Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

Something like that. Still, with only a very few others, at the top of the breed after all this time. Oh for a larger room. Still, that's what sledgehammers are for. :devilr: TBH, out of preference though, I'd always go for a driver run WR & supported at the extremes with dedicated units these days.

I still say WRT motors though, the more powerful the better (can you tell I'm getting more & more interested in compression drivers Greg?). Simplistic, but there's still some truth there, amongst the caveats.
 
Scottmoose said:
TBH, out of preference though, I'd always go for a driver run WR & supported at the extremes with dedicated units these days.

I still say WRT motors though, the more powerful the better (can you tell I'm getting more & more interested in compression drivers Greg?)

You're 'preaching to the choir'! 😉

Right on, think about how well damped our vocals are, so it's going to be hard making an electro-mechanical device to rival it, though a high CR horn driver with a Qes around 0.1 coupled to a long/large enough horn does an excellent job and why I used ultra low Qes (0.16) 15" horn loaded drivers mated to a high CR mids/HF horn during my peak listening years. Today though, the three way Unity plus pipe horn sub is a better way to do it if $$, space isn't an issue, but even a single low Q 15" properly mated to a compression horn gets you 95% there.
 
FR8, FR8C MLTL cab dwg.

Found this in my computer, but I don't remember where Dave posted it and can't find it on any of his sites:
 

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pjanda1 said:

I also just want to point out the effects of shorting rings. I've seen so many mention the Qts as being responsible for the different HF response of the Fostex 206/207 and the 166/167. If it a slightly higher Qts meant such dramatically reduced hf response (which is better in this case), then many higher Q vintage drivers (or even the B200) shouldn't have any treble at all. But they do, and I don't understand why folks tie Qts and hf extension together in the way they do.

So you're saying that the '6' series has shorting rings and the '7' series doesn't?

Anyway, shorting rings allow the driver to be all it can be, so to speak, since it doesn't have a rising impedance to 'choke' its natural high frequency response.

Qts OTOH only affects the BW below the driver's mass corner which is a floating point defined by Qts for a given Fs and vice versa. Perceptually though, the lower the mass corner (higher Qts), the wider a driver's flat BW response (ignoring any rising impedance, break-up modes and/or any dustcap and/or whizzer affecting the response), so all else being equal a higher Qts driver will be tonally balanced over a wider BW than a lower Qts one.

Bottom line, given the budget and a choice between otherwise similar T/S spec drivers, I'm going to choose the one with the flattest impedance since there's no such thing as too wide a natural BW IMO (as opposed to an artificial break-up modes one).
 
lousymusician said:
The group that met in Sacramento yesterday seemed to like them.

Hi Bill - was that you at the Sacramento meet? My buddy John said he heard a pair of older Hemp 8s there in a TL enclosure and was very impressed.

Was that you?

John heard my FR8c drivers in Planet 10 Dave's Demetri cabinet in Denver. We didn't have the Demetri fully dialed in yet, but they seemed to impress a lot of listeners - none the less.

BTW, are your Metronomes the ones I've seen photos of on the web?
 
lousymusician said:



The BIB is an option if you have good corners (or at least a wall) against which to load them, and can handle the size and weight.

My room is too small for the BIB's. I have the Hemp Acoustics FR8's (the full name is FR810HQDIY) in the Metronome cabinets. I think they work quite well. They are decidedly smaller than the BIB's, and will work away from a corner. I'll have them at Burning Amp today, maybe you can get an unbiased review from an attendee. The group that met in Sacramento yesterday seemed to like them.

Bill

The BIBs may, in fact be too large, testing the limits of the WAF. The Metronome is my next personal fav. Thanks all for the advice.

Bill, I do have that model of the Hemp Acoustic drivers. Can you suggest a starting point for the BSC? Is a zobel network required and if so, what values did you use for the components?

Cheers,
Ryan
 
panomaniac said:


Hi Bill - was that you at the Sacramento meet? My buddy John said he heard a pair of older Hemp 8s there in a TL enclosure and was very impressed.

Was that you?

John heard my FR8c drivers in Planet 10 Dave's Demetri cabinet in Denver. We didn't have the Demetri fully dialed in yet, but they seemed to impress a lot of listeners - none the less.

BTW, are your Metronomes the ones I've seen photos of on the web?


That was me, and those are my Metronomes on the Frugal Horn site. I think there may be one other pair of Hemps in Metronomes out there, but I somehow think there aren't too many more than that.


RKH said:


The BIBs may, in fact be too large, testing the limits of the WAF. The Metronome is my next personal fav. Thanks all for the advice.

Bill, I do have that model of the Hemp Acoustic drivers. Can you suggest a starting point for the BSC? Is a zobel network required and if so, what values did you use for the components?

Cheers,
Ryan

Mine have a 1 mH inductor paralleled with, IIRC, 9 or 10 Ohms. I tried values from 5 to 13 or so. No Zoebel. Coincidentally, this is about the same network some Visaton B200 owners use. (Not really coincidental, I used that as a starting point, and it worked well enough that I stopped there!).

There was a measurement room set up at the Sacto meet. I took a photo of the measured FR of the Metronomes as displayed on the laptop. There's a dip centered at 900, and the top is rolled off, but overall I think it's fairly smooth for a minimalist full ranger speaker. 😀

I suspect a supra baffle would help with the dip. If I only had a lathe (a brain, a heart, the nerve...).

Bill
 
GM said:


So you're saying that the '6' series has shorting rings and the '7' series doesn't?

Bottom line, given the budget and a choice between otherwise similar T/S spec drivers, I'm going to choose the one with the flattest impedance since there's no such thing as too wide a natural BW IMO (as opposed to an artificial break-up modes one).

6 v. 7, yup, that's how I understand it. Flat impedance certainly shows a low distortion motor. However, the rising impedance you get without the shorting ring counteracts the natural rising response of speaker drivers, as the amp puts out less current into those higher impedances. This is the phenomenon that allows loudspeakers to have a somewhat flat respone without a circuit to compensate, right? There are some neat impedance/response graphs in Dickason's book, but you can see it if you compare the 206/206 and 166/167 graphs.

Dave: nice work on the Enabling. Is that now standard treatment at chez Planet10?

pj