Improving my Phy-Hp drivers - diyAudio
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Old 15th November 2007, 01:47 PM   #1
Sjef is offline Sjef  Netherlands
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Default Improving my Phy-Hp drivers

I am using some Phy-Hp LB21 8" widerange drivers for over 5 years in an open baffle by now and all this tme I have had a kind of love/hate relationship with them. They are very nice midunits wich do a lot of things very well but time tells that there are also some strong colourations in their sound. They can sound a bit like an old radio console from time to time. That's not that strange considering the fact that they are based on fullrange drivers from the 50's.

Anyways, I would like to see if there are some areas that can be improved to the divers themselves. This would be some kind of cone treatment, there's very little or none to be improved about their basket wich is allready very well executed.

so far I can come up with the following things:

Treating the cone with C37 laquer or maybe Ultee audio sound varnish

Adding a phaseplug to them to fill out the space between the magnet and the voicecoil.

The Phy-hp has no dustcap, it's some kind of transparant foam. If I would go with laquering the cone I guess I have to remove this foam anyway, otherwise it's not possible to treat the cone all the way down to the voice coil. What I understand about the C37 or Sound Varnish is that it stiffens the cone a bit. I think it wouldn't be a good idea to only treat the cone up until the dustcap foam and leave that last cm to the voicecoil untreated. Don't know if that will cause a strange transition from plain paper to treated paper at that point.

Doing something like the ENABL process tot the cones. I have tried to read a lot about the ENABL process but as far as I understand it up to this point is that there has to be a special pattern wich is specicfic to the driver to be treated. I would like to know more about it but it's difficult to read troug all the posts to come up with something practical usefull for me at this time. I also would like to know if this kind of treatment goes together with other cone treatments like the C37 or Sound Varnish.

All in all a lot of uncertainties because I don not like to screw up 1200 euro's on drivers offcoarse. That's always the trobe with expensive driver I know. Strangly it works that way psychologically. If I had a pair of viaston b200 for instance I would hesistate to treat them in certain ways because they are cheap enough to replace in case I screw them up. On the other side there's always the thought that the manufacturer allready tweaked a lot on these drivers, after all the Phy-Hp is kind of a tweaked version of the Supravox drivers.

I would like to know if anybody else has messed around with drivers like these and cone treatments, and offcoarse with what result.
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Old 15th November 2007, 02:20 PM   #2
Zen Mod is offline Zen Mod  Serbia
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if you directly ask BudP in EnABL thread - I'm sure that he'll answer you
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Old 15th November 2007, 03:32 PM   #3
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PHYs. You lucky, lucky...

I wouldn't be spending a fortune on C37. It has the weight of mythology to support. C37 has been extracted from the fangs of the Great Ooongabba snake by buddhist nymphets, mixed with fairy dust to the proportions of a secret Italian 300 year old violin-varnish recipie used by all the greats, and simmered slowly to perfection by Nigella Lawson.

Back on this planet, I don't think many people deny that it can have an effect (depends on what you're doing with it); the point is that something about 1/10 the price or less will probably do exactly the same thing. From some of the analysis made, C37 appears to be no more than a couple of relatively cheap varnishes mixed together with a copious amount of hype.

I'd probably start by adding phase-plugs (Dave's the man to ask about those), treating the cone with something like puzzlecoat, cut back 50% with water, and then go straight to EnABL. Yes, it needs subtly different patterns for each driver (naturally -as you rightly point out, you can't expect the same thing to work for every driver, given they are all different & thus need different applications), but Bud & Dave will be able to help with that. It shouldn't change the basic voicing of the driver, but it should help erradicate some of the less desirable features.
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Old 15th November 2007, 03:40 PM   #4
el`Ol is offline el`Ol  Germany
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A reversible experiment would be: Spray water on the cones, and if you like the result, take glycerol instead (has to be renewed once in a year).
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Old 15th November 2007, 03:46 PM   #5
tinitus is offline tinitus  Europe
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"Spray water on the cone" ... you cant be serious, it may deform the cone and ruin it completely ... I understand your theory, but please, dont do that
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Old 15th November 2007, 04:36 PM   #6
el`Ol is offline el`Ol  Germany
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I had the Ciare CH250 running "wet" with glycerol for a year and there is no deformation.
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Old 15th November 2007, 11:38 PM   #7
Sjef is offline Sjef  Netherlands
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The one thing I'm a bit afraid of is adding too much weight to the cone with some kind of coating. The Phy's are about the only wide range drivers I know that do not have a rising response. they measure almost flat up til 8 kHz. Adding weight might cause a falling response instead of a rising one. It could work the other way around though. By adding coating I might change the speed of sound trough the cone in wich case it might start having a rising response.

I know all the stories about the c37 coating from people who haven't tried it themself. I would rather like to hear some comment's from people who actually did try it. It's rather expensive yes, but I don't think it's completely BS.

One thing that a good coating might do to them I guess is that they become more resistant to humididty. I have noticed that these drivers start to sound more like old 50's console speakers when the air is more saturated with moisture. It's not that it's a very big problem though, I only started nticing after I have lived with them for quite a long time. Still I believe that some improvements can be made, just want to be carefull that's all
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Old 16th November 2007, 12:44 AM   #8
tinitus is offline tinitus  Europe
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Ideally you need a soft stiffening with say very thin shellack with a little bees propolis(very little), too much propolis and it will be too soft and too little and it will be too hard ... and MAYBE followed by a very thin coating of very thin bitumen, and I said maybe ... depends on how hard/soft your shellack/propolis mixture will be ... nahh, better leave out the bitumen stuff, its kind of ugly black stuff and not as aesthetical as the shellack/propolis solution
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Old 16th November 2007, 01:16 AM   #9
tinitus is offline tinitus  Europe
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BTW, its a spirit solution and dries quickly, sensible to moisture ... kind of organic

I have had very good results with polyurethane glue on the backside of cone, but I wouldnt try that on such expencive drivers
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Old 16th November 2007, 01:58 AM   #10
LilMik is offline LilMik  Germany
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Hi Sjef!

try a tweeter. you don't believe me? buy two piezos for about 10 bucks an give it a try. do not forget the x-over . yeahhh, it's not true fullrange anymore. but the phy is only a widerange driver anyway.

the 8 inch phy's does not have highs above 10khz. maybe that's why you think "They can sound a bit like an old radio console from time to time". i think you will be surprised how good the phy can sound if you hear it with a tweeter. i was. but i can not afford the phy .

have a nice day
mike
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