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MF 1000

Modified Cambridge R50 Transmission Line Speakers

70 posts in this topic

The veneer was from IPL Acoustics.... its walnut and a good price from Ivan. There are joints on either side ...but gaps are filled in with Libron Dark Walnut wax filler

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The veneer was from IPL Acoustics.... its walnut and a good price from Ivan. There are joints on either side ...but gaps are filled in with Libron Dark Walnut wax filler

Ivan flies a little bit under the radar for most hifiers, but he has some good product at good prices, IMO.

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What next....well a move to better quality caps...maybe some Mundorf M caps and some nice Mundorf M Foil air cored inductors.

Keith

Just ordered a new pair of inductor coils and caps

c-coil-450.jpg

Janzen torroidal inductor using 2 mm thick copper

silver-cap-600.jpg

and Janzen silver foil caps. They should be with me in two weeks ....ill keep you updated with the progress

Keith

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What next....well a move to better quality caps...maybe some Mundorf M caps and some nice Mundorf M Foil air cored inductors.

Keith

Just ordered a new pair of inductor coils and caps

c-coil-450.jpg

Janzen torroidal inductor using 2 mm thick copper

silver-cap-600.jpg

Keith....

Have you made ay progress on the copper leaf for the B139?

I'm very interested to find out how it is done.

Peter

and Janzen silver foil caps. They should be with me in two weeks ....ill keep you updated with the progress

Keith

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Ive not made any progress yet on the copper foiling.....mainly due to the tweaking off the crossovers and currently experimenting with bi-amping them too. I will eventually get round to trying out copper foiling both the outer chassis ring of the racetrack 139's and the flat face of the driver.

Of course any progress I make will be documented and reported on this thread

Keith

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At last the Jantzen torroidal coils and silver caps have arrived :D

Straight out of the box and get them ready to fit on my test cross over boards. First impression as I unpacked them...wow they are huge... the torriodal coils are a Jantzen C-coil 3.90mH 0.6 ohmn wire gauge 2.00 mm and weigh 2lbs (900g) each. These are a simple 1st Order filter for the transmission line bass to start to roll off around at 160 Hz. The silver caps act as a high pass filter abover 2900 Hz for my twin Kef tweeters housed above the Fostex full range drivers.

I quickly fitted them onto my basic test board made for the previous monacor/maplin crossover test along with the equally large silver capacitors u

oveallx-over.jpg

here is a couple of pics to show the size of the components....

Jantzensilvercap.jpg

torriodcoil1.jpg

...and 30mm high

I know they will require some burning in ....but the intial listening had me smiling ...more detail in the bass and a crisper top end. I hope this is only the start and they reveal even more as they settle in.

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Those look decidedly Proper :^

I love the look of the torriods...pity you cant remove the shrink foil round them (Jantzen said the coills could relax changing the inductance value) ...would love to have them mounted ontop of a perspex cyliinder - would look lkie a mini Van Den Graaf generator ;)

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Finally getting started on the copper leaf 'guilding' of the B139 bass drivers. I found a seller on eBay who has 0.15mm thick self adhesive copper sheet - think of thick baking foil. I got a 1m x 300mm length for £10 inc postage to try out.

As im also restoring my IMF TLS 80 speakers so after just finishing repainting the baffle I thought id try the foil out on the B139 driver on this speaker first.

The self adhesive is very sticky ....and once the foil is creased...thats it forever :( - so my 1st attempt wasnt good .... but then found if you apply the foil from one end and use the edge of a bank card to smooth the foil and push away the backing paper as you go as good finish can be acheived as you can see in the pics below. The foil is easily trimmed with a scalpel...so I just ran it over the edge then trimmed it back to the edge of the front face of the B139.

photo3.jpg

photo-2.jpg

A break for lunch now and then move on to the R50 TL - more pics etc later

Keith

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Ive spent most of the afternoon applying the copper foil to the front facing drivers on my transmission lines. As I said in my earlier post the trick to getting the foil wrinle free on the surface is using a bank card or similar piece of plastic to push the foil off the backing paper onto the surface

photo4.jpg

moving further down the speaker smoothing as I go

photo3-1.jpg

after smoothing out and trimming the edges with a scalpel folding them over

photo2-1.jpg

here is the finished speaker overall

photo1.jpg

and the two speakers in place

photo5.jpg

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Lovely job, blingtastic, really liking that effect:D

Once I get some more foil i'll be covering the mounting ring of the B139's too

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Yesterday afternoon I thought id make some revised mounts for the torrid inductor and jantzen silver foil capacitor that act as 1st order filters for the R50 TL bass and KEF tweeters. I thought id keep it as simple as possible with a view to refining it at a later date.

DSCF2560.jpg

I quite like the 'starkness' of it plus it shows off the torroidal inductor

I aslo did a bit more with the router on the tweeter housing

DSCF2562.jpg

almost ready for the veneer now :)

Keith

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Did you build the imf type speakers yourself and are they oak veneered, look nice, would look even nicer in my living room me thinks!:22:

They are copies of a Cambridge R50 that I made....but with an extra B139 bass driver in the rear baffle - thought the bass on my IMF TLS 80's was good till I made these !! They are veneered in dark walnut. If you want them in your lounge ..... well you can carry them down my stairs - each bass unit weighs in at over 130lbs !!

They probably cost me around £300 to build with a further £80 for the isolation feet and the torroidal inductors at £30 each

If you ever want to listen to them...pm me

Keith

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