Always seeking to go forward, I found the excellent M.J.King work on back loaded horns. and plugged in the T/S from a Dayton 305-8. I came up with a rear firing folded horn of 3 elements with a length of 6.2 feet. I had to increase box width to 24". This allowed a cut off of 70Hz. With it near a cement wall and on a tile floor, in an 18x24x9 room, it may give me more around 40Hz than the BR design I came up with last time.
If I cross at 500Hz and reverse the connections to the 808's, the phasing with the front of the 412 seems to work. I have no idea how the phasing of the rear firing mouth will work with the forward firing elements, however.
Not in a huge hurry to start cutting wood, so I can modify what I have here if I get the actual T/S data from the 412 and it turns out to be significantly different.
Thanks for checking Pano,
If I cross at 500Hz and reverse the connections to the 808's, the phasing with the front of the 412 seems to work. I have no idea how the phasing of the rear firing mouth will work with the forward firing elements, however.
Not in a huge hurry to start cutting wood, so I can modify what I have here if I get the actual T/S data from the 412 and it turns out to be significantly different.
Thanks for checking Pano,
Oh, as I'm new to horn design, would a 2.3 cu' chamber between back of driver and throat be sufficient? Fs=30 effective piston I'm figuring at 391.1cm2 with xmax of 8mm. As I'm plugging the xmax in from another speaker (Dayton 305-8), precision is a lot to expect. I may be small on the effective piston, as I measured actual cone dia. without the surround, which the accordion pleated cloth type, an may contribute.
just puzzled
anyone can say from first hand experience , in simple words - sound difference between 755 and (any iteration of ) 409 ?
I know physical difference and had pleasure to see 755 and briefly hear them on last year's BAF ....
anyone can say from first hand experience , in simple words - sound difference between 755 and (any iteration of ) 409 ?
I know physical difference and had pleasure to see 755 and briefly hear them on last year's BAF ....
Watching NASCAR, golf, hockey, basketball, etc., not to mention the nice weather in my locale......😉
Anyway, having owned both, but not at the same time, it's an apples n' oranges comparison to me with the 755 a smooth 'talker' and the best overall sounding wide range 8" I've ever auditioned, though admitted I haven't been exposed to a very wide variety. The 409 seemed best suited for a small short horn cab similar to an 825, so that's what I built.
GM
Anyway, having owned both, but not at the same time, it's an apples n' oranges comparison to me with the 755 a smooth 'talker' and the best overall sounding wide range 8" I've ever auditioned, though admitted I haven't been exposed to a very wide variety. The 409 seemed best suited for a small short horn cab similar to an 825, so that's what I built.
GM
409A is OK, not great in any way. Lacks 755As definition and HF extension.
409B is a coax with 2k crossover...never heard this one.
No other Altec 8" is even close to the 755A in wide range performance and basic quality, not even the other 755 versions.
There is no substitute for a 755A.
Mid 50s 408A Biflex is probably second best. Good bass but soft and rolled off, not crisp, super fast, and extended like a 755A
409B is a coax with 2k crossover...never heard this one.
No other Altec 8" is even close to the 755A in wide range performance and basic quality, not even the other 755 versions.
There is no substitute for a 755A.
Mid 50s 408A Biflex is probably second best. Good bass but soft and rolled off, not crisp, super fast, and extended like a 755A
Hello,
I have a active biamped Altec system and would like to incorporate an active sub.
What are some good crossover point for an active subwoofer to an Altec 828/515-8c?
Tx.
I have a active biamped Altec system and would like to incorporate an active sub.
What are some good crossover point for an active subwoofer to an Altec 828/515-8c?
Tx.
Right. It depends on how you have ported the 828. I'd say 50Hz as a first try if you've closed up the ports a bit. Higher if you have the very large, stock ports.
OK, 'll try to calc from that, but the 828 box is hard (for me) to simulate. Do you have any way of measuring?
Hi Pano - sorry, don't have an analyser. One of the local carpenters build the 828s for me. Appreciate your assistance - Tx.
I went out an got a 15" Rythmik sub and crossover at 50Hz. the sub has some EQ funtions that I am tweeking for my set-up.
Measuring the Altec 828 Box
Are you looking for measurements of the 828 box? I have a stock pair.
I posted measurements here, midway down the page. Altec VOTT Reborn!!
Since that time I have swapped out the JBL 2446 compression driver on the IWATA horns for Beyma CP-750Ti CDs. Wow! What an improvement!! The harshness at 8kHz that I describe is no longer there and frequency response is pretty much flat out to 18kHz.
Are you looking for measurements of the 828 box? I have a stock pair.
I posted measurements here, midway down the page. Altec VOTT Reborn!!
Since that time I have swapped out the JBL 2446 compression driver on the IWATA horns for Beyma CP-750Ti CDs. Wow! What an improvement!! The harshness at 8kHz that I describe is no longer there and frequency response is pretty much flat out to 18kHz.
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