Hi Dave, looking for advice!
Seeing that i was about to mess up Andrea´s thread i start this as i can´t stop fiddling with the idea of a TL for the RCF L12P48.
4 meters of pipe will make a large cabinet but could be kept within 250l. I´ve looked around but cant find any reference to TL´s for this driver.
In the late 70´s i got hold of a few KLH 10" units ( i think same as in the Baron ). Reading an article in HiFi news and a 60´s book by Klinger i designed a 30Hz TL ( very much a copy of IMF´s Monitor and the HiFi news Radford design )
This came out faboulus with good extension and stupid definition, could play pretty loud with a PL400 too. When the KLH supply ran dry and yet a friend wanted a pair i bought two Peerless 10" that on paper looked ideal, also in real life looked very similar to the KLH units, a bit smaller magnet. This ended up in disaster, no bass whatsoever! Sounded like a kitchen radio and as i did´nt know where to look for problem my TL career took a break then. Ready to take it up again, but would realy appreciate all advice and input, I dont mind failure in cabinetbuilding can allways put the wrecks in the fireplace but would like to know more this time.
Seeing that i was about to mess up Andrea´s thread i start this as i can´t stop fiddling with the idea of a TL for the RCF L12P48.
4 meters of pipe will make a large cabinet but could be kept within 250l. I´ve looked around but cant find any reference to TL´s for this driver.
In the late 70´s i got hold of a few KLH 10" units ( i think same as in the Baron ). Reading an article in HiFi news and a 60´s book by Klinger i designed a 30Hz TL ( very much a copy of IMF´s Monitor and the HiFi news Radford design )
This came out faboulus with good extension and stupid definition, could play pretty loud with a PL400 too. When the KLH supply ran dry and yet a friend wanted a pair i bought two Peerless 10" that on paper looked ideal, also in real life looked very similar to the KLH units, a bit smaller magnet. This ended up in disaster, no bass whatsoever! Sounded like a kitchen radio and as i did´nt know where to look for problem my TL career took a break then. Ready to take it up again, but would realy appreciate all advice and input, I dont mind failure in cabinetbuilding can allways put the wrecks in the fireplace but would like to know more this time.
Well, I´m not Dave but if you can´t find a TL-design with that driver (which is rare anyway) you´ll need the T/S-parameters of it and play a bit with the mathcad-worksheets of Martin King.
You can download this great tool here.
There´s also quite a bit theory to get you started.
What really helped me alot was also Bob brines site.
Besides you´ll find a lot of threads here where GM (forum member) gave insight on how to tackle TL-design and the like. Can´t find that thread for now but will get back.
Jens
You can download this great tool here.
There´s also quite a bit theory to get you started.
What really helped me alot was also Bob brines site.
Besides you´ll find a lot of threads here where GM (forum member) gave insight on how to tackle TL-design and the like. Can´t find that thread for now but will get back.
Jens
True, but with a driver like this, any theoretical sonic advantage of a TL is wasted on a low tuned alignment since any 'nasties' of a mass loaded one has decayed away by the time it gets high enough in frequency for us to perceive. Also, to keep amplitude distortion low, a fairly low XO point is required.
Assuming these specs, the step response of this 16Hz ML-TL is a 'beautiful thing'
:
Fs = 19 Hz
Vas = 270 L
Re = 5 ohms
Qes = 0.44
Qms = 4.4
Qms = 0.4
Le = 3 mH (estimated)
BL = 11.3985
Sd = 506.709 cm^2 (estimated)
L (in) 84.154
S0/SL mult. 2.4367
S0/SL (in^2) 191.376
X0/Zdriver (in) 29.673
vent (in) 81.15
rp = 3"
Lp = 17"
density = 0.2lbs/ft^3
Vas or Vb(ft^3) 9.32
Fs or Fb (Hz) 16
Due to its length, the footprint is small, so either standing up or laying down up against a wall could be made semi-unobstrusive if color and/or pattern matched to either the wall or floor. Even folded in half it's not all that big (by my standards).
GM
Assuming these specs, the step response of this 16Hz ML-TL is a 'beautiful thing'
:Fs = 19 Hz
Vas = 270 L
Re = 5 ohms
Qes = 0.44
Qms = 4.4
Qms = 0.4
Le = 3 mH (estimated)
BL = 11.3985
Sd = 506.709 cm^2 (estimated)
L (in) 84.154
S0/SL mult. 2.4367
S0/SL (in^2) 191.376
X0/Zdriver (in) 29.673
vent (in) 81.15
rp = 3"
Lp = 17"
density = 0.2lbs/ft^3
Vas or Vb(ft^3) 9.32
Fs or Fb (Hz) 16
Due to its length, the footprint is small, so either standing up or laying down up against a wall could be made semi-unobstrusive if color and/or pattern matched to either the wall or floor. Even folded in half it's not all that big (by my standards
).GM
Allright!!
Thanks GM (its not You making all the Corvette´s is it)
This looks like something, 215cm long pipe folded makes ideal height for putting the AMT on top. X-over will be 80-100Hz active starting with the old Accuphase P300 as amp until i´m finished with the bridged Zen v5.
What i dont understand is the lenght, 215 cm would be fs of roughly 40 Hz, but there´s a few figures in Yor post i´m not familiar with, could You direct me to a place of info?
The guys at the local lumberyard are eagerly awaiting my next purchase and my Wife looking at sketch of this cabinet deemed it nice and small.
Thanks GM (its not You making all the Corvette´s is it)
This looks like something, 215cm long pipe folded makes ideal height for putting the AMT on top. X-over will be 80-100Hz active starting with the old Accuphase P300 as amp until i´m finished with the bridged Zen v5.
What i dont understand is the lenght, 215 cm would be fs of roughly 40 Hz, but there´s a few figures in Yor post i´m not familiar with, could You direct me to a place of info?
The guys at the local lumberyard are eagerly awaiting my next purchase and my Wife looking at sketch of this cabinet deemed it nice and small.
>Thanks GM (its not You making all the Corvette´s is it)
====
You're welcome! No, owned/hotrodded a few in what some say was a misspent youth though.
====
>What i dont understand is the lenght, 215 cm would be fs of roughly 40 Hz, but there´s a few figures in Yor post i´m not familiar with, could You direct me to a place of info?
====
This is a mass loaded TL, so doesn't need to be anywere near a 1/4WL long. MJK's http://www.quarter-wave.com/ should enlighten you.
====
>.......as English is not native to me it sometimes take a while to understand abbreviations.
====
Sorry about that, so many of you with 'foreign' names communicate so well in English that I have to look at the flag to make sure you're not a 'local'. Anyway, so many folks now are using MJK's Mathcad PORTED and/or MLTQWT worksheets that I just post what to input in the various fields so that all you have to do is plug them in, then scroll down to get it to calculate the various graphs. Note that it calculates Qts, so no need to input it.
Actually, I need to update my design calculator to list 'Zport' in lieu of 'vent'.
GM
====
You're welcome! No, owned/hotrodded a few in what some say was a misspent youth though.
====
>What i dont understand is the lenght, 215 cm would be fs of roughly 40 Hz, but there´s a few figures in Yor post i´m not familiar with, could You direct me to a place of info?
====
This is a mass loaded TL, so doesn't need to be anywere near a 1/4WL long. MJK's http://www.quarter-wave.com/ should enlighten you.
====
>.......as English is not native to me it sometimes take a while to understand abbreviations.
====
Sorry about that, so many of you with 'foreign' names communicate so well in English that I have to look at the flag to make sure you're not a 'local'. Anyway, so many folks now are using MJK's Mathcad PORTED and/or MLTQWT worksheets that I just post what to input in the various fields so that all you have to do is plug them in, then scroll down to get it to calculate the various graphs. Note that it calculates Qts, so no need to input it.
Actually, I need to update my design calculator to list 'Zport' in lieu of 'vent'.
GM
Thanks again GM and Dave!
Tried Mathcad and did a Check in JBL Speakershop. So i nailed a crude chipboard proto together and tested.
This makes a real crazy bass unit! I get definition on par with a voice of the theatre but at 20 Hz! All the low frequency resolution that this RCF driver is unique in is still there but tendency to "overshoot or sluggishness" is all gone.
As i´m a bit oldfasioned on drawings, first paper, pen, ruler and the old TI and then the cad drawing i´ll need this weekend before posting anything.
Will supply all drawings and photos as this will be adaptable to other drivers.
Tried Mathcad and did a Check in JBL Speakershop. So i nailed a crude chipboard proto together and tested.
This makes a real crazy bass unit! I get definition on par with a voice of the theatre but at 20 Hz! All the low frequency resolution that this RCF driver is unique in is still there but tendency to "overshoot or sluggishness" is all gone.
As i´m a bit oldfasioned on drawings, first paper, pen, ruler and the old TI and then the cad drawing i´ll need this weekend before posting anything.
Will supply all drawings and photos as this will be adaptable to other drivers.
Youth is ment to be unwisely spent, otherwise, we would have been made accountants right after high school.
You're welcome! I guess the published specs were 'close enough' then. Pity these drivers are no longer available, they modeled really nice, and from your remarks, perform to match.
Yeah, I never let work get in the way of my hobbies. I could have worked harder at making money, but I wouldn't have had as much fun or appreciate/enjoy what I would have bought nearly as much as making/tweaking things.
GM
Yeah, I never let work get in the way of my hobbies.
I could have worked harder at making money, but I wouldn't have had as much fun or appreciate/enjoy what I would have bought nearly as much as making/tweaking things.GM
Long time no seat
So what happened? While fiddling and testing with the prototype pipes the RCF units lying on the floor, the Cat decides to eat the the foam surrounds. No, honnestly, i did not kill the cat, she´s still around here, destroying something else. I declared her a "non-friend" and refused to feed her for several hours.
So! I decided to venture along another route. As GM says - loud is beatifull, and cats don´t eat cloth surrounds. Went the efficiency way and used an Eminence Kappa Pro 12 in a pretty traditional TQWT. Used for a while now, most of the time driven by an old Mark Levinson ML11. It does´nt get much more fun than this. Top is B&C DE900 1,4" driver in wood horn powered by Zen V5 ( when not burned out) or homebreew EL34 class A push-pull stage, so-so, good opt´s though.
So what happened? While fiddling and testing with the prototype pipes the RCF units lying on the floor, the Cat decides to eat the the foam surrounds. No, honnestly, i did not kill the cat, she´s still around here, destroying something else. I declared her a "non-friend" and refused to feed her for several hours.
So! I decided to venture along another route. As GM says - loud is beatifull, and cats don´t eat cloth surrounds. Went the efficiency way and used an Eminence Kappa Pro 12 in a pretty traditional TQWT. Used for a while now, most of the time driven by an old Mark Levinson ML11. It does´nt get much more fun than this. Top is B&C DE900 1,4" driver in wood horn powered by Zen V5 ( when not burned out) or homebreew EL34 class A push-pull stage, so-so, good opt´s though.
Attachments
Greets!
'Sounds' like a plan!
Cats are cool, but now you know why all mine are yard pets! Anyway, if you try again, here's a 12 Hz one just completed: http://www.mach5audio.com/download/bassboy.pdf
GM
'Sounds'
like a plan! Cats are cool, but now you know why all mine are yard pets! Anyway, if you try again, here's a 12 Hz one just completed: http://www.mach5audio.com/download/bassboy.pdf
GM
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