Raising the While Flag on 604 Project

[Seadweller]

Photos, lots of photos, please

Here's a sampling...Hope it works...

[Panomaniac]

Thanks, great photos. Very pretty.

I have to say, the box looks too small to me. Maybe that's why you're struggling with not enough bass - too much mid?

Can you post the inside dimensions? There are a number of skilled box guys here, perhaps they can help. And the port size and length is important.

edit:
Hmmm.. looking again a doing a rough estimate, the boxes are not small. Maybe 42Hx24Wx21D.

[Seadweller]

Can you post the inside dimensions? There are a number of skilled box guys here, perhaps they can help. And the port size and length is important.

edit:
Hmmm.. looking again a doing a rough estimate, the boxes are not small. Maybe 42Hx24Wx21D.

The internal cabinet dimensions are 23.125"W x 18.4775"D x 42.5"H. The CSA is 426.3672. Internal volume is 10.486 cubic feet.

Port size is 6". The one thing I have not experimented with is port length. The port insert I have will allow a 3/4" to 6" port length (I'd have to trim it in increments).

The port fires downward, and is 10" from the floor.

edit: By the way, it's an MLTL design.

[Seadweller]

And a few more...The press-fit grills are a work of art...

[GM]

Thanks GM.

........or even more likely, that the excessive midrange energy is masking it.

Honestly, if worse comes to worse, I could add a subwoofer to the system..........

........there is a range of frequencies that when a voice or instrument fall in that range, the beaming is like the phaser on the Enterprise.

Actually, for my own curiosity, would a passive radiator mounted in the bottom of the cabinet be an option? Or how about an active driver?

You're welcome!

Which can be caused by a leaky cab rolling off all the bass.........

Well, I'm not there and for sure if there's a hump in the horn's response it can sure sound this way, but I find it hard to believe that this would occur with JM's XO assuming it has the adjustable pots to dial it in.

PRs have a compliance measured in the hundreds of liters, so they can only be vertically oriented, same as most Altec drivers, including the 416.

Adding a driver to a given cab effectively reduces the air mass spring each driver feels, so F3 goes up and Fb normally must go down to keep it from sounding 'boomy'. In short, it will have ~ a half octave less bass response.

GM

[Seadweller]

You're welcome!

Which can be caused by a leaky cab rolling off all the bass.........

GM

The only possible leaks would be at the removable XO panel on the back of the speaker, or the driver itself...I do not have a gasket behind the driver, although I've seen cork gasket sets on eBay...

The driver and XO panel fit extremely tight to the cabinet, and the XO panel is actually secured by 10 screws...Could a very minute amount of leakage in these areas impact bass response to this degree?

[GM]

Are you saying there's no sealant between the driver or XO and mounting surface? If so, I'd be very surprised if there's no leaks and based on your various observations WRT vent lengths, various XO woes, etc., it would explain them all except maybe some portion of the high intensity beaming which can be dealt with by adding a foam insert, but that comes under the heading of fine tuning.

AFA how big a leak it takes to basically delete the vast majority of box loading it's as little as air leakage around the mounting bolts and T-nut threads, but an air leak around the driver ~completely negates any box loading.

GM

[Art J.]

Hi gang. In my absence, I had to catch up on 11 pages of this subject.
The last time I saw a project go this bad, the problem ended up being the CD player.
Didn't you say it's 20 years old? Is it your only source?
I've heard them shout when they fall out of specs.

[Seadweller]

Hi gang. In my absence, I had to catch up on 11 pages of this subject.
The last time I saw a project go this bad, the problem ended up being the CD player.
Didn't you say it's 20 years old? Is it your only source?
I've heard them shout when they fall out of specs.

Funny you mention this, as it is my only source...This was on my list of suspects, but quite frankly, I never tried another source, because every time I inquired, folks said that it would not be possible for the CD player, being digital, to impart its own sound...

[Seadweller]

Are you saying there's no sealant between the driver or XO and mounting surface?

AFA how big a leak it takes to basically delete the vast majority of box loading it's as little as air leakage around the mounting bolts and T-nut threads, but an air leak around the driver ~completely negates any box loading.

GM

Thanks GM....No, there is no sealant around the XO panel or the driver....The XO panel and cabinet mating surface were milled so they basically seal, but I guess without a gasket of some sort, it would not be completely air-tight....I'm sure there's leakage around the driver as well, but it never occured to me that such a minimal amount of leakage could impact the loading of the cabinet to this degree, particularly with such a big cabinet, and large driver...

If a small amount of leakage can impact things so drastically, I think my initial steps at this point will be to install a gasket in the XO panel, and a gasket behind the driver to make sure the cabinet is sound...Then I'll get an amplifier and different CD player to rule out the obvious...

From there, I guess it's back to the XO...

EDIT: I may have to correct myself, but I'm on my way to the airport, so I'll have to validate this weekend...It's been a while since I installed the drivers, but something tells me that GPA shipped a neoprene-type gasket set with them...I'll pull the driver and see if they're installed...