no where run to nowhere to hide.
'Yeah, I'm sticking to my estimates, barring further information from Nelson. "
Wouldn't it be easier to go read one of the many references on active filters and learn something. The Qs that moamp posted are for the classic filter alignments like the Butterworth odd order and the L-R 2nd and 4th order filters. Moamp posted Spice curves to back up his statements. Why do I have this feeling that you will waiting for Nelson for some time. He didn't adopt you or something did he? Did you save his live and he owes you an eternal debt or what? When you get tired of waiting, go to:
http://beis.de/Elektronik/Filter/ActiveLPFilter.html#Parameter
http://www.linkwitzlab.com/filters.htm#2
http://www.linkwitzlab.com/filters.htm#3
and learn what the Q is for Butterworth and Linkwitz-Riley crossovers.
Or you can run and hide, to pout like a small child........ I have never seen anyone try so hard to keep from learning anything when several experienced people are trying so hard to teach you! Suck up your pride and learn to design crossovers like you said you were going to. Sorry to crash your thread. Feel welcome to post in mine.
Fred
'Yeah, I'm sticking to my estimates, barring further information from Nelson. "
Wouldn't it be easier to go read one of the many references on active filters and learn something. The Qs that moamp posted are for the classic filter alignments like the Butterworth odd order and the L-R 2nd and 4th order filters. Moamp posted Spice curves to back up his statements. Why do I have this feeling that you will waiting for Nelson for some time. He didn't adopt you or something did he? Did you save his live and he owes you an eternal debt or what? When you get tired of waiting, go to:
http://beis.de/Elektronik/Filter/ActiveLPFilter.html#Parameter
http://www.linkwitzlab.com/filters.htm#2
http://www.linkwitzlab.com/filters.htm#3
and learn what the Q is for Butterworth and Linkwitz-Riley crossovers.
Or you can run and hide, to pout like a small child........ I have never seen anyone try so hard to keep from learning anything when several experienced people are trying so hard to teach you! Suck up your pride and learn to design crossovers like you said you were going to. Sorry to crash your thread. Feel welcome to post in mine.
Fred
Attachments
well, considering that Grey has to use the thing I would think it would have buffer/ opamp optons on the board. Notice I said AFTER we find out it works 
I certainly wouldn't mind seeing Fred finish his project to the board layout level also- he's done some good work it seems, but I'm afaid I'm one of those that are too intimidated (he'd say lazy ) to connect the lines on his drawings, but I have to say that his latest posting DOES make the circuit look trivial as Grey says! So at the moment, both projects are living in some imaginary universe. I't will be interesting to see if they are easy/hard to get working perfectly.
HAdn't seen the Borboly ones-good option!
I certainly wouldn't mind seeing Fred finish his project to the board layout level also- he's done some good work it seems, but I'm afaid I'm one of those that are too intimidated (he'd say lazy
) to connect the lines on his drawings, but I have to say that his latest posting DOES make the circuit look trivial as Grey says! So at the moment, both projects are living in some imaginary universe. I't will be interesting to see if they are easy/hard to get working perfectly.HAdn't seen the Borboly ones-good option!
All,
Sorry not to have done much with this thread (or indeed any thread), but life has been...interesting. I've had the flu--still got something, my temperature this afternoon was 97.5 (that's F, not C, obviously). Still, that's a vast improvement over the 103.3 I was running for three or four consecutive days when the bug first bit. Take it from me, this year's version of the flu is a serious butt-kicker. My wife had a head cold for a few days, but got over her germs. While she was down, I was doing nearly all the baby care. Then the baby got sick. Then there was the entertaining evening spent in the emergency room (not me, thank goodness, and yes things are pretty much back to normal there). Just for fun, they changed the operating system on the mainframe here at work which pretty much up-ended the way we've done things for years. In the meantime another story sold, so suddenly I'm on the hotseat trying to get another one ready to go out. Etc.
Ugh.
Then, for the coup de grace, the hard drive in my main PC died. Fortunately, I've got all my current stories on my laptop, but nothing else. Until the laptop is depreciated tax-wise, only writing stuff goes on it so as not to arouse the wrath of the IRS. So I lost a lot of electronics-related things in the process. I don't think it's a head crash--probably the motor. I've spent a bit of time trying to get the drive to come up long enough to get files off of it, but without success. Rats.
Variac,
Boards aren't all that difficult. Really. I lost the files when my C drive croaked. I've located a hardcopy of the 6 dB HP board layout, but will have to download another copy of CIRCAD and install it on whatever I end up using for a C drive, then re-enter the damned layout. All for something that few people will use because I used 2N5457s (single FET, DSG pinout). I've got--somewhere--a couple of 2SK389s that Jam was gracious enough to donate to the cause back a year or two ago. I ran across them when I was doing the big cleanup earlier this fall, but they got submerged again. I think I know where they are, plus-or-minus a foot or two, and will try to come up with a layout for the '389, which as I've said before is a better candidate for this circuit than the 2N5457 anyway. Layout for a circuit this simple isn't a big problem. Or at least it wasn't for the '5457. Single-sided board. The 6dB/oct module is 3.25" x 3.25." The 12dB/oct is 3.25" by about 4 or 4.5." Something like that. Most of that is taken up with resistor choices. If you happen to know what you want for resistance, it can be much smaller. Smaller still if you use a chip. Honestly, given the number of people building chip amps, I anticipated that a lot of people would want to go for the fancy chip opamps available these days. I didn't think that many people would be interested in going discrete. In the long run, it's all to the good, but I got caught off guard.
Ian,
Follower crossovers are easily done. I've had a JFET follower-based Sallen-Key crossover for years. My older active crossover thread was based on exactly that topology. I didn't have adjustable Q in it, which is why I got interested in updating the design. I had no problems with stability, nor have I heard of others having problems. It's nearly universal practice in the tube world, though mine was solid state. It doesn't take a lot of fancy gear to put together a stable follower.
I'm not a big proponent of point-to-point circuits. I've got a JFET (2N5457s again) headamp that's PTP, but that's the exception to the rule; I just did it to prove to myself that a particular topology would do what I wanted. In the long run, I'll be doing a complete phono stage which will be on a PC board. However, that's a ways further down the road. This whole crossover topic gained more momentum than I expected. All I said in the beginning was that I had such a circuit when someone asked if anyone had a JFET input crossover. I added without thinking that I had the board layouts. The 'without thinking' part was my use of the 2N5457 which doesn't allow for easy substitution due to pinout differences. Mea culpa. Given that I've been meaning to redo the layout to accomodate use of 2SK389s, I guess this is the Stereo Gods' way of nudging me along towards a new layout. But I've got to either get a new hard drive or a new computer first. (I'm on a PC at work now [it's a slow night, thank goodness]--if one of these dies, someone pulls a new drive off the shelf and--Hey, presto!--things are back to normal. I don't have pockets as deep as that, especially after having the heat pump crap out six weeks ago.)
Fred,
Back when the XVR1 first came out, I started a thread to notify people that it had appeared on the scene. Somewhere near the beginning of that thread I speculated that the High/Medium/Low Qs were 1, .707, and .5 respectively. Nelson posted shortly afterwards that the gains were 0dB, 3dB, and 6dB. I based my estimates of the XVR1 Q options on back-calculations from Nelson's post. I may have made a math error, but I don't think so.
As for the tone of your post--I expect nothing better coming from someone raised in a barn.
Variac,
Active crossovers really are trivial. It's pretty much a question of putting in numbers and turning the crank. The trick is to make wise choices of crossover points, slopes, and Qs. Unfortunately, that's in the hands of the user.
Fred seems to want to reverse-engineer Nelson's resistor network. If someone wants to go that route, that's fine by me. I look at it more in the manner of a switch-based volume control--how few parts can I put in the signal path? Since the Sallen-Key topology only requires one cap and one resistor per pole, I tried to hold it to that minimum. If, like Fred, you want to get the maximum number of resistance choices in the minimum amount of real estate, then resistor chips would seem to provide a good path for inquiry. To each his own.
Grey
Sorry not to have done much with this thread (or indeed any thread), but life has been...interesting. I've had the flu--still got something, my temperature this afternoon was 97.5 (that's F, not C, obviously). Still, that's a vast improvement over the 103.3 I was running for three or four consecutive days when the bug first bit. Take it from me, this year's version of the flu is a serious butt-kicker. My wife had a head cold for a few days, but got over her germs. While she was down, I was doing nearly all the baby care. Then the baby got sick. Then there was the entertaining evening spent in the emergency room (not me, thank goodness, and yes things are pretty much back to normal there). Just for fun, they changed the operating system on the mainframe here at work which pretty much up-ended the way we've done things for years. In the meantime another story sold, so suddenly I'm on the hotseat trying to get another one ready to go out. Etc.
Ugh.
Then, for the coup de grace, the hard drive in my main PC died. Fortunately, I've got all my current stories on my laptop, but nothing else. Until the laptop is depreciated tax-wise, only writing stuff goes on it so as not to arouse the wrath of the IRS. So I lost a lot of electronics-related things in the process. I don't think it's a head crash--probably the motor. I've spent a bit of time trying to get the drive to come up long enough to get files off of it, but without success. Rats.
Variac,
Boards aren't all that difficult. Really. I lost the files when my C drive croaked. I've located a hardcopy of the 6 dB HP board layout, but will have to download another copy of CIRCAD and install it on whatever I end up using for a C drive, then re-enter the damned layout. All for something that few people will use because I used 2N5457s (single FET, DSG pinout). I've got--somewhere--a couple of 2SK389s that Jam was gracious enough to donate to the cause back a year or two ago. I ran across them when I was doing the big cleanup earlier this fall, but they got submerged again. I think I know where they are, plus-or-minus a foot or two, and will try to come up with a layout for the '389, which as I've said before is a better candidate for this circuit than the 2N5457 anyway. Layout for a circuit this simple isn't a big problem. Or at least it wasn't for the '5457. Single-sided board. The 6dB/oct module is 3.25" x 3.25." The 12dB/oct is 3.25" by about 4 or 4.5." Something like that. Most of that is taken up with resistor choices. If you happen to know what you want for resistance, it can be much smaller. Smaller still if you use a chip. Honestly, given the number of people building chip amps, I anticipated that a lot of people would want to go for the fancy chip opamps available these days. I didn't think that many people would be interested in going discrete. In the long run, it's all to the good, but I got caught off guard.
Ian,
Follower crossovers are easily done. I've had a JFET follower-based Sallen-Key crossover for years. My older active crossover thread was based on exactly that topology. I didn't have adjustable Q in it, which is why I got interested in updating the design. I had no problems with stability, nor have I heard of others having problems. It's nearly universal practice in the tube world, though mine was solid state. It doesn't take a lot of fancy gear to put together a stable follower.
I'm not a big proponent of point-to-point circuits. I've got a JFET (2N5457s again) headamp that's PTP, but that's the exception to the rule; I just did it to prove to myself that a particular topology would do what I wanted. In the long run, I'll be doing a complete phono stage which will be on a PC board. However, that's a ways further down the road. This whole crossover topic gained more momentum than I expected. All I said in the beginning was that I had such a circuit when someone asked if anyone had a JFET input crossover. I added without thinking that I had the board layouts. The 'without thinking' part was my use of the 2N5457 which doesn't allow for easy substitution due to pinout differences. Mea culpa. Given that I've been meaning to redo the layout to accomodate use of 2SK389s, I guess this is the Stereo Gods' way of nudging me along towards a new layout. But I've got to either get a new hard drive or a new computer first. (I'm on a PC at work now [it's a slow night, thank goodness]--if one of these dies, someone pulls a new drive off the shelf and--Hey, presto!--things are back to normal. I don't have pockets as deep as that, especially after having the heat pump crap out six weeks ago.)
Fred,
Back when the XVR1 first came out, I started a thread to notify people that it had appeared on the scene. Somewhere near the beginning of that thread I speculated that the High/Medium/Low Qs were 1, .707, and .5 respectively. Nelson posted shortly afterwards that the gains were 0dB, 3dB, and 6dB. I based my estimates of the XVR1 Q options on back-calculations from Nelson's post. I may have made a math error, but I don't think so.
As for the tone of your post--I expect nothing better coming from someone raised in a barn.
Variac,
Active crossovers really are trivial. It's pretty much a question of putting in numbers and turning the crank. The trick is to make wise choices of crossover points, slopes, and Qs. Unfortunately, that's in the hands of the user.
Fred seems to want to reverse-engineer Nelson's resistor network. If someone wants to go that route, that's fine by me. I look at it more in the manner of a switch-based volume control--how few parts can I put in the signal path? Since the Sallen-Key topology only requires one cap and one resistor per pole, I tried to hold it to that minimum. If, like Fred, you want to get the maximum number of resistance choices in the minimum amount of real estate, then resistor chips would seem to provide a good path for inquiry. To each his own.
Grey
Grey, beggers can't be choosers, and the xover timetable seems to be a long one, no matter who starts a project. Maybe it's cursed.
I don't think many of us feel entitled to a specific design from you, even if you optimistically thought you could write a book on the subject. I do think a lot of people want a chip amp version rather than discrete.
Anyway, this isn't a high pressure place where people can demand things from others, We newbies from a few years ago remember how you just about carried the forum singlehandedly for quite a while, the point is to make sure it's fun for you too.
Keep after this as you have time- that way Nelson has to come through sooner or later. One of his secrets is that when he publishes something, every wire and component is called out and any bonehead such as myself can copy it.
I don't think many of us feel entitled to a specific design from you, even if you optimistically thought you could write a book on the subject.
I do think a lot of people want a chip amp version rather than discrete. Anyway, this isn't a high pressure place where people can demand things from others, We newbies from a few years ago remember how you just about carried the forum singlehandedly for quite a while, the point is to make sure it's fun for you too.
Keep after this as you have time- that way Nelson has to come through sooner or later.
One of his secrets is that when he publishes something, every wire and component is called out and any bonehead such as myself can copy it.
It's certainly true that everything takes a lot longer than
you estimate. I publicize my intended schedule just to put
some pressure on myself, otherwise I never get stuff done.
The initial design concept contains all the entertainment, and
all the rest is just the key turning in the lock.
(By the way, don't ever pay me in advance for anything.)
As to the design issue of followers versus op amps with gain,
my general preference is followers. Simpler, and less likely
for the user to create an oscillator.
you estimate. I publicize my intended schedule just to put
some pressure on myself, otherwise I never get stuff done.
The initial design concept contains all the entertainment, and
all the rest is just the key turning in the lock.
(By the way, don't ever pay me in advance for anything.)
As to the design issue of followers versus op amps with gain,
my general preference is followers. Simpler, and less likely
for the user to create an oscillator.
I'm going on down to Yasgur's farm I'm going to join in a rock 'n' roll band
You don't have to be raised in a barn to know B.S. when you see it...........
Glad to see you are still alive and kicking. We were worried about you. First off, Moamps actually is the one who appears to have reverse engineered the Passlabs resistor matrix and Qs. I came up with a different matrix in an effort to have a greater number of evenly spaced steps, less resistors, and a simpler PCB layout. The cost being two jumpers with 5 positions each. I wanted to use a reasonable number of resistors to allow the use of possibly higher quality resistors than available in most R packs. Minimizing the number of resistors in series was also a goal; worst case is 7 resistors and typically only 3 to 5 are in series. For the very particular about passive component sonics, a fixed value resistor can be soldered across R9 after the appropriate value is determined. Also a pot can be soldered R9 for easy tuning. You would be much better off using the 2SK170 than the 2SK389 for simple jfet followers. Go price them and you will see why.
A gain of 3 dB corresponds to a Q of 0.64 and is a transitional Thomson-Butterworth filter. It is a compromise between a Bessel and a classic flattest amplitude Butterworth alignment and would be an excellent choice. Further tuning of Q is possible with the mismatch of the R and or C values in the second order filter sections. For the design of a Butterworth filter using only followers: http://beis.de/Elektronik/Filter/ActiveLPFilter.html#Parameter It doesn't have a crank, but I think you will figure it out.
"Active crossovers really are trivial. It's pretty much a question of putting in numbers and turning the crank." I cannot agree with this at all! The whole rational for an adjustable crossover is to optimize a crossover for a particular set of drivers. The natural roll off, polar response, and relative position of the drivers becomes in integral part of the crossover slope. Vance Dickason's book: Loudspeaker Recipes: Book 1: Four Two-Way Systems discusses this in detail.
http://www.amazon.com/exec/obidos/tg/detail/-/1882580044/102-1482039-7848945?v=glance
Once more I apologize for intruding in your thread. You raised several technical issues that were worth discussion. I do miss the old days when you would have had the backbone to call me a swine outright instead of the wimpy barnyard reference. BTW, my wife grew up on a farm and has the nicest manners you will ever run across.
You don't have to be raised in a barn to know B.S. when you see it...........
Glad to see you are still alive and kicking. We were worried about you. First off, Moamps actually is the one who appears to have reverse engineered the Passlabs resistor matrix and Qs. I came up with a different matrix in an effort to have a greater number of evenly spaced steps, less resistors, and a simpler PCB layout. The cost being two jumpers with 5 positions each. I wanted to use a reasonable number of resistors to allow the use of possibly higher quality resistors than available in most R packs. Minimizing the number of resistors in series was also a goal; worst case is 7 resistors and typically only 3 to 5 are in series. For the very particular about passive component sonics, a fixed value resistor can be soldered across R9 after the appropriate value is determined. Also a pot can be soldered R9 for easy tuning. You would be much better off using the 2SK170 than the 2SK389 for simple jfet followers. Go price them and you will see why.
A gain of 3 dB corresponds to a Q of 0.64 and is a transitional Thomson-Butterworth filter. It is a compromise between a Bessel and a classic flattest amplitude Butterworth alignment and would be an excellent choice. Further tuning of Q is possible with the mismatch of the R and or C values in the second order filter sections. For the design of a Butterworth filter using only followers: http://beis.de/Elektronik/Filter/ActiveLPFilter.html#Parameter It doesn't have a crank, but I think you will figure it out.
"Active crossovers really are trivial. It's pretty much a question of putting in numbers and turning the crank." I cannot agree with this at all! The whole rational for an adjustable crossover is to optimize a crossover for a particular set of drivers. The natural roll off, polar response, and relative position of the drivers becomes in integral part of the crossover slope. Vance Dickason's book: Loudspeaker Recipes: Book 1: Four Two-Way Systems discusses this in detail.
http://www.amazon.com/exec/obidos/tg/detail/-/1882580044/102-1482039-7848945?v=glance
Once more I apologize for intruding in your thread. You raised several technical issues that were worth discussion. I do miss the old days when you would have had the backbone to call me a swine outright instead of the wimpy barnyard reference. BTW, my wife grew up on a farm and has the nicest manners you will ever run across.
Attachments
My head hurts & I am now confused.
Dear All,
I came to work happy as Larry, with my whole life worked out.
I was going to build a new 3-way actively crossed over speaker system (low WAF, but good Value For Money!).
I was going to build an Aleph 30 or 60 (to run the midrage driver), choosing which one today on the basis of cost of parts/size of heatsinks and transformers; and with the left-over bits make a Balanced Aleph-Mini. The woofer would be looked after by my old Denon.
And build a Balanced Zen Line Stage, which by all accounts is an excellent device with good sound and lots of advantages when combined with the Balanced Alephs. I had even imagined having the crossover board in the BZLS case, as done by another contributor (can't remember his name.)
Join it up with an Active Crossover, based initially on a "cheap" kit over here from Jaycar (Linkwitz-Reily 4th order morphology; based on TL074 opamps ... $88AUS for the kit excluding transformers and case) ... a bargain, but not "balanced". (Upgrade to individual components once more guidance available from the gurus on this board.)
All I had to do was work out:
a) whether it was worth while, or
b) whether it is possible to join up my gleaming, imaginary system
with balanced connections.
I knew about this thread, and searched it out believing "all would be revealed" but now all I am is confused. and depressed
*************
So the questions now are:
1.) Is it worth the hassle? Are there advantages in keeping the system balanced throughout?
2.) If it is worth the hassle, are there any published solutions or pointers on how to make a balanced crossover.
3.) If not fully published then could someone walk me through this diagram please:
http://www.diyaudio.com/forums/attachment.php?s=&postid=271732 (Posted by Uli as SK_Bal.jpg ealier in this thread.
4.) If I went for unbalanced, is the BZLS is still the pre-amp of choice?
5.) I found at Elliott Sound Products a circuit which converts balanced to unbalanced connects. If I were to use this, I imagine that it would be best to keep the crossover as close to the power amp as possible ...
viz.
BZLS ---------------------------------ConvertToUnbalanced-Crossover-Amp (number of dashes indicative of length of connects?
5. If I went unbalanced, then I guess that I wouldn't have to build the Aleph Mini with balanced inputs. Should I consider not putting the "balanced" front end on the Aleph30/60?
I would appreciate some Xenlightenment please.
Regards,
George.
P.S. Now I am even more depressed ... the situation is Beslan has resolved with terrible death toll of innocent children and adults, and just now, I hear that the Australian Embassy in Jakarta has been bombed. I hope this is not true. I will check this out on the news when I get home. Human beings really are a horrifying blend of the best and worst imaginable traits.
Dear All,
I came to work happy as Larry,
with my whole life worked out.I was going to build a new 3-way actively crossed over speaker system (low WAF, but good Value For Money!).
I was going to build an Aleph 30 or 60 (to run the midrage driver), choosing which one today on the basis of cost of parts/size of heatsinks and transformers; and with the left-over bits make a Balanced Aleph-Mini. The woofer would be looked after by my old Denon.
And build a Balanced Zen Line Stage, which by all accounts is an excellent device with good sound and lots of advantages when combined with the Balanced Alephs. I had even imagined having the crossover board in the BZLS case, as done by another contributor (can't remember his name.)
Join it up with an Active Crossover, based initially on a "cheap" kit over here from Jaycar (Linkwitz-Reily 4th order morphology; based on TL074 opamps ... $88AUS for the kit excluding transformers and case) ... a bargain, but not "balanced". (Upgrade to individual components once more guidance available from the gurus on this board.)
All I had to do was work out:
a) whether it was worth while, or
b) whether it is possible to join up my gleaming, imaginary system
with balanced connections.
I knew about this thread, and searched it out believing "all would be revealed" but now all I am is confused.
and depressed *************
So the questions now are:
1.) Is it worth the hassle? Are there advantages in keeping the system balanced throughout?
2.) If it is worth the hassle, are there any published solutions or pointers on how to make a balanced crossover.
3.) If not fully published then could someone walk me through this diagram please:
http://www.diyaudio.com/forums/attachment.php?s=&postid=271732 (Posted by Uli as SK_Bal.jpg ealier in this thread.
4.) If I went for unbalanced, is the BZLS is still the pre-amp of choice?
5.) I found at Elliott Sound Products a circuit which converts balanced to unbalanced connects. If I were to use this, I imagine that it would be best to keep the crossover as close to the power amp as possible ...
viz.
BZLS ---------------------------------ConvertToUnbalanced-Crossover-Amp (number of dashes indicative of length of connects?
5. If I went unbalanced, then I guess that I wouldn't have to build the Aleph Mini with balanced inputs. Should I consider not putting the "balanced" front end on the Aleph30/60?
I would appreciate some Xenlightenment please.
Regards,
George.
P.S. Now I am even more depressed ... the situation is Beslan has resolved with terrible death toll of innocent children and adults, and just now, I hear that the Australian Embassy in Jakarta has been bombed. I hope this is not true. I will check this out on the news when I get home. Human beings really are a horrifying blend of the best and worst imaginable traits.
George,
I understand your frustration.
Its appears you are contending & dwelling on lots of issues, they will mostly sort out when you get started.
Can I recommend to you that you just start with building up the Aleph 30 amps (Aleph 30...nice for midrange) as the 1st phase of your project and build them for balanced mode.
Its bomb proof and plenty of members have made boards and can offer assistance and a great 1st amp. That said I also like the Zen but not as WAF friendly.
For a recipe see Wayne Sankey's page in the Passdiy.com gallery or Mark Finnis excellent pages also there to get you started.
I am also local and currenlty building a High Low Pass crossover project.
You are welcome to write me for assistance.
macka
I understand your frustration.
Its appears you are contending & dwelling on lots of issues, they will mostly sort out when you get started.
Can I recommend to you that you just start with building up the Aleph 30 amps (Aleph 30...nice for midrange) as the 1st phase of your project and build them for balanced mode.
Its bomb proof and plenty of members have made boards and can offer assistance and a great 1st amp. That said I also like the Zen but not as WAF friendly.
For a recipe see Wayne Sankey's page in the Passdiy.com gallery or Mark Finnis excellent pages also there to get you started.
I am also local and currenlty building a High Low Pass crossover project.
You are welcome to write me for assistance.
macka
Sanity break
Thanks to Macka and Nelson for the advice.
The sun is warm and the ocean beckons for a little dip.
The information on the Jakarta bombing has started filtering through. No Embassy staff killed or injured. At least 6 local people killed on the street, >100 injured. Major structural damage to two adjacent buildings to 15 or more storeys. (I know that my worries fade into insignificance in a humanity-wide frame of reference.)
Regards,
George.
Thanks to Macka and Nelson for the advice.
The sun is warm and the ocean beckons for a little dip.
The information on the Jakarta bombing has started filtering through. No Embassy staff killed or injured. At least 6 local people killed on the street, >100 injured. Major structural damage to two adjacent buildings to 15 or more storeys. (I know that my worries fade into insignificance in a humanity-wide frame of reference.)
Regards,
George.
PASS XVR1 X-over & drivers - an understanding question
I'm not quite sure this is the right thread to ask this, but...
Recently I purchased a second hand XVR1 from PASS (a long lasting dream). Now I can move a 3 way loudspeaker with passive xover to an active one. Here is my question - and it is mainly an understanding issue - i reckon.
The drivers are - according to specs at 0db
bass 30hz to 2000hz,
medium from 500hz to 10khz
tweeter is 4kHz to 35kHz
My question : shall I set the XVR1 for the bass from say 0 to 500hz, then have the medium to go from 500Hz to 5000Hz and the tweeter from 5000Hz ?
Or shall I set the XVR1 for the bass from say 0hz to 1500hz, the have the medium to go from 1500hz to 8000hz and the tweeter as of 8000hz ?
Basicaly my question is : how to determine the best cross over combination. Is it simply by listening / measuring or is there a 'correct' approach ? As there litterature or software available to help ?
Thanks for your support / comments / suggestions
I'm not quite sure this is the right thread to ask this, but...
Recently I purchased a second hand XVR1 from PASS (a long lasting dream). Now I can move a 3 way loudspeaker with passive xover to an active one. Here is my question - and it is mainly an understanding issue - i reckon.
The drivers are - according to specs at 0db
bass 30hz to 2000hz,
medium from 500hz to 10khz
tweeter is 4kHz to 35kHz
My question : shall I set the XVR1 for the bass from say 0 to 500hz, then have the medium to go from 500Hz to 5000Hz and the tweeter from 5000Hz ?
Or shall I set the XVR1 for the bass from say 0hz to 1500hz, the have the medium to go from 1500hz to 8000hz and the tweeter as of 8000hz ?
Basicaly my question is : how to determine the best cross over combination. Is it simply by listening / measuring or is there a 'correct' approach ? As there litterature or software available to help ?
Thanks for your support / comments / suggestions
If you have the manual (get it at www.passlabs.com if you don't)
then I suggest reading the section about philosophy of adjusting
crossovers.
It's usually a pretty tedious process, best undertaken over
months. It is very helpful, but not required, to have some sort
of response measuring equipment to help guide you through the
process.
then I suggest reading the section about philosophy of adjusting
crossovers.
It's usually a pretty tedious process, best undertaken over
months. It is very helpful, but not required, to have some sort
of response measuring equipment to help guide you through the
process.
Unfortunately, there is no easy way to set crossover points and levels. Anyone who tells you otherwise is...well...misinformed.
The first thing you run into is hopelessly optimistic specifications for drivers. For instance, I'd suggest that 2kHz as a usable top end from a woofer is just not realistic. Either that figure or the 30Hz figure for the low end (or both) are simply not going to work out. It's a cold cruel world and you're likely to find that the 30Hz lower limit is closer to 50Hz, perhaps even as high as 70Hz if you measure it.
The second problem is room interactions.
The third problem is test equipment (or lack of same).
In the final analysis most people are so happy that any sound comes out at all that they tend to dial in some pretty random settings and settle in to listen. After a month or so, the listener has grown so used to that balance that they tell themselves that it's 'right.'
If you're looking for a starting point, I'd suggest beginning with, say, 500Hz crossover between the woofer and the midrange, and 5kHz between the midrange and the tweeter. Don't be surprised if you find that the final crossover points vary an octave or so from these starting points.
If I read your post correctly, you've only bought one XVR1. That will only allow you to biamp, not triamp. If that is indeed the case, you'll need a passive crossover for the other crossover point. As a general rule, you'll get the best results when running the mid/tweeter as a pair and the woofer by itself. Going from biamping to triamping will yield less subjective improvement than the jump from single amp to biamping. I have a quad amp setup and there's just not that much benefit, except in flexibility. Sonics aren't that much better than triamping.
A quick trick to rough-set the relative levels between two drivers: Play a test tone set to the crossover frequency at low volume. Hold your head between the two drivers and adjust until they sound equally loud. Fine tune as necessary.
Don't kid yourself. It's a lot of work. But if you do it properly, it will give you splendid results.
Grey
The first thing you run into is hopelessly optimistic specifications for drivers. For instance, I'd suggest that 2kHz as a usable top end from a woofer is just not realistic. Either that figure or the 30Hz figure for the low end (or both) are simply not going to work out. It's a cold cruel world and you're likely to find that the 30Hz lower limit is closer to 50Hz, perhaps even as high as 70Hz if you measure it.
The second problem is room interactions.
The third problem is test equipment (or lack of same).
In the final analysis most people are so happy that any sound comes out at all that they tend to dial in some pretty random settings and settle in to listen. After a month or so, the listener has grown so used to that balance that they tell themselves that it's 'right.'
If you're looking for a starting point, I'd suggest beginning with, say, 500Hz crossover between the woofer and the midrange, and 5kHz between the midrange and the tweeter. Don't be surprised if you find that the final crossover points vary an octave or so from these starting points.
If I read your post correctly, you've only bought one XVR1. That will only allow you to biamp, not triamp. If that is indeed the case, you'll need a passive crossover for the other crossover point. As a general rule, you'll get the best results when running the mid/tweeter as a pair and the woofer by itself. Going from biamping to triamping will yield less subjective improvement than the jump from single amp to biamping. I have a quad amp setup and there's just not that much benefit, except in flexibility. Sonics aren't that much better than triamping.
A quick trick to rough-set the relative levels between two drivers: Play a test tone set to the crossover frequency at low volume. Hold your head between the two drivers and adjust until they sound equally loud. Fine tune as necessary.
Don't kid yourself. It's a lot of work. But if you do it properly, it will give you splendid results.
Grey
CROSSOVER advises
Thanks to GRollins and Nelson Pass. One small additionnal question : loudspeaker specs indicate a bottom and top frequencie as well as a crossover frequency. For example the mid range has a frequency from 500hz to 10kHz and a recommended crossover at 800hz. Why is that ? Why is there only one cross over at the bottom end ? So what is the crossover frequency for ?
GRollins you're right mid / Tweeter is passive for the while
GRollins said:
Thanks to GRollins and Nelson Pass. One small additionnal question : loudspeaker specs indicate a bottom and top frequencie as well as a crossover frequency. For example the mid range has a frequency from 500hz to 10kHz and a recommended crossover at 800hz. Why is that ? Why is there only one cross over at the bottom end ? So what is the crossover frequency for ?
GRollins you're right mid / Tweeter is passive for the while
This is one of the things that makes life interesting. The crossover gives the driver in question a tailored signal. If, for instance, you have a low pass filter at 500Hz, then the signal is assumed to rolloff at a nice, predictable 12dB/oct below that.
So far, so good.
But...
(You knew it couldn't be that simple.)
Supposing the driver is also rolling off at, let's say, 6dB/oct in that same frequency range. What happens to your 12dB/oct crossover slope? The two slopes are additive. Where you thought you had a 12dB/oct slope, you now find that you have an 18dB/oct slope.
Uh oh.
This is why you can't just thow speakers together based on specs and expect it to work perfectly the first time around. If it were that simple, everybody would buy a handful of drivers, cut holes in boxes, and have the functional equivalent of a WAMM or whatever is cool this month.
To get the driver response to behave the way you expect it to, the driver needs to have flat response for at least an octave or three past the crossover point. The lower the slope, the longer you need the driver to remain flat. Sharper slopes need less room to do their stuff.
In your case, having a driver that indicates it's flat to 500Hz with a recommended crossover point of 800Hz is the manufacturer's way of hinting that you need to give the crossover time to work.
Dollars to doughnuts, that driver isn't really flat down to 500Hz. I'd just about bet you money that the thing is already rolling off above that. So what do you do? Let's pretend that it's rolling off at about 6dB/oct and your target slope is 12dB/oct. Do you use a 12dB/oct slope? Nope...that would give you an 18dB/oct slope in the real world. Instead, you set the XVR1 for a 6dB/oct slope that would combine with the driver's natural rolloff of 6dB/oct to give the desired 12dB/oct slope. Then you play with the crossover point and Q to fine tune the response.
Grey
So far, so good.
But...
(You knew it couldn't be that simple.)
Supposing the driver is also rolling off at, let's say, 6dB/oct in that same frequency range. What happens to your 12dB/oct crossover slope? The two slopes are additive. Where you thought you had a 12dB/oct slope, you now find that you have an 18dB/oct slope.
Uh oh.
This is why you can't just thow speakers together based on specs and expect it to work perfectly the first time around. If it were that simple, everybody would buy a handful of drivers, cut holes in boxes, and have the functional equivalent of a WAMM or whatever is cool this month.
To get the driver response to behave the way you expect it to, the driver needs to have flat response for at least an octave or three past the crossover point. The lower the slope, the longer you need the driver to remain flat. Sharper slopes need less room to do their stuff.
In your case, having a driver that indicates it's flat to 500Hz with a recommended crossover point of 800Hz is the manufacturer's way of hinting that you need to give the crossover time to work.
Dollars to doughnuts, that driver isn't really flat down to 500Hz. I'd just about bet you money that the thing is already rolling off above that. So what do you do? Let's pretend that it's rolling off at about 6dB/oct and your target slope is 12dB/oct. Do you use a 12dB/oct slope? Nope...that would give you an 18dB/oct slope in the real world. Instead, you set the XVR1 for a 6dB/oct slope that would combine with the driver's natural rolloff of 6dB/oct to give the desired 12dB/oct slope. Then you play with the crossover point and Q to fine tune the response.
Grey
A random assortment of ideas:
1) Minimize the DC, either through design or adjustment
2) Use a fuse
3) Use a cap
4) Use a fancy protection circuit to monitor the DC and shut down the amp if necessary
Note that if you opt for #3, you'll need to allow for the fact that the cap itself creates a first order (i.e. 6dB/oct) slope. Adjust your crossover accordingly. You can approach this from two directions. One, use a really big cap, thus pushing the passive crossover point way down and allowing the active crossover to run the show. Two--and the more elegant method--is to size the cap such that it is actually part of the crossover. You'll have a smaller and cheaper cap. You'll also have wider latitude in choice of parts, since high quality caps are rarely available in larger capacitances.
Grey
1) Minimize the DC, either through design or adjustment
2) Use a fuse
3) Use a cap
4) Use a fancy protection circuit to monitor the DC and shut down the amp if necessary
Note that if you opt for #3, you'll need to allow for the fact that the cap itself creates a first order (i.e. 6dB/oct) slope. Adjust your crossover accordingly. You can approach this from two directions. One, use a really big cap, thus pushing the passive crossover point way down and allowing the active crossover to run the show. Two--and the more elegant method--is to size the cap such that it is actually part of the crossover. You'll have a smaller and cheaper cap. You'll also have wider latitude in choice of parts, since high quality caps are rarely available in larger capacitances.
Grey
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