Altec on Open Baffles

[rajagopal_j]

Hello from India,

I have been reading and following many threads on this forum for well more than 2 years now, I have read and learnt a lot here.

The following is my Altec Rig setup with lots of inputs from this forum.

Couple of interesting points about my setup
- I use the JE Labs Open Baffle. The baffles are homemade and yet to be finished.
- I bi-amp with a GM70 SET amp for LF and 2A3 SET amp for HF
- The GM70 Amplifier was originally an integrated bought from Lyrita Audio which has been modified and the pre and power stages separated
- I use LeCleach Horns made by a friend out of solid teak wood (Same person who designed and built my amplifiers for me Lyrita Audio)
- I use solid core wire for the LF and 2 strands of Cat5 (ethernet cable) for the HF



Source: Logitech Squeezebox Touch, Dual 1229, Technics SL D3, NAD CD 512, Tandberg TCD440a, Nakamichi 582
-> Lyrita Audio GM70 SET - Pre Stage -> SAE 4000 Crossover (HF rolls off at 1Khz and LF comes up to 1.2KHz)
SAE LF Out -> GM70 Output Stage (15wpc) -> Altec 416 (8ohms GPA recone kit)
SAE HF Out -> Lyrita 2A3 SET 2 Channel Power Amp (1.5 wpc) -> Altec 288K (8ohms GPA Diaphragms)

Hoping to interact more and get inputs here!

[Phil-G]

wow, i like the teak horns. and the speaker basket table adds a nice touch. i'd like to see more pictures of the open baffles.

[GM]

Greets!

Nice! A pity you can't get even acoustical loading due to the open area to the right. Maybe make a free standing false wall partition? I'm curious, I can't see any vent screens in the 416's dust caps. Curious too why a 288 to only go down to ~1.2 kHz. Love those teak horns though!

GM

[rajagopal_j]

wow, i like the teak horns. and the speaker basket table adds a nice touch. i'd like to see more pictures of the open baffles.

There is only so much to the open baffle , its just a single sheet of plywood with 2 stands to the sides.



The speaker stand and books are temporary, I am at the moment designing a system to hold up the HF Driver. Open Baffles don't have the luxury of a box top for easy placement of the driver. Should have the solution fabricated hopefully by end of this month.

Thats not a speaker basket table, but drivers I have in my collection . I just happened to keep the my record stabilizing ring and a few books on top of it when I took the picture.



Altec 416 to be reconed, Klangfilm KL L405 to be reconed (looks impossible as kits are not available any good leads here would be appreciated), Goodmans Audiom P-15 with original paper but the surrounds have formed holes with time need to get that fixed.

Greets!

Nice! A pity you can't get even acoustical loading due to the open area to the right. Maybe make a free standing false wall partition? I'm curious, I can't see any vent screens in the 416's dust caps. Curious too why a 288 to only go down to ~1.2 kHz. Love those teak horns though!

GM

GM There is a french window on the right side, I had them open in the previous shot for some light. These two pictures should give some perspective. The curtains are fairly thick and the windows have rubber beadings on the them to ensure they dont rattle. There is even loading with this. The imaging and resolution are spot on with the Chesky test disks.



The vents on the dust cap.

I tried as low as 800Hz, but somehow I liked the HF going down to 1 Khz only. The LF goes up to 1.2 Khz. Thats seemed to be the sweet spot for me. That being said, the SAE 4000 values might be off due to age, I guess I need to procure measurement gear and measure the actual roll/cut offs for the drivers.

[GM]

GM There is a french window on the right side...........The imaging and resolution are spot on with the Chesky test disks.

The vents on the dust cap.

I tried as low as 800Hz, but somehow I liked the HF going down to 1 Khz only.

Ah! Cool!

Hmm, the weave looks almost like a crude plastic molding to me, though have yet to see a GPA re-cone. What does it look like to you? I mean all the Altecs I've seen have a fine metal mesh.

Yeah, it's a small horn, so isn't going to go low. I was curious why you're using 288s for wide BW tweeter horns, when a small format 1" driver would be more appropriate.

GM

[rajagopal_j]

Hmm, the weave looks almost like a crude plastic molding to me, though have yet to see a GPA re-cone. What does it look like to you? I mean all the Altecs I've seen have a fine metal mesh.

I am not sure what material it is, it is soft to the touch, bends with very slight pressure and is quite springy could be plastic or cloth, most probably plastic. It is definitely not a mould, it is finely woven but not metal.

Yeah, it's a small horn, so isn't going to go low. I was curious why you're using 288s for wide BW tweeter horns, when a small format 1" driver would be more appropriate.

GM

Probably the images are making it look real small, it is a Le'Cleach Horn with a 600Hz cut off. I am in the process of making one with 450 Hz cut off out of fiber glass, similar to the Azura Horn. That should make a huge difference to the presentation and soundstage. Hoping that it should also help the 288 go down to 800Hz.

I do have a pair of 808-8Bs and 908-8Bs, should plan something with them soon along with either the Klangfilm or Goodmans.

[GM]

OK, then small to me and for a 288, considering its suitable down to 300 Hz on a large enough horn.

GM

[Altec Best]

IMHO if your going to use a big 288 you definitely need to box up the woofers..Those 288's will over power a single woofer in a hurry.With open baffles being already bass shy IMO..You might want to add another pair of woofers into that setup..Love the horns too !

[rajagopal_j]

IMHO if your going to use a big 288 you definitely need to box up the woofers..Those 288's will over power a single woofer in a hurry.With open baffles being already bass shy IMO..You might want to add another pair of woofers into that setup..Love the horns too !

you would be surprised at the amount of bass that comes from the OBs I have had to attenuate the HF only by 8db. A friend here in Chennai has the 288g and 416 in a half horn box design and he attenuate s by about 12 db. That being said I am planning a western electric sub woofer design for either the goodmans or the second pair or altec 416s I have .