Richard Allen cg12l helppp

[Davidallen]

Can anyone tell me the ideal ported enclosure for a RA cg12L. Box and port size please hoping to cross at 1100hz. Thanks in advance.

 

[Galu]

Ah! Richard Allan!

I just had to add an image. 😎

 

[Galu]

It's interesting to note that the 8 ohm version of the CG12L was used in a Krix speaker system.

Sub Sonic's Content - Page 5 - StereoNET

The enclosure was sealed and had dimensions 670mm high, 490mm wide and 300mm deep.

 

[Galu]

I can't find any specifications for the CG12L.

I wonder how it differs from the more well known CG12?

However, the CG12 series drivers appear to share a common resonance frequency of 30Hz (see attached spec sheets).

 

[Lojzek]

One interesting drive unit. Thank you Galu for the beautiful photos.

 

[Galu]

The "Charisma" bass reflex enclosure designed for the GC12C version had dimensions 686mm x 392mm x 305mm (h x w xd) including a 38mm plinth, and volume 78.5 litres.

The enclosure tuned frequency was 70Hz.

This may be a good guide for your build.

 

[Galu]

Note, however, that the GC 12C version has a treated cone, giving it a higher moving mass for use in "smaller" bass reflex enclosures (and a slightly lower resonance frequency).

So, as I said, just a guide! 😎

P.S. I obtained the RA information from the UK Hi-Fi History Society - a truly fantastic archive: UK Hi-Fi History Society - Richard Allan Loudspeakers

 

[Galu]

Box and port size please

From the above discussion, you may now realise that those figures are not so simple to obtain. However, there follows a quick and easy (if not optimum) suggestion.

Back in the 1970s, the compact enclosure was made in its thousands to suit 12" speakers like yours, with resonance below 35Hz.

The internal volume of the compact enclosure is 2 cu ft, and it may be tuned in one of two ways:

• A narrow vent 12" x 3/4" (in a 3/4" thick baffle board).
• A cardboard or plastic tube of internal diameter 2" and length 6".

The information is courtesy of Gilbert Briggs of Wharfedale fame - I'll let you do the metric conversions! 🙂

Any questions, please ask.

 

[Davidallen]

Hi Galu, many thanks for your input it is much appreciated. I have the opportunity to purchase two of these. If the surrounds are shot could I replace them with the newer foam ones.
Cheers

 

[Davidallen]

I forgot to mention, these have been doped on the rear side.

 

[Galu]

If the surrounds are shot could I replace them with the newer foam ones.

A special feature of these drivers is their cambric surrounds.

Foam surrounds are highly likely to alter the performance of these particular drivers in a negative way.

If the surrounds are shot, I would look elsewhere.

 

[Davidallen]

Thanks I do have the opportunity to visually check them. Cheers