Turn a combo amp into separate head and cab!

[Natesmitguitar]

Hey all! This is my first post in the BFM forum. First, I'll just introduce myself. My name is Nate Smit, son of Tom Smit (some of you may know may know him as Tommo or something like that). I've been a guitarist for 9 years, and that's my main instrument. Otherwise I play drums, can play bass, and even some keys. Right now I'm playing through a Crate RFX-65W 1x12 combo, which is solid state, has 3 channels (clean, rhythm, and lead), and some DSP effects. This amp does the trick pretty well for an SS amp. My tube-using friends have given me compliments on how warm it sounds. In terms of guitar, I use a Yamaha Pacifica 012/112 (not sure which) with some aftermarket knobs and a Seymour Duncan SVR-1 in the neck. I currently have a Bespeco volume/expression pedal and a Boss Blues Driver (BD-2) with a Monte Allum mod. I will soon be buying a PRS SE Custom 25th anniversary edition in Scarlet Red.

So now I get to the good stuff. I recently checked out my amp to see how it was built. It turns out that the head can be removed very easily, which makes me think that Crate had the idea in mind that the users of this amp might want to turn it into a separate head and cab. The head as itself measures 6 7/8"h x 19"w x 5"d (measured including the dropped transformer since it sticks out the bottom of the amp). My main concern is building a head case and worrying about a cabinet later. Given these dimensions and the pictures below, I have some questions: What kind of wood should I use, thickness of the wood, and how should I go about building the chassis? Thanks a lot everyone!

[Mikey]

Welcome, Nate!!!

That's a decent little amp. What I don't understand is why you want to separate the combo. Is the driver blown? Do you intend to build a different speaker cab for it? Please tell us a bit more about what it is you plan to do so that we can give you the best possible advice for your particular situation. We're all glad to help, but the more information that we have, the better for you.

[Natesmitguitar]

I feel like it would be cheaper to use the head part and put it into a wood case like traditional amp heads as well as building a new cab. Right now it's back together (it's honestly that easy to take apart and put back together; good job Crate!). However, my driver is not blown. I'm very interested in the XF212 cab and would use my amp head with that since I do a lot of live stuff (Praise and Worship mostly) which means playing in church auditoriums and sanctuaries. It's just a Crate-designed driver. I might switch it out in the future for something that puts out tighter low end. As far as that goes, I'd ask Crooks about speakers probably. That was my original plan. But I think it's something that would have to happen in the later future because of the good ol' funding tree. I think I got caught up in the excitement of the head having been able to be removed that easily from the cab and jumped to, "What's the next step? BFM forums!" I think I'll be going more the route of building up my pedals. Still, any kind of advice is greatly appreciated!

[loupey]

I just did this to a little bass amp:
http://carvinmuseum.com/decade/92-bassamps.html

I duplicated the original amp mount, i.e., screws from the top. The box is left over 1/2" Arauco with butt joints, PL glue, brads. There is a long heat sink in the back of the amp so I cut out top and bottom vent holes for better passive cooling that was in the original amp. The speaker is a new Eminence CA2010 Basslite...a mistake in my case. I have no intention of keeping this particular box but I happen to have a "spare" CA2010 until I sell it.

There's a thread on DIY cases and may give ideas. If cushioning is important, there are ways to build a box within a box, maybe with foam or springs as shock mounts.

Good luck!

[Mikey]

I'm very interested in the XF212 cab ... But I think it's something that would have to happen in the later future because of the good ol' funding tree.

Well, then just use the combo as-is until you can afford the drivers, wood and hardware for an XF212. Once it's built, DON'T make a head out of the combo! Use it as-is for a practice amp, then unplug the built-in driver and use the XF for "gigs".

What type of speaker-out arrangement is on that amp? Are there two 1/4" plugs, one for the built-in speaker and one for an extension speaker? Is the minimum impedance marked on there?

[Natesmitguitar]

I will be using the combo as-is until I have an extension cabinet. I was reading the manual and checking out the back panel of the amp, and it does not indicate a minimum impedance for the extension speaker. However, when reading mr. Manuel, the schematics indicate that the driver in the combo remains active even when the extension speaker (1/4" out) is plugged in.

I'm wondering if, only theoretically/hypothetically for now, someone could help with a new schematic for a potential 3-way switch where position one would be just the combo speaker, position 2 would be the combo speaker AND the extension speaker (in series as the combo speaker is wired that way) and position 3 would be just the extension speaker (similar to pickup-selecting switch on an HH guitar).

This is my thinking: Pos. 1 would be suitable for bedroom stuff, position 2 would be useful for using the amp as the monitor and pointed at me while the cab is pointed at the crowd, and position 3 where stage volume needs to be kept at a minimum yet the clarity of the guitarist (me) is needed for the crowd. Remember, I am new at this stuff and so any correction and better ideas are appreciated. The extension speaker would be an XF212. Also, the combo speaker is connected via two leads, not a 1/4".

[Gauss]

Playing for churches, the guitar is often mic'ed and sent through the PA, so the guitarist just has to make some way to tilt his amp at himself (and away from the audience). There are a number of ways to do this (my regular guitar player leans his marshall 2x12 against an old monitor), I myself built a cart for my amp (bass amp) that tilts it up.

If you need to fill a room without a PA, and your amp doesn't cut it, I'd recommend building one of the XF cabs and installing your head in it. You could make it as easy to slide in and out as Crate did. I don't believe you'll have a hard time getting loud enough with 65 watts. One band I play in uses only a 5 watt guitar amp. It was modified somehow, but sounds huge through it's little 8 inch speaker.