Midrange dome drivers banned ?

[dualazmak]

Thread notice: Let’s all take a few deep breaths and remember we’re here to share our passion for Music and it’s reproduction. Any further personal insults will result in Warnings and Thread Bans.
Carry on and enjoy this Sunday afternoon!

I fully agree with you.

Now, let's go back to valuable communication on "midrange dome"!

 

[jtgofish]

My NS-1000(rev) is now fully renovated eliminating the LC-network and each of the SP drivers is directly driven by dedicated amplifier. Furthermore, I added super-tweeters and L&R rather large and heavy active sub-woofers YST-SW1000. Consequently, the sound of my present multichannel multi-driver multi-way multi-amplifier system with NS-1000(rev) is now far away and much different from the original sound of neat intact NS-1000 for which you are referring... Now, I can well hear the image depth or 3D sound perspectives with my system, and nice "disappearance" of all the SPs. Of course, my listening room environment is one of the critical factors for the wonderful total sound.

If possible, I really would like to invite you to my home for our listening sessions.

Yes I would like to hear your system one day.Clearly the speakers you use are now a long way from being NS1000s and are just a speaker that uses some NS1000 parts.Your signature says you you NS1000s so I assumed they would be NS1000s and hence they would suffer from the deficiency I mentioned [as well as the other one I did not mention which is the use of a woofer with a low Qts in a sealed box when it really belongs in a much larger ported one].I always felt the NS1000s had huge potential to sound much better and have no doubt you have managed to turn them into something really good with your extensive modifications.
My apologies for accusing you of being unable to hear imaging.Clearly you can or you would not have gone to the trouble with all your modifications.

 

[jtgofish]

jtgofish
You are obviously one of the trolls that the audio snake oil industry sends this web forum periodically. You are certainly entitled to wrong opinions but to imply that dualazmak can't hear is insulting and inappropriate and I hope the admins here give you a well deserved timeout. Just for your information the person you are insulting is not only a musician but an highly published scientist with a VERY long CV and list of publications. He KNOWS how to experiment and how to take measurements! And how to interpret them.
Some people prefer to perfect their systems through a combination of scientific experimentation and rather than just spending money at the yacht club stereo store. Just the diagramming dualazmak submits to these pages is more effort and value than two dozen "golden eared " useless opinions.
I invite you to find a web forum that is more in tune with your "values".

BTW "center fill" and "image depth" not only are room dependent but are mainly illusional , not measureable and completely subjective. Sort of like the "stereo" of pop music that only ever occured inside a mixing console but was never a real acoustic event in time and space. As someone who has been a professional microscopist and photographer and longer than I have been interested in audio (which is about 53 years ) I have always found the "imaging" analogy extremely defective. Sound systems really don't image much. What they do is more of, is to create an illusion. The "image" is created in your brain.

The whole point of stereo recording ,reproduction and ownership is imaging.

 

[gene_stl]

But stereo is quite obsolete. There are numerous exciting multi channel options that render stereo "so 20th century".
I would say the whole point of stereo is to expand it to at the very least 5.1 if not a greater number of channels.
I got interested in multichannel two to three years ago and although the system is not yet setup I have already amassed a really wonderful collection
of source material.

 

[dualazmak]

Hello friends,

Going back to focusing on "midrange dome",,,

The general consensus for Yamaha's abandonment of using Beryllium dome would be;

1. Potential toxicity of Be if the driver would be broken into particles or powders,
2. Yamaha's protective measures in terms of social responsibility for potential environmental pollution,
3. Lack of engineering continuity/transmission within the Company due to their (tentative) withdrawal from the HiFi speaker market,
4. Many excellent engineers involved have already retired or even passed away,
5. Revival of Be-dome would be far above their cost-profit perspectives,
6. other factors

Yamaha is such a big company, and I believe we cannot expect Yamaha would come back to Beryllium at least in the near future.

On the other hand, I assume and highly expect that smaller audio dedicating companies, such as TAD (Technical Audio Devices Laboratories, Inc.) and BlieSMa (developing 3" Be midrange dome?, see here), may possibly continue developing nice "vacuum metal deposition type" Beryllium "midrange dome", in safe manner, I hope.

 

[Doodski]

The general consensus for Yamaha's abandonment of using Beryllium dome would be;

I think the previous (think 1980s and 1990s) inventory levels of the Be drivers was difficult to maintain. That was indicated by the limited global inventory levels of the Be product. That limitation might be the same now.

 

[dualazmak]

Sorry, but @headshake already touched on Bliesma Be domes here in this thread.

 

[gene_stl]

There are a number of Be drivers available most of which are tweeters. They all utilize Beryllium formed from sheet by a company in southern California.
I have not seen any information that anyone makes them by vapor deposition the way Yamaha did. I would imagine then that the diaphragms/domes are more massive than the Yamaha product. I once saw, (I don't remember where ) a claim that the 33 mm tweeter diaphragm without the voice coil and former was only 35mg. (in the Yamaha product)

 

[dualazmak]

According to TAD, their CST Driver in TAD Reference One TAD-R1TX and TAD-CR1TX consists of coaxial 16 cm midrange corn (not dome) plus 3.5 cm tweeter dome, both "vacuum metal deposition" Beryllium metal. The say TAD is the only one company maintaining they production technology of that Be corn and dome;
https://tad-labs.com/jp/consumer/r1tx/

The CST Driver covers 250 Hz to ca. 100 kHz. The crossover from Be-corn to Be-dome tweeter is at 2 kHz, and hence the Be-corn (not dome though) covers 250 Hz to 2 kHz.

I really would like to listen to (very much expensive) TAD-R1TX at their studio in Tokyo when the COVID-19 pandemic would be well subsided.

 

[jtgofish]

Usher has used beryllium midrange drivers for some time.Not domes though.

 

[Doodski]

All technology aside the woodgrain finishes are gorgeous with those 150kg cabinets. I want to know the vapour deposition process and assembly time for those drivers. I imagine depositing vapour is not a fast process.

 

[dualazmak]

I could find this promotion article for TAD-R1TX;
https://www.phileweb.com/news/audio/201906/28/20973.html

 

[Doodski]

Reading a little on the process of Be vapour deposition process.
- Heat of Vaporization 73.9 K-cal/gm atom at 2467 °C
https://www.americanelements.com/beryllium-pellets-7440-41-7

This source states that they where depositing at 1 mil/hour (1/1000 of a millimeter) @ temperatures of 280C-305C. So how many mil thick are these tweeters and the midrange driver?>
https://www.osti.gov/servlets/purl/4583215

 

[Doodski]

This source states that their deposition process deposits at low rates. A tweeter would require some hours for the deposition process.
https://patents.google.com/patent/US3450558

EXAMPLE II Substrate.Mild steel cylinder, /2" diameter x 1 /2 long Substrate temperature.289 C.
Compound temperature (preheater).l83 C.
Pressure.0.70 mm. Hg
Time-105 minutes Coating thickness.--0.8 mil Plating rate.-0.46 mil/ hr.
Results.-Smooth, light gray, metallic, adherent, and coherent coating.

EXAMPLE III Substrate.-Mild steel cylinder, /2" diameter x 1 /2" long Substrate temperature.300 C.
Compound temperature (preheater).196 C.
Pressure.0.8 mm. Hg
Time.--105 minutes Coating thickness-averaged 1.6 mil Plating rate.-1.1 mil/hr.
Results.-Srnooth, light gray, metallic, adherent, and coherent coating which assayed at 94.8 weight percent beryllium.

EXAMPLE IV Substrate.Mild steel cylinder, 1" diameter x long Substrate temperature.287 C.
Compound temperature (preheater).l75 C. Pressure-0.3 mm. Hg
Time.450 minutes Coating thickness.--Averaged 1.7 mil Plating rate-0.23 mil/ hr.
Results-Light gray, metallic, adherent, and coherent containing a few tiny nodules. A portion was removed and assayed at 9.8 weight percent beryllium.

EXAMPLE V In the following runs a similar apparatus arrangement was employed except that the substrate was positioned on a rotating hotplate and heated by conduction. The temperature of the substrate was indicated by a thermocouple welded to the surface of the hotplate. Argon was utilized in lieu of hydrogen for purging the plating chamber of residual oxygen.
EXAMPLE VI Substrate-Aluminum disc, 1%" diameter x 0.04" thick Substrate temperature.370 C. Compound temperature (preheater).25 C. Pressure.1.25 mm. Hg Time.3.3 minutes Coating thickness-03 mil Plating rate.5 .4 mil/hr. Results-Light gray, metallic, adherent, and coherent coating.

EXAMPLE VII Substrate.8 sapphire discs, each 1 cm./ diameter x 1 mm. thick Substrate temperature-256 C.
Compound temperature (preheater).25 C.
Pressure.0.42 mm.
Time-45 minutes Coating thickness-26 mil Plating rate..34 mil/hr.
Results.-Light gray, metallic, adherent, and coherent coatings containing a few tiny nodules.

EXAMPLE VIII Substrate-8 glass squares, 0.7 cm. length x 1 mm. thick Substrate temperature-290 C.
Compound temperature (preheater).-25 C.
Pressure-0.90 mm. Hg
Timeminutes Coating thickness-58 mil Plating rate.1.7 mil/hr.
Results-Light gray, metallic, adherent, and coherent coating on each member, with some having a few small nodules.

EXAMPLE IX Substrate-4 fused quartz discs, 1 cm, diameter x 1 mm.
thick.
Substrate temperature.--2S4 C.
Compound temperature (Preheater). C.
Pressure-0.70 mm.
Time.--18 minutes Coating thickness-.14 mil Plating rate.-.47 mil/hr.

 

[Frank Dernie]

Reading a little on the process of Be vapour deposition process.
- Heat of Vaporization 73.9 K-cal/gm atom at 2467 °C
https://www.americanelements.com/beryllium-pellets-7440-41-7

This source states that they where depositing at 1 mil/hour (1/1000 of a millimeter) @ temperatures of 280C-305C. So how many mil thick are these tweeters and the midrange driver?>
https://www.osti.gov/servlets/purl/4583215
View attachment 146488

This begs quite a few questions, for me.
On ASR the general "official" opinion is that it is the frequency response and directivity which are the first order parameters for favoured SQ.

It seems that both of these can be achieved, at a modest maximum output, with inexpensive cabinet constructions and cheap if well engineered driver designs.

This rather begs the question have I been wrong to believed for decades the narrative that having an inert enclosure and low distortion, preferably pistonic, drivers is critical for top level SQ?

It seemed plausible and I was sure the cabinet modifications made an improvement in sound on my DIY speakers (almost 50 years ago now) but now I keep reading that the very expensive engineering required to achieve inert drivers and enclosures may be not needed.

It is hard to get my head around and flies in the face of what I had taken to be "common knowledge".

In any case my friend who designs drivers tells me he has designed a driver for a client using computer modelling to produce designs with linear magnetic circuit and pistonic metal diaphragm which has a distortion of ~0.1% in its passband which could be used as a mid driver in a HiFi which is being mass produced at a cost of €1 per driver.

 

[gene_stl]

It is interesting that TAD says they use "the original technology". Perhaps the lab where the diaphragms were made was an independent third party contractor.

The patent Doodski cites is owned by the US Atomic Energy Commission. They use Beryllium for weapons production.

 

[gene_stl]

Frrank Dernie said:

It seemed plausible and I was sure the cabinet modifications made an improvement in sound on my DIY speakers (almost 50 years ago now) but now I keep reading that the very expensive engineering required to achieve inert drivers and enclosures may be not needed.

It is hard to get my head around and flies in the face of what I had taken to be "common knowledge".

In any case my friend who designs drivers tells me he has designed a driver for a client using computer modelling to produce designs with linear magnetic circuit and pistonic metal diaphragm which has a distortion of ~0.1% in its passband which could be used as a mid driver in a HiFi which is being mass produced at a cost of €1 per driver.

I have seen a lot of this too and it is also consonant with some very informal experiments I have done that lead me to believe that much lower priced gear can achieve an amazing SQ at much lower prices. This is one of the reasons I rail against over priced equipment.

Is your friends driver design a dome??

 

[Newman]

This begs quite a few questions, for me.
On ASR the general "official" opinion is that it is the frequency response and directivity which are the first order parameters for favoured SQ.

That's a fair summary. And highly logical too.

It seems that both of these can be achieved, at a modest maximum output, with inexpensive cabinet constructions and cheap if well engineered driver designs.

"Well engineered" is never cheap, even if the final product can be cheap to make.

But I am yet to see a final product that is cheap to make and delivers an extremely flat directivity all the way down to 500 Hz, or maybe 300 Hz is the ideal target, and an extremely flat FR from 20 Hz to 20 kHz, that is extremely constant over a 2mx2m listening area, and is not prone to floor and ceiling bounce effects. Plus sufficient headroom at all frequencies to deliver a seriously loud experience without dropping the ball.

This rather begs the question have I been wrong to believed for decades the narrative that having an inert enclosure and low distortion, preferably pistonic, drivers is critical for top level SQ?

Yes, probably. The definition of progress is that previously held beliefs are contradicted. If the best available listening test data says some old beliefs are not validated -- we have progress.

There is no harm in firmly believing they were absolutes before the new evidence. Adopting the best available knowledge of the past is fair enough, but getting stuck to it once contradicted by new data is anti-progress.

It seemed plausible and I was sure the cabinet modifications made an improvement in sound on my DIY speakers (almost 50 years ago now) but now I keep reading that the very expensive engineering required to achieve inert drivers and enclosures may be not needed.

We have also learned enough about the nature of human perception to doubt our old listening impressions, if they were not gained with gold standard listening test controls.

It is hard to get my head around and flies in the face of what I had taken to be "common knowledge".

Letting go is never easy, but that is the real step we need to take when faced with rigorously-tested progress.

In any case my friend who designs drivers tells me he has designed a driver for a client using computer modelling to produce designs with linear magnetic circuit and pistonic metal diaphragm which has a distortion of ~0.1% in its passband which could be used as a mid driver in a HiFi which is being mass produced at a cost of €1 per driver.

Sounds great.

cheers

 

[Frank Dernie]

Is your friends driver design a dome??

No

 

[dualazmak]

Amazing, thank you all.

Really nice information exchange and discussion in progress today while I was rather trapped by my daytime duty related to the COVID-19 re-increase in my district.

You all are adding much knowledge of Beryllium corn, Beryllium dome, and other midrange and tweeter drivers. Yes, this is really ASR!