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given a fixed enclosure size (narrow baffle, floor-stander) I could see that both a proven Pensil design and a BVR (such as Scott's Derwent) would be viable options.
Is there a reason to choose one over the other ?
p.s. The FH3 is an option but not sure the 'customer' will approve this design as yet.
Is there a reason to choose one over the other ?
p.s. The FH3 is an option but not sure the 'customer' will approve this design as yet.
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They will sit either side of a TV. Not intended to be an HT system, but a step up from what the TV regularly provides. Amplifier is a LINN - a stereo that isn't being used since the original speakers were flood damaged.
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do I take it then, that this is a subtle difference and that bass, for example, will be perceived more or less as the same from both options if properly designed (around the same driver with the same external cabinet dimensions) ?
Quite possibly not a subtle difference at all - and even with appropriate adjustments, which depending on the drivers could be simple or extensive, the LF extension and articulation would be the areas quite likely not to be more or less the same
It's not clear that the question of "which driver?" has yet been answered, but if 'customer/ WAF' is at all part of the calculus, based on personal experience with my own "customer", I'd bet on the A7.3 /Pensil - even without "helper" woofers, as Jeff says, it'd be a huge step up from any built-in TV speaker I've yet heard.
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Well, if you think the difference may not be subtle I'd value your opinion as to how they might differ in their subjective sound quality in the bass department. I've had this pet theory that for a given box size, bass performance is pretty much the same for different driver loading methods but as I'm quite possibly wrong I'd like to hear from others with more experience.
The driver question - well I am in favour of using EL-70's. I have a pair at home in an Onken style box and like the sound. I like their appearance too. The use of an A7 isn't being considered as I don't see enough benefit from the higher cost. I'd consider using the CHR-70 but prefer paper, unfortunately the CHP-70 doesn't appear to have a suitable frequency response. I share the frustration of others that MA have not continued the qualities of the EL-70 into a current production model and frankly I find it strange that this still isn't on his 'roadmap'.
I don't think it's a good idea to consider the current TV as the standard to beat, I'd rather be aiming quite a bit higher. I have full confidence in the mid range and above for any of these 70mm drivers - it's the bass I worry about and it's very dependent on the box.
WAF is not strictly relevant - the 'customer' is my sister in the UK. It's a stone cottage with flagstone flooring and the ceiling is not that high. There are rugs and chairs but I expect the room to be fairly lively. It is very desirable to make the speaker small, especially the baffle width. If I choose the Pensil I will narrow it a little. I may float the idea of the FH3 - but my worry with this one is that it is sensitive to positioning (as well as having an unconventional appearance).
The driver question - well I am in favour of using EL-70's. I have a pair at home in an Onken style box and like the sound. I like their appearance too. The use of an A7 isn't being considered as I don't see enough benefit from the higher cost. I'd consider using the CHR-70 but prefer paper, unfortunately the CHP-70 doesn't appear to have a suitable frequency response. I share the frustration of others that MA have not continued the qualities of the EL-70 into a current production model and frankly I find it strange that this still isn't on his 'roadmap'.
I don't think it's a good idea to consider the current TV as the standard to beat, I'd rather be aiming quite a bit higher. I have full confidence in the mid range and above for any of these 70mm drivers - it's the bass I worry about and it's very dependent on the box.
WAF is not strictly relevant - the 'customer' is my sister in the UK. It's a stone cottage with flagstone flooring and the ceiling is not that high. There are rugs and chairs but I expect the room to be fairly lively. It is very desirable to make the speaker small, especially the baffle width. If I choose the Pensil I will narrow it a little. I may float the idea of the FH3 - but my worry with this one is that it is sensitive to positioning (as well as having an unconventional appearance).
Good choice on the driver - works well in every enclosure I've heard yet
Even (or especially) at age 60, I'd never try to second guess my wife, or two sisters as to aesthetics - send her some pictures of the FH3 and Pensils.
Be careful trying to reduce width of enclosures - as an MLTL, the Pensil wouldn't likely be much of a problem as long as net CSA, line length and port dimensions were retained, but the FH3 is a different story. However a major consideration with any of Mark's drivers is remembering the width of mounting flange, and to allow for relieving the rear side of mounting through hole.
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Scaling cabinets is always problematic, unless you know exactly what you're doing, and even then, it's rarely ideal. As far as the pensils are concerned, being an MLTL (albeit a specific alignment), providing you maintain the pipe and vent CSAs, they will work reasonably. Forget trying to do that with FH3 though; it won't work.
I don't like trying to give subjective descriptions on sound, since they invariably mean different things to different people. The power response of a horn loaded reflex & MLTL are different within their operating BW; the former couples to more air. Whether that's a good or bad thing or not is a matter of opinion. Ditto the quasi-MTM radiation pattern of the double (over-under) terminus types. YMMV.
I don't like trying to give subjective descriptions on sound, since they invariably mean different things to different people. The power response of a horn loaded reflex & MLTL are different within their operating BW; the former couples to more air. Whether that's a good or bad thing or not is a matter of opinion. Ditto the quasi-MTM radiation pattern of the double (over-under) terminus types. YMMV.
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OK, so as the FH3 is not scaleable in the manner I've mentioned I'll leave that off the table for now.
If I remember what I read on MLTLs they do a good job of loading the driver, when stuffed appropriately the multiple resonances conspire to provide a broad range of frequencies over which the driver is adequately loaded - unlike a simple BR box which is tuned to one resonant frequency.
For the horn-loaded reflex I'm not so sure I understand how it works as there's little published literature that I've seen. I'm wondering if the horn loading provides a similar benefit in widening the resonance of the reflex, providing a broader range of driver loading without the ripple that has to be damped on an MLTL ?
If I remember what I read on MLTLs they do a good job of loading the driver, when stuffed appropriately the multiple resonances conspire to provide a broad range of frequencies over which the driver is adequately loaded - unlike a simple BR box which is tuned to one resonant frequency.
For the horn-loaded reflex I'm not so sure I understand how it works as there's little published literature that I've seen. I'm wondering if the horn loading provides a similar benefit in widening the resonance of the reflex, providing a broader range of driver loading without the ripple that has to be damped on an MLTL ?
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Well, despite the insight, there are no firm votes for why a BVR or MLTL might be the better choice - not like this forum to be devoid of strong opinions 
Come to think of it, I haven't seen 'curves' for the two options I'm considering.
Without better information, I'm leaning towards the BVR - the build is, for me, no more complex than the MLTL and it requires no stuffing, and it 'couples to more air'. Oh, and I love the Lake District, spent many hours scaling those peaks.
The BVR also looks scaleable (i.e. shave an inch off the width) - in this case I assume one wants to maintain the same volume for the reflex cavity, the low-pass filter / throat should be kept with same narrow dimensions (it's 'onken port' like aspect ratio may perhaps offer some broadening of the reflex loading ?) and the horn opening doesn't look super critical ?
The micro-tower looks interesting, the use of two drivers offers some clear benefits here.
Come to think of it, I haven't seen 'curves' for the two options I'm considering.
Without better information, I'm leaning towards the BVR - the build is, for me, no more complex than the MLTL and it requires no stuffing, and it 'couples to more air'. Oh, and I love the Lake District, spent many hours scaling those peaks.
The BVR also looks scaleable (i.e. shave an inch off the width) - in this case I assume one wants to maintain the same volume for the reflex cavity, the low-pass filter / throat should be kept with same narrow dimensions (it's 'onken port' like aspect ratio may perhaps offer some broadening of the reflex loading ?) and the horn opening doesn't look super critical ?
The micro-tower looks interesting, the use of two drivers offers some clear benefits here.
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What did the designer say about scalability just 4 posts ago?
Definitely - I personally find top mounting the second driver to have advantages over the "true" bipole, but the same comment applies to "re-engineering" it, should the inclination arise.
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that's a bit condescending don't you think ? Anyhow, from my perspective, Scott commented on the difficulty of scaling, he didn't provide any specific advice on scaling of a BVR design. He did comment on the scaleability of an MLTL and the FH3.
I'm wondering if the BVR is an under-represented technique, I don't see many people exploring this approach other than Scott. It looks very interesting and I'd like to learn a bit more.
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Interesting question. Onken, BVR, DCR, DCAAV and Karlson/Fulmer type loadings are talked about from time to time. Their adherents sometimes do not really explain their design methodologies very clearly.
I think this leads to a sense that there is something mysterious, some arcane piece of information, that might explain the 'magic' associated with each approach. Everybody knows (right?) how to design a Sealed or BR enclosure and free modelling tools are all over the place. How do you go about designing a BVR exactly? What can you model it in? How do you know if you are doing it right?
Despite the efforts of many here, the world at large is a bit wary of things they don't think they understand. Few can afford to do lots of empirical research and build lots of boxes, and those who do are not always willing to give ALL of their hard fought knowledge for free.
Interesting question.
the blakk one
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