REL Quake

Tony,

I'm not alone here. I designed my "subs" to work over four octaves. Similar systems are used by Tact and Titian. Most big three ways use bass drivers up to 500hz or so - so think of it more as a three way than most people's idea of a sub.

I currently crossover 2nd order at 200hz with the main speakers unfiltered and I love it! The imaging is excellent (if you like that sort of thing), and the palpability of vocals and instruments is vastly improved. Plus I might add, the music is driven along in a manner that would keep the tune brigade happy.

I have yet to hear a subwoofer that fills in the bottom octave acheive anything like that, which is why I designed my own. Sadly most commercial subs are designed with AV in mind to my ears.

 

Is that what you call good bass...

I will stick with my REL Stratas, thanks...

 

Dunc,

If you look at the green line in the middle, that's the response that the Tact corrected to. The extra level of the subs was only at the measurement - the correction brought it down to match the satellites.

The suckout was a symptom of a 2 x 1 x 1 room sadly, a triple node.

 

Err, flat to 15hz? Yep, I'd say that's not bad and eons beyond the capabilites of your little boom boxes

 

Ah, I gotcha Merlin. Is the green line the measured response after Tactification, or some kind of "predicted response"? If it's measured, then I bow down to you and/or Tact.

And does that indicate that the Tact was able to EQ out the suckout? Seems unlikely given the nature of such things...

Dunc

 

Interesting. I've not heard of that technique before. I'd also not quite understood the graph as being a 'before' and 'after' with the centre bit being the Tact corrected system – its certainly impressive on paper, though seems to dip down a fair bit in the extreme top. Is this deliberate?

I'd love to see a response plot of mine – my guess is that its pretty smooth as I have a very clean sounding room and very well behaved speakers. There is no bass boom noticeable at all, it's very even down the bass neck (easily demonstrated with my fretless!), but I think I have next to nothing at all below about 50Hz and a slight lift in the top end. It sounds very natural and groovy but lacks a little weight or what audio magazine types call slam.

Tony.

 

Look at yourself man Your now reduced to playing with words in order to construct a tautology by using the word proof in the mathematical sense, rather than its common meaning "facts, evidence argument etc. establishing or helping to establish a fact" (OED BTW).

So, is there enough evidence to show (oops almost typed prove) that Mana works beyond reasonable doubt?

Argument For: mana users attest to its effect.

Argument Against: Many other people - who have tried mana, but have considered it not to work, remain silent, and don't bother publicly proclaiming it "merely furniture". We assume they are out there, but these folks are obviously not contributing to the mana forum.

For: it's been positively reviewed in the press.

Against: everything positively reviewed by the press. Reviewers hearing no better than anyone elses. Reviewers part of the "conspiracy" to keep advertizing revenue coming in from stand manufacturers and hence keep their jobs. No attempt at objective assessment: reviewers don't have to show that they can actually hear what they claim in reviews. In short, reviewers as gullable as the buying public. Reviewers don't review Ikea etc, because there is no advertizing revenue.

For: it actually functions as a stand, ie you put equipment on it and it doesn't fall off.

Against: cost

For: height adjustable

Against: height adjustable, simplistic more is better philosophy (it actually is financially better for the manufacturer) doesn't mesh with the acoustics (speakers get too high).

For: it's used in studios by at least three people (Roger Waters, Embrace, Paul McCartney).

Against: (Almost) universal studio rack: the 19" rack. Equipment bolted directly to frame with no "vibration isolation". Similarity to Mana? none, other than made of steel

(Your) Science of Mana: "[with Mana] play louder without strain or distortion" "vibration sink" "reduces cabinet vibration".

Actual (verified) Science: none - not a single measurement, graph, technical report etc, to substantiate the above claims.

In summary: the proclamations of the faithful on the mana forum (biased), but we can't be sure how many detractors there are as they don't have a "bitch about mana forum"; the reviews produced by journalists, who know the equipment they are reviewing and who are paid by advertising revenue (biased); and a small set of "elite" users who've given Mana a soundbite, but not a proper testimonial, and again, we don't know how many studios tried Mana and then returned it for a refund. Oh, and we have some "voodoo science" - some superficial scientific explanation dressed up to sound plausible, but with no experimental evidence to back it up.

Let me talk to the Doctor in The Devil: if some drug company salesman rolled up in your office with some (claimed) miracle cure and said: trust us, there's a web forum of users who rave about it (ie those who haven't died), a great review in Good Housekeeping (but not the BMJ), Paul McCartney takes it, but we didn't bother testing it because there is only Mathematical Proof, what would you do?

 

Isnt the tact response curve in Merlins room like the classic BBC loudspeaker response? its defo deliberate IIRC, as when I was over at merlins he showed me a number of different curves, the flat curve didnt sound as good as some of the tailored curves.

 

Dunc,

it is what is known as a "target curve" , programable by the user to give the Tact something to aim at if you like. How close the final response was I really don't know, although crude measurements with a sweep and SPL meter suggest it's not far off. You would need two Tacts to measure the corrected room response.

Again in this extreme case no, although once again I set the levels of the subs high to bring the bottom of the dip up and reduce it's effect on the mean level. The Tact would merely attenuate the rest of the subs' output. Given the narrowness of the dip it was not too much of an issue - wider, shallower suckouts would create a greater problem I suspect.

The proof as they say is in the listening, and in this particular case, a room that pre eq sounded like there was nothing below 100hz(which effectively there wasn't), now had "sufficient" bass to amuse visitors!

Tony,

that curve is totally customizable and yes the roll of in the treble was deliberate on that one. You can store nine such curves, so that is just one example and was ideal for replaying a lot of CD's. As Robbo found out, rolling off the HF did not have the effect of making the treble seem any less extended, more of giving greater body and bass warmth. It's surprising the things you can learn with one of these things.

I supect the Tact will be getting a decent review in HFN next month. Keith Howard has had the system for 18 months, but it is only recently that Tact have started paying for full page ads

 

Oh and DAT, would you kindly post something categorically disproving what Bub and others claim? Alternatively please discuss your experience with Mana.

Your posts really do make you come across as rather naive, which i am sure is not the case. How about discussing the following

What technical measurement comes the closest to predicting the sound of a piece of electronics or speakers, and why?

At what point in the design of a component do you switch from using measurements to listening?

Finally, do you think we will ever see the day when we have a set of measurements that will accurately predict the sound of a component?

 

Tony,

A man of your wisdom, not heard of using the main speakers as just mid band/upper frequency units and crossing the subs higher to act as mid bass and helping total intregration, shame on you!!! have to include that one in your new book.
Tact & Groove eh? to quote a famous Phrase, 'That'll be the day '
I will say it produced one of the best images I've heard, in a room that was little more that a shoebox, quite outstanding
Although when using on a non tact amp it robbed over 40% of the Volume to use for making time alignment and indivdual driver level adjustments as well as the involvment factor.
The newer tact amps seem to able to do dynamics better.
One bonus of measuring the room, was finding the speaker intergration points left speaker .4m/s before the right, a simple placement correction worked wonders.
Prehaps I should measure the room again, after all 17 months is along time.

 

Suckouts are almost impossible to fix, would need tons of power to get close, no seller of EQ recomends that you try that...

Xover above around 80hz should be designed specifically for that speaker, I mean box, drivers, etc, to acomodate phase, time delay, ressonances, etc, you should stick to the usual low cut-off frequencies to get reasonable integration when using subwoofers... :JPS:


The more EQ, and the higher the frequencies, the worst sound you get...

 

I am a drug company salesman, and the above argument is very good, however, where this argument falls down is, a doctor needs proof of medicines effectiveness, because.

Doc is not end user, patient is so has to be nore vigilant.

Mana won't kill you in normal use, ie i does not affect bodies metabolism, and would not interact with your othewr equipment causing death.

Proof with drugs is based on measurable parameters, then any differences are expressed mathematically.

All drugs on the market in UK have been through 3 phases of trials mainly safety, the post marketing trials come after drug has some use in the community.

Docs will use drugs with little evidence if company puts enough money behind it and makes this money available to heads of department.

Drugs will be used if very pretty Blonde female rep sells it, John Watson is not pretty so no incentive there.

Oh and Mana is used purely to enhance a hobby and it is trivial to compare to life saving drugs, which are chosen for objective rather than subjective reasons.

Dat I have never tried Mana in my own system, I have heard it in Bubs sytem but never heard that system sans mana, does it work, I don't honestly know either way, and as a result would nebver try to say it is a lotta rubbish, It looks ugly but again that is a matter of taste, I would never wear orange trousers but some would.

So dat before bouncing back any of Bubs arguments lets here some of yours,
You mentioned drug trials so letas start there.

How many people did you recruit for your trial, was there any runout phase of old equipment, what were you compairing it too, and what was the control, was it double blind, single blind, or open label, how often did you take measurements, who measured these results(were they qualified), where are the results published, what type of bell curve did you apply to remove spurious results, what was the mathematical significance of these results. I could go on as drug trials have so many different parameters but these are enough to be getting on with.

You are asking bub to prove all these, then surely we can expect the same from you, it doesn't work and heres the proof.

Bub has answered all your arguments and doesn't have proof in this VERY subjective matter, his posts are meant to help others into decideing for themselves, you are trying to make a fool of him, but with the circular argument you are using it's you that is looking foolish, you have yet to answer any other posts and it now seems as if you are mearly attacking Dr McP and don't have solid basis for your argument.


Dat put up or shutup

Paul

 

Hi dat,

I think you might need a little lie down.

It would be a relatively easy thing to do for you to get hold of a s/h Mana rack, place your CDP upon it, and listen to a couple of your favourite CDs. You could then make an informed judgement about it. Even Mana's detractors (people who have used it & then subsequently decided that they didn't like it after all) seem to think that it has some sort of effect on the sound. I don't have the time nor the equipment to construct any graphs about Mana, but I can hear quite clearly what effect it has had on my gear. YMMV.

Earlier on, you suggested that I should ditch my CDS2 and overpriced preamp because some cheaper items 'would sound just the same'. I didn't see any data or graphs to back up that suggestion, but I don't mind too much - it's your opinion and, fair enough, you are entitled to it.

 

Mmm , interesting comments Antonio - thanks for that.


Could you go into a little more depth regarding the comparisons you performed on mid bass integration and phase correction with suitably designed bass cabinets? I'd be really interested in your experiences here.

 

Merlin has stated that he is using his main speakers full range, my initial suspicions would be that doing so would bring all kinds of time alignment and phase issues in the critical mid-band area as the sub runs right up into the low mid. Theoretically the effect is not too dissimilar to using two different sets of speakers at the same time, and that is something that has never been seen as a good idea in serious audio. I'm not for a minute suggesting that his system doesn't work – I've never heard it, and he is in a far better position than me to judge. I just commented that it is unusual. It is!

I'm actually more curious as to why your system measures like a car boot mounted sub, and why the hell you seem to like it like that!

Tony.

 

AK,

I don't think Dat has a mind of his own, he certainly has yet to show any eveidence of it and I suspect he may find your request difficult without further reading.

WM, I'd agree on the groove point, but the volume loss is primarily down to the loss of room gain, which might well be a good thing.

The Tact setups I have heard that had big dynamics and volume capability typically used high sensitivity horns (where the room's contribution is reduced anyway) or very large amounts of power!

It would be interesting to measure your room again. There will no doubt be a reduction in the bass output, but the room gain will still be much in evidence as that remains a constant in your setup. Lucky you I say!

 

Mike,

I remember when you did Graham N's he had the same effect on his overall volume level too, have you got Graham's room plot there also?
I feel That horns do help, but again the too coloured, and the tact is about faithful reproduction, compromise there possibly?
Lots of watts, helps, but as I found with my room time domain manipulation experiance, was that fully active, was the way to go, the robbing of the volume do due indivdual driver 'controlling' was minimalised due the fact of one amp powering each pair of drivers rather than one ampilifer doing the whole lot. a much better solution, if a trifle expensive
I'm sure that excellent results could be achieved with this method.
The car subs that sounded like that, we designed specifically for those muppets into spl, where tuning the box (sealed & odd ball ported) to the natural resonance frequency of the carbody shell, using it as a 'free turbo' if you like, giving seriously enhanced volume levels at or near the right freq's required for muppetery displays.
Main culprit for that rather K2 curve' was the speakers used at the time GR 20's front ported, and the room reaction was, well 'interesting'

 

So you're getting better bass response from your current rear-ported speakers? Interesting, in that that doesn't tally with my experience - especially with concrete walls.
Have you moved the speakers further from the wall, or listen at lower volumes, or is this just a question of speaker positioning?

ps heard some Tannoy Westminster Royals today with some BLue Note (Sonny Rollins). Truely amazingly lifelike and it nailed the groove thang pretty well. I was doubly amazed to see a Teac VRDS25 and some Mark Levinson electronics powering those monsters (although I suspect pretty much anything would have sounded fabulous).

 

I thought the Meadowlarks were transmission line?