homebuilder wrote:

I am new to this interesting site, and am hopeful of getting some assistance with a project.  I have purchased a set of TAD 1201 mid-bass drivers to begin a 4-way active system for critical home listening.  (in a dedicated room, 21' x 25' with peaked seilings at 11.5')  I already have the balanced x-over, and tube and solid state amps. I plan on either the JBL 2226H or 2241H for the bass, and the 2404H for the treble. My problem lies in the midrange.  I'd like to use the 2344a horns with 2426 drivers, but cannot locate any of the horns.  Any help there?  Or, I have considered using either one, or a pair of large cone midranges, such as the JBL 2012H.  Is it practical to use large drivers such as the 2012 in an MTM arrangement? The cabinet will be built of HDF, and will be multiple layers laminated on top of each other. It will be nearly round. Very heavy, massively braced.  I have friends with a CNC router, so that is a huge help. Does anyone have any suggestions for the midrange? Other horn combinations?

So, it will be:

2241H for the LF
2404H for HF
TAD 1201 for mid-bass
MF channel

….the 4-way system. What kind enclosures are you intend to use? The 2241H is a ported-type driver, with somehow pro-like bass. Thos pro drivers are better in midbass then in lower bass. The 2404H is high-power SS-require tweeter, something suggests me that it might not be your finals chose if you consider “critical home listening”. TAD 1201 is a “terra incognito” for me but it looks like a very interesting driver. Still it is unknown how you will be using then: horn of boxed. If your go for no-horn-loaded MF and they all will be boxed then you might consider symmetrical double driver configuration with a tweeter in a middle and then two MF driver, two midbass drivers and two woofers.  As MF might be anything you like, but I would start with JBL L8. I hope your rest of the driver will be able to keep up with L8’s tone (and you should not wary about the sensitivity as it will be active anyhow). You might consider even to put MF in open baffle in that case… If you go for TAD 1201 in horn then it would be a different game and you might look for a compression driver for MF.

I generally am very uncomfortable with recommendations unless a lot of specifics in play. At this point I do not feel that you have a clear and defined vision what you are trying to build. I might advise you to do what I always do - starting to talk with your driver that you already have. Connect your TAD 1201 to the amp that you know and play it full-range for a while. Use different music, learn how the driver reacts to damping, reacts to volume, reacts to crossover and etc, etc, etc… You need to get a feeling where are the strong and week moment in a given driver and then come up with an enclosure that will accent the driver best qualities and shadow out the driver weak qualities.  Pay particular attention to the diver upper range as wherever you feel it will “slip” you would need to introduce a MF driver. Then, when you will try the MF driver you would need to look for the midbass and midrange driver TTH compatibility…

I call this approach a “Derivative Design” and it is the only approach in my view how an acoustic system might be planed. I have writhe about is many times. This method organically includes the person understanding of sound and the ability of acoustic system to present sound… The problem with this apprise that it takes time…

el`Ol wrote:

JBL developed the PT-Waveguides not only because they are easier to produce. They also have less harmonic distortion than biradial horns. Disadvantage: They look far less funky.

Greg, I see a regions of concerns that you might contemplate.

TAD 1201 might be good driver but how useable would be the 200/300-800/1000 range? Let pretend that you end up with 250Hz, then what next? You will introduce a bottom octave section but to cover a range from the very begging to 250Hz is practically impossible with one driver. To reproduce 30Hz and 250Hz is require VERY different type of drivers otherwise it will be a compromise in one of other extremes.  In your room of 21’ by 25’ I would like to see driver with Fs of 20Hz in 25-30 enclosure – those types of the drivers will never go up to 250Hz. In a contrary if you go for 35Hz bass drivers (typical JBL) in 45Hz enclosure then in your room you will not get the lowest octave. BTW, did you consider to EQ down the TAD 1201 with a horn? It is 52 Hz driver and in a horn you might easily to push the driver to down to 100Hz or even lower. Do not forget that horn wills EQ the driver + it will have add a few dB at LF that will minimize the excursion…. They are 12-inchers so, 7-8” throe would do most likely…  Though I have to warn you that I am generally horns-biased… What I mean was that if you already have 4 of those 1201 drivers (you intended to use then in MTM configuration) and if you found them “amazing” then it might be a plausible direction:

homebuilder wrote:

...active EQ will be a part of this project, along with in room measurement. My friend will do the honors on that. I have not purchased an EQ yet.

You might eventually revise your view about the active EQ and presumably crossovering. If you go for an active system (will have) then you do have 4 amps and therefore I see no needs for active EQ. The necessary for you EQ and crossovering might be done passively at line level. You might buy or borrow an active unit, perhaps digital unit to plat with it but after you defend the necessary slopes and cut offs than you can replace the active unit with fixe line-level filter for each power amplifier. With EQ is the same but it all depending: for what you will be using your EQ. I hope you will not correct with it your room problems… If you need EQ to push a little the edge of one of other channel then it is fine (as lond as the filter was not closed in this channel) and you might do it very easily at line level.

homebuilder wrote:

.… On your idea of horn loading the TAD:  how critical is the shape of the horn? I've seen billions of ideas, but don't know where to start.  If we horn loaded the 1201, would we not also need to do the same with the bass driver?  Or would your 25-30 (cf?) do the trick?  I assume that is ported?

Well, I personally do not accept any ported enclosures, but it is me. The horn for 1201? I really do not know. I never saw or heard this driver. It would be too brutal to advise you to experiment with it yourself. Try to found some your local guys where you would be able to listen some upperbass horns and to try your drivers in some kind of horns. In your part of the country you might have difficulties to find anyone horns-civilized. You are from Iowa if I am not mistaken. Indians should be somewhere near you, one state over. Try getting in touch with John Hasquin, he was semi-retired few years back unit his wife finish her school be you might wake him up. Right across Missouri will be Tennessee. In there, in Memphis there is Jeffrey Jackson. I did not see or hear his speakers but he had popped up a few time at this forum and in conversation about horns he sounded surprisingly inelegant. I said surprisingly because you might discover that many people who talk about horns should not be doing it. So, perhaps Jeffrey or John deal with those drivers and they might inspire your to look into a horn direction or might introduce you with their local customers where you might get familiar with upperbass horn opportunities. To design the final horn for that driver is very-very simple task but you would need some kind of prototype horn to learn about the Sound of this diver horn-loaded.

homebuilder wrote:

Do you have any experience with drivers of this type in OB configuration?  What is to be expected?

Wojtek wrote:

Roman, could you (or enybody ) elaborate a little bit on JBL L8 and its application ? Not so much sensible info on the net besides that its a fullrange usefull in 40Hz-8kHz.

Wojtek wrote:

I have a pair of JBL Lancer 33 speakers -~1.5 ported with single LE8 with recently changed surrounds which have not been played for a long, long time.

Wojtek wrote:

" The only concern being that ML2 is a feedback amp and Mel not.

Greg,

BTW, if you go for direct radiation and would like to go for Dunlavy-like symmetric configuration (perfect for along wall) then here is for you an idea that I do like very much. I took that idea from old version Kharma Audiocritique and made it more swallowable-visually. This year the Evolution Acoustics MMthree did (shape-wise) almost exactly what I envisioned: water-dropped Dunlavy. I LOVE this design and if I live in a world of direct radiators then I would do something like that. Add to the speaker one more layer of upper bass drivers - making it MMfour and use the real MF drivers (not the ceramic crap as the Evolution Audio uses) and it would be it. 

I do not have lot of experience with TAD cone drivers but there is a thing bout then that always afraid.

A few years ago I was at demonstration of Model-1, the TAD’s $50,000 flagman model and it had very strange feeling – the speakers sounded surprisingly pleasant but at a certain dynamic level everything stopped. It was some kind of threshold compression and further then that abstract “dead point” nothing was able to move: dynamic, tone … everything was literally stopped there.

I still have no ides what it was – perhaps it was not the TAD drivers, but I never seen this effect so strong in any other speaker. I spoke with the designer and learned that the Model-1 did not use standard drivers but custom made by TAD drivers. When I sled him about the “threshold compression” he began to express doubts that I am in a sane mind as he thought that that sound he was presented is flawless. I left him alone as I generally avoid people who have no capacity of critical thinking about sound or can not effort the critical thinking.

The negatives outflow was that I still do not know what it was in case of the TAD’s demonstration. Was it the crossover, the divers or the electronics that introduced the “threshold” – it is unknown to me. Still, if I touch the TAD cone drivers I would test them for the presence of the “brickwall effect”

Announced for some time, finally out:
http://www.eighteensound.it/index.aspx?mainMenu=view_product&pid=264

I didn´t have a chance to listen, but I am very interested in the lower cost polyethylene drivers. When I first read this I thought it is a joke. I wonder how that sounds.
Seems that in home audio the horns are currently more popular than the drivers. I am currently thinking about a fun project with them: Take some pairs of NOS B.I.C Venturi drivers from the seventies, combine them with the smallest Eighteensound horns, take these seventies style orange cubes as enclosures that are currently modern again (two way speakers) and sell them off at Ebay (in the furniture section). Not for earning money, I am just interested whether there is a demand for something like that.

For normal (even pro) use I find the 6.5"er more interesting than the 8"er:
http://www.eighteensound.it/index.aspx?mainMenu=view_product&pid=244
I just thought 31Tm for a midranger, that´s sick.

I never seen the polyethylene drivers but I would not say that it would be a joke, I would rather say that I have no idea what to expect. The SL600 MF driver is a polyethylene-like driver and it does have some interesting qualities, Sure it you drive it under 120Hz then the SL600 MF driver begin to sound like shopping back trembling from wind gust but above it does very nice. There is another consideration why I would not consider a polyethylene driver as a joke. With my horno-snobbery I hardly see a driver as a potential direct radiator but I see them only a candidate to be horn-loaded. There are absolutely no rules of prediction what will happen with sound when a driver is horn-loaded. You can put a farting porcupine in the throat of a horn and it is suddenly might throw a good tome out of horn, I have seen it, so go figure…

Regarding the Eighteensound 6.5"driver – it looks good, however I have some concerns. You see, the Eighteensound driver is a pro driver that made for higher power handling – it is never good and there are a lot of reasons why. There is another aspect. Those drivers have the cone treatment that makes the cone suitable to work outdoor in moisture weather conditions. Usually it is done with different propriety treatments; all of them impregnated rubber-like minerals into the body of the cones. Those rubber-like deposits are not good for sound as they overly dump the cones… There is a catch however. If you buy 30-40 years old Altec, JBL, Vitavox and so on cone drivers, that mostly had the similar impregnation then the rubber-like mineral are faded away and become less contributive. Those “dried out” drivers as VERY sensitive to moisture outside but they do have way better tone then the “new” cones.  I made some experiments in past, comparing the 30 years in air good cone driver and reckoning then with identical original come that was sitting for 30 year in a sealed plastic back – the difference was VERY notable. You do not need to listen the driver and can juts scratch them with you nail – you will immediately feel the “dryness” of the cone…