New Reference Speakers with Full/Wide-Range Driver

A few thoughts

This discussion has been very interesting and I would like to add some of my subjective observations.

I have been playing with some el cheapo open baffles that I screwed together recently and it has been very educational. Mine use 8" philcos from an old SS console. I was afraid that they would be too beamy but something about the OB configuration makes that fear unfounded. I was shocked at how stable the freq. response and imaging is as I move around my 14x14 room. I have added 1" dome tweeters crossed at 5K 6dB/8va and they have eliminated any problem with beaming yet still provide for excellent clarity. I originally wanted to roll the tweeter in at 10K but I didn't have the right caps for that. The current crossover seems to work pretty well though.

The oval idea is intriguing but alas I only have one 6x9 so can not experiment with that. I think that 8" is the absolute minimum for a round full range based on my admitedly limited experience. In a box I would expect the beaming to be an issue however (so I don't use boxes :D).

My sysem runs the 8s full range with no crossover. Alone I get useful output to about 60Hz but in actual use I eq. flat and use a sub to reduce excursion on the 8s so that they are not really doing much below 80Hz. They do however produce enough down to low C (65Hz) to make bass vocals very clear to my ears. Ideally I think that any highpass or correction on the mid should be at line level.

My sub is mediocre at best but still provides sufficient impact for my room.

I have had several "Holy Crap" moments in the last few days that I think point to our current path being a very proper one. For example.

Rossini overtures played quite loudly. The immediacy, impact and presence of the bass drum puncuation of the strings was so powerful that I just about wet myself. Now I have used this sub before with regular three ways with no where near this result. I conclude that it is more than the bass providing the "you are there" impact. There is something about the open baffle fullrange approach that really resonates throughout my whole being. Unfortunately I am not smart enough to analyze what it is.

Some classic rock has also opened my eyes. Naturally the Boston (don't look back and third stage) has real impact. The distant storm effects on Third Stage were incredibly clear and convincing. However, the real surprise was that when playing the Styx (paradise theater) and some Steve Miller Band I heard all kinds of subtle things going on in the background that I have never clearly heard before. I was actually able to understand what the background voices were saying during the special effects sequences.

Regarding efficiency I have been unable to put more than one watt per channel (not counting the sub) into them without the volume level approaching painful. It is still clear and the drivers show no sign of distress it is just too loud to tolerate. This is efficient enough for my taste. They are a little bit forward at times but I bet a bat of fiberglass draped over the back would fix that too assuming that it did not ruin the imaging.

I like the idea of a pro 10" OB mated with a better sub but my current system cost me exactly $10 plus the $150 sub and I don't really feel compelled to do much more at this point other than to tidy it up by properly mounting the tweeters and adding some paint and grills. Any other improvements needed should just be some tweeks of the tweeter caps, and acoustic treatment of the backwave. Well of course a better sub is a fairly high priority too as I don't have quite enough extension for "Also Sprach" yet. ;)

My next course of action is to do some serious listening to acappella recordings. I could really get into this frugalphile thing.


P.S. The word that was bleeped out there did not rhyme with pit.

Yeah, 6"x9" car drivers are generally pretty good in OB. I run a set of Kenwood KFC-6949s (which were just discontinued at retail, though the 6950s on Kenwood's site look identical), which are bicone 6"x9" full rangers. They're solid to about 70Hz, useable to about 60Hz on 20"x16" baffles on my desktop (driven by a T-Amp; the 4 Ohm load gives you about 9.5watts useable before distortion sets in, so at 92db sensitive and being nearfield, they don't really use any power), though I can EQ that down to 50Hz/45Hz (I use an E-Mu 0404 soundcard as source, and its drivers can do all sorts of EQ and processing; have to be careful with this as it will put my T-Amp into distortion easily if all I do is boost the bass).

Generally, though, 6"x9" drivers are similar in surface area to 8" rounds, so their performance should be similar, all things being equal (when are they ever, though, eh?). I have seen some larger bicones in the pro audio area. One of the 10"ers has been modified by Zu in some of their commercial designs. I believe they're rated 40-9000 by the manufacturer, but after being modified with phase plugs, Zu specs them at 40-12000. Of course, those particular drivers aren't suitable for OB (Qts is much too low; Zu runs them sealed in their designs). I had seen a more recent entry that's a 12" pro driver that might be more appropriate, especially if modded with a phase plug (I'd seen it at Parts Express). Run something like that full range with a super tweeter and then a high Qts 12" or 15" driver driven by a small plate amp (use the amp's crossover controls to tune it to the full ranger), and you could really have something in an enclosure that's not much more than a board with some holes cut in it.

Fostex FT17H on top

I run a setup similar to what you're doing. A PR65Neo from max speakers, (great driver) with a first order to fostex FT17H on top at about 5 k. Works real nice, with dispersion tapering appropriately, IMHO. But I roll off the mid at about 200Hz, which is where the sealed box rolloff begins.

Lots of people prefer the pricier, not as linear, fostex horns, but then have to pad them down. I am quite happy with the FT17H in this role, and it requires no padding to match the drivers (imagine that, skip an extra crossover component or two!)
hey Dave

picked up a pair of ferrite Delco 6x9 for `$25 shipped

maybe for trying Karlson's AP9C

gotta deal with kidney cancer and bigly blood sugar first


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