Just to give an idea what a 3" midrange is able to do and not to hijack this thread - my THD measurements over level for my prototype speaker with 2x12", 3", 1":
https://www.diyaudio.com/community/...th-a-modern-3-midrange-3way-prototype.408882/
https://www.diyaudio.com/community/...th-a-modern-3-midrange-3way-prototype.408882/
I actually meant to post this here but it ended up in another thread about 3 ways....
I have to generally agree with the higher tweeter xover from the mid being a benefit for those needing more clean SPL. I typically prefer higher xovers on tweeters than most people use, mainly due to the uneven rise in THD associated with lower xovers and small diameter domes.
My guidelines for crossing HF domes when used in higher SPL setups is the following -
19-25mm >4.5kHz LR2,>4kHz BW3
25-30mm >3.0kHz LR2,>2.7kHz BW3
30-35mm >2.5kHz LR2,>2.3kHz BW3
The exact frequencies depend on the type of music, specifically the crest factor, compression and bandwidth energy concentration. Obviously WGs also affect this.
The other factor is the perceived loudness curve around the 2 to 5kHz bandwidth, being smaller amounts of THD are more noticeable in this range to begin with. Phase jumps are really audible here. This is why I usually try to avoid crossing in this range, preferring the midrange driver to play uninterrupted.
Most of the time mid domes used for high output I will HP at -
38mm >1.8kHz LR2, 1.6kHz BW3
50mm >1kHz LR2, 800Hz BW3
65mm >800Hz LR2, 700Hz BW3
75mm >700Hz LR2, 600Hz BW3
Exact numbers vary with specific model drivers, VC xmax and overall power compression/ handling figures.
The D7608 can handle about 80W long term if xmax is regarded and the VC has a place to shed its heat.
On very high output monitors, I have used aluminum plates stacked behind the motor and extended out past the chamber. There isn't much metal mass on the driver to remove heat effectively, so the driver needs external cooling measures.
Ferrofluid works well with this dome. I've used 1100 mg of the Ferrotec APG312 FF in the gap of the D7608. It increases power handling by at least 25% if the motor is cooled externally. I've seen people use peltier coolers on mid and HF drivers mounted in sealed compartments managed with CPU style controller hardware.
The other thing to watch with most mid domes is dust accumulation. The Morel domes are VERY STICKY! If you have forced air heating, its very advisable to use some form of a grille. If you damage the dome trying to clean it, there's no VC replacement available and you're buying a new driver. Dust can degrade the sound if there's a lot of it
I have to generally agree with the higher tweeter xover from the mid being a benefit for those needing more clean SPL. I typically prefer higher xovers on tweeters than most people use, mainly due to the uneven rise in THD associated with lower xovers and small diameter domes.
My guidelines for crossing HF domes when used in higher SPL setups is the following -
19-25mm >4.5kHz LR2,>4kHz BW3
25-30mm >3.0kHz LR2,>2.7kHz BW3
30-35mm >2.5kHz LR2,>2.3kHz BW3
The exact frequencies depend on the type of music, specifically the crest factor, compression and bandwidth energy concentration. Obviously WGs also affect this.
The other factor is the perceived loudness curve around the 2 to 5kHz bandwidth, being smaller amounts of THD are more noticeable in this range to begin with. Phase jumps are really audible here. This is why I usually try to avoid crossing in this range, preferring the midrange driver to play uninterrupted.
Most of the time mid domes used for high output I will HP at -
38mm >1.8kHz LR2, 1.6kHz BW3
50mm >1kHz LR2, 800Hz BW3
65mm >800Hz LR2, 700Hz BW3
75mm >700Hz LR2, 600Hz BW3
Exact numbers vary with specific model drivers, VC xmax and overall power compression/ handling figures.
The D7608 can handle about 80W long term if xmax is regarded and the VC has a place to shed its heat.
On very high output monitors, I have used aluminum plates stacked behind the motor and extended out past the chamber. There isn't much metal mass on the driver to remove heat effectively, so the driver needs external cooling measures.
Ferrofluid works well with this dome. I've used 1100 mg of the Ferrotec APG312 FF in the gap of the D7608. It increases power handling by at least 25% if the motor is cooled externally. I've seen people use peltier coolers on mid and HF drivers mounted in sealed compartments managed with CPU style controller hardware.
The other thing to watch with most mid domes is dust accumulation. The Morel domes are VERY STICKY! If you have forced air heating, its very advisable to use some form of a grille. If you damage the dome trying to clean it, there's no VC replacement available and you're buying a new driver. Dust can degrade the sound if there's a lot of it
Can I highlight once again that the source of distortion matters here. Critical to mid-range "transparency" is the reduction (or elimination where current drive is used) of magnetic non-linearities that are most audibly prevalent in this band, even before we make adjustments for loudness perception or masking.
I wholeheartedly agree with the comments on phase, but make the point again that these issues can be audibly more prominent in stereo reproduction than they are when auditioning with a single loudspeaker.
These two issues are not 75mm dome specific, however, and probably best left to another thread...
But with regard to dome-specific issues, I am intrigued as to why an LR2 alignment would be preferred over LR4 (in an active set-up I presume?), where the latter alignment appears to offer only advantages over the lower order version in this application?
While I am on here, an interesting fact that has always mystified me re 75mm soft domes...
When fabric domes are produced, they are yellow (at least the ones supplied by a well-known fabric dome manufacturer were). A black dye is then added by all the 75mm driver manufacturers of which I am aware, although I think now you might be to purchase pre-dyed ones too?
But I have measured an experimental pair of 75mm domes without the dye added. Sure they emerged after the damping substance was applied in a particularly ugly shade of green, but they measured significantly better than the black ones.
Whether the improvement from removing the dye is audible is a matter I would leave others to judge, but we appear to have a widespread manufacturing "standard" that requires driver diaphragms to be black, even where that produces a measurable disadvantage.
When fabric domes are produced, they are yellow (at least the ones supplied by a well-known fabric dome manufacturer were). A black dye is then added by all the 75mm driver manufacturers of which I am aware, although I think now you might be to purchase pre-dyed ones too?
But I have measured an experimental pair of 75mm domes without the dye added. Sure they emerged after the damping substance was applied in a particularly ugly shade of green, but they measured significantly better than the black ones.
Whether the improvement from removing the dye is audible is a matter I would leave others to judge, but we appear to have a widespread manufacturing "standard" that requires driver diaphragms to be black, even where that produces a measurable disadvantage.
I haven't heard of this driver. Does anyone in the US actually carry their products? I doubt its available as a separate driver to purchase. Looks very promising from a design standpoint.
Yes, I meant 1100 ug. I got my metric increments mixed up somehow.
http://toneimports.com/
But as said before here: I had Atalante 5 here. The midrange was on par with ATC SCM40.
@soundbloke My practical observations with crossover points are implied from the electrical filter standpoint, not the acoustic rolloff. I also usually avoid more complex filters in the passive domain. There may be benefits to using steeper slopes on a case by case basis, but I personally try to keep the filters simpler for various reasons. The main one is acoustic driver integration. Steep slopes don't sound as good with larger driver CTC spacing. The vertical stereo image bounces around more abruptly and is very noticeable on large multi driver systems. The clean and seamless acoustic overlap on transitioning drivers relies on accurate phase tracking between them, otherwise the image is unstable.
Also, perceived distortion vs theoretical limitations on their audibility is very subjective. There are no hard rules to what can be detected by out hearing based on numbers alone. The type of music, playback volume and acoustic environment all affect the audibility of THD. I had this argument with people who cited research using average, casual listeners' perceptions instead of more advanced, highly educated listeners trained in the audio field, who could pick up on finer details. I'm only interested in the perception of much more musically educated listeners who could consistently pick up on very small changes in what they hear. I don’t care on how easily you can fool the average listener, because in some ways you can actually get away with murder from an audio reproduction perspective. Just from that standpoint alone, most people would likely care less whether they listen to a cone or dome midrange, let alone an actual pair of decent speakers or a TV soundbar.
While I appreciate your input, I'm not really in the position to debate various intricacies of theoretical reasoning as to how some things I'm posting measure up to hard proven science. Alot of the things I'm citing are the result of personal perception of various applications of design using dome midranges and subjective comparisons between various related drivers. I'm not the kind of person who leans on large quantities of measurement data to prove a point. Measurements matter, but so do the actual listening impressions, including the possible reasons for perceiving them.
I created this thread for the purpose of sharing ANYTHING pertaining to dome midranges. This includes personal observations, sharing of designs, info on drivers, practical implementation and ideas to improve/modify them. I didn't want the thread to be clogged up with alot of scientific theory debate / argumentation and hard analysis of data. Thats what usually kills a thread like this. No offense intended to those who prefer to argue about hard data. This isn't intended to be the thread for it
I wanted this to be a practical guide and collection of info on how to implement dome mid drivers within their practical limits, not argue and banter about their validity of existence. Its sad these drivers aren't represented more and there isn't much useful practical information out there.
I specifically wanted to compile a practical knowledge base of useful info, so that anyone who is on the fence with dome midranges can try them without much risk ie. Some may not agree with many of the things I'm saying from a theoretical scientific standpoint. I'm only trying to share my experiences and help others with implementing dome mids into their own designs.
Also, perceived distortion vs theoretical limitations on their audibility is very subjective. There are no hard rules to what can be detected by out hearing based on numbers alone. The type of music, playback volume and acoustic environment all affect the audibility of THD. I had this argument with people who cited research using average, casual listeners' perceptions instead of more advanced, highly educated listeners trained in the audio field, who could pick up on finer details. I'm only interested in the perception of much more musically educated listeners who could consistently pick up on very small changes in what they hear. I don’t care on how easily you can fool the average listener, because in some ways you can actually get away with murder from an audio reproduction perspective. Just from that standpoint alone, most people would likely care less whether they listen to a cone or dome midrange, let alone an actual pair of decent speakers or a TV soundbar.
While I appreciate your input, I'm not really in the position to debate various intricacies of theoretical reasoning as to how some things I'm posting measure up to hard proven science. Alot of the things I'm citing are the result of personal perception of various applications of design using dome midranges and subjective comparisons between various related drivers. I'm not the kind of person who leans on large quantities of measurement data to prove a point. Measurements matter, but so do the actual listening impressions, including the possible reasons for perceiving them.
I created this thread for the purpose of sharing ANYTHING pertaining to dome midranges. This includes personal observations, sharing of designs, info on drivers, practical implementation and ideas to improve/modify them. I didn't want the thread to be clogged up with alot of scientific theory debate / argumentation and hard analysis of data. Thats what usually kills a thread like this. No offense intended to those who prefer to argue about hard data. This isn't intended to be the thread for it
I wanted this to be a practical guide and collection of info on how to implement dome mid drivers within their practical limits, not argue and banter about their validity of existence. Its sad these drivers aren't represented more and there isn't much useful practical information out there.
I specifically wanted to compile a practical knowledge base of useful info, so that anyone who is on the fence with dome midranges can try them without much risk ie. Some may not agree with many of the things I'm saying from a theoretical scientific standpoint. I'm only trying to share my experiences and help others with implementing dome mids into their own designs.
@daanve Thats good to hear. I expected it to be decent based on what I could tell from their info. Its nice to see more people use dome drivers for mids and I think people are starting to catch onto why these drivers are IMO better suited to reproducing this delicate frequency range. In reality, dome drivers impart less overall distortion and coloration than cone drivers of similar range when implemented correctly.
I'd like to hear of any observations with the old Infinity poly domes. I know by now most of these have failed from age and material fatigue, so it would be interesting as to what good options are out there as replacements. The Infinity Beta and RS range are very sought after in some parts of the world, so I'm sure someone has some solution to fixing these mids.
If you have DSP available (?) then achieving phase tracking is fairly trivial - provided you stick to an operating band below diaphragm break up. I am stumped as to what you mean by "vertical stereo imaging", but certainly there are audible consequences from large spacings and multi-driver systems, which is why LR4 should then perform better than LR2, all else being equal. Thiele notched crossovers are well worth considering for large spacings that cannot be avoided, or when using multiple domes.
This ought to be the subject of another thread, but it is very insightful. Our hearing is highly non-linear because of our capability to learn - either by purposeful training or more passive, unintentional experience. This has a significant factor in assessing audibility, and learning to identify the "glare" of current dependent non-linearities serves a s a perfect example. Once identified, you will hear it with ease.
That is exacty what my posts have been aimed at. I have a substantial amount of experience of using 75mm domes from not long after they first appeared. I believe they still provide the best compromise where overall high fidelity is the target. Much knowledge has been acquired since their inception and I trust my imparting some of my knowledge here helps those sufficiently enthused to build loudspeakers based around such domes.
If somebody states that one driver sounds better than another, or one system sounds better than another, my instinct is to find out why. I trust that instinct is shared amongst contributiors here, even if the answers require a certain scientific rigour.
Nevertheless, I will refrain form posting in this thread anymore.
Are you referring to (Dr.) Kurt Muller produced domes? If not, I am really curious to learn who else produces these 75 mm diaphragms?
Hey simply speakers sell a replacement for those mids on there site you should check out simplyspeakers.com
https://www.simplyspeakers.com/replacement-speaker-dome-midrange-m-330.html here is the link if your interested
If your old beloved car is a dead end street , kill it! You can't live your whole live with a car that is only be used by strange guys with a strange hobby! Same for midranges that have some qualities but have a dead end street too ...
thankyou I'll do some more searching I'm all about searching for the best midrange I can get .the bass I have is already pretty good ha
@soundbloke There's no reason for you to completely leave the discussion here. I just didn't want it to turn into one of those other threads on here which get taken over by a flood gate opening of endless data and arguing about why their theory is more valid than other's. I meant for it to stay somewhat approachable for people who just wanted practical info they could implement without needing a degree or PHD in loudspeaker design. Your info is welcome and I wanted to make that very clear. Of course its your decision.
My approach to crossover design is more in the passive filter realm. DSP is practical and versatile without a doubt. I like analog filters because I often listen to analog sources, so the goal is to retain a fully analog signal path. Drivers which require complex DSP to make them behave dont appeal to me. My theory is that if a driver is well behaved by design, it won't need all the extra DSP.
The remark about the vertical stereo image is meant to depict the perceived height of a phantom sound source. Its a product of the sum output of the individual drivers and how homogeneous the separate driver's output signals combine. Relative phase should be smooth, not suddenly shift undetected (not visible due to smoothing), especially in the overlapping response between drivers. This is much harder to achieve due to off axis response not tracking the same phase as on axis does. IMO shallow filter slopes result in better three dimensional stereo imaging if the driver remains somewhat linear in the rolloff regions. Steep filters don't blend as coherently, especially if one is trying to bandaid ragged or sudden rolloff behavior with them. The phase errors are magnified with higher order filters, unless the driver's natural rolloff combines favorably with the electrical filter response. The phantom stereo image height also becomes blurred when drivers are spaced incorrectly on the baffle. Diffraction and floor bounce obviously are another influential component, but they can be optimized with better baffle design, layout and with strategic room treatments.
My approach to crossover design is more in the passive filter realm. DSP is practical and versatile without a doubt. I like analog filters because I often listen to analog sources, so the goal is to retain a fully analog signal path. Drivers which require complex DSP to make them behave dont appeal to me. My theory is that if a driver is well behaved by design, it won't need all the extra DSP.
The remark about the vertical stereo image is meant to depict the perceived height of a phantom sound source. Its a product of the sum output of the individual drivers and how homogeneous the separate driver's output signals combine. Relative phase should be smooth, not suddenly shift undetected (not visible due to smoothing), especially in the overlapping response between drivers. This is much harder to achieve due to off axis response not tracking the same phase as on axis does. IMO shallow filter slopes result in better three dimensional stereo imaging if the driver remains somewhat linear in the rolloff regions. Steep filters don't blend as coherently, especially if one is trying to bandaid ragged or sudden rolloff behavior with them. The phase errors are magnified with higher order filters, unless the driver's natural rolloff combines favorably with the electrical filter response. The phantom stereo image height also becomes blurred when drivers are spaced incorrectly on the baffle. Diffraction and floor bounce obviously are another influential component, but they can be optimized with better baffle design, layout and with strategic room treatments.
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