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In Reply to: My exp. w 8" Isophon posted by Elmo on April 6, 2007 at 21:20:11:
Elmo,
very good to know someone using the isophons. Mine are the PSL 245/35, there is a catalog floating on the net, in fact, here is the URL http://www.lup-berlin.de/archiv/Katalog/index.html . Mine are in the 1969 Catalog, but I think they were produced at different times. Maybe you can find yours there, they have many catalogues.From the graph there mine should go flat to 7k and then fall smoothly.
What tweeters did you finally choose?
Right now hearing them on OB. It is daytime here and now I can krank up the volume, very very nice! Lots of LF response. If I didnt have the JBL 15" I could live with them alone.
Follow Ups:
Peeked at a couple of Isophon catalogs on the net, the range is truly quite expansive. Mine are half roll, cloth surround (haven't tried pleated/accordion). And .... stickered Blaupunkt (also seen some labelled Echolette as well). After two years, finally tried some small four or five inch wings, which was a noticeable plus (baffle size 24" x 29"). Carboard no less (will get around to something a little more eye pleasing when convenient).Tweets .... vintage 60's/70's mass-fi pulls [land of the rising sun (woofs same)]. Started with small, coax mounted (flown by wire) dipole cones (wired out of phase). Then ... some semi-vintage ceramic bullet horns. My two current drivers are really quite tasty. Don't know that I'll bother detouring through regular vint American iron, before giving fieldcoil an eval (sometime down the road). First though, will be a return cross check using birch ply (new baffles are butcher block), and perhaps mounting the twelve higher up/closer to top.
So it seems you are using the 12" with woofers below. Are your woofers OB as well?One thing I would like to ask is if you noticed a clearer more refined midrange with the 8" as with the 12". If you settled on the bigger drivers it is obvious you found them better. Would you mind telling me how they compare?
If you are building new baffles I might suggest doing a sandwich-composite construction. I have not measured, but I am suspicious that baffles have a not unsignificant output on their own, i.e. they resonate. I will also build proper baffles later on, I am going with two thin layers ply with a sort of cheap, heavy asphalt isolator (for roofs, I think) in between.
Another -more complicated- option is to decouple the driver (mid/woof) from the baffle. One would have to build an external support for the driver. The advantage would be: a much lower intensity resonating baffle, and probably a much stiffer mount for the driver (will not swing back and forth): more microdetail. At the circumference of the baffle there would have to be a rubber "gasket" (which I would mount from the drivers circumference to the sufrace of the baffle). That would avoid cancellation losses due to the small opening between baffle and driver.
best regards.
the Isophon 8"s are now officially retired. The biggest, most noticeable change was on massed vocals. Still, that took me a day or two to figure/quantify/get a handle on. Once I became aware that the twelves were better in at least one facet, I was then able to listen for other areas. Over the whole week I realized that simply because they played with less dynamic constraint/compression, that they simply were better. Unfettered, unrestrained. Even in the mids. But possibly some of that that benefit comes from a near magical blend with the tweet (crossing over lower than with the 8"). But in my estimation there is no suffering in the mids because of the larger driver.There is no internal dialogue that they are slower, or less transparent, blah, blah. But yes, I believe the larger heavier cone imparts an ever so tiny darker personality (which has faded from notice). But the music breathes, the notes are free. This cardboard condo resident did however have to come to grips with the new, healthier LF balance. But over the week, came to accept that it's on the record/is in the studio, and ..... is the way the music actually sounds :-)
As far as baffle construction, I have become quite/rather single minded about the whole affair. Accepting (even welcoming) the panel's ouput as part of the total musical soundfield. Having glued some braces on my last birch panel pair [with 8"s (for all the usual auidofool reasons)]. I discovered that the enjoyment of music had completely vanished [merely with the addition of a single glued in place brace (which was quickly remedied with a hammer)]. I see the panel as part of a two piece sytem, together with the driver.
Placing a finger on my baffles during playback, reveals not really that much energy present. And ergo, damping became the greater evil. The little spot of life induced by the driver into the baffle, supported the enjoyment of music. Killing it, killed all of the beauty and charm. I would caution against against dead, or complex without first giving a listen for an extended period of time to either plain unadorned 3/4" birch ply, or butcher block. I don't as yet have a handle on the butcher block, but it doesn't seem to be any sort of handicap. And .... many notables have expressed a strong/decided preference for it. I never engage in one way tweaking. But now that I feel more than comfy with the twelves, the resident birch baffles for the 8's, can now be cut for the twelves. As always, never a hurry .... is it noon yet?
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