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Any reason NOT to do a THT? - Page 6

post #151 of 211
Not sure which part you are unhappy with, but I suspect it's this:
Quote:
If you don't understand these issues and don't know how to simulate it's easy to ignore this data in favor of marketing claims but most advanced members here will agree that simulation is a very powerful tool.

I wasn't talking about you specifically, let's change that to "If people don't understand these issues...

Asking where your measurements are is a legitimate question. Have you simulated or measured this design? If you haven't it's probably for the same reasons most other people haven't. It truly would be nice to see some accurate 3rd party high power performance measurements taken outside in an acoustically appropriate environment.

Nothing else in that post could possibly be considered axe grinding.

As far as everything else I've posted, if you can find ANYTHING that isn't true I'll happily delete or correct it.
Edited by diy speaker guy - 8/29/13 at 3:56pm
post #152 of 211
Quote:
Originally Posted by koturban View Post

I asked an honest question. Your retort was unnecessary and unwelcome.
Your axe-grinding is tiresome.
+1. And who is this 'DIY speaker guy' anyway? His personal profile is empty, and if he's ever designed a speaker himself I can't find one listed. He seems to know his stuff, enough so that I suspect he's a sock puppet of someone who has a personal gain in talking down Bill and his work. Too bad he didn't bow out of this thread all those pages ago when he said he was out. If he had he might have some credibility, but now he has none.
OP, I have two THTs, love them, along with my TLAH and SLAs. And you should have gone to Bill's forum in the first place.
post #153 of 211
Quote:
Originally Posted by jkkwaz View Post

Well I am definitely going to be doing some measurements... I taught myself how to use REW last night and had fun with that. I used my rat Shack microphone, probably not the best method, but hey, it works. Would I be better off using the calibration mic that came with my Denon I wonder?
If you are referring to a RS SPL meter -they have weighed response and the Denon would be more accurate.
( I'd have to see the Denon calibration file )

Now you'll excuse me for dropping out - but it looks like this thread is going nasty
mad.gif
post #154 of 211
Thread Starter 
Thanks, WVSyd, and I agree
post #155 of 211
Among others here, I've measured a THT. No surprises found there. It worked as expected.



The dip was due to placement, but the important parts of the curve are all present and accounted for.

Those SPL numbers are reasonably accurate, 2.00 V drive, measured at a meter, groundplane.

I've also simulated, designed, built, measured, and shared a lot more stuff, objectively.
post #156 of 211
Quote:
Originally Posted by diy speaker guy View Post

Not sure which part you are unhappy with, but I suspect it's this:
I wasn't talking about you specifically, let's change that to "If people don't understand these issues...

Asking where your measurements are is a legitimate question. Have you simulated or measured this design? If you haven't it's probably for the same reasons most other people haven't. It truly would be nice to see some accurate 3rd party high power performance measurements taken outside in an acoustically appropriate environment.

Nothing else in that post could possibly be considered axe grinding.

As far as everything else I've posted, if you can find ANYTHING that isn't true I'll happily delete or correct it.

You were talking to me specifically when you retorted "where's your measurements?".

Attacking my credibility and further axe-grinding simulations doesn't answer my question.

A simple "yes" (with a helpful link) or 'no" would have been sufficient.
post #157 of 211
Quote:
Originally Posted by RickJames View Post

+1. And who is this 'DIY speaker guy' anyway? His personal profile is empty, and if he's ever designed a speaker himself I can't find one listed. He seems to know his stuff, enough so that I suspect he's a sock puppet of someone who has a personal gain in talking down Bill and his work. Too bad he didn't bow out of this thread all those pages ago when he said he was out. If he had he might have some credibility, but now he has none.
OP, I have two THTs, love them, along with my TLAH and SLAs. And you should have gone to Bill's forum in the first place.

I have a long history (probably about 7 years) at diyaudio.com (different user name there). I have a shorter history (probably about 3 years) at techtalk.parts-express.com. I already admitted I have a personal history with Bill (probably about 2 years) in which he enjoys destroying my informational threads on horn design and construction (not on this forum). I also have a history of pointing out inaccuracies in specs and claims with different companies. As you can imagine this does not make me popular (especially with people with financial and emotional investments in these products) but I've exposed some spectacularly fraudulent claims over the years from several different companies. I'm not on the internet to make friends, I'm here to collect and share ACCURATE information.

As little as 8 years ago I had no technical knowledge of anything audio related. I have no financial stake in the audio industry in any way and I am not interested in being financially involved. I have no affiliation whatsoever with anyone who sells anything or would profit in any way from anything I say. This is just a hobby for me. I have designed, built and measured all types of things, including front loaded horns and tapped horns but mostly for personal education purposes, not public consumption. I can assure you I am not a sockpuppet but it's funny that you accuse me of sockpuppeting in this conversation, anyone hanging around diyaudio around 2006 or so will know how incredibly ironic this truly is.

I have nothing to hide. Email me and I'll give you my real name and life story if you want it.

But you are right about one thing. There's no point in talking about his anymore, the issue has been thoroughly covered.

Have fun, guys.
Edited by diy speaker guy - 8/29/13 at 5:30pm
post #158 of 211
Quote:
Originally Posted by diy speaker guy View Post

I have a long history (probably about 7 years) at diyaudio.com (different user name there).
That explains a lot. I've lurked there maybe three or four times, and all they do there is argue. Places like that give the internet a bad name.
Quote:
I have a personal history with Bill (probably about 2 years) in which he enjoys destroying my informational threads on horn design and construction (not on this forum).
So you're out to even the score? That's about as petty as it gets. I've never seen Bill destoy any threads that gave accurate advice, so could it be that you were just plain wrong? Naw, that's not possible, not with 7 whole years of experience. biggrin.gif

Edit: I looked around at the PE forum. I found a few threads where Bill offered you nothing but constructive advise, and you rejected it as if he was the noob and you were the expert with 40 years experience. He wasn't the only established expert there to suffer the same fate when they tried to help you. And in more than a few threads you later went back and deleted all your posts, really, really childish. But considering how much you've dissed the OP in this thread you should do the same here.
Edited by RickJames - 8/30/13 at 9:00am
post #159 of 211
Quote:
Originally Posted by jkkwaz View Post

Thanks, WVSyd, and I agree
You are welcome.
And I'll extend an offer to converse in private if need be.

I figured you did not want this thread to be an exchange of illogical arguments.
I could corroborate what has been said; I was on the aforementioned forums since 2006.
And discuss my experience.
And I would do so to anyone ( in private )
Ad Hominem attacks ruin discussion.
Edited by WVSyd - 8/30/13 at 11:29am
post #160 of 211
Moderator

what goes on at another forum can stay there

please limit posts on AVS to technical issues

Thanks
post #161 of 211
I like and appreciate what DIY G has to say, offer, and opinions abuot technical designs but with a little hmmm what's the word, .....
post #162 of 211
Quote:
Originally Posted by jkkwaz View Post

Thanks, WVSyd, and I agree

lol... maybe start another thread when you get build pics up biggrin.gif
post #163 of 211
Quote:
Originally Posted by diy speaker guy View Post

Nothing else in that post could possibly be considered axe grinding.
+1

DSG has been one of the best contributors to this thread and has provided valuable & objective information. I really don't see how anyone could be upset or offended by anything he posted. Big thumbs-up here.
post #164 of 211
Quote:
Originally Posted by martinq View Post

+1

DSG has been one of the best contributors to this thread and has provided valuable & objective information. I really don't see how anyone could be upset or offended by anything he posted. Big thumbs-up here.
Agreed.
Anthony, Mike and John have acted with decorum.
It is often human nature for fans to perceive analysis as attack and feel motivated to defend the designer.
Objective Scientific analysis and peer review is done logically on the merits of the design and methodology - without regard to the person.
Symposiums and Seminars would collapse in chaos if irrelevance, illogical arguments and personal attacks were allowed.
post #165 of 211
Quote:
Originally Posted by RickJames View Post

+1. And who is this 'DIY speaker guy' anyway? His personal profile is empty, and if he's ever designed a speaker himself I can't find one listed. He seems to know his stuff, enough so that I suspect he's a sock puppet of someone who has a personal gain in talking down Bill and his work. Too bad he didn't bow out of this thread all those pages ago when he said he was out. If he had he might have some credibility, but now he has none.
OP, I have two THTs, love them, along with my TLAH and SLAs. And you should have gone to Bill's forum in the first place.

This coming from someone with 16 posts is laughable. DSG contributes a good amount of useful information and then you bring this rubbish? Get off Bill's dick. The S in AVS stands for Science. If you can't handle factual discussion with evidence to back it up, this clearly is not the forum for you.

That said, nobody here is bashing the THT. It does the job its designed for fairly well. We've already listed the pitfalls. If you want to pretend your THT can run flat to 10hz and at high levels without a HPF forever, keep your delusions to yourself. The collective knowledge and experience with THTs in this thread far dwarfs yours. Move along.

Quote:
Originally Posted by martinq View Post

+1

DSG has been one of the best contributors to this thread and has provided valuable & objective information. I really don't see how anyone could be upset or offended by anything he posted. Big thumbs-up here.

Agreed.
post #166 of 211
Quote:
Originally Posted by notnyt View Post

This coming from someone with 16 posts is laughable. DSG contributes a good amount of useful information and then you bring this rubbish? Get off Bill's dick. The S in AVS stands for Science. If you can't handle factual discussion with evidence to back it up, this clearly is not the forum for you.

That said, nobody here is bashing the THT. It does the job its designed for fairly well. We've already listed the pitfalls. If you want to pretend your THT can run flat to 10hz and at high levels without a HPF forever, keep your delusions to yourself. The collective knowledge and experience with THTs in this thread far dwarfs yours. Move along.
Agreed.

You see what you want to see.
post #167 of 211
Quote:
Originally Posted by koturban View Post

You see what you want to see.
+1. I don't post much, because I'm 110% satisfied with my full BFM system and don't have any intention of replacing it, unless he comes out with something better.
Quote:
DSG has been one of the best contributors to this thread and has provided valuable & objective information. I really don't see how anyone could be upset or offended by anything he posted.
This thread should have put all questions about the THT to rest four years ago. Note the measured response charts, which DSG clamored for, and could have found if he wanted to. So could you.
http://www.avsforum.com/t/1194093/myns-tuba-ht-review-llt-vs-tht

But just in case:
post #168 of 211
"This thread should have put all questions about the THT to rest four years ago. Note the measured response charts, which DSG clamored for, and could have found if he wanted to. So could you.
http://www.avsforum.com/t/1194093/myns-tuba-ht-review-llt-vs-tht
But just in case:"

it is just that kind of post that confuses the whole issue. the people who all know, know that isn't what a horn response looks like. then the people who don't know get all confused because "it is a measurement, right?"
post #169 of 211
Quote:
Originally Posted by RickJames View Post



But just in case:

I got similar readings with my horn when I had the windows open in my house. Usually many other readings can be taken to verify the validity of one like this. In my case, most readings would be very inconsistent.
post #170 of 211
Quote:
Originally Posted by RickJames View Post

This thread should have put all questions about the THT to rest four years ago. Note the measured response charts, which DSG clamored for, and could have found if he wanted to. So could you.
http://www.avsforum.com/t/1194093/myns-tuba-ht-review-llt-vs-tht

I'm aware of that measurement, I actually linked to it (the same measurement was posted in the tuba-ht-tht-compromises-trade-offs thread which I linked to) in post 87, 8 days ago. I actually talked about it a bit too at that time.
post 87 - http://www.avsforum.com/t/1484963/any-reason-not-to-do-a-tht/60#post_23661740

That measurement might be of limited usefulness to the person that measured it but it's completely useless to anyone else. There's no details about the measurement conditions except that it's an in room measurement, which is useless except for studying it in the room it was measured in. There's no indication of power level, no indication that it's a calibrated mic or even that it's a good mic at all, and the graph deviations are 30 db. The entire low end is swamped in noise and uncalibrated mic fantasy but even so it's down at least 20 db by 10 hz.

Koturban asked for COMPARISONS between the tht and ???. So I did a quick search and couldn't find a single measurement of the tht that was taken in a competent manner in an acoustically appropriate environment. Fortunately lilmike provided a measurement in post 155. Lilmike is extremely qualified to perform accurate measurements and as far as I know he does have access to an acoustically appropriate environment so there's no reason not to trust his measurement. And that measurement looks reasonably close to the simulation I've been posting, which shouldn't be any surprise, simulations are very powerful predictions.

Unfortunately lilmike didn't post any high power measurements, that's the only useful type of measurements for comparing different designs (unless you are only interested in comparing frequency response). Below is a picture of a different horn from data-bass.com (posted here because I don't think I can link directly to this graph) that shows how to properly measure high power performance. Keep turning up the power until you reach the excursion or thermal limits of the driver and start to see noticable compression.



This is what you need to do comparisons against other designs. I couldn't find anything like this for the tht, so I listed a bunch of reasons that it might be difficult to find them.

Do you actually want to have a technical conversation? As per the moderator's wishes I'm not going to address anything you've said except technical issues. If you do want a serious chat, let's go. Horns are one of my favorite topics and I can talk all day. If not then quit poking me. I already agreed to stop posting in this thread. Quit poking if you don't want me to come back.
Edited by diy speaker guy - 8/31/13 at 5:33pm
post #171 of 211
Quote:
Originally Posted by RickJames View Post

+1. I don't post much, because I'm 110% satisfied with my full BFM system and don't have any intention of replacing it, unless he comes out with something better.
This thread should have put all questions about the THT to rest four years ago. Note the measured response charts, which DSG clamored for, and could have found if he wanted to. So could you.
http://www.avsforum.com/t/1194093/myns-tuba-ht-review-llt-vs-tht

But just in case:

The fact that you're even referencing this graph proves you lack the understanding to participate in discussions even at this level.

The range on that graph is 210db wide. Even Myn has said that graph is bs. It's also smoothed. The reading at 10hz is down 20db from 23hz, and below that the noise floor is clearly being hit. I've posted measurements of THTs, where are yours? Feel free to contribute science or regurgitate nonsense, the choice is yours.
post #172 of 211
Quote:
Originally Posted by LTD02 View Post

"it is just that kind of post that confuses the whole issue. the people who all know, know that isn't what a horn response looks like. then the people who don't know get all confused because "it is a measurement, right?"
Agreed. An understanding of Acoustics, SPL and excursion will discount that graph as worthless.
To do relevant research a background knowledge of the subject is necessary.
As is the case with data collection. If one doesn't know enough about the subject at hand to insure the data gathered is reasonable and know to discount erroneous or contaminating data then it's a worthless exercise.
G.I.G.O. applies to this as well
post #173 of 211
what 'not is saying is that if you put the plot on a more reasonable scale, it will look quite different.

here is the middle 60db worth of that plot and the 2pi hornresp model overlayed. looks like he has some suckouts at 30hz and 60hz. the peak at 80hz is lower because of the crossover and the stuff down below 15hz is probably just calibration/measurement junk.

looks like the way he had it firing lowered the bottom corner by a few hz. that might be something actually worth discussing. :-)

post #174 of 211
I hadn't noticed the magnitude that scale, it is a pretty random shot in the dark...
post #175 of 211
Quote:
Originally Posted by LTD02 View Post

here is the middle 60db worth of that plot and the 2pi hornresp model overlayed...

looks like the way he had it firing lowered the bottom corner by a few hz. that might be something actually worth discussing.

Actually the low peak in that measurement lines up pretty well with lilmike's measurement, they both look like they are right around 23 hz.

The sim you overlaid was Bill's sim, no?

I've got an idea what might be causing the difference in low corner between the sim and the measurement. I see this all the time where the measured horn is tuned just a bit lower than the sim predicted. This is a common beginner folding mistake for people that don't understand the implications of folding. During the horn folding process, if the centerline method is used and length is not adjusted around the bends, the horn will end up tuned a bit lower than expected (assuming reflectors are not used in the bends). I can't GUARANTEE this is the cause of the discrepancy in this case but it seems the most logical culprit at this point, given the limited amount of data.

Bill uses the centerline method for horn folding and he is aware that this will provide a slightly lower tuning in the finished folded horn than the model suggests. Bill and I have discussed this much and disagree on the best way to fold.

I assume he just mentally adjusts for a slightly lower tuning in the finished folded horn than the sim shows. This approach is a bit odd now that the advanced centerline method is well defined and well known, but it is acceptable if you know what to expect. But you have to be prepared to mentally extrapolate (in other words make an educated guess) for ALL the simulated graphs, the simulated tuning will be a bit high, the simulated excursion will be a bit low, etc. If you use the advanced centerline folding method you don't have to do any of that, the sim is just accurate as it is.
Edited by diy speaker guy - 8/31/13 at 10:09pm
post #176 of 211
"The sim you overlaid was Bill's sim, no?"

somebody took a picture of a tht that was half built and i guesstimated the dimensions (using the simple centerline method) from that and used the dvc385 driver.

in hindsight the 180 degree bends probably cause the small shift in tuning...the same way that ports have been observed to do the same thing in ported enclosures.
post #177 of 211
Quote:
Originally Posted by LTD02 View Post

"The sim you overlaid was Bill's sim, no?"

somebody took a picture of a tht that was half built and i guesstimated the dimensions (using the simple centerline method) from that and used the dvc385 driver.

in hindsight the 180 degree bends probably cause the small shift in tuning...the same way that ports have been observed to do the same thing in ported enclosures.

Ok, well your sim is close enough to Bill's that I thought it was his. And yeah, I think it's the folding (centerline method) that's accountable for the difference between the sims and the measurements. Not just the 180 bends though, all the bends.
post #178 of 211
i kind of doubt that the small differences in size of the horn as it expands around a bend using centerline or no centerline are a significant contributor to the mismatch. the bend itself, particularly the 180 degree bends are, my guess, an order of magnitude or more significant contributor, but i don't have any good data to validate that guess.
post #179 of 211
Quote:
Originally Posted by LTD02 View Post

i kind of doubt that the small differences in size of the horn as it expands around a bend using centerline or no centerline are a significant contributor to the mismatch. the bend itself, particularly the 180 degree bends are, my guess, an order of magnitude or more significant contributor, but i don't have any good data to validate that guess.

There are a lot of bends in the tht, so using the centerline vs advanced centerline method will made a very noticable difference, easily accounting for the couple hz differences we are seeing between the measurements and the sims.

Soho54 spent a LOT of time simulating horns and correlating them to measurements and this is the method he found that worked.

Here's a link for those that don't know what the advanced centerline method is, post 13 - http://www.diyaudio.com/forums/subwoofers/171747-spreadsheet-folded-horn-layouts-2.html#post2270926
And don't forget to check post 35 in that same thread as the OP admits that this method does indeed give the closest correlation to the measurement after trying the different methods.

FWIW here's Bill's comments on this:
Quote:
The centerline method is accurate if a reflector is used. If not the apparent horn length will be longer because the mass of the air in the corner adds to the mass of the air in the horn path proper.

Danley suggests there's a bit more to it than that in the Labhorn notes:
Quote:
...in folding your horns...

What one cannot do is significantly change the total cubic volume of the interior, air is after all this curious combination of spring and mass and a "connectedness" to the outside. In making a bend, a common mistake is to assume the bend is longer than it really is. Going by a cubic volume alone is close but also in a bend, the air is moving in an arc and so temporarily has slightly more mass (as the bulk of the volume is on the outer half of the radius of motion).

Personally, I use the advanced centerline method for bends where there are no corner reflectors. I use the centerline method in bends where there are corner reflectors. This has worked out quite well for me since I usually use VERY few corner reflectors in my designs. I've never simulated, built and measured a design that uses reflectors in EVERY corner like the Labhorn, but in that case, Danley seems to be suggesting that something in between the centerline and advanced centerline method might be best, since due to rotational mass the centerline method might be a bit off even when corner reflectors are used.
Edited by diy speaker guy - 9/1/13 at 8:42am
post #180 of 211
i hear what you are saying... it just strikes me that the difference in the path length from the centerline to the advanced centerline method is not nearly as significant as the turbulence and flow interruption from the bends in the horn particularly the 180 degree bends.
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