.... I have better enjoyment with it slightly duller up top.
Hi Simon,
I'm not sure if I brought this up already, but I think it's about time (for you) to try back-firing tweeters.
Feel free to try any tweeters (for experiment, at least). Adjust it's level to get similar frequency responses from front and back. Because of the physical size of your baffle and WG, it'd never make a perfect dipole polar pattern in the HF, but rear firing tweeter still help in overall tonal balance.
Once your tonal balance of rear radiation is properly set, you'll get a sound that is never dull or bright. It'll be natural. 😀
Have fun.
CLS🙂
interesting/excellent project dude, i'm also living in sheffield and like to build speakers. Until recently i've been mainly interested in building PA systems, my current system is actually the same set up driver (size) wise for the mid tops, two 12" beyma sm112n in a reflex cabinet, eminence 8mr sealed back 8 on a horn and a B&C de250 on an 18sound oblete spheroid waveguide. Also got some beyma 12lx60 drivers that i was using in modified decware wicked ones. old system pic http://i300.photobucket.com/albums/nn7/danger_noise/tinnitus20508114.jpg
it's been painted since and is generally more strapped together
thinking about it i've also got some celestion ubermini 1" neodymium compression drivers that are earmarked for some 12 and 1 monitors kicking around that may be worth a shot as they're only about 30 quid a go and sound quite sweet. http://professional.celestion.com/pro/pdf/CDX1-1425.pdf
If you're interested in comparing some of these sometime in the new year (particuarly the comp drivers which may well prove easier to mount) i'm well up for it. Always good to meet more local speaker geeks to talk audio with, specially if you get to hear new stuff in the process 🙂
Hi Rich,
Brilliant, good to hear from you. I'd love to meet and hear some of this stuff, I'm particularly interested in hearing those B&C tweeters as those are the model Earl Geddes uses in his designs (or at least recommended) with OS waveguides. These Eminence ones are usable but they're behind the mid and bass quality I have in this system.
It looks like a dangerous wall of sound in that picture, I bet it goes LOUD! Do you make systems for pubs and clubs or just massive parties?!
Simon
Hi Simon,
I'm not sure if I brought this up already, but I think it's about time (for you) to try back-firing tweeters.
Hi CLS!
It's really interesting you should mention this now, the timing of it... as just about a week or two ago I did my first experiments with rear-firing tweeters. I was dismantling my mk1 open baffles to store the parts and so had some cheap Wharefedale soft domes to hand. I gaffa-taped them to the back of the speakers and fed them through a randomly bodged cap and L-pad. I'm not sure I'm convinced, it made the sound less defined and more coloured. I will be sure to try again and do it more carefully with a better-selected crossover point and stronger attenuation.
I think, in theory, it could be a bad thing to use in a tiny bedroom though. In a large living room with the speakers a good distance from the back wall and equidistant from the side walls there is surely much more merit in using rear tweeters. In my system I fear the effect will not be as advertised! That won't stop me trying, of course.
Simon
Maybe I need to use compression tweeters front and rear to maintain a similar "tone/presentation". I find all silk tweeters to sound sweet and soupy, basically all with similar colouration or lack of dynamic ability. So far I don't like compression drivers either, but I do need to hear more. (Wish I'd just bought some cheap ribbons, would've been much easier!!!!)
I think you will definitely like the de250's they're a very very sweet compression driver. What frequency are you crossing over between the comps and the 8's? would go look as im sure its in the thread but can't really be bothered searching through 40 or so pages 🙂
I have a slight feeling that if the x-over is higher than 3k the little celestion neo's may be slightly brighter up top due to the metallic diaphragm. The real bonus of the De250s is that they sound very smooth down to 2.2k if required.
I notice you saying thus far you're not impressed with comp drivers, i think if you used the specified eminence horn for the apt50's the sound would improve due to the odd termination of the driver exit and phase plug making the correct horn pretty much compulsory. Any deviations in the transition from the driver exit to the horn/waveguide will seriously degrade the response. Many moons ago the de250s (1 inch exit) were mounted in some old yamaha mid top cabs, the horn in them was a .75" entry horn. Made for a hugely slicey top end, awesome for techno high hats, no so good for more subtle recordings 🙂
I also got to wondering if you had conisdered mounting the woofers in a push pull configuration? I made some double 12 bass cabs that were push pull and the sound they produced was incredibly clean.
Going to be busy for the next couple of weeks but eager to meet up and have a listen to stuff after that, are you on facebook or msn at all?
I have a slight feeling that if the x-over is higher than 3k the little celestion neo's may be slightly brighter up top due to the metallic diaphragm. The real bonus of the De250s is that they sound very smooth down to 2.2k if required.
I notice you saying thus far you're not impressed with comp drivers, i think if you used the specified eminence horn for the apt50's the sound would improve due to the odd termination of the driver exit and phase plug making the correct horn pretty much compulsory. Any deviations in the transition from the driver exit to the horn/waveguide will seriously degrade the response. Many moons ago the de250s (1 inch exit) were mounted in some old yamaha mid top cabs, the horn in them was a .75" entry horn. Made for a hugely slicey top end, awesome for techno high hats, no so good for more subtle recordings 🙂
I also got to wondering if you had conisdered mounting the woofers in a push pull configuration? I made some double 12 bass cabs that were push pull and the sound they produced was incredibly clean.
Going to be busy for the next couple of weeks but eager to meet up and have a listen to stuff after that, are you on facebook or msn at all?
Hi,
I don't know how I missed this post before, but I did!
A bit late I guess but... I cross the tweeters at about 5khz, leaving the mids to go as high as they possibly can.
The reason I came back here is because I just tweaked my waveguides a little bit (throat area) to be smoother and when I put things back one of the APTs sounded completely different - much louder and as if no crossover filter is applied ie. midrangey. I've tried both tweeters on one speaker to test and it's definitely the driver itself.
It's bizarre, the thing measures 5.7DCR, same as the other and doesn't appear to be physically damaged. It just started sounding completely different and it really draws attention to itself. I guess I'll have to replace it but what has happened here?! I'm stumped.
Simon
ps - Rich, if you're still about I'd like to meet up!
I don't know how I missed this post before, but I did!
A bit late I guess but... I cross the tweeters at about 5khz, leaving the mids to go as high as they possibly can.
The reason I came back here is because I just tweaked my waveguides a little bit (throat area) to be smoother and when I put things back one of the APTs sounded completely different - much louder and as if no crossover filter is applied ie. midrangey. I've tried both tweeters on one speaker to test and it's definitely the driver itself.
It's bizarre, the thing measures 5.7DCR, same as the other and doesn't appear to be physically damaged. It just started sounding completely different and it really draws attention to itself. I guess I'll have to replace it but what has happened here?! I'm stumped.
Simon
ps - Rich, if you're still about I'd like to meet up!
The problem could actually be on the one I thought was normal (which I have dropped and damaged before), but that wouldn't explain why they sounded more or less identical until now.
Hi Ricardo,
The difference is narrowed down to the diaphragm / phase plug / voice coil. I have directly compared the tweeters and these parts of the tweeter, by swapping it to the other magnet and vice versa.
Simon
The difference is narrowed down to the diaphragm / phase plug / voice coil. I have directly compared the tweeters and these parts of the tweeter, by swapping it to the other magnet and vice versa.
Simon
Last edited:
Ok, I don't know why I didn't notice this as much before but I think actually the faulty one is the OTHER one, the quieter, less midrangey one. I think when I dropped it and broke off the phase plug, the super glue I used to put it back in place has corrupted or reduced movement of the diaphragm. I think I need a new tweeter and then to do some measurements to make sure I have two doing the same job. I'll then re-check my crossover design and go from there. How silly of me!
No wonder I've never been satisfied by the top end lol
No wonder I've never been satisfied by the top end lol
Oh and all this sticking the diaphragm to the faceplate (yes, I've just discovered the glue seeped in and did that) would explain my odd top end response that didn't match people's expectations, as well as the low efficiency I've seen in those measurements and by ear. I did all my measurements with the dropped and glued tweeter as far as I can tell. This looks bad but it's best to be honest about it, for the sake of those who've helped me or watched me make these speakers 

Never be afraid to explain the truth.
In the end that is what counts.
i always try to do the same 🙂
In the end that is what counts.
i always try to do the same 🙂
Good man 🙂
Well I've torn off the phase plug and removed the excess super glue and tried to glue it back on more carefully. At the moment they sound about the same as each other! Looks like I have some answers now. Ultimately I could do with a replacement tweeter but I'll see how this one sounds now when the glue's dried.
Well I've torn off the phase plug and removed the excess super glue and tried to glue it back on more carefully. At the moment they sound about the same as each other! Looks like I have some answers now. Ultimately I could do with a replacement tweeter but I'll see how this one sounds now when the glue's dried.
Last edited:
OK, bit of wiggling and it's back to ok now. I need to measure these, see how different they are. I'm reluctant to buy a new tweeter only to upgrade as soon as possible.
I've had to turn down my mid/treble amp to compensate for this renewed top end. Lots of tweaking to do!
I've had to turn down my mid/treble amp to compensate for this renewed top end. Lots of tweaking to do!
Hi SimontY,
I have bin looking at the circuit of the woofers with the transformer. And I do not understand how it works can you explain it.
I see a cut-off of the coil at 70Hz I guess what happens when the 8,2mH is low impedance.
And I see a second order 12mH and 150uF normal second-order steepness.
What is the function of the transformer?
I have bin looking at the circuit of the woofers with the transformer. And I do not understand how it works can you explain it.

I see a cut-off of the coil at 70Hz I guess what happens when the 8,2mH is low impedance.
And I see a second order 12mH and 150uF normal second-order steepness.
What is the function of the transformer?
hi again simon, regards your tweeter issues id recommend looking at celestions cheaper offerings. I have their neo top end drivers in some wedge monitors and they sound excellent even when being run pretty loud, at hifi levels they would be lush. http://professional.celestion.com/pro/pdf/CDX1-1425.pdf only about 25 squid a pop too.
still up for meeting up for a listening sesh, drop me a pm and can arrange from there...
still up for meeting up for a listening sesh, drop me a pm and can arrange from there...
- Status
- Not open for further replies.
- Home
- Loudspeakers
- Multi-Way
- 3 way open baffle with Eminence and Skytronic