3 way high SPL sealed studio monitor
Edit - Changed the title of the thread to better reflect the current ideas.
Hello,
Apologies, I have started similar threads before, but got confused and waylaid by other projects.
I build music studios. I have built several pairs of custom speakers for my studio builds... mostly derived from proven designs. I have a superficial understanding of some things, but I can be flummoxed easily.
I want to build a sealed, 'limited range' (100 Hz - 20 KHz) monitor which will function well @ 2m-4m listening distances. The accepted studio protocol (per ITU 775) is an equidistant triangle between the speakers and the listener, with L&R angled @ 30 degrees.
In my current demo room, I have Tannoy DC12i (with a coaxial 12" driver) and custom subwoofers with AE TD15H drivers. One of my main problems is that the stereo imaging is much more stable further back into the room from where I'm sitting (the speakers are about 9' apart and I'm sitting @ about 8' - this is 1' ahead of the theoretical "sweet spot"). I'm hoping that a smaller mid-woofer will beam less and widen the sweet spot.
I already have a pair of B&C DE250s in SEOS 12 waveguides. I'd like to use the DE250s for sure (they sound absolutely great to my ear, in a pair of 4 Pi speakers I built), but I'm willing to consider a smaller waveguide if it will help me increase my XO frequency (between mid-woofer and CD), for a wider sweet spot at a closer listening distance...
System will be tri-amped with Class D amplifiers, and managed by MiniDSP 4x10HD, with analysis and tuning help from REW.
At this time, I'm thinking that bass duties will most likely be handled by a JBL 4645c, simply because it is very inexpensive here. Luckily, it will serve as a great stand for the mid-woofer/HF speaker and bring the listening axis point up to the recommended 4' above floor level. I'm also thinking about a Peerless by Tymphany STW-350F in a custom sealed enclosure, but that is for another thread.
Right now I am focussed on the mid-high component.
Goals:
* 82 dB average / 102 dB peaks @ 4m, from ~100 Hz to ~18 KHz (some active Eq may have to be applied to achieve this, of course). (85/105 dB is the film standard - but for smaller rooms, the kind that these speakers are intended for... 82/102 should be sufficient.)
* Suitable for listening distances of 2m-4m.
* Sealed enclosures that can be easily customised to different rooms by varying the dimensions, but keeping the internal volume constant.
At this time, my questions are -
* Will a pair of Eighteen Sound 6ND430s per side do the job? What alternatives should I consider?
* If so, how high can I cross them over to the DE250s in SEOS12 waveguides? Or should I consider keeping the XO point as low as possible, in order to minimise interference problems between the mid-woofers?
* Will a smaller waveguide such as the Eighteen Sound XT120 be preferable for a higher XO point (~2 KHz)
* Are there any fundamental flaws to this approach?
Thanks in advance,
PS: I'm stuck in a total lockdown/quarantine situation. I can't access my PC which is in my studio, in which I have WinISD - the only speaker design software I'm familiar with... Pity there seems to be no similar software for Mac...
Edit - Changed the title of the thread to better reflect the current ideas.
Hello,
Apologies, I have started similar threads before, but got confused and waylaid by other projects.
I build music studios. I have built several pairs of custom speakers for my studio builds... mostly derived from proven designs. I have a superficial understanding of some things, but I can be flummoxed easily.
I want to build a sealed, 'limited range' (100 Hz - 20 KHz) monitor which will function well @ 2m-4m listening distances. The accepted studio protocol (per ITU 775) is an equidistant triangle between the speakers and the listener, with L&R angled @ 30 degrees.
In my current demo room, I have Tannoy DC12i (with a coaxial 12" driver) and custom subwoofers with AE TD15H drivers. One of my main problems is that the stereo imaging is much more stable further back into the room from where I'm sitting (the speakers are about 9' apart and I'm sitting @ about 8' - this is 1' ahead of the theoretical "sweet spot"). I'm hoping that a smaller mid-woofer will beam less and widen the sweet spot.
I already have a pair of B&C DE250s in SEOS 12 waveguides. I'd like to use the DE250s for sure (they sound absolutely great to my ear, in a pair of 4 Pi speakers I built), but I'm willing to consider a smaller waveguide if it will help me increase my XO frequency (between mid-woofer and CD), for a wider sweet spot at a closer listening distance...
System will be tri-amped with Class D amplifiers, and managed by MiniDSP 4x10HD, with analysis and tuning help from REW.
At this time, I'm thinking that bass duties will most likely be handled by a JBL 4645c, simply because it is very inexpensive here. Luckily, it will serve as a great stand for the mid-woofer/HF speaker and bring the listening axis point up to the recommended 4' above floor level. I'm also thinking about a Peerless by Tymphany STW-350F in a custom sealed enclosure, but that is for another thread.
Right now I am focussed on the mid-high component.
Goals:
* 82 dB average / 102 dB peaks @ 4m, from ~100 Hz to ~18 KHz (some active Eq may have to be applied to achieve this, of course). (85/105 dB is the film standard - but for smaller rooms, the kind that these speakers are intended for... 82/102 should be sufficient.)
* Suitable for listening distances of 2m-4m.
* Sealed enclosures that can be easily customised to different rooms by varying the dimensions, but keeping the internal volume constant.
At this time, my questions are -
* Will a pair of Eighteen Sound 6ND430s per side do the job? What alternatives should I consider?
* If so, how high can I cross them over to the DE250s in SEOS12 waveguides? Or should I consider keeping the XO point as low as possible, in order to minimise interference problems between the mid-woofers?
* Will a smaller waveguide such as the Eighteen Sound XT120 be preferable for a higher XO point (~2 KHz)
* Are there any fundamental flaws to this approach?
Thanks in advance,
PS: I'm stuck in a total lockdown/quarantine situation. I can't access my PC which is in my studio, in which I have WinISD - the only speaker design software I'm familiar with... Pity there seems to be no similar software for Mac...
Attachments
Last edited:
The 18Sound 6ND430 is an excellent driver, and I'd expect it to keep up just fine. Be careful of the 5kHz peak, and you won't have any trouble from those.
I'd consider orienting the pair of 6"s vertically, though, to minimise interference as you move in the horizontal plane.
Chris
I'd consider orienting the pair of 6"s vertically, though, to minimise interference as you move in the horizontal plane.
Chris
Placing two mids side-to-side like that will narrow the horizontal directivity (but not vertical). Unless you cross over to the tweeter rather low - under about 1.3kHz - you'll end up with some strange power response due to wildly varying directivity around the cross over frequency. For your application I see no reason to use two mids in any case. One should be more than capable of the SPL you want in your small-ish room and since you are going active, driver sensitivity makes little difference.
In any case I think a 6" mid is a bad match with a 12" waveguide. To get smooth directivity you'll need to cross over pretty high (>2.5kHz) which negates any reason to use a 12" waveguide. I think a better mid choice would be a 10" or 12" mid. You would do very well with a JBL 2123 mid. No longer available new, but they are plentiful and fairly cheap (for what you get) on the used market.
In any case I think a 6" mid is a bad match with a 12" waveguide. To get smooth directivity you'll need to cross over pretty high (>2.5kHz) which negates any reason to use a 12" waveguide. I think a better mid choice would be a 10" or 12" mid. You would do very well with a JBL 2123 mid. No longer available new, but they are plentiful and fairly cheap (for what you get) on the used market.
Thank you Chris...
Maybe something like the attached image, then...? I suspect MTM will be more complicated because of the additional interference between the mid-woofers - but it will be nice in a way - I can get the acoustic axis (the centre of the waveguide in an MTM, presumably) bang at the correct height...
Attachments
MTM doesn't give additional interference within the typical 20 - 30deg ( vertical ) listening axis as long as the mids are tight-packed to the horn/waveguide.
- That's no worse than any other monitor using a horn/driver combo that's mated to a single larger sized mid-woof.
OTOH, ( with MTM's ), the resulting nicely centered image( virtual point source ) is well worth the effort to make work ( IME + IMHO ).
🙂
Yep, +1 for MTM. It effectively maintains directivity control to a lower frequency than the HF horn itself can provide.
Chris
Chris
I already have the SEOS12 - I suppose it will not perform well with a ~2K XO?
If so, how about an 18 Sound XT120 with XO around 2K to 2.5K?
My current SEOS12/DE250 is in a sealed box with Eminence 2512 drivers - very nice speaker, but without sufficient toe in/listening distance from speaker, imaging is not stable for my use case... No fault of the speaker at all... Hence the desire to move to a smaller mid-woofer with a higher XO point, hoping for a wider sweet spot at closer distances...
EarlK and Chris... thanks...
How does the attached image look?
Any guesses on the performance of the SEOS12 vs the 18 Sound XT120 in this application?
How does the attached image look?
Any guesses on the performance of the SEOS12 vs the 18 Sound XT120 in this application?
Attachments
I have both the SEOS 12 and XT120. Both are good. I would not bother changing out your SEOS in this case.
You should keep a lower crossover point (1khz). This will work better for close listening.
You should keep a lower crossover point (1khz). This will work better for close listening.
Last edited:
Image Stabilization ( within a control room ) is as much ( or more ) about acoustic design ( for that room ) than just about a monitors polars or it's overall flatness // curve within a controlled environment.
Do you have any acoustic ( REW ) files to share ( from your any recent installs ) ??
I can tell you from ( my own listening ) experience that one wants an "excess Group Delay " profile/trace to be absolutely clean ( straight line ) between ( say ) 700hz up to over 10K.
Without that clean line , imaging gets more + more compromised ( as the "spikes" get denser and taller > as displayed at 1/48th smoothing ).
🙂
Do you have any acoustic ( REW ) files to share ( from your any recent installs ) ??
I can tell you from ( my own listening ) experience that one wants an "excess Group Delay " profile/trace to be absolutely clean ( straight line ) between ( say ) 700hz up to over 10K.
Without that clean line , imaging gets more + more compromised ( as the "spikes" get denser and taller > as displayed at 1/48th smoothing ).
🙂
An MTM with a horn for high frequencies is, IMHO a problem. Even tightly packed, two 6" drivers plus the height of the SEOS waveguide will require you to cross over somewhere under 1.5kHz. Maybe as low as 1kHz if you want stable frequency response sitting down and standing up. Even then, you end up with some weird directivity discontinuity between the mids and the tweeter in the horizontal axis. At 1.5kHz the mids will have close to 180° coverage horizontally while the tweeter will be around 90°. This kind of step change in directivity makes for odd power response and (here's where the real problem lays) you cannot fix that with EQ or in the crossover. I think XDir (google it) can illustrate this.
There is a reason you don't see pro speakers built like this (you do see MTMs using big drivers and large horns crossed over very low which fixes the directivity mismatch problem, but not with 6" mids).
I still don't understand why you are fixated on a 6" mid with that waveguide and more to the point, why two of them.
There is a reason you don't see pro speakers built like this (you do see MTMs using big drivers and large horns crossed over very low which fixes the directivity mismatch problem, but not with 6" mids).
I still don't understand why you are fixated on a 6" mid with that waveguide and more to the point, why two of them.
I use a 6ND430 with a Wavecore TW030WA11 at 2KHz with very good results. The 2K crossover to the waveguide creates a good off access response determined by the TW030WA11 . They have precise imaging and wide sound stage, little sibilance and a nice deliberate articulation.
For my taste I run the TW030WA11 2.5db down so the TW030WA12 would have worked very well. YMMV
The midbass crossover is active at 350hz to AE TD15S 250watts on the top 500 on the woofers for CD playback. I rarely run more than a watt but rock out to peaks in the 10s of watts. I buy the big amps cheap and like them but could get away with a punchy 50 watts\ 20 watts.
I hear very good things about the eighteen sound drivers but the TW030WA11 are impressive too. If you don't need the extra output a single 6ND430 to TW030WA12 will simplify the system.
For my taste I run the TW030WA11 2.5db down so the TW030WA12 would have worked very well. YMMV
The midbass crossover is active at 350hz to AE TD15S 250watts on the top 500 on the woofers for CD playback. I rarely run more than a watt but rock out to peaks in the 10s of watts. I buy the big amps cheap and like them but could get away with a punchy 50 watts\ 20 watts.
I hear very good things about the eighteen sound drivers but the TW030WA11 are impressive too. If you don't need the extra output a single 6ND430 to TW030WA12 will simplify the system.
Last edited:
I'm looking at a ~6" mid-woofer because I think it will beam much less at mid frequencies, than a larger woofer, potentially leading to a wider sweet spot. If crossed over @2-2.5 KHz into a suitable waveguide, I'm hoping to achieve something approaching constant directivity. A single 18 Sound ND430 will give me an average of around 101.5 dB @ 4m - that is peaks of about 107.5 dB, giving me about a 5.5 dB headroom over the required peaks of 102 dB @ 4m.
However I wonder if it will be able to accomplish this down to 100 Hz in a sealed enclosure. Maybe I should consider the 8" Beyma 8BG51 or something similar, crossed over at 2.x KHz to an XT120 waveguide?
I already have the DE250s and SEOS 12s. I would definitely like to use the DE250 as it (another pair) has been abused for over 6 years in a 4Pi design I built, and still sounds super robust, yet smooth (of course, it was paired with a 2226H, crossed over @~1KHz (if I remember correctly). So I would like to use the DE250 - also it puts out 114 dB average @ 4m, giving me more than enough headroom for what I want to achieve.
I am amenable to changing the CD to the 18 Sound XT120 (or some other) as it's recommended crossover frequency is >2KHz.
The Wavecor TW030WA11 looks nice and is priced nice, but it will deliver average of 95 dB at 4m... This falls slightly short of my requirement, and I'd certainly like to have some headroom over what I need...
Attachments
Right now I am using a 6ND430 as midrange, the horizontal directivity matches at 2.8kHz to the XT120 waveguide. Sounds good (with LR4 slopes) if the 5kHz peak is properly notched out, if anyone is interested.
Good to hear. What are you using for LF/sub and where is the crossover to the midrange at?
The woofer is an Eminence Kappalite 3012LF, crossed at 320Hz which is exactly 1/4 wavelength C-C distance in my situation. Higher crossover still sounded good, but lower I didn't liked for whatever reason.
Based on inputs received so far on this thread and another I had started earlier, I have come up with two ideas. I seek your comments on them.
Idea 1 - SB Acoustics SB34NRX75-6 XO @ ~220 Hz to 18 Sound 6ND430 XO @ ~2.8 KHz to 18 Sound XT120 / B&C DE250. I am not able to calculate the SPL capability of the 12" woofer (confused with their data, my inexperience), but I hope that it will be in the ballpark of what I need. But the woofer has other things going for it and comes highly recommended... I'm not comfortable with the 220 Hz crossover (or anything above ~100 Hz), because too many of the most relevant fundamental tones are happening around there. Also I fear that I will miss content in the lowest octave, though the speaker will, in most cases, be flush mounted into a hard wall and I can hope to get some reinforcement from there... If executed properly, I suspect this could be more finessed than my next idea.
Idea 2 - Peerless Tymphany STW-350F XO @ ~100 Hz to Faital Pro 8PR200 XO @ ~2.2 KHz to 18 Sound XT120 / B&C DE250. I would like this to be the better idea as I imagine it will have more headroom, and I won't have to XO at a frequency I'm not comfortable with. I hope I will be able to Eq the sub (Linkwitz Transform?) to reach into the lowest octave...
Idea 1 - SB Acoustics SB34NRX75-6 XO @ ~220 Hz to 18 Sound 6ND430 XO @ ~2.8 KHz to 18 Sound XT120 / B&C DE250. I am not able to calculate the SPL capability of the 12" woofer (confused with their data, my inexperience), but I hope that it will be in the ballpark of what I need. But the woofer has other things going for it and comes highly recommended... I'm not comfortable with the 220 Hz crossover (or anything above ~100 Hz), because too many of the most relevant fundamental tones are happening around there. Also I fear that I will miss content in the lowest octave, though the speaker will, in most cases, be flush mounted into a hard wall and I can hope to get some reinforcement from there... If executed properly, I suspect this could be more finessed than my next idea.
Idea 2 - Peerless Tymphany STW-350F XO @ ~100 Hz to Faital Pro 8PR200 XO @ ~2.2 KHz to 18 Sound XT120 / B&C DE250. I would like this to be the better idea as I imagine it will have more headroom, and I won't have to XO at a frequency I'm not comfortable with. I hope I will be able to Eq the sub (Linkwitz Transform?) to reach into the lowest octave...
Attachments
Last edited:
Well, both options looks viable. But recently I searched on the net for 8PR200 measurements and found some and saw that driver doesn't have the low distortions as the 6ND430 and the distortion profile is dominated by 3rd harmonic and 5th harmonic is relatively high too, if that means something to you.
But maybe the 8PR200 tolerates the a low crossing better.
Robsan-DIY | Faital Pro 8PR200
But maybe the 8PR200 tolerates the a low crossing better.
Robsan-DIY | Faital Pro 8PR200
The 2226 with DE250 is a pretty good combo. What was it that you didn't like about it that makes you long for a mid? I know you mentioned "a wider sweet spot", but at 1kHz (where you were crossing over) the 2226 has ~70° beam width. How much wider do you really want to go (and to what end)?
Just for fun, and since it's so cheap for you (I'm assuming you still have the 2226s), why don't you try the 2226 with the SEOS-12/DE250 combo. Or even better, the DE250 with the B52 PHRN-1014 waveguide. That's a very well liked combo around here.
BTW, you SPL calculations for your CD/horn are only right for one particular frequency. I highly doubt your DE250 will have 100db/W sensitivity at 10kHz, for example. In any case I am sure that any CD/horn combo will have more than enough SPL capability in any domestic situation (unless hearing loss is a goal ;-)
Just for fun, and since it's so cheap for you (I'm assuming you still have the 2226s), why don't you try the 2226 with the SEOS-12/DE250 combo. Or even better, the DE250 with the B52 PHRN-1014 waveguide. That's a very well liked combo around here.
BTW, you SPL calculations for your CD/horn are only right for one particular frequency. I highly doubt your DE250 will have 100db/W sensitivity at 10kHz, for example. In any case I am sure that any CD/horn combo will have more than enough SPL capability in any domestic situation (unless hearing loss is a goal ;-)
I built the 4 Pis for someone else as a part of their studio build (pic attached). I don't have a clear memory of imaging in that room, but now that you mention it, I never noticed it to be a problem there... Hmm... (Pic is from before the studio was finished.)
On a vaguely related note, 2226H can no longer be bought for DIY builds in India... They were damn cheap (~$220), and all the local killjoys started building their own cabinets and selling them with fake JBL labels. JBL killed it when they found out...
(FWIW, I never charge anyone for building speakers. My carpenters just build them along with the rest of the studio, and my clients as well as specific designers (where applicable) are aware of this... Here is a page on my website, in this regard.)
In my own studio (built more recently), I used SEOS 12 w/ Eminence Deltalite 2512 and I had this image stability problem when listening in front of the apex. I set them aside when I got a good offer on a pair of Tannoy DC12i, and I have the same problem. Truly excellent imaging at the back of the room and unstable imaging up close. I also have a pair of One Pi speakers mounted (tweeter down and angled towards the sweet spot) above my Tannoys... they have 8" woofers and silk dome tweeters (no WG) and their imaging is much more stable at close quarters... Hence my presumption that an 8" or smaller mid-woofer will give me better imaging. (You can see a pic of my room with the inverted One Pi speakers... The Tannoy's are and the SEOS 12s were flush mounted behind the grille cloth.)
And here is an image of my cat sitting just below my Tannoy's, on the protruding ports of the custom AE TD15H based sub. Shortly after this pic, he proceeded to tear the rubber surrounds of the sub... hence prompting me to revaluate my entire speaker situation...
Attachments
Last edited: