Professor Smith,
IRT the caps.
I have some DC on my systems ouput to the speakers for some reason. Getting that sorted. However and to my point, if I put a 33pf cap in series with the speaker it removes ALL sound. If I up the capacitance to .22uf I get some treble back and I can hear some vocals. When I up it to 10uf I get treble and mids but high mids. What is happening is that the cap only allows certain frequencies to pass through and does not allow DC to pass through. So, in trying to get rid of DC I am learning a bit about caps behavior when filtering frequencies and blocking DC.
Your caps are doing some of the same thing. They are not adding bass but allowing more of the available bass frequencies to pass through. Take a couple of those caps you have and try them on the + of your speaker output inline with the speaker wire and you will see what I mean. Try from under 1uf up to whatever your highest is. You will not harm your speaker you will just now have hands on demonstration of what the cap is doing when it filters frequencies.
So, to my understanding thats what the cap does when it is in the signal path. Also when in the power supply it obviously allows more bass if your transformer can not keep up with the demand for more power. Then the cap acts as a resevoir of power to draw from.
uriah
IRT the caps.
I have some DC on my systems ouput to the speakers for some reason. Getting that sorted. However and to my point, if I put a 33pf cap in series with the speaker it removes ALL sound. If I up the capacitance to .22uf I get some treble back and I can hear some vocals. When I up it to 10uf I get treble and mids but high mids. What is happening is that the cap only allows certain frequencies to pass through and does not allow DC to pass through. So, in trying to get rid of DC I am learning a bit about caps behavior when filtering frequencies and blocking DC.
Your caps are doing some of the same thing. They are not adding bass but allowing more of the available bass frequencies to pass through. Take a couple of those caps you have and try them on the + of your speaker output inline with the speaker wire and you will see what I mean. Try from under 1uf up to whatever your highest is. You will not harm your speaker you will just now have hands on demonstration of what the cap is doing when it filters frequencies.
So, to my understanding thats what the cap does when it is in the signal path. Also when in the power supply it obviously allows more bass if your transformer can not keep up with the demand for more power. Then the cap acts as a resevoir of power to draw from.
uriah
Professor smith said:
that's nature of the things (ie. physics)
Professor smith said:
tighter bass
Professor smith said:
not just like that - easily ....... you still have that pot before B1 input cap , and that pot is DC coupled to gnd
Professor smith said:
again - as I see it - you have some other things to do first - little thinking about basics ;
ppl around here are more than willing to give you ( or anyone else ) few tricks and tips , but they usually don't have enough time for teaching Kirchof's Law etc. to any grunschnabbel 😉
believe me - doing your own homework can only be beneficial ......
so , go HERE for start ........
Zen Mod said:
linning puzzles - making things without understanding how they works ;
we all started somewhere , without too much knowledge (NB that I'm still stuck there) , but we can only progress if we try to learn bit by bit
there is numerous number of online tutorials ; few of them are any of Papa's 3 sites - go there , download all the pdfs and read ........ read ..... read .
4u7 will gives you half bass youcan have with 10uF
so - as you already have 10uF on DAC output - just make B1 with split supply , get rid of input cap ( not because of any problem that 1uF on B1 input isn't capable of transferring full bass energy , but because of addition of phase twists you have in every cap in chain )
two caps in chain are more than enough ; you don't need third one .
that's at least my (always) humble opinion
😉
but can you tell me if my calculation is correct. The dac ouput resistance combined with the buffer input resistance guves us about 400 ohms which combined with the 10Uf blocker on the dac, gives a corner cut off frequency of about 40hz.
Is this what is accounting for the lack of bass weight?
If so should I just double the dc cap to 20Uf?
by the way..
what is a phase twist?
Professor smith said:
If I might toss in a few things...
(With the disclaimer that the boys are both sick & miserable & screaming, meaning that I can't think due to the ruckus...)
1) There are a number of posts over the last few pages where people have spoken very loosely. There are times and places where this sort of thing is fine, but perhaps a little more precision in communication would assist.
2) I make no claims regarding assigning blame for lack of bass, but if you're calculating that your roll off point is 40Hz or so, then yes, that's completely unacceptable in a hi-fi rig. Bear in mind that the roll off point, by definition, means that the response is already down 3dB at that point. That's quite noticeable. You'll get various answers if you ask how many dB--or fractions thereof--are detectable by the average human ear, but most will say that 1dB is audible and 3dB is "half as loud." If your -3dB point is at 40Hz, you're going to be audibly down for an octave or more above that (remember that an octave is a doubling [or halving] of the frequency in question) so we're talking about diminished response to 80Hz or higher. Yes, I can well believe that you're less than pleased about the sound.
3) You will also have heard that 20Hz is the lower limit of human hearing. Don't be tempted to set the -3dB point at 20Hz. See above.
4) Most decent audio gear has a low end roll off below 10Hz--in some cases well below 1Hz. I would suggest that you aim for something in that region, the lower the better. I feel that 1Hz is the upper limit, but I'm notorious for overkill/tweak/excess.
5) Several posts have mentioned phase shift. Phase shift gets complicated. Not that the concept itself is hard--quite simple, in fact--but the effects are not as straightforward as you might like. Phase shift does not generally result in a perceived lack of quantity of bass, but can matter in terms of the quality. Before worrying about the phase shift, I'd suggest that you get the bass level squared away. In general, frequency response is a first order sort of problem, whereas phase shift is a second or third order sort of thing. Note that if you lower the roll off point far enough, the phase shift will cease to be a problem anyway. Phase shift is inherent in filters. You can't make it go away. The next best thing is to move it far enough out of the listening band that it ceases to cause problems.
I'll try to get back in here and read the last few pages more carefully later on. There may be something I missed. For the nonce, I'd suggest that you increase the coupling cap considerably, even if you just use some sort of junk box cheap part to start with. You can always refit with a better quality part once you get the value fixed up. If my suspicions are correct, I think you'll find that will cure the problem.
Oh, and one more thing, don't forget that paralleling caps works wonders when you don't have the desired value on hand.
Grey
GRollins said:
very good advice, thanks for that Grey.
Couple of things to say:
I have simply shorted out the 10Uf cap on the cd player altogether. But this has not solved the bass issue. Am I allowed to short it out? It hasnt seemed to affect the performance, its just that it hasnt solved the bass issue either.
I havent got a spare 10Uf cap to hand thats the only thing..
But I have 2 questions: Is my calculation correct? The cd Dac impedance is 5kohm and the input pot of the B1 is 20kohm
and secondly, why didnt the short circuit across the cap solve the problem?
Thanks
Is this going to help him?
f=1/(2*pi*r*c)
F= the desired frequency and above that you want to hear
Pi=22/7
r=ohms
c=farads
So this is for a coupling capacitor and resistor for a high pass filter. You have to take into account the resistance after the cap. Not sure if you take what is upline from it into consideration. The resistance AFTER the cap is really the "r" you put in. I just found this and am learning to so this is about all I have figured out for this right now. Hopefully someone else will help, but I think that this formula should have been talked about already and I think that without mentioning the formula this is actually what Gray was talking about.
If I am wrong, and I am sure I am wrong at some point about this, please correct me.
Uriah
f=1/(2*pi*r*c)
F= the desired frequency and above that you want to hear
Pi=22/7
r=ohms
c=farads
So this is for a coupling capacitor and resistor for a high pass filter. You have to take into account the resistance after the cap. Not sure if you take what is upline from it into consideration. The resistance AFTER the cap is really the "r" you put in. I just found this and am learning to so this is about all I have figured out for this right now. Hopefully someone else will help, but I think that this formula should have been talked about already and I think that without mentioning the formula this is actually what Gray was talking about.
If I am wrong, and I am sure I am wrong at some point about this, please correct me.
Uriah
Professor smith said:
Click on "post reply" and at the bottom of the page it says "attach file". Click browse and look for the image in your HD. Then click ok or save when prompted.
I am now getting thunderous bass like never before, after a slight change in speaker positioning and I also changed the source to a cheap dvd player. And I am hearing proper imaging, and dynamics, the bass is deep but not overblown.
But whats wrong with my cd player? Why doesnt it give me the same sound as the cheap dvd player?
I would like to replace the dvd player but I dont want to lose any of what I'm hearing now...
But whats wrong with my cd player? Why doesnt it give me the same sound as the cheap dvd player?
I would like to replace the dvd player but I dont want to lose any of what I'm hearing now...
can someone help me with this please?
I have some questions:
Does it matter if I omit the LED on the buffer?
Is it good to lower the output resistance and how?
many thanks,
John
I have some questions:
Does it matter if I omit the LED on the buffer?
Is it good to lower the output resistance and how?
many thanks,
John
Hi,
yes, you can omit the LED. It is just an indicator that draws a constant current from the power input filter.
The 1k0 could probably be reduced. But, this will reduce the stability margin and may affect the performance of the circuit.
Has anyone else tried lower values for r104?
I would like to see 200r but Nelson Pass must have a reason (or many) for setting it to 1k0.
yes, you can omit the LED. It is just an indicator that draws a constant current from the power input filter.
The 1k0 could probably be reduced. But, this will reduce the stability margin and may affect the performance of the circuit.
Has anyone else tried lower values for r104?
I would like to see 200r but Nelson Pass must have a reason (or many) for setting it to 1k0.
well because Nelson states in the paper that the pot sets the input impedance so the higher the better no?
Professor smith said:
There is a small and nonlinear input capacitance to the JFET, so the
best performance is obtained with values at 50K or below. You can
use 100K if you really have a need.
I have some more questions.
I changed the ouptut cap from 4Uf to 10Uf since somebody said this would give me double bass but now, I seem to be getting less bass again. What is happening?
Also previously I had a small cap in parallel just at the input, would this affect the bass?
I changed the ouptut cap from 4Uf to 10Uf since somebody said this would give me double bass but now, I seem to be getting less bass again. What is happening?
Also previously I had a small cap in parallel just at the input, would this affect the bass?
I hope they didn't say that!!!Professor smith said:
Doubling the value of the DC blocking cap will half the frequency of the High Pass filter. The effect will be to reduce the 20Hz attenuation from -0.2dB to -0.1dB, but dependent on precise component values.
It will not increase the bass.
- Status
- Not open for further replies.