A full-range cab for a guitar tube amp?

First, a little background:

I have no room for a real Hammond or a Leslie. As a result, I'm thinking I'll be forced to use one of the various simulated Hammonds out there. I'm told, though, that they sound really good, as long as you run them through a real Leslie.

Problem is, the Leslie is the part I don't have the room for. I might even be able to handle an M3 or similar if I got rid of the Optigan. It would be in a room on the other side of one of the recording room's walls, but I can always snake a cable around.

So, I'm thinking of taking a more "Jon Lord" approach and am now wondering if I could make a sort-of full-range cabinet for a guitar head. It would have to be small, but there is some flexibility in the design. It definitely would not have to be monitor quality; in fact, the idea is for it to add it's own character, as I've noticed that Hammonds going through nothing but a clean loudspeaker tend to sound somewhat flat.

I'm thinking that a basic woofer-tweeter combo with a crossover, like any typical speaker, would do the trick, fed from a guitar head.

Any thoughts?

PS: Something like this might be cool for analog synth recording, too.

Now that I think of it...

Is there any reason I couldn't take a guitar amp out to a bog-standard two-way speaker, as long as I match impedance? I'm thinking in terms of not blowing stuff up.

What you want is a Keyboard Amp. Looks like a guitar amp, has extended response. I have a Roland Keyboard Amp that I use for general utility work (including keyboard).

> Is there any reason I couldn't take a guitar amp out to a bog-standard two-way speaker, as long as I match impedance? I'm thinking in terms of not blowing stuff up.

No.

Do note though that a guitarist with a 40W tube amp will quickly destroy a "100W" Hi-Fi speaker. Hi-Fi is about NOT clipping, much 'lectric guitar tone IS clipping. A "100W" Hi-Fi speaker will only get 10W of long-term heat in Hi-Fi use; but several-second bursts of 30-50W with a lively guitarist and a 40W amp. Home Hi-Fi speakers will rarely stand over 20 watts for more than 10 seconds.

I don't know if a Hammond, or your Hammond(clone), "needs" to be played to distortion. And of course it depends on the player and the crowd and the drummer.

The organ has a wider range than a guitar.

Guitar starts at 82Hz, a full pipe organ runs to 32Hz or 16Hz. Obviously a Leslie does not have strong output at 16Hz; my guess is that a Leslie booms like a good Fender-Bass amplifier, ~50Hz, and such a speaker is what you start with.

Guitar pickups generally drop off at 3KHz-6KHz. Guitar distortion will sit higher, but not over 6KHz. The speakers they use get very beamy above 2KHz. The few guitar amps with tweeters have been flops.

OK, exception. It has become more common to amplify "acoustic" guitar, and the amps sold for that specific purpose often do have tweeters to spread the string-screech around the room.

For Power: a 15" bass-guitar speaker in a 2 or 3 cubic foot box will get Leslie-size bass up to maybe 1KHz. Of course it is nearly the same size as a Leslie. Set an 8" guitar speaker on top, no box, 10uFd-22uFd NP cap in series to block the bass. Mike on-axis, and a "brite" 8-inch will run to 6KHz. I really doubt you want a midrange instrument to screech above 6KHz; if you do (Dead's "Unbroken Chain", Doors' "Riders On The Storm") then add a 10-buck piezo tweeter.

You could also use stage speakers, the 12"-15" woofer with tweeter in a box used in clubs. They are never flat, sometimes fun.

If this is strictly recording: play soft, around 85dB SPL slow-response, and any modern Hi-Fi speaker 8" woofer or bigger will do the deed. The old $99/pair Yamaha speakers are un-flat but pleasant and often more "interesting" than a good monitor.

If you "must" distort: consider a Fender Champ (you should have one anyway, the one-6V6 series, not the Super Champ) or a Epiphone Valve Jr Head ($99 at any Banjo Center) into a Hi-Fi speaker sourced from a garage sale or your brother's attic.

You mean like this?

http://www.angela.com/catalog/how-to/Single.6V6.html

I'm thinking I could handle building one of those.

Yeah, a keyboard amp is basically what I was going for, but one with character, rather than most keyboard amps which are typically designed to be clean and relatively flat.

Thank you for the reply. You've confirmed my suspicions. As is usual, it's always after my first post in such threads as these that I think of a better approach than my original idea. I'll at least have a few ideas to play around with once I get the money problem sorted out (hopefully soon).

[quote author="PRR"]Do note though that a guitarist with a 40W tube amp will quickly destroy a "100W" Hi-Fi speaker. Hi-Fi is about NOT clipping, much 'lectric guitar tone IS clipping. A "100W" Hi-Fi speaker will only get 10W of long-term heat in Hi-Fi use; but several-second bursts of 30-50W with a lively guitarist and a 40W amp. Home Hi-Fi speakers will rarely stand over 20 watts for more than 10 seconds.[/quote]

In a recording situation, I probably won't need more than a few watts of output power. That little Angela amp probably doesn't put out any more than 10 watts or so.

> That little Angela amp probably doesn't put out any more than 10 watts or so.

It is max 5 Watts sine-ish, 10 Watts gross square-wave heat.

The Epi Valve Junior is similar in topology and power. You can see it as a pre-built semi-Champ at a price so low that it begs to be messed-with. It has all the right parts in mostly-OK quality in the right places. Considering it is 1/5th the price of a Fender-style Champ kit, that's a steal of a deal. For organ, I think you'd want a bit of NFB around the EL84 and OT, larger coupling caps, and fiddle the Brite cap network.

Thank you very much for the information, PRR. This thread definitely gave me enough ideas and info to play around and find a solution.

You might want to go with an edcor output transformer instead of the hammond 125ESE they mention. The edcore will give you more output on the low frequencies, but you do not get the multipul impedences of the hammond.

Lots of organ players out there use guitar amps for their organs. John Medeski had at least a dozen guitar amps on stage when I saw him at the New Orleans Jazz fest years ago. The only amp he had on stage that was not a guitar amp was his leslie. It was an impressive pile of amps and mics.

adam

Thank you for the advice and tips, PRR and adamasd. I definitely think I can experiment and arrive at someplace interesting now.

And now that some of my consulting work is finally paying off, it might be sooner rather than later. :grin: