Also check Erse (Premium grade audio components including crossover inductors, audio capacitors, electronic assemblies | ERSE Audio) for crossover parts. Their prices are reasonable, and shipping isn't prohibitive to Canada.
Box measures 6.75 in on outside, so it's made of 3/8" particle board which is thinner than the box. Mine is very crudely made with poor fitting butt joints which I am sure makes it subject to influence from the bass driver.
I'm planning on replacing the front baffle on my 44s to remove the lip, and with the new baffle, fit a section of sonotube, ported with a variovent, for the mid driver.
Ahh thanks so much for doing that, I really appreciate it. That helps a lot, now I can get the exact dimensions I need for the boxes.
I agree, I noticed on one of my old 44s the midrange driver moved in and out with the bass driver. I imagine this is causing coloration to the midrange.
This may help with the woofer box:
From a CELESTION service-sheet, in german.
HiFi Bass-Systeme
12" T 2619 30,4 cm
Celestion Application Ditton 44, Ditton 25, Ditton 66
Resonanz 20 Hz
Frequenzbereich 20 Hz bis 2 KHz
Poldurchmesser 1,75" (44 mm)
Empfohlene Übergangsfrequenz 500 Hz bis 1 KHz
Magnet 1,14 Tesla (11400 Gauss 128000 Maxwell)1280 µWb
Belastbarkeit 80/160 Watt DIN 45500
20 Volt Sinus von 20 Hz bis 500 Hz
From a CELESTION service-sheet, in german.
HiFi Bass-Systeme
12" T 2619 30,4 cm
Celestion Application Ditton 44, Ditton 25, Ditton 66
Resonanz 20 Hz
Frequenzbereich 20 Hz bis 2 KHz
Poldurchmesser 1,75" (44 mm)
Empfohlene Übergangsfrequenz 500 Hz bis 1 KHz
Magnet 1,14 Tesla (11400 Gauss 128000 Maxwell)1280 µWb
Belastbarkeit 80/160 Watt DIN 45500
20 Volt Sinus von 20 Hz bis 500 Hz
From the inside lip of the bottom panel to the centre of the bass driver is 225mm.
From the inside lip of the bottom panel to the centre of the mid driver is 485mm.
From the inside lip of the bottom panel to the centre of the tweeter is 640mm.
The inside lip of the bottom panel is essentially the inside of the panel, which is crappy 1/2" chipboard, nicely veneered
so I measured from the inside, as I guess you'll be going for a bit thicker than 12.5mm panels....
From the inside lip of the bottom panel to the centre of the mid driver is 485mm.
From the inside lip of the bottom panel to the centre of the tweeter is 640mm.
The inside lip of the bottom panel is essentially the inside of the panel, which is crappy 1/2" chipboard, nicely veneered
so I measured from the inside, as I guess you'll be going for a bit thicker than 12.5mm panels....
Yeah no kidding! They aren't even braced or damped very well. I imagine the revitalized crossover, better damping and cabinets are going to make some important improvements. Not to mention the isolated drivers.
I think this is going to turn out to be quite the speaker!
Many thanks for all your help, I think I have all the measurements I need now to get this started. Now it's just a matter of getting the mids here, then I am going to have a dummy pair of cabinets build to try it out.
I will keep you posted.
Just trying to wrap my head around something.. if the inside depth is 6.25, and the outside measures 6.75, doesn't that mean its 0.5" thick?
Sorry if I wasn't clear. What I meant is that the 6.75 inches is the outside of the width (horizontal) and height (vertical) of the mid box. By depth I meant the inside dimension from the inside of the baffle to the the inside of the back of the mid cabinet. Then, since the inside vertical and horizontal dimensions where 6 inches, you have 3/8" thick mid cabinet walls. Hope that helps?
Ohh now that makes sense. Thanks.
Now the next step is to get the volume of the cabinet for just the bass.. won't be tough now.
Is it possible to derive a cabinet size from the volume?
Now my turn to be confused. Don't you have measurements for the cabinet, so why derive it?
I want to subtract the midrange enclosure from the inside of the cabinet. My plan is to put the midrange in its own enclosure on top of the cabinet for the bass driver.
So, I want to take the volume of the cabinet minus the midrange enclosure and build a cabinet for the bass driver with that volume so it remains the same.
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I wouldn't worry about it.
If I recall correctly, the Fs of the bass driver is in the vicinity of 20 hz, so subtracting the mid volume from the cabinet will have a very small consequence on the resonance of the cabinet. And the effect it will have, is to lower the resonance (by a very small amount. And probably no more than the variance in driver specs.)
If I recall correctly, the Fs of the bass driver is in the vicinity of 20 hz, so subtracting the mid volume from the cabinet will have a very small consequence on the resonance of the cabinet. And the effect it will have, is to lower the resonance (by a very small amount. And probably no more than the variance in driver specs.)
For what it's worth - I think if you can redesign the crossovers with less caps, it's a good idea. I have some 442s and there were a plague of caps to degrade the signal, I replaced them all with expensive solen caps and there was no improvement at all. Then swapped the entire crossover for a set nicked from some B&W, fewer caps better sound. Next flaw is the cabinet, agree with you there, having upgraded my amp I am able to hear the reflections from the box coming through the cones. Damping is virtually useless for limiting LF so it's extra bracing or 18mm ply. Lucas is right about the tweeter, seas is a DEFINITE upgrade.
I'm going full range and building some boxes around MA 12m SO HAD IT with crossovers
Also - if you like snake oil, have a look at the EnABL process. Apparently the science is sound and people swear by it. I'm going to trial it on my 442's will let you know.
I'm going full range and building some boxes around MA 12m SO HAD IT with crossovers
Also - if you like snake oil, have a look at the EnABL process. Apparently the science is sound and people swear by it. I'm going to trial it on my 442's will let you know.
Lorien and I have had many adventures with these Ditton 44s. We have taken quite different approaches, and I have to say I think I was more successful, mostly because I didn't try to change anything too drastically, but slowly refined things, whereas Lorien, as he has said, changed the entire crossover, the drivers several times etc., most of which didn't really work wonders as it was highly experimental and sometimes hard to work out what was going on. I had a lot of help from alanb1 on the 66 thread. This has lead Lorien to throw in the towel with crossovers and go full range, not without good reason, if reports of the Mark Audio drivers are to be believed!
Although I like the "idea" of the bass driver crossover being a simple cap and an inductor, in reality that will affect the sound a lot, and I think this crossover design is a big part of what I like about these speakers. My advice is to keep the design, all the values, and only add resistors to replace ESR and to balance the sound.
Lorien, I don't think that the crossover caps significantly degrade the signal. I think the design and values affect the smoothness of the frequency response, which is the key thing. I find in Hifi, the real snake oil is for those that don't understand what they're doing and spend money on esoteric stuff with unfathomably subtle effects, like pricey silver interconnects, whilst their crossover resistor values are wrong, or they buy Mundorf gold caps when simply getting the value right in almost any cheap cap would bring the real improvement. I have learnt by being this idiot a few times in the past, until Nelson Pass and others put me on the right track.
Although I like the "idea" of the bass driver crossover being a simple cap and an inductor, in reality that will affect the sound a lot, and I think this crossover design is a big part of what I like about these speakers. My advice is to keep the design, all the values, and only add resistors to replace ESR and to balance the sound.
Lorien, I don't think that the crossover caps significantly degrade the signal. I think the design and values affect the smoothness of the frequency response, which is the key thing. I find in Hifi, the real snake oil is for those that don't understand what they're doing and spend money on esoteric stuff with unfathomably subtle effects, like pricey silver interconnects, whilst their crossover resistor values are wrong, or they buy Mundorf gold caps when simply getting the value right in almost any cheap cap would bring the real improvement. I have learnt by being this idiot a few times in the past, until Nelson Pass and others put me on the right track.
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For what it's worth - I think if you can redesign the crossovers with less caps, it's a good idea. I have some 442s and there were a plague of caps to degrade the signal, I replaced them all with expensive solen caps and there was no improvement at all. Then swapped the entire crossover for a set nicked from some B&W, fewer caps better sound. Next flaw is the cabinet, agree with you there, having upgraded my amp I am able to hear the reflections from the box coming through the cones. Damping is virtually useless for limiting LF so it's extra bracing or 18mm ply. Lucas is right about the tweeter, seas is a DEFINITE upgrade.
I'm going full range and building some boxes around MA 12m SO HAD IT with crossovers
Also - if you like snake oil, have a look at the EnABL process. Apparently the science is sound and people swear by it. I'm going to trial it on my 442's will let you know.
I'm surprised the capacitor change didn't do much for you on the 442s. On all the speakers I've recapped (IMF TLS 80 IIs, IMF RSPM Mk IVs, IMF Super Compacts, Kef 104/2s, Kef 107s, IMF Pro Monitor MK1, Celestion Ditton 25, and so on) it has always made a substantial improvement. I don't use Solen or any boutique caps either, I use Alcap capacitors. Reason being that they are the closest thing to the original (and are likely even better quality these days), so I don't like to change gears. But, in my experience, they have always made a big improvement. The Celestion Ditton 25s made the biggest improvement. And I don't recap both at once, I recap one, and then compare it to the original so I know I'm not just hearing it because I spent the money.
Anyway, I don't think capacitors are your culprit at all, I think it's something else.
Of interest to you, you may want to look into charge coupled crossovers. I have a pair of IMF Super Compacts with charge coupled crossovers, and I have another pair of Super Compacts that are all original, the difference was substantial! Both are recapped so that is equal, but the charge coupled model sounds far more natural and musical. It's like the sound was electrified. Do some research on it, I think you'll be impressed. It's a good way to improve electrolytic caps in a crossover.
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