This is in response to your question about how to measure
How are you making your measurements? You can't really use a standard multimeter reliably to detect line level music; you need a test tone, probably in the 60-300Hz range for a basic multimeter, and meter in the AC 0-200mV or 0-2V range. A computer sound card is a great source for test tones. Or you can just listen to the output (using speakers you can afford to throw away, and and AC coupled amp!)
If you have a scope, scope + test tones is the easiest way to prototype.
In response to the earlier tests
So for one thing, I'm not convinced that your input is a dead short. Now, throwing that out the window for a second, if there really is no signal at R3 (input side), then you either have the input bridged to ground, or your values for R3 and R4 are totally wrong. (too low)
Check for solder bridges, components in wrong pads, or connection problem to source.
4. This is the next step. It's depressingly easy to fit 10 ohms instead of 10k ohms...that could be your problem.
5. Yes, these are optional. Just ruling them out.
How are you making your measurements? You can't really use a standard multimeter reliably to detect line level music; you need a test tone, probably in the 60-300Hz range for a basic multimeter, and meter in the AC 0-200mV or 0-2V range. A computer sound card is a great source for test tones. Or you can just listen to the output (using speakers you can afford to throw away, and and AC coupled amp!)
If you have a scope, scope + test tones is the easiest way to prototype.
In response to the earlier tests
So for one thing, I'm not convinced that your input is a dead short. Now, throwing that out the window for a second, if there really is no signal at R3 (input side), then you either have the input bridged to ground, or your values for R3 and R4 are totally wrong. (too low)
Check for solder bridges, components in wrong pads, or connection problem to source.
4. This is the next step. It's depressingly easy to fit 10 ohms instead of 10k ohms...that could be your problem.
5. Yes, these are optional. Just ruling them out.
Things are a little better!
Some progress...
Found a dead short in an RCA cable. At least I am up to getting the buffered out and the HP_Out signals. That part's working great!
However, I have nothing at the BP/LP_OUT other than a big DC value, ~ 1.5V or more. On the O screen it looks like a big green fog. Is this HF oscillation? I have decent signal on pins 6 & 7 of IC3, but a couple volts and no signal on pins 2 & 3 of IC3 and more DC on pins 2 & 3 and 6 & 7 of IC2. R801 will reduce the voltage but there appears to be no underlying signal.
I do have decent signal on 1St Order_LP. R802, R803, R902, & R903 are the correct values.
The scope's been invaluable.
Some progress...
Found a dead short in an RCA cable. At least I am up to getting the buffered out and the HP_Out signals. That part's working great!
However, I have nothing at the BP/LP_OUT other than a big DC value, ~ 1.5V or more. On the O screen it looks like a big green fog. Is this HF oscillation? I have decent signal on pins 6 & 7 of IC3, but a couple volts and no signal on pins 2 & 3 of IC3 and more DC on pins 2 & 3 and 6 & 7 of IC2. R801 will reduce the voltage but there appears to be no underlying signal.
I do have decent signal on 1St Order_LP. R802, R803, R902, & R903 are the correct values.
The scope's been invaluable.
It sounds like you have the following jumpered:
JP1, JP2, JP4, JP5
JP3 is jumpered 1+2
You should have nothing connected to AUX1 and AUX2. This setup sounds correct. It does sound like you have oscillation.
What are your xover settings? If you have it set to 1st order, you must not have anything jumpered in the first MULTI block of capacitors, or you will get oscillation. Are your opamps warm? If they get hot, beware of damaging them.
It's also possible that you are getting oscillation because you left out the bandwidth limiting caps at the input. I remember testing NE5532 successfully without these caps, but OPA2134 is faster. I don't really think this is happening since the input stage is stable, but it is possible since the crossover stages are more prone to oscillation.
JP1, JP2, JP4, JP5
JP3 is jumpered 1+2
You should have nothing connected to AUX1 and AUX2. This setup sounds correct. It does sound like you have oscillation.
What are your xover settings? If you have it set to 1st order, you must not have anything jumpered in the first MULTI block of capacitors, or you will get oscillation. Are your opamps warm? If they get hot, beware of damaging them.
It's also possible that you are getting oscillation because you left out the bandwidth limiting caps at the input. I remember testing NE5532 successfully without these caps, but OPA2134 is faster. I don't really think this is happening since the input stage is stable, but it is possible since the crossover stages are more prone to oscillation.
I tried it just like the picture in the manual... which doesn't make sense to me. That is after the high pass, feed into the low pass. I think that would create a band pass if I'm not mistaken. I want to do a two way cross...
So I think I should have the jumpers set as follows...
JP1 - JP5 ---> HP
JP1 - JP2 - JP4 - JP3 (1-2) --->LP
I now I'll sort this out, it's just the learning curve is steep. Thanks for the suggestions...
So I think I should have the jumpers set as follows...
JP1 - JP5 ---> HP
JP1 - JP2 - JP4 - JP3 (1-2) --->LP
I now I'll sort this out, it's just the learning curve is steep. Thanks for the suggestions...
...and while we are at it, I don't understand HP and LP FRQ_1 vs. FRQ_2. Does this actually create a band pass for both the HP and LP sections???
What would the settings be if a fellow wanted a crossover frequency of 3000 Hz while allowing the HF to roll off at the top and the LF to rill off at the bottom?
What would the settings be if a fellow wanted a crossover frequency of 3000 Hz while allowing the HF to roll off at the top and the LF to rill off at the bottom?
I don't understand what your little jumper drawing means, although I think you are just organizing the signal flow; I told you what I thought it meant. If the jumpers are set as I stated you will have HP and LP. Jumpers are ON or OFF, except for JP3. (If you change JP3 to 2+3 you will have bandpass, but you need to remove some jumpers so you don't short PREOUT to LP out. Let's stay away from this since you aren't doing BP.)
FRQ1 and FRQ2 are normally identical. You shouldn't set these asymmetrically unless you know what you are doing. It has nothing to do with bandpass, only the fact that two resistors need to change for 2nd order system.
FRQ1 and FRQ2 are normally identical. You shouldn't set these asymmetrically unless you know what you are doing. It has nothing to do with bandpass, only the fact that two resistors need to change for 2nd order system.
HF will roll off at the BOTTOM of it's range (3000Hz). LF will roll off at the TOP of its range (3000Hz). Therefore set all FRQ to 300, all multiplier to 10x, JP3 to 1+2 and all other jumpers set. And your Q is probable 0.5-1.0.
What they forgot: (quote from PassLabs XVR1 manual):
"Some audio products are designed for anybody who can put batteries in a flashlight. This
product is not like that.
Some audio products are designed so that you don’t have to study the manual. This
product is not like that, either.
Some audio products are designed so that you plug them in and you don’t have to fool
around with them for a year before the system is greatly improved…."
I also thinks that the manual is difficult to understand...
But easier, if you print out the schematics, find the jumpers, and look where they go, and if you need them...
Arne K
"Some audio products are designed for anybody who can put batteries in a flashlight. This
product is not like that.
Some audio products are designed so that you don’t have to study the manual. This
product is not like that, either.
Some audio products are designed so that you plug them in and you don’t have to fool
around with them for a year before the system is greatly improved…."
I also thinks that the manual is difficult to understand...
But easier, if you print out the schematics, find the jumpers, and look where they go, and if you need them...
Arne K
Manual
Feel free to explain what you don't understand, but please consult the schematics AND manual - this makes things easier.
Also please make notes as you go along, I don't know the different problems you have with the documentation unless someone points me to them.
Email me with your questions, and maybe we can make a Q/A section of the manual.
I will try to update the manual, but this takes some time and I'm pretty busy at work these days (and nights).
\Jens
Cobra2 said:
Feel free to explain what you don't understand, but please consult the schematics AND manual - this makes things easier.
Also please make notes as you go along, I don't know the different problems you have with the documentation unless someone points me to them.
Email me with your questions, and maybe we can make a Q/A section of the manual.
I will try to update the manual, but this takes some time and I'm pretty busy at work these days (and nights).
\Jens
Cobra2, I know where you are coming from, and I agree there are some things that could be spelled out more clearly, but I just want to say that I think Jens has turned out a very nice and professional guide that also explains HOW the circuit works, not just how to put the pieces together.
I think he deserves a lot of credit for donating his layout and his time in creating a manual that is entirely for the benefit of others. Thanks Jens!
EDIT - I started this before your reply Jens. (no changes)
I think he deserves a lot of credit for donating his layout and his time in creating a manual that is entirely for the benefit of others. Thanks Jens!
EDIT - I started this before your reply Jens. (no changes)
I got my board working today...just implemented the jumpers correctly and it's all cool. Works great. I learned a load on this project and I'll have these for all ype of protyping in the future.
Very cool.
Some stuff I don't understand is the Frequency 1 and Frequency 2 thing.
The situation I faced yesterday was definitely oscillation. Without the correct jumper settings, the low pass section was just sitting there without input and ramping itself up to infinity.
I get most of it now.
Thanks TiRoth!
Very cool.
Some stuff I don't understand is the Frequency 1 and Frequency 2 thing.
The situation I faced yesterday was definitely oscillation. Without the correct jumper settings, the low pass section was just sitting there without input and ramping itself up to infinity.
I get most of it now.
Thanks TiRoth!
I would like to thank everybody for their help on this project and beg a few more questions...
I am sure that I could ask this in another forum but would prefer the considered scientific based response as opposed to "vanilla trebel and heavy murky bass with a broadened sound stage, yet not tiring" thing.
Q1. What do you commonly use for hook-up wire for line level applications, for example, from MOX to RCA's in an enclosure? I have been stripping out some old IBM plenum twin ax cable (Belden 89207) and then using the center conductors. They are teflon 20 AWG... one solder coat one bare copper.
Q2. Does it make sense to build a fabricate a small aluminum "fence" between the power supply portion (torroids) of the enclosure and the MOX boards?
Q3 Can any of you hear the difference betwwen a Q or .7 and a Q of 1? (For example) Is this something one should expect to be able to discern? It seems pretty subtle to me...
Peace/Out
I am sure that I could ask this in another forum but would prefer the considered scientific based response as opposed to "vanilla trebel and heavy murky bass with a broadened sound stage, yet not tiring" thing.
Q1. What do you commonly use for hook-up wire for line level applications, for example, from MOX to RCA's in an enclosure? I have been stripping out some old IBM plenum twin ax cable (Belden 89207) and then using the center conductors. They are teflon 20 AWG... one solder coat one bare copper.
Q2. Does it make sense to build a fabricate a small aluminum "fence" between the power supply portion (torroids) of the enclosure and the MOX boards?
Q3 Can any of you hear the difference betwwen a Q or .7 and a Q of 1? (For example) Is this something one should expect to be able to discern? It seems pretty subtle to me...
Peace/Out
Q1
As long you have short connections (sic) almost any wire will do. Miniature coax may actually have unwanted high capacitance. If unshielded, within an enclosure, twist signal and return ("ground") wires for some cancellation effect and run the wire along the bottom/side of the enclosure - the enclosure will provide some shielding. Separate the different channels by space (a few cm) or, if they must cross, cross at right angle.
I admit though that I often violate one or more of these rules due to practical constraints.
Q2
Can help in theory, but I believe effects will be minor. If you build a fence, build it from iron not alu - alu will not shield magnetic fields. Say you could cut up and flatten a tin can, those are easy to cut to dimensions and to bend. But space beats shielding - 10 more cm distance to the transformer likely beats a lovingly constructed fence...
Q3
Q 0.7 to Q 1.0 should make quite a difference. But the audibility depends on frequency. Below 200 Hz, it should become very audible, with the Q 1.0 creating substantial bumps in the frequency response. It should sound more boomy. Of course you will hear that only if you play frequencies in the crossover vicinity.
At higher frequencies (especially >1000 Hz), the room interaction with the speakers creates many sharp peaks and dips in the in-room frequency response, and a difference in Q may not immediately jump to your ears...
I often noticed that the first few seconds of listening - first impression - give the best information. After that, my ears immediately adapt to the new "deformed" spectrum and I make myself believe that it sounds the "same".... In other words, the more "critical" the listening, the more one becomes blind to the obvious and concentrates on minor details ;-)
MBK
As long you have short connections (sic) almost any wire will do. Miniature coax may actually have unwanted high capacitance. If unshielded, within an enclosure, twist signal and return ("ground") wires for some cancellation effect and run the wire along the bottom/side of the enclosure - the enclosure will provide some shielding. Separate the different channels by space (a few cm) or, if they must cross, cross at right angle.
I admit though that I often violate one or more of these rules due to practical constraints.
Q2
Can help in theory, but I believe effects will be minor. If you build a fence, build it from iron not alu - alu will not shield magnetic fields. Say you could cut up and flatten a tin can, those are easy to cut to dimensions and to bend. But space beats shielding - 10 more cm distance to the transformer likely beats a lovingly constructed fence...
Q3
Q 0.7 to Q 1.0 should make quite a difference. But the audibility depends on frequency. Below 200 Hz, it should become very audible, with the Q 1.0 creating substantial bumps in the frequency response. It should sound more boomy. Of course you will hear that only if you play frequencies in the crossover vicinity.
At higher frequencies (especially >1000 Hz), the room interaction with the speakers creates many sharp peaks and dips in the in-room frequency response, and a difference in Q may not immediately jump to your ears...
I often noticed that the first few seconds of listening - first impression - give the best information. After that, my ears immediately adapt to the new "deformed" spectrum and I make myself believe that it sounds the "same".... In other words, the more "critical" the listening, the more one becomes blind to the obvious and concentrates on minor details ;-)
MBK
On an entirely different note, I needed some smaller crossover boards (3"/75mm square) to fit in a tight spot, so I made up a reduced version of Jen's active filter one. It's basically 2.5 MOX boards, two parametric EQs, and a power supply squished into a tiny board. The tradeoff is that it isn't configurable like the MOX -- I use a pair of MOX with some gainclones to proto and then build up on the tiny boards.
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