Yes, the MOREL MDM55 is indeed a nice and compact speaker, with a large dome, and good FR too 😎... But unfrotunately, the 89.5dB/W/m sensivity won't suit my needs, I guess... 🙁
https://www.morelhifi.com/product/mdm-55/
If I had a MDM55 for my 3-way orange-white bookshelf (pictured a few post before), instead of the small full-range I used, it would have certainly worked to match the 90dB/w/m level of the speakers. 😉
But for my 93-94dB/W/m 4-Ways monitor project, I'm afraid that the choice in suitable dome midrange candidates appears to be very limited... 😕
T
https://www.morelhifi.com/product/mdm-55/
If I had a MDM55 for my 3-way orange-white bookshelf (pictured a few post before), instead of the small full-range I used, it would have certainly worked to match the 90dB/w/m level of the speakers. 😉
But for my 93-94dB/W/m 4-Ways monitor project, I'm afraid that the choice in suitable dome midrange candidates appears to be very limited... 😕
T
@tubelectron Yes it sounds like you have found your preferred compensated FR curve.
A thing to note with the SS 3806 38mm mid-tweeter is it has a rising response. This actually a good thing when you factor in the midbass response being able to carry some of the output shyness down low with a shallow midbass LP slope. Adding the steeper HP on the 3806 with an offset slope can still retain the desired summed FR despite the lower sensitivity (to a point).
You can also try a bucking magnet on the 3806 to see if it will pick up another dB sensitivity. Thats obviously an uncertain thing which may not end up working out, so its not worth the risk of being stuck with an unsuitable driver.
You can also try the D7608 with extra magnet(s) - I've seen a little boost in sensitivity with this trick on a few other drivers, but I'm not sure how to quantify it without a full set of measurements, so stay tuned on that one. I'd have to gather the data on this with a new set of measurements and it may be isn't worth the hassle.
I have a big stash of smaller neo magnets I want to try adding to the D7608. Its hard to know what all changes when you mess with magnetic flux in different areas of the motor. The flux linearity and geometry in the VC gap can change unfavorably and mau increase odd order HD, so careful experimentation is needed.
A thing to note with the SS 3806 38mm mid-tweeter is it has a rising response. This actually a good thing when you factor in the midbass response being able to carry some of the output shyness down low with a shallow midbass LP slope. Adding the steeper HP on the 3806 with an offset slope can still retain the desired summed FR despite the lower sensitivity (to a point).
You can also try a bucking magnet on the 3806 to see if it will pick up another dB sensitivity. Thats obviously an uncertain thing which may not end up working out, so its not worth the risk of being stuck with an unsuitable driver.
You can also try the D7608 with extra magnet(s) - I've seen a little boost in sensitivity with this trick on a few other drivers, but I'm not sure how to quantify it without a full set of measurements, so stay tuned on that one. I'd have to gather the data on this with a new set of measurements and it may be isn't worth the hassle.
I have a big stash of smaller neo magnets I want to try adding to the D7608. Its hard to know what all changes when you mess with magnetic flux in different areas of the motor. The flux linearity and geometry in the VC gap can change unfavorably and mau increase odd order HD, so careful experimentation is needed.
I see @profiguy. I suppose you mean this about the rising response of the D3806 (green arrow below) :
The crossover strategy would be to let the Low-Midrange 8M60N "complement" the lack of level of the D3806, if I understand your purpose. Deduced from what we discussed about the slightly subdued response around 3.5kHz, well... Why not, after all ?
I did not though about the additional magnet tip, nor experimented anything serious in that field about speakers... A friend of mine did it years ago, and did not noticed great improvement in effciciency. But it was before the advent of the compact and powerful Neodymium magnets, and he used a dismantled ferrite, for which we all know that a significative part of the magnetic energy is lost when the front and back magnetic field plates are removed...
Then would the combination of both the FR/Xover trick and additional magnet tip be able to enhance the performances of the SS D3806 and/or D7608 ? 🤔
I stay tuned ! 😉
T
Adding magnets is hit and miss due to the design of the motor dictating how much effect it will have. An internal magnet motor like the D7608 has usually won't pick up much if anything, but an open magnet motor will usually benefit from a bucking magnet. The gain is however usually very subtle and every little bit can make a difference.
The response overlap working in your favor hinges upon the relative phase response between both drivers adding output. It doesn't do any good if they have opposing phase relationship to one another. It requires careful planning designing the crossover. This is where a good sim tool will be of great advantage.
Another thing to consider is just how much the minor amount of overlap between the LF and HF on a 3 way add to the net midrange output sensitivity. Obviously the more shallow the slope, the more overlap but there's alot more which comes into play fighting your efforts here. Using very shallow filters with a wide range of overlap is a recipe for combing and destructive interference when the driver spacing is less than ideal for the WL of chosen crossover frequency.
The response overlap working in your favor hinges upon the relative phase response between both drivers adding output. It doesn't do any good if they have opposing phase relationship to one another. It requires careful planning designing the crossover. This is where a good sim tool will be of great advantage.
Another thing to consider is just how much the minor amount of overlap between the LF and HF on a 3 way add to the net midrange output sensitivity. Obviously the more shallow the slope, the more overlap but there's alot more which comes into play fighting your efforts here. Using very shallow filters with a wide range of overlap is a recipe for combing and destructive interference when the driver spacing is less than ideal for the WL of chosen crossover frequency.
I see. It can be a plus, but no "magnetic miracles"...
Unfortunately, my PC-based measuring gear has became obsolete (thank you Windows), and I am still lagging to setup a new one... But in the S-// crossover formula that I use, all speakers are connected in polarity (= same cone displacement sense on attack) and with a 1st order configuration (= same phase of signal on decay, sustain, release), so it is already a good starting point - not to say prerequisites - against phase problems...
Of course, this doesn't prevent phase issues in the speakers themselves, but if these are used in a linear area and still be there at FC with a reasonable margin, there shouldn't be too much overlap irregularities problems. That's not always doable !
Yes, sure. That's why I also try to minimize the spacing between tweeter and midrange as best - in that sense, the MOREL MDM55 you mentioned is an interesting item, due to its small frontface - too bad for the moderate efficiency ! 😕
T
The only other large mid dome with any decent sensitivity and small flange is the Bliesma M74 series. They're just very expensive and hard to get here in the US. You can obviously get them from Solen, but they charge even more along with import duties if over $1000 (applies to Be version). The Alu version M74A is the best deal IMO for what you get.
Some older pro guys refer to that 4Khz ear sensitivity as "brain darts" . I've been cognitive to that for years too and design my systems to avoid it. I feel good when one of those guys comes over and comment, "how did you get rid of the brain darts". " Wow you really worked the brain darts out of this system". This would be on a horn system. One trend in tweeters I look for is low distortion with 3rd and higher being 10db below 2nd. Some domes are close to that now too. My system measure smooth through that region but slowly roll off to 5 or so DB at 10-20Khz.
Also of note. I recently bought a Dynacord\EV AC1 crossover with a 4Khz dip control. I use the AC1 but not the dip control. That's a well designed and implemented crossover. I paid $40.00 for mine. LOL
Has anyone heard the Yamaha JA-08B5 dome, from the NS-5000?
Or indeed the dome in the Revival Audio Atalante 5?
(I tried asking Revival Audio if they'd sell me a pair but they declined. I don't have a local dealer AFAIK, I don't know if a dealer would sell them as spares. They run 450 to 3.5k in the Atalante)
Or indeed the dome in the Revival Audio Atalante 5?
(I tried asking Revival Audio if they'd sell me a pair but they declined. I don't have a local dealer AFAIK, I don't know if a dealer would sell them as spares. They run 450 to 3.5k in the Atalante)
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Hi
Nobody mentions the use of Ferrofluid, I have lots of old(er) domes, e.g. the Visatons all have ffl in them, this is a problem, the fluid becomes sticky, completely changing response, replacing the fluid is always risky....a shame because I would like to experiment with my domes...
Nobody mentions the use of Ferrofluid, I have lots of old(er) domes, e.g. the Visatons all have ffl in them, this is a problem, the fluid becomes sticky, completely changing response, replacing the fluid is always risky....a shame because I would like to experiment with my domes...
I had the Revival Audio Atalante 5 last year, curious for the midrange dome; could buy them online as there was no commercial distribution yet at that time. Nice speaker, but I returned them. Also familiar with the ATC SCM40.
In my opinion the advantage of these dome midranges is somewhat overrated for domestic use; I preferred the SCM19 two-way over the SCM40, except for bass.
@profiguy: why don't you react on my question and PM??
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@scholl Yeah, that's exactly the issue with that frequency range. The center frequency can be anywhere from 2k to 5k depending on the physiology of the person. The shape of the ear and opening in the ear canal is what causes that for the most part. I did some research back in the 90s with an audiologist and a bunch of college students to map out individual sensitivity curves for about two dozen younger people to come up with a modified version of the loudness curve. The average center frequency of that resonance was 3.4k at a dip of 4 dB @ 100 dB average and would change another 2 dB or so with prolonged exposure to those levels.
In the case of mid domes, they usually have lower 3rd order distortion around the 3 - 4k range than most 25mm dome tweeters, making them better suited for higher end monitor designs. Higher end cone midbasses tend to have lower 3rd order distortion in the 2 to 4k range than most HF domes. The motor is what dictates most of the H3 content under the 1st breakup mode of any driver. Planar drivers are the worst offenders of elevated lower mid H3, which typically do significantly worse than many HF domes until excursion takes a back seat to diaphragm breakup.
In the case of mid domes, they usually have lower 3rd order distortion around the 3 - 4k range than most 25mm dome tweeters, making them better suited for higher end monitor designs. Higher end cone midbasses tend to have lower 3rd order distortion in the 2 to 4k range than most HF domes. The motor is what dictates most of the H3 content under the 1st breakup mode of any driver. Planar drivers are the worst offenders of elevated lower mid H3, which typically do significantly worse than many HF domes until excursion takes a back seat to diaphragm breakup.
Good point. I use the TW030WA11 which I don't think has ferofluid, I maybe wrong and SEAS 27TDC I know for sure doesn't have ferofluid. Of course the CDs I use don't have fero.
TW030WA11/12 don't use ferrofluid.
Most mid domes with ferrofluid have the higher viscosity type. Visaton uses a synthetic FF which is more stable long term. Most of the Seas anf Morel also use a synthetic FF.
I sometimes add FF to compression drivers with small VCs that see hard use. I haven't had any issues with it long term, just that it cut down with warranty claims. It barely affects FR when used correctly with the right amount.
Most mid domes with ferrofluid have the higher viscosity type. Visaton uses a synthetic FF which is more stable long term. Most of the Seas anf Morel also use a synthetic FF.
I sometimes add FF to compression drivers with small VCs that see hard use. I haven't had any issues with it long term, just that it cut down with warranty claims. It barely affects FR when used correctly with the right amount.
Sorry, I didn't get any PM notification from you and don't see any existing PMs. Not sure what went wrong.
Yes I agree with the SCM 3 ways that use the big ATC dome. It sounds good with a slightly higher xover than stock, but its still not as refined as the Bliesma M74S or A. These domes have lower THD and better sensitivity, but don't reach down as low as the ATC. The 2 way with their special dual suspension HF dome is very good. The SCM19 is a standard in British broadcast studios.
I also wanted to post about the Morel MDM55 and derivatives. They can be used slightly lower than usual if an LCR is used on the primary resonance.
The trick is to break them in first to lower Fs to where it settles in after initial use. I have a brand new set of MDM55s to get the exact before and after TSPs from. Last time I tested this, there was a difference of about 70+ hz in Fs. Thats enough to throw off the LCR calculation from a new dome. You should always test Fs when using an LCR notch and never use the factory given spec. Its going to be off most of the time.
The trick is to break them in first to lower Fs to where it settles in after initial use. I have a brand new set of MDM55s to get the exact before and after TSPs from. Last time I tested this, there was a difference of about 70+ hz in Fs. Thats enough to throw off the LCR calculation from a new dome. You should always test Fs when using an LCR notch and never use the factory given spec. Its going to be off most of the time.
Its tricky to replace FF in midrange drivers due to different viscosity typically chosen for a larger VC gap and higher peak excursion. If the old FF isn't completely removed l, you run the risk of incompatibility and breaking down the base carrier oil.
The bigger issue is obtaining FF with the correct viscosity. Most manufacturers use thinner FF usually meant for tweeters. It may not work as well for a midrange experiencing more excursion and could splash out of the VC gap during hard use.
A driver optimized for FF will have sufficient VC venting to avoid pressure differential between the dome and VC gap rear air space. This usually involves cross drilling the pole piece opening into the gap area and/or using a vented VC former.
Many compression drivers use a perforated surround, so they're usually well suited for FF retrofit. The increased magnetic flux of a CD keeps the FF in the gap more reliably and as long as the FF quantity isn't excessive and there's no question of material compatibility between adhesives used in the moving assembly, there's no other reason why FF can't be employed successfully in just about any driver. The biggest concern is splashing FF, but only if the VC gap is too wide.
I prefer a sealed box with the HM210CO. Ported makes the midrange to colored for my tastes.
I suppose if the dampening were sufficient and the box tuned correctly, it could work well. The issue is simply all the junk that comes out of most ports. That would ruin the otherwise superb balance and clarity in the mids this driver is capable of.
Thought I'd post some photos of what I built with the Hi-Vi DMB-A. Seas CA22RNX woofer and Vifa XT25SC50. I called it BM50 for 50 Liters.
Kind of a modern homage to the older BBC monitors I think sensitivity is around 90dB and 8 ohms so an easy drive for low power amps.
Kind of a modern homage to the older BBC monitors I think sensitivity is around 90dB and 8 ohms so an easy drive for low power amps.