Well, here's André. The guy I was talking about. He just send is message while I was writing my last one. 
Nice to see you here André,
Sébastien
Nice to see you here André,
Sébastien
Here are the T/S measurements made by Drivervault (a neighbor who measured my 414 Alnicos from GPA) and Gary Dahl's measurements of his 416's and 515's. Note these are not the same as measurements made of "classic" Altecs. For better or worse, Altec changed their drivers on a fairly frequent basis, so there is no "one" 414, 416, or 515.
https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/gpa-altec-414
GPA 414-16B Alnico (s/n 0608-0006)
Fs = 24.688 Hz
Re = 11.9 ohms[dc]
Le = 2430 uH
Qt = 0.2193
Qes = 0.2377
Qms = 2.8341
Mms = 44.972 grams
Vas = 326.13 liters
Sd= 502.725 cm^2
Bl = 18.688 Wb/m
Lp(2.83V/1m) = 93.69 dB (for 16-ohm driver)
GPA 416-8B Alnico (s/n 0229) after 60-minute break-in. Added mass method, 52 grams.
The other 416-8B Alnico was essentially identical, so measurements are omitted.
Fs = 21.45 Hz
Re = 6.60 ohms[dc]
Le = 1302.62 uH
L2 = 1224.79 uH
R2 = 19.79 ohms
Qt = 0.27
Qes = 0.28
Qms = 8.32
Mms = 67.20 grams
Rms = 1.088135 kg/s
Cms = 0.000819 m/N
Vas = 782.20 liters
Sd= 824.48 cm^2
Bl = 14.649466 Tm
ETA = 2.66 %
Lp(2.83V/1m) = 97.20 dB (for 8-ohm driver)
Here's one GPA 515-16C Alnico (s/n: 0201)
Fs = 19.67 Hz
Re = 10.10 ohms[dc]
Le = 2014.44 uH
L2 = 1700.26 uH
R2 = 26.35 ohms
Qt = 0.23
Qes = 0.24
Qms = 6.65
Mms = 66.31 grams
Rms = 1.231868 kg/s
Cms = 0.000987 m/N
Vas = 942.50 liters
Sd= 824.48 cm^2
Bl = 18.641369 Tm
ETA = 2.90 %
Lp(2.83V/1m) = 95.71 dB (for 16-ohm driver)
Added mass = 52.00 grams
And the other 515-16C Alnico (s/n: 0202)
Fs = 17.76 Hz
Re = 10.10 ohms[dc]
Le = 1560.53 uH
L2 = 1554.85 uH
R2 = 26.22 ohms
Qt = 0.20
Qes = 0.20
Qms = 7.33
Mms = 71.83 grams
Rms = 1.093800 kg/s
Cms = 0.001118 m/N
Vas = 1067.21 liters
Sd= 824.48 cm^2
Bl = 20.039295 Tm
ETA = 2.85 %
Lp(2.83V/1m) = 95.64 dB (for 16-ohm driver)
Added mass = 52.00 grams
https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/gpa-altec-414
GPA 414-16B Alnico (s/n 0608-0006)
Fs = 24.688 Hz
Re = 11.9 ohms[dc]
Le = 2430 uH
Qt = 0.2193
Qes = 0.2377
Qms = 2.8341
Mms = 44.972 grams
Vas = 326.13 liters
Sd= 502.725 cm^2
Bl = 18.688 Wb/m
Lp(2.83V/1m) = 93.69 dB (for 16-ohm driver)
GPA 416-8B Alnico (s/n 0229) after 60-minute break-in. Added mass method, 52 grams.
The other 416-8B Alnico was essentially identical, so measurements are omitted.
Fs = 21.45 Hz
Re = 6.60 ohms[dc]
Le = 1302.62 uH
L2 = 1224.79 uH
R2 = 19.79 ohms
Qt = 0.27
Qes = 0.28
Qms = 8.32
Mms = 67.20 grams
Rms = 1.088135 kg/s
Cms = 0.000819 m/N
Vas = 782.20 liters
Sd= 824.48 cm^2
Bl = 14.649466 Tm
ETA = 2.66 %
Lp(2.83V/1m) = 97.20 dB (for 8-ohm driver)
Here's one GPA 515-16C Alnico (s/n: 0201)
Fs = 19.67 Hz
Re = 10.10 ohms[dc]
Le = 2014.44 uH
L2 = 1700.26 uH
R2 = 26.35 ohms
Qt = 0.23
Qes = 0.24
Qms = 6.65
Mms = 66.31 grams
Rms = 1.231868 kg/s
Cms = 0.000987 m/N
Vas = 942.50 liters
Sd= 824.48 cm^2
Bl = 18.641369 Tm
ETA = 2.90 %
Lp(2.83V/1m) = 95.71 dB (for 16-ohm driver)
Added mass = 52.00 grams
And the other 515-16C Alnico (s/n: 0202)
Fs = 17.76 Hz
Re = 10.10 ohms[dc]
Le = 1560.53 uH
L2 = 1554.85 uH
R2 = 26.22 ohms
Qt = 0.20
Qes = 0.20
Qms = 7.33
Mms = 71.83 grams
Rms = 1.093800 kg/s
Cms = 0.001118 m/N
Vas = 1067.21 liters
Sd= 824.48 cm^2
Bl = 20.039295 Tm
ETA = 2.85 %
Lp(2.83V/1m) = 95.64 dB (for 16-ohm driver)
Added mass = 52.00 grams
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Thanks for these T/S measurements, it is really nice.
If I use one set of parameters for a GPA 515-16C Alnico, with my sparkers simulations, 320 liters @ 34 Hz tuning, I have really close results to what I measure in real, about 35 Hz, -3dB response
Regards
Andre
If I use one set of parameters for a GPA 515-16C Alnico, with my sparkers simulations, 320 liters @ 34 Hz tuning, I have really close results to what I measure in real, about 35 Hz, -3dB response
Regards
Andre
Attachments
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Lynn, in my research in that post this week I saw and refered a few times to 515 and 416's T/S parameters you put back. Thanks, it will be easier to find them back.
Now it surprises me that the sensitivity of the 416 is higher than the 515 ?! I thought it was the opposite. If we consider an improvement of almost 4 dB from the 414 to the 416, it's even better than the original +2dB I expected.
André, on those simulations response as in your graph above, does it correspond to a near field measure? In the end, the response which I'm interested in is the one at the listening position.
Sébastien
Now it surprises me that the sensitivity of the 416 is higher than the 515 ?! I thought it was the opposite. If we consider an improvement of almost 4 dB from the 414 to the 416, it's even better than the original +2dB I expected.
André, on those simulations response as in your graph above, does it correspond to a near field measure? In the end, the response which I'm interested in is the one at the listening position.
Sébastien
Sadly, so true
and why I don't recommend buying these used unless you know for sure from detailed measurements just what you're getting. Better to buy new GPA or another brand's similar 12-15" mid-bass horn or reflex optimized HE driver. FWIW, my [4] '50s matched 515B [two ~new sequential SNs and two much older frames I had re-coned to match] average ~ 20 Hz Fs, 0.2 Qts, 20 ft^3 Vas, but compared to several different sets of progressively newer pairs up to the mid '80s; the major sonic difference was their HF response, with each becoming more like a 416, which resulted in increasingly poor match-up to my custom 210s [huge dip in its mid-band response and increasingly better suited to the 'small' 825/828, etc., horn, which was 'corrected' back to ~original /mine with the 515-8G as shown in the bottom response plot and not so well in the others: http://www.lansingheritage.org/images/altec/specs/components/515g/page3.jpg
GM
Sadly, so true
That's exactly what I'm saying since a lot of time in French forums, but the church of the old Altec at any price is powerful....
You can buy an old driver, only if you know exacetly what you're doing, and if you can control the behavior of the speakers.... but sometimes, it is speaking in the desert....
Regards
Andre
So true, but we still have to try, right? Then again, it's in those folks best interest with highly collectible ones to promote them for that time when they either must sell for whatever reason or bequeath to others. Me and a few others really screwed up when we posted on-line about which brands, models were still worth having back in ebay's, etc., early days as almost immediately the prices skyrocketed from yard sale [near] giveaway to the ridiculous with buyers willing to pay them, so consequently has mostly stayed there plus gave the !@#$%^&*()_+ folks enough info to scam the uninformed 'big time'.
Sure wish I'd been smart enough to get them before 'shooting my mouth [and foot] off' since there's no way I can ever afford them now.
GM
Sure wish I'd been smart enough to get them before 'shooting my mouth [and foot] off' since there's no way I can ever afford them now.
GM
Sebastien,
I have been looking for answers to your questions too. All three drivers seem to have a great midrange (some say the 414 and 515 are a little better on the midrange), while it is more or less accepted that the 416 works better on the lows than the 414. For me it was a choice between the 414 and the 416 because the 515 would need an even bigger enclosure.
I have bought the GPA 416-8B and will start building cabinets soon. Sooner or later I will order the GPA 414, either to try a smaller HE 2 way or to a three way system.
A fourth solution for you to try could be to keep your system's components, but to use the 414 in a smaller enclosure only down to ~70-80 Hz. Below that, use a couple of 10" or 12" modern drivers in small sealed boxes distributed in your room. This would accomplish several things, 1) much smaller footprint of the main speakers, 2) better behavior/interaction with the room in the low freq. You can check the Audiokinesis Swarn subs.
Two questions: did you modify the volume of the petit onken to use the GPA 414-8B? Was the volume suggested to you for the onken type cab for the 416 based on the GPA 416-8B?
I have been looking for answers to your questions too. All three drivers seem to have a great midrange (some say the 414 and 515 are a little better on the midrange), while it is more or less accepted that the 416 works better on the lows than the 414. For me it was a choice between the 414 and the 416 because the 515 would need an even bigger enclosure.
I have bought the GPA 416-8B and will start building cabinets soon. Sooner or later I will order the GPA 414, either to try a smaller HE 2 way or to a three way system.
A fourth solution for you to try could be to keep your system's components, but to use the 414 in a smaller enclosure only down to ~70-80 Hz. Below that, use a couple of 10" or 12" modern drivers in small sealed boxes distributed in your room. This would accomplish several things, 1) much smaller footprint of the main speakers, 2) better behavior/interaction with the room in the low freq. You can check the Audiokinesis Swarn subs.
Two questions: did you modify the volume of the petit onken to use the GPA 414-8B? Was the volume suggested to you for the onken type cab for the 416 based on the GPA 416-8B?
Any GP drivers in UK?
Hi All,
If anyone has or knows of any GP drivers in a UK system I would very much like to compare the GP with the Precision Devices 158 attached.
As I use a DEQX I can match the crossover points to whatever the GP drivers use to try and level the playing field.
Thanks
Derek.
Hi All,
If anyone has or knows of any GP drivers in a UK system I would very much like to compare the GP with the Precision Devices 158 attached.
As I use a DEQX I can match the crossover points to whatever the GP drivers use to try and level the playing field.
Thanks
Derek.
I should add there is a bit of variation in current-production GPA drivers. Before anyone gets all upset about this, it's an old Altec tradition. Look at any bunch of old Altecs, sometimes with consecutive serial numbers, and you'll find variations. I was surprised to open up the fancy cast-aluminum crossover boxes for a pair of consecutively-numbered Altec A5's (the real thing) and find that different brands of mylar caps in the simple 2nd-order passive filters. No explanation for this, but its what I found. So they do vary, and don't expect an exact pair-match from vintage equipment.
The new GPA's are more predictable, but it's always a good idea to run your own T/S measurements when you receive a pair of drivers from any vendor.
Why do I put up with this? Because they sound better than most modern prosound equivalents. The alternatives are insanely priced field-coil exotics (which are often hand-made rebuilds of vintage drivers), Lowthers, AER and Feastrex (No!), or weird specialist drivers that have QC issues resulting from the quirky retro style of construction.
The GPA's are real Altecs, at reasonable prices, made by former Altec staff, on the same dies and tooling used in the former Altec repair facility in Oklahoma City. They're Altec all the way through, minus the trademark. They are not reproductions in any sense, since they are made by the same people, with the same tooling, in the same location.
The new GPA's are more predictable, but it's always a good idea to run your own T/S measurements when you receive a pair of drivers from any vendor.
Why do I put up with this? Because they sound better than most modern prosound equivalents. The alternatives are insanely priced field-coil exotics (which are often hand-made rebuilds of vintage drivers), Lowthers, AER and Feastrex (No!), or weird specialist drivers that have QC issues resulting from the quirky retro style of construction.
The GPA's are real Altecs, at reasonable prices, made by former Altec staff, on the same dies and tooling used in the former Altec repair facility in Oklahoma City. They're Altec all the way through, minus the trademark. They are not reproductions in any sense, since they are made by the same people, with the same tooling, in the same location.
Looking at the T/S measurements (and allowing for the 8 and 16-ohm variations in voltage sensitivity), it looks like a pair of side-by-side GPA 414-16B Alnico drivers (in compact closed-box cabinets), combined with a single GPA 416-8B Alnico (in a larger closed-box cabinet with matching width), would offer efficiency in the 99 dB/meter range, along with an improved directivity match to the MF/HF horn.
The nominal 97 dB/meter efficiency of the GPA 416-8B Alnico is increased by proximity to the floor image, so I'd expect a real-world figure between 99 and 100 dB/meter for the bass driver.
That's not a bad setup, and two closed-boxes made of Baltic Birch plywood, one stacked on top of the other, isn't a complicated build, either. The overlap between the drivers could be adjusted with a tapped inductor for the 416-8B Alnico bass driver, so it could be matched to the room location (proximity to the corner). 45 or 30-degree corners on the upper and lower boxes would look nice and improve diffraction from the left and right edges.
I'm of the opinion that VLF in the region between 20~40 Hz has little sensation of tonality, so that's better handled with dedicated, self-powered subwoofers scattered around the room. My experience with the Ariels, which start dropping off around 60 Hz (similar to the closed-box GPA 416-8B Alnico), is that setting the subwoofer crossover any higher than 40 Hz leads to noticeable overlap and murky sound (most noticeable on piano with a bass line). So a one-octave, self-powered subwoofer is a good complement for a 416-8B Alnico driver in a 3.5 to 4.5 cubic foot (100 to 127 liter) box.
Alternatively, the upper box can have a single GPA 515-8C Alnico in it, with similar performance to the paired GPA 414-16B's. Since the Qt of the 515 is substantially lower than the 416 (Qt=0.2 versus Qt=0.27), the box volume can be reduced by about a third, if desired. I'd retain the 45 or 30-degree angled corners, as suggested above.
Since all drivers have similar tonality, the overlap region can be adjusted for best room match, and doesn't need to be an aggressive 3rd or 4th-order filter. I'm not usually a fan of gradual 1st-order filters, but this looks like a good application. All drivers are in their piston band (flat), and the response at the listening position is dominated by room loading (proximity to corner) and room standing waves.
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Sadly, so true
Phooey!
Where is the sport in that? You'll miss out on all the reconing, remagnetizing, magnet replacements, hair pulling, box and port modifying, selling, swapping, etc, etc. This is supposed to be a hobby, isn't it?
Hi there,
Swak, we discussed the petite Onken project about two years ago now. Here on DIYaudio:
http://www.diyaudio.com/forums/multi-way/253853-la-petite-onken.html
At that time, I wasn't even sure to use Altec's 414 or GPA's. Then, I decided GPA for some of the reason discuss above. After that, I remember that GM help me to determine whether to keep the original petite Onken volume or to modify it. Depending on amplifier's damping factor, it looks like the volume could be lower or higher. He suggested me to keep it the same as the original petite Onken (190l) which was an excellent idea. I must admit that this speaker works even better than what I thought of.
Now, the calculation made for the considered enclosure with a GPA 416-8B was made last week by André with GPA's T/S published specs. He also draw a first draft of the enclosure with the same face dimension as the petite Onken. Only the depth is a bit more.
Lynn, your suggestion make me think that you are a true designer! Always with stimulating ideas. This said, I must tell you that I prefer to keep my system without subwoofer and with a classic enclosure. We are, like André said to me today, like on a "Beyond the Altec 19" project
Regarding the idea discuss earlier today also from André about the use of the 414 in the low-mid, if that would be a choice to add a fourth way, I'll choose to move in the Onken range and "get" a pair of Onken 255 driver and 200 Wood low-mid horn or something similar. Anyway, for now I'd like to stay in 3 ways.
Sébastien
Swak, we discussed the petite Onken project about two years ago now. Here on DIYaudio:
http://www.diyaudio.com/forums/multi-way/253853-la-petite-onken.html
At that time, I wasn't even sure to use Altec's 414 or GPA's. Then, I decided GPA for some of the reason discuss above. After that, I remember that GM help me to determine whether to keep the original petite Onken volume or to modify it. Depending on amplifier's damping factor, it looks like the volume could be lower or higher. He suggested me to keep it the same as the original petite Onken (190l) which was an excellent idea. I must admit that this speaker works even better than what I thought of.
Now, the calculation made for the considered enclosure with a GPA 416-8B was made last week by André with GPA's T/S published specs. He also draw a first draft of the enclosure with the same face dimension as the petite Onken. Only the depth is a bit more.
Lynn, your suggestion make me think that you are a true designer! Always with stimulating ideas. This said, I must tell you that I prefer to keep my system without subwoofer and with a classic enclosure. We are, like André said to me today, like on a "Beyond the Altec 19" project
Regarding the idea discuss earlier today also from André about the use of the 414 in the low-mid, if that would be a choice to add a fourth way, I'll choose to move in the Onken range and "get" a pair of Onken 255 driver and 200 Wood low-mid horn or something similar. Anyway, for now I'd like to stay in 3 ways.
Sébastien
Side by side direct radiators in my experience don't control directivety much below where I would cross them. They will be more sensitive and have mutual coupling with up to a 6 db gain. If you are after higher output and lower distortion at the same SPL they can do the trick however compared to bass horn you won't get the super fast attack and transient "pulse" and hair raising realism a good horn delivers. I have used side by side 15's 12's and even circular arrays of big motor light weight 6 inch drivers with the mid high horn centered. In all cases no contest compared to a bass horn. Right now I have a single 8" loaded in 48" deep bass horn and it is all smiles.
A low mass driver with 105 db sensitivity at 100 cycles and virtually flat to 900 cycles at the listening space really gets the juices going.
48 inch long bass horn...best possible mid bass?
Hi Pooh,
I am very interested in your comments and bass / low midrange system.
The fact that you have actually built, tested and compared such a wide variety of direct radiators and horns to cover the bass / low mids makes you one of the very few people genuinely qualified to talk on the subject of how they actually compare for real.....Most commentators form opinions based on simulations and / or non valid comparisons....Your playing field is very level!
I have never built a bass horn as I am focused on commercial applications not a DIY one off system, and the commercial market for bass horns is not my niche.
But I am always seeking the very best reference system to test how close I can get with a commercially acceptable compact system.
Can you share, here on on PM if its off Lynn's main topic, details of the drivers, crossovers, cabinets etc?
Thanks in advance and all the best
Derek.
Hi Pooh,
I am very interested in your comments and bass / low midrange system.
The fact that you have actually built, tested and compared such a wide variety of direct radiators and horns to cover the bass / low mids makes you one of the very few people genuinely qualified to talk on the subject of how they actually compare for real.....Most commentators form opinions based on simulations and / or non valid comparisons....Your playing field is very level!
I have never built a bass horn as I am focused on commercial applications not a DIY one off system, and the commercial market for bass horns is not my niche.
But I am always seeking the very best reference system to test how close I can get with a commercially acceptable compact system.
Can you share, here on on PM if its off Lynn's main topic, details of the drivers, crossovers, cabinets etc?
Thanks in advance and all the best
Derek.
Hi Lynn,
We'll have to see how the Onken 500Wood horn/OS-500MT mid-driver behave and the lower specs. There is also the possibility to use Onken OS-455MT which, if my memories is right, can go a bit lower, but less in the high. I think that Gilles Nicot, a friend on Melaudia's french forum with an full Onken 4 ways system told me last fall that the 455 is best suited for 4 ways design.
Regarding cross-over, it is my intention to keep it as simple as possible. Actually, I'm using a Kaneda's inspired 6dB/oct. on all my ways. It works very well.
About the moving cone (or not), funny to read that. In almost two years using GPA 414-8B, I think that I hardly saw the woofer moving few times.
The overall tonal quality will be for sure one of the main concern while passing to a 414 to a 416. This is to consider. This said, I realized that Kaneda has design many speakers in 3 ways using the Altec 416, Onken OS-500MT mid and Onken OS-5000T tweeter. See here:
ƒIƒ“ƒPƒ“ Web Site
Finally, rumor is true about Kaneda's transistor amplifiers of the last generation, starting with the incredible Kaneda 209. I had in the last year Kaneda's no. 209, 228 and 228+. All of the three are amazing amp. I bought them from Teksanyo (Osaka, Japan):
ƒeƒNƒjƒJƒ‹ƒTƒ“ƒˆ�[�Eƒz�[ƒ€ƒy�[ƒW
Good day to all,
Sébastien
We'll have to see how the Onken 500Wood horn/OS-500MT mid-driver behave and the lower specs. There is also the possibility to use Onken OS-455MT which, if my memories is right, can go a bit lower, but less in the high. I think that Gilles Nicot, a friend on Melaudia's french forum with an full Onken 4 ways system told me last fall that the 455 is best suited for 4 ways design.
Regarding cross-over, it is my intention to keep it as simple as possible. Actually, I'm using a Kaneda's inspired 6dB/oct. on all my ways. It works very well.
About the moving cone (or not), funny to read that. In almost two years using GPA 414-8B, I think that I hardly saw the woofer moving few times.
The overall tonal quality will be for sure one of the main concern while passing to a 414 to a 416. This is to consider. This said, I realized that Kaneda has design many speakers in 3 ways using the Altec 416, Onken OS-500MT mid and Onken OS-5000T tweeter. See here:
ƒIƒ“ƒPƒ“ Web Site
Finally, rumor is true about Kaneda's transistor amplifiers of the last generation, starting with the incredible Kaneda 209. I had in the last year Kaneda's no. 209, 228 and 228+. All of the three are amazing amp. I bought them from Teksanyo (Osaka, Japan):
ƒeƒNƒjƒJƒ‹ƒTƒ“ƒˆ�[�Eƒz�[ƒ€ƒy�[ƒW
Good day to all,
Sébastien
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I always wondered how GPA keeps the cone formula the same as the older Altec's? Do they make their own cones or are they sourced out? And if so are they using the recipe for what was considered to be the best sounding of cones that Altec had over the years for all their GPA products? Just curious as that is where all the sound is coming from etc .