Don't forget C317/318/319 320 on the main PCB are used to provide a low impedance path to audio... more important at hf when the open loop gain of the amp is falling.
Muting transistor... never had any (serious) kit that used that arrangement so can't say one way or the other. In theory they are "non existant" when off, although some may argue that a varying signal might alter the junction capacitance etc thereby affecting the signal, particularly if fed from a high source impedance... just remove as a test to see
Diode bridge is fine... I see it has a snubber network on the secondary winding. That's good... I also like to add a small (0.047uf approx) across each individual diode too in the bridge. Diodes cause something caused "commutation" noise as they come in and out of conduction... I first came across that on a small Hitachi radio that buzzed on audio on FM... a single cap across the transformer secondary stopped it completely.
Opamp decoupling... well the correct way is not to feed supply variations into the grounds, however you are stuck with the PCB layout as is so. I would add a small 0.1uf or so directly across supply pins, not supply to ground.
No experience of the Chinese stuff... you hear good (and a lot of bad too) reports... dunno... I think you would like something you could tweak... perhaps something off EBAY as starter to have a play around with...
Speakers make a huge difference... for years I used Celestion SL6's then SL100's however a few years back decided on a major upgrade and settled on B&W703's
View the 703 at Bowers & Wilkins - The World's leading Hi Fi Brand
Muting transistor... never had any (serious) kit that used that arrangement so can't say one way or the other. In theory they are "non existant" when off, although some may argue that a varying signal might alter the junction capacitance etc thereby affecting the signal, particularly if fed from a high source impedance... just remove as a test to see
Diode bridge is fine... I see it has a snubber network on the secondary winding. That's good... I also like to add a small (0.047uf approx) across each individual diode too in the bridge. Diodes cause something caused "commutation" noise as they come in and out of conduction... I first came across that on a small Hitachi radio that buzzed on audio on FM... a single cap across the transformer secondary stopped it completely.
Opamp decoupling... well the correct way is not to feed supply variations into the grounds, however you are stuck with the PCB layout as is so. I would add a small 0.1uf or so directly across supply pins, not supply to ground.
No experience of the Chinese stuff... you hear good (and a lot of bad too) reports... dunno... I think you would like something you could tweak... perhaps something off EBAY as starter to have a play around with...
Speakers make a huge difference... for years I used Celestion SL6's then SL100's however a few years back decided on a major upgrade and settled on B&W703's
View the 703 at Bowers & Wilkins - The World's leading Hi Fi Brand
You know what? I think I won't touch the Pioneer. It's good as it is (listening to the Jayhawks' "Hollywood Town Hall" right now)...and I voiced my DAC with it. if I want something different, I'll buy the Yulong amp.Don't forget C317/318/319 320 on the main PCB are used to provide a low impedance path to audio... more important at hf when the open loop gain of the amp is falling.
Muting transistor... never had any (serious) kit that used that arrangement so can't say one way or the other. In theory they are "non existant" when off, although some may argue that a varying signal might alter the junction capacitance etc thereby affecting the signal, particularly if fed from a high source impedance... just remove as a test to see
Yeah, I knew about commutation noise in diode bridges. I used to bypass them too.
Good to know, thanks
I've had good luck so far
I know it all too well... but I really enjoy cheap speakers too, when they're genuine sounding (like my Monitor 30's). I have no prejudices of sorts...not anymore. Once I would only listen to speakers at least 1000€ per pairSpeakers make a huge difference... for years I used Celestion SL6's then SL100's however a few years back decided on a major upgrade and settled on B&W703's
I'm ashamedOhhh.... you mean you won't even try a different opamp lol
If you are happy keep it as it is
Alright...gonna make the parts order now
That's more like it... I think I would just try the opamp first... then listen
Also... make up a test lamp (100watt filament bulb) that you can put in series with the mains to the amp. Just to try each time you mod it... just in case anything untoward has happened, solder blob, short etc... it saves the amp self destructing. Test with that with no speakers connected, then remove the bulb before listening... if you leave it in the amp can't draw enough current and may behave unpredictably.
Also measure the DC voltage present at the speaker outputs before you reconnect them... always be sure.
Also... make up a test lamp (100watt filament bulb) that you can put in series with the mains to the amp. Just to try each time you mod it... just in case anything untoward has happened, solder blob, short etc... it saves the amp self destructing. Test with that with no speakers connected, then remove the bulb before listening... if you leave it in the amp can't draw enough current and may behave unpredictably.
Also measure the DC voltage present at the speaker outputs before you reconnect them... always be sure.
Thanks...but I don't think I'll follow the lamp suggestion. Usually I'm pretty precise in soldering...instead I'll definitely measure DC voltage across the speakers after any opamp change, just as the good praxis commends.
Made the order, BTW. For the Muse bypass caps, I will choose between 100nF 250V Wima MKS4, and 150nF 100V Wima MKM2. I'm curious about the latter...
Made the order, BTW. For the Muse bypass caps, I will choose between 100nF 250V Wima MKS4, and 150nF 100V Wima MKM2. I'm curious about the latter...
Or perhaps I'd buy new speakers first
I like these:
http://www.systemfidelity.com/pics/SF3010 wengue pair.jpg
Small, closed (no bass reflex)... should meet my requirements
And if not enough bass... well, add a small subwoofer, why not. But I think they may have enough bass for me.
if you look for sealed enclosure speakers, why don't you try Canton speakers. they are really good.
What model? I admit I don't know Canton speakers much, aside from this GLE series I've been interested about (and heard at a store).
Well... finally I got to try the Audioquest King Cobra! It was aboouuut tiiimeee...
It seems very rigorous sounding... more full bodied than the VDH The Bay C5, with more "blackness". Treble is less rounded. It already looks very clear sounding, too...a very neutral and transparent cable.
Edit: with very well defined bass and treble... I'm loving this cable.
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Tip... fit 4558's or similar and listen for a week... then whatever you replace with will be wonderfullllllllllllllllllllllllllllll
No, but... this UPC4570 really sounds good. I think it must be identical to the MC33078 (compare the specs).
I bet your DAC sounded "really good" too before you swapped opamps and made it better.
Get 'em changed lol...
It sure did...but now it's better (more rigorous and transparent). The LT1364 sure isn't rubbish by a long shot!
And your amp sounds good... but you might make that better too
Turkey soup awaits...
lol. this will never stop. I am in the same shoes hehehehehe I always look to improve staff too.
Tip... fit 4558's or similar and listen for a week... then whatever you replace with will be wonderfullllllllllllllllllllllllllllll
I'm one to talk... my Sony Minidisc... lol
OPA1612 maybe perhaps.... ish... and those muting transistors...
My excuse... I don't class this as "serious" kit... but it's very good as is... maybe we can make it better...
