There was a nice and gentle downward curve in my sim. and it was about 88dB for the woofers, and 85+dB for the SB65. Should be a very easy speaker to listen to.
I just designed a WWMWW with four of the SB15’s and a 5MR450NDY as wide band mid tweeter. It’s a TL with F3 of 40Hz and F6 of 33Hz and solid 90dB at 2.83v and 1m sensitivity after baffle step losses. Seems to look pretty good as 1st order BW XO at 1100Hz electrical but acoustic at 800Hz. This is a custom order for a DIYA member who says he may post a build thread. It sure looks interesting though. Max SPL is 113dB at 33Vrms.
4ft tall x 10in wide x 15in deep. Huge tapered TL vent exit (like PMC) at bottom.
Not surprisingly, the vertical polars look pretty decent.
4ft tall x 10in wide x 15in deep. Huge tapered TL vent exit (like PMC) at bottom.
Not surprisingly, the vertical polars look pretty decent.
This will be fun - you might want to start a new thread for this once drivers get in and you start cutting wood.
The narrow 5in wide dimension on the minor axis, and TS parameters reminiscent of the RS225-8 were what got me interested. Instead of two drivers as mid woofers and two as bass woofers with a tweeter on top like the Elsinore 3 way, this is a much simpler design in keeping with the FAST concept with all four woofers in series-parallel for enhanced sensitivity and running them wide band with a first order XO that’s very much like the 10F/RS225 speaker of this thread. Being a solid 90dB after a 5dB baffle step loss, the 10F did not have the sensitivity or power reserve to keep up. So I decided to use the PRV 5MR450NDY-8. It’s about 94dB sensitive andbhs a great wide bandwidth. Perfect for a passive 1st order XO. Initial simulations are with driver TS parameters assuming perfect piston behavior, breakup peaks have to be dealt with using notch filters.
My initial sims assumes a rather wide 11in (ext) cabinet as I had RS225’s in there. Not shown here, but reducing cabinet width by 1in allowed max power to go up a bit as cone motion was more controlled. It’s a tapered TL with about 100in length. Drivers arranged as WWMWW where M is PRV 5MR450NDY in a 2 liter Dagger that hopefully will not obstruct the TL too much. Here is max SPL assuming 11 in wide cabinet. At 10in it went up to 113dB at 33Vrms.
Notice the nice XO at about 800Hz and good transition over the baffle step region (red curve is only output from one of four drivers):
Here is the predicted impedance for the woofers:
Probably some more damping inside the TL is needed flatten those peaks.
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The only speaker I ever finished myself was using sandpaper, boiled linseed oil, a rag to apply oil, and more sandpaper and boiled linseed oil, and then furniture wax. It turned out great though - not too hard.
That's a very nice driver, and a first look, being aluminum 8in with a phase plug appears to resemble an RS225 in silver. Let's take a look at the frequency response before we even look at the TS parameters. Here is the SEAS:
Note that there is a sharp drop off at 1000Hz, the XO is at about 800Hz to 900Hz (acoustically) on the 10F/RS225 and being a first order XO, needs a smooth wide bandwidth across the XO region. Also, that sharp peak at 4kHz would really need some serious notch filtering - but indicates this driver was not meant to operate with a low order XO into the mid-range.
Here is the frequency response for the RS225-8:
Looking at the T/S parameters for the SEAS:
Re=6.1ohms
Le=3.76mH
Qms=3.13
Qes=0.29
Vas=93L
fs=21Hz
mms=40g
Sd=220cm2
xmax=14mm(p-p) or 7mm (one-way)
For RS225-8:
Re=6.5ohms
Le=0.86mH
Qms=1.46
Qes=0.51
Vas=56.3L
fs=28.3Hz
mms=35.8g
Sd=214cm2
xmax=7mm (one way)
The main large differences are the Le, Vas, Qes, and Qms - basically a very different driver electro-mechanically. I don't think it will work with the same XO. However, if you measured it and used a simulator program, you could derive a new XO and perhaps move the XO point lower, to say 500Hz (acoustically) to stay farther from the 1000Hz drop-off.
So, this re-affirms an observation that I have had regarding the RS225-8: it is a unique driver that is unmatched at any price and by any brand.
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Thankyou for that in-depth reply. I realise it is seldom the case of using an alternate driver for a given design, but like your first few observations....the Seas seemed to have a little bit in common with the RS!..
I'm not able to measure and XO design is very new to me and hard to get my head around so maybe this is a little too much for me at the moment!
I'm not able to measure and XO design is very new to me and hard to get my head around so maybe this is a little too much for me at the moment!
Thanks!
Thanks and no, I've installed magnets in my previous speakers and never ever put the grills on. So I figured why bother with these.. I love bare drivers
