BLH cabinets made from 1952 Jensen plans/plus DIY BL250 Ultraflex

[Mike Stehr]

http://aafradio.org/audio/Jensen_TB-3.html

I'm picking up the other cabinet later today.
These are made entirely from 3/4" solid Mahogany.

Was shooting for Cornscala D, but couldn't pass them up.

 

[tomlinmgt]

Nice. Is that a SEOS waveguide? What drivers are used?

 

[Mike Stehr]

Faital Pro LTH142 and HF140. Crites K33/CW1526.

 

[imral3]

WoW!! Very nice indeed!!

 

[nerdorama]

Mike, those are beautiful.
Enjoy,
John

 

[mashaffer]

Ooooo, Ahhhhh, Ohhhh!

 

[Stan man]

And how do they sound?
Very nice, BTW

 

[Mike Stehr]

Here's it's mate, still clad with Chinese orange grille covering...

 

[Mike Stehr]

So the supposed story is a guy in town back in the mid-late 50's, bought a 15" Tannoy Silver and had a local furniture maker build a Jensen BLH for the Tannoy.
Then stereo became popular. So the guy had another cabinet made, but couldn't afford another 15" Tannoy Silver.
So he bought an Altec 15" duplex of some model, can't recall the model the seller mentioned.

The guy that had them made must have not realized that the magnet/magnets of the Altec were too large to clear the doghouse.
And after the second cabinet was built he found out the hard way. So they chiseled clearance out of the sides of the doghouse for the driver to fit.

Wood bondo to the rescue...

 

[Mike Stehr]

It took some time to get these beasts sealed up to be listenable, but the work paid off...
A bit ugly at the moment without the trim and grille covering, but wanted to listen for a first take.

I'm rather impressed. I can easily live with these.

 

[Harvestor]

It took some time to get these beasts sealed up to be listenable, but the work paid off...
A bit ugly at the moment without the trim and grille covering, but wanted to listen for a first take.

I'm rather impressed. I can easily live with these.

What other speakers that you have had or do have are similar sounding to these ? Or are they completely unique ?..
Or better said comparable to?
Are they pleasant with certain genres more so than others? Like classical or pop rock?

 

[Drugolf]

Mike, where in E. WA you at?

 

[Mike Stehr]

What other speakers that you have had or do have are similar sounding to these ?

I had '89 LaScalas, but these sound a bit different than similar.
I have '82 Cornwalls, and while the Cornwall bass does extend a little lower, these have a horn like bass. It's kinda like both...Unique?

I favored the Cornwall, over the LaScala, and I like two-way over the Cornwall three-way to my ears. The cut-off is 500Hz.
Some slight boom, but no worse than Cornwall. I still need to experiment with padding the sides of the doghouse, to kept the back wave from reflecting through the cone.

These DIY Jensen speakers cabinets were made in the days of Jazz and Big Band prior to Jazz, so of course they can do that rather well.
Classical seemed fine, I didn't listen to much however. Jazz is real nice.
They play hip hop and pop rock with plenty of presence and strong bass.

Pine Top Perkins Ladies Man sounds really good. They passed the Die Antwood test.
Pop and Classic rock seems fine, dunno about heavy metal.

 

[Mike Stehr]

Mike, where in E. WA you at?

Cheney/EWU

 

[Mike Stehr]

The Jensen plans indicate dimension "A" at 36.5" tall for 15" drivers. Dimension "B" indicates 27" tall for 12" drivers.

The cabinets I have are 30" tall, with 15" drivers. Listening to them over time and running sine waves, I can hear some peaking weirdness that I'm guessing is too large a driver
in too small of a cabinet.

So I'm going to try using 12" drivers and hear how that works. I have pair of CDK coaxials to try, and numerous 12" woofers.

 

[Mike Stehr]

Using a CDK 12" driver (as a woofer) in one of the cabinets with the CW1526/K33 15" in the other cabinet, I swapped back and forth listening to FM music.
And then ran a signal generator on the side using the 12" driver.

Using the 15" woofers, there was a rather large peak at 300Hz that made them real boomy, with some lesser peaking at 100-180Hz.
While there still is some peaking at 100-180Hz using a 12" driver, I'm guessing that is room gain from a smallish room.

It seems I'm getting a little more lower bass response as well using a 12" with a higher Fs and a tight cone with very little movement.
85Hz must be the flare cut-off for this particular pair of horns. Both 12" and 15" woofers start rolling-off at 85Hz.

The CW1526/K33 would be pretty much flapping in the breeze by 50Hz. The CDK woofer will rattle the walls at 60Hz and vibrate the cabinet slowing down at 55Hz and then rolls-off by 45Hz.
(CDK woofer Fs is 45-50Hz.)

Nonetheless, the 300Hz peaking is gone using the 12". It seems to have less bass without the resonant peaking, but a more defined bass.
Dunno if the CDK is the optimum choice of driver for these cabinets. I have other 12" woofers to try, from floppy suspension compliance to tight and in-between.

One more baffle to go and I can listen to both cabs with 12" drivers...

 

[Mike Stehr]

Listening to both cabinets with the CDK coaxials, using their own tweeters and the stock crossovers.
http://www.amkspeaker.com/PDF/AMK XCX12A90.pdf

The tweeters have titanium diaphragms with a radial poplar wood horn.
There is a 4 ohm input resistor for the tweeter, a 5uF capacitor, with a .87mH inductor in parallel. The woofer is run wide open,(no inductor) with a Zobel network of 22uF and 6.8 ohms in parallel.

They sound good with the Faital Pro horns as a woofer cut-off at 500Hz as well.

Much better with 12" drivers in these cabinets...still should try other 12" woofers as well...

 

[Katalyst]

Much better with 12" drivers in these cabinets...still should try other 12" woofers as well...

What choices do you have? This will be interesting. The CDK coaxial alone looks period correct .

 

[Ray Ybarra]

Cool cabs. I like those coaxials in there.

 

[Mike Stehr]

Thanks!

What choices do you have? This will be interesting. The CDK coaxial alone looks period correct .

I have a pair Utah/Realistic "Americana" 12" coaxials. (or coax with whizzer cone)
The cone tweeters are mediocre at best, but I like the curvilinear woofer with the loose compliance and more travel.
They did rather well in a 3.5 foot cabinet sealed, with a bit of damping/polyfil If I remember right...

The only other pair I have to use would be a couple 12" Sansui W2000 woofers pilfered from Sansui SP2000 speakers.

I have more solo 12" woofers to try than pairs.
A 12" Knight KN-3000A, which looks like a green clone of a Electro-Voice SP12BW.

A Jensen W12NF "Flexair" 12" woofer. The cone/surround/dust cap look similar to the Knight KN-3000A. The basket/bell cap is brown and gold crinkle paint.
Finding a mate might be fun...

An 12" Alnico woofer pinched from a Conn organ, which I think it's a CTS P232. The Fs seems a little lower than the CDK woofer...worth a try...
A University 12" Diffusicone. Dunno about trying that one as the magnet is rather small.

I do like the looks of the CDK coaxial in the cabinets as well.