driver advice for 2360 horns on Altec A7/828s

[kip.duff]

What is your need for the extra efficiency. That isn't necessarily the key to good sound. The 515-8G is a more efficient driver than the others but it at the cost of cone mass (take a feel of the 515-G compared to any other 515 driver. The 515-G, while more efficient, isn't as good as the GPA 515-LF, in my opinion, in terms of frequency response and power handling and overall sound. I'd give up the 1dB of efficiency in a heartbeat.

You are speaking about 515-G which I believe is a circa 1994 Altec Lansing ferrite version in the 515 line. I have not mentioned this model as one of the models I was considering using- but that could change. At this point, it's not clear to me why you brought this model up. The 515 types I'm considering are the GPA 515-LF and GPA 515C. I see now that I had wrong info in my previous post- when I wrote "515B", I meant GPA 515C ("Classic")- my apologies. So, the two LF drivers that came to mind for my A7/828s are GPA 515-LF and GPA 515C.



"need for extra efficiency". About 2 years ago, I got a set of drivers that were originally belonging to some 1966 A7/825s: 416A LFs, N-500-E Xovers, 511B horns, and 802D HF drivers. The Xovers were not working, so I repaired them with some MBGO Russian caps- otherwise original. I bought a pair of 828s to install the components into. The 416As were pretty tore up, and rather than getting them reconned, I bought some 416-16Bs from GPA. The porting is original 828 spec- 205 sq in (I think)- not the more popular 90 sq in. Frequency response curves I generated showed overall same efficiency for the two port configurations- with some difference in the tow, of course.

This setup has always been aggressive in the high end- I believe for more than one reason. And HF attenuation knob on the Xovers almost always at max attenuation position. With the JBL 2446/2360 or JBL 2446/2397 horn setups I am substituting, I believe the SPL gap between LF drivers and HF drivers will even widen. In any event, I would prefer my A7s not to need any attenuation- and I had assumed that's possible. This is based on an uneducated hunch that the horns will sound better without a resistor in series. That's why I want more efficient LF drivers. I already know I'm a dumbass, and that some (many?) people may believe my hunch is silly.

This has been a long-winded way of asking: do you believe the GPA 515-LF or GPA 515Cs are appropriate drivers for my A7/828s? Other LF drivers I should consider? TAD? Also, FWIW, I've noticed that in original LF driver specs, 416As and 515s types are designated for 825/828 box use.

Thanks.......

[kip.duff]

Hi,
I compared the 515-16G with 416-16 and despite several trials and combinations I always preferred the 416-16 but I do not know more for the other versions of the 515, regarding the efficiency I simply doubled the boxes and an adjustment on my DSP XTA and voila.



Currently I'm looking for an amp to power the 416 because my PP2A3 lack a little juice for my rockier days. About the 2360 that I also owned for a while, I liked it but I much prefer the 2397 for the listening room that I have, with 2360 you have to be much further to appreciate, which is why they were designed so in a very large listening room the 2360 would be at their best. With the 2397 the image is better and they disappear, I like.
Keep going, you're on a good track.

Thanks so much for your response. Really getting at the heart of my situation. I was teetering on the brink of getting some 2360s, but I am a little more hesitant now, considering my small space. I almost got a set of local 2397s yesterday, but they were pretty beat. 2397s will be my priority. I have some 2446s with original Ti frams and will get Aquaplas or Truextent.

I have assumed that because my A7s are efficient, that my 300B SET monoblocs are adequate. I think I'm gonna abandon that theory and get something like ANK Interstage 300B parallel monoblocs. Not sure- I listen sometimes at loud levels.

I am gonna research your mention of DSP XTA and PP2A3. Are the drivers for the 2397s in your photo attenuated?

[macsic]

Thanks so much for your response. Really getting at the heart of my situation. I was teetering on the brink of getting some 2360s, but I am a little more hesitant now, considering my small space. I almost got a set of local 2397s yesterday, but they were pretty beat. 2397s will be my priority. I have some 2446s with original Ti frams and will get Aquaplas or Truextent.

I have assumed that because my A7s are efficient, that my 300B SET monoblocs are adequate. I think I'm gonna abandon that theory and get something like ANK Interstage 300B parallel monoblocs. Not sure- I listen sometimes at loud levels.

I am gonna research your mention of DSP XTA and PP2A3. Are the drivers for the 2397s in your photo attenuated?

Hello,
There are 300B and 300B ... I have different and they sound different and I use them for mid and high now, depending on the style and level of the 300B can do the trick. A Push & Pull 2A3 is also very good for mid, it's all a question of tastes and needs. For the vast majority of the time a PP 2A3 (do not research it is a DIY) is sufficient on the 416 but I am still looking for the perfect wedding amp for these, I will surely try soon McIntosh, or KT88 or 845 as soon as I get them.
On my 825 or 828 I calibrated the port and I also arrived at around 200po².
On my XTA DP448 I applied a -6db on my 2450J / 2397 for the moment and it's ok but the final is not decided since I will surely change amps soon and the gain on these influences this choice. I cut at 800 on the lowpass and 7,200 on the highpass with the 2397, as you know you can cut lower with the 2360.

"I already know I'm a dumbass, and that some (many?) People may believe my hunch is silly."

If you are crazy then you are not the only one ;-)

[sguttag]

You are speaking about 515-G which I believe is a circa 1994 Altec Lansing ferrite version in the 515 line. I have not mentioned this model as one of the models I was considering using- but that could change. At this point, it's not clear to me why you brought this model up.

I brought it up because you seemed interested in efficiency. The 515G was designed and built to be the most efficient Altec driver. Check it out in the various cabinets (GPA still produces this driver in both HP and conventional forms...or they did the last time I checked). It uses aluminum v.c. wire and a really lightweight cone.

If you are trying to balance out HF to LF then fix it in the crossover, not by driver efficiency. Let the speaker's performance dictate the driver(s). If it were me, I would Bi-amp it and be done with the worry over sensitivity differences. But that is me. I'm not into the passive crossovers like others (no knock against them as I think of passive crossovers as an art form...it just isn't something that I delve into much...I've been using active crossovers for decades now).

I can say, for any future projects where I would be using a classic Altec horn cabinet (210, 211, 825, 828, 816), the GPA 515 LF is going to be my first pick...not to the exclusion of the other models just that it is my first choice.

[kip.duff]

Based on a talk I had with Bill at GPA and input from this thread, I've decided to address something I should have addressed a while back: crossover. I'm going to raise the crossover from 500 to 800Hz. The treble with my new turntable setup is even more aggressive than it was. Must be dealt with.

I've seen a lot of talk about Hiraga, but I believe it's 600Hz. Is there a decent stock JBL crossover for this application that can get me going till I scratch build one? I don't think I'm prepared to go bi-amp- but I don't know. Actually, REALLY don't know! I get that you use two stereo amps. But is there still a crossover in front of the amps? Using equipment like Pioneer SF-700?

Thanks......

[sguttag]

Yep, you us an active crossover before the amplifiers (two stereo, one 4-channel, 4 monos...whatever works for you). You can DYI the crossover if you want (a simple L-R 24 isn't too hard to build out of common parts) or go DSP with something like miniDSP (were they have both standard and HD grades) or some other brand of active crossover, analog or digital.

[Earl K]

Here's where you can get some Aquaplased diaphragms ( currently on sale for $80.00 > which is a great price ) .

JBL D8R2450SL diaphragm from Speaker Exchange

[Earl K]

Here's a good thread ( from Barry ) on how to EQ your 2360/2446/2450 horn-driver combo ( for a nice flat, listenable response ).

JBL 2360, Getting it Flat

[Earl K]

Here's another thread ( from Jerv ) about EQing the 2445 on a 2360.

Note; the 2445 has a couple of db less midrange output than the newer 2446/2450 type driver ( therefore Jerv's EQ advice is specific to the 2445 ).

[Earl K]

Good Stuff here ( from our German + Norwegian members Gibber + oks81 & many others ) about their 2360 experiences ( using various drivers ) .

[kip.duff]

Here's where you can get some Aquaplased diaphragms ( currently on sale for $80.00 > which is a great price ) .

JBL D8R2450SL diaphragm from Speaker Exchange

Thanks for tip! but I need 16 ohm.....

[kip.duff]

Hi,
I compared the 515-16G with 416-16 and despite several trials and combinations I always preferred the 416-16 but I do not know more for the other versions of the 515, regarding the efficiency I simply doubled the boxes and an adjustment on my DSP XTA and voila.



Currently I'm looking for an amp to power the 416 because my PP2A3 lack a little juice for my rockier days. About the 2360 that I also owned for a while, I liked it but I much prefer the 2397 for the listening room that I have, with 2360 you have to be much further to appreciate, which is why they were designed so in a very large listening room the 2360 would be at their best. With the 2397 the image is better and they disappear, I like.
Keep going, you're on a good track.

Whoa. Thanks to you and sguttag, I've been starting to scratch the surface of the DSP thing. A small door opening to a room with 100 doors kinda thing. Just been looking at MiniDSP products- WTF. How can I buy something that's inexpensive and small? Brings to mind my Sonos Play 5 iPhone streamer- which I am very impressed with. These products are something I'm gonna get involved with- but for now, may probably get conventional crossover box just to get into a 800Hz setup.

Are your horns the Tony Kahn replicas?
And you're not using the 2328 throats?
Does your XTA have RCA connectivity?

[kip.duff]

Yep, you us an active crossover before the amplifiers (two stereo, one 4-channel, 4 monos...whatever works for you). You can DYI the crossover if you want (a simple L-R 24 isn't too hard to build out of common parts) or go DSP with something like miniDSP (were they have both standard and HD grades) or some other brand of active crossover, analog or digital.

WOW. Just been looking at internet stuff on MiniDSP and XTA. Blowing my mind- bit of a learning curve but it looks exciting and worth getting into- and I plan to. Looks like similar technologies used in the Sonos Play 5 iPhone streamer I just bought and really like. One downside is need for extra cables. I have an Audio Research Classic 30 power amp I could use for LF.

I still want a traditional 800Hz xover for immediate future. Looking at a pair of JBL LX13 16 Ohm xovers- do you know if these would be decent, compatible?

[JeffW]

Thanks for tip! but I need 16 ohm.....

They have them, but they are a bit more expensive

https://reconingspeakers.com/product...1sl-diaphragm/

[kip.duff]

They have them, but they are a bit more expensive

https://reconingspeakers.com/product...1sl-diaphragm/

Right- saw em $125. Teetering on them or coughing up $1700 for Truextent. Before I buy any fram, I wanna get horns so I can hear the originals Ti for comparison. Hunting for JBL 2397s and 2328 throats as I write.