re crossovers
In a 1976 AES paper Linkwitz pointed out that if the drivers are not in phase through the crossover region, the vertical lobe wanders up and down as you sweep a signal from below to above the crossover frequency, this effect is exacerbated by a high crossover frequency since the lobe is narrowed for higher crossover frequencies. Filters that have this in phase property are Butterworth squared ones.
The avantage of the mtm configuration is that it is psudo coaxial and this lobe wandering does not occur, this allows odd order Butterworth filters to be used these having flat frequency and power responce, the L-R type of filter having only flat frequency responce.
All of this can be greatly affected by the transfer functions of the drivers you are using, a tweeter for instance has low enough residual phase shift for most purposes if it is crossed over at least one octave above its resonant frequency, any closer than this means that the phase is changing at too rapid a rate and effects become audible, "psudo L-R", crossover filters have been developed for this range .
In most cases it is possible to compensate a tweeter for acoustic offset by connecting it the reverse way round, if you are careful about the particular concantenation of transfer functions that you use, Linkwitz uses an all pass filter to achieve time delays.
In general the major hearable effect of acoustic center mismatch can be seen in the frequency responce.
In a 1976 AES paper Linkwitz pointed out that if the drivers are not in phase through the crossover region, the vertical lobe wanders up and down as you sweep a signal from below to above the crossover frequency, this effect is exacerbated by a high crossover frequency since the lobe is narrowed for higher crossover frequencies. Filters that have this in phase property are Butterworth squared ones.
The avantage of the mtm configuration is that it is psudo coaxial and this lobe wandering does not occur, this allows odd order Butterworth filters to be used these having flat frequency and power responce, the L-R type of filter having only flat frequency responce.
All of this can be greatly affected by the transfer functions of the drivers you are using, a tweeter for instance has low enough residual phase shift for most purposes if it is crossed over at least one octave above its resonant frequency, any closer than this means that the phase is changing at too rapid a rate and effects become audible, "psudo L-R", crossover filters have been developed for this range .
In most cases it is possible to compensate a tweeter for acoustic offset by connecting it the reverse way round, if you are careful about the particular concantenation of transfer functions that you use, Linkwitz uses an all pass filter to achieve time delays.
In general the major hearable effect of acoustic center mismatch can be seen in the frequency responce.
Disabled Account
Joined 2003
Hi beady,
There have been MANY comments regarding these speakers. Try searching these forums- I don't think any particular DIY speaker has had THIS much feedback.
If you already have a subwoofer and don't need the generous bass, you could probably build something smaller. Design is often a balance of compromises, and the Response 2.5 is no exception. To get that level of bass the tradeoff was lower than average sensitivity. To get that kind of treble dispersion a 3/4" tweeter was used, and the tradeoff, I believe, (but never confirmed by measurements) is slightly increased tweeter distortion in and around the crossover region (1-4Khz)
The Response 2.5/clone is quite good, but not the LAST speaker you'll build. Trust me on this. 🙂 When I started out I thought, "I better take care coz I don't want to stuffup and have to build another cabinet"
Now I've finished and haven't stuffed up, I HAVE built another. And there's another project coming this Christmas. 🙂
For a excellent value project- may I recommend John Krutke's SEAS All Metal System:
http://www.zaphaudio.com/audio-speaker17.html
Compared to the ProAc 2.5 clone it does everything you'd expect- In only a 14L (0.5 cu ft) cabinet, there's less bass- F3= 50Hz. But you gain higher sensitivity (plays louder with the same watts)
But the best thing is the midrange and treble quality- excellent midrange to treble integration, clearly apparent is any music with singing. I've learnt lyrics that I previously thought were incomprehensible.
Here's the clincher: Half the cost.
addenda
It should also be metiond that the disparity between the on axis and power responce in the 3kHz. crossover region corresponds to the region that when attenuated gives orchestral music a more "real" sound, this is mentioned by Linkwitz on his site and was first noted in BBC research that goes back to the fifties.
This psycoacoustic effect is probably a lot of the the reason why classical music fans go for this type of speaker, and was exploited in such designs as the still current Spendor eight inch two way of the seventies and eighties, crossing over to a 6 inch driver in this region lessens the disparity between the on axis and power responce, and is in genral a better compromise for most people.
It should also be metiond that the disparity between the on axis and power responce in the 3kHz. crossover region corresponds to the region that when attenuated gives orchestral music a more "real" sound, this is mentioned by Linkwitz on his site and was first noted in BBC research that goes back to the fifties.
This psycoacoustic effect is probably a lot of the the reason why classical music fans go for this type of speaker, and was exploited in such designs as the still current Spendor eight inch two way of the seventies and eighties, crossing over to a 6 inch driver in this region lessens the disparity between the on axis and power responce, and is in genral a better compromise for most people.
Tktran is right on...
Build this:
http://www.zaphaudio.com/audio-speaker17.html
And don't torture yourself by debating over all of the choices out there.
See my post here:
http://www.madisound.com/cgi-bin/discuss.cgi?read=351523
And check out the crossovers of the Krutke L18. Very simple, incredibly effective.
If you build it you won't regret it. You can easily convert the cabinet to a small floorstanding design in the 34-40" height range (false lower chamber).
Build this:
http://www.zaphaudio.com/audio-speaker17.html
And don't torture yourself by debating over all of the choices out there.
See my post here:
http://www.madisound.com/cgi-bin/discuss.cgi?read=351523
And check out the crossovers of the Krutke L18. Very simple, incredibly effective.
If you build it you won't regret it. You can easily convert the cabinet to a small floorstanding design in the 34-40" height range (false lower chamber).
I've got another idea:
Get one of those pocket tool kits and a large jacket. Then head down to a 'hi-end' dealer and get a demo of the most expensive speakers in the shop.
Ask the dealer if you can listen alone and then pull out your trusty tool kit and take those expensive mid & treble units out, then pop the grill covers back on so the idiot behind the counter is non the wiser and simply leave telling him that the mid range and treble seems somewhat rolled off 😉
Et voila! You have expensive drivers to use in you design.
PS. I do this all the time and it works a charm.
Get one of those pocket tool kits and a large jacket. Then head down to a 'hi-end' dealer and get a demo of the most expensive speakers in the shop.
Ask the dealer if you can listen alone and then pull out your trusty tool kit and take those expensive mid & treble units out, then pop the grill covers back on so the idiot behind the counter is non the wiser and simply leave telling him that the mid range and treble seems somewhat rolled off 😉
Et voila! You have expensive drivers to use in you design.
PS. I do this all the time and it works a charm.
Hi there
Asking questions on this forum are always a problem. To many opinions and to few answers. It seems as if the proac 2.5's have fallen out of fashion a bit, so you will have many people that built them when the craze was at a peak now advising to build something else.
I believe that the 2.5 clone is hard to beat as a first project. It is not to difficult to build, and the sound quality is phenominal for the money. IMHO it is one of the speakers with the biggest ratio of DIY cost as opposed to the cost of buying the original.
Just one tip. Build it with Jacq's modified crossover as found on this site:
http://www.geocities.com/diyproac25/
Have fun
Dirk
Asking questions on this forum are always a problem. To many opinions and to few answers. It seems as if the proac 2.5's have fallen out of fashion a bit, so you will have many people that built them when the craze was at a peak now advising to build something else.
I believe that the 2.5 clone is hard to beat as a first project. It is not to difficult to build, and the sound quality is phenominal for the money. IMHO it is one of the speakers with the biggest ratio of DIY cost as opposed to the cost of buying the original.
Just one tip. Build it with Jacq's modified crossover as found on this site:
http://www.geocities.com/diyproac25/
Have fun
Dirk
Disabled Account
Joined 2003
Yeah the clone gets a unfair rap sometimes, because extremely opinionated people like myself can get very vocal. We also dwell on the smallest points. 🙂
Like other speakers it's not perfect, but all in all, it's still a pretty good 2 way. But apart from the great sound, I think the 2 main reasons that it's so popular is that it's got the backing of a "high-end" brand, with an equally "high-end" pricetag.
When I was ready to build more speakers after the first I sent an email to the owner of DIY ProAc Response 2.5, and said something to the effect of "Ok, I'm ready. I've had a taste of the good stuff, and I want more! Where to next?!"
Tony Gee was the answer. Now although you hardly hear of Tony's designs over on these English speaker forums, it's not hard to see why or how some of his designs are in an entirely different league.
I was tempted to follow build a true heavyweight- the Soup, an Avalon Acoustics Opus Ceramique clone.
There are many other speakers, designed by experienced DIYers, all from the ground up, that could outdo the clone. But they often do not get a closer look because they are missing the "high end for little money" appeal of the ProAc clone.
For me, the $1,000 question is whether I can build a speaker with a)a smaller or easier cabinet b) qualities similar to, or better than the clone, for C) less money.
Troels answered this with his own TJL.
IMHO this is not a matter of fashion. This is a matter of learning and wanting to improve.
But today, the question is "DIY Audiophile 2-way with drivers ~$350".
I own both the 2.95 and John Krutke SEAS All Metal System. The latter costs $200 in drivers, which is half of the clone. And they are not better in abolute terms- You will lose some bass.
But this actually might not be a disadvantage if a) you already own a subwoofer b) have a smaller room or c) require closer to wall placement.
The other downside I can think of is this: they're darn revealing speakers- too honest in fact- if you feed them bad recordings you will hear bad recordings...
Like other speakers it's not perfect, but all in all, it's still a pretty good 2 way. But apart from the great sound, I think the 2 main reasons that it's so popular is that it's got the backing of a "high-end" brand, with an equally "high-end" pricetag.
When I was ready to build more speakers after the first I sent an email to the owner of DIY ProAc Response 2.5, and said something to the effect of "Ok, I'm ready. I've had a taste of the good stuff, and I want more! Where to next?!"
Tony Gee was the answer. Now although you hardly hear of Tony's designs over on these English speaker forums, it's not hard to see why or how some of his designs are in an entirely different league.
I was tempted to follow build a true heavyweight- the Soup, an Avalon Acoustics Opus Ceramique clone.
There are many other speakers, designed by experienced DIYers, all from the ground up, that could outdo the clone. But they often do not get a closer look because they are missing the "high end for little money" appeal of the ProAc clone.
For me, the $1,000 question is whether I can build a speaker with a)a smaller or easier cabinet b) qualities similar to, or better than the clone, for C) less money.
Troels answered this with his own TJL.
IMHO this is not a matter of fashion. This is a matter of learning and wanting to improve.
But today, the question is "DIY Audiophile 2-way with drivers ~$350".
I own both the 2.95 and John Krutke SEAS All Metal System. The latter costs $200 in drivers, which is half of the clone. And they are not better in abolute terms- You will lose some bass.
But this actually might not be a disadvantage if a) you already own a subwoofer b) have a smaller room or c) require closer to wall placement.
The other downside I can think of is this: they're darn revealing speakers- too honest in fact- if you feed them bad recordings you will hear bad recordings...
Hey guys sorry to bump up an old thread but, wondering really if the Dayton RS180 would be a workable drop in for the L18....to make the cost of the design even lower.....
I've heard alot of people say that the L18 and Dayton RS180 were very similar, but i wondered if they were similar enough to be used in drop in situations.....And if Krutke's xover design would work well with the Dayton as well.....Would be ~$120 in drivers if thast the case...very affordable and simple xover design as well.
Any ideas on what you guys spent for the xover parts and such?
I've heard alot of people say that the L18 and Dayton RS180 were very similar, but i wondered if they were similar enough to be used in drop in situations.....And if Krutke's xover design would work well with the Dayton as well.....Would be ~$120 in drivers if thast the case...very affordable and simple xover design as well.
Any ideas on what you guys spent for the xover parts and such?
Unfortunately, the two drivers have many differences that are made up for in the crossover.
As I understand it, the Seas unit has a more concentrated breakup frequency that can be filtered out in a different manner than is required for the Dayton woofer. The Dayton woofer just goes south over 4 khz; all frequency input that high causing loud ugly breakup.
I read your other post, and I have a suggestion for where you can find a design to try with the RS180-
http://htguide.com/forum/showthread.php4?t=13154
This design uses the RS180 with the Seas 27tdfc. The seas H1212 should be basically a drop-in replacement.
Joe
As I understand it, the Seas unit has a more concentrated breakup frequency that can be filtered out in a different manner than is required for the Dayton woofer. The Dayton woofer just goes south over 4 khz; all frequency input that high causing loud ugly breakup.
I read your other post, and I have a suggestion for where you can find a design to try with the RS180-
http://htguide.com/forum/showthread.php4?t=13154
This design uses the RS180 with the Seas 27tdfc. The seas H1212 should be basically a drop-in replacement.
Joe
Spend the money on the Seas
The Krutke design has a simple crossover - the money saved will allow you to spring for the extra money on the Seas L18, which is really, really good.
The Krutke design has a simple crossover - the money saved will allow you to spring for the extra money on the Seas L18, which is really, really good.
Howdy beady,
Disclaimer first - I havn't listed to this construction
...but being a fan of the NEO3 I would give the Zircon some consideration.
http://www.lonesaguaro.com/speakers/zircon/zircon.htm
At $150 a piece they would not stress your budget
Disclaimer first - I havn't listed to this construction
...but being a fan of the NEO3 I would give the Zircon some consideration.
http://www.lonesaguaro.com/speakers/zircon/zircon.htm
At $150 a piece they would not stress your budget
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