I would like to design a new box & xover for these drivers that I have. I am new to this so where would be a good starting point? I see lots of info on these drivers but I cant find actual plans for cabinet or X over. I would rather follow someone that has had success rather then venture on my own for my 1st project.
Thanks for any support.
Thanks for any support.
Hi,
Not much mileage in rebuilding the Zenith Allegro 3000's.
For a first project take a look at :
X-LS Classic kit
rgds, sreten.
Not much mileage in rebuilding the Zenith Allegro 3000's.
For a first project take a look at :
X-LS Classic kit
rgds, sreten.
You'll ideally need to measure your woofer's specs to come up with a cab alignment [size/tuning]. If your woofers are Rola 16 ohm 49-1240, then hopefully these will be close enough: http://www.diyaudio.com/forums/atta...s-cabinet-suggestions-zenith-rola-49-1240.pdf
GM
GM
The quality of the Allegro boxes suck.
You have the newer ones without a removable back. You'll have to cut that off to get at the drivers.
The tweeter is the short Foster alnico horn, in this case with a very thick blue styrofoam "gasket" that extends the horn lenth a bit (<10mm from memory).
The woofer likely is a ferrite magneted one... i have seen at least 3 different manufacturers. Could be Rolas like the attached picture.
dave
You have the newer ones without a removable back. You'll have to cut that off to get at the drivers.
The tweeter is the short Foster alnico horn, in this case with a very thick blue styrofoam "gasket" that extends the horn lenth a bit (<10mm from memory).
The woofer likely is a ferrite magneted one... i have seen at least 3 different manufacturers. Could be Rolas like the attached picture.
dave
Attachments
Amazing what gets you interested. These look quite fun.
A closed box 10" paper driver with cloth surround can sound good. Zenith run it full range then use a second order filter on the horn tweeter. Cap, Coil, 12R to tweeter.
It originally came with grill cloth. I think you need to see if you can't just remove the battens and staples around the vent, and see if you can't knock in the reflex box enough to get your hand in. Then you can probably unscrew the bass and tweeter. You could try the bass first, but I have a feeling the nuts might just turn and turn, but you might get lucky and find the bolts grip the speaker chassis direct.
All a bit of a fiddle, but these things usually benefit from a better filter. Filters aren't hard. Add some BAF wadding too.I've done this sort of speaker before. It ends up excellent.
A closed box 10" paper driver with cloth surround can sound good. Zenith run it full range then use a second order filter on the horn tweeter. Cap, Coil, 12R to tweeter.
It originally came with grill cloth. I think you need to see if you can't just remove the battens and staples around the vent, and see if you can't knock in the reflex box enough to get your hand in. Then you can probably unscrew the bass and tweeter. You could try the bass first, but I have a feeling the nuts might just turn and turn, but you might get lucky and find the bolts grip the speaker chassis direct.
All a bit of a fiddle, but these things usually benefit from a better filter. Filters aren't hard. Add some BAF wadding too.I've done this sort of speaker before. It ends up excellent.
Attachments
The vent would have to be pulled out. Even if you could undo the nuts on the drivers you couldn't get the drivers out,
1st order mod on these is removing the back. Then work out a cabinet and build a new one. The box they come in is crap.
dave
You can drill the bolts on the bass, probably working upside down. And with eye protection.
Then get the bass aside and cut a couple of slices into the bass hole, and get the bass out sideways maybe? Depends how deep it is. Then fix the cuts and mount everything on the outside?
Might work.
Then get the bass aside and cut a couple of slices into the bass hole, and get the bass out sideways maybe? Depends how deep it is. Then fix the cuts and mount everything on the outside?
Might work.
That's one way, though FWIW, way back when I found these types of 'curb queens' to be a bit 'boomy' due to being too small/tuned too high, so would make a tall floor standing version [AKA MLTL nowadays] to get a more extended, 'tight' bass and raise the HF up to average seated ear height/whatever using the same internal width/depth cross sectional area [CSA], then adjusted tuning, internal damping mostly by ear with it located wherever you want it in room.
If you're willing to gamble a bit of time/$$ to build one out of scrap/whatever to experiment with to see if it can be tuned to perform enough better overall to justify making a pair of properly constructed cabs, which typically will sound better overall and usually with less internal damping due to the cab's 1/4 WL pipe action, then I need to know at what height off the floor you want the HF.
GM
If you're willing to gamble a bit of time/$$ to build one out of scrap/whatever to experiment with to see if it can be tuned to perform enough better overall to justify making a pair of properly constructed cabs, which typically will sound better overall and usually with less internal damping due to the cab's 1/4 WL pipe action, then I need to know at what height off the floor you want the HF.
GM
Expanding upon GM's recommendation, you could do the following empirical experiment for pretty cheap:
1. Use a jigsaw/sawzall to remove a large section of the top or bottom of one enclosure. Remove drivers and port. Block the driver/port holes with cutout panel and scrap ply/mdf, use a fat bead of PL Premium.
2. Make a similar cutout to the bottom of the second enclosure, but only remove the port and block its hole, leave drivers in place. With a fat bead of PL Premium, glue both enclosure together and you have a box of 2x Vb that might get a bit of quarterwave action. Use a 3" or 4" ABS pipe vent close to the bottom of the enclosure to experiment with tuning, start long and gradually trim-off until satisfactory.
At this point, you should have a fair enough idea if it's worth your time/$$ to build two proper enclosures of similar dimensions to the franken-MLTL.
I don't know about this Foster horn, but I used to have a pair of 49-1168 from an Allegro 1000 and these were pretty good used with a 1µF capacitor as a helper tweeter with large fullrange drivers.
1. Use a jigsaw/sawzall to remove a large section of the top or bottom of one enclosure. Remove drivers and port. Block the driver/port holes with cutout panel and scrap ply/mdf, use a fat bead of PL Premium.
2. Make a similar cutout to the bottom of the second enclosure, but only remove the port and block its hole, leave drivers in place. With a fat bead of PL Premium, glue both enclosure together and you have a box of 2x Vb that might get a bit of quarterwave action. Use a 3" or 4" ABS pipe vent close to the bottom of the enclosure to experiment with tuning, start long and gradually trim-off until satisfactory.
At this point, you should have a fair enough idea if it's worth your time/$$ to build two proper enclosures of similar dimensions to the franken-MLTL.
I don't know about this Foster horn, but I used to have a pair of 49-1168 from an Allegro 1000 and these were pretty good used with a 1µF capacitor as a helper tweeter with large fullrange drivers.
Last edited:
I may be in a minority of one here, but I am disturbed at the direction this thread is taking.
IMO, most improvement will come from giving the free running bass a filter. I've never heard a 8" or 10" paper bass that sounds particularly good without a filter. It just lets harsh cone breakup through.
That Zenith Allegro box looks like your typical chipboard box. No objections to it really, it's cheap, it works, we know how to apply panel damping and volume damping if you want to do better.
I really don't know if reflex helps the cause here. Depends on the driver parameters. Maybe an aperiodic (damped) port is required.
I would use the Zenith box as a test cabinet. Not hard to get the bass out with a couple of cheesewedge cuts on the edge of the bass hole. You can then glue the wedges back in easily enough. 10" bass is going to want about 40-50L regardless.
This sort of 10" bass plus low crossover (1-2 kHZ) tweeter must make compromises at the very top end, but has something if you can find a tweeter driver that can handle 2kHz. Most of the classic 10" two ways used a second order bass filter around 2kHZ with a 3kHz tank notch.
IMO, most improvement will come from giving the free running bass a filter. I've never heard a 8" or 10" paper bass that sounds particularly good without a filter. It just lets harsh cone breakup through.
That Zenith Allegro box looks like your typical chipboard box. No objections to it really, it's cheap, it works, we know how to apply panel damping and volume damping if you want to do better.
I really don't know if reflex helps the cause here. Depends on the driver parameters. Maybe an aperiodic (damped) port is required.
I would use the Zenith box as a test cabinet. Not hard to get the bass out with a couple of cheesewedge cuts on the edge of the bass hole. You can then glue the wedges back in easily enough. 10" bass is going to want about 40-50L regardless.
This sort of 10" bass plus low crossover (1-2 kHZ) tweeter must make compromises at the very top end, but has something if you can find a tweeter driver that can handle 2kHz. Most of the classic 10" two ways used a second order bass filter around 2kHZ with a 3kHz tank notch.
Thanks for the reminder! Anything to save time/$$$. These days, this is way too obvious for me to think of it and yet use to do it even with quality built cabs. 🙁 FWIW, I used cardboard mailing tubes, though I imagine they're not nearly as plentiful these days for free now that most pictures, drawings, etc., are digital transferred.
They looked to be about 2 ft tall, if so, then long enough too get some minor TL action going on and it would put the woofer down in the optimal 0.33-0.4 offset range and locating the vent ~6.5" i.d. up from the bottom.
GM
They looked to be about 2 ft tall, if so, then long enough too get some minor TL action going on and it would put the woofer down in the optimal 0.33-0.4 offset range and locating the vent ~6.5" i.d. up from the bottom.
GM
I can see a bit of crossposting there, but the modern equivalents of this sort of speaker are the SEAS A26, which was a Dynaco A10 clone really, and the DeVore Orangutan:
TBH, a three way makes more sense, but we all like trying stuff. 🙂
I used to have a speaker of this type called the Wharfedale Melton:
It was quite good. Plunky sort of sound. Really OK, though not the last word in wide dispersion.
An externally hosted image should be here but it was not working when we last tested it.
TBH, a three way makes more sense, but we all like trying stuff. 🙂
I used to have a speaker of this type called the Wharfedale Melton:
An externally hosted image should be here but it was not working when we last tested it.
It was quite good. Plunky sort of sound. Really OK, though not the last word in wide dispersion.
Last edited:
Well I can build about anything out of wood quite well, but this being my 1st DIY I don't understand where the filter would go in relation to the xover. Once I decide on what to do with the cabinet I may have to reach out to one of you more knowledge fellas. I also do not know how to "tune" a speaker
Last edited:
But it is so cheap that it does not work. Cheaper & easier to build a new box than to try to patch up the original. Older ones were a bit better (still junk), but this one with no way in is real trash.
That from experience... at least 10 pairs.
dave
I will get into the cabinets tomorrow and see what I find. For some reason I want to see what's in there
