A7 Thirlmere or Coniston^2

[buzzforb]

There were some CSS EL70 for sale in the swap meet and I went looking for possible plans or ideas. I found the the above plans and was interested in the possiblities. That being said, I have read on many occasions that the A7 in theory should best the EL70 in sound quality. What are the opinions of the possiblity of the A7 in one of these type enclosures? More info: I love the detal of the A7's, but would like more ouput/dynamics/spl and more bass. I know that a FAST is an option, but was wondering what could be had from the above type system.

[Scottmoose]

They were designed for the EL70. Other drive units will require a box designed for them.

[buzzforb]

I understand. If the idea had merit, I was going to speak with you about the posisblity of commisioning a design for the A7's. Does the design of either of these cabinets provide the possiblity of gains in the areas I mentioned and what are some limitations and considerations?

[planet10]

Scott might well slap me about the head & shoulders for this suggestion, but if you had to do a flyer on a cabinet for the A7 that was not designed for the A7, i would suggest that Lotus^2 is a better bet.

It would be a fairly big flyer -- about 50".

Personally i would spend my money on helper woofers.

dave

[chrisb]

Originally Posted by buzzforb

There were some CSS EL70 for sale in the swap meet and I went looking for possible plans or ideas. I found the the above plans and was interested in the possiblities. That being said, I have read on many occasions that the A7 in theory should best the EL70 in sound quality. What are the opinions of the possiblity of the A7 in one of these type enclosures? More info: I love the detal of the A7's, but would like more ouput/dynamics/spl and more bass. I know that a FAST is an option, but was wondering what could be had from the above type system.

Scott and Dave might both wanna slap me a bit as well, but having a fair bit of experience building and listening to a variety of enclosures for both named drivers over the past several years, here goes:


I own both drivers, and would be quite happy with either of them - actually if I had to make a Sophie's choice between the two right now, it'd probably be for the EL70. Let's hope that once current stock is depleted that some future model of Mark Audio branded paper cone driver equals or surpasses the EL70's performance. I've no doubt Mark could achieve that- market demand would be the impetus to drive production.

Back to the question: there are two simple methods that could probably deliver the "more" you're looking for, with which I think you're already familiar from these fora: dual drivers per enclosure, a la the Castle Microtower, or any of several other twin systems, and some kinda FAST. When relieved of the heavy lifting, either of these drivers can work quite well in a variety of small enclosures, from simple to more complex construction details, Even when combined with helper woofers, the total size could be less than the Coniston, Lotus, etc.

However, if you're still inclined to a larger / double mouth enclosure designed for the Alpair 7 that will also work with the EL70, and want to try without woofers, two words - Woden Maeshowe. Aside from the curved side panel, this is no more complicated a build than the Coniston or Lotus, and certainly squeezes the best balance of dynamics, low end extension and articulation that I've yet to hear from an unassisted single of either of these drivers. They definitely surpass the Pensil, but lack the latter's compact form factor, simplicity of build and room placement flexibility.

TANSTAFL

Originally Posted by planet10

Scott might well slap me about the head & shoulders for this suggestion, but if you had to do a flyer on a cabinet for the A7 that was not designed for the A7, i would suggest that Lotus^2 is a better bet.

It would be a fairly big flyer -- about 50".

Personally i would spend my money on helper woofers.

dave

build complexity aside, I think the primary question to be considered is - which design is most suitable to the room

IINM, when Dave says "helper woofers", he's referring to what we've played with in our own FAST systems - stereo bass, XO'd in the upper 200-low300 range; active or passive your choice

[buzzforb]

Originally Posted by chrisb

I own both drivers, and would be quite happy with either of them - actually if I had to make a Sophie's choice between the two right now, it'd probably be for the EL70.

Could you explain your reasons.

Originally Posted by chrisb

TANSTAFL

Nope

Originally Posted by chrisb

build complexity aside, I think the primary question to be considered is - which design is most suitable to the room

I think this is part of my problem. I have a medium room, being 16' x 16', but it is open on one side.

Originally Posted by chrisb

IINM, when Dave says "helper woofers", he's referring to what we've played with in our own FAST systems - stereo bass, XO'd in the upper 200-low300 range; active or passive your choice

I agree completely with you and Dave on the helper woofer, but it would be yet another thing to learn and my wife is starting to growl at me when I talk about audio. I have some Seas CA22RNX, but have not even looked at them other than a glance. I had considered building something like TonyGee's Classic and just stacking the a7 on top with a crossover, but once again, I dont even know if this is a stupid idea. Oh well, more reading.

[chrisb]

Originally Posted by chrisb
I own both drivers, and would be quite happy with either of them - actually if I had to make a Sophie's choice between the two right now, it'd probably be for the EL70.

Originally Posted by buzzforb

Could you explain your reasons.

simply put, I prefer the EL70's extended LF response, overall tonality and more warmly textured upper midrange

Originally Posted by chrisb
build complexity aside, I think the primary question to be considered is - which design is most suitable to the room

I think this is part of my problem. I have a medium room, being 16' x 16', but it is open on one side.

anyway you could sketch a rough floor plan that also references windows, access doorways, closets, furniture etc? absent that information no doubt plenty of suggestions could be made that might not suit the actual livability of the system in-room

Originally Posted by chrisb
IINM, when Dave says "helper woofers", he's referring to what we've played with in our own FAST systems - stereo bass, XO'd in the upper 200-low300 range; active or passive your choice

I agree completely with you and Dave on the helper woofer, but it would be yet another thing to learn and my wife is starting to growl at me when I talk about audio. I have some Seas CA22RNX, but have not even looked at them other than a glance. I had considered building something like TonyGee's Classic and just stacking the a7 on top with a crossover, but once again, I dont even know if this is a stupid idea. Oh well, more reading.

A fine enough driver - no doubt Tony's Classic is one of many designs in this approx size/form factor in which it could work well enough to support the A7. Not at all an unwise idea to use existing drivers - appropriately.

[buzzforb]

Here is the room and a proposed FAST. For me, the difficullt thing about the B&W teardrop, is the interior cavity. What if the interior wwas kept in cube form and treated as a normal box speaker. THe main benefit of the teardrop is the baffle diffraction, correct. So if i can achieve that gain and properly addres issues with cubic interior, I have a B&W on the cheap. I would make the teardop out of quarters that could be easily shaped, finsihing the interior and cutting the face, before temporarily connecting together(pocket screws or dows) and then turned to meet the outer shape needed. As i understand it, the teardrop is excellent for diffraction, but creates problems whenusing round interior for standing waves. couldnt these be dealt with in the above proposed idea with either professional absorptionmaterial or custom made spikes like you see in anechoic chambers.

[buzzforb]

I can get a 12" SLS right now for the same price as 10" pictured in the drawing. Pros and cons? I could always double up the 10", but seems unnecessary. Then again, I am a rookie. BTW. Te box could easily be squared off. Just playing with good looking ideas. Waves coming off driver will be below rolloff i believe, so diffraction should be a big issue, I thkn.

[chrisb]

Originally Posted by buzzforb

Here is the room and a proposed FAST. For me, the difficullt thing about the B&W teardrop, is the interior cavity. What if the interior wwas kept in cube form and treated as a normal box speaker. THe main benefit of the teardrop is the baffle diffraction, correct. So if i can achieve that gain and properly addres issues with cubic interior, I have a B&W on the cheap. I would make the teardop out of quarters that could be easily shaped, finsihing the interior and cutting the face, before temporarily connecting together(pocket screws or dows) and then turned to meet the outer shape needed. As i understand it, the teardrop is excellent for diffraction, but creates problems whenusing round interior for standing waves. couldnt these be dealt with in the above proposed idea with either professional absorptionmaterial or custom made spikes like you see in anechoic chambers.

More going on inside that teardrop than meets the eye;

per "Technologies" at B&W website

Cavities, of course, have their own internal resonance problems. Indeed, it is to get away from these that we use tubes in the first place. However, for once physics is on our side. Extensive computer modelling and practical experimentation showed that, if the cavity is a sphere whose diameter had a particular ratio to the diameter of the driver diaphragm, and a hole directly opposite the driver which is the same diameter as its diaphragm and leads to a tapered tube, the internal resonances are to a large extent eliminated. Any residual effects are readily mopped up by wadding inside the sphere and tube. The sphere also has the ideal shape for avoiding diffraction effects on the outside of the enclosure, with consequent benefits to the imaging.

interesting video:

Bowers & Wilkins - Sphere Tube

I think it's fair to say this is a very thorough piece of acoustic and production engineering - unfortunately, price aside, there are performance aspects of the large N series that frankly leave me a bit cold.


Back to your plan - you might well end up with almost perfect cube for a primary volume, in which initial reflections could be more problematic than could easily be controlled with materials that would fit inside the enclosure. A steeply tapered aperiodic or transmission line enclosure that could still be contained within your teardrop exterior might be worth considering.

I hadn't clued in before to your intention to attempt this shape - out of curiosity what materials and construction methods were you planning on using?