Hi Guys,
I originally want to buy a pair of woofer, but bought a pair of 418B without checking the specification of the speakers.
I still wish to make use of them, if possible as a woofer, if not please advise what configuration will be best for this speakers.
Thanks in advance
Albert
I originally want to buy a pair of woofer, but bought a pair of 418B without checking the specification of the speakers.
I still wish to make use of them, if possible as a woofer, if not please advise what configuration will be best for this speakers.
Thanks in advance
Albert
Greets!
It's a musical instrument driver best suited for a lead guitar amp or similar, so has a ~45 Hz Fs, ~0.3 Qts, high Vas (~250 L?) and very small Xmax (1.3 mm) IIRC: http://www.lansingheritage.org/images/altec/catalogs/1972-mi/page04.jpg
It has high efficiency, so if you drive it with a high output impedance amp it should play down into the 30s at modest SPL if the box is big enough and tuned low enough. Coupled to an Altec 811 horn and 1200-1500 Hz XO it will make a nice mini-M19: http://www.lansingheritage.org/html/altec/specs/home-speakers/model-19.htm
GM
It's a musical instrument driver best suited for a lead guitar amp or similar, so has a ~45 Hz Fs, ~0.3 Qts, high Vas (~250 L?) and very small Xmax (1.3 mm) IIRC: http://www.lansingheritage.org/images/altec/catalogs/1972-mi/page04.jpg
It has high efficiency, so if you drive it with a high output impedance amp it should play down into the 30s at modest SPL if the box is big enough and tuned low enough. Coupled to an Altec 811 horn and 1200-1500 Hz XO it will make a nice mini-M19: http://www.lansingheritage.org/html/altec/specs/home-speakers/model-19.htm
GM
GM,
Thanks a bunch and nice to have you along.
According to the catalog, it seems to me the dimension including the 811 horn at the top. Would you be kind enough to show me the box dimension for the 418B as well since I'm a old newbie and a copy cat to be exact.
Albert
Thanks a bunch and nice to have you along.
According to the catalog, it seems to me the dimension including the 811 horn at the top. Would you be kind enough to show me the box dimension for the 418B as well since I'm a old newbie and a copy cat to be exact.
Albert
I use a pair of these in some monstrous Karlson enclosures . . . I only use them for the sub-120 hz material, as I have some DIY open baffle line arryas for the rest of the music spectrum.
they are SUPER efficient, and have some serious snap (and thump for that matter)
I don't like using them much higher than 150 - 200 Hz as I think they get kinda honky (they are MI speakers after all . . .)
I've never actually measured their frequency response in the Karlsons, but they seem to drop like a rock around their Fs . . .not a big deal for me really . . .
They like lotsa clean SS power, but I have used them with little tube amps too . . . best sound to date from them came from a BIG pro audio mixer putting out 400 watts RMS per channel . . . . ridiculous SPL levels . . . and great midbass snap in the Karlsons . . .
these Altec's really like to be spanked ! I ran the amp so it was just under the clipping threshold for about 5 hours at a DJ gig, and they could've played for DAYS at that level with no sweat.
good luck and have fun 😉
they are SUPER efficient, and have some serious snap (and thump for that matter)
I don't like using them much higher than 150 - 200 Hz as I think they get kinda honky (they are MI speakers after all . . .)
I've never actually measured their frequency response in the Karlsons, but they seem to drop like a rock around their Fs . . .not a big deal for me really . . .
They like lotsa clean SS power, but I have used them with little tube amps too . . . best sound to date from them came from a BIG pro audio mixer putting out 400 watts RMS per channel . . . . ridiculous SPL levels . . . and great midbass snap in the Karlsons . . .
these Altec's really like to be spanked ! I ran the amp so it was just under the clipping threshold for about 5 hours at a DJ gig, and they could've played for DAYS at that level with no sweat.
good luck and have fun 😉
albertli said:
You're welcome!
OK, so you're saying you want to make a mini-M19 complete with 811 horn system or just a woofer cab or.......?
Regardless, I'll need your amp's output impedance (not their tap ratings) or at least their damping factors (DF) to ensure the cab is large enough to keep its bass line from sounding too 'warm'/'bloated'/'loose'. Otherwise, all I can do is assume a 'worst case' size tuned to Fs and you may have to reduce its internal size and re-tune the vent.
Also, any width/depth height preferences/limitations?
GM
albertli said:
that should sound very nice . . . what are the output transformers on the two amps ?
GM, & bottom feeder.
The output transformer on my 2A3 are 2.5K double C core with 8R secondary and the EL84PP with a pair of Edcor 7.6K primary and 8R secondary.
GM, I personally love to make it a bass only speaker, so I could play around with different combination.
Albert
The output transformer on my 2A3 are 2.5K double C core with 8R secondary and the EL84PP with a pair of Edcor 7.6K primary and 8R secondary.
GM, I personally love to make it a bass only speaker, so I could play around with different combination.
Albert
GM,
I thought I didn't answer your questions, but I don't know what are the damping factors of two of my amps. The EL84pp is ' The Bovois Vally' designed by Morgan Jones. A friend of mind gave me the schematic, but without any description.
Size of the box is not too critical.
Regards
Albert
I thought I didn't answer your questions, but I don't know what are the damping factors of two of my amps. The EL84pp is ' The Bovois Vally' designed by Morgan Jones. A friend of mind gave me the schematic, but without any description.
Size of the box is not too critical.
Regards
Albert
Greets!
No, not really. The PP is probably around 0.8-1.4 ohms, so not much, but I assume the 2A3 is a SET, so will be somewhat higher. Anyway, with no driver, amp measured specs, a 'worst case' alignment would be over 20 ft^3 tuned to around 32 Hz, a bit much for a 12". It could be severely under-damped with the PP amp, so choosing a compromise of ~10 ft^3 net/32 Hz seems the way to go with the PP amp making it an EBS alignment (my preference) with the SET being a somewhat 'fuller' sound, though still 'tight'. If it turns out to be a ~matching impedance amp (DF= ~1), then it becomes a classic Altec 'West Coast Sound' alignment that can be 'tightened up' by adding vent damping if desired and ~critically damped if blocked off.
So, is a pair of 42" H x 35" W x 14.25" D cabs too big?
GM
No, not really. The PP is probably around 0.8-1.4 ohms, so not much, but I assume the 2A3 is a SET, so will be somewhat higher. Anyway, with no driver, amp measured specs, a 'worst case' alignment would be over 20 ft^3 tuned to around 32 Hz, a bit much for a 12". It could be severely under-damped with the PP amp, so choosing a compromise of ~10 ft^3 net/32 Hz seems the way to go with the PP amp making it an EBS alignment (my preference) with the SET being a somewhat 'fuller' sound, though still 'tight'. If it turns out to be a ~matching impedance amp (DF= ~1), then it becomes a classic Altec 'West Coast Sound' alignment that can be 'tightened up' by adding vent damping if desired and ~critically damped if blocked off.
So, is a pair of 42" H x 35" W x 14.25" D cabs too big?
GM
GM,
Thanks so much
The 418B is 15" and I would like to have the box a bit narrower and deeper if possible
Albert
Thanks so much
The 418B is 15" and I would like to have the box a bit narrower and deeper if possible
Albert
Oops! Senior Moment, I took a break from doing a 12" design to post yours. Apparently I can't do two things at once anymore. 🙁
OK, how about 42" H x 27.75" W x 17.75" D?
GM
OK, how about 42" H x 27.75" W x 17.75" D?
GM
I got a better idea, you tell me what size you want and I'll suggest a porting to experiment with.
GM
GM
OK, then using 0.75" (19 mm) thick material (preferably 11-13 ply Baltic Birch or Apple plywood) this equates to ~6.693938 ft^3/189.551 L gross or ~6.4 ft^3/181.228 L net which relegates it to a mid-bass alignment with a much rolled off bass unless tuned to Fs with a very high output impedance that will result in a bloated mid-bass.
All this assumes of course that its specs are ~what I'm assuming, i.e. very similar to Altec's other 15" MI/prosound drivers of the day that I have measured specs for. I thought I had some for the 418B also, but can't find them.
Also, due to the L:W:H ratio being well below an optimum golden or acoustic one, more damping is typically required if a high XO point is used which can cause the woofer's HF to sound somewhat 'muffled', making for an audible tonal shift through the XO BW.
Anyway, classic tuning to equal impedance peaks based on a 44.8 Hz Fs with the driver at extreme top, vent centered at 25.5"/64.77 cm down, so some experimentation will be required to center it to the actual Fs for best LF performance:
8" diameter (~50.266"^2/324.293 cm^2) x baffle thickness long with a longer vent tuning it lower if desired. 1 W, half space sim with a SET's typical 2.5 ohms of series resistance below.
Of course a removable (gasketed) vent panel is required if you can't find a suitable, easy to cut pipe or square or rectangular duct to experiment with.
Please let us know what tuning, damping, room location, HF section you wind up with and of course your impressions of its performance.
GM
All this assumes of course that its specs are ~what I'm assuming, i.e. very similar to Altec's other 15" MI/prosound drivers of the day that I have measured specs for. I thought I had some for the 418B also, but can't find them.
Also, due to the L:W:H ratio being well below an optimum golden or acoustic one, more damping is typically required if a high XO point is used which can cause the woofer's HF to sound somewhat 'muffled', making for an audible tonal shift through the XO BW.
Anyway, classic tuning to equal impedance peaks based on a 44.8 Hz Fs with the driver at extreme top, vent centered at 25.5"/64.77 cm down, so some experimentation will be required to center it to the actual Fs for best LF performance:
8" diameter (~50.266"^2/324.293 cm^2) x baffle thickness long with a longer vent tuning it lower if desired. 1 W, half space sim with a SET's typical 2.5 ohms of series resistance below.
Of course a removable (gasketed) vent panel is required if you can't find a suitable, easy to cut pipe or square or rectangular duct to experiment with.
Please let us know what tuning, damping, room location, HF section you wind up with and of course your impressions of its performance.
GM
Attachments
GM,
Thanks so much for your precious time. I thought I need lot of time to digest, then I know how to ask questions.
Eh...... I can sense that the size I provide is beyond the golden ratio and or acoustic ratio. If so, I'd rather stick with 42"H x 27.75"W x 17.75D to have better performance.
Is the vent the same size 8" x ? Please kindly give details.
Albert
Thanks so much for your precious time. I thought I need lot of time to digest, then I know how to ask questions.
Eh...... I can sense that the size I provide is beyond the golden ratio and or acoustic ratio. If so, I'd rather stick with 42"H x 27.75"W x 17.75D to have better performance.
Is the vent the same size 8" x ? Please kindly give details.
Albert