Midwoofer suggestion for two ways

[Audiophile100%]

I'm undecided between these two:

SB Acoustics SB17NRXC35-8
or
seas ER18RNX

what are your suggestions
thank you very much

[JonMarsh]

I've used the ER18RNX in a couple of projects, one which was a two way with a waveguide loaded tweeter (Modula MT XE). It worked quite well- it is a low Q driver, works best in a bit larger box with a slightly EBS tuned alignment, in my opinion.

Distortion performance of the driver is pretty good, as shown in this complete system plot.



Unevenness in LF response is due to room effects, long measuring gate, etc. Near field is quite smooth.

[Audiophile100%]

thank you jon,
and sb ?, do you know it ?
i'm very intrested to it, it maybe promising....

what about the bass of er18 ?, someone says that is tiny....

[JonMarsh]

If you put the ER18RNX in too small a box, the bass will certainly be tiny... :W

As always, I'd suggest an evaluation of possible configurations with Unibox or WIN ISD or similar tools. There are certainly drivers that will play lower in smaller boxes, but then you always give up sensitivity. Sometimes you give up upper midrange performance, too, with a heavier cone.

I don't have any experience with the SB17NRXC35-8, but the data looks good, looks like a more modern design, and the impedance curve is quite promising, which might yield lower upper end distortion than the Seas. The Seas has slightly greater Xmax, and greater cone area, as it is a 7" woofer nominal, not 6-1/2". Only way to really know is measure both, I think. The Madisound recommendations for box sizes and porting don't jibe with my experience with the ER18RNX. I'd suggest 25-28L net (plus allowing for driver volume) and Fb in the range of 35-40Hz.

[5th element]

http://www.audiogurman.com/3.htm#sb17nrxc35-4

And below it is the mineral filled poly cone variant. Certainly excellent performance all around.

[augerpro]

If you do go with the SB consider using the poly version. I played with both versions in 15cm and liked the poly better since the breakup didn't intrude into the music at higher levels like the paper version did (IMO).

[Audiophile100%]

i'm talking about trated paper, i'm non intrested to PP
thank you

[augerpro]

Any particular reason you only want paper?

[Audiophile100%]

i prefer its timbre, but i know the pp is much rigid

[5th element]

What sets different materials apart, sound wise, is how they go through breakup. In these regards you will be wanting to cross over any driver well before they break up proper. With any 6.5" driver the overall diameter basically sets the highest acceptable xover point to around 2kHz, preferably a little lower if the tweeter can manage it. In this regard both drivers have excellent performance, however the paper version has a worse edge surround resonance. The paper versions break up is also, as augerpro points out, pretty ugly, the pp driver is far better controlled and will be much easier to work with as a result.

These days paper and pp are rather loose terms and by no means describe how a cone is going to perform. Paper can vary from super soft well damped, to rigid and resonance prone. The same is true for pp, where what the cone is filled with and how it's formed/cooled will determine how soft or rigid the cone is. PP will always have a lot of internal damping however, now matter how stiff it is made. This is a good thing.