Hi Buzzer,

Before you start building let mi tell you couple of very recent developments.
29th of March I was invited to Larry Carlton’s sound check to show him Thunderbox and my OTS.
Larry was using Bludodrive 100 w head and Bludodrive 1x12 EV loaded cabinet, both made by Brandon Montgomery. It was really great sounding combination. Only problem for me (not for Larry) was EV’s killing directivity on axis, off axis tone was great.
Larry really liked Ceriatone’s tone (congratulations Nik) but it was not powerful enough for him (my amp is 50w only) and he likes 100 watter.
I have to admit that Larry did not like Thunderbox for two reasons:
1. I had Celestion Century neo in it and tone was bit OPEN for him.
2. Because of reflections from the top and the beck of the cab, some notes were phzasing.

Larry suggested to cover the top and the back  of the cab with 50mm egg crate foam and change the speaker. I’ve replaced the speaker with Jensen Tornado neo100 and covered the cab. It sounds great now but it has to much bass.
I’ve realised that port on the bottom was to small or it MUST be on the front side of the speaker compartment.
You can have two or three 10 cm diameter ports and if you wish to change the tone you can cover one or two from inside with large plywood circle and screws.

Tone on my thunderbox (I’ve enlarged a bottom hall to 25cm) is so smooth now that I don’t want to go back to 2x12. and it records great too via inner mics.

Hope this helps

Cheers 

Never fear Skydog!

After the OP I was embroiled in helping a friend get back into Thailand, who had been blacklisted from here because his name 'sounded like' another man's name. I guess that Thai immigration has a penchant for rhymes. But that's too much stupidity to deal with as this is OT anyway.

Anyhow, I couldn't respond to Pickmaster until now. Thanks Pickmaster for the sage advice. A lot of that makes perfect sense.

If you could provide a photo after the modifications, that would help - as we all know a picture is worth a thousand words.

The way the cabinet is originally designed, it's going to have good stage coverage anyhow, so the porting is mainly to diminish the bass response, correct? There would be no problem putting the 1 X 10 cm. ports in the front, as far as I can see. It wasn't clear to me if you did that as well, or just enlarged the port on the bottom. Could you clarify?

I don't have any kind of vast knowledge about acoustics, and I want to build a couple nice speaker cabs for the 3 speakers I have on hand. The Thunderbox sounds like a good option for my EV-M12L. It's nice that you are experimenting on the thing to tweak it to the right specifications. I want to have a pretty good idea of how it's going to be built before I start. Duh!

The idea of a bottom port kinda threw me though. From my experience with some speakers and subwoofers, the conventional wisdom is that they shouldn't be placed too close to a wall. Well, what's a floor? Just a wall lacking an upstanding character. It seems like the Thunderbox is porting to a very solid wall instead of into the room. That was the one thing that bothered me about the Thunderbox.

Do you have any more to say about the on-Axis, off-Axis nature of Larry Cooltone's speaker? - Chances are it's an EV-M12L. Mine would be handling far less wattage as the overtone isn't even 50 (I forget the exact wattage). Also, any clues as to how this speakers directionality would work with, or against it when placed in a Thunderbox type configuration?

This is probably going to show my ignorance regarding the mechanics of sound, The phasing must have been in the more audible upper mid range, or the egg crate foam wouldn't have helped much, IMHO. I'm wondering if diffusion might be better in this case than absorption?

Regarding mics - it looks like 2 Shure SM-57s. Is that right? I only have 1 of those, which is not available as I use it for blues harp. I can experiment around when I get the cab made. I have a weird mic that would be my first choice for experimentation. It is an Audiotechnica AE2500, it's supposed to be a kick drum mic, but, like I said, it's weird. I've used it for a lot of things because it is a dynamic & condenser mic all in one body. Thus the one signal is quite different from the other, and needs to be treated as two mics in stereo, and EQ for each is different, of course. I know how much you guys like pictures, so I'll go find some on the internet.
Well, I'm back! But not knowing how to manipulate the photos, WYSIWYG. Sorry if they're too big, or small. My last post, the pictures came out really small.

This is just one of several projects I'm into to upgrade my OTS. FWI, the others 1.Mentioned before - a 2X12 cab for the greenbacks. 2. I really need some basic effects (but good ones). 3. Upgrading almost all my guitars with new pickups. 4. Bringing my long-dormant home studio into the 21st century. So I may be asking advice in this and other forums regarding all this madness.

Thanks for listening to all this drivel.

Buzzer

Hi,

Thanks for the updated pics. If a picture is worth a thousand words, you said a mouthful!

Did you maintain the port facing the floor, or did you patch that over?

I really would like a speaker cab that is a little (or even a lot quieter) because, while I'd like to, living where I do in Thailand (far from any of the places where playing is easier - like Bangkok, Phuket or Pattaya) I just Don't Get Around Much Anymore. In fact I missed the Saturday dance.

Also you clarified what mics you had in the Thunderbox.

Thanks - Buzzer

Larry like the Overtone?

thats cool.

Marin

A few weeks back in the Netherlands he used every footswitchable item on his Bludo 

I've thought a lot about this, and my first cab i'm going to build is the 2X12. This one is for a project - down the road - but maybe not far down the road.

Regarding the 2X12 (w/ Celestion 25w greenbacks, I still want to make a race-track (eliptical?) shaped port. The closest example I found here: http://www.hermidaaudio.com/
Here's some pics (I'm mostly interested in the back. The front view, I'd like to have some grill, or screen cloth to protect the speakers a bit.

I would also probably find a way to close the back when I want to - for some dumb reason.

Anyway this would be a great cab with nice speakers, and probably loud enough for me.

However. I've spent a lot more time since Pickmaster provided all those details about his Thunderbox, and experimentation with it, and I got to thinking (that's always trouble). And I can use something like that, but I could really use an isolation cabinet in my house, too. Then I got to thinking, why not have a convertible? The Thunderbox is already miced, as would be the isolation speaker. So all that would be required would be (for a less isolated version) would be some doors, or a cover. For more isolation, a complete outer box. I was surprised at one that I found on the net that, in a way, looks a little like the Thunderbox. It's called the Demeter SSC-1 Silent Speaker Chamber. Gee, it's not called a cabinet anymore, but a 'chamber'!http://www.demeteramps.com/products/cabinets/ssc1.html

Anyhow I haven't figured out how to put these photos in the right place on the page, so they'll end up grouped together at the bottom, I guess.

Let me know what your thoughts are!

Thanks - Buzzer