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Multi-Way Conventional loudspeakers with crossovers

1970's TL remake help
1970's TL remake help
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Old 3rd March 2018, 05:15 PM   #1
webby is offline webby  United Kingdom
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Default 1970's TL remake help

Hi All,
Due to family life my large Open Baffle speakers have to go.
I am going to try remaking these 1970's Cambridge Audio R50 copies.
They have the usual Kef 3 way drivers. and the cabs are in good shape, except for the front baffle. They need to be remade so i was thinking I would keep the B139 for bass and the use some TC9FD-18-08 for mid, and better tweeter, keeping them a three way.
I have 2x4 Mini DSP and Umik Mic and a few different amps.
The baffle are recessed about 15mm into the cabinet and must have a negative effect on the sound, and against current thinking. I have some 33mm Formica birch ply that would flush mount nicely.
I have been using the Vifa TC9FD-18-08 and am impressed, so would like to continue using them.

Would you put the vifa TC9FD-18-08 in the current Mid enclosure that is within the cabs, or would it be better to locate the mid and tweeter drivers closer together and ear height, any thoughts?
What about removing the Mid enclosure, might be an opportunity to improve the TL?

Any thoughts on using the other mini DSP channel either the TC9FD-18-08 or the tweeter? I will need to used one with a passive crossover.

I have a pair of Vifa D25AG-05-06 on hand, or maybe better to use a smaller tweeter to get close spacing to the TC9FD-18-08.

Here are the design details and photos.
Any help or suggestions, I would be very grateful.
Thanks
Ian
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Old 3rd March 2018, 05:46 PM   #2
multisync is offline multisync  Canada
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I have and still use the same speakers. I took then to a local diy audio event a couple of years ago and the general feeling was they sound pretty da#* good for 40 year old speakers.
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Old 4th March 2018, 08:52 AM   #3
webby is offline webby  United Kingdom
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I like how they sounded but they are not very good at imaging / sound staging, and I'm coming from open baffle that are excellent in that regard.
Trying to minimise the step back to boxed speakers.

So, any ideas?
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Old 8th March 2018, 01:57 PM   #4
webby is offline webby  United Kingdom
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Can anyone help make a guess if it would be better to put the TC9FD-18-08 in the existing mid enclosue, its about 9.8 litres.
Just not sure if it will sound good in that low down position, I'm used to them being at ear height.

Any suggestions please?
Many thanks
Ian
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Old 8th March 2018, 03:36 PM   #5
system7 is offline system7  United Kingdom
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webby, I think you have this all wrong. You can't replace a 5" mid with a 3.5" fullrange one and get enough loudness.

Click the image to open in full size.

Looks like a Celestion HF2000 tweeter, if not KEF T27, and a B110A or B midrange.

I don't think you can go far wrong to get it back to original spec. Bit of a research project, but Falcon Acoustics and Wilmslow Audio offer off-the-shelf crossovers for this model, IIRC.

The old B139 bass is getting a bit long in the tooth, IMO. With a conveniently removeable baffle, you can surely fiddle around a bit on more modern basses.

What I would do, is trace the crossover for your 3-way unit. Maybe consider getting back to 4-way with the still available Coles supertweeter.

Schematics are still available. This will be a labour of love, but I think doable. I wouldn't think it is rocket science to use a more modern mid as well. The Peerless 830860 can't be way different. Peerless HDS PPB 830860
Attached Images
File Type: jpg Cambridge R50 speaker.JPG (36.7 KB, 54 views)
File Type: jpg Cambridge R50 Speaker Crossover.JPG (58.3 KB, 82 views)
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Last edited by system7; 8th March 2018 at 03:40 PM.
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Old 8th March 2018, 04:18 PM   #6
boswald is offline boswald  United States
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1970's TL remake help
If you need more output, or want a closer to drop in shape, Peerless has brought back the alloy frame version of that shape(over here PE has it- look up 5 1/4" Classic).
Easy to use- look at that response graph.

The only way to make a 3.5 work here is to go mtmw, double 'em up to get max spl.

Last edited by boswald; 8th March 2018 at 04:21 PM.
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Old 8th March 2018, 04:58 PM   #7
system7 is offline system7  United Kingdom
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Boswald, you are a wise old cove. It is, of course possible to replace a big mid with two smaller units.

This was done before in the Celestion 25 and the Wharfedale E70 below.

Click the image to open in full size.

Both fine speakers. Thing is you gain 6dB loudness from doubled drivers. Which reduces distortion.

IMO, speakers are all about the mids. Voices if you like.

Here's a fun way of doing things. The dispersion of the woofers matches the ribbon tweeter:
Click the image to open in full size.

It's not all about frequency response. Room acoustics and dispersion comes into it.
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Old 8th March 2018, 05:47 PM   #8
drewan is offline drewan  United Kingdom
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Falcon acoustics were and could still be selling the B110, celestion and coles drivers, as well as crossover kits
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Old 9th March 2018, 03:57 PM   #9
webby is offline webby  United Kingdom
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Thanks for the ideas so far.
When I had them setup as standard they lacked bass in my room, they also didn't do the sound stage / imaging thing very well. The baffles might be to blame not being airtight, the t nuts have chewed the chip board, it may be the crossovers, I'm not sure. Didn't want to spend much cash and wanted to utilise what I have.
So a new baffle / drivers and 2 active channels out of three sounded fun.
Would two tc9's in the mid enclosure work?
Many thanks
Ian
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Old 9th March 2018, 04:37 PM   #10
boswald is offline boswald  United States
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1970's TL remake help
Take off the baffle, measure the insides, and give us a photo. Then we'll see what can fit where.
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