I've done a number of hours of searching and reading. I've looked at a number of the big name designs out here that we all talk about here and on other forums, but I can't seem to find what I'm looking for.
I want to build a pair of sealed cabinet MTM's to go on a shelf for 1/2 HT and 1/2 Music listening - budget ~$1,000 plus or minus. I'd also like to build a matching center channel. Anyway, since these will be back in a corner, probably <12 inches away from back and side walls, I wanted to do an un-ported enclosure. Also not sure how to cut back on BSC, since they'll be near the back and side walls. I'm already running a 15" Bash amp driven sub, nice output down to 20Hz when listening to my Stereophile Calibration CD's.
Anyway, looking for a very nice MTM in a sealed enclosure that I can sit on a shelf against walls. The Parts Express 1.0 cubic foot (28.3 liter) enclosure would be a nice cabinet to use. I like the Eros MkII design, seems like nice drivers, Vifa PL18s and SS 9500 tweets. Anybody done these in sealed enclosures?
Zaph Audio has some nice MTM's using the Vifa XG18 / Seas 27TDFC, but it's ported too. Don't know how to change the XO and BSC to adjust for sealing the cabinet.
Anybody know of proven designs for a hi0end sealed MTM bookshelf? Thanks alot for your help gents.
Treytexag
Houston
I want to build a pair of sealed cabinet MTM's to go on a shelf for 1/2 HT and 1/2 Music listening - budget ~$1,000 plus or minus. I'd also like to build a matching center channel. Anyway, since these will be back in a corner, probably <12 inches away from back and side walls, I wanted to do an un-ported enclosure. Also not sure how to cut back on BSC, since they'll be near the back and side walls. I'm already running a 15" Bash amp driven sub, nice output down to 20Hz when listening to my Stereophile Calibration CD's.
Anyway, looking for a very nice MTM in a sealed enclosure that I can sit on a shelf against walls. The Parts Express 1.0 cubic foot (28.3 liter) enclosure would be a nice cabinet to use. I like the Eros MkII design, seems like nice drivers, Vifa PL18s and SS 9500 tweets. Anybody done these in sealed enclosures?
Zaph Audio has some nice MTM's using the Vifa XG18 / Seas 27TDFC, but it's ported too. Don't know how to change the XO and BSC to adjust for sealing the cabinet.
Anybody know of proven designs for a hi0end sealed MTM bookshelf? Thanks alot for your help gents.
Treytexag
Houston
You might email Danny Ritchie at GR-Research. Has has speaker plans and kits that are not currently listed on his web site.
http://gr-research.com/index.asp
http://gr-research.com/index.asp
Great responses gents. Thanks. A couple of follow up questions.
On Jay's website for the Usher MTM he makes the following comment:
"In fact, an MTM design can easily be created if a corresponding TM design is already built and tested. Only thing that needs to be considered is a little different baffle step loss and diffraction."
Is this a true statement universally men, or was Jay only talking about this design? In other words, can I take any existing TM design and get help on the BSC and diffraction for a good speaker?
Other question, how does the Usher Usher 8945P compare to the Vifa PL18, and how does the Peerless 810921 HDS tweeter compare to the Scanspeak 9500?
Thanks allot guys, appreciate the help. If anyone has any other suggestions on a sealed high end MTM bookshelf, please do share.
Thanks,
Trey
On Jay's website for the Usher MTM he makes the following comment:
"In fact, an MTM design can easily be created if a corresponding TM design is already built and tested. Only thing that needs to be considered is a little different baffle step loss and diffraction."
Is this a true statement universally men, or was Jay only talking about this design? In other words, can I take any existing TM design and get help on the BSC and diffraction for a good speaker?
Other question, how does the Usher Usher 8945P compare to the Vifa PL18, and how does the Peerless 810921 HDS tweeter compare to the Scanspeak 9500?
Thanks allot guys, appreciate the help. If anyone has any other suggestions on a sealed high end MTM bookshelf, please do share.
Thanks,
Trey
The Vifa PL and SS 9500 are excellent drivers but a bit old designs by today's standard. Particularly the Usher 8945P has much lower distortions than the Vifa PL thanks to its advanced motor. And according to Mark K and Zaph's tests, the 810921 has lower distortions than the SS 9500 below 2 kHz, which is important for an MTM application.
I can provide a reduced BSC crossover for my Usher 8945P and Peerless 810921 MTM design. Send me an email if you're interested.
BTW, does your receiver have an auto EQ function like Audyssey?
I can provide a reduced BSC crossover for my Usher 8945P and Peerless 810921 MTM design. Send me an email if you're interested.
BTW, does your receiver have an auto EQ function like Audyssey?
Trey,
If you have a limited budget, I can also provide an MTM version of my Dayton RS180/Seas 27TDFC 2-way design. This crossover can be modified to have reduced BSC.
BTW, if you have an auto EQ like Audyssey, fine-tuning or voicing of a speaker is a moot point. So, subtle FR differences between TM and MTM designs are no longer meaningful in this case. The method I use for crossover simulation is more than adequate to provide a sufficiently good result. So, you may want to focus on drive units' quality for your MTM. As for the quality of drivers used, you will be hard pressed to find a better MTM design than my Usher/Peerless design.
If you have a limited budget, I can also provide an MTM version of my Dayton RS180/Seas 27TDFC 2-way design. This crossover can be modified to have reduced BSC.
BTW, if you have an auto EQ like Audyssey, fine-tuning or voicing of a speaker is a moot point. So, subtle FR differences between TM and MTM designs are no longer meaningful in this case. The method I use for crossover simulation is more than adequate to provide a sufficiently good result. So, you may want to focus on drive units' quality for your MTM. As for the quality of drivers used, you will be hard pressed to find a better MTM design than my Usher/Peerless design.
Jay, thanks so much for responding, you too kind. I really want to go the other way, larger budget. Looking for a sealed MTM using very nice drivers, perhaps like Seas Excel and Seas Milenium tweets - perhaps. I only mention the Seas because I've heard those and they sound excellent, in an TL design anyway. I'm looking for a proven design that folks have built and tweaked. What are your thoughts?
BTW men, thanks again for all the great posts here. I've lost serious sleep reading here and not sleeping!!
Treytexag
BTW men, thanks again for all the great posts here. I've lost serious sleep reading here and not sleeping!!
Treytexag
treytexag said:
Okay if this is the case, as I said above, subtle voicing elements such as pinpoint-accurate BSC and tweeter padding in so-called "proven" designs are a moot point since your Audyssey can handle them.
I believe my Usher 8945P/Peerless 810921 in a sealed PE 1 cu ft cabinet with a reduced BSC crossover is what you're looking for. How can I say so? Take a look at Zaph's driver test pages:
http://www.zaphaudio.com/6.5test/compare.html (for 6.5" midwoofer tests)
http://www.zaphaudio.com/tweetermishmash/compare.html (for tweeter tests)
I'm not sure you can read these measurement charts. What you need to see in these pages is various 6.5" midbass drivers' and tweeters' harmonic distortion measurements, because harmonic distortions in the drivers' operating ranges are motor-induced property that cannot be corrected by crossovers or EQ no matter how well the crossovers are designed. Click the "Harmonic distortion" tab. You'll see each tested driver's harmonic distortion sweep over a frequency range. What you want to see in these graphs is the levels of the 3rd order (blue line) and 5th order (grey line) harmonics since they are generally considered to be acoustically obtrusive.
For 6.5" drivers, compare these levels across drivers in a frequency range from 100 Hz to 2 kHz to see how low the levels are. Compare the Usher 8945P's distortion levels to other drivers'. You can easily compare any two drivers by toggling between them. You'll see that the 8945P is one of the best performers regardless of price. Only the Scan Speak 18W8531G can rival the 8945P---overall, the 8945P's distortion levels are slightly lower. It is better than Seas Excel, Seas Prestige, Peerless, and Dayton. For example, compare the 8945P and the Seas CA18RLY (a bigger brother of the CA15RLY used in many existing designs). You'll see the 8945P's distortion levels are significantly lower than the CA18RLY.
The same thing applies to the Peerless 810921 HDS tweeter. For tweeters, compare their distortion levels in a frequency range from 1 kHz to 4 kHz because this range determines a tweeter's real-world performance. You'll see that only tweeters that measure (ever slightly) better than the 810921 are the Scan Speak 6600, 7100, and 7000. But I don't think this small difference is much audible. Note that there are no Seas Excel tweeters that outperform the Peerless 810921. Even the Seas Prestige line 27TBFC/G and 27TDFC measure better than the Seas Millennium.
In sum, I don't think you'll be able to find any existing DIY MTM designs---even if they luckily meet your exact requirements: can be used in a sealed 1 cu ft cabinet and with reduced BSC crossover---that have lower system harmonic distortions than this 8945P/810921 MTM design. With respect to drive units' quality, this design is top-notch regardless of price. This is the reason why I described my 8945P/810921 2-way as "truly high-end" in my web page. And I'm proud of what my crossover design does for this driver combination.
-jAy
Hi,
this is a design, that could be just the right! ;-)
This design is intended to be placed close to a wall. It shows high efficiency (93dB@2.83Vq1m) and allows for high dynamics.
It can play in small rooms (>12m²) and allows for small listening distances. In large rooms (>30m²) and freely standing it should be supported by a large sub below ~60Hz. It uses a pair of the Vifa 17WN225-8 in 12.5L BR each. As CB it would show a Qtb of 0.7, so it should be no prob to build it as a CB with similar dimensions (H60*W24*D30cm). Though it is a quite not a stylish new driver this is one of the very best 17cm drivers you could use. Equally linear response, smooth rolloff, low distortion and good efficincy are nearly impossible to find in this size class, especially not with an similar price tag attached to it.
The Tweeter is a horn loaded XT25. Besides increasing efficiency and reducing distortion the horn offsets the driver ´backwards´ which leads to an excellent step response. Directivity is high of course, but on the other hand this decreases the part of early reflections which is useful for a bookshelf box.
The crossover needed is simple and doesn´t need tons of parts as other designs
Unluckily I lost some of my measurements but here are some of the left ones.
Distortion level at 96dbSPL@1m:
At this high level of SPL distortion is very well arranging around0.3%. One can clearly see that the tweeter distortion consists of nearly only K2.
Impedance
It is a 4Ohm speaker, with low phase shift. Combined with the high efficiency this is very easy to drive even with Tube amps.
I drive it with a KR340 (SE-Triode with ~20W) which is a combination made in heaven
Step response
The ´time aligned design´ and lack of resonances in freq-response clearly show in this excellent step reponse.
midwoofer freq responses wo crossover
and here the same with crossover
The tweeter wo crossover
Crossing over takes place around 2-3kHz. The tweeter features a higher crossover frequency (electrically than acoustically), thereby ´equalizing´ the raising amplitude response. Besides getting a linear amplitude response this reduces power stress on the tweeter, reduces distortion, increases the dynamic range and sounds smooth but more lively than the pure tweeter. Too you don´t need any resistances to get the efficiency down to woofer level...less parts count..better sound
jauu
Calvin
this is a design, that could be just the right! ;-)
An externally hosted image should be here but it was not working when we last tested it.
This design is intended to be placed close to a wall. It shows high efficiency (93dB@2.83Vq1m) and allows for high dynamics.
It can play in small rooms (>12m²) and allows for small listening distances. In large rooms (>30m²) and freely standing it should be supported by a large sub below ~60Hz. It uses a pair of the Vifa 17WN225-8 in 12.5L BR each. As CB it would show a Qtb of 0.7, so it should be no prob to build it as a CB with similar dimensions (H60*W24*D30cm). Though it is a quite not a stylish new driver this is one of the very best 17cm drivers you could use. Equally linear response, smooth rolloff, low distortion and good efficincy are nearly impossible to find in this size class, especially not with an similar price tag attached to it.
The Tweeter is a horn loaded XT25. Besides increasing efficiency and reducing distortion the horn offsets the driver ´backwards´ which leads to an excellent step response. Directivity is high of course, but on the other hand this decreases the part of early reflections which is useful for a bookshelf box.
The crossover needed is simple and doesn´t need tons of parts as other designs
Unluckily I lost some of my measurements but here are some of the left ones.
Distortion level at 96dbSPL@1m:
An externally hosted image should be here but it was not working when we last tested it.
At this high level of SPL distortion is very well arranging around0.3%. One can clearly see that the tweeter distortion consists of nearly only K2.
Impedance
An externally hosted image should be here but it was not working when we last tested it.
It is a 4Ohm speaker, with low phase shift. Combined with the high efficiency this is very easy to drive even with Tube amps.
I drive it with a KR340 (SE-Triode with ~20W) which is a combination made in heaven
Step response
An externally hosted image should be here but it was not working when we last tested it.
The ´time aligned design´ and lack of resonances in freq-response clearly show in this excellent step reponse.
midwoofer freq responses wo crossover
An externally hosted image should be here but it was not working when we last tested it.
and here the same with crossover
An externally hosted image should be here but it was not working when we last tested it.
The tweeter wo crossover
An externally hosted image should be here but it was not working when we last tested it.
Crossing over takes place around 2-3kHz. The tweeter features a higher crossover frequency (electrically than acoustically), thereby ´equalizing´ the raising amplitude response. Besides getting a linear amplitude response this reduces power stress on the tweeter, reduces distortion, increases the dynamic range and sounds smooth but more lively than the pure tweeter. Too you don´t need any resistances to get the efficiency down to woofer level...less parts count..better sound
jauu
Calvin
AJinFLA said:
I wouldn't need to ask this design too much of a vertical off axis dispersion. We can more or less predict it based on the info he gave. According to measurements, the crossover must be acoustic LR2 with tweeter polarity inverted. Its vertical center lobe should be much narrower than a LR4 design with a lower xover point. Not much of a sweet spot vertically, but I wouldn't mind it if that fits the design goal---listening at tweeter axis when placed vertically. Not suitable for horizontal use for CC.
MisterTwister said:
I didn't mean to predict the tweeter's off-axis high frequency rolloff. I meant the crossover's vertical polar response around the crossover frequency. Oh, I forgot to say about the midwoofers' lobing errors. With 2.5 kHz LR2, the 6.5" midwoofers in MTM are more prone to comb filtering when the listening height is off axis vertically. But again, if this fits the design goal, I wouldn't mind. This must not have been designed for horizontal use as CC whereas my MTM design with 1.6 kHz LR4 can be used as a hortizontal CC.
Hi,
I don´t have vertical response curves any more, but the sweet spot is small, vertically as well as horizontally. The horn has a rather high directivity. So its best to sit right on the tweeter´s axis.
But I found this one. Its the pure tweeter with horn measured from 0°-45° in 5° steps.
The crossover for the bass consists of a series inductor and a RC parallel network for impedance correction.
The tweeter features a LC-network (12dB) and a parallel notch on its Fs. There´s a RCL-notch at the input connectors of the crossover to linearize impedance (with one of my computer crashes the crossover files have vanisched too
) so I don´t know the exakt values at the moment, but could look them up if there´s deeper interest.
The horn is made from aluminium.
I measured the shape of the tweeters frontplatte, calculated the shape using the tractrix-formula and went to a shop, payed some bucks a few days later and it fitted perfectly and works well ;-)
So its rather a matter of the capabilities of a professional shop. I wouldn´t recommend to do it yourself unless You have the right machines and knowledge to do so. At the back face of the horn there is kind of small ´blade´ of ~42mm diameter. This blade fits the shape of the tweeter´s frontplate very precisely. It centers the horn on the tweeter and the transition from membrane into the hornm is very smooth.
The tweeter is simply screwed to the horn and the horn is glued with silicone into the box front from inside.
jauu
Calvin
I don´t have vertical response curves any more, but the sweet spot is small, vertically as well as horizontally. The horn has a rather high directivity. So its best to sit right on the tweeter´s axis.
But I found this one. Its the pure tweeter with horn measured from 0°-45° in 5° steps.
An externally hosted image should be here but it was not working when we last tested it.
The crossover for the bass consists of a series inductor and a RC parallel network for impedance correction.
The tweeter features a LC-network (12dB) and a parallel notch on its Fs. There´s a RCL-notch at the input connectors of the crossover to linearize impedance (with one of my computer crashes the crossover files have vanisched too
) so I don´t know the exakt values at the moment, but could look them up if there´s deeper interest.The horn is made from aluminium.
I measured the shape of the tweeters frontplatte, calculated the shape using the tractrix-formula and went to a shop, payed some bucks a few days later and it fitted perfectly and works well ;-)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
So its rather a matter of the capabilities of a professional shop. I wouldn´t recommend to do it yourself unless You have the right machines and knowledge to do so. At the back face of the horn there is kind of small ´blade´ of ~42mm diameter. This blade fits the shape of the tweeter´s frontplate very precisely. It centers the horn on the tweeter and the transition from membrane into the hornm is very smooth.
An externally hosted image should be here but it was not working when we last tested it.
The tweeter is simply screwed to the horn and the horn is glued with silicone into the box front from inside.
jauu
Calvin
Calvin said:
The horn loaded tweeter's high frequency rolloff shouldn't be much of an issue. In general, a wave guided tweeter has a better HF off-axis response within a certain degree of listening window.
A more important off-axis characteristic of your design should be its vertical lobing patterns around the crossover frequency. Generally, acoustic LR2 crossovers have narrower center lobes over a wider frequency range than LR4 crossovers. Also, higher crossover frequency and shallow LP rolloff required by LR2 crossovers make this MTM design more prone to the midwoofers' lobing errors. But I wouldn't necessarily see this vertically narrow sweet spot as a weakness. Unless it is used as a horizontal center channel speaker, this type of design gives its unique power response which may be preferred by some people.
Hi,
the initial point to use a horn simply was, that the two 17WN225 are slightly more efficient than the XT25. So I needed a device that would raise the efficiency somehow, or I´d used a lossy LP-filter for the woofers. Since it was intended to use the box with amps as low as 10W in wattage, I decided to save on efficiency and use the horn. As I was not very familiar with wave guides and only found some with quite large outer diameter I opted for the easier and smaller Traktrix-horn. Maybe I was just lucky but the resultant freq-response allowed for a simple crossover design with a (electrically) raised crossover-freq that has several advantages I ´ve mentioned before. Experiments with steeper filter curves (towards LR4) and lower CO-freq always gave inferior sonic results (to my taste), though in some cases directivity was broader. But anybody who wants to build this box can try his own.
Here´s a pic of the CO:
Since the tweeter loads the horn just up to 15kHz the efficiency above 15kHz equals the pure tweeters efficiency. This means that the box´s freq-response drops above 15kHz slightly. Since there is nearly no music signal to be reproduced here any more I prefer a slightly tilted response in this freq-range, because I often like to listen at loud levels and such a freq-response is much more listenable to at very high levels of SPL. The box played at the Munich fair in 2004 (sidenote: one reporter of a German HiFi-magazine told me that he liked the box very much, because it was one of very few that could reproduce ´handclapping´ realistically) and on several DIY workshops. Just few listeners noticed the drop as long as they sat on-axis. But a lot of listeners were atonished to hear the XT25 sound so dynamic and lively on one hand and silky smooth on the other hand. Especially owners of high wattage amps low efficiency speakers were astonished about the dynamic range that a 20W SE-tubeamp playing through the box allowed for.
Anyway, the design goals for this speaker were:
- small rooms down to 10m²
- larger rooms >30m² with the support of a sub
- placing close to the wall (there is not much place in small rooms )
- short listening distances (see abobe)
- compactness (see above)
- high efficiency -->SE-Tube amp as drive
Especially the first goal asked for a rather narrow directivity. This lead to the choice of the XT25 and the rather ´big´ 17WN225.
Goals no. 2 and 6 lead to the use of a second 17WN225 and the BR loading.
Goals no. 3 and 5 lead to a design with a elevated Fb of ~55Hz-60Hz. Placed close to the wall the lower freqs are ´amplified´ and the box reaches down linearly to ~40Hz. Bass sounds precise and clean, while most other boxes with lower Fb and intended to be positioned free standing sound boomy.
Goal no4 lead to the symmetric MTM-design.
In larger rooms and in a free stading position the box reaches linearly down to ~60Hz. This makes the integration of a subwoofer very easy, especially so when the satellites are not to be filtered (fullrange) and the sub is just run in parallel.
This is a pic of a setup in a studio of ~45m² floor space.
The Calvini driven by a KR Antares320 (SE-Tube 22W) supported by a dipole sub driven with BMS power amps and Pre.
jauu
Calvin
ps. Oh before I forget...... even with a nice and well manufactured cabinet and first class crossover parts You can stay well below the 1.000$ budgetary limit
the initial point to use a horn simply was, that the two 17WN225 are slightly more efficient than the XT25. So I needed a device that would raise the efficiency somehow, or I´d used a lossy LP-filter for the woofers. Since it was intended to use the box with amps as low as 10W in wattage, I decided to save on efficiency and use the horn. As I was not very familiar with wave guides and only found some with quite large outer diameter I opted for the easier and smaller Traktrix-horn. Maybe I was just lucky but the resultant freq-response allowed for a simple crossover design with a (electrically) raised crossover-freq that has several advantages I ´ve mentioned before. Experiments with steeper filter curves (towards LR4) and lower CO-freq always gave inferior sonic results (to my taste), though in some cases directivity was broader. But anybody who wants to build this box can try his own.
Here´s a pic of the CO:
An externally hosted image should be here but it was not working when we last tested it.
Since the tweeter loads the horn just up to 15kHz the efficiency above 15kHz equals the pure tweeters efficiency. This means that the box´s freq-response drops above 15kHz slightly. Since there is nearly no music signal to be reproduced here any more I prefer a slightly tilted response in this freq-range, because I often like to listen at loud levels and such a freq-response is much more listenable to at very high levels of SPL. The box played at the Munich fair in 2004 (sidenote: one reporter of a German HiFi-magazine told me that he liked the box very much, because it was one of very few that could reproduce ´handclapping´ realistically) and on several DIY workshops. Just few listeners noticed the drop as long as they sat on-axis. But a lot of listeners were atonished to hear the XT25 sound so dynamic and lively on one hand and silky smooth on the other hand. Especially owners of high wattage amps low efficiency speakers were astonished about the dynamic range that a 20W SE-tubeamp playing through the box allowed for.
Anyway, the design goals for this speaker were:
- small rooms down to 10m²
- larger rooms >30m² with the support of a sub
- placing close to the wall (there is not much place in small rooms
)- short listening distances (see abobe)
- compactness (see above)
- high efficiency -->SE-Tube amp as drive
Especially the first goal asked for a rather narrow directivity. This lead to the choice of the XT25 and the rather ´big´ 17WN225.
Goals no. 2 and 6 lead to the use of a second 17WN225 and the BR loading.
Goals no. 3 and 5 lead to a design with a elevated Fb of ~55Hz-60Hz. Placed close to the wall the lower freqs are ´amplified´ and the box reaches down linearly to ~40Hz. Bass sounds precise and clean, while most other boxes with lower Fb and intended to be positioned free standing sound boomy.
Goal no4 lead to the symmetric MTM-design.
In larger rooms and in a free stading position the box reaches linearly down to ~60Hz. This makes the integration of a subwoofer very easy, especially so when the satellites are not to be filtered (fullrange) and the sub is just run in parallel.
This is a pic of a setup in a studio of ~45m² floor space.
An externally hosted image should be here but it was not working when we last tested it.
The Calvini driven by a KR Antares320 (SE-Tube 22W) supported by a dipole sub driven with BMS power amps and Pre.
jauu
Calvin
ps. Oh before I forget...... even with a nice and well manufactured cabinet and first class crossover parts You can stay well below the 1.000$ budgetary limit
Hi,
TBH I think Calvins design should go in a different thread.
I do not think it is "just right" .....
It is very suitable in some respects for this particular application,
but not in all respects IMO. It is not suitable as a center or IMO
afguably for HT L+R either due to dispersion / sweet spot issues.
Why do people always want to spend a notional budget and get
the "best / most expensive" drivers they can within that budget ?
The base level is $120 or $150 per enclosure, which is on grief
avoidance well worth it unless your a woodworking genius.
However they are not the last word on high performance cabinets,
(but very good for a basic MDF box, especially the curved version),
you can start another debate elsewhere on how to improve them
and at what point / with what drivers / loudspeaker design do
they become a limiting factor (also if they actually do ........).
You can ignore Jay_WJ at your peril, and pointlessly spend more
on something less satisfactory with more expensive / flashy drivers.
http://www.seas.no/index.php?option=com_content&task=view&id=24&Itemid=42
Is flashy / expensive for what you get but is not an optimised center.
The enduring popularity of MTM's for centers is not beyond me, but
they are fundamentally unsuitable for the job, but given that Zaphs
and Jay_WJs designs do minimise the problems of this application.
FWIW the Eros MK II does appear to be suitable (low crossover
frequency) and should work well in 1 cuft sealed enclosures for
your intended application.
However the driver choice is not based on extensive distortion
testing, more on word of mouth that the PL18 is very good, e.g.
see http://www.humblehomemadehifi.com/Tempo.html .
However TG has lifted this directly from the Eros write up .....
The tweeter meanwhile is expensive and therefore must be good ....
Zaphs tests indicate the 810921 is a lot better bet than the
9500 for crossing over as low as possible, this is wanted here.
They also indicate the best bass/mid drivers are like that because
of the way they are built, AFAIK the PL18 does not have any of
the advanced features of the 8945P, and is likely similar to the
more prosaic Seas paper drivers.
Anything in common with the Scanspeak 18W8545K as claimed
by the "reputation" ? (The PL18 is a 18W8545K on the cheap),
technically no. In fact what is claimed in this "reputation" is
more accurately true of the Usher 8945P.
/sreten.
edit : just add IMO you'd be better off with 8945P/810921 MT's.
TBH I think Calvins design should go in a different thread.
I do not think it is "just right" .....
It is very suitable in some respects for this particular application,
but not in all respects IMO. It is not suitable as a center or IMO
afguably for HT L+R either due to dispersion / sweet spot issues.
Why do people always want to spend a notional budget and get
the "best / most expensive" drivers they can within that budget ?
The base level is $120 or $150 per enclosure, which is on grief
avoidance well worth it unless your a woodworking genius.
However they are not the last word on high performance cabinets,
(but very good for a basic MDF box, especially the curved version),
you can start another debate elsewhere on how to improve them
and at what point / with what drivers / loudspeaker design do
they become a limiting factor (also if they actually do ........).
You can ignore Jay_WJ at your peril, and pointlessly spend more
on something less satisfactory with more expensive / flashy drivers.
http://www.seas.no/index.php?option=com_content&task=view&id=24&Itemid=42
Is flashy / expensive for what you get but is not an optimised center.
The enduring popularity of MTM's for centers is not beyond me, but
they are fundamentally unsuitable for the job, but given that Zaphs
and Jay_WJs designs do minimise the problems of this application.
FWIW the Eros MK II does appear to be suitable (low crossover
frequency) and should work well in 1 cuft sealed enclosures for
your intended application.
However the driver choice is not based on extensive distortion
testing, more on word of mouth that the PL18 is very good, e.g.
see http://www.humblehomemadehifi.com/Tempo.html .
However TG has lifted this directly from the Eros write up .....
The tweeter meanwhile is expensive and therefore must be good ....
Zaphs tests indicate the 810921 is a lot better bet than the
9500 for crossing over as low as possible, this is wanted here.
They also indicate the best bass/mid drivers are like that because
of the way they are built, AFAIK the PL18 does not have any of
the advanced features of the 8945P, and is likely similar to the
more prosaic Seas paper drivers.
Anything in common with the Scanspeak 18W8545K as claimed
by the "reputation" ? (The PL18 is a 18W8545K on the cheap),
technically no. In fact what is claimed in this "reputation" is
more accurately true of the Usher 8945P.
/sreten.edit : just add IMO you'd be better off with 8945P/810921 MT's.
at HTGuide, there are a couple of options with no/reduced baffle step using the Dayton RS drivers.
The designers have top notch reputations, the design process is extensively documented and there are many people on the site who have built the projects. Many of these have centres too.
http://www.htguide.com/forum/forumdisplay.php4?f=39.
The drivers in Jay's project sure are tempting. Have you looked at Zaph's reviews or these? How exciting is it to have a tweeter that competes with the best for a measly $80? I love the looks of that Usher driver too. If we didn't have a baby on the way I'd be all over these.
Well, have fun.
David
The designers have top notch reputations, the design process is extensively documented and there are many people on the site who have built the projects. Many of these have centres too.
http://www.htguide.com/forum/forumdisplay.php4?f=39.
The drivers in Jay's project sure are tempting. Have you looked at Zaph's reviews or these? How exciting is it to have a tweeter that competes with the best for a measly $80? I love the looks of that Usher driver too. If we didn't have a baby on the way I'd be all over these.
Well, have fun.
David
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