open back or closed back cab?

[cminor9]

So I just bought a warehouse Veteran 30 and a Reaper (like a beefed up greenback).

Going to build a cab to play my recently built spitfire clone through, also considering a 2 x kt66 Bluesbreaker-ish build in the future.

I cannot figure out what would work best for these speakers? Dr Z's Z Best cab uses a thiele ported cab for the Celestion version of these speakers. Matchless uses similar speakers in an open back cab. Anyone have any experience with these speakers? What configuration do/would you use?

Have also been kicking around the idea of a convertible cab too.

[Steve Conner]

Depends what sound you want really.

An open backed cab gives a big spacey sound that swirls and fills the room, but not much real bass.

A closed back one gives a beefy, chunking bass.

A Thiele cab gives a big bottom end too, but it's more deep and hollow sounding than a closed back. Hard to generalize though, results vary widely depending on how you tune it. Guitar speakers are so non-linear that the regular speaker design software doesn't really work, even if the mfr. can tell you the Thiele-Small parameters the software requires, which many can't.

Putting two different speakers in a single Thiele cab might make weird stuff happen, if they have two different resonant frequencies.

[cminor9]

Thanks Steve!

I am more of an open back cab kind of guy. I guess what I was mostly concerned about is how those particular speakers will sound in an open back cab. I mostly see those speakers in closed back cabs (yeah, yeah, so why did I order them?)

I read some info on Weber's site and they mentioned speakers that have a long excursion and have a lot of bottom end might sound flappy in an open back cab. I don't much about these speakers other than they are a very popular combination and the price was pretty good. I don't want to put these in a cab that won't sound good. I know, I could just change the back and make it open/closed. But they way I have it planned, that extra little piece will step me up to a more costly board.

If nobody is really sure, I'll just build as open back and go from there.

[Bruce / Mission Amps]

Build the cabinet with a partially closed back.
Use two rear panels mounted top and bottom.
Make the rear panels wide enough that there is a 3 1/2" to 4 1/2" air gap between the upper and lower panel.

edit.
That is; two panels with one upper and one lower.

[cminor9]

Thanks Bruce, I think I'll do that. The cab will be 24x24x12, so I think I'll also make another panel so that I can add it to the cab should I want that. Saw a Dr Z cab that does that, seemed like a good idea.

[Bill Moore]

I have read a few posts on the Steel Guitar Forum, where some experiment with the width of the center opening, even in combo cabs. I want to try it sometime, I think the idea is like the THD style cabs.

[Steve Conner]

Once the center opening gets small enough, you have essentially a Thiele cabinet. Larger openings than that give you a more and more badly mistuned Thiele cabinet, as the port tuning frequency rises further and further above the speaker's own resonant frequency. Some people (THD?) like to call it a "detuned" cabinet for this reason.

As far as I know, the sizes of openings usual in open-backed combo amps bring the box resonance up to the lower midrange.

There is a kind of grey area between Thiele, open-backed, horn-loaded and transmission line, a Bermuda Triangle of speaker design if you like, where none of the speaker design software works and you have to navigate by ear. Quite a few guitar and bass cabinets have ended up there over the years.

[Bill Moore]

Another thing, Steve, when playing in small clubs, the bandstand is usually close to the wall, and the open back allows for some reflection,(delay?) off the wall. This also makes for a fuller sound.

[Glass Snuff]

So I just bought a warehouse Veteran 30 and a Reaper (like a beefed up greenback).

While often cited as 'best for closed cab', I've used Reapers in a combo box and they sound fine.

[cminor9]

Well, I got the cabinet done and I built as an open back. I made it so I could convert it to a closed back, but it sounds just fine as is. It has a Warehouse Reaper and a Veteran 30. The speakers aren't even broken in and they sound great! It gives a lot more punch to the little 15w head I plan to use it with and if I build something a bit more powerful it'll handle that as well.

[J M Fahey]

Hi cminor.
Very well made, very professional, congratulations.
Loved the chunky little head too.