Please vet this idea for a mid-high/high speaker
I have a small PA and I'm looking to upgrade the mids and highs.
My idea is to build two new boxes to handle the mid-high and highs, and to disable the tweeters built into the TOA cabs.To keep it small I'd like to use compression drivers for both mids and highs. I have abandoned that idea and now I'm thinking to use an Eminence 8" driver for the mid-highs.
I'd like to use the Selenium HC23-25 horn forboth mids and highs. I like its fairly short throw/wide dispersion and it's also pretty small.
Can you see any issues with this idea?
References:
Thanks for any wisdom you can bring to this upgrade!
I have a small PA and I'm looking to upgrade the mids and highs.
- The low end is 4x15" Eminence 3015LF4 drivers in bandpass cabs. They get ~500 watts each.
- The low-mid is 4x15" TOA (unknown drivers) in sealed cabs (SL15). They get ~250 watts each.
- The current tweeters are built into the TOA cabinets are piezo garbage from the 80's.
- The PA mostly gets used in my living room and also gets used at outdoor events with a few dozen people.
My idea is to build two new boxes to handle the mid-high and highs, and to disable the tweeters built into the TOA cabs.
I'd like to use the Selenium HC23-25 horn for
I'd use a Selenium D250-X GW for the midrange, something like 600-5000 Hz.- I'd use an Eminence Alpha-8MRA 8" for the mid-highs.
- I'd use a Selenium D220Ti for the high frequencies.
Can you see any issues with this idea?
References:
Thanks for any wisdom you can bring to this upgrade!
Last edited:
Thank you. I figured as much (seeing how uncommon that arrangement is on commercial speakers). I do like the idea of a sealed speaker, so that it's box agnostic. This Eminence Alpha-8MRA looks pretty fine.
Mostly for achieving low cost.
Dedicated mid and fast mid-bass are much welcome.
1. Good freq-resp from driver is 2 octaves, picking more is a compromise. So your PA must be at least 4-way. Sub+midbass+mid+high.
2. Better to XO and freq-tune before amplifiers. Commercials are limited in amplifier quantity.
3. You need to control directivity of the system at highs.
4. Do not put your HF driver too low due to higher displacement and poor linearity.
5. You need to achieve as low as possible freq-band overlap due to interference issues.
6. Understand equal-loudness curves and use them widely.
I'd re-think your choice of midrange driver.
A 2" diaphragm with a 1" exit isn't going to get loud at 600Hz.
For what it's worth, I'd simplify. A good midbass driver (something like the Faital Pro 12FH520) would go from the subwoofers up to a decent compression driver with plenty of output.
A 3-way system is much easier to get right than a 4-way.
Chris
A 2" diaphragm with a 1" exit isn't going to get loud at 600Hz.
For what it's worth, I'd simplify. A good midbass driver (something like the Faital Pro 12FH520) would go from the subwoofers up to a decent compression driver with plenty of output.
A 3-way system is much easier to get right than a 4-way.
Chris
Chris's idea is good but more expensive. I have done it both ways with good results, back when I was an active DJ in the '80s I build 2 sets of 3-way cabs with 15+ 8+1 and they always got compliments on sound quality. These days I have a double 15 over double 18" system utilizing 2" exit compression drivers covering everything from1khz up that produces stunning sound quality at very high SPLs. These cabs have a lot more expensive drivers in them... the comps alone retail for about $350ea, plus lots of power(3000w/ch over 3 bands) and 3-way DSP processing so it's not really a fair comparison.
Last edited:
I like the idea of simpler, but I'd like to improve the off-axis sound, and that's what led me to think about using a 15+8+1 setup for the highs rather than the 15+1. The 10" Faital wouldn't help much there, I think.
Now that I look at this I think 15+6.5+1 might be even better, if the 6.5 is loud enough to play nice with the 15 and the 1.
Here's a 6.5 that has a back that's conveniently sealed: Eminence Alpha 6CBMRA.
Now that I look at this I think 15+6.5+1 might be even better, if the 6.5 is loud enough to play nice with the 15 and the 1.
Here's a 6.5 that has a back that's conveniently sealed: Eminence Alpha 6CBMRA.
Last edited:
12” midbass will have poor directivity at most demanding 1-2 kHz range.
Yes. Check also something powerful like well-known 6ND410.
No. You will hit intereference issues at mids with clearly unpredicted result.
Asking for good off-axis response you better to think about column-type mid speaker in 200Hz-5kHz range.
I like it! They have a few other 6" mids also; I haven't digested the differences yet.
The 15", 6" and horn (for the compression driver) will all be centered vertically. Is that what you mean by "column-type"? That would cover ~150Hz - 20kHz.
I appreciate your help!
No. Put 8-16 pieces of Visaton FRS8M in a vertical column-array.
You will have ~120 degree horizontal angle with ~15-20 degree vertical angle with cylindrical wave in a horizontal plane. Those systems have ~1:1 Mms/Bl factors with ultrafast high-midbass response.
Yes, really expensive, but unbelievable space covering and sound fullfilling.
Do you need some descripting pdf’s?
Hey now, I like that idea too!
That'd be $80-$160 per side; not too bad. The 18sound driver was ~$140 so it's much the same.
I have the datasheet for the Visaton FRS8M, but if you have a pdf specific to the column array, I'd appreciate it.
Do these need to be in a sealed cabinet, or ported cabinet, or is it not critical?
Thanks for the suggestion!
Easiest way is to pick all of those: Audio Artistry
Simple, understandable and easy. Specially check radiation patterns in last (#6) paper. Straight unshaded array are last in ranking, but very easy to build-and-try to make decision about going further with existing drivers.
As you wish or as you need to couple with lower-midbass and subs. Also check Peecker Sound PSUT8TE drawings for additional ideas.
.... Or spend that money on a single 10" midbass that will have way more output with less distortion.
Column speakers with a subwoofer have a lot of problems, including very narrow dispersion above a few kHz, uneven HF "throw" where it's a line array at high frequencies but not low frequencies, and a lack of output below ~300Hz.
In terms of "space covering", this is 2x 10" midbass (3" HF driver) at around 85m from the speakers: YouTube
Chris
I'm definitely torn between a couple ideas. No matter what I'll keep using my four subs and my four 15" woofers, so I'm amply covered for bass and mid bass.
But for the mid-highs and highs I'm torn between:
Improving the off axis sound (at high SPL) seems to have a less obvious solution.
But for the mid-highs and highs I'm torn between:
- Just putting a compression driver and horn on the 15" cabinets. The sound quality will not be awesome, but it'll be better than the piezo tweeers currently living on the cabinets.
- Using one or two sealed back 5" or 6" drivers, plus a compression driver/horn per side. Theoretically I should get better off axis response by using small woofers for the mid-highs, and if I use a sealed driver I don't have to be particular about the size and shape of the cabinet. My research so far is not coming up with a sealed driver that can match the SPL of the 15" mid bass drivers though (calculated at ~127 dB peak at 3 feet.)
- Using one or two *not* sealed 5" or 6" drivers, plus a compression driver/horn per side. Theoretically I should get better off axis response by using small woofers for the mid-highs, and I have a wider selection of drivers than the few closed back drivers.
- Some sort of line array. With a compression horn also? Or not? Although I'm a pretty handy woodworker I don't have a shop anymore, so these are possibly unbuildable with my current toolset anyway.
Improving the off axis sound (at high SPL) seems to have a less obvious solution.
Last edited:
Yes, of course.
Something like 15MB650 will easily outperform 3” array in terms of nearfield pressure and upper-midbass/low-midrange band.
But lets see far from soundstage?
First.
15” will drop -6 dB with distance doubling
3” array will drop -3 dB with distance doubling up to 40-60 meters.
This will result in much more even loudness over stadium.
Second.
15” will need to run up to at least ~1,5-2 kHz for coupling with compression driver (keeping low distortion for last due to smaller displacement).
15” will need to be crossed over in a most audible region.
3” array will run through 300 Hz to 5-7 kHz
This will result in a much more clear midband perception.
Third.
15” in a 1,5-2 kHz band are ready for the massive cone breakup.
3” array will easily run up to 5-8 kHz
This will result in much worse distortion from 15” in a most needed band even keeping in mind lower displacement.
Fourth.
15” in a 1,5-2 kHz will have very narrow horisontal dispersion and bad coupling with horn-loaded driver in terms of off-axis polars.
3” array will easily run 300-5000 Hz with low high-freq dispersion falling.
This with first will help 3” array outperform 15” in terms of space-loudness fullfilling providing smaller space distortion and very natural reproduction.
Both of them have pros and cons, we could only know them and use them properly based on soundstage and PA-depth.
He-he...
No. Your 4x15” will work as omnisource, but your 5”-6” mid will be directed.
So at some distance they become equal in pressure and far your mid will dominate.
Yes, but X-oed a way higher with better results in terms of distortion.
Need for this are truly depend of your PA space dimensions - depth and width, of course keeping in mind placement abilities.
Last edited:
Every design has compromises so you have to chose you battles.
Horn mids have lots of output but can add a lot of distortion, depends on the driver and horn type. Use a larger diaphram driver and a wave guide horn and sound quality is very good but these components are 3-4 times more expensive
Column arrays only behave the way they do because of comb filtering... which is audible, and introducing that as the mid of an otherwise point source system creates a problem with dissimilar decay rates. If you balance the sound in the near field it will be all mids with muted lows and highs in the far field.
A single larger mid driver begins to beam at lower frequencies so the hi freq driver has to be crossed lower. Smaller mid drivers don't have enough output so that is why you often see the 6" mid being horn loaded.
The least problematic solution IMO is to use a slightly larger 8" mid, you get enough low/mid output to comfortably cross to a 15 at no more than 800hz and polar response is still wide enough to cross to the highs at 2khz. No it's not ideal but no solution is and don't forget there is overlap in the output of these drivers so the combined polar response is pretty good, and this solution is about as close as a PA speaker will ever come to producing Hi-Fi sound quality.
Horn mids have lots of output but can add a lot of distortion, depends on the driver and horn type. Use a larger diaphram driver and a wave guide horn and sound quality is very good but these components are 3-4 times more expensive
Column arrays only behave the way they do because of comb filtering... which is audible, and introducing that as the mid of an otherwise point source system creates a problem with dissimilar decay rates. If you balance the sound in the near field it will be all mids with muted lows and highs in the far field.
A single larger mid driver begins to beam at lower frequencies so the hi freq driver has to be crossed lower. Smaller mid drivers don't have enough output so that is why you often see the 6" mid being horn loaded.
The least problematic solution IMO is to use a slightly larger 8" mid, you get enough low/mid output to comfortably cross to a 15 at no more than 800hz and polar response is still wide enough to cross to the highs at 2khz. No it's not ideal but no solution is and don't forget there is overlap in the output of these drivers so the combined polar response is pretty good, and this solution is about as close as a PA speaker will ever come to producing Hi-Fi sound quality.
An externally hosted image should be here but it was not working when we last tested it.
That seems like the best option to me, I think. I do like that 6.5" midrange in the JBL PRX735 that you showed, but that horn doesn't seem to be available.
I'm back to regarding the Eminence Alpha-8MRA (8" sealed-back driver). I like that it's cabinet-agnostic, and it also has impressive sensitivity (100.9). Not to mention cheap! On the other hand, I used WinISD to model various 8" drivers in a sealed cabinet, and they seemed pretty forgiving of box volume, so maybe I can buy a generic 8" box and drop a driver in with good results.
Yeah in this case you don't care about the drivers low frequency response you just want to isolate it from the pumping action of that big woofer, so the box only has to be big enough to enclose the driver and some damping material. The Alpha8mra is easy and cheap but it will require some Eq, other drivers may have a little smoother response
Last edited:
Now I'm looking at the easiest way to mount the woofer and horn. I guess I could just mount them both to a plank of wood, but I'm thinking of cannibalizing some trash like these Rockville RSG8 speakers. They're $85 for a pair, including shipping. I'd toss the driver and tweeters, and cut a slot above the driver for the horn.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.