The Beryllium Myth

[Ian Mackenzie]

I started this thread by pulling posts from a thread where this Be conversation was going off topic.

Widget



Good to see this thread is still alive.


I must say..I prefer beryliium..with a momentary lapse of reason "even in the quietest moments"

iMac

[Ian Mackenzie]

The motive here is that spurious noise or resonances (from drivers) and distortion from equipment make people want to Eq or treat their room. :dont-know

The Be drivers are remarkably quiet. It helps if you can isolate what the problems are. Then dealing with them is much easier.

[Ian Mackenzie]

Ian,

Be is best ! anything else is a fools overture



Rich

I think that is a bit strong.

Besides, be is a rare metal..there might not be enough to go around!

[KCCT82]

The Be drivers are remarkably quiet. It helps if you can isolate what the problems are. Then dealing with them is much easier.

Don't know if the problems are from Be or not drivers (no knowledge in this area), but my TAD 2002 driver on TAD 2002 horn was much quieter than my BMS coaxial driver on TAD 4001 horn. Everything else in the setup stayed the same. Next would be to try the 2452H-SLs

Besides, be is a rare metal..there might not be enough to go around!

Might be one reason why they have the Be/Al alloy, another one more obvious being the cost... Anyone got a chance to hear these kind of diaphragms/domes?

[Mr. Widget]

...but my TAD 2002 driver on TAD 2002 horn was much quieter than my BMS coaxial driver...

Quieter? Please explain.

Might be one reason why they have the Be/Al alloy, another one more obvious being the cost... Anyone got a chance to hear these kind of diaphragms/domes?

Who is making Be/Al alloy drivers?


Widget

[KCCT82]

Quieter? Please explain.

At the listening position I could hear noise coming from the BMS drivers, thought they were from ground loops or cables being too close When I switched to TAD 2002 Be drivers, noise reduced to only being audible when I stick my head in front of the horn. Nothing was different except for the drivers/horns and the extra extra long banana plugs provided by TAD. Definitely quieter background when listening to music. These are just subjective listening impressions, the "quieter background when listening to music" might just be perceived to be so because of the extra detail I got from the Be drivers. (Be careful buying used 2002s, they need those extra long banana plugs, regular ones don't plug in deep enough into the driver. No binding posts either, you WILL be stuck w/o them!)

Another thing to note is that although there was noise from the BMS, it reduced a bit when I switched from BMS fiberglass horns (2236) to TAD 4001 wood horns. I don't know how that's possible, but I heard the difference. Again, no measurement to support, but I did use the same BMS horns for 3 years before switching to 4001 horns.

Who is making Be/Al alloy drivers?

Well... I dont know if anyone IS making drivers, but there is a Be/Al alloy for audio use. I was hoping someone else could tell me if there are ready made products using Be/Al

Some info here:

http://www.berylliumproducts.com/Acoustics.aspx

[KCCT82]

Hmm... quick google search... KRK studio monitors use them

"Reproducing the top end is an all-new, 1-inch, inverted-dome AlBeMET tweeter. AlBeMET is a composite material comprising aluminum and beryllium, which offer extremely flat HF characteristics all the way out to 30 kHz within ±1 dB."

http://mixonline.com/gear/reviews/audio_krk_expos_eb/

Umm... moderator? should we move this to another thread? Thx

[Ian Mackenzie]

KCCT82,

Any one who owns Tads or JBL Be drivers know exactly what you are saying. If they dont they probably have hearing damage.

[KCCT82]

Any one who owns Tads or JBL Be drivers know exactly what you are saying. If they dont they probably have hearing damage.

Right... and anyone who had done room treatments would know exactly what you are saying too. If they dont they too probably have hearing damage. Widget asked, I answered. I apologize for going off topic, but like I said in the earlier post, moderators can move it if they feel the need to.

[Mr. Widget]

KCCT82,

Any one who owns Tads or JBL Be drivers know exactly what you are saying. If they dont they probably have hearing damage.

I own TADs and have heard quite a few JBL Be drivers and I haven't a clue as to what you are talking about. I had my hearing checked about a year ago and I was still able to hear quite well... the doctor was surprised how well.

Are you saying that you think that Be is inherently quieter?

Lower distortion, sure, better damped, sure, higher resonance and break up, you bet, but quieter?


Widget

[Mr. Widget]

At the listening position I could hear noise coming from the BMS drivers, thought they were from ground loops or cables being too close When I switched to TAD 2002 Be drivers, noise reduced to only being audible when I stick my head in front of the horn.

Not knowing all the facts here, I'd speculate that this is due to a resonance peak in the BMS that is not present in the TAD. This peak will play system noise (or musical content) at a higher SPL level... think narrow band EQ up top with 10db of gain. Changing horns could also affect this as one horn may roll off more than another in it's on axis response.


Widget

[KCCT82]

Not knowing all the facts here, I'd speculate that this is due to a resonance peak in the BMS that is not present in the TAD. This peak will play system noise (or musical content) at a higher SPL level... think narrow band EQ up top with 10db of gain.

Mr. Widget- that sounds convincing... is there a ball park answer to what freq. polyester diaphragms break up at? Is there a way of telling where it's at from the response curves? Thx

[Ian Mackenzie]

I own TADs and have heard quite a few JBL Be drivers and I haven't a clue as to what you are talking about. I had my hearing checked about a year ago and I was still able to hear quite well... the doctor was surprised how well.

Are you saying that you think that Be is inherently quieter?

Lower distortion, sure, better damped, sure, higher resonance and break up, you bet, but quieter?


Widget

Have you heard of Cone Cry?

Probably not. Its Loudspeaker talk.

A term driver engineers use to describe the behaviour of rigid cone drivers, notably kelvar when they are pushed at high output levels.

I know you are not technical but every driver known to Man makes a noise other than produced by the signal put into it. Some more than others.

Therefore if you subtract the output produced by the input signal you are left with the noise of the diaphragm from self induced vibrations during the signal and after the signal stops.

Some people woud say, ah but that is distortion. Well some of it probably is from the flux modulation and other things. But if you account for that what you you left with? Something's making a bloody lot of noise. There are various reasons for that. I dont want to go there now because I dont have all day to explain it.

As an analogy if you jump in a car and play a cd you will hear the Cd and depending on the car a lot of road noise from the types and the body of the car. Some tyres and car body's are alot quieter than others by the way.

Its a just term I and a number of others use to distinguish between Be drivers and the behaviour of other types of drivers.

[Mr. Widget]

Have you heard of Cone Cry?

Ok, Mr. Technical, I think your "technical" term cone cry is refering to:

Lower distortion, sure, better damped, sure, higher resonance and break up, you bet, but quieter?

Good grief.


Widget

[Mr. Widget]

Mr. Widget- that sounds convincing... is there a ball park answer to what freq. polyester diaphragms break up at? Is there a way of telling where it's at from the response curves? Thx

I have no experience with polyester diaphragms, however being that they are not as rigid per gram as AL or Be, I'd assume that their mass break point is lower in frequency (for a given diaphragm size). Take a look at this document from JBL. It covers the subject really nicely.

http://www.audioheritage.org/vbullet...ead.php?t=4410

As for your frequency plots... they show exactly what I was talking about. Those peaks in the area that I shaded green are most likely all made up of ringing and other nonlinear products as well as being higher in amplitude. I imagine this is exactly what you were hearing. You can also see how the impedance has resonance related issues and the significant increase in distortion.


Widget