This is a rare pair of Expert Acoustic Column (formerly EMG) cabs, c. 1960, I am restoring. Originally fitted with Baker Selhurst 12" + Lorenz cone tweeter filtered by a 2 uF cap.
I am very hazy about modern drivers and I am seeking advice on what to buy. Currently I have fitted Kef B200s and cheap Peerless tweeters + a simple 1st order x-over to try them out - very nice too!
I assume the cab with its two vents at the bottom was optimized for 12" drivers, so I am looking for something with a low rf and reasonably good MF performance. As for a tweeter - something that sounds like the old Celestion HF 1300 would be nice - physically small as it will be mounted over the 12" driver. Suggestions very welcome.
I am very hazy about modern drivers and I am seeking advice on what to buy. Currently I have fitted Kef B200s and cheap Peerless tweeters + a simple 1st order x-over to try them out - very nice too!
I assume the cab with its two vents at the bottom was optimized for 12" drivers, so I am looking for something with a low rf and reasonably good MF performance. As for a tweeter - something that sounds like the old Celestion HF 1300 would be nice - physically small as it will be mounted over the 12" driver. Suggestions very welcome.
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If you want to keep the cabinet ported as is, an overall cabinet volume and tuning frequency might help people suggest a suitable driver.
Is there a budget or is cost no object?
In standard woofers, you're going to be asking a lot of both drivers to get a small dome tweeter and a 12" woofer to play nice together. Many larger woofers that are optimized for low frequency performance have very ragged upper midrange response. Careful selection will be important. You'll probably have to give up some midrange detail in exchange for smoother high frequencies from the woofer. Something with a doped paper or polypropylene cone is probably in order.
I'm not familiar with the Celestion HF 1300, but the Peerless/Tymphany OX20SC00-04 is one of the smallest dome tweeters with a relatively low resonance that I've come across.
Peerless by Tymphany OX20SC00-04 3/4" Fabric Dome Tweeter
Is there a budget or is cost no object?
In standard woofers, you're going to be asking a lot of both drivers to get a small dome tweeter and a 12" woofer to play nice together. Many larger woofers that are optimized for low frequency performance have very ragged upper midrange response. Careful selection will be important. You'll probably have to give up some midrange detail in exchange for smoother high frequencies from the woofer. Something with a doped paper or polypropylene cone is probably in order.
I'm not familiar with the Celestion HF 1300, but the Peerless/Tymphany OX20SC00-04 is one of the smallest dome tweeters with a relatively low resonance that I've come across.
Peerless by Tymphany OX20SC00-04 3/4" Fabric Dome Tweeter
Another question: how much output/power handling do you need?
A weirder idea would be to use something like this for the higher frequencies:
Dayton Audio ND64-4 2-1/2" Aluminum Magnesium Cone Full-Range Neo Driver 4 Ohm
In about 7 cubic inches, excursion is well controlled into the midrange. Power handling isn't fantastic (30 watts), and neither is sensitivity (85 dB), but the sound is pretty good for a small "full-range." I've been using them in some PC speakers, so my power requirements are low. I haven't tried them at more typical listening distances.
Very high frequencies are lacking a bit of air/refinement, as is typical of many full-range drivers, but I find them acceptable.
A weirder idea would be to use something like this for the higher frequencies:
Dayton Audio ND64-4 2-1/2" Aluminum Magnesium Cone Full-Range Neo Driver 4 Ohm
In about 7 cubic inches, excursion is well controlled into the midrange. Power handling isn't fantastic (30 watts), and neither is sensitivity (85 dB), but the sound is pretty good for a small "full-range." I've been using them in some PC speakers, so my power requirements are low. I haven't tried them at more typical listening distances.
Very high frequencies are lacking a bit of air/refinement, as is typical of many full-range drivers, but I find them acceptable.
Thanks - I really need a 12" driver to try to get close the original sound. Power isn't an issue - the amp is a Radford STA12 (12W) stereo valve amp - also from 1960. That tweeter looks a bit more sophisticated than the ones I have - but how do you fit it? There doesn't seem to be a mounting?
If you are going to use low power, do you need high sensitivity though? That's a decision point as well.
I'm not sure if you misinterpreted my previous post. My point with the 2.5" was that it could cover midrange and up when used with a 12" woofer. That would relax the requirement of higher midrange performance from the 12", which would give you more options. Again though, if you need high sensitivity this route is less relevant, since most small full-range drivers have relatively low sensitivity.
On the ox20 mounting:
There is a small flange molded into it that you can use to secure it to a small mounting plate/baffle. If you don't want a small baffle, you can mount the tweeter with 2-sided tape, glue, etc. However you do it, you'll have to make those bits. It's very small and pretty light, so it doesn't need much structure to mount it.
A few examples of how other people have handled mounting:
Vifa OX20 how to mount? — MAC/DIY
The January 3, 2010 post near the bottom discusses mounting.
Zaph|Audio
There's also a similar version that has small ears on the flange. With those you could do a twist lock.
Peerless OX20SC02-04 20mm Fabric Dome OX Tweeter 4 Ohm
I'm not sure if you misinterpreted my previous post. My point with the 2.5" was that it could cover midrange and up when used with a 12" woofer. That would relax the requirement of higher midrange performance from the 12", which would give you more options. Again though, if you need high sensitivity this route is less relevant, since most small full-range drivers have relatively low sensitivity.
On the ox20 mounting:
There is a small flange molded into it that you can use to secure it to a small mounting plate/baffle. If you don't want a small baffle, you can mount the tweeter with 2-sided tape, glue, etc. However you do it, you'll have to make those bits. It's very small and pretty light, so it doesn't need much structure to mount it.
A few examples of how other people have handled mounting:
Vifa OX20 how to mount? — MAC/DIY
The January 3, 2010 post near the bottom discusses mounting.
Zaph|Audio
There's also a similar version that has small ears on the flange. With those you could do a twist lock.
Peerless OX20SC02-04 20mm Fabric Dome OX Tweeter 4 Ohm