I have had this pair of Stephens Trusonic 80fr sitting around for years and I'm finally motivated to do something with them. I made demo cabinet out of MDF to the originally specified size and played poorly. It sounds like it needs a baffle step correction because it sounds like the vocals are coming out through a paper cup. I don't really understand baffle step correction. I have read some writing on it but still a little confused. How is it caused? If corrected by 3db or 6db am I losing that sensitivity in the driver?
Here are links to the measurement graph that someone in japan did:
Trusonic 80FR - CLIPX Audio
Here are the specs for the driver:
???? ??? - Stephens Trusonic ???? ???? 80FR 120FR
I would like to do something with it because they are vintage cool and they were made where I grew up: Culver City, CA, which is inland from Venice Beach, so there is a hometown sentiment to them.
Should I do a reflex, sealed or FAST OB? Any recommendations much appreciated.
Here are links to the measurement graph that someone in japan did:
Trusonic 80FR - CLIPX Audio
Here are the specs for the driver:
???? ??? - Stephens Trusonic ???? ???? 80FR 120FR
I would like to do something with it because they are vintage cool and they were made where I grew up: Culver City, CA, which is inland from Venice Beach, so there is a hometown sentiment to them.
Should I do a reflex, sealed or FAST OB? Any recommendations much appreciated.
looks like a helper tweeter would be useful. You could take a 1mH-2mH inductor, put two terminals of an 8 ohm L-pad across the inductor, put that pair in series with the speaker - then adjust by ear.
It should play well in a Karlson 12. A driver specific K-coupler could be simulated by xrk971 as long as the parameters are close to what's specified in the Japanese link and with amplifier damping factor or type known. It may not need BSC in the Karlson although I had to use that with a Gradient brand 8" fullrange.
It could work in the Karlsonator. A stock Karlsonator 8 is tuned to 40Hz - which may (?) be somewhat low.
It should play well in a Karlson 12. A driver specific K-coupler could be simulated by xrk971 as long as the parameters are close to what's specified in the Japanese link and with amplifier damping factor or type known. It may not need BSC in the Karlson although I had to use that with a Gradient brand 8" fullrange.
It could work in the Karlsonator. A stock Karlsonator 8 is tuned to 40Hz - which may (?) be somewhat low.
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By using an L-PAD in series that would lower the overall efficiency of the driver, no? Would I then match the new efficiency with a compatible tweeter? I have seen Karlson cabinets and I understand that they way they are constructed is that they reinforce the bass somehow.
I am not sure what "xrk971" is?
The damping factor of the amp is 12.5.
Thanks for your help! I'm beginning to understand the possibilities for these speakers.
a line level baffle step circuit usually consists of a resistor in parallel with an inductor. "xrk971" is a Diyaudio member and prime contributor in speaker and amplifier threads. He's good with the the acoustic abacus program called "Akabak" which is useful for working with various loudspeaker models.
that should be a nice speaker once a tweeter is added and blended
you would use two adjacent terminals of an L-pad for the variable resistor,
then if you find a sweet spot,measure that resistance, then buy a 20 watt fixed resistor of that
value for a permanent filter.
it can be handy to take an L-pad and have a couple of leads with decent alligator clips for such work
as BSC, and series attenuating pads for tweeters.
the Karlson enclosure can sometimes negate the need for a BSC. I have a case where the 100-200Hz octave is so
strong that it really needs to be shelved 6dB down fo match the mids and highs of an Eminence Beta10cx coax.
that should be a nice speaker once a tweeter is added and blended
you would use two adjacent terminals of an L-pad for the variable resistor,
then if you find a sweet spot,measure that resistance, then buy a 20 watt fixed resistor of that
value for a permanent filter.
it can be handy to take an L-pad and have a couple of leads with decent alligator clips for such work
as BSC, and series attenuating pads for tweeters.
the Karlson enclosure can sometimes negate the need for a BSC. I have a case where the 100-200Hz octave is so
strong that it really needs to be shelved 6dB down fo match the mids and highs of an Eminence Beta10cx coax.
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a line level baffle step circuit usually consists of a resistor in parallel with an inductor. "xrk971" is a Diyaudio member and prime contributor in speaker and amplifier threads. He's good with the the acoustic abacus program called "Akabak" which is useful for working with various loudspeaker models.
that should be a nice speaker once a tweeter is added and blended
you would use two adjacent terminals of an L-pad for the variable resistor,
then if you find a sweet spot,measure that resistance, then buy a 20 watt fixed resistor of that
value for a permanent filter.
it can be handy to take an L-pad and have a couple of leads with decent alligator clips for such work
as BSC, and series attenuating pads for tweeters.
the Karlson enclosure can sometimes negate the need for a BSC. I have a case where the 100-200Hz octave is so
strong that it really needs to be shelved 6dB down fo match the mids and highs of an Eminence Beta10cx coax.
Wow! Thanks for the great useful and usable information. The image and description of the circuit is easy to understand. I really like the Karlson idea for the performance, looks, and the lack of need for a BSC circuit. Not using the BSC circuit would allow the efficiency to remain high. Here's a drawing I did of the Karlson info that I found while attempting to integrate a tweeter:
An externally hosted image should be here but it was not working when we last tested it.
I am not sure about time alignment but I tried to illustrate an example the best way I know how. I suppose it's going to take trial and error with REW.
I'll keep posting on the progress. And please send me your thoughts and opinions.
By the way, if I could get 40hz in the Karlosn cab I would be super happy!
Don't tempt me. That's what I originally wanted to do. I even bought a minidsp but I think the investment with extra amp and all is too much for me right now.
the stock Karlsonator8 might be about right. Its about the same bulk as a K12 but tuned a half octave lower and has a skinnier aspect. - about 40Hz for a Karlsonator8 vs ~60Hz for K12. A K12 probably would have more "hit" in the 100-200Hx octave.
xrk971, if he has time, could run those specs. Thejessman, who owns Triticum Audio, built and measured a pair of Karlsonator8 loaded with the inexpensive Visaton BG20, so that gives a baseline.
A tweeter on top would be moved back. A felt pad under and in front of the tweeter would reduce reflections.
Karlsonator8 plan - as mentioned, its tuning using this plan is about 40Hz - maybe 42. I'd like a pair for my 1772 if suitable.
https://lh3.googleusercontent.com/Z...TpCeXGMjqMobia902qaluMwa4q-OGg=w2048-h1609-no
here's the relevant specs for 80FR as Akabak needs
Def_Driver 'Stephens 80FR' (94.39dB)
Sd= 214.08
fs=65.165
Mms= 9.8
Qms=4.915
Qes=0.614
Re=5.92
BL=6.22 Tm
Le=0.5
Vas=39.62 liter
Here's Jesse's Karlsonator8 build at Facebook
https://www.facebook.com/media/set/?set=a.645456515500837.1073741837.601735219872967&type=3
F6 (6dB down point/ quarter power) was about 42Hz with BG20 outdoors - his highs would have looked stronger if the mic
had been centered on the dustap-whizzer axis. The 8 inch version of the Karlsonator looks better than the 12" Karlsonator but I think he didn't have any fill in the "stub". Karlsonator12 works well with 12LTA and Nirvana10
xrk971, if he has time, could run those specs. Thejessman, who owns Triticum Audio, built and measured a pair of Karlsonator8 loaded with the inexpensive Visaton BG20, so that gives a baseline.
A tweeter on top would be moved back. A felt pad under and in front of the tweeter would reduce reflections.
Karlsonator8 plan - as mentioned, its tuning using this plan is about 40Hz - maybe 42. I'd like a pair for my 1772 if suitable.
https://lh3.googleusercontent.com/Z...TpCeXGMjqMobia902qaluMwa4q-OGg=w2048-h1609-no
here's the relevant specs for 80FR as Akabak needs
Def_Driver 'Stephens 80FR' (94.39dB)
Sd= 214.08
fs=65.165
Mms= 9.8
Qms=4.915
Qes=0.614
Re=5.92
BL=6.22 Tm
Le=0.5
Vas=39.62 liter
Here's Jesse's Karlsonator8 build at Facebook
https://www.facebook.com/media/set/?set=a.645456515500837.1073741837.601735219872967&type=3
F6 (6dB down point/ quarter power) was about 42Hz with BG20 outdoors - his highs would have looked stronger if the mic
had been centered on the dustap-whizzer axis. The 8 inch version of the Karlsonator looks better than the 12" Karlsonator but I think he didn't have any fill in the "stub". Karlsonator12 works well with 12LTA and Nirvana10
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Hmm, interesting way to view time delay
. Maybe, maybe not, got to see your example before commenting.
GM
I also have a trusonic fr80 that I want to use for a mono single speaker system.
Looking for some cab ideas. I would love to try it in a Karlson but not sure of my woodworking skills to build one. What size cab and port would work for this speaker in a bass reflex, a more simple folded horn, or what about open baffle
Looking for some cab ideas. I would love to try it in a Karlson but not sure of my woodworking skills to build one. What size cab and port would work for this speaker in a bass reflex, a more simple folded horn, or what about open baffle
I found this, although i cant guess what this cab might look like inside.
FS: Edgarhorn Stephens Trusonic! HO LEE FUK! Must see. | Super Best Audio Friends
FS: Edgarhorn Stephens Trusonic! HO LEE FUK! Must see. | Super Best Audio Friends
http://www.diyaudio.com/forums/full-range/304455-stephens-trusonic-80fr.html
Don't recall any MLTL drawings for this particular driver, but a quick sim in Hornresp yielded a fairly large one due to the driver's relatively weak motor, but simple to build and should perform quite well down to ~40 Hz, so covers all but some modern music, movie recordings.
L = 60"
WxD = 155"^2
driver offset = 24.25"
vent = 33.1875"^2/6.5" dia.
vent offset = 50.4"
All dims inside [i.d.] and approximate. The driver is 1.5" below the average 38" ear height normally used [assuming 3/4" thick material], so add a massive base if more height is required plus a double top plate is desirable too since this is where the highest acoustic pressure is.
I typically line the top, one side and back down to the vent with 1" acoustic fiberglass insulation, but most folks around here don't like to use it, so damp internally with polyfil, shredded jeans or similar by ear to 'taste'.
Bracing need not be elaborate, I use bits of scrap closet rod dowel or similar to make functionally the same as this heavily machined motor brace: http://frugal-phile.com/boxlib/GM-A10-MLTL.pdf
It can be a solid board, though ideally make the cab a bit wider to offset this lost volume and damp the side facing the undamped wall.
GM
Don't recall any MLTL drawings for this particular driver, but a quick sim in Hornresp yielded a fairly large one due to the driver's relatively weak motor, but simple to build and should perform quite well down to ~40 Hz, so covers all but some modern music, movie recordings.
L = 60"
WxD = 155"^2
driver offset = 24.25"
vent = 33.1875"^2/6.5" dia.
vent offset = 50.4"
All dims inside [i.d.] and approximate. The driver is 1.5" below the average 38" ear height normally used [assuming 3/4" thick material], so add a massive base if more height is required plus a double top plate is desirable too since this is where the highest acoustic pressure is.
I typically line the top, one side and back down to the vent with 1" acoustic fiberglass insulation, but most folks around here don't like to use it, so damp internally with polyfil, shredded jeans or similar by ear to 'taste'
.Bracing need not be elaborate, I use bits of scrap closet rod dowel or similar to make functionally the same as this heavily machined motor brace: http://frugal-phile.com/boxlib/GM-A10-MLTL.pdf
It can be a solid board, though ideally make the cab a bit wider to offset this lost volume and damp the side facing the undamped wall.
GM
Thanks GM
Can you clarify for me since I am new at this, would this cab design be an empty rectangle volume inside? Ive seen some MLTL designs but they have a dividing tapered part inside.
Like a simple bass reflex? 60" x 10" x 15"
What is "vent 33.1875"^2/6.5 dia." ?
If u can explain I would really appreciate it . I want to try and build it.
Can you clarify for me since I am new at this, would this cab design be an empty rectangle volume inside? Ive seen some MLTL designs but they have a dividing tapered part inside.
Like a simple bass reflex? 60" x 10" x 15"
What is "vent 33.1875"^2/6.5 dia." ?
If u can explain I would really appreciate it . I want to try and build it.
The Stephens drivers are a thing of beauty. Cherish them. With their edge-wound rectangular copper windings and very light moving mass, hardly obsolete at all and better than many new mega-weight contemporary drivers.
In days of yore, they were favourites for Karlsons. I had a 15-inch Stephens in a K15 and loved the sound, 50 yrs ago.
Hard to go wrong simply supplementing the treble with a silk dome tweeter from Parts Express and just a capacitor to high-pass the tweeter. (since they can play low, not critical to have too sharp a crossover slope). Simple.
Ben
In days of yore, they were favourites for Karlsons. I had a 15-inch Stephens in a K15 and loved the sound, 50 yrs ago.
Hard to go wrong simply supplementing the treble with a silk dome tweeter from Parts Express and just a capacitor to high-pass the tweeter. (since they can play low, not critical to have too sharp a crossover slope). Simple.
Ben
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