I've done some closer inspection of the solder with a Bausch and Lomb loupe I've had since I was a geology student. There is a slight recess, but all look solid and not fractured. I'm inclined to leave it, unless my testing reveals disparate Iq values. Planning to hook up test leads across each source resistor one quad at a time to test. I think I have enough micro clips. Clip 5 at a time (10 clips), close the lid, let her warm up for an hour, then test voltage drop across each resistor. Should be a safe and effective way to do it. Since test leads will all be the same, test lead impedance shouldn't be an issue if the goal is to test relative matching. Turn off open the hood, hook to the next quad and repeat. Whole process should take about 4 + hrs. But honestly this amp sounds so bloody good I expect this might just be an exercise for fun! Oh and always wondered about the "M" . My intentions are to respect this circuit as designed down to replacement part number level.... ERX are obsolete so, yeah those of us in the know will hoard... Peace
Sounds like a fun experiment. Are you running a balanced preamp? I have heard good things about Dunlavy's speakers.
von Ah: Cool scene. I've always liked Gene Wilder. Netflix has a good short series out called Godless.
I drew up the PCB because I had a number of these caps floating around. Still have a handful left after populating two boards for some dual mono thing down the road. It is a parrot cage for a macaw. She is a great bird.
von Ah: Cool scene. I've always liked Gene Wilder. Netflix has a good short series out called Godless.
I drew up the PCB because I had a number of these caps floating around. Still have a handful left after populating two boards for some dual mono thing down the road. It is a parrot cage for a macaw. She is a great bird.
Yeah Von Ah, love that! Mike, Dunlavy... and the contemporary Duntech. Just incredible of you enjoy phase a time coherence. The X150.5 in Class A is sublime with this setup. Running balanced direct from PS Audio perfect wave MK II which has a gain control. Paul thinks it sounds better with a preamp so, I believe a balanced pre is my next purchase or build. I like Classe Cp-50, or Wayne's line stage balanced. I've got one line stage board need to order another for balanced. I think I'll remove the single ended input from the V150.5. Seems irrelevant....
I can't see the reason to remove it. The hot runs to the xlr and the RCA. The GND does the same. The neg to the XLR. There is no extra circuit caused by the RCA being there. Without the jumper it is just there.
This is all you have going on in your amp:
I am going to build a pair of Elsinore speakers. I believe Joe Rasmussen's speakers share some similar characteristics to the Dunlavy speakers. He has mentioned Dunlavy a few times. The BA2018 is a good board. It has nice imaging. It will impart a small amount of flavor to the sound but in a nice way. There was some recent talk about a balanced BA2018 wiring etc in the main thread. Worth a look
This is all you have going on in your amp:
I am going to build a pair of Elsinore speakers. I believe Joe Rasmussen's speakers share some similar characteristics to the Dunlavy speakers. He has mentioned Dunlavy a few times. The BA2018 is a good board. It has nice imaging. It will impart a small amount of flavor to the sound but in a nice way. There was some recent talk about a balanced BA2018 wiring etc in the main thread. Worth a look
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I did end up reflowing with no clean flux and cardas silver alloy. Also cleaned all the old flux. I think this was just a good preventative maintenance exercise. Not testing yet, but it's on the near horizon. Zm, think it's ok to test voltage drop across all the source resistors withe the heatsink ops module tilted from the chassis and secured with the lower bolts? I mean I'm testing for relative match not absolute values right? Sometimes I figure out the answer to my own question when I type... Peace
She's been on for over 24hrs and sounds better just likey my Audi is faster when clean. Yeah totally an ocd response, or perhaps some level of the autistic spectrum or so I'm told by my daughter...
I will for sure.. what would be your choice front buffer for this beautiful piece of gear manufacturer by papa and his people. Balanced B1 or Wayne's balanced ? Feeling my main rig not right to without a fully diy component.
feel free to use RCA input (with XLR shorting plug) and leave SE to Bal conversion to amp itself
B1 Balanced is really twice SE, simply because (usual) JFet buffer can't be made proper balanced, so that's the way
Wayne didn't develop proper balanced arrangement for his line stage, so that again leaves you with twice SE arranged in balanced fashion ... far from qualities of proper balanced/differential stage where signal polarities are conditioned together, not as two independent halves
so, either find a way to build, borrow, steal, buy proper PL balanced stage ....... or feed it with whatever good SE preamp you have, ditto in SE input
though, it just came to my mind - see Balanced Iron Pre - killer good for Peanuts
B1 Balanced is really twice SE, simply because (usual) JFet buffer can't be made proper balanced, so that's the way
Wayne didn't develop proper balanced arrangement for his line stage, so that again leaves you with twice SE arranged in balanced fashion ... far from qualities of proper balanced/differential stage where signal polarities are conditioned together, not as two independent halves
so, either find a way to build, borrow, steal, buy proper PL balanced stage ....... or feed it with whatever good SE preamp you have, ditto in SE input
though, it just came to my mind - see Balanced Iron Pre - killer good for Peanuts
ZM, So would an Aleph P do the trick? I know they are aging, but that makes me want it more. Is it high voltage MOSFET gain? 210? Any chance you might have a schematic? Could possibly swing an X1 if that's the ticket and I wouldn't ask for a schema. A basic principle of that circuit would suffice. Probably going to buy a PS audio PSA-2 but man, I understand the pass labs synergy between components is intentional. Peace
of course Aleph P would do the trick
there is just one ( slight) Caveat - Aleph P is jobbie having very funny attenuator - not regular/common volume attenuator, but more in fashion of variable load for active elements ( read - mosfets)
if you can do that exactly, instead of resorting to usual way of attenuating, it's worth doing/making Aleph P
and it's really best if you can devise relays switched resistor matrix,, for which you need proper logic control (so hardware and software); in circulating service manual there is shown actual resistor matrix, but of course no logic hardware nor software
it can be replaced with rotary switch and resistor group, but that demands some recalculating, for which yo need to have full understanding of circuit
regarding schematic, search through forum ( maybe with ggl) will deliver
try this: https://www.diyaudio.com/community/...]=1&c[nodes][0]=8&c[title_only]=1&o=relevance
now, I believe you could get better sonic outcome if you go BBA3 route (that's BA3 balanced FE/preamp)
much easier to make properly/as is, pretty straightforward, also using regular volume pot
there is just one ( slight) Caveat - Aleph P is jobbie having very funny attenuator - not regular/common volume attenuator, but more in fashion of variable load for active elements ( read - mosfets)
if you can do that exactly, instead of resorting to usual way of attenuating, it's worth doing/making Aleph P
and it's really best if you can devise relays switched resistor matrix,, for which you need proper logic control (so hardware and software); in circulating service manual there is shown actual resistor matrix, but of course no logic hardware nor software
it can be replaced with rotary switch and resistor group, but that demands some recalculating, for which yo need to have full understanding of circuit
regarding schematic, search through forum ( maybe with ggl) will deliver
try this: https://www.diyaudio.com/community/...]=1&c[nodes][0]=8&c[title_only]=1&o=relevance
now, I believe you could get better sonic outcome if you go BBA3 route (that's BA3 balanced FE/preamp)
much easier to make properly/as is, pretty straightforward, also using regular volume pot
Thank you for your detailed response! Super informative! I'm still trying to wrap my head around balanced circuits. Going to try PS audio PCA-2 with separate psu for kicks, although I'm sure I'll discover much low hanging fruit. Yeah PS used some cheap **** caps and Sparkos regs are oh so quieit! That's kind of where I'm at these days. Discovering. Learning. Rebuilding, Reimagining with modern components but respecting the topology and really just tuning the old dogs.
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Biased the X150.5. First round dodgy af, second times a charm! Exercising pots helped... Started with a range of 93-125mv (4) @ 47
5 . Ended up after second round 140mv solid for all 4. And diff 0-1, abs, single dig. (mv) @54. Pulled the ground straps added load and 50deg idle ! Sitting at 47 RN listening to Daniel Lanois, Needle at 12 o' c lock. Not moving much. Pretty cool. Still looking to measure voltage drop across the source resistors..ordered qty-100 ERX-3SJR47. 3.3k harder to find. 5w easy, bigger. Probably fit. 100 still cheap. Peace
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Biased the X150.5. First round dodgy af, second times a charm! Exercising pots helped... Started with a range of 93-125mv (4) @ 47
5 . Ended up after second round 140mv solid for all 4. And diff 0-1, abs, single dig. (mv) @54. Pulled the ground straps added load and 50deg idle ! Sitting at 47 RN listening to Daniel Lanois, Needle at 12 o' c lock. Not moving much. Pretty cool. Still looking to measure voltage drop across the source resistors..ordered qty-100 ERX-3SJR47. 3.3k harder to find. 5w easy, bigger. Probably fit. 100 still cheap. Peace
Thank you for your detailed response! Super informative! I'm still trying to wrap my head around balanced circuits. Going to try PS audio PCA-2 with separate psu for kicks, although I'm sure I'll discover much low hanging fruit. Yeah PS used some cheap **** caps and replacing the ti regs with Sparkos. That's kind of where I'm at these days. Discovering. Learning. Rebuilding, Reimagining with modern components but respecting the topology and really just tuning the old dogs and quieting PS.
.
Biased the X150.5. First round dodgy af, second times a charm! Exercising pots helped... Started with a range of 93-125mv (4) @ 47
5 . Ended up after second round 140mv solid for all 4. And diff 0-1, abs, single dig. (mv) @54. Pulled the ground straps added load and 50deg idle ! Sitting at 47 RN listening to Daniel Lanois, Needle at 12 o' c lock. Not moving much. Pretty cool. Still looking to measure voltage drop across the source resistors..ordered qty-100 ERX-3SJR47. 3.3k harder to find. 5w easy, bigger. Probably fit. 100 still cheap. Peace
.
Biased the X150.5. First round dodgy af, second times a charm! Exercising pots helped... Started with a range of 93-125mv (4) @ 47
5 . Ended up after second round 140mv solid for all 4. And diff 0-1, abs, single dig. (mv) @54. Pulled the ground straps added load and 50deg idle ! Sitting at 47 RN listening to Daniel Lanois, Needle at 12 o' c lock. Not moving much. Pretty cool. Still looking to measure voltage drop across the source resistors..ordered qty-100 ERX-3SJR47. 3.3k harder to find. 5w easy, bigger. Probably fit. 100 still cheap. Peace
Attachments
you measured - what - 140mV between checking "bias" headers on motherboard
that's exactly voltage sag across 2 series source resistors in output
what's room temperature?
hope you set it to +25C at top of heatsinks, recheck in Summer, when you can allow +30C, as prescribed in Service manual
except if you are in some wakoo yank neck of wood, where summer is all year long
that's exactly voltage sag across 2 series source resistors in output
what's room temperature?
hope you set it to +25C at top of heatsinks, recheck in Summer, when you can allow +30C, as prescribed in Service manual
except if you are in some wakoo yank neck of wood, where summer is all year long
Yes, Bias points A B on input boards. Room @ 25 deg C. Dialed it back a bit to 125 mv for each quadrant. Then, tested voltage drops across 0R47 n channel source resistors for the 2 quadrants accessible without tilting the heatsinks. In Theory should be close to 62.5 mv right? Left Channel A Quadrant front to rear 58,65,57,68,59,65,56,68,64,67 (mv) Right Channel B Quadrant 69,64,72,66,73,65,75,70,74,67 (mv). Definitely greater than 10% drift..... Looks like I'll be pulling the output boards, replacing resistors and testing mosfets. Upside is better sound when fixed!
no just chill, no need to fiddle with resistors and mosfets
taking in account value of source resistors, that being enough to nor worry about discrepancy you have
just recheck their torque
taking in account value of source resistors, that being enough to nor worry about discrepancy you have
just recheck their torque
The torque is supposed to be around 9-10 inch lbs right? Just snug enough to compress the silicone pads properly.
Source resistors themselves are 5% tolerance.
Source resistors themselves are 5% tolerance.