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Super Tweeter

eguth

eguth

pfm Member
Memoirs of a DIY HI Fi Nut - Part XX

SUPER TWEETER

I​

No, I have not joined Twitter, much less begun to boast about my prowess. I have bought a super tweeter. The DIY bit comes in hooking it up, mounting it on a dedicated plinth and orienting it.

The unit goes by the name of BAT-PURE, or ‘TAKET BAT-PURE’ to give it its full name.

This little beast is tiny- about the size of a throat lozenge. You cannot hear any sound coming from it even at full normal volume with your ear as close as possible. So how does it work? And does it work?

In view of its low cost (5,800 YEN- £43.60 including airmail from Japan) and because it sounds silent I first thought it a hoax depending on suggestion for its effect.

It comes with a ‘Manual’. This is a couple of pages in Japanese English. I found translation into English difficult. I quote from the ‘Manual’:

“…confirmation sound’s whether it having been emitted; the main speaker is removed. Only BAT PURE is connected with the amplifier…please maximise the volume of the amplifier…no breakdown if it faintly hears of the sound.”
II​

The specs are:
SPL 20KHz-150kHz about 70dB 1m
maximum voltage 150V
mass- about 1 gram
impedance 4K OHM (DC-100KHz)
polymer piezo- electric monomolf film
(no frequency response graph provided).

The unit is connected in parallel with the tweeter or midrange driver. No crossover. The recommended sites are above the tweeter or on top of the cabinet or on the walls.

Piezos have a bad reputation, but I have heard Motorola tweeter horns sound excellent.

Whatever the virtues of uneven response, ever since reading DICK OLSHER’S excellent 2004 review of the muRata ES103A Super Tweeter I have been looking around for a much less expensive alternative. The ES103A uses a piezo.

Next instalment, a myth knocked on the head.
 
I use a pair of Pioneer TAD PT R7 ribbon supertweeters.

I xover them at 10khz and they run to 100khz at about 92dbw. They are of the if you have to ask the price you cannot afford them. I got them 2nd hand for a good price.

If you use a supertweeter and it x over at 20khz you will not hear it. I doubt you would hear above about 16khz at age 45. Also the efficiency seems pretty low so hearing them at that efficiency with your speakers would mean you might not hear them.

So what is audible above 20khz on a cd well nothing. Vinyl not a lot Tuner nothing above 12-15khz. Tape not a lot above 15khz.

The only medium i know that has anything above 20khz is SACD. So i use a SONY SCD 777 ES SACD and playing an SACD disc you can hear a diffrenece between the cd and SACD layer with the supertweeter in.

David
 
daytona 600

Good link; I was not aware that it was that good. I will transfer the Bat-Pures to my Grado SR325s after I die, so that I can enjoy enhanced reproduction in the next world.

DAVOhorn

Have you read the scientific research papers on human hearing above 20K Hz? I gave some references in my earlier Memoirs. Much the best discussion I have found in this area is by Martin Colloms. He is a skeptic (you can probably access this via the Hi Fi Critic website). Try:

http://www.hificritic.com/downloads/Archive_A10.pdf


In my next instalments I hope to stretch your credulity even further.

Regards,
eguth
 
Super tweeters 'work' by impacting the audible HF range and by modifying the power response and dispersion characteristics. This has nothing to do with output >20khz.

The benefit depends entirely on the loudspeaker system they augment, and the room in which they are used. Sometimes they result in worse performance.

In some cases where a loudspeaker system on-axis response rolls away early and falls short of 20k, additional tweeters can of course restore the missing output but they will need careful integration.
 
Robert

"...Super tweeters 'work' by impacting the audible HF range and by modifying the power response and dispersion characteristics..."

Are you able to provide references for your assertion?
 
Robert

Your assertion flies in the face of the research as well as in the face of common sense.

The research demonstrates that ultrasonics are perceived and that they affect our brains, though we don't hear anything.

The higher the frequency the narrower the dispersion, so the higher the 'beyond hearing' frequency the less and less effect the room has on what is sensed (perceived by the brain).

A super tweeter that goes up to, say, only 25 K Hz is a MISNOMER, as would be one that goes up only to 30 or 40 K Hz. Such inadequate extension does not enable reproduction of ultrasonics on some records cut with a Neumann head, much less SACD etc.

If a super tweeter affects the sound from the tweeter because it is reproducing frequencies in the tweeter's frequency range it goes too low. The fault arises through use of filters or crossovers connecting the super tweeter.

This problem is not one the BAT-PURE suffers from. It does not utilise a filter or crossover.

Super tweeter's effectiveness has everything to do with how high the frequencies it can reproduce extend and everything to do with what has been recorded up there- if anything.
 
Surely most amps roll off just above 20khz? Save the designer worrying about widebandwidth linerarity and ocislation above the audio band?

Stefab
 
The Bat Pure does not use a filter or crossover? Really? I think you mean the Bat Pure's high pass filter is built into the mechanics and electrics of the device without recourse to additional filters constructed of caps, coils and resistors. Not quite the same thing at all....
 
Robert said:
Super tweeters 'work' by impacting the audible HF range and by modifying the power response and dispersion characteristics. This has nothing to do with output >20khz.

The benefit depends entirely on the loudspeaker system they augment, and the room in which they are used. Sometimes they result in worse performance.

In some cases where a loudspeaker system on-axis response rolls away early and falls short of 20k, additional tweeters can of course restore the missing output but they will need careful integration.
Click to expand...

I have been using piezo horn tweeters on Quad 57's since I read an article by Jimmy Hughes in Hi Fi news & Record Review some 20 years ago, there is a capacitor & resistor in circuit; values I can't remember.

At the time I was in my 40's, at that time I could hear up to 16-17 Khz (at the time I was an amateur involved in the car stereo scene and regularly used frequency sweeps) I seem to remember Hughes set the high pass filter (capacior) to prevent much under 18khz I could not hear musical output only vague hiss My young daughters could however hear them. In my room the "super tweeters" worked.

Despite believing I was hearing a large difference "snake oil" was as prevalent then as now along with the psychological effects of belief ; so not even trusting my own ears, I did a blind test. I had friends swap tweeter leads on/off , then we did the same for them. All of us could easily tell the difference...

Late last year I obtained a pair of One Thing Quad 57's, Having evaluated them after a couple of weeks, I fitted the "super tweeters" I still got the improvement to bass & midrange my 18 year old son can hear them...

I am of course now in my 60's, I have a B&O sound system in my new car, not quite what I used to have & design but fitted at factory & a lot cheaper with no fuss, I used frequency sweeps to set it up, not bad I can still just hear 14khz and no tinnitus the benefits of not listening to painfully loud music.

It has been asserted "Super tweeters 'work' by impacting the audible HF range" If so how did I hear the difference 20 years ago, or more questionably now. as my hearing is well below audibility at 14khz...

I do not have an answer, though I believe "eguth" is nearer the mark...

I intend to buy a pair of BAT PURE as my piezo's only go up to 40khz'ish.
 
The supertweeter modulates the audible range by interacting with it directly, you hear the modulation of the audible signal not the inaudible frequencies themselves.
 
Details of the BAT-PURE’S construction are given on the TAKET website under ‘Technology’.

The unit dies not utilise a filter.

No information is provided as to what- if anything- the response is below 20 KHz.

A full range driver that goes from DC to the high ultrasounds will be developed I hope, in due course, by someone somewhere.

In future there will (possibly) be ways of experiencing reproduced sound that have yet to be conceived .
 
sq225917 said:
The supertweeter modulates the audible range by interacting with it directly, you hear the modulation of the audible signal not the inaudible frequencies themselves.
Click to expand...

Intermodulation was pretty much what I concluded, however since my evidence is empirical not scientific I was not about to postulate in print
 
Memoirs of a DIY HI Fi Nut
Part XX
SUPER TWEETER

III​

Let’s knock one myth on the head immediately. There is research showing that even the elderly can detect differences in sounds at 60 KHz.

Dick Olsher states that although ultrasonics cannot be heard scientific evidence, including PET scans, demonstrates central blood flow activity in response to ultrasonics.

Research is on-going in respect of using ultrasound to assist deaf people. Even the severely deaf who are deaf in the audible range respond to ultrasound.

Olsher maintains that the higher a tweeter goes the faster it sounds. That said, although the Neumann cutting head records frequencies higher than 60 KHz, if the system on which a record is played back cannot reproduce what is on the record Super Tweeters will be a waste of time, won’t they? Well, yes, apart from Olsher’s point about speed, which will (possibly) apply when listening to CD or even FM radio.

So…before going any further I will outline my system.

My current MC cartridge is a Dynavector XX-2 MK II. Dynavector quotes a frequency response of 20-20KHz but they do not say anything about what is emitted above 20 KHz. Nor does the B&K response graph help. It just displays a ‘brick wall ’drop at 20K. We can be certain that the frequency response does not immediately drop to nothing above 20 KHz but rolls off. The question is at what slope and how high it goes before there is no output. On the assumption that the cartridge has some output up to, say, at least 50-60 KHz the ability of the BAT-PURE to do its job depends upon what follows the cartridge in the hi fi chain.

In my setup the signal next goes into a MC transformer, a NAGATRON Z Coupler (Ag 9200) with a frequency response claimed as 10Hz to 50 KHz. Again, no details are given of response above 50K, but we can reasonably assume some output above that.

Next my preamp. It started life as a bog standard Quad 44 but has been extensively modified (see my Memoirs Part XVIX ‘Quad 44 preamp Upgrades’ for details, especially Part V- ‘POWER MAD’). Frequency response was tested via the tape output on a scope after the mods. It extends higher than 200 KHz (200+). Thus it flies higher than even the BAT-PURE.

I only use the modified ’44 through the tape output, so the usual mediocre performance down to the rest of the Quad 44 circuit when the preamp is used in the conventional way is largely avoided.

I am tri- amped. After the passive preamp (with active buffer stage) the relevant ultrasonic signal goes to my BK mosfet monobloks. These have been modified to go up to 100 KHz. The BK monobloks amplify everything above 4 KHz into my tweeters (Morel horns) after going through the high pass filter.

I soldered single strand OFC silver- plated PTFE insulated wire, using silver solder, to the BAT-PURE terminals. The other ends were terminated into Hirschmann test plugs. These plug neatly into the rear of the 5 way binding posts on the tweeter terminals.

After some experiments I mounted the super tweeters on small triangular pieces of mahogany moulding so that they fire upwards at 45 degrees. I tried various sites and ended up putting them about 12” above the tweeter, vertically aligned with it, on top of the concrete block that sits on top of the cabinet.

IAN RAWES, of the London Sound Survey, came over with a Bat Meter- an apparatus for determining the frequency response of sounds made by bats. He used it to measure the output from my super tweeters.

Next instalment: the measurements.
 
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