Are you (open) baffled yet?

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Vibrating of the baffle isn't always a bad thing. If you can keep it under control it can also help the performance of the driver. Audio Note for instance uses this principle for years in their speakers and I can't say that they are bad sounding. Also mr. Salabert, the founder of Phy-HP has experimented a lot with controlled resonances of enclosures for his speakers.
Regarding the value of resonating baffles I would like to go back in time - to my first OB test. The driver (Fostex FF85K) was mounted on a single baffle (1m x 1,20m particle board) and especially solo cello music was sounding magnificent - because the whole baffle was resonating beautifully with the instrument. There was more "body" than the little Fostex could have produced by itself. Large orchestral music on the contrary sounded mushy, because the big resonating baffle area blurred the imaging of instruments.

Making the baffle resonance part of the musical reproduction certainly is an interesting option, but I for myself have decided to go for less resonant baffles and make the speaker the only soundproducing element.

Erik wrote:
PHY-HP publishes recommended plan for a large folding baffle. The plan specifies the use of (difficult to find and expensive) piano hinges. This is to seal the folds.
My actual baffle wings are with piano hinges. I´ve done a picture of it, showing the gaps in the hinge, that don´t seal much. I have even taped the hinge with duct tape, but couldn´t hear any difference.

In a previous attempt of isolating the wings I used hooks and eyes with a rubberprofile in between (see second picture). This was rather efficient in terms of isolating, but mechanically rather feeble.
 

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diyAudio Editor
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My personal opinion is that I want a well-damped baffle, and one ridgid also. Just trying to stay open minded. The cello vs. orquestra example seems to make a lot of sense to me. A resonant baffle is going to sound better on some things than others. Now, if you could tune it to correspond to a dip in the driver response- maybe.

Frank , I may be wrong, too lazy to check, but I don't remember a damped mounting to the baffle mentioned, BUT what interested me was the idea of having the driver rigidly mounted on a stand but not touching the baffle, or rigidly mounted on a stand and having resiliant gasket at the baffle. So the driver is firmly mounted and it isn't linked to the baffle , thus producing less resonant coloration in the baffle.

Hey, remember when you and I defended Supravox as not being necessarily totally defective? ;) Maybe we were on the right side in that one!
 
diyAudio Senior Member
Joined 2002
Hi,

Hello Marc,

BUT what interested me was the idea of having the driver rigidly mounted on a stand but not touching the baffle, or rigidly mounted on a stand and having resiliant gasket at the baffle. So the driver is firmly mounted and it isn't linked to the baffle , thus producing less resonant coloration in the baffle.

Now that could be a very good idea.
Well executed it would make the baffle much less prone to self-excitation.

Frank , I may be wrong, too lazy to check, but I don't remember a damped mounting to the baffle mentioned,

I didn't say it was you mentioning it...don't think it was.
Probably someone else prior to your post.

Hey, remember when you and I defended Supravox as not being necessarily totally defective? Maybe we were on the right side in that one!

Yeah...how could I ever forget...
With the Fertin being so expensive AND hard to come by I feel the Supravox is an excellent alternative.

Oh, BTW, the plan of the open baffle is on the PHY-HP site, not the Supravoxs' as I wrongly put it.

I hear feedback from people having listened to the PHY range that was rather underwelming.
Has anyone else experience with these speakers?

Cheers and greetings,;)
 
fdegrove said:
I hear feedback from people having listened to the PHY range that was rather underwelming.
Has anyone else experience with these speakers?

I can understand the underwelming reactions to the Phy's. I really don't understand that people can listen to them without a tweeter. They stop radically at 9 kHz, output at 20kHz is allready about 35 db down. Also the Phy isn't very fast in the higher frequency and has got some nasty colouration up there. That's why I use them only till 5 or 6 kHz. Yes filtered fullrange, I know that's against the single driver relegion, but I don't care as long as it sounds good to me.

I've tried a lot of different tweeters and ended up with a Cabasse DOM20 dome tweeter. There where better tweeters but they didn't integrate as well as the Cabasse does.

Also the Phy can sound really bad with transistor amps, you really should use a good SET amp with them otherwise it's gonna be disapointing.

No speaker is perfect but the Phy has the lovely live and dynamic midrange I happen to like.

I would like to hear more from people who have tried "resonating" baffles. I'm still considering. The comment on the blur with big orchestral works was some of the things I didn't like about the Phy enclosures with 4mm walls.

I was hoping that the sitca spruce would have better acoustic properties so that the baffle wouldn't blur as much as a thin multiplex baffle.
 
diyAudio Senior Member
Joined 2002
Hi,

Also the Phy can sound really bad with transistor amps, you really should use a good SET amp with them otherwise it's gonna be disapointing.

This I find very worrysome.
Shouldn't a good speaker sound good with good electronics regardless whether sand or hollow state?

Granted, with high effeciency as this a good SET amp seems to me the way to go but still.

Cheers,;)
 
No it's not that worrysome. I also know of a lot speakers that don't sound any good with SET amps as well. A transistor amp just tries to keep the PHY too much under control and they don't like that. That also counts for the Supravox, Fertin or Lowther drivers, actually for almost all drivers with a very stiff suround.

I've got a pair of LS3/5A monitors wich can sound very sweet on the transistor amp but sound like crap on the SET amp.
 
frugal-phile™
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fdegrove said:
I hear feedback from people having listened to the PHY range that was rather underwelming.

I've heard the 12 with the tweeter & the 8. Even giving room for the venue, i was underwhelmed.... the 8 seems to have some real potential, but the factory specified box does not come close to exploiting its potential.

dave
 

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Re: Re: Glass baffles?

Variac said:
Tcpip
Use the glass. At that price you can't go wrong, and I suspect they wil be bette, not worse.
Kuei Yang Wang said:
From my general experiences using glass as acoustic and/or structural material, excellent sounding and very breakable.
Thanks, all.

I have a "spare" sheet of glass, about six feet by five, which I can get cut at the cutters as per my specs. I am thinking of building a baffle with wings. The central piece will be of thick ply, with a 4mm veneer front. This veneer helps me get the flush mounted finish for my drivers, since I mount the drivers on the raw ply/MDF, and then cut the veneer so that the driver sits "inside" the veneer. And I'm thinking of using glass for the wings. Will keep you posted once thiings are ready. Am at the prototype buildig stage, when glass will not be used (for obvious reasons).

Tarun
 
(off-topic) SET amps sound different

Sjef said:
No it's not that worrysome. I also know of a lot speakers that don't sound any good with SET amps as well. A transistor amp just tries to keep the PHY too much under control and they don't like that. That also counts for the Supravox, Fertin or Lowther drivers, actually for almost all drivers with a very stiff suround.
From whatever I've read, it appears that valve amps have high output impedance. Maybe this makes them electrically very different when interacting with the speakers? Maybe some speakers sound better with a source impedance comparable to their own impedance, some need the exact opposite? I can't imagine a speaker with passive XO which will sound the same irrespective such large changes in source impedance. Their XO behaviour will get totally messed up. I believe Lynn Olson's Ariel is "tuned" for the high source impedance which comes from valve amps.

And when you're doing single-driver, I guess the non-linearities of the driver's electrical characteristics will react differently to the amp's impedance, even though there's no XO.

Tell me if I'm totally wrong... I know next to nothing about valve amps anyway.

Tarun
 
Sejf wrote:
I can understand the underwelming reactions to the Phy's. I really don't understand that people can listen to them without a tweeter. They stop radically at 9 kHz, output at 20kHz is allready about 35 db down.

I agree completely. The (non-coax) PHY's are wide-range drivers, not true fullrangers. Without help on the top end, they sound rather lifeless.

It has also been my experience that they can be sensitive to amplification. When I hook mine up to my Parasound HT amp, they lose all their glory. They are nominal 16 ohm drivers, so its reasonable to assume they were designed for (and tuned with) tube amps.

In general, the PHYs are underwhelming. I believe they are designed that way. One of the qualities I enjoy with the PHY is that the sound is completely non-fatiguing. You can listen for hours and hours. At first blush they seem to not provide the same detail as some other drivers, but when you compare, nothing is missing. For me, its like SACD vs CD. Detail is there, but with a softer edge and a natural presentation. It's a matter of personal preferance.

The idea of thin walled resonating cabinets is very cool, but one I intentionally avoided when designing my speakers. To do this right, you need to have depth of understanding ot tonewoods, glues, varnishes, resonance chambers and bracing, not to mention an accurate measuring system and a lot of time and money for prototyping. Too many variables for me. I have an ongoing project crafting a solid-body strat clone, but I wouldn't dream of trying to build a Martin acoustic.

Sejf also wrote:
I use them only till 5 or 6 kHz. Yes filtered fullrange, I know that's against the single driver relegion, but I don't care as long as it sounds good to me.

I'd be interested in the details of how and where you crossed them. I've been slowly coming to the same conclusion.

Regarding designs with a rigid frame and a free-floating baffle, has anyone seen this link?

http://www.decdun.fsnet.co.uk/project.speakers2.html#baffle
 
You are absolutely wright about that Erik. Building a vibrating baffle is like building an acoustic instrument. That's why I didn't give this project a go yet. I know that Audio Note has spent years in developing their woodworks. Although they look very simple they are not that simple at all.

Yesterday I have got a gift from a friend. He gave me a very large piece of plexiglass (1*2m) of 15mm thick. So I think I'm going to try the plexiglass baffles first. Any good advise on sawing and polishing this stuff ??

About the filtering. I'm still working on that one to. At this moment I'm filtering the Phy with a coil of 1,5mH with a resistor of 18 Ohm across it. That gives the Phy a rollof at about 6 kHz with a slope of a little less than 6dB/oct. The Cabasse tweeter is crossed with a cap of 3,3uF and an inductor of 0,22mH. That gives the tweeter an acoustic response of 18dB/oct at 6 kHz. The tweeter is damped a little with a L-pad. This crossover isn't perfect yet. I'm going to do some other experimenting soon. Uptill now it sound better in my ears than the Phy full range, I think it has to do with the fact that the Phy (and many other 20 cm full rangers) sarts to beam to much above that frequency.

The Phy can sound wunderfull at full range with some kinds of music but I want a speaker that sound good on everything you play with it. Like every (and I mean EVERY !!!) speaker it's a matter of the right compromises. There simply doesn't exist a speaker without compromises.

p.s. before people start to think that the Phy isn't a good speaker. I have had the same kind of experience with the Supravox, the Phillips AD9700 and the Fostex FE208 sigma. Tried them all and the Phy was the best sounding so far.
Also had a lot of "conventional""High End" speakers and like the Phy a lot more. The supravox has more or less the same character (why am I not surprised) but it's not that refined. It's that 20% extra for wich you pay a lot more, as allways with Hifi gear. If you want to spent (a lot) less money go for the Supravox.

Erik, How does the ESg ribbon match with the Phy ? . I like ribbons a lot but I know that it's hard to find a good partner for them because they are so damn fast. Would like to try it though.
 
frugal-phile™
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From the other end of the spectrum

I needed some outdoor speakers on the WE, so i refurbished a set of old Stromberg Carlson portable PA enclosures with some 12" FRs i had kicking around... not the be all & end all, but you can listen to them & enjoy...

dave
 

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Circular baffles would in general be undesireable due to the sharp cancellations that occur as the baffle radius equals the sound's wavelength (or is it half wavelength?), as well as multiples thereof. This will produce sever comb-filter like notches in the frequency response.

With a rectangular baffle, there is not a fixed baffle radius, so each vector from the speaker center to baffle edge will have it's own characteristic set of frequency response notches. The net result is that the continuously varying notch spacing will greatly smooth out the response.
 
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