Fair enough re bi-amping -
Re TL terminus, performance wise, there's probably not much effective audible difference at the listening position between front or rear location, but for the type of short tapered TLs that Dave has designed in the several enclosures (at least 4 that I can immediately remember) , the rear exit makes for a much simpler build - no folds, tapered side walls, and progressively stuffed to achieve near aperiodic loading, as can be seen in the impedance sweep of first build - Tysen.
Re TL terminus, performance wise, there's probably not much effective audible difference at the listening position between front or rear location, but for the type of short tapered TLs that Dave has designed in the several enclosures (at least 4 that I can immediately remember) , the rear exit makes for a much simpler build - no folds, tapered side walls, and progressively stuffed to achieve near aperiodic loading, as can be seen in the impedance sweep of first build - Tysen.
Does it make a noticeable difference if the "midrange" enclosure is a TL or simple sealed design, as long as it's properly aperiodically damped along with some means of diverting the reflected back waves away from the driver?
Kind of like this?
I do like the idea of the TL since it can almost completely get rid of the back wave as Dave said earlier.
Also, does the overall size of the enclosure matter in this application?
I would imagine larger might be better to get the box resonance down below the operating range of the driver, to become somewhat a non-issue.
Kind of like this?
I do like the idea of the TL since it can almost completely get rid of the back wave as Dave said earlier.
Also, does the overall size of the enclosure matter in this application?
I would imagine larger might be better to get the box resonance down below the operating range of the driver, to become somewhat a non-issue.
Well, I'll chime in to start with a clarification of my understanding of the term "aperiodic" as it relates to loudspeaker enclosures - to start with, they're not sealed as the opening line our earlier post seems to suggest, but rather strategically leaky. An aperiodic enclosure doesn't necessarily mean a "TL"
With appropriate shaping, damping of side walls, and progressive damping of the internal volume, you should be able to mitigate reflections back to the driver.
What exactly is it that you want to read about "the TL" - or more precisely, what would be its objective in this project.? There's tons written & on the web on the general subject, but wading through that data to find what would be applicable to any given situation can be rather onerous.
Out of curiosity, what project was that photo from? I can't recall seeing it before
With appropriate shaping, damping of side walls, and progressive damping of the internal volume, you should be able to mitigate reflections back to the driver.
What exactly is it that you want to read about "the TL" - or more precisely, what would be its objective in this project.? There's tons written & on the web on the general subject, but wading through that data to find what would be applicable to any given situation can be rather onerous.
Out of curiosity, what project was that photo from? I can't recall seeing it before
Kind of like this?
If those slots in the back are openings then this is an elaborate execution of a midTL.
dave
Yes, I know what the differences are between sealed, ported, TL and aperiodic.
On the other hand, I don't know the exact science as far as progressively damping the enclosure, or even if there is an exact science to it. Just trial and error? Tune by ear? Or damping the enclosure walls and using those aperiodic "pucks" as I call them?
Actually, I think I would rather use the "pucks" as it would make it easier to replicate exact tuning several times over. I wouldn't want to get damping densities different between several enclosures, thus skewing results between them.
The reason for wanting to learn more about the midTL design is because of what Dave said earlier about that design pretty much totally eliminating the back wave of the driver. I'm assuming that almost total elimination of the back wave would make the entire upper mid-bass, midrange and treble that much clearer, but also possibly give it that magical open baffle sound, or at least something close to it. Not referring to the openness from the delayed back wave response, but just the clean, natural, effortless, open sound.
My little Fostex FE103e's pretty much do that now, and they are in a simple but large (large for them anyway) 0.43 cf highly damped sealed enclosure with perfectly parallel walls.
My point being, the midrange is the most important part of a quality speaker system, and this time around, I want to get it absolutely right. I want pretty much everything from the crossover point on up to 20 kHz to be as near perfect as possible using the Alpair 10.2, and later the 10.3, which I already know will require a different sized enclosure.
The two pics that I provided are not mine. I did a Google search and found them.
Yes, those are two slots on the rear of the enclosure.
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I have a feeling that those won't work all that well for this appliction.
That is the theory...
dave
Okay. Solves that problem.
Quick question about my current speakers with the Vifa/Fostex combo...
I just switched out the Fostex drivers for the Alpair drivers, and I reinstalled the 10 ohm/10 watt resistors. Only reason being I didn't want to drastically throw off the crossover in some way. I don't think it would as it wasn't there originally.
I think I'll just leave it there for the rest of the day and pull it out tomorrow if things don't start sounding better.
This is the first time these Alpairs have been played in over 3 years, so it's expected to not sound that great right away. I've only had them playing for about a half hour so far.
Quick question about my current speakers with the Vifa/Fostex combo...
I just switched out the Fostex drivers for the Alpair drivers, and I reinstalled the 10 ohm/10 watt resistors. Only reason being I didn't want to drastically throw off the crossover in some way. I don't think it would as it wasn't there originally.
I think I'll just leave it there for the rest of the day and pull it out tomorrow if things don't start sounding better.
This is the first time these Alpairs have been played in over 3 years, so it's expected to not sound that great right away. I've only had them playing for about a half hour so far.
Well, I jumped the gun and decided to remove the resistors anyway. Yuck!
Everything is muddy and cupped. I just reversed the polarity on the Alpairs to see if it would help... It didn't.
I still have the Erse 3mH air-core across the Alpair, the 51uF Solen cap across the woofer, and the "unknown" iron-core on the + of the woofer. I still have the polarity reversed on the Alpairs.
Any ideas? Do the Alpairs just need to break-in again? Should I leave them as is at the moment and see what happens? Is it typical of these drivers to be rather dull on the top end at first? They really do sound nasty right now.
The reason I decided to do this is simply because I figured since I already have all of the proper drivers and enclosures, I might as well get them running and start playing around with some x-over tuning.
Everything is muddy and cupped. I just reversed the polarity on the Alpairs to see if it would help... It didn't.
I still have the Erse 3mH air-core across the Alpair, the 51uF Solen cap across the woofer, and the "unknown" iron-core on the + of the woofer. I still have the polarity reversed on the Alpairs.
Any ideas? Do the Alpairs just need to break-in again? Should I leave them as is at the moment and see what happens? Is it typical of these drivers to be rather dull on the top end at first? They really do sound nasty right now.
The reason I decided to do this is simply because I figured since I already have all of the proper drivers and enclosures, I might as well get them running and start playing around with some x-over tuning.
Hmm...
These sure haven't improved at all over the past 24 hours except that they have regained the treble that they were severely lacking last night. There's still a gap/thinness in the midrange, giving that cupped sound.
Should I remove the iron-core on the woofers and put the polarity of the 10.2's back in phase?
These sure haven't improved at all over the past 24 hours except that they have regained the treble that they were severely lacking last night. There's still a gap/thinness in the midrange, giving that cupped sound.
Should I remove the iron-core on the woofers and put the polarity of the 10.2's back in phase?
Hi Bob,
Yes, it's a series x-over. I have not modeled it and not sure that I know how. The iron-core inductor was added for better phase response I was told for the woofer, also making it a 2nd order. The Alpair uses an Erse 3mH air-core across it. The 10 ohm resistor was for leveling the Fostex, which I removed when I swapped to the Alpair.
Also, thanks for joining in on the topic!
Yes, it's a series x-over. I have not modeled it and not sure that I know how. The iron-core inductor was added for better phase response I was told for the woofer, also making it a 2nd order. The Alpair uses an Erse 3mH air-core across it. The 10 ohm resistor was for leveling the Fostex, which I removed when I swapped to the Alpair.
Also, thanks for joining in on the topic!
I don't know if people are just busy doing other things or avoiding me or avoiding this project, but...
Just a few minutes ago, I removed the iron-core from the circuit and wired the Alpair back in phase, so it's now like this...
Vifa with 51uF Solen across its VC
Alpair with 3mH Erse air-core across its VC
Both drivers wired in phase
The speakers NOW sound really good. Great blend between both drivers, great matching levels between drivers, the Vifa's now extend up higher to match the low end roll off of the Alpair's.
With little to no gap between the drivers now, there's a good sound stage again as well as good imaging. I'm saying "good" only because I'm playing the system at whisper levels as the kids are in bed.
Vocals sounds a lot fuller and natural, not thin and disconnected. Instruments sound real, bass is still tight and detailed. Treble is smooth and detailed for the most part, but just slightly recessed compared to the little Fostex FE103e drivers. However, that could also be a result of the older recordings I'm listening to right now on "Inside Jazz Straight Up" via internet radio through the Marantz.
With these very enlightening results, I'm now getting excited about my new project again as it will be using the same basic drivers/x-over design. This is a great proof of concept.
Now I need to figure out where to go from here. Should I consider implementing a zobel network on either driver, or both drivers?
Any other suggestions short of building the new enclosures with new, wider dimensions?
Just a few minutes ago, I removed the iron-core from the circuit and wired the Alpair back in phase, so it's now like this...
Vifa with 51uF Solen across its VC
Alpair with 3mH Erse air-core across its VC
Both drivers wired in phase
The speakers NOW sound really good. Great blend between both drivers, great matching levels between drivers, the Vifa's now extend up higher to match the low end roll off of the Alpair's.
With little to no gap between the drivers now, there's a good sound stage again as well as good imaging. I'm saying "good" only because I'm playing the system at whisper levels as the kids are in bed.
Vocals sounds a lot fuller and natural, not thin and disconnected. Instruments sound real, bass is still tight and detailed. Treble is smooth and detailed for the most part, but just slightly recessed compared to the little Fostex FE103e drivers. However, that could also be a result of the older recordings I'm listening to right now on "Inside Jazz Straight Up" via internet radio through the Marantz.
With these very enlightening results, I'm now getting excited about my new project again as it will be using the same basic drivers/x-over design. This is a great proof of concept.
Now I need to figure out where to go from here. Should I consider implementing a zobel network on either driver, or both drivers?
Any other suggestions short of building the new enclosures with new, wider dimensions?
Abandonment of this thread or not, I'm still going to post some findings, one of which I'm hearing right now...
I'm listening to Linn Classical on internet radio via the Marantz receiver. I'm in the bedroom, so hearing the music playing down the 20' long hallway. There's a piano playing with a string quartet and the piano sounds like it's literally in the family room.
I can clearly hear and sense the heft and body of the piano in the lower register, the very natural uncolored tone of the mid and upper register, even the tactile effect (bite) of the hammers striking the strings. It truly does sound like the real deal down there at the other end of the hallway.
The string quartet sounds pretty darn lifelike as well, dynamic, quick, agile. It's almost like standing backstage listening to a live performance. The NHT's and Polk's were never capable of such a thing.
With the project in mind, I was thinking about going with a wider baffle to get the baffle step lower so I could get the x-over point of the 10.2 lower, but now I'm not sure. The retro-fitted speakers that I'm working with are using the simplest possible x-over design (just two components) and they sound "this" good already. With just a few other tweaks to make with a new prototype pair of enclosures and these drivers, I may just have the next giant killer.
I'm listening to Linn Classical on internet radio via the Marantz receiver. I'm in the bedroom, so hearing the music playing down the 20' long hallway. There's a piano playing with a string quartet and the piano sounds like it's literally in the family room.
I can clearly hear and sense the heft and body of the piano in the lower register, the very natural uncolored tone of the mid and upper register, even the tactile effect (bite) of the hammers striking the strings. It truly does sound like the real deal down there at the other end of the hallway.
The string quartet sounds pretty darn lifelike as well, dynamic, quick, agile. It's almost like standing backstage listening to a live performance. The NHT's and Polk's were never capable of such a thing.
With the project in mind, I was thinking about going with a wider baffle to get the baffle step lower so I could get the x-over point of the 10.2 lower, but now I'm not sure. The retro-fitted speakers that I'm working with are using the simplest possible x-over design (just two components) and they sound "this" good already. With just a few other tweaks to make with a new prototype pair of enclosures and these drivers, I may just have the next giant killer.
Chops - exactly how did you calculate the circuit values for your series XO?
I normally don't do this at all - i.e. rely on other folk's math -, and on recent 2-way systems have been able to use my AV receivers dsp for digital crossover function. There are tons of passive XO calculators extant, but how about for series?
I normally don't do this at all - i.e. rely on other folk's math -, and on recent 2-way systems have been able to use my AV receivers dsp for digital crossover function. There are tons of passive XO calculators extant, but how about for series?
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