@454Casull One of the few excellent, reasonably priced 19mm domes are the Seas 22TAF/G. I'd cross that one around 3k being it has a larger emissive surface for a 19mm.dome with its large surround. Its a great tweeter suitable for use with a 2" mid dome.
Looking forward to this!
Will need to check this out. Been getting really into synth pop adjacent music lately. Prefab Sprout and Talk Talk have been my go tos for the past month.
Since it's a d&d 8c clone, the rs225 will be acting more as a midbass, but he doesn't listen very loudly. AnywaysI, thanks for your reply. I feel like I always learn something when we chat. This whole thread has been very educational for me
Right. The Vifa units do have a leg up as they are compact and allow for very tight spacing with a mid.
This was actually the start of my journey 15 years ago - the Seas with Dayton 2" dome.
All these points are easy to measure - with THD. And you can add some other measurement signals but unlinearities are not hard to capture.
I'm not going the "good enough" route in a design - the crossover point is not allowed to bring extra THD! Have a look, that's from the 2x12"/3"/1" at 108dBSpl. The Hypex module is already in protection mode for the tweeter above a few kHz (strict settings for this project) but at the crossover frequency there is not the slightest sign of additional distortions. I mean T25 tweeters burn down before they reach 1% THD in the 2-5kHz area ... these are WAY more clean as older designs. The 3" shows more THD in that area ...
But they won't do 105dBSpl at the listening position - that for sure. A 1" is not capable of that, esp. when crossed at 2kHz. Maybe at >3,5kHz cause music content goes down at higher frequencies but for these levels I would stay away from 1" at all. T34 or compression driver.
And 105dBSpl ... that's BRUTAL. I mixed my live shows with lower SPL. That's movie peak level - but with way higher compressed material and long duration.
People - get your (good) phone SPL app and have a measurement how loud you hear when cranking up. Then you have a design goal.
p.s.: Be careful with T25 tweeters when you play really loud. These die before you hear high distortions. Certified during my measurements 🤓
The analog signal path is simply gone for most of us. I record digitally. May main music sources are digital. While I also have LPs it's more a fun thing as serious listening.
So I pushed the last D/A conversion as far down the chain as possible - directly before the power amp. You need a very high dynamic range setup for that to work without noise and artefacts but nowadays it's easy to achieve.
You should tip your toe deeper in DSP crossovers ;-)
This was the reason why I went from D'Appolito to one bigger midrange. Why I really like Coax speakers. Why I use small driver distances and 2 hard domes for midrange and tweeter. Why I don't use brick wall filters. Cause I really dislike that effect.
Classic is a 6" paper cone and metal tweeter with no waveguide... part of that effect is the uneven off axis performance btw 😉
I remember one prototype I built - 12" PA woofer, 6" midrange and 1" compression driver. Really good sound with lot's of details on axis (this was in times where 12"/2" was the standard) - but it didn't "integrate". The sound of the 6" and 1" didn't fit and off axis performance was uneven, it sounded different all over the room with too much mid energy. While it was better as a 12" midrange it was not good enough.
Distance of 1" and 3" is about 80mm when optimised. With correct delay and fitting acoustic slopes it's really close to a coax, you get a super stable image between them. It's a 3" to 1" metal dome and both have wide off axis performance cause of the low crossover.
I worked for a long time on that concept to get it right and only the appearance of small Beryllium tweeters made that click - you would need very special ears to hear the transition between these 2.
But of course there ARE many speakers and concepts which don't appear as point source and have different tonality at different frequency ranges.
Getting back to the domes, how high can you cross Bliesma m142P?
I can buy these domes trough friend with a good discount (OEM), but to quote hificompass: "Based on these measurements, I would recommend using the M142P-6 as the midrange of the highest quality loudspeakers in the 200Hz to 2kHz frequency range. "
There is break-up at 3-4k, so is this dome "passable" at all with dome tweeter when wanting to use 3k crosspoint?
Or maybe wavequide and big tweeter like T34-S or T35C002 at 2k?
I can buy these domes trough friend with a good discount (OEM), but to quote hificompass: "Based on these measurements, I would recommend using the M142P-6 as the midrange of the highest quality loudspeakers in the 200Hz to 2kHz frequency range. "
There is break-up at 3-4k, so is this dome "passable" at all with dome tweeter when wanting to use 3k crosspoint?
Or maybe wavequide and big tweeter like T34-S or T35C002 at 2k?
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@matsurus I would wonder about 250 Hz at the bottom to one of their T34 series tweeters a bit lower than 2 Khz, perhaps with series notch filters to address the 3k and 7 k peaks which may be causing the 3rd and 5th harmonic distortion products lower down in the intended passband? But curious about other replies, as I suspect @profiguy might disagree and @IamJF might agree 🙂.
But I might also ask if my friend could help me get the M142S or A instead 🙂.
I am having a hard time resisting the 142A to pair with T34Bs in a 3-way v going with a 2-way, but definitely on the countdown to pull the trigger before the 90-day pause expires...as my father would say, "time to crap or get off the pot" (hope that translates!)
Bill
But I might also ask if my friend could help me get the M142S or A instead 🙂.
I am having a hard time resisting the 142A to pair with T34Bs in a 3-way v going with a 2-way, but definitely on the countdown to pull the trigger before the 90-day pause expires...as my father would say, "time to crap or get off the pot" (hope that translates!)
Bill
@matsurus I have little experience with the M142P, only a few test sweeps and an uncalibrated HD measurement, which isn't that relevant due to lack of comparative reference. I can however say the engineering that went into this driver was of highest caliber. Its rare to see an odd combination of paper membrane with a motor of this magnitude.
Anyways, based on the brief experience, you would want to cross under 1.4k very steep. Its not a driver I'd deem suitable for common design, but more of a highly specialized application. A very good 16cm cone driver would be more suitable for this purpose IMO. The limitations of this compared to the big M142P would be thermal power handling, but a decent large VC equipped 6" driver would be more than adequate, plus it would be able to cross higher ie. SB 6MW150D. I've used these in several applications with excellent success. I've specifically chosen the T35C002 for use in the TW034 WG crossed about 2k 3rd order for studio monitor applications (this is where a lower than 3k cross would be appropriate). The other option is the newer Satori TW29TXNWG or Seas T29X001 in a WG would be a good fit. I suspect there are close similarities to the equally sized textreme dome models due to only one major supplier of the raw diaphragms, which get trimmed to fit specific drivers.
My other preference for a good combination would be the M74T with a T34B. The M74A is an option but it requires considerable care to deal with the severe 10k spike. I'd prefer a staggered pair of M74A shaded to a T34A or B. I dont know if thats a satisfactory answer to your concerns here, but these are examples for what I'd consider low compromise top notch driver combinations.
I can try looking up my references with the T35C002, which was adapted to the Troels TW034 WG. The surround is very narrow on the T35C002 which helps improve in-WG performance. This big Seas dome is quite remarkable how high up in range it can play along with how low it goes without the usual complaints.
Anyways, based on the brief experience, you would want to cross under 1.4k very steep. Its not a driver I'd deem suitable for common design, but more of a highly specialized application. A very good 16cm cone driver would be more suitable for this purpose IMO. The limitations of this compared to the big M142P would be thermal power handling, but a decent large VC equipped 6" driver would be more than adequate, plus it would be able to cross higher ie. SB 6MW150D. I've used these in several applications with excellent success. I've specifically chosen the T35C002 for use in the TW034 WG crossed about 2k 3rd order for studio monitor applications (this is where a lower than 3k cross would be appropriate). The other option is the newer Satori TW29TXNWG or Seas T29X001 in a WG would be a good fit. I suspect there are close similarities to the equally sized textreme dome models due to only one major supplier of the raw diaphragms, which get trimmed to fit specific drivers.
My other preference for a good combination would be the M74T with a T34B. The M74A is an option but it requires considerable care to deal with the severe 10k spike. I'd prefer a staggered pair of M74A shaded to a T34A or B. I dont know if thats a satisfactory answer to your concerns here, but these are examples for what I'd consider low compromise top notch driver combinations.
I can try looking up my references with the T35C002, which was adapted to the Troels TW034 WG. The surround is very narrow on the T35C002 which helps improve in-WG performance. This big Seas dome is quite remarkable how high up in range it can play along with how low it goes without the usual complaints.
@Bill Brown I'd only consider the M142A if you want to entertain a T34A or B crossed that low. I wouldn't do that myself though. The M74A with the T34A is more than capable with a 2nd order 500 hz mid HP. As long as you notch 10k it will be excellent, considering how close CTC is. You can always play with the MF/HF transition.
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Is that the only version you can get at OEM price? I'm not an expert on dome mids but that paper dome mid is not the one I would buy. The breakup is in what should be the usable passband. I don't see the purpose of a dome mid with that limitation, that compromise. Personally , with my budget it would have to be the silk dome or the Alum/Mag dome. But right now I am VERY happy with the Scanspeak dome. Its made the midrange come alive compared to my two way speakers.
Thank you, @profiguy. Yes that is the question-
M142A + T34B crossed lowish v
T34B + (? 8") midwoofer v
T34B + M74A + woofer
I am intrigued and have been thinking about your long writeup from yesterday. One aspect I continue to think about is what you describe as the most sensitive range or critical midrange of 500Hz-4Khz and avoiding crossovers there. Years ago I read an author who described the "telephone band" of perhaps 300Hz-6khz and similarly wished to avoid crossovers in that range (quite difficult, of course). You like 500Hz as the lower number or is that largely based on the capabilities of the mid-domes?
I guess the fundamental question is where are the best (or least damaging) crossover points in a situation like this (with the drivers under consideration):
~500Hz and ~3.5kHz or
~1.3kHz
Bill
M142A + T34B crossed lowish v
T34B + (? 8") midwoofer v
T34B + M74A + woofer
I am intrigued and have been thinking about your long writeup from yesterday. One aspect I continue to think about is what you describe as the most sensitive range or critical midrange of 500Hz-4Khz and avoiding crossovers there. Years ago I read an author who described the "telephone band" of perhaps 300Hz-6khz and similarly wished to avoid crossovers in that range (quite difficult, of course). You like 500Hz as the lower number or is that largely based on the capabilities of the mid-domes?
I guess the fundamental question is where are the best (or least damaging) crossover points in a situation like this (with the drivers under consideration):
~500Hz and ~3.5kHz or
~1.3kHz
Bill
No, i can buy the whole range with discount..
Textreme 142 could be other choise, i have to read about it..
Probably will end up with m74 silk or textreme, but one can dream!
Ya, that paper dome doesn't have the wide bandwidth of metal, or the breakup suppression of silk. Cant see any advantage for it at all. Maybe I'm missing something? Textreme is all the rage now, but too expensive for me to experiment with. I should add, its not that I am against paper, I have some SB Satori paper 6.5's that are very clean from 30hz to 2500Hz.
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@Bill Brown When you consider the transition point of omni to directional for our hearing is about 300 hz, that's where the critical midrange starts. The upper limit on the sensitive range is 5k, where the Pina stops adding resonant gain. Above 5k we hear Iittle harmonic content, which is limited to just another octave above that when the audible band stops. So yes, 300 - 5k is about the touchy range that needs to be homogenous.
The starting range practical for good dynamic range and power handling on a 75mm mid dome is about 500 hz 2nd order. You'd then run it out to its upper limit which allows for a smooth transition to a smaller HF dome. I'd choose 3.5k due to the off axis dip being in the most advantageous place, which allows for a natural sounding transition to the tweeter. You can choose a lower point for this, but I'd stick to 3.5k. Its also a natural pivot point for crossover EQing and implementing an adjustable HF pad. There are big advantages to using one of these in reflective rooms and treble heavy source material. A shelf EQ pivoting around this for the HF allows for versatile speaker placement options. Thats honestly not that important for most people though, only if you need more flexibility without using a line level EQ.
For my design, I'm doing a HP to the M74A at 500 hz for the pair and shading one if these to flatten power response in the far field. One M74A would be enough if you don't need far field compensation for lower mids with a smaller baffle size.
The 3.5k turnover is also practical for the CTC spacing I chose. The flange from the T34B will be tucked under some of the flange of the M74As to line up acoustic centers properly. The mids have a set back VC, so that staggered placement scheme allows for a slightly tighter mid to HF spacing.
The 500 hz crossover was also chosen due to the woofer FR and off axis characteristics. The woofers have a fairly large dust cap which blends well with the mid domes in the off axis area. The Eminence Cannabass 10s play clean past 900 hz, so they're very suitable for crossing with the M74As at about 500 hz while still having enough overlapping response to blend using relatively shallow unsymmetrical filters. I don't want to go lower with the crossover because of power handling and excursion limitations. I prefer to have a good amount of headroom margine here. For typical music, the half power point for spectral power distribution is roughly 400 hz (unless its bass heavy dance music, rap, metal, etc).
The starting range practical for good dynamic range and power handling on a 75mm mid dome is about 500 hz 2nd order. You'd then run it out to its upper limit which allows for a smooth transition to a smaller HF dome. I'd choose 3.5k due to the off axis dip being in the most advantageous place, which allows for a natural sounding transition to the tweeter. You can choose a lower point for this, but I'd stick to 3.5k. Its also a natural pivot point for crossover EQing and implementing an adjustable HF pad. There are big advantages to using one of these in reflective rooms and treble heavy source material. A shelf EQ pivoting around this for the HF allows for versatile speaker placement options. Thats honestly not that important for most people though, only if you need more flexibility without using a line level EQ.
For my design, I'm doing a HP to the M74A at 500 hz for the pair and shading one if these to flatten power response in the far field. One M74A would be enough if you don't need far field compensation for lower mids with a smaller baffle size.
The 3.5k turnover is also practical for the CTC spacing I chose. The flange from the T34B will be tucked under some of the flange of the M74As to line up acoustic centers properly. The mids have a set back VC, so that staggered placement scheme allows for a slightly tighter mid to HF spacing.
The 500 hz crossover was also chosen due to the woofer FR and off axis characteristics. The woofers have a fairly large dust cap which blends well with the mid domes in the off axis area. The Eminence Cannabass 10s play clean past 900 hz, so they're very suitable for crossing with the M74As at about 500 hz while still having enough overlapping response to blend using relatively shallow unsymmetrical filters. I don't want to go lower with the crossover because of power handling and excursion limitations. I prefer to have a good amount of headroom margine here. For typical music, the half power point for spectral power distribution is roughly 400 hz (unless its bass heavy dance music, rap, metal, etc).
Good to know which dome mid you would choose for your project. Do you think this is a significant upgrade from the Scanspeak D7608 or more of an incremental upgrade? I would imagine that being alum/mag its a bit cleaner, more transparent? I know those are subjective terms but thats what I hear from a good metal dome tweeter, or alum cone woofer. Havent heard a metal dome mid yet.
Thank you.
So are you perhaps shading the lower M74 around 700Hz? With two M74s with flanges touching, 708Hz is where the C-C is 1/4 of wavelength.
With those two and the T34s crossed high you certainly won't be dynamically limited!
So are you perhaps shading the lower M74 around 700Hz? With two M74s with flanges touching, 708Hz is where the C-C is 1/4 of wavelength.
With those two and the T34s crossed high you certainly won't be dynamically limited!
@Troy Madden I don't consider the M74A to be a night and day upgrade or difference to the D7608. Its just more suited to my design goals, mainly regarding sensitivity and also diaphragm material being somewhat more analytical in the upper mids. I mainly wanted to build a highly sensitive speaker that wouldn't require much power to play loudly and have significant dynamic capabilities. Most hifi speakers don't exceed 90 dB/2.8V and I wanted to build a highly sensitive speaker (around 96dB/2.8V) equipped with modern low HD drivers.
With decent recordings, these things should sound accurate and highly resolving without sounding overly aggressive. They need to deliver big dynamics at minimal power compression and stress to the drivers, including the capability of playing very loud for longer periods of time.
The D7608s are definitely capable (in pairs) to dish out decent levels, but they're soft domes and will tend to be a little smoother and flattering. That's actually a good thing, but I wanted brutal accuracy and the ability to push the volume up to concert levels at lowest distortion levels. I also tried to avoid using compression drivers for this.
@Bill Brown I'm not totally sure exactly where and by how much to shade midrange driver output coverage without doing more sims or measurments. The baffle width is still up in the air as is the distance to floor, walls, etc. Your guess is pretty close for 1/4 WL limits. Again, it will depend on several other factors and criteria how the drivers will sum in this scenario.
I suspect the need for (and actually planned on using) variable shading, which could be dialed in/out as needed depending on speaker placement. Same holds true for HF shelf EQ. I like speakers that allow for flexible placement. Often times speakers will lock you into a specific placement option which isn't practical for several reasons. Having a few selectable options for lower midrange contour and an HF shelf above 5k is really handy. These are some things I tend to implement on more elaborate 3/4 way designs, especially when the drivers are more on the higher end cost side.
There are some instances where its appropriate and more practical to change a 3 way design to a 4 way. Having a separate midbass can be alot more versatile when trying to get the FR right for a given planned speaker placement, especially when the location is closer to a wall or floor. In my situation, I usually prefer to build floor standing 3 way setups, so there's enough enclosure volume to get more LF output or a lower tuning frequency.
With decent recordings, these things should sound accurate and highly resolving without sounding overly aggressive. They need to deliver big dynamics at minimal power compression and stress to the drivers, including the capability of playing very loud for longer periods of time.
The D7608s are definitely capable (in pairs) to dish out decent levels, but they're soft domes and will tend to be a little smoother and flattering. That's actually a good thing, but I wanted brutal accuracy and the ability to push the volume up to concert levels at lowest distortion levels. I also tried to avoid using compression drivers for this.
@Bill Brown I'm not totally sure exactly where and by how much to shade midrange driver output coverage without doing more sims or measurments. The baffle width is still up in the air as is the distance to floor, walls, etc. Your guess is pretty close for 1/4 WL limits. Again, it will depend on several other factors and criteria how the drivers will sum in this scenario.
I suspect the need for (and actually planned on using) variable shading, which could be dialed in/out as needed depending on speaker placement. Same holds true for HF shelf EQ. I like speakers that allow for flexible placement. Often times speakers will lock you into a specific placement option which isn't practical for several reasons. Having a few selectable options for lower midrange contour and an HF shelf above 5k is really handy. These are some things I tend to implement on more elaborate 3/4 way designs, especially when the drivers are more on the higher end cost side.
There are some instances where its appropriate and more practical to change a 3 way design to a 4 way. Having a separate midbass can be alot more versatile when trying to get the FR right for a given planned speaker placement, especially when the location is closer to a wall or floor. In my situation, I usually prefer to build floor standing 3 way setups, so there's enough enclosure volume to get more LF output or a lower tuning frequency.
So to all Bliesma M74A/B/S owners, you may want to check your mids for a potentially loose front mounting ring. This also holds the front mesh grille in place.
I've discovered that all 4 of my M74As had loose front flange rings. This is due to the powder coating inside the screw holes having built up in the threads and causing the 4 allen screws under the mounting flange gasket to bottom out too soon. This will also affect the dome clamping the VC together and could potentially allow.the VC alignment to shift if not caught before using the driver.
The problem is powder coating buildup in the screw holes keeping the screws from fully clamping the ring which sandwiches the carrier plate with the dome asy.
The flange screws were all tight when I checked them, but they didn't clamp the two halves of the driver housing enough. I found this out by testing them on my Clio setup when I heard some buzzing during the test sweeps. Putting pressure on the front rings stopped the buzzing.
I suggest either running a bottoming tape (M3x0.5) through the threads but DO NOT use a standard thread cutting tap for this!!! It won't reach the entire thread depth and may make the problem worse. If you don't have a bottoming tap, you can use a small bore brush instead ie. for cleaning a smaller caliber (.22) firearm. Alternately, you can also use shorter stainless M3/0.5 screws ie. 4 - 5mm length, just as long as they don't protrude out past the flange surface.
The potential buzzing issue won't show up if you've already mounted the driver, because the mounting screws will have clamped the whole driver together when they've been fully tightened.
This is honestly a minor issue but I'm kind of perplexed Bliesma would let something like this slip past QC. I'm not certain the VC could shift due to this, but I wouldn't want to chance it, so its better to be sure.
This unfortunately isn't the first time I had issues with Bliesma. One of my T34Bs arrived with the back chamber flopping around loose in the box. That was sort of a fiasco, but I managed to fix it myself with the proper adhesive and clamping method. Stan offered to repair them free of charge if I sent them to Germany, but I decided to fix them myself due to shipping costs and potential downtime. It was honestly fault of the place that sold them to me, how they packaged and shipped them. Bliesma tests these drivers for the purpose of matching them up in pairs, so they would have caught it before the drivers were sent out.
It just goes to show you its important to check everything even if you're dealing with a higher end product. Nothing is immune from having problems. Its just annoying when it happens.
I've discovered that all 4 of my M74As had loose front flange rings. This is due to the powder coating inside the screw holes having built up in the threads and causing the 4 allen screws under the mounting flange gasket to bottom out too soon. This will also affect the dome clamping the VC together and could potentially allow.the VC alignment to shift if not caught before using the driver.
The problem is powder coating buildup in the screw holes keeping the screws from fully clamping the ring which sandwiches the carrier plate with the dome asy.
The flange screws were all tight when I checked them, but they didn't clamp the two halves of the driver housing enough. I found this out by testing them on my Clio setup when I heard some buzzing during the test sweeps. Putting pressure on the front rings stopped the buzzing.
I suggest either running a bottoming tape (M3x0.5) through the threads but DO NOT use a standard thread cutting tap for this!!! It won't reach the entire thread depth and may make the problem worse. If you don't have a bottoming tap, you can use a small bore brush instead ie. for cleaning a smaller caliber (.22) firearm. Alternately, you can also use shorter stainless M3/0.5 screws ie. 4 - 5mm length, just as long as they don't protrude out past the flange surface.
The potential buzzing issue won't show up if you've already mounted the driver, because the mounting screws will have clamped the whole driver together when they've been fully tightened.
This is honestly a minor issue but I'm kind of perplexed Bliesma would let something like this slip past QC. I'm not certain the VC could shift due to this, but I wouldn't want to chance it, so its better to be sure.
This unfortunately isn't the first time I had issues with Bliesma. One of my T34Bs arrived with the back chamber flopping around loose in the box. That was sort of a fiasco, but I managed to fix it myself with the proper adhesive and clamping method. Stan offered to repair them free of charge if I sent them to Germany, but I decided to fix them myself due to shipping costs and potential downtime. It was honestly fault of the place that sold them to me, how they packaged and shipped them. Bliesma tests these drivers for the purpose of matching them up in pairs, so they would have caught it before the drivers were sent out.
It just goes to show you its important to check everything even if you're dealing with a higher end product. Nothing is immune from having problems. Its just annoying when it happens.
What concept do you need?
Ideally we don't pick drivers and then build something with them - we check what the speaker needs to do and then choose the right drivers.
Do you need wide or more narrow radiation? How is your room and listening distance. Only one listening seat or all over the place? Want to listen to the music or be surrounded by the music?
When wide radiation - linear wide radiation for similar listening experience also wide off axis or "shaped" to sound more friendly at high SPL? (which is often done and not a bad thing per se).
These leads to your concept, drivers and crossover frequencies.
Crossing at 3-500Hz is relatively easy. Wavelength are long (1/4 wavelength in the 25-20cm range), drivers radiate wide. It's just not as easy to measure precisely, in a normal room you won't get a measurement window long enough.
With active and 4th order crossover you can for sure go deeper as 500Hz, 430-450Hz is fine. Depends on SPL level cause THD will go up somewhat at extreme levels and these drivers. But one 3" could easy cope with 2x 12" in my design and didn't even show any compression when the 12"s already where done - so we are talking EXTREME levels before these get into trouble.
I did a 1:1 listening comparison of M74A, S and B. Made a special baffle and 2 presets matched to at least +-0,5dB. Tweeter T25.
I'd say I could hear a difference between S and A. The S membrane is pretty thin and designed to have some influence to the audio. And it does what you expect, make listening "easier". But still with lot's of details, just some nice touch on them. So that's not what I need for critical and neutral listening.
Difference between A and B in a speaker with complete crossovers ... was harder. I believe I still heard more natural details with the B version, a little "easier" to the ear. But price hike is pretty steep for that little difference, it's for the "last speaker project" kind of speaker.
So what would I chose? The T version 😎