to my ears.
Hi Richard,
I use a balanced DAC out and would really like to have a balanced input to your amp. The amp is SE, of course, yet it has transformer input and this make me think, it could be configurated for a balanced input. Any chance to make this work?
Cheers, Ernst
I use a balanced DAC out and would really like to have a balanced input to your amp. The amp is SE, of course, yet it has transformer input and this make me think, it could be configurated for a balanced input. Any chance to make this work?
Cheers, Ernst
Hi Ernst,
You are quite right - given that the amp has a trafo input, it really doesn't care if the source is balanced or unbalanced. To run balanced you'll just need to check the GND lift resistor is removed. That's R21 (10R) which I fit by default as most drive these amps SE.
@Jogi - I have given consideration to @HAYK's mods but the extra distortion that R introduces (see the thread that @HAYK has started to introduce his mod) has so far put me off. Like you I also am very happy with how these amps sound in stock form.
You are quite right - given that the amp has a trafo input, it really doesn't care if the source is balanced or unbalanced. To run balanced you'll just need to check the GND lift resistor is removed. That's R21 (10R) which I fit by default as most drive these amps SE.
@Jogi - I have given consideration to @HAYK's mods but the extra distortion that R introduces (see the thread that @HAYK has started to introduce his mod) has so far put me off. Like you I also am very happy with how these amps sound in stock form.
Hi Richard, I wouldn't have considered it that simple 🙂 So I just have to uncheck the ground lift resistor and probably put the XLR plug groundpin to the amps ground, right? Cheers, Ernst
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Yes, without a common GND between your source and the amp you might get hum so it is advisable to link the amp's GND to your source GND. Which normally would be accomplished by the XLR's pin1 when balanced mode is being used.
H
HAYK
The distortion measured by B.Bunny was totally erroneous although he admitted to be wrong, he succeeded in vomiting in the soup.
post 58 https://www.diyaudio.com/community/threads/convert-your-class-d-into-abd-modulation.396664/page-3
Richard, I'll be trying the resistor addition within the next two days so I let you know what I hear. Is it possible that the measured distortion is introduced in the frequency range way beyond normal human hearing?
Cheers, Pete
So here's how I'll be testing the SQ of HAYK's resistor inclusion (not a scope-guy, sorry). Reading through the following document ( https://www.eetimes.com/understanding-output-filters-for-class-d-amplifiers/) I'll reference the three attached illustrations from that document showing a normal LC filtering (currently on our Class D amps), what I think is the mod HAYK is proposing with a single resistor (except the illustration uses a resistor for each cap's ground feed) and finally the use of additional caps to reduce the upper, upper frequency noise induced by the use of the resistor(s). My altered drawing of the third scenario, for use with the single resistor proposed by HAYK, is also shown (I think I have it correct). I'm just going to have to calculate what C3 would be (C1 & C2 are the normal 0.68uF caps in Richard's circuit).
Cheers, Pete
Cheers, Pete
Attachments
dunai2000....so far I can't detect anything detrimental by adding just the resistor (Class ABD) or adding the cap across the resistor (my drawing; Class ABD + 10uF cap). It's hard to tell whether anything positive has occurred. I'll be receiving another of Richard's kits this week and will build it up with stock components then put it in its own enclosure so I can quickly switch between stock & modified amps. So far the only thing definite I can say is what preamp you choose to input the signal has more impact on what you hear. Obviously one's DAC will play a role as well but I'm only rolling through preamps.
Cheers, Pete
Cheers, Pete
H
HAYK
Thank you for trying the ABD mod. If you don't get enhancement because there is a bottleneck in the circuit. Maybe the input transformer. The two music files bellow 99% of amps including the Wolverin cannot reproduce clean sound. When converted to ABD, it does with celestial voice.