>>> The limited Xmax doesn't appear to be an issue, and according to my cheap SPL metre, in my room at least the response just isn't rising at all; not with EL34s driving them...
I am driving mine with EL34 amp too... I did not know you were also. I would not say they sound like they have a rising response. They have a liquid, fluid sound in the mids that really impresses. Maybe they just allow the tubes to show their stuff.
Godzilla
I am driving mine with EL34 amp too... I did not know you were also. I would not say they sound like they have a rising response. They have a liquid, fluid sound in the mids that really impresses. Maybe they just allow the tubes to show their stuff.
Godzilla
Scottmoose said:Very old post indeed Jim.Yes, & a different pair with 165s. Nice sounding combination with several examples, including 'Zilla's.
Thanks for the reply Scott. I'll give those dimensions a shot.
Did you hold the slanting internal baffel about a 1/2" down from the top opening?
Yes, but that is very old, so may I suggest you use one of the Excel sheets to size the box volume? If it's too tall, raise the notional tuning frequency (remember, you'll get plenty of useable output at least half an octave below that) a little to get a practical horn length -you'll note that the WxD dimensions will alter to maintain the ~ideal volume.
is bigger better for a coral 4A-70 10cm wideband?
hi there bib builders, greetings from new zealand,
i am lucky enough to have a pair of very smooth and natural sounding coral 4A-70 drivers in (a quick and dirty) set of the manufacturers recommended (12litre) ported enclosures.... highs and mids excellent, bass uneven and very 'porty'.
i wonder if the 4A-70's would suit a BiB enclosure but must admit that i lack the nous to calculate the proper parameters from the driver specs i can find... perhaps the more experienced hands behind this thread can help me with determining the proper dimensions for a bigger, better cabinet.
the corals are 1 kg each, alnico magnet, paper cone with an alloy dome, 40W max music power, 8 Ohm, 90dB/w-m, 85Hz- 20kHz freq range, 85Hz resonant freq, flux density 11,000 gauss, total flux 75,000 maxwells, 4.45cm effective cone radius, 2.7g Mo, 0.42 Qo
from - http://img149.imageshack.us/img149/4300/coralfw7.jpg
internal dimensions for recommended sealed enclosures - fob 93Hz, 38 litres, 515/275/515 ; fob 103Hz, 15 litres, 410/205/179 (h/w/d in mm)
from - http://de.geocities.com/peter_rehkop/encl3.jpg
i look forward to reading your thoughts, thanks all, adam
hi there bib builders, greetings from new zealand,
i am lucky enough to have a pair of very smooth and natural sounding coral 4A-70 drivers in (a quick and dirty) set of the manufacturers recommended (12litre) ported enclosures.... highs and mids excellent, bass uneven and very 'porty'.
i wonder if the 4A-70's would suit a BiB enclosure but must admit that i lack the nous to calculate the proper parameters from the driver specs i can find... perhaps the more experienced hands behind this thread can help me with determining the proper dimensions for a bigger, better cabinet.
the corals are 1 kg each, alnico magnet, paper cone with an alloy dome, 40W max music power, 8 Ohm, 90dB/w-m, 85Hz- 20kHz freq range, 85Hz resonant freq, flux density 11,000 gauss, total flux 75,000 maxwells, 4.45cm effective cone radius, 2.7g Mo, 0.42 Qo
from - http://img149.imageshack.us/img149/4300/coralfw7.jpg
internal dimensions for recommended sealed enclosures - fob 93Hz, 38 litres, 515/275/515 ; fob 103Hz, 15 litres, 410/205/179 (h/w/d in mm)
from - http://de.geocities.com/peter_rehkop/encl3.jpg
i look forward to reading your thoughts, thanks all, adam
coral 4A-70 - t/s parameters....
hi,
the numbers i posted are the only ones i can find... i was hoping it was possible to derive the necessary values from them.
or does that require voice coil diameter, turns etc.
might be worth building a bib to an educated guess... easier for me to have woodwork done than have the speakers tested....
have been driving them with a direct coupled single ended amp, a 5W 6A3 stereo unit, really shows the drivers have potential and deserve to be in a great enclosure,
thanks, adam
hi,
the numbers i posted are the only ones i can find... i was hoping it was possible to derive the necessary values from them.
or does that require voice coil diameter, turns etc.
might be worth building a bib to an educated guess... easier for me to have woodwork done than have the speakers tested....
have been driving them with a direct coupled single ended amp, a 5W 6A3 stereo unit, really shows the drivers have potential and deserve to be in a great enclosure,
thanks, adam
Re: coral 4A-70 - t/s parameters....
thanks for all your feedback...
will seek out someone to test the drivers for me; may just slap together a cabinet from zayne742's suggested dimensions - get a feel for the build and the sound...
i appreciate your input folks, i'm very taken by the wideband approach, (good rhythm, great tone) and look forward to reporting on my experience with the 4A-70's.
have a dim memory of finding t/s parameters somewhere obscure on the web last year, will post 'em if i find 'em,
regards, adam
thanks for all your feedback...
will seek out someone to test the drivers for me; may just slap together a cabinet from zayne742's suggested dimensions - get a feel for the build and the sound...
i appreciate your input folks, i'm very taken by the wideband approach, (good rhythm, great tone) and look forward to reporting on my experience with the 4A-70's.
have a dim memory of finding t/s parameters somewhere obscure on the web last year, will post 'em if i find 'em,
regards, adam
coral pictures, and other things of interest
here is link to picasa page where i have just posted pics of the coral widerangers in ported boxes; will follow up with unboxed corals and stages of bib build number 1.
http://picasaweb.google.com/arustyrednail/
checked back in at axent audio, amazing place where i got the corals, key man there thought proposed dimensions for bib a good first shot. has been through every alignment known to man in his time, including different forms of tl etc.
more news as it happens,
adam
here is link to picasa page where i have just posted pics of the coral widerangers in ported boxes; will follow up with unboxed corals and stages of bib build number 1.
http://picasaweb.google.com/arustyrednail/
checked back in at axent audio, amazing place where i got the corals, key man there thought proposed dimensions for bib a good first shot. has been through every alignment known to man in his time, including different forms of tl etc.
more news as it happens,
adam
thanks for enabl pattern alex
hello forum folk,
not sure the current ported box is worth elaborating, just a mule, had drivers lying around naked for some time and just had to get them some kind of home...
there is now a fair supply of inch thick ply to use for a second go at the ported cab and more than enough to try the 12litre sealed job - and a trial bib as well.
will see what stiffer, stronger walls do for the tone and extension - and how the 3 different enclosures compare.
am very grateful to justin (captain of the boat in picasa snaps) for his time and trouble in indulging my audio curiosity. has a chap with cabinetmaking experience on staff now...
easter greetings to all,
thanks, a
hello forum folk,
not sure the current ported box is worth elaborating, just a mule, had drivers lying around naked for some time and just had to get them some kind of home...
there is now a fair supply of inch thick ply to use for a second go at the ported cab and more than enough to try the 12litre sealed job - and a trial bib as well.
will see what stiffer, stronger walls do for the tone and extension - and how the 3 different enclosures compare.
am very grateful to justin (captain of the boat in picasa snaps) for his time and trouble in indulging my audio curiosity. has a chap with cabinetmaking experience on staff now...
easter greetings to all,
thanks, a
Greets!
Unless you build a straight, full height BIB (pointed end down) and space it up to get the driver high enough, then better to floor load such a high Fs driver.
WRT specs:
Sd = 62.211 cm^2
Qo = ~Qts = ~0.42
Mo = ~Mms = ~2.7 g
Fs = 85 Hz
Vas = ~7.166 L
where:
Vas = 0.01*po*c^2*Sd^2/((2*PI()*Fs)^2*Mms)
po = ~1.21 Kg/m^3
c = ~344.43 m/s
Sd in cm^2
Mms is in grams
Assuming a 2.5 ohms system output impedance, then Qo/Qts = ~0.55, making a maximally flat vented alignment ~19.93 L/63.4 Hz and making for a little bit larger BIB than Zayne's. All this is pure speculation based on somewhat erroneous data/assumptions, but based on the cab specs you used and your comment on its performance that implies too small a cab tuned too high, I feel they're well within the 'ballpark', though of course using measured specs is best.
Anyway, please let us know how the BIB turns out, etc..
GM
Unless you build a straight, full height BIB (pointed end down) and space it up to get the driver high enough, then better to floor load such a high Fs driver.
WRT specs:
Sd = 62.211 cm^2
Qo = ~Qts = ~0.42
Mo = ~Mms = ~2.7 g
Fs = 85 Hz
Vas = ~7.166 L
where:
Vas = 0.01*po*c^2*Sd^2/((2*PI()*Fs)^2*Mms)
po = ~1.21 Kg/m^3
c = ~344.43 m/s
Sd in cm^2
Mms is in grams
Assuming a 2.5 ohms system output impedance, then Qo/Qts = ~0.55, making a maximally flat vented alignment ~19.93 L/63.4 Hz and making for a little bit larger BIB than Zayne's. All this is pure speculation based on somewhat erroneous data/assumptions, but based on the cab specs you used and your comment on its performance that implies too small a cab tuned too high, I feel they're well within the 'ballpark', though of course using measured specs is best.
Anyway, please let us know how the BIB turns out, etc..
GM
the trusty corals
hi,
looks like there is an overwhelming consensus to please have the coral's bench tested...
the place i got the drivers is a marvelous treasure house of vintage drivers but not the most advanced customer service culture - am a little reluctant to take the corals back in... might be a while before i see them again...
however, the collective wisdom of the forum is not to be taken lightly, so, will see if i can get those parameters pinned down...
no woodwork this easter break, maybe next weekend,
best wishes, a
hi,
looks like there is an overwhelming consensus to please have the coral's bench tested...
the place i got the drivers is a marvelous treasure house of vintage drivers but not the most advanced customer service culture - am a little reluctant to take the corals back in... might be a while before i see them again...
however, the collective wisdom of the forum is not to be taken lightly, so, will see if i can get those parameters pinned down...
no woodwork this easter break, maybe next weekend,
best wishes, a
coral freq response curves
hi,
just got back from having coral's tested.... tech suggested that they would run well open baffle, (and really needed a sub one litre sealed box to test properly, although didn't have small enough box to hand).
he a bit shocked that had run drivers full range, as thought were mid range unit. suggested handing off to woofer between 500 and 1000Hz...
curve printout is very faint dot matrix (!) and i will need to adjust contrast when scanning.
will see to that tomorrow, have to go to copy shop,
happy trails,
a
hi,
just got back from having coral's tested.... tech suggested that they would run well open baffle, (and really needed a sub one litre sealed box to test properly, although didn't have small enough box to hand).
he a bit shocked that had run drivers full range, as thought were mid range unit. suggested handing off to woofer between 500 and 1000Hz...
curve printout is very faint dot matrix (!) and i will need to adjust contrast when scanning.
will see to that tomorrow, have to go to copy shop,
happy trails,
a
Help with 208Esigma/T90 BIB
Been enjoying my 208/t90 BIBs for some time now but with changing amps I have a problem I am trying to address.
Recently I built a Tubelab Simple SE. This is an amazing amp and with KT88 tubes incredibly dynamic acorss the whole range. However this setup has revealed an upper mid glare that detracts from the overall sound. The drivers are well run in and I have cut back the T90 and even taken it out of circuit but the anomaly remains. Changing tubes reduces it somewhat but also reduces the incredible dynamics of the KT88s.
I know my room is very "live" with lots of hard surfaces which does not help.
A friend found this which is helpful:
"Full range speaker setups can be a bit peaky on the upper midrange. In fact I have much the same issue myself. It can be an on axis issue associated with beaming from the sharp cone profile of the driver. It can be an artifact of the baffle suddenly disappearing. It can be an issue with the back wave reinforcing front wave at a critical point - in this case it is likely that there will be dips either side of the peak making it sound even worse.
Unfortunately the better the amp the more you are likely to notice these artifacts of your speakers.
Shoog"
Do those with these drivers (or anybody else) have the same issues? Have you managed to deal with it? I would be grateful for any help here.
Been enjoying my 208/t90 BIBs for some time now but with changing amps I have a problem I am trying to address.
Recently I built a Tubelab Simple SE. This is an amazing amp and with KT88 tubes incredibly dynamic acorss the whole range. However this setup has revealed an upper mid glare that detracts from the overall sound. The drivers are well run in and I have cut back the T90 and even taken it out of circuit but the anomaly remains. Changing tubes reduces it somewhat but also reduces the incredible dynamics of the KT88s.
I know my room is very "live" with lots of hard surfaces which does not help.
A friend found this which is helpful:
"Full range speaker setups can be a bit peaky on the upper midrange. In fact I have much the same issue myself. It can be an on axis issue associated with beaming from the sharp cone profile of the driver. It can be an artifact of the baffle suddenly disappearing. It can be an issue with the back wave reinforcing front wave at a critical point - in this case it is likely that there will be dips either side of the peak making it sound even worse.
Unfortunately the better the amp the more you are likely to notice these artifacts of your speakers.
Shoog"
Do those with these drivers (or anybody else) have the same issues? Have you managed to deal with it? I would be grateful for any help here.
coral curves, hot of the press
hi,
please visit picasaweb.google.com/arustyrednail coral project album for the
curves measured by 'axent audio' tech yesterday, bottom two the relevant ones:
the one marked sealed is the cabinet posted earlier, with its port plugged. box fairly unstuffed as i overstuffed and destuffed in stages, less stuffing more lively sounding
the curve labelled open air is, well, open air - and to my unschooled eye - looks rather good...
the other two graphs: i think the topmost is port open.... the next one down is the bottom pair of curves on the same printout ( which is not dot matrix... just has that feel )
should point out my front room is rather small, tall and live sounding, will measure it...
so, near to mid field listening, and you'd be surprised at the apparent bass there is from those smart little drivers - though alt country works better than dub,
thanks all, a
hi,
please visit picasaweb.google.com/arustyrednail coral project album for the
curves measured by 'axent audio' tech yesterday, bottom two the relevant ones:
the one marked sealed is the cabinet posted earlier, with its port plugged. box fairly unstuffed as i overstuffed and destuffed in stages, less stuffing more lively sounding
the curve labelled open air is, well, open air - and to my unschooled eye - looks rather good...
the other two graphs: i think the topmost is port open.... the next one down is the bottom pair of curves on the same printout ( which is not dot matrix... just has that feel )
should point out my front room is rather small, tall and live sounding, will measure it...
so, near to mid field listening, and you'd be surprised at the apparent bass there is from those smart little drivers - though alt country works better than dub,
thanks all, a