Excuse the ungainly title.
I am hoping this can be placed here without too much controversy since it does not concern a Nelson Pass design but it is used with a system that has many benefits of that singular superlative imagination.
For the bass I am using two of the YAMAHA YDP2006 for DSP and crossover. As is usual with these things it is full of superfluous opamp stages that are useless for home audio. The last few days I have been bypassing them and so far all is working better than I would ever expected. Chock full of the ubiquitous 5532s. Even they are capable of revealing the absence of themselves!
It is from the 1990's so it is all through hole and uses the PCM63 DAC.
My question is: there are bipolar electrolytics at the (balanced) outputs - could one try the battery biasing trick that JBL does with electrolytics in some of their crossovers for a coupling cap in (ostensibly) a line stage?
Would biasing the caps make any difference at all over just using a nonpolar electrolytic? Not enough room for film - the circuit uses a 250 uF nonpolar for each pole of the balanced output. I have some 1000 uF SILMICS lating about and thought I would try those.
Any thoughts?
I am hoping this can be placed here without too much controversy since it does not concern a Nelson Pass design but it is used with a system that has many benefits of that singular superlative imagination.
For the bass I am using two of the YAMAHA YDP2006 for DSP and crossover. As is usual with these things it is full of superfluous opamp stages that are useless for home audio. The last few days I have been bypassing them and so far all is working better than I would ever expected. Chock full of the ubiquitous 5532s. Even they are capable of revealing the absence of themselves!
It is from the 1990's so it is all through hole and uses the PCM63 DAC.
My question is: there are bipolar electrolytics at the (balanced) outputs - could one try the battery biasing trick that JBL does with electrolytics in some of their crossovers for a coupling cap in (ostensibly) a line stage?
Would biasing the caps make any difference at all over just using a nonpolar electrolytic? Not enough room for film - the circuit uses a 250 uF nonpolar for each pole of the balanced output. I have some 1000 uF SILMICS lating about and thought I would try those.
Any thoughts?
JBL trick is having a goal to involve some DC across polar cap , because they believe(d) that that arrangement is resulting in better sound
if caps in question are having some amount of DC (at least 10V) , then they're already put in desired situation
if that is not the case (and I believe it isn't - they're blocking just minuscule DC offset) , you can use JBL trick and make your own conclusion
though ..... dunno which batteries to use ...... maybe small (8-10mm Dia) cylindrical ones , of 10 or 12V ...... some DMM are using these , also some photo gadgets .......
if caps in question are having some amount of DC (at least 10V) , then they're already put in desired situation
if that is not the case (and I believe it isn't - they're blocking just minuscule DC offset) , you can use JBL trick and make your own conclusion
though ..... dunno which batteries to use ...... maybe small (8-10mm Dia) cylindrical ones , of 10 or 12V ...... some DMM are using these , also some photo gadgets .......
Why would the circuite call for 250uf caps ? I know it was often the case that a large electrolytic coupling was often used where a much smaller value film cap would work fine.
I am just wondering if that could be the case here . I did use a biased cap in my Pass A40 and was very pleased with the result.
I am just wondering if that could be the case here . I did use a biased cap in my Pass A40 and was very pleased with the result.
Thanks, ZM.
AS always I appreciate your knowledge, counsel and opinion.
I was hoping I could get away with no couplers but that was made clear very quickly.
DC offset is about 47mV across both legs.
One channel is for a loudspeaker with 80 hz high pass and I am using PP film there but figure for the other channel I need serious capacitance. These caps are not part of the crossover filters.
Could very well be gilding the lily (even though every time I write that I think of a great malapropism: gelding the lily - which might be more accurate) it seems worth a try. Not enough room for a 250 uF film cap and I am not sure one would do that much better in the 15 to 60 hz range. Though I realize one would not need 250 uf of film to replace 250uF of electrolytic. I hope that is not something I made up ...
I will use the good old nominal 9 volts battery like what are used in affordable multi meters.
Something I have wanted to try and would have but it is always good to have the guidance from the man who has tried almost everything. And whose instincts are second to one. And quite a one it is!
Thanks and take care, ZM.
AS always I appreciate your knowledge, counsel and opinion.
I was hoping I could get away with no couplers but that was made clear very quickly.
DC offset is about 47mV across both legs.
One channel is for a loudspeaker with 80 hz high pass and I am using PP film there but figure for the other channel I need serious capacitance. These caps are not part of the crossover filters.
Could very well be gilding the lily (even though every time I write that I think of a great malapropism: gelding the lily - which might be more accurate) it seems worth a try. Not enough room for a 250 uF film cap and I am not sure one would do that much better in the 15 to 60 hz range. Though I realize one would not need 250 uf of film to replace 250uF of electrolytic. I hope that is not something I made up ...
I will use the good old nominal 9 volts battery like what are used in affordable multi meters.
Something I have wanted to try and would have but it is always good to have the guidance from the man who has tried almost everything. And whose instincts are second to one. And quite a one it is!
Thanks and take care, ZM.
I suspect you are right. I am using 4 uF film for one channel as you may read below but there is not enough room for a second set and I have the SILMICs on hand and no large films so for the first two octaves I am hoping this will be plenty good. I have read people who like the sound of electrolytics down there. So it might be the best compromise.
THANKS for you advice.
PS I have read many of your posts and know we are in the same area of the state. But where I am you might as well be in Montana! Such a shame that getting around here is such a pain. I am in north Fulton county. One of these days we should make an attempt to meet each other.
Yes, these are the end of the line.
Looking into an amplifier with a balanced input - 15K ohms total input impedance. Not seriously low. I guess as cheap as electrolytic capacitance is YAMAHA thought "why not" use 250 uF per leg?
I have 1000uF SILMICs on hand (500 uf in series) which is even more absurd but they are what I have and I cannot see any benefit of ordering something for this.
Unless given a reason to reconsider ...
Thanks and take care,
Well, I can report it does not work on balanced outputs.
As if there were no output capacitors.
Guess I will go with the smallest films I can find.
The channel with films measures as you would expect with minuscule offset the back to back electrolytics measure much more, with no bias of, course.
I am only working on one of the boxes at a time. Will be interesting to see that the offset is with the stock nonpolar electrolytics.
As as aside, I thought this thing did a good job for my low frequency duty as it was but I am astounded how much more "dynamic expression" there is with my changes.
For anyone interested:
Bypassing the fake balanced input - I do not have a balanced line stage to feed it so this seemed like an obvious change. Less one 5532 stage.
bypassing the "emphasis circuit" which even when out of the circuit has the signal go through two additional 5532 stages.
For the output, so far, just changing the l-pad to reduce the output to raise it about 6 dB. So low before the little LED indicators were telling me I was clipping much too often. With full output REALLY noisy.
I tried bypassing the other side of the "emphasis circuit" and on first try I got no output. Maybe there is something there that the DAC needs even though there is one 5532 after the DAC. I tried to bypass two stages next if will just bypass one.
Lots of seemingly superfluous high frequency filtering, you wonder just how many low pass filters one could need? I figure with the thing only being asked to go as high as 1kHz and that at a very minimal level much of this is not needed.
For the bass the DSP is required. I used these things for the longest times as just crossovers - what an idiot. Room treatment and judicious DSP are very worthwhile. I am nervous about using those things above that. I imagine you could get a decent sound but I would fear lots of the subtleties would be lost and gone forever. I have the same fear for the newer units even in the bass.
As if there were no output capacitors.
Guess I will go with the smallest films I can find.
The channel with films measures as you would expect with minuscule offset the back to back electrolytics measure much more, with no bias of, course.
I am only working on one of the boxes at a time. Will be interesting to see that the offset is with the stock nonpolar electrolytics.
As as aside, I thought this thing did a good job for my low frequency duty as it was but I am astounded how much more "dynamic expression" there is with my changes.
For anyone interested:
Bypassing the fake balanced input - I do not have a balanced line stage to feed it so this seemed like an obvious change. Less one 5532 stage.
bypassing the "emphasis circuit" which even when out of the circuit has the signal go through two additional 5532 stages.
For the output, so far, just changing the l-pad to reduce the output to raise it about 6 dB. So low before the little LED indicators were telling me I was clipping much too often. With full output REALLY noisy.
I tried bypassing the other side of the "emphasis circuit" and on first try I got no output. Maybe there is something there that the DAC needs even though there is one 5532 after the DAC. I tried to bypass two stages next if will just bypass one.
Lots of seemingly superfluous high frequency filtering, you wonder just how many low pass filters one could need? I figure with the thing only being asked to go as high as 1kHz and that at a very minimal level much of this is not needed.
For the bass the DSP is required. I used these things for the longest times as just crossovers - what an idiot. Room treatment and judicious DSP are very worthwhile. I am nervous about using those things above that. I imagine you could get a decent sound but I would fear lots of the subtleties would be lost and gone forever. I have the same fear for the newer units even in the bass.
I know that Greg Timbers swears by back-to-back electrolytics with some
polarization, and he has paid close attention to it.
The primary distortion component is 2nd harmonic on a biased electrolytic,
and back-to back tend to cancel it.
When the SIT-3 comes out, you will see an interesting wrinkle on the
technique.
At moment, only person outside the factory who knows is ZM.....
polarization, and he has paid close attention to it.
The primary distortion component is 2nd harmonic on a biased electrolytic,
and back-to back tend to cancel it.
When the SIT-3 comes out, you will see an interesting wrinkle on the
technique.
At moment, only person outside the factory who knows is ZM.....
When I built a Pass A40 I used a pair of back to back 470uf caps with a 1uf film bypass cap for C2 Then I used a 9v battery to supply bias through a 2 meg resistor. But at first I fired the amp up without any bias voltage applied to the cap. Then as I applied the bias voltage it was like a veil was slowly removed . It was a huge difference. But that was 35 years ago and caps back then weren't nearly as good as our new ones.
I attached the battery ground to pin 1 of the output XLR. On the schematic it is connected directly to ground.
I saw in the article by a fellow named Poth on the ENJOY THE MUSIC site - he was doing this with a loudspeaker crossover - he attached the battery ground before the "first" cap and used a 1 meg resistor for each leg of the battery.
I did not try this since I figure that this must not work in an amplifier like it does in a crossover.
Should I give that a try?
Looking at the schematic again I see pin 1 is connected to both signal and power ground. Maybe I should try a power ground point? Not as easy to connect to - I used the easiest one.
I saw in the article by a fellow named Poth on the ENJOY THE MUSIC site - he was doing this with a loudspeaker crossover - he attached the battery ground before the "first" cap and used a 1 meg resistor for each leg of the battery.
I did not try this since I figure that this must not work in an amplifier like it does in a crossover.
Should I give that a try?
Looking at the schematic again I see pin 1 is connected to both signal and power ground. Maybe I should try a power ground point? Not as easy to connect to - I used the easiest one.
well , one needs all the knowledge , for proper operation of OPLDF
if only I knew what that was ...
I would use it.
no difference as long cap is properly biased with voltage
did you tried small cap values , according to formula?
I just had those 1000 uF SILMICS close at hand so that is what I used.
I will look harder for some smaller values.
These without the bias seem to be doing fine though i know the value is ludicrous. The channel in question has a 50 hz low pass so "air" and "delicacy" are not what matters here. I simply wanted to see if the idea would work in an amplifier.
Do you think these jumbo caps could be the result of the biasing adding BIG noises? Would placing a resistor between battery ground and circuit ground be worth a try? Instead of one 2 meg a 1 meg on each battery leg?
I will try some smaller ones. And different resistor arrangements.
Thanks for your interest.
I will look harder for some smaller values.
These without the bias seem to be doing fine though i know the value is ludicrous. The channel in question has a 50 hz low pass so "air" and "delicacy" are not what matters here. I simply wanted to see if the idea would work in an amplifier.
Do you think these jumbo caps could be the result of the biasing adding BIG noises? Would placing a resistor between battery ground and circuit ground be worth a try? Instead of one 2 meg a 1 meg on each battery leg?
I will try some smaller ones. And different resistor arrangements.
Thanks for your interest.
whatever value of resistor you put there , you'll not hear difference , simply because ( if cap is OK) polarizing current is minuscule
I say - put properly sized solid cap there and forget it
though , as you're Master of your own Destiny ( or at least destiny of your gadgets
) , you'll do what pleases you most
I say - put properly sized solid cap there and forget it
though , as you're Master of your own Destiny ( or at least destiny of your gadgets
) , you'll do what pleases you most
While waiting for some caps I will try using the plus 15 volts supply rail - taken from the last opamp's pin 8 and see if that stops the noise.
Found out the amp being driven by this channel is 10K input - 4uf - 4 Hz.
I will use 10 uF just to retain some level of absurdity for this channel. The other 4 uF is plenty.
Found out the amp being driven by this channel is 10K input - 4uf - 4 Hz.
I will use 10 uF just to retain some level of absurdity for this channel. The other 4 uF is plenty.
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