Pentagram speakers - What have I got here?

Roypercy

Super Member
Hey all:

Hoping somebody can give me some info. This morning on my way to work I responded to a CL "free" ad for a pair of "big, black, heavy 5-sided speakers on wheels". Thinking they just might be Khorns or something cool like that, I went. What I found are a pair of Pentagon speakers - the only identifying mark I could find so far is "Pentagram Speaker Corp" or something along those lines on ta paper label on the bottom. They're 3-way, black veneer over 1" MDF, very heavy internal wiring, pentagonal shape tapering up towars the top. About 3 1/2' to 4' high (sorry to be vague, they're in my car right now and I'm at work; I'll post pics later). These have not been treated well. A cat or seven went at the grille covers, the veneer has been rubbed thin in placesd, and the owner proudly showed me the woofers he refoamed himself - with foam rubber and white caulk, lots of it. The woofers might well need to be reconed or replaced. They have what appears to be a dome midrange and a ribbon tweeter. They are on casters, thank god, otherwise I might not have been able to get them to my car as they weigh probably 75 pounds apiece.

The bottoms of the speakers are open and there is no internal damping in place, don't know if that's intentional or if a bottom plate or something has been removed over the years.

Anybody know anything about these beasts? They look like they could be cool with some effort on my part. Thanks!
 
I bet if you play Black Sabbath on them backwards you hear exactly nothing just like regular speakers. :)
 
Mystery speakers - now with pics!

hey all:

I posted yesterday about this pair of freebies I got off Craigslist. All I know is what the label on the bottom says: Pentagram Loudspeaker Co". They are VERY heavy, 1" MDF with lots of crossbracing and heavy internal components.

It looks to me as if there used to be a passive radiator on the bottom (that open round hole on the bottom has screw holes in it) and internal damping; I can't imagine speakers like this not being a sealed design.

One of them has been knocked around quite a bit and has some things loose inside. I fired up the other one with a junk receiver and it sounded pretty good; the ribbon tweeter and plastic-domed mid were very smooth and clear. The woofer (not surprisingly) buzzed at moderate to high volume: check out that refoaming job the previous owner did!?!

Has anybody seen these before? Any ideas what they could be? The only clue I could find online was a brief reference to B&W hiring a firm called "Pentagram Design" to do a prototype of what would become one of their first classic speakers. Could this be it? Or some kind of cheap knockoff? Or Ozzie Osbourne's favorite speaker? (the dog in the photos is for scale...)
 

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They're the spawn of the debbil! Sacrifice them to a burn barrel during your next black mass.
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I think they're cool. Looks like quality construction, and probably decent drivers too.
Restore 'em and use 'em !!
 
Dude? WTF?

Sorry, man. Beelzebub made me do it.:smoke:

Stolen from another site:

"I have used a pair of second-generation Pentagram P10's as my main speakers for the past 26 years. They are excellent all-around performers, with no major weaknesses. They cost $1800 in 1983, iirc.

If the woofers on your speakers are truly 8 inches, they may be a smaller model which I believe they also produced, called the P8. My P10's have a 10 inch woofer, a 4 inch or so dome mid-range, and a one-inch or so ribbon tweeter (it was claimed to be a ribbon, but I don't recall if it really was one, the alternative possibility being an etched voicecoil leaf tweeter). It also has a 15 inch mechanically tuned passive radiator on the bottom. "Mechanically tuned" means in this case a large rubber band-like thing attached between the center of the cone and a wooden cross-member within the speaker, which holds the cone under a certain amount of tension.

There was an early version and a late version of the P10. They can be distinguished by the fact that the early version had a smaller dome mid-range (around 2 inches, instead of 4), and a mica top. My later version has the 4 inch or so mid-range, and a painted wood top.

Mine is finished in a beautiful light oak veneer.

Specs are as follows:

Power handling 35W minimum, 200W continuous
Sensitivity 90db (1W, 1meter)
Frequency response 24 to 20000 Hz +/- 2db
Impedance 7.2 ohms nominal, 5.7 ohms min

The truncated pyramid design serves two purposes: It time-aligns the drivers with each other, and results in there being no parallel surfaces internally, which eliminates the need for internal damping.

They are a fairly easy speaker to drive, and I've had excellent results with both tube and solid state amplifiers. Their bass is deep, loud (when it should be), and tight. The rest of the spectrum is very well balanced and integrated. Imaging is very good, especially with tube amps. There are no particular colorations in any part of the spectrum, and I consider their weaknesses to be subtractive, i.e., a lack of the kind of detailing that good planar speakers can provide.

I recently had the surrounds redone on the woofers and passive radiators by Bill LeGall of Millersound.net (not .com), who did a wonderful job. They were not rotted or disintegrated, just torn, I suspect due to a combination of age-related loss of flexibility coupled with being driven hard.

The company only existed for around 3 years or so in the early to mid-1980's. Its president was a youngish fellow named Michael Levy, who was the designer, and the speakers were assembled in the garage or basement of his house in Queens, NYC. The cabinet was custom-made to his specs by an outside cabinet-maker, and the drivers were from well-regarded companies such as Seas.

Hope you can get them restored to good shape -- they are excellent performers, especially if they are P10's in the later version, and I feel that you would have to spend perhaps $5K or more to duplicate their combination of bass performance, dynamic range, and overall balance and accuracy with today's speakers.

Regards,
-- Al"
 
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Sorry, man. Beelzebub made me do it.:smoke:

Stolen from another site:

"I have used a pair of second-generation Pentagram P10's as my main speakers for the past 26 years. They are excellent all-around performers, with no major weaknesses. They cost $1800 in 1983, iirc.

If the woofers on your speakers are truly 8 inches, they may be a smaller model which I believe they also produced, called the P8. My P10's have a 10 inch woofer, a 4 inch or so dome mid-range, and a one-inch or so ribbon tweeter (it was claimed to be a ribbon, but I don't recall if it really was one, the alternative possibility being an etched voicecoil leaf tweeter). It also has a 15 inch mechanically tuned passive radiator on the bottom. "Mechanically tuned" means in this case a large rubber band-like thing attached between the center of the cone and a wooden cross-member within the speaker, which holds the cone under a certain amount of tension.

There was an early version and a late version of the P10. They can be distinguished by the fact that the early version had a smaller dome mid-range (around 2 inches, instead of 4), and a mica top. My later version has the 4 inch or so mid-range, and a painted wood top.

Mine is finished in a beautiful light oak veneer.

Specs are as follows:

Power handling 35W minimum, 200W continuous
Sensitivity 90db (1W, 1meter)
Frequency response 24 to 20000 Hz +/- 2db
Impedance 7.2 ohms nominal, 5.7 ohms min

The truncated pyramid design serves two purposes: It time-aligns the drivers with each other, and results in there being no parallel surfaces internally, which eliminates the need for internal damping.

They are a fairly easy speaker to drive, and I've had excellent results with both tube and solid state amplifiers. Their bass is deep, loud (when it should be), and tight. The rest of the spectrum is very well balanced and integrated. Imaging is very good, especially with tube amps. There are no particular colorations in any part of the spectrum, and I consider their weaknesses to be subtractive, i.e., a lack of the kind of detailing that good planar speakers can provide.

I recently had the surrounds redone on the woofers and passive radiators by Bill LeGall of Millersound.net (not .com), who did a wonderful job. They were not rotted or disintegrated, just torn, I suspect due to a combination of age-related loss of flexibility coupled with being driven hard.

The company only existed for around 3 years or so in the early to mid-1980's. Its president was a youngish fellow named Michael Levy, who was the designer, and the speakers were assembled in the garage or basement of his house in Queens, NYC. The cabinet was custom-made to his specs by an outside cabinet-maker, and the drivers were from well-regarded companies such as Seas.

Hope you can get them restored to good shape -- they are excellent performers, especially if they are P10's in the later version, and I feel that you would have to spend perhaps $5K or more to duplicate their combination of bass performance, dynamic range, and overall balance and accuracy with today's speakers.

Regards,
-- Al"

Great info, man, thanks!

Now the question is: where could I get a passive radiator or how do I cock up some kind of acceptable replacement? Wonder if this Michael Levy is still around?
 
I got a pair of these also. I bought mine with a blown mid range, it took me about 6 months to purchase the new midrange, but have yet to install it.

If you find any further info on these, PM me. Also if you need detailed pic's, and measurements of the stand, let me know.
 
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I got a pair of these also.

I bought mine with a blown mid range, it took me about 6 months to purchase the new midrange, but but have yet to install it.

Have any pics of yours by chance? I'd love to see what these look like when they haven't ben abused...

Where did you find the midrange? Did you find an exact replacement, or an equivalent?

Roy
 
Pics posted up above: I posted a similar thread awhile back, and a few people thought they were bang&olsen, others dis-agreed.
 
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I found what seems to be an exact midrange driver replacement on the E Auction site.

Bang&Olsen uses the same driver in some of there speakers. There is a plastic surround, that requires some fabrication, in order for the driver to fit within these mystery speakers.

It's not a major fabrication, nothing that a dremmel, and 15 minutes of time couldn't handle.
 
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