I just aquired a pair of TAD 4001 drivers, and have recently been involved in some threads discussing a possible setup. Yesterday, i stumbled across a page that really caught my attention.. Sierra Brooks manufactures a line of mahogany tractrix horns, very good looking indeed, and very expensive ofcourse, but what I found especially interresting was the DIY-projects section of the site. They show a number of setups using the TAD 4001 driver, but each and every one of them utilizes one of their largest horns, a 140hz tractrix horn as shown below (the big one, mated with two Onken tweeters):
So this makes me think.. as I'm using affordable diaphragms from Radian (aluminium) much more rigid than the fragile and expensive beryllium ones, I am not too afraid of blowing them although I would rather not... Radian's datasheet on the phragms indicates a 600Hz XO with 18dB/oct slope, but says nothing about power handling at this XO config...
My question is if these drivers are usable below 600Hz, and down to what point, assuming a maximum power handling of 1 watt only, and active 24dB/oct XO slopes? These japanese guys don't use 140Hz tractrix horns just for the fun of it, do they?
An externally hosted image should be here but it was not working when we last tested it.
So this makes me think.. as I'm using affordable diaphragms from Radian (aluminium) much more rigid than the fragile and expensive beryllium ones, I am not too afraid of blowing them although I would rather not... Radian's datasheet on the phragms indicates a 600Hz XO with 18dB/oct slope, but says nothing about power handling at this XO config...
My question is if these drivers are usable below 600Hz, and down to what point, assuming a maximum power handling of 1 watt only, and active 24dB/oct XO slopes? These japanese guys don't use 140Hz tractrix horns just for the fun of it, do they?
Well, where I don't have the direct experience going that low with the 4001's, I did mke a couple phone calls.
The word from Radian is "absolutely not to be run below 500Hz."
My other conversation was with Paul Butterfield Audio (blues musician's cousin) who services TAD drivers. He has heard of the 4001's being used down to ~250Hz, but no direct experience that low.
The word from Radian is "absolutely not to be run below 500Hz."
My other conversation was with Paul Butterfield Audio (blues musician's cousin) who services TAD drivers. He has heard of the 4001's being used down to ~250Hz, but no direct experience that low.
Thanks Rodd. Interresting indeed.
I suspect that I will not endanger the Radian diaphragms when using them in configs where the original diaphragms work successfully, as they are supposed to take alot more beating than the originals... What might be an issue is rise of distortion near Fs.. I dunno if Radian's diaphragms exhibits more resonance distortion than the original TAD diaphragms, and therefore might be unsuited for a low XO?
I'll contact Sierra Brooks and gather available info on their TAD 4001 setups... like XO points, slopes, power handling, etc. I'll return with more info when they respond.
It is possible they do a low order XO at a somewhat high frequency, but gets the most out of the attenuated response down to 100-200Hz by hornloading it I guess.. It would make some sense..
I suspect that I will not endanger the Radian diaphragms when using them in configs where the original diaphragms work successfully, as they are supposed to take alot more beating than the originals... What might be an issue is rise of distortion near Fs.. I dunno if Radian's diaphragms exhibits more resonance distortion than the original TAD diaphragms, and therefore might be unsuited for a low XO?
I'll contact Sierra Brooks and gather available info on their TAD 4001 setups... like XO points, slopes, power handling, etc. I'll return with more info when they respond.
It is possible they do a low order XO at a somewhat high frequency, but gets the most out of the attenuated response down to 100-200Hz by hornloading it I guess.. It would make some sense..
If you work from the Radian Spec Sheet for the 4001/2 diaphragm, it is capable of 128db @ 60W input @ 1kHz. If we lower the frequency 2 octaves to 250Hz, we would need 4X the excursion for the same SPL (actually acoustic power). Now at 250Hz, if we lower the excursion back to XMaz (assuming it was excursion limited in the first place), we will lose 12db of acoustic power leaving us with 116db SPL. But this is not entirely accurate because SPL is not directly proportional to acoustic power. The difference is in the sound field the acoustic power is radiating into. If we assume a controlled dispersion at 1kHz equivlent to 1/16 space and a relatively uncontrolled dispersion at 250Hz of 1/2 space, we will lose about 9db more to the wider dispersion at the lower frequency. This leaves us with 105db at 250Hz @ 60W input. All this assumes that the driver has the same loading throughout the BW and into the stop band, and that it can take 60W at 250Hz.
Two things are apparent (to me), one: you're not going to get the SPLs with a flea powered SET, and two: you probably will never get to 140Hz at that SPL.
Two things are apparent (to me), one: you're not going to get the SPLs with a flea powered SET, and two: you probably will never get to 140Hz at that SPL.
Rodd, your posts are most useful, you are really a great help for me on this.. Thanks.
250Hz would be a very nice XO point, as it'll cover almost the entire voice area. Although I am building 425Hz tractrix horns already, I will build a single bigger horn when I get the calculations done, and try to use the TADs in 2 stages of a 4-way.. lower and upper mids.. Mono setup.
I can run the upper TAD on El-Spuddo (1W) to start with, but I understand I will need more power if it should be possible to run the second TAD as deep as 250Hz. My setup will be for modest listening levels, so based on your calculations I figure I'll need a power handling of 15 watts at 250Hz to reach 99dB, I need to find out if radian provides such a power handling then....
250Hz would be a very nice XO point, as it'll cover almost the entire voice area. Although I am building 425Hz tractrix horns already, I will build a single bigger horn when I get the calculations done, and try to use the TADs in 2 stages of a 4-way.. lower and upper mids.. Mono setup.
I can run the upper TAD on El-Spuddo (1W) to start with, but I understand I will need more power if it should be possible to run the second TAD as deep as 250Hz. My setup will be for modest listening levels, so based on your calculations I figure I'll need a power handling of 15 watts at 250Hz to reach 99dB, I need to find out if radian provides such a power handling then....
They claim to use 1st order passive crossover at 300Hz, on a 140Hz horn, with great results... Any comments on this?
I personally do not like this idea. I think going mono is a huge compromise. Remember, "...by the Fanatics, for the Fanatics." 😉Rocky said:
I have made a lot of assumptions in my previous post so be aware. It would be a very interesting experiment to see how SPL you could get from the 4001's @ 250Hz.Rocky said:
You could run a passive first order and an active @ 140Hz just in case. Then you can vary the active parameters as needed.Rocky said:
Avantgarde Uno?
Rodd,
What would you say about a setup similar to the Avantgarde Uno speaker, with a TAD tractrix of about 200Hz? (stereo this time 😉) Even though I am seeking to use compression drivers as low as possible, I still fancy the good ribbons or AMTs over horns in the high frequencies, so Raven R1 or R2 might be suitable as tweeter unit..
I know the avantgarde uno midhorn plays down to 220Hz using a horn loaded 4 inch dome, wouldn't I have a good reference in the Uno to find a suitable low-frequency extension for such a project?
What do you think?
Rodd,
What would you say about a setup similar to the Avantgarde Uno speaker, with a TAD tractrix of about 200Hz? (stereo this time 😉) Even though I am seeking to use compression drivers as low as possible, I still fancy the good ribbons or AMTs over horns in the high frequencies, so Raven R1 or R2 might be suitable as tweeter unit..
I know the avantgarde uno midhorn plays down to 220Hz using a horn loaded 4 inch dome, wouldn't I have a good reference in the Uno to find a suitable low-frequency extension for such a project?
What do you think?
Re: Avantgarde Uno?
The idea has possibilities. I heard the Ono at the '03 CES and they were nice, but not as nice as they make out on their web page. It was being played at moderate levels and the sound was smooth and accurate (from what I remember). What I was expecting and didn't hear was the impact and dynamics that brings the music to life.
That said, I noticed right away that the Radian diaphragms are more dynamic then the TAD's, although not quite as smooth and not quite as musical. It could very well be that the TAD integral surround/diaphragm actually limits the dynamics of the stock 4001 driver.
Paul Butterfield (mentioned above) has my old TAD diaphragms and is having some special secret surrounds made to use with the beryllium diaphragms. I will be very interested to hear the outcome of this experiment.
So the point I'm trying to make is that the radians should do better than the TAD's at the lower frequencies. The surrounds are more flexible and the voice coils can handle more power.
Don't forget about the BW each driver will need to cover. Your scenario is using the TAD's to the lower, and possibly the upper limit of their BW. As BW increases so does IM distortion. Couple the wide BW with an already stressed driver from operating at its extreme, and you'll began to sacrifice the sound quality.
The idea has possibilities. I heard the Ono at the '03 CES and they were nice, but not as nice as they make out on their web page. It was being played at moderate levels and the sound was smooth and accurate (from what I remember). What I was expecting and didn't hear was the impact and dynamics that brings the music to life.
That said, I noticed right away that the Radian diaphragms are more dynamic then the TAD's, although not quite as smooth and not quite as musical. It could very well be that the TAD integral surround/diaphragm actually limits the dynamics of the stock 4001 driver.
Paul Butterfield (mentioned above) has my old TAD diaphragms and is having some special secret surrounds made to use with the beryllium diaphragms. I will be very interested to hear the outcome of this experiment.
So the point I'm trying to make is that the radians should do better than the TAD's at the lower frequencies. The surrounds are more flexible and the voice coils can handle more power.
Don't forget about the BW each driver will need to cover. Your scenario is using the TAD's to the lower, and possibly the upper limit of their BW. As BW increases so does IM distortion. Couple the wide BW with an already stressed driver from operating at its extreme, and you'll began to sacrifice the sound quality.
Re: Re: Avantgarde Uno?
Sounds like a good advice. If mating 200Hz horns with Raven R2s, the crossover to the raven can go quite low.. however, I would ofcourse like to have the TAD horns play the entire human voice band up to at least 2000Hz.. This is one decade, or some 3.32 octaves from the horn cutoff frequency.. With active filters the Ravens could be crossed at 2kHz with no problems.. thoughts?
roddyama said:
Sounds like a good advice. If mating 200Hz horns with Raven R2s, the crossover to the raven can go quite low.. however, I would ofcourse like to have the TAD horns play the entire human voice band up to at least 2000Hz.. This is one decade, or some 3.32 octaves from the horn cutoff frequency.. With active filters the Ravens could be crossed at 2kHz with no problems.. thoughts?
Re: Re: Re: Avantgarde Uno?
The old Ma Bell analog lines had a BW from ~200Hz to ~3500Hz. This was suppose to be what is required for intelligible speech. This is ~4 octaves. That's not too bad for a horn loaded speaker.Rocky said:
Re: Re: Re: Re: Avantgarde Uno?
Do you think the TAD drivers will let me get away with this BW (200Hz-3500Hz) clean sounding, taken into consideration their operating conditions down towards 200Hz (it'll probably be down some 10-12dB at 200Hz including both passive and active filter.. active 24dB/oct LR at 200Hz, passive 6dB/oct cap at 250Hz-300Hz)?
roddyama said:
Do you think the TAD drivers will let me get away with this BW (200Hz-3500Hz) clean sounding, taken into consideration their operating conditions down towards 200Hz (it'll probably be down some 10-12dB at 200Hz including both passive and active filter.. active 24dB/oct LR at 200Hz, passive 6dB/oct cap at 250Hz-300Hz)?
Re: Re: Re: Re: Re: Avantgarde Uno?
The TAD driver will do 4 octaves easy if you're starting at 500Hz. Theoretically dropping the BW down an octave should produce the same levels of IM distortion, but it running to the lower extreme that is the question. I don't know what the answer is. Apparently the Ono does it as does the DIY guys with the Sierra horns so there must be something there. If you're up for it, give it a shot. Be prepared to do a lot of tweaking on the X-over (slopes and cut-off freq., hi and lo-pass). The bass driver will need to be in close proximity to the mid horn and the blend of the two will be difficult.Rocky said:
Re^x: Avantgarde Uno?
How does the Avantgarde Uno cope with this? Bass and mid is placed vertically far apart in the Uno setup..?
Edit: I'm reading http://www.avantgarde-usa.com/bass.html at the moment.. does not seem to be the regular TAD or JBL big-inch solution..
roddyama said:
How does the Avantgarde Uno cope with this? Bass and mid is placed vertically far apart in the Uno setup..?
Edit: I'm reading http://www.avantgarde-usa.com/bass.html at the moment.. does not seem to be the regular TAD or JBL big-inch solution..
An externally hosted image should be here but it was not working when we last tested it.
Re: Re^x: Avantgarde Uno?
you have to be further back for best integration. Plus the AG's are notoriously difficult to setup. This is another reason to cross higher - the horn has to be larger to reach lower and by so doing you increase comb filtering and lose point source coherence.
FWIW, I've heard the TAD4001's on the Sierra Brooks Grand 32 - 400 to 450 was approximately as low as he could go and cross successfully. Also, I think you're asking too much of the TAD asking it to cross down at 200. The horn will not sound good all the way down to it's theoretical cut-off., so the horn cutoff has to be lower than you want to go. Also, if you want to cover down to 200 hz you've got to go lower than that to get good integration on the crossover. Playing at 300hz, crossing at 300 hz, and sounding good at 300hz are all different things.
Rocky, I think you're getting off track. The TAD is a beauty in it's own right - let it be the centerpiece of your system by using it where it sounds the best instead of trying to make it fit your ideas of where you want it to work.
Plus, everybody I know has _heard of somebody else_ crossing that low but nobody I know has actually _heard it_ done successfully. I remember reading DAVE A's post to the effect that he had never heard it done successfully ( crossing over 300 to 350) - Which is why he is playing around with an Emilar 600 6" compression driver. Doing it, and doing it right are two different things.
The TAD is a jewel from 500hz up. Use it from there up with a supertweeter passive and if you want to give it a shot pushing the TAD down to 400 or 450 go for it - but leave plenty of room for error on the upside of 400 for best integration with the driver beneath the tad. You can probably make 400 or so going active with a digital crossover and a 48db LR slope - but I'm guessing this will only take you 50 hz or lower than a 24db slope
Fooling around like this cries out for using an active digital crossover _big grin_ Of course, two minutes after I post this, somebody likely will hang a post on the thread saying they're doing it beautifully _grin_
Still, I think I'm pointing you in the right direction when I say to use the TAD where it shines and use something else for the lower-mid bass _big grin_
Regards
Ken L
you have to be further back for best integration. Plus the AG's are notoriously difficult to setup. This is another reason to cross higher - the horn has to be larger to reach lower and by so doing you increase comb filtering and lose point source coherence.
FWIW, I've heard the TAD4001's on the Sierra Brooks Grand 32 - 400 to 450 was approximately as low as he could go and cross successfully. Also, I think you're asking too much of the TAD asking it to cross down at 200. The horn will not sound good all the way down to it's theoretical cut-off., so the horn cutoff has to be lower than you want to go. Also, if you want to cover down to 200 hz you've got to go lower than that to get good integration on the crossover. Playing at 300hz, crossing at 300 hz, and sounding good at 300hz are all different things.
Rocky, I think you're getting off track. The TAD is a beauty in it's own right - let it be the centerpiece of your system by using it where it sounds the best instead of trying to make it fit your ideas of where you want it to work.
Plus, everybody I know has _heard of somebody else_ crossing that low but nobody I know has actually _heard it_ done successfully. I remember reading DAVE A's post to the effect that he had never heard it done successfully ( crossing over 300 to 350) - Which is why he is playing around with an Emilar 600 6" compression driver. Doing it, and doing it right are two different things.
The TAD is a jewel from 500hz up. Use it from there up with a supertweeter passive and if you want to give it a shot pushing the TAD down to 400 or 450 go for it - but leave plenty of room for error on the upside of 400 for best integration with the driver beneath the tad. You can probably make 400 or so going active with a digital crossover and a 48db LR slope - but I'm guessing this will only take you 50 hz or lower than a 24db slope
Fooling around like this cries out for using an active digital crossover _big grin_ Of course, two minutes after I post this, somebody likely will hang a post on the thread saying they're doing it beautifully _grin_
Still, I think I'm pointing you in the right direction when I say to use the TAD where it shines and use something else for the lower-mid bass _big grin_
Regards
Ken L
But are you referring to TADs with original diaphragms, or have you heard them with Radians as well... it IS a more "powerful" diaphragm & VC..
I haven't heard them with Radians
However, I doubt it will change the overall response of the driver dramatically in terms of going down to 200hz.
It's just asking too much of a 2" diaphragm-
For instance - look at the Community range of drivers - the most they can get out of a 2" is 400 hz and that driver is limited on the top end to a 3K crossover point.
to go to 200 hz they go to a 4" compression driver
http://www.northernsound.net/Sales/speakers/community/rawhornsdrivers.html#M200
In this stuff to get something ( in design) you have to give up something - The TAD gets beauty on the top end and gives up the 200/300 hz stuff.
Think about it Rocky - 200hz? Think about the length of the wave.
some physical things you can't get around
1 - you must have overlap in the crossover region
2 - horns do not sound good down to their theoretical cutoff and are not useful all the way to cutoff
3- the lower you go in HZ the more you increase the size of the horn - in a round horn at some point that creates problems with point source coherence and introduces other problems.
Your game plan with the ribbon and using the TAD for lower hz is essentially shifting the usage of the driver to a different bandwidth than for what it was designed.
I've heard the TAD in two configs - one is bare on top with no tweeter, the other usiing the expensive Beryllium supertweeter. Both times with Berylliium diaphragms. They were stunning and the best I have ever heard - a benchmark for me to try to beat with my configuration
IMHO, you should ignore the top end - you can stick a supertweeter up there any time you like - quit trying to stretch it as low as possible - use the TAD as in intended by it's designers and commonly used by others, while spending all of your efforts on achieving an excellent crossover around 500hz - That alone will likely be enough to keep you busy for a long time _grin_
Regards
Ken L
However, I doubt it will change the overall response of the driver dramatically in terms of going down to 200hz.
It's just asking too much of a 2" diaphragm-
For instance - look at the Community range of drivers - the most they can get out of a 2" is 400 hz and that driver is limited on the top end to a 3K crossover point.
to go to 200 hz they go to a 4" compression driver
http://www.northernsound.net/Sales/speakers/community/rawhornsdrivers.html#M200
In this stuff to get something ( in design) you have to give up something - The TAD gets beauty on the top end and gives up the 200/300 hz stuff.
Think about it Rocky - 200hz? Think about the length of the wave.
some physical things you can't get around
1 - you must have overlap in the crossover region
2 - horns do not sound good down to their theoretical cutoff and are not useful all the way to cutoff
3- the lower you go in HZ the more you increase the size of the horn - in a round horn at some point that creates problems with point source coherence and introduces other problems.
Your game plan with the ribbon and using the TAD for lower hz is essentially shifting the usage of the driver to a different bandwidth than for what it was designed.
I've heard the TAD in two configs - one is bare on top with no tweeter, the other usiing the expensive Beryllium supertweeter. Both times with Berylliium diaphragms. They were stunning and the best I have ever heard - a benchmark for me to try to beat with my configuration
IMHO, you should ignore the top end - you can stick a supertweeter up there any time you like - quit trying to stretch it as low as possible - use the TAD as in intended by it's designers and commonly used by others, while spending all of your efforts on achieving an excellent crossover around 500hz - That alone will likely be enough to keep you busy for a long time _grin_
Regards
Ken L
I guess I'll follow your advice, Ken. It would have been an interresting experiment, but I see I'll probably loose more than I gain by streching the TADs capacity downwards.
From a design point of view (or WAF), is there any way I can get good transition at a 500Hz crossover without a large-ish 15 incher?
Any suggestions?
D'Appolito with 10 inchers?
EDIT: the d'appolito was a joke... I think..
From a design point of view (or WAF), is there any way I can get good transition at a 500Hz crossover without a large-ish 15 incher?
- I could use a 12'' and probably get mismatch in polar response,
- I could probably use 2*10'' to get better polar response (is this right?) but I guess I'd lose point source coherence..
Any suggestions?
D'Appolito with 10 inchers?
EDIT: the d'appolito was a joke... I think..
Hi Rocky , all
Since you are interested in using your TADs as far down as possible:
Your Radian domes have a "soft" sourround, they will probably take more punishment for a longer time and still survive than the TAD domes at low frequensies. Probably.
You are going to use them with a low power SET amp.
Therefore you can go lower than 600Hz in the right horn.
How much lower is up to you .
If at all possible take Ken's advice and get a digital crossover.
You make life much easier that way 😉
If you want to go down to 200Hz you'll need a 100Hz horn.
And they are pretty big.
100hz means a theoritical mouth area of 9357 square cm.
Lenght as pure eksponential would be around 170 cm.
A Tractrix would be a little bit shorter.
Would it sound good?
I don't know.
But the only way to find out is to try it and see.
Sounds like fun to me 😉
cheers 😉
Since you are interested in using your TADs as far down as possible:
Your Radian domes have a "soft" sourround, they will probably take more punishment for a longer time and still survive than the TAD domes at low frequensies. Probably.
You are going to use them with a low power SET amp.
Therefore you can go lower than 600Hz in the right horn.
How much lower is up to you .
If at all possible take Ken's advice and get a digital crossover.
You make life much easier that way 😉
If you want to go down to 200Hz you'll need a 100Hz horn.
And they are pretty big.
100hz means a theoritical mouth area of 9357 square cm.
Lenght as pure eksponential would be around 170 cm.
A Tractrix would be a little bit shorter.
Would it sound good?
I don't know.
But the only way to find out is to try it and see.
Sounds like fun to me 😉
cheers 😉