• Disclaimer: This Vendor's Forum is a paid-for commercial area. Unlike the rest of diyAudio, the Vendor has complete control of what may or may not be posted in this forum. If you wish to discuss technical matters outside the bounds of what is permitted by the Vendor, please use the non-commercial areas of diyAudio to do so.

El70 in Pensil?

I'm not doing a Pencil for the EL, but of the existing enclosures, the CHP cabinet will be the most flexible.

Ok, thanks Scott. May I ask why not one specifically for the EL70 since they are sister products to the MA drivers?

Also, how would it change the sound if the driver was placed closer to the top of the cabinet? Is there a reason that the driver is placed lower?
 
Ok, May I ask why not one specifically for the EL70 since they are sister products to the MA drivers?

Also, how would it change the sound if the driver was placed closer to the top of the cabinet? Is there a reason that the driver is placed lower?

If you 'run the numbers' for a T/S max flat vented alignment of these two drivers, you'll see that the EL70 wants to 'feel' a stiffer air mass 'spring' supporting it (smaller cab tuned higher), so while you could put it in the Pensil, it will need more damping in the form of stuffing, but due to the nature of things this will not only yield a different roll off slope, but acoustically mass load the driver enough to alter its mids/lower treble response to one of a perceived 'dullness'.

This is the problem I had when loading them into an existing MLTL of similar dimensions as the Pensil except with a 2" ducted vent that over-damped them somewhat, consequently overemphasizing the driver's inherent sibilance up in its break-up modes BW, something I can't tolerate in any speaker since it painfully changes the pitch of my tinitus.

By the same token, others hearing and/or playback system may be such that this is beneficial, so as always when someone wants to use a driver other than the one a speaker was designed for it boils down to whether they are willing to gamble some time/materials building at least one prototype to see if it can be made to work or a complete new design is required.

High aspect ratio vented cabs once long enough will have closed pipe 1/4WL resonance modes that affect driver loading, so if the driver is at the closed end it will get the maximum loading, ergo the widest resonant BW. Usually a good choice for a (sub)woofer app where its resonant HF BW will be rolled off with an XO, but not so much for a wide BW one since it means more BW to damp.

Moving the driver down the pipe then equates to less damping required if the right spot is found. This point varies based on the pipe's dimensions, so refer to MJK's Classic TL Alignment Tables doc for close enough calculated solutions.

GM
 
My goal was to try to salvage the Pencil cabinets that I started for the CHR-70. I was not crazy about this driver even after the recommended 100+ hours so I sold them. Was hoping to try the EL in these boxes but now I'm not sure.

Either way, I just finished the cabinets and for now I cut the holes smaller and put in my trusty pair of 871s and they sound pretty damn good - better in fact than in the Needles.
 
......how severely that'll mass load the diaphram though I'm not sure.

Well, just looking at acoustic impedance sims, the EL-70 MLTL has the lowest damping overall, just too much for my ears and another older gent with a worse case of tinitus who could hardly tolerate them above Muzak levels, with the EL-70 Pensil highest and the CHR-70 Pensil in between, very close to the EL-70 MLTL. Again, all very subjective on my part WRT my reference.

GM
 
Here they are (not perfect & unfinished):
 

Attachments

  • Pensil 045.jpg
    Pensil 045.jpg
    498.1 KB · Views: 165
  • Pensil 047.jpg
    Pensil 047.jpg
    415.3 KB · Views: 151
  • Pensil 048.jpg
    Pensil 048.jpg
    493.3 KB · Views: 148