Re: pinkmouse drawings
Roger:
Agreed about that curvy hardwood baffle! The basic, tall, pointy enclosure doesn't have to be hard though. People get worried over the long, angled side, and how to cut it accurately. Look at it this way: Place one rectangular sheet of your chosen material on the floor. Attach the side and top panels (good idea to double the top panel in these things BTW) to it, at the appropriate anges. Then add a second, rectangular sheet. Wait until everything's dried, then simply trim and plane into shape. Bingo! If you, like me, have no chance of doing the side baffle, then a flat panel, nicely veneered, and attached to the main enclosure would work just as well.
Best
Scott
freo said:
Roger:
Agreed about that curvy hardwood baffle! The basic, tall, pointy enclosure doesn't have to be hard though. People get worried over the long, angled side, and how to cut it accurately. Look at it this way: Place one rectangular sheet of your chosen material on the floor. Attach the side and top panels (good idea to double the top panel in these things BTW) to it, at the appropriate anges. Then add a second, rectangular sheet. Wait until everything's dried, then simply trim and plane into shape. Bingo! If you, like me, have no chance of doing the side baffle, then a flat panel, nicely veneered, and attached to the main enclosure would work just as well.
Best
Scott
Scott, quick question. I was laying out a cutting list for the towers, and there is quite a bit of material wastage. What's the performance hit for going down to a 12" deep cab rather than the 13.75"
Thanks
Thanks
I've just run a quick check and you're in luck according to MathCad anyway: almost nothing is the answer. That's the sim result below.
Oh yes: if you find the cabs too bass-heavy, increase the port length to 4". That will roll things off below 100Hz whilst keeping the same F10. Sm is reduced to 3.55Sd and So to 0.888Sd respectively (or very close). All other dimesnions remain as described.
Best
Scott
Oh yes: if you find the cabs too bass-heavy, increase the port length to 4". That will roll things off below 100Hz whilst keeping the same F10. Sm is reduced to 3.55Sd and So to 0.888Sd respectively (or very close). All other dimesnions remain as described.
Best
Scott
Attachments
You're welcome.
One other fun possibility. This cabinet layout and geometary lends itself to having a bass unit like the B139 or perhaps a good 10" job next to a vertical array of perhaps 8-10 decent quality cheap ribbons beside the vertical edge of the enclosure. OK, the cabinet dimesnions would probably need juggling, but that's not difficult. To the best of my knowledge, no-one's done that yet. Could be interesting for future reference!
E.g. The Seas CA25FEY paper-cone unit has an Fs of 33Hz, and, nominally trundles up to 3KHz, which ought to be useful. Crossing over to a set of Dayton PT2 ribbons should be easy enough at circa 2500Hz.
Best
Scott
One other fun possibility. This cabinet layout and geometary lends itself to having a bass unit like the B139 or perhaps a good 10" job next to a vertical array of perhaps 8-10 decent quality cheap ribbons beside the vertical edge of the enclosure. OK, the cabinet dimesnions would probably need juggling, but that's not difficult. To the best of my knowledge, no-one's done that yet. Could be interesting for future reference!
E.g. The Seas CA25FEY paper-cone unit has an Fs of 33Hz, and, nominally trundles up to 3KHz, which ought to be useful. Crossing over to a set of Dayton PT2 ribbons should be easy enough at circa 2500Hz.
Best
Scott
I'm fitting a new Falcon 8ohm isobarik X-over into a speaker that uses a B139/B110/Audax H12x9D25.
However the B139 (as Lynn Olsen points out) has got a 12dB peak at 1.1kHz that I want to take out with a simple notch filter. Has anyone got a link to the SP1044 frequency plot from KEF?
This'll be a series C-L-R across the B139.
Looking at the series notch filter calculator:
http://www.carstereo.com/help/Articles.cfm?id=23
it appears that I need the values of Fs, Qms, Qes and Re.
I've plugged in Fs = 1100 (this is the 1.1kHz peak, not the major Fs of 25), Qms of 5.5, Qes of 0.4 and Re of 4.87.
As Qes and Qms refer to the Fs=25 I assume these are wrong but I have no Q values for the 1.1kHz resonance. I'm also assuming that Re is used and not RE.
So I get the values of 74.3uF, 0.28mH, 5.22ohms, probably not correct though.
Has anyone already done the proper notch filter for the B139? I'm guessing this is a popular mod!!
However the B139 (as Lynn Olsen points out) has got a 12dB peak at 1.1kHz that I want to take out with a simple notch filter. Has anyone got a link to the SP1044 frequency plot from KEF?
This'll be a series C-L-R across the B139.
Looking at the series notch filter calculator:
http://www.carstereo.com/help/Articles.cfm?id=23
it appears that I need the values of Fs, Qms, Qes and Re.
I've plugged in Fs = 1100 (this is the 1.1kHz peak, not the major Fs of 25), Qms of 5.5, Qes of 0.4 and Re of 4.87.
As Qes and Qms refer to the Fs=25 I assume these are wrong but I have no Q values for the 1.1kHz resonance. I'm also assuming that Re is used and not RE.
So I get the values of 74.3uF, 0.28mH, 5.22ohms, probably not correct though.
Has anyone already done the proper notch filter for the B139? I'm guessing this is a popular mod!!
I recently dida 4-way using the B139 in a TL as the bass unit.
Also used the T15 tweeter that came with the B139 from original Kef speaker.
The dimensions of my TL are pretty close to the original TL used by Rogers (iirc).
http://users.tpg.com.au/users/gradds/ARGOS/manhattan.html
I must do something about the raw mdf look at some stage and take some more pics !! 🙄
Also used the T15 tweeter that came with the B139 from original Kef speaker.
The dimensions of my TL are pretty close to the original TL used by Rogers (iirc).
http://users.tpg.com.au/users/gradds/ARGOS/manhattan.html
I must do something about the raw mdf look at some stage and take some more pics !! 🙄
Globulator said:
Hi,
The 1.1kHz frequency may vary between B139 types.
Best to confirm by ear using some test tones.
All you need is an air cored inductor DCR 1R to 2R and a capacitor.
1R gives a deeper but less wide dip than 2R.
You can use that calculator,
set Qms = 10, Re = 1 to 2 R and you can vary Qes which is around 3 for 4 for 12dB.
🙂/sreten.
Globulator said:
Hi,
The 1.1kHz frequency may vary between B139 types.
Best to confirm by ear using some test tones.
All you need is an air cored inductor DCR 1R to 2R and a capacitor.
1R gives a deeper but less wide dip than 2R.
You can use that calculator,
set Qms = 10, Re = 1 to 2 R and you can vary Qes which is around 3 for 4 for 12dB.
🙂/sreten.
P.S. How do you get a 8 ohm Isobarik ?
Hi sreten,
Thanks for the info, I'll have a try with those values. I have some Behringer stuff that should in theory be able to pickup the frequency response via pink noise so I will try that to get the exact values.
This should be easier as I am moving the crossover outside into the 'plinth' so I can fiddle and measure.
The original Isobarik had two 8 ohm crossovers made by falcon, one for each set of three speakers.
This speaker was a DIY copy of an isobarik by a relative of mine, so it is very strongly braces and has the full 12mm bitumen damping etc, and made to the same external dimensions. The theory was that it was much cheaper than a real Isobarik - and so it was. My relative later upgraded to real isobariks. It however has an Audax (similar specs to the D2008) but just used a Key DN12 crossover internally and a bass port.
I decided it sounded better without the port so I plugged that up, and now time has given me a chance to rip out the old crossover (with small components - and different values to the real isobarik crossover) and put in the 'proper' ones in a plinth I'll screw onto the bottom.
This should upgrade the sound to a sort of 8ohm isobarik , it always had a very pleasant sound so I'm hoping to get a little more solidity and clarity out of it. My new Usher x708 pair basically wiped the floor with them in all respects so something had to be done 😉.
I'll then try driving it off firstly a Sansui G7000 until my tube amps Sansui 1000A and Pioneer sx800 are ready to rumble, to try and get the impact and realism that I remember from a new pair of isobariks powered by a Russ Andrews tube amp gave to 'Floyd's The Wall.
Thanks for the info, I'll have a try with those values. I have some Behringer stuff that should in theory be able to pickup the frequency response via pink noise so I will try that to get the exact values.
This should be easier as I am moving the crossover outside into the 'plinth' so I can fiddle and measure.
The original Isobarik had two 8 ohm crossovers made by falcon, one for each set of three speakers.
This speaker was a DIY copy of an isobarik by a relative of mine, so it is very strongly braces and has the full 12mm bitumen damping etc, and made to the same external dimensions. The theory was that it was much cheaper than a real Isobarik - and so it was. My relative later upgraded to real isobariks. It however has an Audax (similar specs to the D2008) but just used a Key DN12 crossover internally and a bass port.
I decided it sounded better without the port so I plugged that up, and now time has given me a chance to rip out the old crossover (with small components - and different values to the real isobarik crossover) and put in the 'proper' ones in a plinth I'll screw onto the bottom.
This should upgrade the sound to a sort of 8ohm isobarik , it always had a very pleasant sound so I'm hoping to get a little more solidity and clarity out of it. My new Usher x708 pair basically wiped the floor with them in all respects so something had to be done 😉.
I'll then try driving it off firstly a Sansui G7000 until my tube amps Sansui 1000A and Pioneer sx800 are ready to rumble, to try and get the impact and realism that I remember from a new pair of isobariks powered by a Russ Andrews tube amp gave to 'Floyd's The Wall.
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