Here's the deal:
I have a set of MTM's that I built a few years back when I didn't know quite what I know now about speaker building. I find myself not listening to my system much anymore for music, because it just sounds flat and lifeless to me. The midrange on these MTM's is good, and the sweet spot is nice, but I notice some combing effect, and it's driving me crazy! the bass is also lacking- especially the midbass. They sound too thin. I have come to the conclusion that I will leave this setup for my video / home theater, and build something else. I am under the impression that an augmented full range system would be my best bet- with a fullrange driver covering the critical 100-5kHz region, augmented by a tweeter of some sort, and a woofer on the bottom (possibly a TL?) Biamping or triamping is defenitely an option.
This is the idea I had in mind, but I am basically open to any suggestions... I NEED HELP FINDING MUSICAL NIRVANA! I really want to enjoy my system again. I am on somewhat of a budget, but it's not severe- more or less nothing super exotic, but I will consider all options. Let me know what you all think, if you don't mind. TIA.
Steve
I have a set of MTM's that I built a few years back when I didn't know quite what I know now about speaker building. I find myself not listening to my system much anymore for music, because it just sounds flat and lifeless to me. The midrange on these MTM's is good, and the sweet spot is nice, but I notice some combing effect, and it's driving me crazy! the bass is also lacking- especially the midbass. They sound too thin. I have come to the conclusion that I will leave this setup for my video / home theater, and build something else. I am under the impression that an augmented full range system would be my best bet- with a fullrange driver covering the critical 100-5kHz region, augmented by a tweeter of some sort, and a woofer on the bottom (possibly a TL?) Biamping or triamping is defenitely an option.
This is the idea I had in mind, but I am basically open to any suggestions... I NEED HELP FINDING MUSICAL NIRVANA! I really want to enjoy my system again. I am on somewhat of a budget, but it's not severe- more or less nothing super exotic, but I will consider all options. Let me know what you all think, if you don't mind. TIA.
Steve
SY said:
Not quite sure what you mean there...
Are you talking bafflestep?
I had the crossover designed by madisound. The design is as follows:
two Vifa P17WJ's paralleled, and a Morel MDT-33 tweeter. The design looks pretty textbook- simple 2nd order @2200Hz with impedance compensation on the woofers. I think I went wrong by putting them in very narrow tower cabinets and tuning them lower for extension. Plus, for some unknown reason, the ports are high on the front of the cabinet, so there is not much floor reinforcement going on there, and little backwall reinforcement. I think the combination killed my upper bass and lower mids. The spacing on the MTM arrangement is fairly tight- both woofers hugging the tweeter. I still think the seperation of the woofers is causing some wierdness in the midrange. When you're in the sweet spot, they image unbelievably well. So well that they put a lot of speakers in the $1200- $2000 range to shame. The problems are with the weak midbass, which makes them sound very forward, and with the slight combing effect (which I will admit I am somewhat more sensitive about than other people). I was thinking of rebuilding them in wider cabinets with a more standard tuning in a standard MMT arrangement. What do you think?
Well, if you're using a cabinet that's narrower than the designer of the xover assumed, yeah, you'll get some mid-bass weakness. A simple thing to try is a passive RC eq circuit between pre and power amps. You can do the spreading loss (or baffle step, if you prefer) compensation electronically and it may save you some wood-cutting.
One more thing- with that driver combo, I'd be mightly tempted to go for an acoustic 4th L-R xover. These are some good drivers and a little bit of care can make them really sing.
When you say "combin," do you mean side-to-side or up-and-down?
One more thing- with that driver combo, I'd be mightly tempted to go for an acoustic 4th L-R xover. These are some good drivers and a little bit of care can make them really sing.
When you say "combin," do you mean side-to-side or up-and-down?
Many times dull sound comes as a result of poor inductor quality with high DCR and core losses (if any).
Try some low DCR inductors and have all crossover connections soldered.
If the sound is still dull you can also try solid core speaker wire of good cross section.
What type of capacitors do you have on the crossover?
Try some low DCR inductors and have all crossover connections soldered.
If the sound is still dull you can also try solid core speaker wire of good cross section.
What type of capacitors do you have on the crossover?
Sy,
Why would you go for the 4th order L-R? What would the benefits be?
Would you keep the MTM arrangement?
I really do like the tweeter (it is very natural), and I am happy with the midrange clarity I get... I just think I blew it in the cabinet design. Thanks for the suggestions, and please keep them coming. I am definitely open to redesigning what I have. As far as the comb effects go, it is in the horizontal "side to side" plane. Move an inch off the sweet spot, and there is a definite "dead" spot somewhere near or slightly above the crossover frequency. Move a little more and it's normal. It sends me up a wall sometimes!
Apassgear,
I used good quality low esr caps (multiple paralleled on the tweeter with a small value bypass). The inductors are also high quality heavy gage (on the woofer). I used an 18 gage on the tweeter, which is what the design called for (the filter was calculated using this value resistance). They are all perfect lay air core types.
Thanks for the comments... I look forward to hearing more.
Steve
Why would you go for the 4th order L-R? What would the benefits be?
Would you keep the MTM arrangement?
I really do like the tweeter (it is very natural), and I am happy with the midrange clarity I get... I just think I blew it in the cabinet design. Thanks for the suggestions, and please keep them coming. I am definitely open to redesigning what I have. As far as the comb effects go, it is in the horizontal "side to side" plane. Move an inch off the sweet spot, and there is a definite "dead" spot somewhere near or slightly above the crossover frequency. Move a little more and it's normal. It sends me up a wall sometimes!
Apassgear,
I used good quality low esr caps (multiple paralleled on the tweeter with a small value bypass). The inductors are also high quality heavy gage (on the woofer). I used an 18 gage on the tweeter, which is what the design called for (the filter was calculated using this value resistance). They are all perfect lay air core types.
Thanks for the comments... I look forward to hearing more.
Steve
nobody special said:
Runing // midbass speakers the amp will see a low impedance which will call for some heavy amps.
Is your amp capable of supplying the needed power?
Other ideas are that something on the crossover is sucking power, once again, when running low impedance speakers your inductor should be a very low DCR type, I'm speaking of something like 0.02 Ohms maximum cored inductors with no saturation problems.
Of course capacitor are also resposible for power losses.
What type of capacitors are you using?
The 4th LR will give you better control of the polar pattern. Typically, lower distortion and better power handling, too. It tends to be not as sensitive as other types to frequency response errors due to offsets in acoustic center between the drivers.
The caveat is that, as with other xover transfer functions, what you need to shoot for is a acoustic 4th order LR. In general, that will NOT be the same as an electrical 4th order LR, since the drivers contribute their own rolloffs.
MTMs tend to have narrower vertical dispersion than MMTs, but less lobing. That sounds a bit contradictory, but isn't; the rolloffs as you get out of the "beam" tend to be smoother with well-executed MTMs. Try reworking the xover, leaving the wood alone and see if you like that. Easy and reversable stuff first. If the vertical dispersion is still too narrow for your taste, then you can redo the cabinet.
Your combing may be a cabinet diffraction issue. Try some thick felt around the cabinet edges (on the front baffle) and see if that helps.
The caveat is that, as with other xover transfer functions, what you need to shoot for is a acoustic 4th order LR. In general, that will NOT be the same as an electrical 4th order LR, since the drivers contribute their own rolloffs.
MTMs tend to have narrower vertical dispersion than MMTs, but less lobing. That sounds a bit contradictory, but isn't; the rolloffs as you get out of the "beam" tend to be smoother with well-executed MTMs. Try reworking the xover, leaving the wood alone and see if you like that. Easy and reversable stuff first. If the vertical dispersion is still too narrow for your taste, then you can redo the cabinet.
Your combing may be a cabinet diffraction issue. Try some thick felt around the cabinet edges (on the front baffle) and see if that helps.
apassgear said:
Unfortunately, I am using a cheap receiver right now. It is a push-pull A/B design though, so it should be able to handle the load. Other amps I have tried made no difference in the bass. My inductors are the heaviest I could find. I think they are 12 or 14 gage on the woofers. The caps are Solen.
SY said:
I guess it won't hurt anything to try the fourth order. Actually, I had originally intended to go that route, but was told by Madisound that they prefer to find the optimum crossover for the drivers I specified (they actually were a little unfriendly and inflexible... I guess the customer isn't always right).
I really have to go back through the loudspeaker design cookbook and read up on this again. It has been a while.
As far as diffraction goes, I don't think it is the enclosure. They have 3/4" quarter rounded edges. Then again, I'm not so sure that a 3/4" radius would be effective at the frequencies I am having problems with, and felt is cheap. I'll give it a try.
The one thing going for me (and one of the reasons I chose the drivers) is that these drivers have a fairly smooth and wide response, so they should be easy to work with. I still think the cabinet is a problem. They're ugly anyway- it's a good excuse to start over. I think I will try lowering the xover point a little. With a fourth order and MDT-33's, it shouldn't be a problem.
Thanks again for the help (Sy and apassgear)
had another thought on it...
I think I will wait until I finish my Aleph amps, and build a pair of gainclones or something that will drive the woofers well. Then I can biamp and play with the crossover points electronically. What do you think? It seems like an easier way to do the crossover. I'm a little concerned with my ability to build a fourth order that works with no acoustic measurement equipment.
I think I will wait until I finish my Aleph amps, and build a pair of gainclones or something that will drive the woofers well. Then I can biamp and play with the crossover points electronically. What do you think? It seems like an easier way to do the crossover. I'm a little concerned with my ability to build a fourth order that works with no acoustic measurement equipment.
I also plan a MTM with 2 P17WJs actively crossed with a small heil tweeter.
Amplification: Aleph (not sure if my just-finished 30 or a dual Aleph-X).
My goal is to make a TL (see the TL6 from www.theloudspeakerkit.com ), but unfortunately they don't sell plans.... and buying a australian kit is gonna kill me for forwarding expenses....
Anyway I was told it is reasonably similar to the Seas Thor, so that project will be my starting point.
Cheers
Andrea
Amplification: Aleph (not sure if my just-finished 30 or a dual Aleph-X).
My goal is to make a TL (see the TL6 from www.theloudspeakerkit.com ), but unfortunately they don't sell plans.... and buying a australian kit is gonna kill me for forwarding expenses....
Anyway I was told it is reasonably similar to the Seas Thor, so that project will be my starting point.
Cheers
Andrea
Andrea,
I was also considering going the TL route... I'm just not sure that it's a good idea with my midbass problem. I have heard that TL's can have a somewhat recessed midbass. Another option I was considering is a double chamber reflex, but the two woofers wouldn't work too well with the volumes I would have to use (the upper chamber is so small, it would be difficult getting them to fit well).
For now, the plan is to finish up a couple sets of amps and a preamp, and start experimenting with bi-amping and different filters. After that, I will be trying out some different cabinet types. Maybe I'll start with the enclosures first- MDF is cheap!
Good luck on your design.
Steve
I was also considering going the TL route... I'm just not sure that it's a good idea with my midbass problem. I have heard that TL's can have a somewhat recessed midbass. Another option I was considering is a double chamber reflex, but the two woofers wouldn't work too well with the volumes I would have to use (the upper chamber is so small, it would be difficult getting them to fit well).
For now, the plan is to finish up a couple sets of amps and a preamp, and start experimenting with bi-amping and different filters. After that, I will be trying out some different cabinet types. Maybe I'll start with the enclosures first- MDF is cheap!
Good luck on your design.
Steve
I got into this thread rather late... so I have a few things to add.
I agree with going for the 4th order L-R crossover - but again, to reitterate - an ACOUSTIC 4th order. For a general rule of thumb, in an MTM design, the best way to go is to use a 2nd order lowpass on the woofers and a 3rd order highpass on the tweeters. This allows the phasing of the drivers to match better, and will get rid of a rather nasty notch at the crossover frequency. This will undoubtedly improve midrange performance.
Also, you complain about midbass. I don't mean to sound like a jerk, but the P17 is not much of a driver in my opinion. Its a great driver for an early project, but I'd advise checking out some different ones. I'd recommend the Peerless 7" CSX driver - this blows the pants off the P17 for midbass detail and yet still maintains some very clean and smooth midrange. Not too smooth where it lacks detail (as in your standard Poly cone - i.e. the P17), but not harsh either. Good mix.
The Vifa PL14 is an unbeleivable driver. It's midbass is unreal for a 5" - better than the Peerless above. I feel it has a bit more detail than say the Focal 4211, which is also a GREAT driver. All I'm saying is consider using a different driver if you want to improve the midbass.
Baffle step compensation is really easy to do electrically - I would definetly try this before redoing your cabinet. May also want to consider how difficult it may be to alter your port tuning. If you need to lenthen the port, you can stuff the port with a bunch of straws... and pull the straws out to the desired length of the port. Pretty neet trick for tweaking the port.
Good luck -
I agree with going for the 4th order L-R crossover - but again, to reitterate - an ACOUSTIC 4th order. For a general rule of thumb, in an MTM design, the best way to go is to use a 2nd order lowpass on the woofers and a 3rd order highpass on the tweeters. This allows the phasing of the drivers to match better, and will get rid of a rather nasty notch at the crossover frequency. This will undoubtedly improve midrange performance.
Also, you complain about midbass. I don't mean to sound like a jerk, but the P17 is not much of a driver in my opinion. Its a great driver for an early project, but I'd advise checking out some different ones. I'd recommend the Peerless 7" CSX driver - this blows the pants off the P17 for midbass detail and yet still maintains some very clean and smooth midrange. Not too smooth where it lacks detail (as in your standard Poly cone - i.e. the P17), but not harsh either. Good mix.
The Vifa PL14 is an unbeleivable driver. It's midbass is unreal for a 5" - better than the Peerless above. I feel it has a bit more detail than say the Focal 4211, which is also a GREAT driver. All I'm saying is consider using a different driver if you want to improve the midbass.
Baffle step compensation is really easy to do electrically - I would definetly try this before redoing your cabinet. May also want to consider how difficult it may be to alter your port tuning. If you need to lenthen the port, you can stuff the port with a bunch of straws... and pull the straws out to the desired length of the port. Pretty neet trick for tweaking the port.
Good luck -
Tieftoener said:
Hey, thanks for the ideas!
A couple questions for you:
I understand what you mean by an acoustic 4th order response, but dosen't the driver's response dictate to some extent what filters and slopes you will use to get the 4th order response? If so, can you really say for sure that a 2nd low and a 3rd high will work, or are you giving a typical example?
As for your opinion of the P17, I would have to agree, and you're definitely not a jerk for stating your opinion. It's not the most fantastic driver available. The choice would most likely be different now. Thanks for the driver recommendations- I always like to hear what other people have found. One thing I have found is that many of the highly regarded systems use drivers with more exotic cone materials. When I look up the spec sheets on these, I see that they often have a much rougher frequency response than the poly cones like the P17. I am assuming that the trade off is complexity for more resolution. Is this the case?
I will definitely try adding some passive bafflestep compensation before I do anything else. The bass response has good extension, and is fairly controlled- much more so than I would have expected from a ported system. I just have never been happy with the balance of the system. I didn't know anything about bafflestep when I built them, but I think it may take care of most of my complaints with little work. They are definitely sensitive enough to throw some away- about 92.5 db/1W.
Thanks for the help... Any other comments / suggestions are appreciated.
Steve
Today speakes are way better than what they use to be, speaking of regular ones, as mentioned on this thread so what I'm about to say may not even applay.
Years back, when the original project from D'appolito came out I built the complete Swan system as proposed by him, including the electronic crossover for biamping (at a later day).
Not satisfied with the results I started to changed passive xover components, tested 3/4th order to different aligments, series and parallel midbass configuration and what not. In the end I trashed the project and moved to other simpler systems.
My conclusion was that the high number of pasive components on the xover really killed transients and inner details besides the regular problems of lobbing / combing that you never are able to get rid off.
Adding a baffle-step will surely change the balance and help your midbass but the bass itself may become to much for a balanced sound.
I'm not discouriging the test of the Bafflestep, this is a very easy test and you have the resistor to play around for deeper or shallower effect. Having a very narrow baffle and small enclosure I would use a 4 to 4.5 mH inductor for the test (assuming 8 Ohms speaker impedance).
Let us know your findings.
Years back, when the original project from D'appolito came out I built the complete Swan system as proposed by him, including the electronic crossover for biamping (at a later day).
Not satisfied with the results I started to changed passive xover components, tested 3/4th order to different aligments, series and parallel midbass configuration and what not. In the end I trashed the project and moved to other simpler systems.
My conclusion was that the high number of pasive components on the xover really killed transients and inner details besides the regular problems of lobbing / combing that you never are able to get rid off.
Adding a baffle-step will surely change the balance and help your midbass but the bass itself may become to much for a balanced sound.
I'm not discouriging the test of the Bafflestep, this is a very easy test and you have the resistor to play around for deeper or shallower effect. Having a very narrow baffle and small enclosure I would use a 4 to 4.5 mH inductor for the test (assuming 8 Ohms speaker impedance).
Let us know your findings.
appasgear,
I have heard that said by a few different poeple on this board (about the complexity of the crossover causing more problems than it solves). I tend to lean toward the simpler approach whenever possible too. There are a few drivers out there that are using some different cone materials AND achieving flat response. Vifa's MD series come to mind. It's strange though, that the scan speak version of the glass fiber cone speakers have rough response, and that the Vifa MD series, using the same type cone and at half the price are smooth.... I don't know what to think about that.
When using a receiver that has a semi-parametric bass control, I have found through listening that 6db of boost from about 350 Hz on down really improved the balance of the system. I think the zobel is needed. I guess we will see. Thanks for the suggested starting point.
Steve
I have heard that said by a few different poeple on this board (about the complexity of the crossover causing more problems than it solves). I tend to lean toward the simpler approach whenever possible too. There are a few drivers out there that are using some different cone materials AND achieving flat response. Vifa's MD series come to mind. It's strange though, that the scan speak version of the glass fiber cone speakers have rough response, and that the Vifa MD series, using the same type cone and at half the price are smooth.... I don't know what to think about that.
When using a receiver that has a semi-parametric bass control, I have found through listening that 6db of boost from about 350 Hz on down really improved the balance of the system. I think the zobel is needed. I guess we will see. Thanks for the suggested starting point.
Steve
nobody special:
Sorry - I wasn't very clear earlier. I like the 4th order L-R acoustic approach.
Another approach that many use and have good results with is using a 2nd order LP on the woofer and a 3rd order HP on the tweeter (for MTMs) - with regards to electrical crossover. Iin a lot of cases, this second approach can actually be used to produce a 4th order L-R acoustic response... just a matter of implementation. But as you mention - driver response does have an effect on this.
Sorry - I wasn't very clear earlier. I like the 4th order L-R acoustic approach.
Another approach that many use and have good results with is using a 2nd order LP on the woofer and a 3rd order HP on the tweeter (for MTMs) - with regards to electrical crossover. Iin a lot of cases, this second approach can actually be used to produce a 4th order L-R acoustic response... just a matter of implementation. But as you mention - driver response does have an effect on this.
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