Running the Scan-Speak 15w8530k00 full-range with no x-over
Any opinions/ suggestions on running the Scan-Speak 15w8530k00 full-range with no x-over?
I am currently using the Seas W12CY003 E0044 in a .25 ft3 Parts-Express cabinet with a tweeter/L-Pad added above 12kHz.
As you can see, the bass drops off much quicker than the Scan-Speak. It does have a phase plug so maybe better H-F than the Scan-Speak?
Madisound recommends trying a passive radiator to eliminate the 40hz bump but I like the coherency of a single driver. Wouldn't the P-R be like a separate bass driver and not be in-phase? That is 2 sound sources, not one so there will be sound wave interactions between the two.
That is why I am looking at the Scan-Speak for the flatter bass response - IF you can trust the published curves.
Interesting choice of drivers. These are both near 'state of the art' midbass drivers, somewhat remniscent of the KEF B110. The SEAS is a little more extended in the HF and somewhat smoother. The frequency response graphs are for the drivers mounted on a test baffle. The bass in these graphs is not the response you will get from a particular enclosure. The 40 Hz hump (Scan-Speak) is actually a response 'remnant' between cancellation notches, probably due to reflection from a nearby surface ('floor bounce'). There is no need to compensate for it. The extended HF of the SEAS (relative to the Scan-speak) is likely due in part to the phase plug. Both are fine drivers with a healthy Xmax, so some real bass is possible. However, that will not be achieved with a simple sealed box or BR. A passive radiator or some variant of a tuned pipe will likely provide good results. There will be some phase shift associated with either one, but it will be largely inaudible. You will likely need to pick up some modeling software and run some sims. Have fun.
Thanks Bob. Yes, these is noting like running a driver full-range with no x-over. The clarity is unmatched. Dynamics are surprisingly good even with my little 45wpc Zamp v3 which puts out 12 amps.
It is easy to hear the sound deterioration with a tone control or pre-amp. A haze is added and dynamics are reduced. I think maybe an active pre-amp would be needed to run the driver with a tone control.
I have been relying on Madisound and part-Express to model this for me. Attached are the FR with the speakers 51" and 41" out from the wall both 3 feet away and about 10 feet away at the couch. Sorry about the poor resolution but Diy won't allow 600dpi scans - too large.
Could you tell me what are the 3 lines on the Scan-Speak F-R curves? Are they 0 / 30 / 60 degrees or something else?
A couple of thoughts...
The 15w would probably need a correction circuit. I've heard it in commercial design with a 1st order crossover (cap and coil) and it sounded pretty darn good, but the 15w breakup was audible. Without the coil it probably would have been worse. I've also heard it in a diy design with a Hiquphon tweeter and it was the best small 2-way that I've heard. Both needed some power to come alive, but the bass was unbelievably good regardless of the small size of the speaker. I've never heard the Seas, but the curve looks much flatter.
I would surmise 0/30/60 on the SS curves. The 5" driver gives up a lot off axis which narrows the sweetspot and could deaden the sound.
In the alternative, SS has a 4" Discovery driver with a very flat frequency response curve, which may not need a correction circuit.
Or a Fostex or Markaudio 4" driver in one of P10's cabinet (designs).
Maybe I should stick with Seas, either passive radiator on the W12 or go with the W15 in a .5 ft3 cabinet.
I found this Discovery driver but it looks like it has a bad breakup too if run full range.
I should have written that the breakup was audible above normal conversation level and really assertive at a very loud level. At lower levels it was very listenable especially on well recorded acoustic jazz.
The 12w breakup appears quite controllable with a notch in a conventional 2-way crossover-ed speaker, but not for full range use.
The SS driver I was referring to:
Scanspeak Discovery 10F/8424G 4" Midrange 8 ohm: Madisound Speaker Store
Zaph measured the 4 ohm version:
FS is high so you will need some type of bass support.
"The slices are filled with damping glue, which dramatically reduces breakup
modes in the diaphragm."
I don't hear any with the Seas after break-in. I have used untreated paper coats before and I know what you are saying about nasty breakups. Coating with Mod-Podge or C37 has solved the problem. I wouldn't dare do that with the Scan Speak as looks like it already has a coating and could dissolve the glue.
For a 4" driver, the Seas W12 does not have the rising response curve and has a 6mm excursion vs 2.6mm excursion. It looks like the better choice. I liked the flat response of the 15W especially in the bass compared to the Seas
I have 4 options. Any opinions would be welcome:
In a .50 cubic foot cabinet:
6" .41 QTS Revelator with a vent
6" Seas Excel with a vent
In a .25 cubic foot cabinet:
6" .31 QTS Revelator sealed box
4 1/2" Seas Excel with a passive radiator
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