B&C 12CXB coaxials

[MikeS 0]

A little over a year ago a older good audio friend picked up some B&C 12CXB's off eBay. He kept emailing me saying that he really liked these coaxials, and that I'd better jump on a pair before they were gone.

I kinda held out for awhile, because folks tend to change their point of view over a period of time with audio gear.

He never did, and kept razzing me to get a pair. He finally worked a deal with the seller for a I can't pass it up kind of deal.....

We both have listened to the B&C 12CXT, and liked that coaxial, but both prefer the bit more lively sound of the compression tweeter used with the 12CXB. Older ears I suppose.

I mounted and experimented with port tuning in these cabinets I bought from the guy for 10 bucks years and years ago, and have done quite a bit of bracing and other work to them. Even though they are butt ugly......I may stain them real, real dark. I have grill frames for them, and some old vintage cloth.

They have been my experimentation enclosures for the last 4-5 years, basically.

Last summer, I tried port tuning at around 32Hz or so with one port. It worked ok, and I thought I had decent bass.

The lack of bass made the tweeters seem hot, and I was padding them down.

I eventually picked up some Klipsch LaScala cabinets, to fix up and check out the W horn bass bin sound. And the B&C's got shoved aside for six months. Three weeks ago I pulled them out again, and listened again.

Thin bass......I emailed my audio buddy who had been egging me to tune them higher the whole time.

He said I should notice shallow bass with a occasional peak at the vent tuning, and he was right, whayada know....

So I downloaded WinISD and poked around with the graphs. They are a 3.98 foot internal volume box. I went for 50Hz box tuning. WinISD recommends a two foot box tuned around to 60Hz for the flatest response, IIRC.

I'm using two ports in each cabinet, three inches diameter, and a little under two inches length.

With a sine wave oscillator (600 ohm out with 1K resistor in series) and a VTVM, one cabinet has a fb of 46-47Hz, with the other aty 49-50Hz. Like a fool, I didn't check fs with the drivers when they were out of the cabinets.

Dunno why the 3Hz difference, I think driver fs.

I have a little over 2.5 pounds of polyfil in each cabinet, and took out almost a half pound to see if the fb would raise on the 46Hz fb cabinet. It didn't do nothing to fb.

Response by ear with music and sine wave sweeps seem to indicate that both speakers sound the same and rather hard to tell the difference between the two.

Bass response is rather excellent to me now, the tweeters don't seem hot, and I'm running them unpadded.

I set the active crossover to my SVS subwoofers at 50Hz. It blends real well this way.

They sound fine with good bass without subwoofers, even at low level listening. Stereo imaging is real nice.....

Mike

Edited June 24, 2008 by johnecon2001
fixed pics

[MikeS 0]

Good lord......I give up.....you'll just have to hit the links.....

Edited June 24, 2008 by MikeS

[johnecon2001 82]

Good lord......I give up.....you'll just have to hit the links.....

Not necessarily..

[dem beats 1,223]

nice boxes!

I am jeleous. I want to do some home audio projects.

[MikeS 0]

Not necessarily..

Thank you very much mister super moderator guy!

This next sunday I get to go a visit a guy up north of here who just picked up two pair of Tannoy System 15 DMT II monitor speakers.

I would guess they will be hooked up to a McIntosh MC275 (PP with KT88's), with the Mac SACD player.

It will give some sort of idea how my B&C's compare to those big monitors. They may be trounced, or they might be rather close. I'll have to go by aural memory, however.

Point source imaging, more amp and music friendly than Klipsch, excellent bass.......I can live with this. I do need to build tower cabinets with the drivers more ear level....someday. Maybe I'll build risers for now.

Mike

[MikeS 0]

I went and visited another audio buddy up north of here yesterday. He wanted me to listen to his Tannoy system 15 DMT II monitors.

They were lashed up to a McIntosh MC275, with a McIntosh SACD player.

Excellent sounding speakers. Smooth as butter, imaging from hell, strong tight bass that can get deep as well.

I couldn't drag along the B&C 12CXB's to compare, maybe I can con the guy into it someday.

Going by aural memory, the Tannoys have a smoother upper midrange and high range. They are tuned to 38Hz, and can get down deeper than my B&C's, which are tuned to the upper 40Hz area.. I expected that, because it is a 15" driver.

The Tannoys have larger sound/soundstage, but not by too much compared to the B&C 12CXB coaxial.

Imaging is about the same. The B&C sensitivity is right along with the Tannoy, so output levels are the same.

My B&C's bass in my scab cabs is not quite as tight, but rather close.

It isn't bad for a 12" compared a 15".......

I get good strong deep tight bass, just not quite as deep or as tight as those Tannoy cabinets.......which are really, really well built. Hate the color, however.....

So I think I'll try to do some more crossover work and smooth the upper mid and treble response somehow, and do a little more cabinet stiffening and damping work.

Good enough for my poverty strickened soul.

I'll never afford a Mac MC275 or the SACD player, wish I could.......But I got this ol' ALtec 345A EL34 PP power amplifier slowly getting a full rebuild. Ain't no Mac, but I think it'll be a good sounding amp.

The guy had another system with Klipschorns, with another MC275 amplifier, a Alesis studio CD player with a Benchmark DAC. I liked that DAC.....I want one....it had a volume control. I could use about anything for a transport, and input it right to the amp....like a linestage almost. Considering I listen primarily to CD's, that would be a nice option.

I wanna DAC with a volume control. I won't swing a Benchmark, they run from $800 used to $1200 new...ouch.....

Of course the Altec amp has volume pots. pondering.......

Edited July 1, 2008 by MikeS

[///M5 2,833]

Nice write up.