Greetings to all music lovers out there.
I'm ready to start my first DIY loudspeakers project, it will be a full range back loaded horn, a Fostex design enclosure that is published on their official website, the FE208EZ, that uses their FE208Esigma full range driver and the T900A horn super tweeter.
(I don't know if it's okay put the official Fostex links of the enclosure plan and drivers here, please let me know)
Anyway, in fact, It's not me that will build the enclosure, as I don't have the skills and the tools, I will pay for a woodworker that have some experience building loudspeakers, or a woodworker that never built loudspeakers, in any case, I think is important for me to know some general fundamentals about the construction to talk about with the builder.
Here's my doubts:
It's a must in loudspeakers design, the enclosure be inert, with no resonance at all, is that right? That's why the most recommended materials are MDF or Plywood? Because they have great internal vibration absorbent capabilities?
I noticed on the enclosure plan, that are two places that indicates the use of sound absorbents, what is this material?
If anyone knows some people that already builded this design, and it's using the loudspeaker with good results, I appreciate very much if you can indicate my thread for they contribute with valuable information, any information about more experienced people is very much appreciated.
I think for know it's just this, but I'm sure that will appears another doubts when I debate the subject with the woodworker...
Many thanks, best regards!
I'm ready to start my first DIY loudspeakers project, it will be a full range back loaded horn, a Fostex design enclosure that is published on their official website, the FE208EZ, that uses their FE208Esigma full range driver and the T900A horn super tweeter.
(I don't know if it's okay put the official Fostex links of the enclosure plan and drivers here, please let me know)
Anyway, in fact, It's not me that will build the enclosure, as I don't have the skills and the tools, I will pay for a woodworker that have some experience building loudspeakers, or a woodworker that never built loudspeakers, in any case, I think is important for me to know some general fundamentals about the construction to talk about with the builder.
Here's my doubts:
It's a must in loudspeakers design, the enclosure be inert, with no resonance at all, is that right? That's why the most recommended materials are MDF or Plywood? Because they have great internal vibration absorbent capabilities?
I noticed on the enclosure plan, that are two places that indicates the use of sound absorbents, what is this material?
If anyone knows some people that already builded this design, and it's using the loudspeaker with good results, I appreciate very much if you can indicate my thread for they contribute with valuable information, any information about more experienced people is very much appreciated.
I think for know it's just this, but I'm sure that will appears another doubts when I debate the subject with the woodworker...
Many thanks, best regards!
MDF is used because it is easy and inexpensive. But it is not the 'best' or even 'one of the best' choices from a performance point of view. Still - most speakers get built with it. It is is easy to get, easy to work with. Good plywood is a better material but the cost difference will be considerable on a horn design with lots of internal partitions to make.
The sound absorbent is anything dense and soft to try to reduce sound reflection off the surface. Most speaker materials suppliers will sell something suitable
The sound absorbent is anything dense and soft to try to reduce sound reflection off the surface. Most speaker materials suppliers will sell something suitable
Yes and no. It is a physical impossibility to erradiate panel resonance; all you can do is try to control it as best you can. MDF is technically mediocre for bass enclosures (fine for midrange & HF supports) but as noted it's cheap and widely available, so it gets used, and it's not catastrophic. Especially if heavily over-built, although most don't / can't go to those lengths. A quality void-free plywood tends to have superior MOE spec. (lighter & stiffer), and the laminated construction increases internal boundary losses.
Varies; usually 12mm - 15mm wool felt, jute, recycled denim, BAF wadding or similar. Avoid acoustic foam; it has its uses but for whatever reason, it just does not seem to suit these sorts of enclosures.
It's OK - decent. I don't mind it; it's better than some, but there are superior performing designs around also. Where it scores is relative ease of build; it has a lot of individual parts but no difficult angles &c. It's also of moderate size; horns get large quickly. All other things being equal (which is rare) larger horns tend to be less compromised than smaller, but it has a reasonable balance of extension / gain / linearity.
With such a specific set of drivers and enclosure design cited, have you actually heard this exact combination before?
This project would represent a not minor financial investment and it’d be a shame if the final results either didn’t float your boat, or was not compatible with your room. As Scott notes, the less compromised BLH can be large, and if made from MDF, this one will be a pain in the back to move.
This project would represent a not minor financial investment and it’d be a shame if the final results either didn’t float your boat, or was not compatible with your room. As Scott notes, the less compromised BLH can be large, and if made from MDF, this one will be a pain in the back to move.
Thank you very much for the clarifications.
Well, about other design possibilities: I understand that are a huge amount of other options, but I already 100% decided for this as my first project, and. to learn with.. the drivers are almost on the way
I have a friend that also have interest on this subject, I think he will shows up here with something sometime...
I was thinking about the amplification too, appreciate very much some clarifications about it:
I noticed that the match of set amps and back loaded horns is a classic match, what are the other factors besides the great sensitivity of the speakers and the low power of set amps, that contributes to this match work well together? is something about the sound character of the set amps working together with the back loaded horn signature sound? what about other technical factors beside the already mentioned sensitivity / power?
What about class a push pull tube amps and class a solid state amps with back loaded horns?
All information is very much appreciated, many thanks!
Well, about other design possibilities: I understand that are a huge amount of other options, but I already 100% decided for this as my first project, and. to learn with.. the drivers are almost on the way
I have a friend that also have interest on this subject, I think he will shows up here with something sometime...
I was thinking about the amplification too, appreciate very much some clarifications about it:
I noticed that the match of set amps and back loaded horns is a classic match, what are the other factors besides the great sensitivity of the speakers and the low power of set amps, that contributes to this match work well together? is something about the sound character of the set amps working together with the back loaded horn signature sound? what about other technical factors beside the already mentioned sensitivity / power?
What about class a push pull tube amps and class a solid state amps with back loaded horns?
All information is very much appreciated, many thanks!
Trying to understand if there's any benefit the external enclosure be made with sold wood...
Please, If you guys knows someone friends that builded and use this loaded back horn design and can put me in contact with they I appreciate very much!
Many thanks for all the insightful information till now
Please, If you guys knows someone friends that builded and use this loaded back horn design and can put me in contact with they I appreciate very much!
Many thanks for all the insightful information till now
Nothing to do with any kind of 'signature sound' although many believe it is; the technical reason is that a large proportion of the drivers used with back-horns are low-Q units designed to be paired with high output impedance (low damping) amplifiers, the majority of which are SET types.
What about them?
The class of amplifier operation taken purely in itself is broadly irrelevant in terms of electrical pairing; more important as noted is the output impedance. Most PP designs have a lower output impedance than single-ended types (this is not invariable, but broadly speaking is true). Solid-state -whatever it's designed to be. There are class A designs with a low output impedance, and class A designs with a high output impedance. You can always use resistive speaker wire or fixed series resistors to raise the output impedance of, say, a high power solid state amplifier and improve the electrical match to the speaker as desired.
It looks pretty. Otherwise, unless you are a very experienced cabinet maker with a thorough understanding that there can be no internal air-leaks for a folded horn, I would stay away. If you really, really must, ensure it is tight grained, as free from knots as possible, properly kiln dried and thoroughly sealed on all faces to reduce the chance of movement with changes in temperature and humidity. If you like the appearance, you could laminate some panels onto the faces, but unless you can ensure all of the above, I would not use them structurally.
As noted, I'm familiar with it in both design and sonic terms; a friend built a pair he used for a few years before he threw them out, and they're my default recommendation for these drivers (and the FE206En) to those who can't build something larger, and find the Dallas II too difficult. It has a reasonable extension / gain balance when used with the kind of amplifier / amplifier output Z anticipated (roughly in the 2ohm - 3ohm bracket). Upper corner frequency could be a little lower, but there are worse designs out there in this regard. It's one of Fostex's better factory design offerings.
Last edited:
Hello, appreciate very much your thoughts about this tube amplifier that was recommended for me by a japanese dealer, he asked what it will be my speakers, the drivers specifications, and music genres that I most like.
Here's the amp: ASTOR TO-EL34KG Push-pull Power amplifier | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO
Not too much info on the web about this amp, appears that Astor is dedicated to the japanese domestic market only, I still not talked with the dealer for he to explain this recommendation in details, will fo that this days, meanwhile, the thoughts of you guys here on the Forum is very much appreciated too, many thanks.
Here's the amp: ASTOR TO-EL34KG Push-pull Power amplifier | ホームオーディオ通販･下取･買取専門店エクスクルーシブ・オーディオEXCLUSIVE AUDIO
Not too much info on the web about this amp, appears that Astor is dedicated to the japanese domestic market only, I still not talked with the dealer for he to explain this recommendation in details, will fo that this days, meanwhile, the thoughts of you guys here on the Forum is very much appreciated too, many thanks.
In general, when dealing with tubes, you can't properly design a speaker without knowing its output impedance [damping factor/DF] unless it has variable DF tone controls and even then best to have these specs too.
This was standard practice way back when, but today they prefer to keep you ignorant to have a better chance of making a sale based on 'flooby dust' marketing spiel, looks, heft, etc., so personally don't even consider a brand/model without them.
That said, PP normally has a high DF, so output impedance is typically ~1/8 - 1/2 ohm, so doesn't raise the driver Qts too much: Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
GM
This was standard practice way back when, but today they prefer to keep you ignorant to have a better chance of making a sale based on 'flooby dust' marketing spiel, looks, heft, etc., so personally don't even consider a brand/model without them.
That said, PP normally has a high DF, so output impedance is typically ~1/8 - 1/2 ohm, so doesn't raise the driver Qts too much: Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
GM
Really? IME vintage BLH/SET amps [~matching impedance, i.e. current driven] sound rather 'syrupy' for lack of a better word. Very pleasing, with vocals, instrument harmonics to die for, but music wise has no real 'attack' ['tight']; 'limp wristed', one wag called it.
Of course as output impedance drops, driver Qts can increase, lowering the mass corner, so at ~0.383 Qts, DF has risen enough to no longer be a 'tail wagging the dog' scenario, so lose the 'signature' sound until one switches to SS with its rather 'dry'/'clinical' sound and why I normally add an 8-10 ohm non
inductive resistor in series to get a sort of 'best of both worlds' trade-off.
GM
I was referring to the 'back loaded horn signature sound' part, since the sonic character tends to vary from design to design.
Agreed about the reasons why SET / high output impedance amps & BLHs tend to get partnered off, especially since a lot of the drivers need all the help they can get from the amp or sufficient equivalent series R to become reasonably listenable rather than doing an impression of drill.
Agreed about the reasons why SET / high output impedance amps & BLHs tend to get partnered off, especially since a lot of the drivers need all the help they can get from the amp or sufficient equivalent series R to become reasonably listenable rather than doing an impression of drill.
That is the word i use (not something i personally like). It seems common particularily in 300B SETs, but that is down to execution and a better SET will not sound like that. I’ve only heard a few 300B SETs and they all did suffer. But other SETs did not (i am thinking of a particular 2A3 SET).
dave
It should be noted that with the FE208e∑ one really needs a tweeter above 5k, it is not really a FR.
The factory strongly recommends plywood for these.
With Chris’ help a friend built this horn for his FE206eSR. They are not great proportions and use a vast amount of plywood (4 sheets IIRC (chris?) even with plywood these were quite heavy). If you can manage the construction Dallas II is a better bet, and if you have the room, the Woden Vulcan uses the same Olson/Nagaoka style horn to extract the maximum possible out of this driver while still leaving room in your listening room.
dave
The factory strongly recommends plywood for these.
With Chris’ help a friend built this horn for his FE206eSR. They are not great proportions and use a vast amount of plywood (4 sheets IIRC (chris?) even with plywood these were quite heavy). If you can manage the construction Dallas II is a better bet, and if you have the room, the Woden Vulcan uses the same Olson/Nagaoka style horn to extract the maximum possible out of this driver while still leaving room in your listening room.
dave
Yes, 5k is often the primary impedance of the OPTs for many PP amps.
For this application SE is probably better, and given the efficiency, one does not need much power. A good 2A3 SET or an EL34/KT88/6550 single ended amp if the budget won’t stretch that far.
dave
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.