Thanks, it really was a lucky find - consecutive serial numbers to boot! Volts are great drivers, as you've reinforced! Great guy too, sat down for a cuppa and talked about sound stuff for ages. I've just shot an email off to Volt about recommended enclosures...my B220.2 looks extremely similar to the new B220.8.
The best bookshelf speaker I've heard was the Audiomaster MLS3 (still kicking myself for selling it!), and that had a doped Bextrene woofer just like these Volts. I'm hoping for great things.
I need a fairly compact box really, and I don't mind losing a few dB off the bottom end as a compromise so reflex is the way to go. What's the volume and port dimensions of your reflex box? When I get a bigger place in the future though, I'll probably end up building something bigger to let them breath properly.
The compression driver + waveguide combo is going to just sit on top of the cabinet in a little cradle so it doesn't take up any internal volume.
Thanks again for the help.
The best bookshelf speaker I've heard was the Audiomaster MLS3 (still kicking myself for selling it!), and that had a doped Bextrene woofer just like these Volts. I'm hoping for great things.
I need a fairly compact box really, and I don't mind losing a few dB off the bottom end as a compromise so reflex is the way to go. What's the volume and port dimensions of your reflex box? When I get a bigger place in the future though, I'll probably end up building something bigger to let them breath properly.
The compression driver + waveguide combo is going to just sit on top of the cabinet in a little cradle so it doesn't take up any internal volume.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Thanks again for the help.
Hi MQ
First of all these are NOT bookshelf drivers.
The mistake could be made of puting these in too large or smaller box.
I can give you the EXACT spec of my box which is RIGHT end of story.
Sorry to sound so emphatic, but I have been able to spend 20 years worth of dough on records and other stuff, while others waste money SLOWLY crawling the up-grade ladder.
Start as you mean to go on.
I have transmission lines with these in, but I will freely admit I rarely listen to them.
Why ?
The TL's are great as well, but you really do need a VERY large space to make them work well.
Otherwise it's just BASS BASS BASS & more BASS, espec. on the type of music that gets played here.
Better for classical and accoustic stuff.
I just play the reflexes though.
OK basic (not exact) box size is 20x13x10" outside 18mm MDF.
What waveguide & tweeter have you got ?
Personaly I would mount it on the baffle as close to the Volt as possible.
Taking up space in cab doesn't matter to me.
It also means you can move them easyer & no messy wiring hanging around out side everwhere (I did that with the TL's (nightmare)).
These drivers EASY go up to 3K no worrys, and a very simple crossover can be used.
This crossover point clears the important vocal ranges & allows the tweeter to sit on top perfectly and fill in the harmonics and detail.
These drivers are FAB. I hate messy 3 ways with 2 crossover points often aimed in the wrong places.
X at 3K works great with these.
What kind of toonz you spin MQ ?
Cheers
Simon
I'm using a Celestion CDX1-1745 on QSC HPR122 conical constant directivity waveguide. A few people have commented that despite the 10" diameter, that waveguide is mainly round-over so its directivity matches that of an 8-10" midbass quite well. It loads down to 2khz...plenty of potential overlap there. I'll integrate it into the cabinet then...my reason to stick it on top was to get the acoustic centres closer without compromising front baffle strength.
Pic of the waveguide and mounted driver with a AA battery for size comparison:
It'll be biamped with a DBX Driverack, so the crossover can be fiddled with pretty easily and there's oodles of power on tap for the woofer - 150wpc British Citronic pro amp, one of my favourites. Yesyes, it's pretty much the Hitachi MOSFET application circuit with a buffer, but it sounds inexplicably good. I'm thinking to go with a little SE EL84 amp on the HF or maybe a T-amp, but that's another story!
As for music, it's mainly folk, classic rock and a bit of metal thrown in every so often - nothing with really deep bass, but I'm after good transient response. To be honest I'd be happy with a 60hz F3, and unfortunately I lack the space for a T-line. 20"x13"x10" seems like a very manageable size though, I'd appreciate the exact spec if you've got the time. There's a couple sheets of 18mm birch ply in my unit just itching to be made into a speaker...
Right now I've done a rough test run in a random 20l box, and I'm very impressed with the HF response.
Thanks once again. I owe you a virtual pint.
Pic of the waveguide and mounted driver with a AA battery for size comparison:
An externally hosted image should be here but it was not working when we last tested it.
It'll be biamped with a DBX Driverack, so the crossover can be fiddled with pretty easily and there's oodles of power on tap for the woofer - 150wpc British Citronic pro amp, one of my favourites. Yesyes, it's pretty much the Hitachi MOSFET application circuit with a buffer, but it sounds inexplicably good. I'm thinking to go with a little SE EL84 amp on the HF or maybe a T-amp, but that's another story!
As for music, it's mainly folk, classic rock and a bit of metal thrown in every so often - nothing with really deep bass, but I'm after good transient response. To be honest I'd be happy with a 60hz F3, and unfortunately I lack the space for a T-line. 20"x13"x10" seems like a very manageable size though, I'd appreciate the exact spec if you've got the time. There's a couple sheets of 18mm birch ply in my unit just itching to be made into a speaker...
Right now I've done a rough test run in a random 20l box, and I'm very impressed with the HF response.
Thanks once again. I owe you a virtual pint.
Hi MQ
One of the big reasons that particular Volt is such a cracker of a driver is it's very low resonance figure of 28 Hz, YES 28 Hz.
The fact that it works fantasticaly easily up to 3K Hz to me is the icing on the cake !
The response in that enclosure will be approx -3 dB @ 50 Hz, and it has a totaly usable output as the port cuts in (smoothly I will add) down to 30 Hz and even lower.
It has massive excurtion of 25mm p-p and you will have noticed the huge oversized magnet.
Be real carefull with screw-drivers and hard-ware near it, as it will pull things out of your hands !
Have you listened to the Celestion ?
I am doing my first speaker project in 20 years and am thinking I may well use these, what do you think, they seem to get good reports.
I am using a JBL 6"x6" waveguide, good down to 2K, I find it important to have the tweeter as close to the bass as possible.
I would not worry about front baffle strength, there are 3 braces inside my boxes and can be placed fairly freely.
You can also double up on the MDF if you like building muscle (the TL's I made use 36mm MDF.
Nothing wrong with the Hitachi MOSFET build, easy, sounds great, why make life more complex, I have the parts for a mono guitar build one on my desk right now, needs a stalwart PSU and decent signal caps.
Are you thinking of banging an EL84 together ?
I have a couple of pp EL84's I'm refurbing at present, very nice.
Also have some 6BQ5's for an SE project.
If your looking for a REALLY cool EL84 SE circuit, check out the Decware.com design, hyper minimal, no feedback, not much signal path, NNIICCEE.
When you say nothing with really deep bass, It's probably just that you haven't heard it YET, you will with the Volts in spades !
Bass players on the net seem to say there's no fundamental energy in a 30 Hz bass string, what a load of cobblers, they just can't hear it cos' the speakers have too high resonance, and drop off too quick.
If I play a low B on the Volt's the cones want to jump out at me ! They reproduce LOW !
That's the reason for my new speaker project.
Tell me MQ, why did that guy sell you the Volts for £50, they are worth about £300 inc P+P new.
He must be a total idiot to sell them, What was he using them for ? or were they unused from an incomplette project or something ?
Cheers
Simon
They were on an Ebay auction with a bad title missing keywords like "woofer" and "speaker" so I don't think many people's searches found them. I popped in a bid of £80 at the last knockings, fully expecting to be outbid massively but I was pleasantly surprised!
These are pretty old drivers; Volt's phone number on the box is the old 9 digit one! Apparently this guy bought them for a build which never happened, and they ended up sitting in his back room for 15 years until he cleared it out on ebay. And yep, the magnet length is something I haven't seen on many drivers...plenty of linear xmax. It managed to pull that AA battery from a good few inches away.
The Celestions are very nice, effortless airy vocals like large-format JBLs. Only caveat is that they roll off very sharply (but cleanly!) at around 18khz, but Celestion themselves agree with EQing that out. I actually looked at using the 6x6 JBL but I couldn't find a dealer willing to order it in for me without a massive shipping surcharge. Feel free to borrow the Celestions for a couple of weeks if you're in London! The magnet is massive for a 1" exit thing, and the diaphragm is used in quite a lot of other Celestion compression drivers too.
Ampage wise, the EL84 is a modified Magnavox pull...new filter caps, film input caps, all the usual jazz. Sounds very nice although it lacks low end because of the small output transformers. For ease of use though, I'm probably going to stick with solid state; being so efficient, the Celestions won't need more than a few watts in my smallish room so a TA2020 based T-amp should be fine.
Looking forward to seeing the dimensions and port of your reflex cabs. Hopefully should be able to get building end of next week!
These are pretty old drivers; Volt's phone number on the box is the old 9 digit one! Apparently this guy bought them for a build which never happened, and they ended up sitting in his back room for 15 years until he cleared it out on ebay. And yep, the magnet length is something I haven't seen on many drivers...plenty of linear xmax. It managed to pull that AA battery from a good few inches away.
The Celestions are very nice, effortless airy vocals like large-format JBLs. Only caveat is that they roll off very sharply (but cleanly!) at around 18khz, but Celestion themselves agree with EQing that out. I actually looked at using the 6x6 JBL but I couldn't find a dealer willing to order it in for me without a massive shipping surcharge. Feel free to borrow the Celestions for a couple of weeks if you're in London! The magnet is massive for a 1" exit thing, and the diaphragm is used in quite a lot of other Celestion compression drivers too.
Ampage wise, the EL84 is a modified Magnavox pull...new filter caps, film input caps, all the usual jazz. Sounds very nice although it lacks low end because of the small output transformers. For ease of use though, I'm probably going to stick with solid state; being so efficient, the Celestions won't need more than a few watts in my smallish room so a TA2020 based T-amp should be fine.
Looking forward to seeing the dimensions and port of your reflex cabs. Hopefully should be able to get building end of next week!
Hi MQ
Just looking at your photo again.
It might seem savage, but I would seriously think about cutting into the 10" waveguide if it were me, and matching it to the squared off part of the Volt, as per many commercial speaker models.
What thickness is your plywood ?
The cab volume may need redimensioning, to acomodate that waveguide, but with volume and port the same, which I don't see as a problem.
I think mounting the HF unit on the baffle is essential to integrate the sound toggether.
There are 3 internal braces, and the cab walls were generously covered with acoustic foam/bitumen sandwich material.
Some of the expensive foam acoustic damping products around arn't worth s*&% in my opinion.
CPC who I'm sure you know as a diyer, do a BAF/wool mix stuffing, which is exellent.
The cabs are entirely filled with this kind of fill, and the resolution and speed goes up massively as a result of this.
I feel that a lot of speakers are under-stuffed.
Another good and cheap damping material is 'Evo-Stick' self adhesive bitumen 'flashband' material from B&Q etc. I would use the self adhesive & staple to the cab walls. This totally damps the cab.
The foam stuff CPC sells I personaly think is rubbish, I am looking for something myself at the moment foam wise, I'll let you know if I find anything that looks good.
It's a must to flash some cash on these treatments.
Have you seen 'Neutrik Speakon tm' connectors (the best IMO).
Tell me about your drive-rack.
I was looking at products like this the other day myself.
I have never tried to EQ my monitors, as they are always played at the same volume, and have not felt the need.
There is a feeling though, that with my new build speakers, some kind of EQ experiments could be interesting.
I have an SPL parametric EQ here at Space Egg, which I may experiment with in due course.
I can check this out on the net of course, but does the DBX have mic. in & pink noise ? What model do you have ? Any good ?
Cheers
Simon
Just looking at your photo again.
It might seem savage, but I would seriously think about cutting into the 10" waveguide if it were me, and matching it to the squared off part of the Volt, as per many commercial speaker models.
What thickness is your plywood ?
The cab volume may need redimensioning, to acomodate that waveguide, but with volume and port the same, which I don't see as a problem.
I think mounting the HF unit on the baffle is essential to integrate the sound toggether.
There are 3 internal braces, and the cab walls were generously covered with acoustic foam/bitumen sandwich material.
Some of the expensive foam acoustic damping products around arn't worth s*&% in my opinion.
CPC who I'm sure you know as a diyer, do a BAF/wool mix stuffing, which is exellent.
The cabs are entirely filled with this kind of fill, and the resolution and speed goes up massively as a result of this.
I feel that a lot of speakers are under-stuffed.
Another good and cheap damping material is 'Evo-Stick' self adhesive bitumen 'flashband' material from B&Q etc. I would use the self adhesive & staple to the cab walls. This totally damps the cab.
The foam stuff CPC sells I personaly think is rubbish, I am looking for something myself at the moment foam wise, I'll let you know if I find anything that looks good.
It's a must to flash some cash on these treatments.
Have you seen 'Neutrik Speakon tm' connectors (the best IMO).
Tell me about your drive-rack.
I was looking at products like this the other day myself.
I have never tried to EQ my monitors, as they are always played at the same volume, and have not felt the need.
There is a feeling though, that with my new build speakers, some kind of EQ experiments could be interesting.
I have an SPL parametric EQ here at Space Egg, which I may experiment with in due course.
I can check this out on the net of course, but does the DBX have mic. in & pink noise ? What model do you have ? Any good ?
Cheers
Simon
It's 18mm stuff, dead sturdy and pretty tough but I'll still be adding plenty of hardwood braces. I like the idea of using bitumen on the inside, and I've got plenty of grey speaker stuffing lying around. That or the usual polyfill has worked for me in the past. I've heard good things about using lead flashing tacked to the inside to kill resonances, although I imagine it needs gluing to prevent buzzing.
I'm probably going to go with MDF for the baffle though, simply to make the rebates easier.
To be honest, I'd go passive if I was any good at designing crossovers. The Driverack does the constant directivity correction EQ for the HF section, which would otherwise be difficult (for me at least...) in passive form. Another advantage of active is being able to dial in a delay to perfectly time align the signals, which IMO improves vocal coherency greatly. There's no phase errors and to my ears, the Driverack and Behringer DCX are both completely transparent and don't affect the noise floor, even when using a sensitive HF driver. I'd say the only letdown is needing four amp channels and a lot of cabling...
It has got an RTA, pink noise generator and auto room correction function using a measurement mic, but to be honest both RTA and correction is pretty pants. It's not worth choosing one unit over another for, that's for sure! The display is too small and there's not enough X axis resolution to be practical, and the room correction only works with the not-constant-Q graphic EQ...which generally makes a mess of things. There's a parametric and graphic EQ built in, which are both very good and intuitive with a little graph to show how wide the Q is.
Overall, I'd heartily recommend a processor like the Driverack or Behringer DCX. Very handy when prototyping as padding, crossover slopes and corrective EQ can be applied quickly and easily.
The waveguides have already been chopped a bit to accomodate the Celestions, so I'm not afraid of removing some of the round-off to help it mate with the woofer better. The flat sides of the basket are just asking for that! After all, even when mounted flush, the acoustic centres are fairly far apart still, thanks for the tip.
I'm probably going to go with MDF for the baffle though, simply to make the rebates easier.
To be honest, I'd go passive if I was any good at designing crossovers. The Driverack does the constant directivity correction EQ for the HF section, which would otherwise be difficult (for me at least...) in passive form. Another advantage of active is being able to dial in a delay to perfectly time align the signals, which IMO improves vocal coherency greatly. There's no phase errors and to my ears, the Driverack and Behringer DCX are both completely transparent and don't affect the noise floor, even when using a sensitive HF driver. I'd say the only letdown is needing four amp channels and a lot of cabling...
It has got an RTA, pink noise generator and auto room correction function using a measurement mic, but to be honest both RTA and correction is pretty pants. It's not worth choosing one unit over another for, that's for sure! The display is too small and there's not enough X axis resolution to be practical, and the room correction only works with the not-constant-Q graphic EQ...which generally makes a mess of things. There's a parametric and graphic EQ built in, which are both very good and intuitive with a little graph to show how wide the Q is.
Overall, I'd heartily recommend a processor like the Driverack or Behringer DCX. Very handy when prototyping as padding, crossover slopes and corrective EQ can be applied quickly and easily.
The waveguides have already been chopped a bit to accomodate the Celestions, so I'm not afraid of removing some of the round-off to help it mate with the woofer better. The flat sides of the basket are just asking for that! After all, even when mounted flush, the acoustic centres are fairly far apart still, thanks for the tip.
Hi MQ
Yeah the whole time alignment thing really hits me.
Nice thing about the CD tweeters is, the origin is from the same point.
My monitors are always on their sides with the tweeters facing inwards, toed-in.
I find it absolutely crazy listening to speakers where the tweets are above/bellow the woof.
I've even managed to annoy people I visit by tipping their speakers on their sides !
I'm yet to hear an analogue graphic that sounds acceptable.
The DBX stuff is good, I had wondered about risking a DBX graphic, but am dubious that I would end up not useing it in the long-run.
Mail order 30 days on VISA are good though, but I've never had to return anything.
The SPL parametric is interesting as it is 'invisible', vari Q, notch, freq etc. 4 channels of it, enough to dial in a low end curve & something around the crossover point.
I'm not sure what you mean about the constant directivity EQ's ? explain ?
If you've got a sheet of ply going spare, I would seriously double up the thickness if you could.
OK bit more weight, but it's not for an iPod.
I didn't do this on my reflexes, but I did on the transmission lines, and BOY what a difference ! easy to hear.
The top, sides & back were all laminated with screws & glue to 36mm, well worth doing I think. If the reflexes weren't already painted etc. I would do the same.
Some people do PC RTA, but I haven't investigated this.
It all comes down to how good the measurement mic is at the end of the day, and I have to say I doubt the quality of these at under 300 notes, my ears are cheaper & tell me what I need to know.
I asked about the constant directivity EQ cos these speakers obviously have a X-over, (what does the constant directivity EQ seek to achieve ?).
Very simple, minimal parts & transparent to my ears, the Celestion needs padding down alot compared to the Volt.
I like the idea of a teenie toob amp, like the gorgeous EL84 on the Celestion.
With the amount of HF that little baby kicks out, you'd only need a couple o' watts to go deaf !
Cheers
Simon
P.S. rubber car foot matting from skip dives is good for glueing to cab walls.
Yeah the whole time alignment thing really hits me.
Nice thing about the CD tweeters is, the origin is from the same point.
My monitors are always on their sides with the tweeters facing inwards, toed-in.
I find it absolutely crazy listening to speakers where the tweets are above/bellow the woof.
I've even managed to annoy people I visit by tipping their speakers on their sides !
I'm yet to hear an analogue graphic that sounds acceptable.
The DBX stuff is good, I had wondered about risking a DBX graphic, but am dubious that I would end up not useing it in the long-run.
Mail order 30 days on VISA are good though, but I've never had to return anything.
The SPL parametric is interesting as it is 'invisible', vari Q, notch, freq etc. 4 channels of it, enough to dial in a low end curve & something around the crossover point.
I'm not sure what you mean about the constant directivity EQ's ? explain ?
If you've got a sheet of ply going spare, I would seriously double up the thickness if you could.
OK bit more weight, but it's not for an iPod.
I didn't do this on my reflexes, but I did on the transmission lines, and BOY what a difference ! easy to hear.
The top, sides & back were all laminated with screws & glue to 36mm, well worth doing I think. If the reflexes weren't already painted etc. I would do the same.
Some people do PC RTA, but I haven't investigated this.
It all comes down to how good the measurement mic is at the end of the day, and I have to say I doubt the quality of these at under 300 notes, my ears are cheaper & tell me what I need to know.
I asked about the constant directivity EQ cos these speakers obviously have a X-over, (what does the constant directivity EQ seek to achieve ?).
Very simple, minimal parts & transparent to my ears, the Celestion needs padding down alot compared to the Volt.
I like the idea of a teenie toob amp, like the gorgeous EL84 on the Celestion.
With the amount of HF that little baby kicks out, you'd only need a couple o' watts to go deaf !
Cheers
Simon
P.S. rubber car foot matting from skip dives is good for glueing to cab walls.
EQ is needed on any constant directivity waveguide as the high frequencies are rolled off at about 3dB per octave (largely dependant on w/guide design though) about 2.5khz or so to maintain pattern control. It needs a lift to keep the response flat...the Econowave crossover does this with a passive low shelf filter, but it's better in many ways to do it with an active parametric EQ. That's what my Driverack's doing. There's a very good explanation of CD EQ on the Peavey site, but I can't seem to find it.
For example, here's my latest measurement of the CDX1-1745 on HPR122i waveguide, gated and smoothed with no EQ applied. Note how at 10k, it's 13dB down.
Still working on the EQ in LspCAD, haven't come up with anything truly satisfactory yet.
I use an Audix TR40 (cheapish mic) with an ART preamp and FuzzMeasure as a basic computer based RTA setup. The TR40 is reasonably flat from 800hz til 14khz, which is the region I mainly need it for. You pay more for a better mic which is flat from 10hz upwards...money I can't afford!
Some of the high end pro graphic EQs are very good, much more transparent than the majority of the consumer offerings. Rane, Ashly, Klark-Technik etc. all make some excellent EQs which can be had for about £200-300 used. Considering a Klark costs just over £1k new, it's not too bad. Rane's Constant Q series are especially nice IMO...much easier to cleanly cut a band. To be honest, the Behringer DCX sounds just as good as the DBX Driverack, don't be put off by the Berry namebadge on the front!
I'll consider doubling up the walls if there's enough wood. These seem to demand a well-damped cabinet!
Thanks again for the help. Your cabinet volume and port sizes would be rather helpful!
For example, here's my latest measurement of the CDX1-1745 on HPR122i waveguide, gated and smoothed with no EQ applied. Note how at 10k, it's 13dB down.
An externally hosted image should be here but it was not working when we last tested it.
Still working on the EQ in LspCAD, haven't come up with anything truly satisfactory yet.
I use an Audix TR40 (cheapish mic) with an ART preamp and FuzzMeasure as a basic computer based RTA setup. The TR40 is reasonably flat from 800hz til 14khz, which is the region I mainly need it for. You pay more for a better mic which is flat from 10hz upwards...money I can't afford!
Some of the high end pro graphic EQs are very good, much more transparent than the majority of the consumer offerings. Rane, Ashly, Klark-Technik etc. all make some excellent EQs which can be had for about £200-300 used. Considering a Klark costs just over £1k new, it's not too bad. Rane's Constant Q series are especially nice IMO...much easier to cleanly cut a band. To be honest, the Behringer DCX sounds just as good as the DBX Driverack, don't be put off by the Berry namebadge on the front!
I'll consider doubling up the walls if there's enough wood. These seem to demand a well-damped cabinet!
Thanks again for the help. Your cabinet volume and port sizes would be rather helpful!
I've got a Volt .pdf notice about it.
fs = 27 Hz
Qt = 0.24
Vas = 52 liters
Sd = 190 cm²
Xmax = +/- 5.25 m
You can find description here :
Volt Loudspeakers - About Us
Go to "Loudspeakers", then to "Studio", then to "B220.2"
About everybody speaking about Volt drivers is absolutely fan of them. However discussions about them are rare. I would like to see them tested by Zaph Audio.
.
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Thanks, but this isn't the B220.2 - it's the BM220.2, which is a completely different animal...looks very different too. The B prefix means it's optimised for bass usage below 1khz whereas the BM designates it as a bass/midrange driver.
I've been talking with someone who contacted Volt about a recone kit for the BM220.2 a couple years ago; they said to use the one for the BM220.8, so they must be very similar. Haven't got a reply from Volt yet though...
Hi again MQ
Yeah, that wall thickening did the biz on my TL's.
I dont even think it's about resonances of anything like that.
I think it really helps for a speaker with a V8 muscle driver like the Volt to simply have some weight behind it, not about resonance in my opinion.
People rattle on (no pun intended) about resonances, but have you ever tried hitting a lump of MDF with a hammer ? It's hardly the best material to make a glockenspiel out of !
I have an early 90's vintage Berry compresor here at Space Egg.
I paid £300 quid for the darn ting back den.
Fine piece of kit, I does exactly what it says on the tin.
Simply 'compresses' that's it, no character, no vintage special effects, just good solid compression up to pretty high ratios.
Hit the 'Auto' button if you can't be bothered to twiddle & 90% of the time works a dream.
Popped the hood on it one day to check it's pedigre, full of original DBX comp. chips etc. Basicaly a DBX clone.
LED's on it drive me nuts, as they bleed into the next door LED, just needs black paint around the LED's to shade them (Mmmm...must get round to doing that some time).
The Berry measurement mic is not a good recording mike, which makes me wonder about it.
I think if I had £300 quid to burn on a measurement mic I'd go for the bottom of the range Josephson, they make some real cool mics.
Still not sure about this constant directivity EQ.
My main concern is 'on-axis' real world listening.
Moving away from centre gives you mono anyhow, forget about what freq.
The less HF I have bouncing around at the sides the better IMO.
Not sure how it effects these JBL waveguides I have.
Have you seen the Karlson-Coupler waveguide 'tubes', very interesting.
Karlson worked with NASA on acoustics during the early space program.
A space age dude !
Cheers
Simon
Hi MQ
Stanley and I just sorted out the cabinet dimensions for you.
507 x 342 x 267 external size
477 x 312 x 237 internal size
(yes made out of 15mm MDF, not 18mm as previously stated)
The 'front' is the 507 x 267 dimension
PORT - 220mm long, 2.5" internal diameter plastic drainpipe of some sort, epoxyed in place.
Port was mounted central, below woof & 20mm from inside cab wall, does not chug or wheeze.
BRACES - 3 internal braces along the 267mm dimension, each 15mm x 75mm
One brace on front between woof & tweet, 2 braces unevenly spaced on back, centred on diameter of Volt magnet.
Generous bitumen foam pad sandwiches on cabinet walls.
Cabinet stuffed generously with BAF etc. (totaly filled up, but not compressed).
These cabinet proportions 'work', you may have to re-proportion with that large waveguide.
Personaly I like the 1:1.6:2.5 ratios if pos, or at least 'uneven' for safety.
Some think this is rubbish, I hope they enjoy listening to the standing waves in their cabinets !
Cheers
Simon
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