Merry Christmas!
Happy Holidays to all.
Here's a little something that Gary Dahl did recently:
https://www.youtube.com/watch?v=-a9p_GQmDx4
Enjoy,
TerryO
Happy Holidays to all.
Here's a little something that Gary Dahl did recently:
https://www.youtube.com/watch?v=-a9p_GQmDx4
Enjoy,
TerryO
Hi everyone,
Thanks to Lynn Olson and every contributors of interest for this tremendous post. It's quite a thing to join it at page 1401... Like we said in french: "Vaut mieux tard que jamais." I read many pages of it in the last week, mainly because I consider the use of a GPA 416-8B for an eventual projet of a bass-reflex enclosure. I found a lot of interesting informations on this thread.
This said, one question pops my mind, while the project tends to use the woofers in the 70Hz to 700Hz region. Did you compared GPA 414-8B sonic qualities in that range versus GPA 416 and 515? If so, what was the conclusion?
Thanks,
Sébastien
Thanks to Lynn Olson and every contributors of interest for this tremendous post. It's quite a thing to join it at page 1401... Like we said in french: "Vaut mieux tard que jamais." I read many pages of it in the last week, mainly because I consider the use of a GPA 416-8B for an eventual projet of a bass-reflex enclosure. I found a lot of interesting informations on this thread.
This said, one question pops my mind, while the project tends to use the woofers in the 70Hz to 700Hz region. Did you compared GPA 414-8B sonic qualities in that range versus GPA 416 and 515? If so, what was the conclusion?
Thanks,
Sébastien
The Altec/GPA 414 is a first-class driver, particularly in the midrange. Some consider it one of the best midrange drivers ever made.
But ... based on the independently measured T/S data I've seen, the 414 is about 2 dB less efficient than the 416. In other words, the 12" 414 comes in around 95.5 dB/meter, while the 15" 416 comes in around 97.5 dB/meter, and the 515 comes in around 99 dB/meter.
So a pair of 414's is a bit less than a single 515 in terms of efficiency, and a little bigger in radiating area. The required closed-box volume for a pair is 416's is about the same as a single 416, about 3.5 cubic feet, or 99 liters.
A very possible arrangement that avoids the construction hassle of a bass horn is a pair of side-by-side 416's, working in the 80~800 Hz range (Q=0.707 closed-box alignment), with one or two LF drivers placed directly below, and taking advantage of the floor image for an efficiency gain and gain in power-handling.
I'm not sure about the subjective qualities of a small array of direct-radiator bass drivers versus a compact bass horn (covering the 180~800 Hz range). Both are more directional than a single 12 or 15-inch driver, and both have improved efficiency and increased power-handling compared to single-driver direct-radiators.
Subjectively? Bass horns have a very distinctive quality compared to direct-radiators, and are an obvious match for a MF/HF horn. But the sound of an array? I don't know. Other folks are very welcome to add their thoughts.
One thing that sets a bass horn apart from direct radiators (in conventional bass enclosures) is useful directivity in a frequency region where room modes become troublesome. Interestingly, they share the property of increased LF directivity with electrostats and open-baffle speakers, although with much greater power-handling and headroom. This is probably the reason that all three types are known for increased clarity and "snap" in the upper and mid-bass region.
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I read the 12" bass Altec/GPA 414 blurb with interest, Lynn.
http://www.greatplainsaudio.com/downloads/414-8B%20Spec%20Sheet.pdf
It seems to do everything right. High mechanical Qms of 7.5 in accordance with current enthusiasm for low mechanical loss and high efficiency. Fibre cone. Presumably not a lossy slit aluminium former. A dustcap with a hole. We don't mind cloth surrounds. Some nonsense about quantum mechanics and AlNiCo, but if AlNiCo has an internal damping factor, I can buy that.
Of course, this cheapie ferrite magnet Sony E44 bass does much the same, even if the Morel soft dome tweeter was a bit of a failure. I like it. The cloth dustcap is just that, not a solid piece of paper.
Here's my current second-order design. It has a quite remarkable sound. Sort of slows down the music and makes you listen to the vocal. It's my best ever variation on the theme, and as you know I can do LR2, BW3 and LR4. Of course I can hear the hole in the power response at crossover, but that's even order filters for you.
I've got something extremely right here, though I say so myself.
See, I'm just adding a tiny bit of damping to the midbass in the midrange, and getting the tweeter impedance from going high in the ultrasonic and improving Solid state amplifier stability. So MAYBE, I'm simulating an AlNiCo magnet and valve sound here? And, of course, I do know what valves sound like, having owned a Radford STA-25.
http://www.greatplainsaudio.com/downloads/414-8B%20Spec%20Sheet.pdf
It seems to do everything right. High mechanical Qms of 7.5 in accordance with current enthusiasm for low mechanical loss and high efficiency. Fibre cone. Presumably not a lossy slit aluminium former. A dustcap with a hole. We don't mind cloth surrounds. Some nonsense about quantum mechanics and AlNiCo, but if AlNiCo has an internal damping factor, I can buy that.
Of course, this cheapie ferrite magnet Sony E44 bass does much the same, even if the Morel soft dome tweeter was a bit of a failure. I like it. The cloth dustcap is just that, not a solid piece of paper.
Here's my current second-order design. It has a quite remarkable sound. Sort of slows down the music and makes you listen to the vocal. It's my best ever variation on the theme, and as you know I can do LR2, BW3 and LR4. Of course I can hear the hole in the power response at crossover, but that's even order filters for you.
I've got something extremely right here, though I say so myself.
See, I'm just adding a tiny bit of damping to the midbass in the midrange, and getting the tweeter impedance from going high in the ultrasonic and improving Solid state amplifier stability. So MAYBE, I'm simulating an AlNiCo magnet and valve sound here? And, of course, I do know what valves sound like, having owned a Radford STA-25.
My guess about the Alnico "sound" ... and it is a guess ... is that flux variations created by voice coil currents are reflected back into the magnet, and the pole-piece and magnet acts as a somewhat nonlinear iron-core (or ferrite) choke that's always in the signal path. This is where a magnetically saturated gap can be useful; since the gap structure is close to saturation, audio-frequency flux variations are (mostly) prevented from reaching the magnet, and remain in the pole-piece and gap structure. My understanding is the Alnico 414, 416, and 515 have gap structures that are close to saturation, in addition to underhung voice coils and the traditional Alnico magnets. With field-coils, of course, you can crank up the power until the gap structure is completely saturated.
It's easy to forget that Alnico was the de facto standard in the Forties, Fifties, and early Sixties, even in cheap table-radio and TV speakers. It was nothing special. It was used because it worked, and was obviously more practical than prewar-style field-coils. Underhung voice coils were also pretty common until powerful amps required bass drivers with long excursions that were in small boxes. In the days before T/S theory and computer-modeled crossovers, there was an advantage if drivers were constructed with paper cones with good internal self-damping. They measured better and sounded better.
I'm a little surprised that magnet and gap construction is audible at all; it's not anything that I expected. I used to think that cone and surround construction, selection of glues, and a linear BL product were the whole story.
It's easy to forget that Alnico was the de facto standard in the Forties, Fifties, and early Sixties, even in cheap table-radio and TV speakers. It was nothing special. It was used because it worked, and was obviously more practical than prewar-style field-coils. Underhung voice coils were also pretty common until powerful amps required bass drivers with long excursions that were in small boxes. In the days before T/S theory and computer-modeled crossovers, there was an advantage if drivers were constructed with paper cones with good internal self-damping. They measured better and sounded better.
I'm a little surprised that magnet and gap construction is audible at all; it's not anything that I expected. I used to think that cone and surround construction, selection of glues, and a linear BL product were the whole story.
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Thanks Lynn,
As always your posts are both interesting and informative,I am particularly interested in your recent posts.
Re the audible differences between various motor designs I suspect that when using used drivers and or new stock drivers manufacturing tolerance plays a big part in audible differences.
In order to accurately identify if differences were audible it would cost thousands of $$$$ ie one would have to OEM your test drivers to a very tight spec and then carefully compare identical drivers with only one change per batch to identify any differences, then be able to repeat the tests with a second and third batch with consistent results.....
Given all the gap / wire / magnet / former / coil variables a formidable task!
Thanks again for sharing your thoughts and valuable experience.
All the best
Derek.
As always your posts are both interesting and informative,I am particularly interested in your recent posts.
Re the audible differences between various motor designs I suspect that when using used drivers and or new stock drivers manufacturing tolerance plays a big part in audible differences.
In order to accurately identify if differences were audible it would cost thousands of $$$$ ie one would have to OEM your test drivers to a very tight spec and then carefully compare identical drivers with only one change per batch to identify any differences, then be able to repeat the tests with a second and third batch with consistent results.....
Given all the gap / wire / magnet / former / coil variables a formidable task!
Thanks again for sharing your thoughts and valuable experience.
All the best
Derek.
In subjective terms, the Alnico drivers (regardless whether they are Altec, Lowther, Feastrex, or TAD bass drivers) have a distinctive "nickel-core transformer" sound, compared to a transformer with a conventional M6 (silicon steel) core. That's a difference that is meaningful for those of us who play with building our own tube amps from scratch, and have done transformer swaps while subjectively balancing the amplifier.
For a consumer that buys amps as-is, this is not a meaningful or helpful description. Pre-built consumer amps are essentially black boxes, particularly if the consumer has little idea of what's in the box, or what those mysterious parts do.
I'm not sure that ceramic vs Alnico vs field-coil difference is even audible with transistor amps. I have no idea. Nelson Pass designs single-ended MOSFET amplifiers, and is a Lowther enthusiast, so he's the person to ask, not me. My transistor-amp experience is mostly casual listening to my Marantz home-theater setup with AAC-compressed audio from AppleTV (optical out) or other mid-fi streaming sources.
If I'm in the mood for "serious" listening ... maybe not the right word, but you get the idea ... I fire up the 2-channel all-tube rig with the Burr-Brown DACs, Audio-GD DI-2014 reclocker and USB converter, and Marantz Blu-Ray disc spinner and SACD and DVD-A source. The external crossovers for the Ariels have changeover switches with isolated grounds so the switchover between the two systems can be done in less than a minute.
In terms of driving experience, as it were, it's the difference between a Prius and a Jaguar. They both get you there, from A to B, but it sure feels different when you're behind the wheel.
For a consumer that buys amps as-is, this is not a meaningful or helpful description. Pre-built consumer amps are essentially black boxes, particularly if the consumer has little idea of what's in the box, or what those mysterious parts do.
I'm not sure that ceramic vs Alnico vs field-coil difference is even audible with transistor amps. I have no idea. Nelson Pass designs single-ended MOSFET amplifiers, and is a Lowther enthusiast, so he's the person to ask, not me. My transistor-amp experience is mostly casual listening to my Marantz home-theater setup with AAC-compressed audio from AppleTV (optical out) or other mid-fi streaming sources.
If I'm in the mood for "serious" listening ... maybe not the right word, but you get the idea ... I fire up the 2-channel all-tube rig with the Burr-Brown DACs, Audio-GD DI-2014 reclocker and USB converter, and Marantz Blu-Ray disc spinner and SACD and DVD-A source. The external crossovers for the Ariels have changeover switches with isolated grounds so the switchover between the two systems can be done in less than a minute.
In terms of driving experience, as it were, it's the difference between a Prius and a Jaguar. They both get you there, from A to B, but it sure feels different when you're behind the wheel.
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Good morning everyone,
Lynn, a better efficiency was my main hypothesis regarding your choice of the 416/515 combo. If I reformulate my question, it should be understand as: did you sacrifice any musical qualities by choosing efficiency of the 416/515 combo over 414 midrange qualities or you were able to compared them sonicly and prefer the first combo over the later?
"Sébastien, why do you ask me all this question?" Well, I already have my petites Onken using the 414:
http://www.diyaudio.com/forums/multi-way/253853-la-petite-onken-15.html#post4590517
But, I want to know more of 416's qualities in the midrange before moving forward in a projet using GPA 416.
Now, regarding the double 416 option, it reminds me of the Onken W. Plus, a double 414 speakers was also done by Altec before. But if I understand, one of your original goal with the use in closed box and subwoofer below was to get a relatively "small" speaker's footprint. Which is no more the case with bass-reflex enclosure.
Finally, I'm wondering how did you finally arrange a perfect time alignment of the different emissive sources in your set-up. Did you do it numerically?
Have a good day,
Sébastien
Lynn, a better efficiency was my main hypothesis regarding your choice of the 416/515 combo. If I reformulate my question, it should be understand as: did you sacrifice any musical qualities by choosing efficiency of the 416/515 combo over 414 midrange qualities or you were able to compared them sonicly and prefer the first combo over the later?
"Sébastien, why do you ask me all this question?" Well, I already have my petites Onken using the 414:
http://www.diyaudio.com/forums/multi-way/253853-la-petite-onken-15.html#post4590517
But, I want to know more of 416's qualities in the midrange before moving forward in a projet using GPA 416.
Now, regarding the double 416 option, it reminds me of the Onken W. Plus, a double 414 speakers was also done by Altec before. But if I understand, one of your original goal with the use in closed box and subwoofer below was to get a relatively "small" speaker's footprint. Which is no more the case with bass-reflex enclosure.
Finally, I'm wondering how did you finally arrange a perfect time alignment of the different emissive sources in your set-up. Did you do it numerically?
Have a good day,
Sébastien
Sébastien, you have a beautiful setup that looks pretty close to Gary Dahl's rig in refinement and quality. I'd leave it alone unless there is some aspect to the performance you want to enhance or extend. From where you are now (based on the pictures), further improvements will come at a substantial cost in complexity, size, expense, and development time.
For example, you might contemplate a single 416 for the deep and middle bass (enclosure type up to you), and retain the 414 for the mids (the 414 could be moved to a much smaller closed-box, or you could experiment with a dipole baffle). To get around efficiency mismatches, you might have a separate amplifier for the 416 bass section, of the same general Kaneda design you're already using for the existing speakers. A simple RC line-level crossover should take care of frequency-division chores between the two amplifiers. In a system of this quality, I would avoid active crossovers with op-amps, or digital crossovers.
If you choose to go this route, the 414 can go in a closed box that produces a Q = 0.707 (2nd-order Butterworth highpass). At a guess, that's a fiber-filled box about 1.75 cubic feet or 50 liters (quite small compared to the Petite Onken). You might want to retain the existing baffle width, or possibly round over the left and right edges.
Although there's no gain in efficiency (compared to the existing speaker), the Kaneda amp has plenty of power for this application, so that's not important. What is important is a substantial reduction in IM distortion and gain in overall headroom, thanks to reduction of excursion in the 414, since it is no longer asked to do deep bass. This is particularly important for short-throw underhung Altec drivers, which don't like to move very much. The Altecs that sound the best are the ones where you don't see the cone moving.
The 416 is known for its tonality and even balance between deep bass and midrange, and is a natural complement to the 414. Since the drivers have similar tonality, this simplifies the crossover, and gets rid of a potentially awkward transition in the midbass region. Intentional overlap between the two is perfectly acceptable and can be used to tune the system to the room (measurements required, though).
For example, you might contemplate a single 416 for the deep and middle bass (enclosure type up to you), and retain the 414 for the mids (the 414 could be moved to a much smaller closed-box, or you could experiment with a dipole baffle). To get around efficiency mismatches, you might have a separate amplifier for the 416 bass section, of the same general Kaneda design you're already using for the existing speakers. A simple RC line-level crossover should take care of frequency-division chores between the two amplifiers. In a system of this quality, I would avoid active crossovers with op-amps, or digital crossovers.
If you choose to go this route, the 414 can go in a closed box that produces a Q = 0.707 (2nd-order Butterworth highpass). At a guess, that's a fiber-filled box about 1.75 cubic feet or 50 liters (quite small compared to the Petite Onken). You might want to retain the existing baffle width, or possibly round over the left and right edges.
Although there's no gain in efficiency (compared to the existing speaker), the Kaneda amp has plenty of power for this application, so that's not important. What is important is a substantial reduction in IM distortion and gain in overall headroom, thanks to reduction of excursion in the 414, since it is no longer asked to do deep bass. This is particularly important for short-throw underhung Altec drivers, which don't like to move very much. The Altecs that sound the best are the ones where you don't see the cone moving.
The 416 is known for its tonality and even balance between deep bass and midrange, and is a natural complement to the 414. Since the drivers have similar tonality, this simplifies the crossover, and gets rid of a potentially awkward transition in the midbass region. Intentional overlap between the two is perfectly acceptable and can be used to tune the system to the room (measurements required, though).
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Hi,
I think that there is several competitive solutions
1 - Keep the system "as is" and try to improve the amplifiers (if possible) and the other parts, but I think that Sebastien has pretty nice elements.
2 - Go to a 15", this is my choice (I use a GPA 515-8C in a 320 liters enclosure, and a TD2001 with a 4 cells "Ledauphin" horn), it may be, in my opinion, an upgrade in several fields, thanks to the ability to Sebastien's horns to go to 800 Hz or perhaps 600 Hz, the 15" will not be a problem.
3 - Go to "perhaps a dream"
- 416-8B in bass
- 414-8B in low mid
- 1" driver
- Tweeter
.... this is a little bit like a JBL 4345 but with Altec bass speakers, may be interesting, but I don't think that Sebastien has enough room space to do it.
But it is nice to dream....
Andre
I think that there is several competitive solutions
1 - Keep the system "as is" and try to improve the amplifiers (if possible) and the other parts, but I think that Sebastien has pretty nice elements.
2 - Go to a 15", this is my choice (I use a GPA 515-8C in a 320 liters enclosure, and a TD2001 with a 4 cells "Ledauphin" horn), it may be, in my opinion, an upgrade in several fields, thanks to the ability to Sebastien's horns to go to 800 Hz or perhaps 600 Hz, the 15" will not be a problem.
3 - Go to "perhaps a dream"
- 416-8B in bass
- 414-8B in low mid
- 1" driver
- Tweeter
.... this is a little bit like a JBL 4345 but with Altec bass speakers, may be interesting, but I don't think that Sebastien has enough room space to do it.
But it is nice to dream....
Andre
Thanks Lynn,
Ultimately, I see two things to "enhance and extend". First, the sensitivity. The option of an Onken 4550 (2 x 416 per channel) crossed my mind. I must admit that I appreciate a lot the Onken way and what Eijiro Koïzumi created while having this company. Unfortunately, I do not have the space for this. Plus, it would needs a 4th way: the low-mid.
The other point, is to get a bit more "deeper" bass response. But it seems there could/probably be more. Someone in France who knows about GPA and uses them, told me I could get more punch, dynamics, weight and bass, of course with the GPA 416. What is interesting, is that this guy took the exact dimensions of petite Onken's face and draw an enclosure just a bit deeper to obtain 220L (8.8 ft) for a good match with the GPA 416 in a classic bass-reflex design tuned at 29 Hz like an example on GPA 416-8B specs sheet:
http://www.greatplainsaudio.com/downloads/416-8B Spec Sheet.pdf
Actually, this is what I am considering. Well, it is a bit off topic. Maybe it will be a good idea to created a "Beyond la petite Onken" thread to discuss more of that.
This said, while I was hesitating whether using original Altec 416 or GPA 416, Beyond the Ariel's thread gave me the confirmation to move forward with the GPA option. Which I should repeat, I already have GPA 414 and love them.
Sébastien
Ultimately, I see two things to "enhance and extend". First, the sensitivity. The option of an Onken 4550 (2 x 416 per channel) crossed my mind. I must admit that I appreciate a lot the Onken way and what Eijiro Koïzumi created while having this company. Unfortunately, I do not have the space for this. Plus, it would needs a 4th way: the low-mid.
The other point, is to get a bit more "deeper" bass response. But it seems there could/probably be more. Someone in France who knows about GPA and uses them, told me I could get more punch, dynamics, weight and bass, of course with the GPA 416. What is interesting, is that this guy took the exact dimensions of petite Onken's face and draw an enclosure just a bit deeper to obtain 220L (8.8 ft) for a good match with the GPA 416 in a classic bass-reflex design tuned at 29 Hz like an example on GPA 416-8B specs sheet:
http://www.greatplainsaudio.com/downloads/416-8B Spec Sheet.pdf
Actually, this is what I am considering. Well, it is a bit off topic. Maybe it will be a good idea to created a "Beyond la petite Onken"
thread to discuss more of that.This said, while I was hesitating whether using original Altec 416 or GPA 416, Beyond the Ariel's thread gave me the confirmation to move forward with the GPA option. Which I should repeat, I already have GPA 414 and love them.
Sébastien
Solutions 2 and 3 look really good. Rumor has it the Kaneda is the best transistor amp ever made, and is on the same performance level as high-quality direct-heater-triode amplifiers ... which is really saying something. In other words, leave it alone!
Be very very careful not lose the tonal balance or the overall quality of "wholeness" that really good 2-way systems have. It's something I treasure about my 22-year-old Ariels, or what I hear in a first-class Altec system. The greatest and most terrible aspect of an overly complex high-end loudspeaker is they sound disjointed, or the sound is only really balanced at one listening level, and not-right everywhere else. This is most severe with loudspeakers with really dissimilar technologies for different parts of the spectrum.
Be very very careful not lose the tonal balance or the overall quality of "wholeness" that really good 2-way systems have. It's something I treasure about my 22-year-old Ariels, or what I hear in a first-class Altec system. The greatest and most terrible aspect of an overly complex high-end loudspeaker is they sound disjointed, or the sound is only really balanced at one listening level, and not-right everywhere else. This is most severe with loudspeakers with really dissimilar technologies for different parts of the spectrum.
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