Taket Batpure - technical questions involving gain, stepup and maths ...

[montesquieu]

Intrigued by another thread I've stumped up for a pair of these

http://www.taket.jp/batpure/batpure.html

http://www.taket.jp/batpure/img/spec.gif

The specs are interesting, on the face of it about 70db (1 watt/1m I assume though that may well be wide of the mark), while the impedance is 4 kohm - I actually have little conception of what that means when it comes to a transducer but it would appear to be a bit odd.

My Tannoys are 90db/1w/1m and I am keen at least to try to match things.

I've tried all sorts of supertweeter experiments over the the years - probably most successful with Quad ESLs and Townshends - and had come to the conclusion that the 'benefits' they offer are usually are usually well in the audible band ie they fill in for a perceived gap in audible HF, where one exists. Though I have been intrigued by some experimental evidence that the body can somehow perceive frequencies far higher than our ears can be measured at (and avoiding for now at least the question of whether there's any meaningful programme material 'up there' - I'll be using mainly vinyl and my EAR 912 measures up beyong 50khz).

It's been suggested elsewhere that a step-up transformer of around 1:10 - easily available for phono use - might be about right to boost things from 70db to 90db, but I'd like to run that past the mathematicians here as surely that 4kohm must come into play. Also questioning whether an off the shelf phono stepup would have any useful (in phase at a minimum) frequency response above 20 khz.

Some people have got around all this by using these Batpures with dedicated amplifiers - would obviously need to be more sensitive than my 1v power amp, though that's not too hard - but it would seem that the only way to set the correct level for this sort of arrangement would be with a dedicated high frequency measuring device - not many microphones will read at 50khz.

This is only a bit of fun, for interest's stake and I don't want to spend a packet on it - but people have reported good results with these things and the wife complained recently on coming home from the house of her old professor (they have top end Tannoy supertweeters) why we don't have any as she thinks they add 'air' (we've measured her ears to 18khz rather better than my 11 khz so it may well again be the audible band she is talking about).

Anyway, I'm keen to give the supertweeter idea one last go and would appreciate the technical viewpoint.

[Stratmangler]

Why not just hang them off the back of the speaker terminals, as suggested on the website?
You won't damage them.

[petrat]

Bat-tweeters!! I don't remember Adam West having those ... :rofl:

It says max voltage is 150 volts, so using a transformer to up the voltage at your main speaker terminals by 10x might be taking it beyond its limits? Depending how they work, it may well be that you don't get any more volume from them by increasing the voltage, anyway. Better, maybe, to stick little horns on the front of them?

[Arkless Electronics]

Intrigued by another thread I've stumped up for a pair of these

http://www.taket.jp/batpure/batpure.html

http://www.taket.jp/batpure/img/spec.gif

The specs are interesting, on the face of it about 70db (1 watt/1m I assume though that may well be wide of the mark), while the impedance is 4 kohm - I actually have little conception of what that means when it comes to a transducer but it would appear to be a bit odd.

My Tannoys are 90db/1w/1m and I am keen at least to try to match things.

I've tried all sorts of supertweeter experiments over the the years - probably most successful with Quad ESLs and Townshends - and had come to the conclusion that the 'benefits' they offer are usually are usually well in the audible band ie they fill in for a perceived gap in audible HF, where one exists. Though I have been intrigued by some experimental evidence that the body can somehow perceive frequencies far higher than our ears can be measured at (and avoiding for now at least the question of whether there's any meaningful programme material 'up there' - I'll be using mainly vinyl and my EAR 912 measures up beyong 50khz).

It's been suggested elsewhere that a step-up transformer of around 1:10 - easily available for phono use - might be about right to boost things from 70db to 90db, but I'd like to run that past the mathematicians here as surely that 4kohm must come into play. Also questioning whether an off the shelf phono stepup would have any useful (in phase at a minimum) frequency response above 20 khz.

Some people have got around all this by using these Batpures with dedicated amplifiers - would obviously need to be more sensitive than my 1v power amp, though that's not too hard - but it would seem that the only way to set the correct level for this sort of arrangement would be with a dedicated high frequency measuring device - not many microphones will read at 50khz.

This is only a bit of fun, for interest's stake and I don't want to spend a packet on it - but people have reported good results with these things and the wife complained recently on coming home from the house of her old professor (they have top end Tannoy supertweeters) why we don't have any as she thinks they add 'air' (we've measured her ears to 18khz rather better than my 11 khz so it may well again be the audible band she is talking about).

Anyway, I'm keen to give the supertweeter idea one last go and would appreciate the technical viewpoint.

Head amps will generally go beyond 100KHz no problem. 1000KHz is quite possible.

[Arkless Electronics]

This may be relevant for some with supertweeters and vinyl.... phono stages which use series feedback RIAA don't continue to roll of the top end after 20KHz in the way the RIAA standard requires and could potentially have far too much output at say 40KHz.... Without seeing a circuit diagram for an individual unit I can't say which are affected. Passive eq and other types of active eq are not a problem in this area but series feedback eq is not in any way unusual, in fact it's the most common method in integrated amps, older units and some high end gear uses it too.

[montesquieu]

Jez, I'll be in touch directly, you might have answered my question!

[Wakefield Turntables]

I just bought a second pair from a neat little project I've planned for my Tannoys.

[brian2957]

I'm planning to do this too Andy :)

Please keep us posted on this .

[walpurgis]

I have a variety of supertweeters, but currently use none with the Tannoys. Tried ribbons and moving coil and found the nicest results were from Celestion HF2000 units. They just seem to blend in with the Tannoy top end well.

[montesquieu]

Jez and I discussed an active solution which is possible but I'm still curious about finding an autoformer that would do the necessary signal boost ... anyway the Batpures are on their way so we'll see if they do anything out of the box without a boost - who knows?

[Arkless Electronics]

Jez and I discussed an active solution which is possible but I'm still curious about finding an autoformer that would do the necessary signal boost ... anyway the Batpures are on their way so we'll see if they do anything out of the box without a boost - who knows?

An autotransformer was what I suggested! Active is in as much as I suggested a separate power amp of just a few Watts to drive it. This allows the super tweeter level to be set with the vol control on the separate amp and isolates the main amp from any undue load from the tweeter/autotransformer combination which may spoil the top end at audio frequencies coming from the main speakers. As we're talking 20KHz plus here a small ferrite transformer should do the trick.

[montesquieu]

An autotransformer was what I suggested! Active is in as much as I suggested a separate power amp of just a few Watts to drive it. This allows the super tweeter level to be set with the vol control on the separate amp and isolates the main amp from any undue load from the tweeter/autotransformer combination which may spoil the top end at audio frequencies coming from the main speakers. As we're talking 20KHz plus here a small ferrite transformer should do the trick.

Apologies Jez it's just me being too thick to understand what you were saying!

So how would it be set? Would I have to borrow some specialised kit to set the 'volume' (as it were)?

[Arkless Electronics]

Apologies Jez it's just me being too thick to understand what you were saying!

So how would it be set? Would I have to borrow some specialised kit to set the 'volume' (as it were)?

As I hinted in PM's there will never be any way of setting the "correct" volume or of measuring it. There is no tried and tested well worn path to success with something like this. By the very nature of ultrasonics you can't hear it.... nor are microphones available that are accurate from audio frequencies to 100KHz and the nearest to this that does exist costs a small fortune. It is going to be "suck it and see" whatever you do. I recommend a small chip amp ("gain clone" horrible phrase!) of maybe 5WPC with it's own volume control. This way you can continuously vary the output of the super tweeter, hopefully from zero to "too much"... quite how you gauge the correct amount of inaudible sound is something where your own subjective faculties are I guess where the buck stops. The batpures will look mainly capacitive load wise and then there is the effect of the autotransformer... meaning? Well meaning that the combination of batpures and transformer MAY put a nasty load on your main amp and tend to spoil the top end you CAN hear coming from your Tannoys! Using a small separate amp gets round this, as well as making it easy to vary the level of the batpures. Obviously for the "solution" described we are talking considerably more money than the £30 - 50 the batpures cost!

[danilo]

Odd... Why is it that septegenarians seem to gravitate to Super Duper tweeter "gizmos' .
When the typical 60 yr old ...Cannot... hear 14 khz? Unless perhaps a genetic Superman.

Possibly similar to Linn setups which some Males love.. while Wimmin often run screaming from the room the gear is playing in?
A ridiculous tilt to the Extreme frequencies so Granpa can hear an E string.

Don't actually care either way..... merely curious.

[Barry]

As has been commented elsewhere, whilst you cannot directly hear frequencies above 20kHz (unless you are asthmatic), and this falls to ~10kHz for the over 60s, you may be aware of supersonic information in the harmonic spectrum of instruments. Tannoy themselves market a supertweeter operating only above 10kHz, and higher.
tweeters
I see no harm in experimenting with these piezoelectric supertweeters. Just "suck it and see".

My own preferred solution would be to use a dedicated headphone amp with a 5W resistor of a few Ohms wired in series with the piezoelectric tweeter. Using a 10:1 step-up transformer will cause the capacitance of the load, as seen by the amplifier, to be increased by a factor of 100.

[Arkless Electronics]

:eek: £2500 for Tannoy's own super tweeter!!!

[Barry]

I think the Townshend units are ~ £1K.

(Just checked, the RRP is £899 inc. VAT)

[montesquieu]

As has been commented elsewhere, whilst you cannot directly hear frequencies above 20kHz (unless you are asthmatic), and this falls to ~10kHz for the over 60s, you may be aware of supersonic information in the harmonic spectrum of instruments. Tannoy themselves market a supertweeter operating only above 10kHz, and higher.
tweeters
I see no harm in experimenting with these piezoelectric supertweeters. Just "suck it and see".

My own preferred solution would be to use a dedicated headphone amp with a 5W resistor of a few Ohms wired in series with the piezoelectric tweeter. Using a 10:1 step-up transformer will cause the capacitance of the load, as seen by the amplifier, to be increased by a factor of 100.


I've played with supertweeters on and off for over a decade (having owned Fostexes, Townshends, Audio Smile and Tannoy supertweeters with different speakers in the past). Well aware of the limits of hearing (my own especially which measures to between 11-12khz, fairly typical for mid 50s, though the wife being in her early 40s hears 18khz).

Also aware of the research that shows frequencies above 20khz can have an effect on the body/brain (as recorded by MRI scans), mechanism currently unknown. And all the debates of whether there is 'music' up there or not blah blah di blah. I've seen the same utterly pointless threads pinging between believers/skeptics/agnostics for many years and not really motivated to repeat them.

I'm simply curious about these things and I'm now talking to Jez about a dedicated amp that will take the load off the main amp which seems eminently sensible. If they have an effect they have an effect, if they don't. I'm totally uninterested in any sort of 'debate' with anyone who isn't either 1) sat next to me or 2) is running a similar sort of experiment, the thread is here because I was looking for technical input.

[Barry]

Well that's put me in my place then! (And yes, I have been present at such experiments.)

[montesquieu]

Well that's put me in my place then!

Wasn't aimed at you Barry but rather to a post several above yours from one of the forum's regular wind-up mechants.

[Barry]

Ah understood - I was misled by your citation of my post, the first paragraph of which was in response to danilo's sarcastic comments.

[montesquieu]

Back on topic .. I've acquired an interesting 3D printing template for some stands for batpures (and there's a company in Holland which can run them up at reasonable cost) ... I ended up buying a pair of stainless steel factory made ones and selling on my 'loose' one, but I'm curious now what doubling Batpures up might sound like.

Can any of the technical boffins tell me what would be the best way to get maximum output from them - wiring in parallel (as they are at the moment with the main speaker) or in series? By parallel I mean wiring both pairs back to the amp individually, both to + or - respectively. By series I'm not quite sure what I mean (!) or even if that's possible.

They are a 4kohm load and 70 db efficiency so I'm looking to improve the overall output/efficiency from having two pairs. The 4kohm load as it stands seems to have no impact on the amp's performance.

[Firebottle]

Definitely wire them in parallel for max output.

In series each would only receive half the output voltage, so only 1/4 of the available power :(

[montesquieu]

Definitely wire them in parallel for max output.

In series each would only receive half the output voltage, so only 1/4 of the available power :(

Thanks Alan. :)

Would there be any impedance impact running them in parallel?

[walpurgis]

At 4kOhm impedance, in practise you could run as many as you wanted in parallel........... Half a dozen? :)

[montesquieu]

Cheers Alan. I might give it a go. (Two pairs I mean, not half a dozen!). Sorry for the noddy questions.

[walpurgis]

It was Geoff. Not Alan. :)

You certainly won't hurt anything using two pairs in parallel. That'll give you a 3db increase in output.

[struth]

yup the resistance drop is negligable

[montesquieu]

It was Geoff. Not Alan. :)

You certainly won't hurt anything using two pairs in parallel. That'll give you a 3db increase in output.

Whoops! Apologies.

[User211]

Whoops! Apologies.70DB efficient. Why is it so low anyone?

Getting a test mic on the output of these things would be really useful - given a good enough test mic and a high sampling rate.

I'd need to know what I was really getting before I could make any sensible judgements.

[struth]

mmn. i thought they were higher than that too. considered getting them but went another way

[montesquieu]

mmn. i thought they were higher than that too. considered getting them but went another way

I was very skeptical of reports that they did anything at all, until I tried a set. Whatever they are doing - and it could be some comb filtering effect - they certainly do have an impact on the sound, and not just in the high frequencies. Any supertweeters I've tried other than these put out something audible from 8-10k, these don't.

I guess having two pairs would only increase the output by what, 3db? But might be interesting regardless.

I did stick a reasonable quality gainclone in as an experiment, driving them directly from that, in an attempt to cover for the mismatch in sensitivity, but without a suitable measurement setup I was just messing around really, and things sounded more 'right' running them off the main amp.

[walpurgis]

Any supertweeters I've tried other than these put out something audible from 8-10k

If that's the case, there was something wrong with the setup. The filter was rolling the units in too early from the description. There should be no audible output from supertweeters.

[montesquieu]

If that's the case, there was something wrong with the setup. The filter was rolling the units in too early from the description. There should be no audible output from supertweeters.

Well you could certainly hear something from Townshends I've owned, and Tannoys, and Audiosmiles ....

[farflungstar]

The takets are reportedly the only ones to be silent - I've toyed with trying their batpure further up the range, open backed as I think this could add some extra ambience - but the new Tannoy look sooooo lovely.

[walpurgis]

I set up my own supertweeters and filters, which were carefully tuned to avoid audible output. But, you could certainly hear a difference in the sound when they were taken out of operation.

I've not used any for years though. I have many suitable drivers, but can't be bothered to be honest.

[walpurgis]

The takets are reportedly the only ones to be silent

All supertweeters will seem silent if used properly, i.e., filtered to come in above the audible treble output from the main tweeter.

[struth]

Ive heard output as well but if, as Geoff says, the right filter is on it, you shouldnt

[Chris]

I have external crossovers placed next to my amp. Could I run these things straight from my tweeter terminals i.e. post crossovers or would something nasty happen impedance wise ?

[montesquieu]

I have external crossovers placed next to my amp. Could I run these things straight from my tweeter terminals i.e. post crossovers or would something nasty happen impedance wise ?

That's what I do. Their impedance is very high and I'm repeatedly assured that it's nothing to worry about.

[walpurgis]

Yes you can. Their impedance is so high it won't bother the crossovers or main tweeters or affect their operation.