Tannoy CPA 12 Cabinets

looking great !! would love to hear them.

where is a good place to get birch ply cut to size then delivered ?

 

Been busy today.

 

You're welcome to, if you are ever in Ilford give me a shout.

 

Looks excellent Dev and I'm looking forward to hearing them on Sunday.

 

Hi Dev,

Looking good.

SCIDB

 

super cabs dev, are you going to varnish them?

 

Great Dev, very nicely put together.
How do they sound?

Cooky

 

No, I'm going to veneer them, eventually.

Initial impressions are good, to my ears. CPA12s finally have some bass. I've just plonked them about a meter apart and connected them to Crown K2 and iPod and I think Deep Purple, Led Zeppelin and Leftfield sound great. With certain classical music something seems to be missing. Rob's coming over tomorrow for some critical listening. I think they'll sound better (soundstage should improve) when I move the D700s out of the way and put some distance between the speakers and toe them in slightly.

 

Great time at Dev's today listening to the new beasts, swapping amps and teasing out packs of fluffy lambs wool <cough wheeze>

The pictures don't do these cabinets justice and i can't see how Dev (or Tannoy) could have made a better sealed box of this size.

Scale and bass are superb. The cabinet transforms what this driver can do and I though it performed superbly on reggae.
The driver/crossover combo is however very brightly lit and the speaker can harden up and shout without much encouragement. We'll know more when we measure it next week, but the presence range is well boosted to my ears.
Should be correctable with some crossover mods though.

The amp swapping was interesting. We began with them running from a monster Crown K2 pro amp and this wasn't good at all. Overdamped and hard with a glassy upper mid.
Moving to an A&R A60 or Dev's much underrated (by him) Gainclone things clearly improved. It would be interesting to look at the distortion performance of the K2 when not working hard (as here).

Dev's valve Rogue amp will likely mellow things further but from what I heard today these showed huge promise.

 

Looking good Dev, dump the grills and use spacers for the bolts, the grills fairly sing along.

 

Did exactly that on Sunday Simon. I prefer them without grills to be honest but just wanted something to keep inquisitive fingers away from drivers. I may look at grills later, if the other half complains about naked drivers.

 

Looking really good Dev.
How do they compare sound wise with what you heard at my place with the the drivers in the full size GRF's?

 

I think they sounded better in your cabinets, they weren't as bright. With Raggae music, for example, they sound great, but overall, some work is needed on the crossover to tame the HF.

 

Thank goodness for that!
There should be some benefit however small to the big cab approach and all that backloadedness.
That said I am sure you can tune them up with crossover tweaks.

 

If the HF section is 1st order how I remember you can drop a 5-7 ohm resistor in series with the tweeter to drop that HF section a tad.
Rob's your man tho' in this regard.

 

An L-pad tweak is what's needed to keep the ohms as seen by the amp the same - there will already be one in HF the crossover as the Tannoy horn upper mid / tweeter is much more efficient than the radiator cone.

I have found this calc prog excellent (right at the bottom for the L-Pad stuff).
http://ccs.exl.info/calc_cr.html

2 or 3 dB is subtle but noticeable.

I get the resistors and other component bits from this local place - who have given good service with my custom.
http://www.audio-components.co.uk/

 

Actually Steve these are the tulip waveguides not the pepperpot CD horns they use the same HF as the 15" and with no resistor in series at all they run hot at + 1.5dB, 1.4 ohm is flat, 2.7 ohm -1.5 db. Even at -1.5 I find them bright.

 

That's good to know.

I guess the brightness depends on what they are working with - I would not have said they were particularly bright when we tried them in the GRF's but there they are working with a ~6dB lift of the below 1000Hz woofer from the backloaded horn.
In a normal config I guess they are bright. Odd choice for the original little monitor cabs but I guess they might be paired with some big bass cabs and need to fight their corner.
I assume they cross at 1000?

 

Hi, They cross @1.5k, 2nd LF, 1st order HF. Mainly intended to be distributed around a venue and/or on top of some subs.

 

Frank, I followed your advice and put 6Ohm resisters (I think) and I think I can live with them now. The bad news is that one of the bass drivers seems knackered. With deep bass there is quite pronounced buzzing/farting like noise. You need to turn the volume up very high to get to that stage though. I only did it to see if the sound hardened like before (it doesn't).

Anyway, I'll let Rob and Simon (Tenson) post their experience from yesterday's listening/measuring.