My A7-500s. A journey

**VolvoHeretic** · August 2nd, 2011, 12:38 PM

Dominique, could you tell me the dimensions of your bass port? I suppose it all depends on what drivers you are using and I still haven't wrapped my fingers around all of the Altec parts numbers. My A7-500 bought new in 1976 doesn't show up in any old literature. It is a plywood (3/4" plywood) enclosure with the small removable bass driver rear panel, the horn was installed in the front port, and it looks like your A7, except it has a routered out round cornered cloth covered port panel. It came with the 416-8A woofer, N501-8A crossover, I think 511B horn but since it is now enclosed in a sealed horn box and I can't see the horn driver, I will guess has the 802D compression driver. Make sence?

**stéphane Rame** · August 2nd, 2011, 01:28 PM

Optimisation des ?vents d'une VOT

"J'ai accord? l'enceinte comme un bass reflex, avec un ?vent laminaire de 6 cm de haut, 60 cm de large at 15,5 cm de profondeur (voir mesure d'imp?dance)."

St?phane

**Panomaniac** · August 2nd, 2011, 10:26 PM

"J'ai accord? l'enceinte comme un bass reflex, avec un ?vent laminaire de 6 cm de haut, 60 cm de large at 15,5 cm de profondeur (voir mesure d'imp?dance)."

Yes, looks like Dominique ended up with a BR tuning circa 33Hz

**VolvoHeretic** · August 2nd, 2011, 11:13 PM

Originally Posted by stéphane Rame

Optimisation des ?vents d'une VOT

"J'ai accord? l'enceinte comme un bass reflex, avec un ?vent laminaire de 6 cm de haut, 60 cm de large at 15,5 cm de profondeur (voir mesure d'imp?dance)."

St?phane

Translation please.

**dominique-tanguy** · August 3rd, 2011, 03:32 AM

"I have tuned the port like a bass reflex, with a laminar vent 60 cm wide, 6cm height and 15.5 cm deep (See impedance measurement)".

This adjustment is of course valid for a given loudspeaker, but basic prinicple can be retained and surface as well. You will have to adjust the lenght of the port. You should also avoid very long "tunnel". It seems, for example, that a 416-8A would give a very different setting with a much longer port (and a lower F3).

Kind regards,

Dominique

**voice of the theater** · August 2nd, 2011, 06:42 PM

Originally Posted by VolvoHeretic

Dominique, could you tell me the dimensions of your bass port? I suppose it all depends on what drivers you are using and I still haven't wrapped my fingers around all of the Altec parts numbers. My A7-500 bought new in 1976 doesn't show up in any old literature. It is a plywood (3/4" plywood) enclosure with the small removable bass driver rear panel, the horn was installed in the front port, and it looks like your A7, except it has a routered out round cornered cloth covered port panel. It came with the 416-8A woofer, N501-8A crossover, I think 511B horn but since it is now enclosed in a sealed horn box and I can't see the horn driver, I will guess has the 802D compression driver. Make sence?

I'm surprised it came with the 416-8A. I would have thought if you bought it new in 1976 it would have the 416-8B.....

**Old Guy** · August 2nd, 2011, 07:48 PM

Originally Posted by voice of the theater

I'm surprised it came with the 416-8A. I would have thought if you bought it new in 1976 it would have the 416-8B.....

Old days were different...Dealer might have stock for a long time...would be surprised if the woofers were dated 76. More likely 73-74, shipped to dealer in 75, sold in 76. Things moved slower then...and it wasn't all due to a haze in the air...

**VolvoHeretic** · August 2nd, 2011, 09:00 PM

They must have sat at the dealer for a long time, because when I discovered them I bought them for $400 each. I am wondering if they are 416A's since they are green and have 15" baskets after looking at this site; Altec
They have no markings on them whatsoever(edit; AL58), I will have to drag out a horn and see what they have to say? One woofer is blown, do I have to send in both to be reconed and magnitized? The one that still works has a shredded cap from when I was running them full blast and heard a strange noise comeing out of it and discovered the cat up in the bass horn clawing the crap out of it. I wonder if he went deaf?

**dominique-tanguy** · August 3rd, 2011, 03:37 AM

Originally Posted by VolvoHeretic

Dominique, could you tell me the dimensions of your bass port? I suppose it all depends on what drivers you are using and I still haven't wrapped my fingers around all of the Altec parts numbers. My A7-500 bought new in 1976 doesn't show up in any old literature. It is a plywood (3/4" plywood) enclosure with the small removable bass driver rear panel, the horn was installed in the front port, and it looks like your A7, except it has a routered out round cornered cloth covered port panel. It came with the 416-8A woofer, N501-8A crossover, I think 511B horn but since it is now enclosed in a sealed horn box and I can't see the horn driver, I will guess has the 802D compression driver. Make sence?

Dear Volvoheretic,
I strongly recommend that you try the "serie" Xover I mentionned before. Very easy to build and could improve a lot your system...
Regards,
Dominique

**Panomaniac** · August 3rd, 2011, 02:45 PM

Dominique. I"m going to have to try the hanging felt curtain trick. I can't remember if we used in in Hiraga's A5, but it was common in a lot of is other work. You seem to have gotten such good results it's worth try.

With my strange 0.44 Qts 416-8As, your 33Hz box tuning may give a 5dB hump at the bottom end. That could actually be a big help with my rig.