Chapman T7 Shorties

c-atle-79bay

c-atle-79bay

Super Member
IMG_1267.JPG I've finally managed to get my hands on a set of Chapman T7 speakers. These are the early versions, serial numbers 161/162 so truly early. The seller provided Kef B110's as the mid range as the original polydax were in need of being re-foamed. The manufacture indicated the B110's would be a suitable replacement. As well as replacement woofers. The one in the photo is a square back driver not certain of the manufacture. The tweeters are also Polydax and have a level adjustment that goes almost to off.

The only issue I'm having thus far is one of the tweeters is not working correctly. I've check continuity from the positive and negative terminals. The negative sounds it's connected, however the positive side only sounded as I turned the level adjustment (is that a potentiometer or rheostat is that has that feeling like turning an old thermostat) at a certain spot. I also connected the tweeter directly and it had sound, but I did only very low level. After hooking it up again, no matter how much I twist and turn it, nothing. I've sprayed it a couple times with Deoxit already and will try again, but after that will have to start investigating the cross over.

One question I have and seems obvious, continuity on the positive and negative sides are fully separated, if they are not, then that's a problem right?

Below are some early photos.
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I've done a bit more, with mixed results. One of the polydax hd100 d25 is blown and the kef b110's don't seem to mate well, the sound great but when pushed with anything bass heavy really seem to fall apart sound quality wise. So music with alot of deep bass, such as Daft Punk or really low string bass sounds out of sorts, like they are bottoming out.

The bass for a 10" sealed is very impressive, perhaps a bit boomy but I feel that is more my room, next time I have those out have to take a photo and confirm the brand, but was told they were direct replacements for the older eminence that came out. Fast rock or pop, say master of puppets or Michel Jackson hit hard and fast, almost relentless sounding with the hd100, so want to get the polydax replaced and work on a option for the mids.

Does anyone recognize that midrange? It's an aluminum frame, I can't get it ID'd by the codes I can find online.
 
Oh and another item, in place of the blown tweeter I disassembled my ESS heil Elites and tried the Heil, was 1/2" too tall and needs more current than is supplied to the audax to really shine. I suppose I could pad down the midrange and bass driver with resistors but feel like I'm getting too far away from the designed speaker at that point.
 
c-atle-79bay said:
Does anyone recognize that midrange? It's an aluminum frame, I can't get it ID'd by the codes I can find online.
Click to expand...

Hi, I spied those on Craigs too, nice catch..

The mids might be French made Polydax. Just my guess because of the basket. I bet Cy Beam would know.. You could call Stuart himself. Or email him he answered a question for me once. Nice man...
 
I can also check back in with the seller, he also knows his stuff too, just don't want to dip in the well too many times, same with Stuart, he's awesome and seems to love the hobby and to support his products.
mcgarick, didn't you have a set of custom chapmans a while back? Not sure where I saw them, might have been CL. Sorry to say when you brows CL too much you begin to recognize or think you recognize hobbyists.
 
Yeah, I had some late 70's model...let's just say time passed them by! I ended up parting them out. I think there's a pair of the same model for sale across the Tacoma bridge. I sell on Craigslist continually. I also buy too. I tried to be a fair and honest seller. And these days I don't sell any lame-o stuff because everything I have is pretty darn good hahaha seriously though I don't pick too many stinkers these days. I'm playing with a pair of wharfedale Dentons these are the 80th anniversary speakers so they are new. An Amazon acquisition. They're like harbeth in sound and or spendor. I'm really enjoying them ... they're breaking in now. If you're interested in hearing them you're welcome to come over and have a cup of coffee and listen to a couple of tunes if you'd like. I think they're going to be Keepers , I like them. Good luck with your new acquisitions and keep us posted on how they turn out. Inquiring-minds-want-to-know!
 
Those dentons sure look the part that's for sure. Yeah would like to hear them sometime. Not much action on the chapmans at this point. Contacted the seller, really cool guy, and has a set of the original mid range drivers that would have been in them.

For what ever reason, the kef b110's really sound rough, almost bottoming out when pushed to hard, they are not sealed, and can feel a bit of air leaking out, does seal vs mostly sealed have that much impact to the b110 performance?
 
I not an expert, but I would think either the woofer is interfering with the mid cone...or the x-over is a bit lowish of the mid...
 
I thought of a good analogy after posting this, and I think it relates to the mid not being sealed, it's as if it's farting when pushed hard. I know the b110's from another set of speakers and low range is not a problem for them. The mid cabinets are isolated from the low range drivers.

I'm going to try a couple different approaches tonight, I've got some foam gasket material that I'm going to make a temporary seal out of, not committed to silicon yet. And i'm going to take of the puffy insulation and use foam, like an LS3/5a would. If that does not work, the seller said he has some of the originals, but I'd like the KEF's to work out.
 
Could the driver be partly blown, and not handle power now? could be. Seal it up good and try. The dollar store up at Sunset (dollar tree?) has or had blue tack for a dollar a sheet. that could be good for a temp seal maybe....
 
Also, I wonder if the x-over itself is rattling when you crank it.....that hot glue does weaken over time when they glue to the particle board. seen that a bunch.......blue tac would be good to clobber that with too. just a thought.
 
Amazing what one little step can change. They are not perfect sealed if I push them in and out they will eventually suck in, but they are enough so that they are not blowing air out the seals and bottoming out.

Next step is to get some foam and line them like ls3/5a's and take out the batting. And I might put a layer of dynamat on the outside, since they are covered by socks I won't see it. It can't hurt I figure.

Crossovers are solidly attached still, but I did check per your advice

Thanks for your help mcgarck
 
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I went ahead and sealed the other speaker last night, so at this point i'm at 80% functionality, as I've got a not matching, much lesser quality tweeter in one. But all that being said, these are a nice speaker. I'm working on how best to describe them but sounds such as a cow bell or claves have a clarity that is striking. They are a hot speaker, but not fatiguing. At this point imaging is not stellar but I think that is due to 2 factors, the open back design along with the fact that my placement has both in corners along with the non-matching tweeters, but sounds harmonious. The bass for a 10" driver is very impressive, also combined with the placement which reinforces the bass a lot, particularly at my listening position. But songs like Brian Bromberg saga of harrison crabfeathers or Bela & Fleck Cosmic hippo the bass hits almost as low as my IMF TL Studios, it's not lacking is a better way to say it, and it's a 10" sealed design. Ok babbling now. More as I go forward.
 
Not sure how much this does, but the sound seems to have a bit more clarity. I have bunches of the stuff from a be bus sound deadening project. My bass has a bit of a boomy quality not that bad though was thinking of lining the back of the cabinet with some, you can feel a fair amount of vibration the down side is the speaker is covered in a sock so you'd see it if looking at it from behind. I can do the front with no visual impact though.
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I went ahead and lined the front and back of the cabinets with a single layer of dynamat. Not certain if I like the change or not, trade offs as always, bass was reduced a bit for say something like Metallica, but was tighter for Daft Punk (Gorgio is a favorite of mine). I think over all , it's a bit more controlled, and with my positioning, it helps more than it hurts.
 
If I change the impedance of the tweeter or just don't have one attached can or will it affect the crossover values of the other drivers? Or just that of the tweeter? I'm going to keep these stock, but an off chance I may run ess heil elites with them. If I do the elites then wonder if I need an 8 Ohm resistor in place of th stock tweeter in order for the rest of the drivers to function correctly.
 
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