Graham Holliman Velocity Coupled Infra Bass Speaker?

I did some unscientific experimenting today with my 8" Holliman speaker... I added mass to the driver cone, increased the opening in panel "B", decreased the opening in Panel "B", added additional wings to the "exit ports", tried smaller room, and many combinations of the above, etc... I am not able to get additional output below 25hz....

Charlie

As I mentioned in post 373, changing the diameter of hole B doesn't change anything except throat velocity, it isn't going to have any effect on your fundamental frequency.

Adding weight to the driver cone isn't going to do much at all either. It takes a lot of weight to drop fs and all that's really going to do is kill the higher frequencies. The box tuning is really the boss, not driver fs.

Not sure what you mean by "additional wings" but if you made the ports longer that should definitely tune the box lower. As we mentioned earlier our best guess at your previous box tuning was 40 hz - are you saying that some of your changes resulted in flat response down to 25?

In the interest of understanding this box better here's what I am prepared to do. I will model your box as built and then simulate the changes necessary to drop the tuning to whatever you want it to be.

In exchange for that I require the following things.
1. Measured driver parameters if at all possible.
2. Measured dimensions for input into Hornresp (cross sectional areas and lengths of segments).
3. The name of the measurement program you are using and info on the mic (name, is it calibrated, etc)
4. I'd like to see you use a measurement program with no (or limited) smoothing if possible. ARTA, HolmImpulse and Room Eq Wizard are all free.
5. You need to measure it outside if at all possible.
6. I'd like to see an impedance sweep if possible.
7. You need to try to accommodate me if I come up with more demands.

Let me know if you are in.
 
I'm though a little sceptic on what material actually have much sound below 20 Hz ....... I'v done some experiments with my own sub to find out how deep you actually have to go, and I didn´t find many recordings with any sound below 25 Hz. Does any of you guys have a list of material which actually have sound that deep. And do you also have some software which can show it ..... would be cool.

There's not much music that goes lower than about 27 hz unless it's specifically manufactured to do that. There is music that goes as low as 5 hz but you have to look hard to find it.

There are a couple of good programs to analyze music, the best one is Spectrum Lab but it's terribly complicated to set up correctly. I tried and couldn't get good results without spending more time on it, which I wasn't prepared to do. But it's the one all the guys on AVS forum use. So I just Audacity. Simple to use and it does what I need.

Anyway, since a bunch of Holliman testers listed songs that work well with their boxes I analyzed a couple of them.

Here's a quote from fragma (Ryan Reynolds, the guy that built the 10 inch version and subsequently wrote "Appendix A - A Builder's Experience" in the Holliman plans document). Quotes from post 5 and 29 of this thread:

In Enya number 4, there is a sub fr undertone of around 15Hz the entire song that you cant hear on a conventional system. However, half way through the song you need to turn it down ....its too much to bear, but serves as a great demo.

In fact a particular song number 4 on Enya's watermark (ill double check that number) i can only listen to for about a minute or two before i have to fwd. It has a continuous low fr that exists throughout the song without letting up ...

Track 4 on watermark is "Storms in Africa". Here's an analysis of the song. First image is an overview of the entire song. Second image is a 1 second clip at the very beginning, third clip is a 1 second clip further along in the song. Is that low tone 30 db down that I had to actively search for what's making him sick or is it the 40 - 60 hz content? Remember, he built the 10 inch version.

An externally hosted image should be here but it was not working when we last tested it.


Another Holliman owner said this song works well - La Musique by Latex.

An externally hosted image should be here but it was not working when we last tested it.


Just in case you were wondering what real bass should look like, here's Get Low by Lil John and Eastside boys (top image) and Bass I Love You (bottom image). Get Low works well in my car stereo with it's 32 and 39 hz notes and Bass I Love You is famous for breaking subs all over the world.

An externally hosted image should be here but it was not working when we last tested it.


So you be the judge, but as far as I'm concerned, Holliman owner's aren't experiencing any REAL low bass. They aren't using tracks will real low bass to test and the tracks they do report work well have strong content in the 40 - 60 hz range. There may be some low bass in these tracks but it's 30 hz down and I doubt that's what they are hearing.
 
If you (or anyone else) is really interested in making this box with aluminum or steel panel B then I'll sim it. Otherwise there's not much point. It won't make any difference anyway, it's not going to drop the tuning.

That comment illustrates how treacherous it is to pay attention to models to the exclusion of all else.

Do you really think an enclosure made from thin steel panels sounds the same as an enclosure made from solid stuff... whatever your model may tell you?

(Actually.... to be more precise, all models have requirements and assumptions and results can be pretty meaningless when these assumptions are violated. Often, the assumptions are just assumed, rather than stated, as in "... any person knows this model assumes PERFECT rigidity of walls...." and stuff like that. Moreover, you can't expect a model to address all the fool things people might do, however numerous the stated assumptions.)

Ben
 
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The implication in my statement (that you quoted) is that it won't make much difference in the simulation. I didn't think that needed to be made any more clear.

As far as the real world difference, I'm not sure there would be much difference there either. Look at the plans. Even in the largest (15 inch version) box, panel A reinforces panel B, so the area on panel B that we are talking about is only the area of a 13.5 inch diameter circle. This area is further reduced since this 13.5 inch circle is well braced by the battens on the bottom side of panel B. The largest unreinforced distance on panel B is about 8 inches at most. How strong does it really need to be?

To get a real idea of real world distortion potential we would have to do a thorough examination of the pressures inside the box at this point in space and then evaluate the modulus of elasticity of hardboard vs aluminum/steel and compensate for the difference in thickness between 3.175 mm hardboard vs 1 mm aluminum/steel. But I think that's mostly pointless, I think it's plenty strong as it is. We're not talking about entire panels here, only a very small area of panel B where it's not reinforced from the top or bottom.

I think a much larger problem is that the plans show no bracing in the ports or compression chamber. (There are panels K which act as bracing in the chamber, but those were put there for a different purpose, proper bracing is not mentioned anywhere in the plans.) If I was going to build it I'd run a brace all the way down the length of the ports (which would also reinforce panel B even more than it already is) and add quite of bit of bracing inside the chamber.

Anyway, as I previously mentioned, I spent at least a couple of hours studying the possible "whistle" effect, which can't be fully simulated. So why are you assuming I'm "pay(ing) attention to models to the exclusion of all else"?
 
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@ just a guy

I have no plans @ the mo to build one, though i've often played with the idea of doing so on n off since i 1st discovered it. This latest kick to the thread might just inspire me to do so !

Once again, i Appreciate ALL you're doing on this :)

@ bentoronto

I wasn't suggesting that the whole box be made out of metal :D ONLY a small area just a bit larger than Panel B's hole.

*

I have a feeling that, even though this could be compared to a "standard" Reflex in some ways, it's more than that due to the pressure chamber. And consequently "may" sound different.

In the late 80's i designed a box that incorporated a hybrid type of TL loading that went down to 15Hz. I approached Arthur Bailey, yes THE Dr. Bailey who was @ Bradford University @ the time, & asked if he "might" be interested in testing etc it. To cut a long story short, i was invited over to BU for an afternoon & he ran various tests on it in their anechoic chamber etc. He was extremely impressed with how linear it responded, amongst other things. Anyway i didn't have the funds to persue it @ the time, so it went no further. But i used it @ home as a sub for years, & it produced the nicest & cleanest lowest bass i've ever heard, unlike anything else then or since. Everybody who heard it, including non techie types, but who where into various types of modern music, ALL commented without persuasion, on how good every record sounded. It had a Very special effortless grand expansive non fatiguing sound. So on that basis GH's design "might" sound special also ?
 
In the late 80's i designed a box that incorporated a hybrid type of TL loading that went down to 15Hz. I approached Arthur Bailey, yes THE Dr. Bailey who was @ Bradford University @ the time, & asked if he "might" be interested in testing etc it.
Always great to hear of inventions and tests.

An interesting thread on Karlsons taking place now... once again. Karlsons, TH, and maybe this GH design are somewhat complex designs and a bunch of factors add together to produce - on a good day - kind of flat response and good sound.

Not least seems always to be careful selection of the driver!!! Yes, I understand roughly how driver SOME parameter charge the models in important ways. But when careful selection of drivers (even with comparable important parameters) matters, I am suspicious (not pointing to the GH here, just sayin').

Most of us find it more "elegant" to have a single principle of enclosure - including non-enclosure... a perenial favourite and can't be beat for "elegance."

Yes, I like elegant solutions and always seek them. But nothing is bad when in a technology that CAN'T be satisfied elegantly today we have to use multi-resonant phase-tricking enclosures and by modeling and by luck make the bumps and dips even out.

Ben
 
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Karlsons, TH, and maybe this GH design are somewhat complex designs and a bunch of factors add together to produce - on a good day - kind of flat response and good sound.

Not least seems always to be careful selection of the driver!!! ...

... we have to use multi-resonant phase-tricking enclosures and by modeling and by luck make the bumps and dips even out.

Ben

You make it sound like there's some kind of mythical wizardry going on. You can't trick phase and it's not luck that provides flat response, it's careful attention to details and simulations.

I've seen dozens of examples where simulations almost exactly overlay measurements when the sim and the build were performed carefully and with attention to detail. In other words, if you build what you simulate the results are not going to be a mystery.

I'm going to ask again about your Klipsh horn. I've never looked at one in detail but I know it produces resonances and won't have anything even approaching flat response. So why is that acceptable while other alignments are not? Since you've never heard ANY of these alignments you are complaining about what are you basing your judgements on?

But when careful selection of drivers (even with comparable important parameters) matters, I am suspicious

Are you suggesting there is ANY type of alignment where the driver selection is not important? Or are you just suggesting that complex designs should not be attempted even if the designer knows what they are doing?
 
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Well you must want someone to ask?

@ just a guy

I have no plans @ the mo to build one, though i've often played with the idea of doing so on n off since i 1st discovered it. This latest kick to the thread might just inspire me to do so !

Once again, i Appreciate ALL you're doing on this :)

@ bentoronto

I wasn't suggesting that the whole box be made out of metal :D ONLY a small area just a bit larger than Panel B's hole.

*

I have a feeling that, even though this could be compared to a "standard" Reflex in some ways, it's more than that due to the pressure chamber. And consequently "may" sound different.

In the late 80's i designed a box that incorporated a hybrid type of TL loading that went down to 15Hz. I approached Arthur Bailey, yes THE Dr. Bailey who was @ Bradford University @ the time, & asked if he "might" be interested in testing etc it. To cut a long story short, i was invited over to BU for an afternoon & he ran various tests on it in their anechoic chamber etc. He was extremely impressed with how linear it responded, amongst other things. Anyway i didn't have the funds to persue it @ the time, so it went no further. But i used it @ home as a sub for years, & it produced the nicest & cleanest lowest bass i've ever heard, unlike anything else then or since. Everybody who heard it, including non techie types, but who where into various types of modern music, ALL commented without persuasion, on how good every record sounded. It had a Very special effortless grand expansive non fatiguing sound. So on that basis GH's design "might" sound special also ?


How about the short version of your hybrid design? Was this along the line of daline? Were you using a damped line or an open vent of length and was it an 1/8 wave line? 1/4 wave is over 16 feet long at 15 Hz. so that is on the large size. Will be interested to hear what you were doing. Best regards Moray James.
 
snip
I'm going to ask again about your Klipsh horn. I've never looked at one in detail but I know it produces resonances and won't have anything even approaching flat response. So why is that acceptable while other alignments are not?snip
No wish to hijack thread. Folded corner horns have terrible shortcomings and wonderful strengths (one of which is suitability for motional feedback control). Various other good ways to mount drivers and to make sound... esp. electrostatically*.

BTW, you seem to be using the words "alignments" to mean driver mountings and "resonances" to include all tonal variations which are your own unique meanings.

Ben
*but I have to admit shaking heavy piece of cardboard to make sound (AKA Rice-Kellogg) seems like a pretty stupid method... but also stupid is propelling cars by explosions on top of reciprocating pistons.
 
Folded corner horns have terrible shortcomings and wonderful strengths...

You could say that of all alignments but I contend that you can't judge these strengths and shortcomings until and unless you simulate and/or measure an example (or several examples) of any given alignment and then listen to them to correlate the measurable artifacts (like group delay, imperfect phase, etc) to audible traits and determine how good or bad these characteristics are.

In this case though, the presence of 60 m/s throat velocity is a huge red flag for me. Since the design doesn't sim better than a normal ported box and I see no proof whatsoever that even the largest model comes anywhere close to living up to the marketing hype, I don't feel too bad judging it prematurely.

On the other hand, I've got a tapped horn and a flh both made with the same driver. I've simulated, measured and listened to both of them. The tapped horn sounds much better than the flh despite having more group delay and less perfect phase response. But since they are made with different materials (mdf vs plywood), they were designed with different methodologies (the tapped horn is a scaled down Danley clone while the flh was designed for smoothest possible response) and they have different tuning, I can't make any sweeping generalizations about either alignment. All I can say for sure is that both of them sound better than the same driver in a ported or sealed box. But if I had several of the same driver in sealed boxes and plenty of power maybe I'd prefer sealed.

BTW, you seem to be using the words "alignments" to mean driver mountings and "resonances" to include all tonal variations which are your own unique meanings.

I'm using the word alignment to describe different ways of loading a driver. OB, IB, sealed, ported, tl, bandpass, flh, blh, tapped horn, etc are examples of different alignments. My use of the word has nothing at all to do with resonances or tonal variations.

If you don't want to hijack the thread start a new one, as I recommended a long time ago. We could discuss this at length but this is a conversation about the Holliman box. You haven't made a single comment yet specifically about the topic at hand. You've brought up the evils of resonance, phase and elegant alignments, tympanic membranes, the treachery of trusting simulations, coloration and one note bass, but all as general concepts. Not a word about the Holliman box in particular, or the info presented about this box.

BTW, electrostatic is not a way to mount a driver, it's a different type of driver that uses different technology and different parts than a moving coil driver.
 
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Infra bass

@ just a guy

I have no plans @ the mo to build one, though i've often played with the idea of doing so on n off since i 1st discovered it. This latest kick to the thread might just inspire me to do so !

Once again, i Appreciate ALL you're doing on this :)

@ bentoronto

I wasn't suggesting that the whole box be made out of metal :D ONLY a small area just a bit larger than Panel B's hole.

*

I have a feeling that, even though this could be compared to a "standard" Reflex in some ways, it's more than that due to the pressure chamber. And consequently "may" sound different.

In the late 80's i designed a box that incorporated a hybrid type of TL loading that went down to 15Hz. I approached Arthur Bailey, yes THE Dr. Bailey who was @ Bradford University @ the time, & asked if he "might" be interested in testing etc it. To cut a long story short, i was invited over to BU for an afternoon & he ran various tests on it in their anechoic chamber etc. He was extremely impressed with how linear it responded, amongst other things. Anyway i didn't have the funds to persue it @ the time, so it went no further. But i used it @ home as a sub for years, & it produced the nicest & cleanest lowest bass i've ever heard, unlike anything else then or since. Everybody who heard it, including non techie types, but who where into various types of modern music, ALL commented without persuasion, on how good every record sounded. It had a Very special effortless grand expansive non fatiguing sound. So on that basis GH's design "might" sound special also ?

Hi Zero D

What driver did you use?
 
@ darkmatter

Where have you been hiding ? ;)



It was a Richard Allan HP8B.

Been very busy with other stuff and with my Astronomy!!

How did it perform?

I have four JBL 18" Bass units

So many ideas, what to do with them and what to build!!

I am thinking of building a pair of really big TLs or a pair of Graham Holliman Velocity Coupled Infra Bass units with one set of the JBLs

The other set bass drivers will be used in conventional 450 litre cabinets, tuned low.

I am after serious bass and don't like small EQ'ed boxes

DM :D
 
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Can somebody provide a summary, coherent rationale, or otherwise help with an introduction to this speaker, please.

I found one write-up on the web from an engineer from South Africa long ago that has no small amount of audio-babble and special pleadings that would give anybody but "true believers" serious doubts.

The concept seems to have sunk without leaving a trace on the web (except here, bless us).

B.
 
What to build next

As i mentioned earlier, & in your Post #415 ;)

I hope you get to build it, & soon if you're not too busy :D Let us know how it's proceeding etc etc, with pics :) All the best with it

Thanks for that, still not sure what to build next, but I want to learn more about the mathematics behind the Holliman speaker first.

I meant to ask you about the TL, not how it performed, but about the cabinet, as I wanted to up-size it to suit my 18" JBL!! It doesn't matter if it ends up huge, it is how it sounds that counts, and will be more than happy if I get a real nice 12Hz or so!!

ATB

DM :)