Some page by page comments (most have already been seem on these pages by me or others) and some extensions & support for what is written.
I am very attracted to the concept & execution of this design. They look fantastic.
Page 6:
Attached areimpedance plots of the same FE166e with and without a dustcap. Also note that the rise at high frequencies is about half what Morgan illustrates (meaning that you may need to play with the zobel).
Note: i have measures of some 20 other FE166 so i can check consistency.
Page 8:
Note that the analysis of edge diffraction ripple is only valid for on-axis listening, and the further off-axis you are the more the end result will move away.
Page 9:
A more generalized treatment of Passive Line Level Baffle Step Compensation by Paul Joppa (now at Bottlehead).
Page 10: Attached is a key diagram from Tappan's paper.
dave
I am very attracted to the concept & execution of this design. They look fantastic.
Page 6:
Attached areimpedance plots of the same FE166e with and without a dustcap. Also note that the rise at high frequencies is about half what Morgan illustrates (meaning that you may need to play with the zobel).
Note: i have measures of some 20 other FE166 so i can check consistency.
Page 8:
Note that the analysis of edge diffraction ripple is only valid for on-axis listening, and the further off-axis you are the more the end result will move away.
Page 9:
A more generalized treatment of Passive Line Level Baffle Step Compensation by Paul Joppa (now at Bottlehead).
Page 10: Attached is a key diagram from Tappan's paper.
dave
Attachments
Continued, these are points i have been hammering away at for years.
Page 13: The brace is placed dead-centre. This is the worst possible place for it. Moving it over by a panel width even can make a differemce.
As anyone who follows my designs i like to brace the driver to the rest of the box, for this one i'd likely use 2 verticle brace, one right behind the driver.
Page 14: I strongly believe that MDF is not a suitable material for building loudspeakers out of. Use 18mm Baltic Birch (or similar) and you will end up with a better speaker with greater downward dynamic range.
dave
Page 13: The brace is placed dead-centre. This is the worst possible place for it. Moving it over by a panel width even can make a differemce.
As anyone who follows my designs i like to brace the driver to the rest of the box, for this one i'd likely use 2 verticle brace, one right behind the driver.
Page 14: I strongly believe that MDF is not a suitable material for building loudspeakers out of. Use 18mm Baltic Birch (or similar) and you will end up with a better speaker with greater downward dynamic range.
dave
Attachments
I fear the minor queries raised thus far could seem depressingly negative 
-they're not meant that way of course, so I'll quickly get in at this point that irrespective of these, I still think it's a neat little box & should give decent results for anyone wanting something along these lines. 
-they're not meant that way of course, so I'll quickly get in at this point that irrespective of these, I still think it's a neat little box & should give decent results for anyone wanting something along these lines.
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Page 15: Because it is so hard to compare 2 separate graphs i have created an overlay of Figure 19 (black) and figure 23 (blue) for easier comparison.
Morgan, how thick is the felt, and is it wool, corrom, or polyester felt?
As Toole has shown, on-axis FR is not a great indicator of sonic performance. It would be nice to see a set of 10 degree vertical & horizonatal plots (but i'll take the listening results as fine)
dave
Morgan, how thick is the felt, and is it wool, corrom, or polyester felt?
As Toole has shown, on-axis FR is not a great indicator of sonic performance. It would be nice to see a set of 10 degree vertical & horizonatal plots (but i'll take the listening results as fine)
dave
Attachments
A very good article, and nice to see Morgan do a sealed box that only goes to 85 Hz, This meshes well with Toole & Geddes suggesting that this kind of performance mated with multiple mono woofers for a full-range system.
This is also somewhat similar in concept (with added woofers) of the new Bottlehead system. Morgan's speaker has had a lot more thought put into it.
The basic configuration is also broadly similar to a quick-n-nasty break-in box we made for FE167 (quick-n-nasty hence the standard BR port) and the Classic GR Fonken so you can see why i am attracted to this design. Note that the GR when finally done had a bevel on the vertical edges.
In the spirit of articles being a stimulus for putting new twists on things -- Every designer has, at least, a slightly different take on things: these are things that i would at least consider changing.
I would build this from plywood, enhance the bracing, and use one of my fully treated FE166eN (or at least add phase plugs).
As well, from experiments we have conducted with FE126 + series R vrs FE127, i would consider executing something similar with FE167 so as to reduce the series R. And based on the very good results we have had with the high resistance ports in terms of getting away from the things i don't like about both sealed & ported enclosures, i'd would probably turn into a Classic GR Fonken167 allowing us to eliminate the series R completely (& possibly some of the BSC)
Very good article Morgan. Kudos.
dave
This is also somewhat similar in concept (with added woofers) of the new Bottlehead system. Morgan's speaker has had a lot more thought put into it.
The basic configuration is also broadly similar to a quick-n-nasty break-in box we made for FE167 (quick-n-nasty hence the standard BR port) and the Classic GR Fonken so you can see why i am attracted to this design. Note that the GR when finally done had a bevel on the vertical edges.
In the spirit of articles being a stimulus for putting new twists on things -- Every designer has, at least, a slightly different take on things: these are things that i would at least consider changing.
I would build this from plywood, enhance the bracing, and use one of my fully treated FE166eN (or at least add phase plugs).
As well, from experiments we have conducted with FE126 + series R vrs FE127, i would consider executing something similar with FE167 so as to reduce the series R. And based on the very good results we have had with the high resistance ports in terms of getting away from the things i don't like about both sealed & ported enclosures, i'd would probably turn into a Classic GR Fonken167 allowing us to eliminate the series R completely (& possibly some of the BSC)
Very good article Morgan. Kudos.
dave
Attachments
I fear the minor queries raised thus far could seem depressingly negative
Agreed. Think of the comments as polish on an excellent basic design.
dave
They sounded very nice with the Scrapbox Challenge, even better with one of DHTRob's amps. The unfortunate part was that TheEyeLady saw them and immediately demanded that I make my speakers that small, nicely designed (visually), and unobtrusive. I tried to explain the realities of dynamic range and frequency response, but these fell on, errr, deaf ears.
If you subscribe to Toole & Geddes the mains need not be large... and the size of the woofers can be distributed thruout the room. If you sawed off the top of your NHT clones and optimally placed the woofers, yours would be even less intrusive
Unless of course if you have gotten the Acoustats back in action. No way to shrink those.
dave
Unless of course if you have gotten the Acoustats back in action. No way to shrink those.
dave
The ESLs-Formerly-Known-As-Acoustats (by the time I was done, the only remaining Acoustat parts were the stators) are banned from the house until I can get house with a room where they can't be seen by visitors.
Unfortunately, the woofers in the NHTs are optimally placed wrt the top, but I only run those down to 40 Hz or so. TEL objects not only to the big satellites, but the pair of 10 cu ft subs, well... deep bass and effortless SPLs ain't her thing. I have been instructed to build a pair of Arpeggios or the equivalent, but have managed to stave that off so far.
Unfortunately, the woofers in the NHTs are optimally placed wrt the top, but I only run those down to 40 Hz or so. TEL objects not only to the big satellites, but the pair of 10 cu ft subs, well... deep bass and effortless SPLs ain't her thing. I have been instructed to build a pair of Arpeggios or the equivalent, but have managed to stave that off so far.
Well, that's a pretty personal judgment. For me (as a dynamics and frequency range enthusiast), "not bad" is the best case for something that small and inexpensive. Let me put it this way: they sounded as good as any single driver system in the under-$2000 range that I've heard.
That was the impression I got from Morgan in his article. As far as personal judgement, I've already wasted too much time and money on Fostex single driver speakers. There are lots of "not bad" FE166 designs out there - I'm a little disappointed that someone of Jones' expertise (and he DOES possess a lot of that) didn't come up with something more interesting.
John
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I find it interesting in that he choose to do a project that is so different for said driver.
I would have instantly dismissed FE166 stand-alone in a sealed cabinet. That he is getting results he is happpy with is eye opening.
I don't agree with all his design choices, but he has presented something different and therefore has expanded our horizons.
John, have you ever tried properly tarting up your Fostex to eliminate most of the rough edges that challenge your sensibilities? Which Fostex have you experienced?
If not clear, i could not live with any stock Fostex (that i have heard) except maybe FE108eS.
dave
I would have instantly dismissed FE166 stand-alone in a sealed cabinet. That he is getting results he is happpy with is eye opening.
I don't agree with all his design choices, but he has presented something different and therefore has expanded our horizons.
John, have you ever tried properly tarting up your Fostex to eliminate most of the rough edges that challenge your sensibilities? Which Fostex have you experienced?
If not clear, i could not live with any stock Fostex (that i have heard) except maybe FE108eS.
dave
That would be interesting, but in fairness, he can't appeal to everyone / do everything. What has been presented (even if some of us have some quibbles with certain points) is a nice, well documented & simple to build project that would be a good starting point for people new to DIY speaker building. It's not particularly aimed at those who wouldn't bat an eyelid at something more exotic.
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