Using combo amp as a cab

[dainbramage]

I'm going to build a relatively large ISO box so I can use my amp without disturbing the neighbors. I figured I was going to place a Heritage Victory combo inside of it, but soon realized that it would generate too much heat.

I've got this AC30 that I want to keep and figured that maybe I could use it as a cab inside the box while I'm living in this apartment, and reconnect the speakers when I find a new place to live where I can make some noise. What I'm wondering about is this:

1.) The Heritage Victory is a 1x12 combo, but has several speaker outputs on the back:



Does this mean I can safely insert two speakers as long as they have the same resistance?

2.) Will there be any heat generated by the AC30 if I only use the speakers?

3.) Are the Alnico Blues speakers compatible with my Heritage Victory at all? It has a Celestion G12H in it.

4.) Is there anything else I should know before I go about blowing up my gear?

 

[kip4]

Google up speaker impedance (not resistance)
It would depend with the two speakers if they are in parallel or series.
I'm not sure of your intended set up!!!!!
Do some homework. I'm certain it will pay off
You should be able to greatly reduce the footprint of the ISO cab by just having a speaker ISO cab rather than a combo ISO box.
There's a thread somewhere here about ISO cabs. Try the search function too
Have fun
Rich

 

[dainbramage]

Hey thanks. Yeah, impedance, of course.

My intended setup is Heritage Victory combo -> AC30 speakers inside ISO cab.

I don't mind the footprint being big as I'm not going to move this thing around. You are probably right though, it would probably be better to just have the speaker by itself inside the box but it seems kind of a hassle for a short-term thing. Especially since I intend to use the AC30 as an amp too from time to time. So if it's only a matter of plugging in/plugging out that would be ideal for my use.

I'm not sure about whether they are in parallel or series. Maybe I could just hook up one of them since I will be using a mic anyway?

For what it's worth, here's the amp intended for using as a cab:



Now where are those speaker cables? If they are hardwired is there any easy way out besides picking up a new speaker?

 

[Steenamaroo]

The AC30 will generate no heat if you're only using it as a cab. It wont require mains power either.
The other amp looks to have 4,8 and 16 ohm outputs so you'll be able to work out something. (diagram to follow)

Looks like the ac30 output is hardwired so you'd need to unhook the clips right at the speaker terminals.
Then you connect the output of your other amp directly onto the ac30 speaker.
You'll probably need to make up a jack-to-clips cable for this purpose.

When it comes to using the ac30 again, it's just a matter switching the clips back the way they were.

 

[Steenamaroo]

Here's a diagram that might be helpful.

 

[dainbramage]

I think I'll do this with only one of the speakers as I intend to put a mic there anyway. I just happen to lack any skills in this sort of stuff whatsoever, but I'll see what I can do. Thanks a lot!

 

[dainbramage]

By the way, if I were to put a whole combo amp inside the box, how much ventilation would I have to have? Enough so that the whole point of sound isolation would be gone?

 

[Steenamaroo]

I think I'll do this with only one of the speakers as I intend to put a mic there anyway.

I'm confused. The vox is a 2x12, right?
Even if you only use one of the drivers, you still have to put the whole amp in there.
Sorry, maybe I've misunderstood you.

By the way, if I were to put a whole combo amp inside the box, how much ventilation would I have to have?

Which combo?
The vox used as a cabinet only will require no ventilation.

 

[Steenamaroo]

Forgot to say, be sure to use speaker cable rather than instrument cable.

 

[dainbramage]

I'm confused. The vox is a 2x12, right?
Even if you only use one of the drivers, you still have to put the whole amp in there.
Sorry, maybe I've misunderstood you.

Sorry about that. What I meant was just connecting one of the speakers in the AC30 to the Heritage even while putting the whole AC30 inside the box.

Which combo?
The vox used as a cabinet only will require no ventilation.

I also have a AC4C1. Right now it is inside a wooden box with a bunch of carpets, sleeping bags etc over it. It is closed-miced at a very low volume but sounds really good when I crank the mic preamp and play it through headphones on the audio interface. Has that spark, response, punch etc that any amp/cab sim lacks. That's how I got the idea of using the AC30 as a cab so that I could do the same thing with the Heritage. I didn't realize the speakers were hardwired in the AC30. Should have done more research.

As I only really need clean tones, however, I might just be satisfied with using the AC4C1 like I am now, but inside a better isolated box. I've ordered some soundproofing material but I'm still concerned about the heat. It doesn't seem to run hot under all those layers of carpets however.

 

[dainbramage]

You'll probably need to make up a jack-to-clips cable for this purpose.

I'm almost embarassed to tell you that this is what puts me off. Is that a hard thing to do for a guitar (not electronics) geek like myself?

 

[Steenamaroo]

I didn't realize the speakers were hardwired in the AC30. Should have done more research.

It looks like the output is hardwired (ie, no jack/socket) but don't take my word for that.

Sorry about that. What I meant was just connecting one of the speakers in the AC30 to the Heritage even while putting the whole AC30 inside the box.

Ah, ok. Cool.
Forget the diagrams then and just match the speaker impedance to the appropriate output.

I'm almost embarassed to tell you that this is what puts me off. Is that a hard thing to do for a guitar (not electronics) geek like myself?

Nah, not really.
You could just use the jack-to-clips lead from your pictured combo in conjunction with a 1/4" speaker extension cable - Like a headphone extension cable except heavier. I guess they make those.
Anyway, it's a bit of swapping around but it saves you from having to strip wires and solder, if you're not keen.

If the wires are currently soldered at the ac30 speakers then you're back to square one. You'd have to de-solder them and the best thing to do would be to fit female spade connectors for easy future swapping.



As far as heat from using a complete combo amp in an iso-box...I don't know.
I guess it depends on the amp and how long you run it for. Hopefully someone with first hand experience will chime in.

Not to rock your world, but if you're going to the lengths of making an iso box I'd just buy a 12" speaker to put in it and fit the thing with a jack input socket and an xlr socket. Like this.

 

[dainbramage]

Nah, not really.
You could take the jack-to-clips lead from your pictured combo then buy a speaker extension cable - Like a headphone extension cable except heavier. I guess they make those.
Anyway, it's a bit of swapping around but it saves you from having to strip wires and solder, if you're not keen.

If the wires are currently soldered at the ac30 speakers then you're back to square one. You'd have to de-solder them and the best thing to do would be to fit female spade connectors.

Great, so if they are not currently soldered I could use one of these:


Neutrik NA3 JJ - stereo 1/4" jack adapter (TRS)

And one of these:


Cordial CTL 5 PP, prof. Speaker cable, 500cm, 2x 2,5 mm², 6,3mm Plug/6,3mm Plug

?

I'll look into whether or not they're soldered tomorrow. Thanks a lot for your help, I really appreciate it.

 

[Steenamaroo]

Yeah, that would do it - plus the jack lead shown in your first picture, of course.

 

[ecc83]

Great, so if they are not currently soldered I could use one of these:

View attachment 85670
Neutrik NA3 JJ - stereo 1/4" jack adapter (TRS)

And one of these:

View attachment 85671
Cordial CTL 5 PP, prof. Speaker cable, 500cm, 2x 2,5 mm², 6,3mm Plug/6,3mm Plug

?

I'll look into whether or not they're soldered tomorrow. Thanks a lot for your help, I really appreciate it.

Yes! Way to go. BUT! Do not use any other back to back jack adapter EXCEPT that locking one! All other such adapters are the Devils Work and can go open circuit on you and wreck the amp.

Historically AC30s used two C Blues in series, 8R apiece to give 16 Ohms. Will the external amp be happy with that? And that amp looks like 4 times EL84s for 30watts? If you are using Blues that is the maximum power you should use on them, especially in an iso box since you cannot hear how loud they are getting. (were I in the "business" of Iso boxes I would fit a LED power indicator.)

Also, have you thought about getting the speaker cable out of the box? The exit must be airtight and jacks are not. Even a tiny leak will spoil the isolation by several dBs. I would use an XLR4 and make up a special external lead. (XLRs ARE airtight.)

Dave.

 

[dainbramage]

Not to rock your world, but if you're going to the lengths of making an iso box I'd just buy a 12" speaker to put in it and fit the thing with a jack input socket and an xlr socket.

Historically AC30s used two C Blues in series, 8R apiece to give 16 Ohms. Will the external amp be happy with that? And that amp looks like 4 times EL84s for 30watts? If you are using Blues that is the maximum power you should use on them, especially in an iso box since you cannot hear how loud they are getting. (were I in the "business" of Iso boxes I would fit a LED power indicator.)

Also, have you thought about getting the speaker cable out of the box? The exit must be airtight and jacks are not. Even a tiny leak will spoil the isolation by several dBs. I would use an XLR4 and make up a special external lead. (XLRs ARE airtight.)

Dave.

The external amp is 22w and has 4, 8 and 16ohm speaker outputs. It uses two 6V6 tubes in the power amp section. I think it should be happy with that. Or am I wrong?

Being very short on money at the moment, I think I might just rip one of those Blues out of the AC30, put it in a box and get a few plugs. I can't really use the AC30 for some time to come anyway.

 

[dainbramage]

If I decide to get a new speaker, say a 1x12, how much wattage would it have to handle @ 16 ohm for the 22w amp? Would a max input of 30W RMS be enough if I do not intend to crank the amp? The one that's already in the amp (Celestion G12H) has a power rating of 30W RMS. Does that mean the same thing as max input and so it should be fine?

 

[ecc83]

If I decide to get a new speaker, say a 1x12, how much wattage would it have to handle @ 16 ohm for the 22w amp? Would a max input of 30W RMS be enough if I do not intend to crank the amp? The one that's already in the amp (Celestion G12H) has a power rating of 30W RMS. Does that mean the same thing as max input and so it should be fine?

If you are thinking of a new speaker and are strapped, why the G12H? The G12 Vintage 30 is THE classic rock speaker to a lot of people and is rated at 60W.

That said, yes, the 30watter will be quite safe from a couple of 6V6s (you will be lucky to get 22W out of them anyway!) but a V30 would make the cab virtually bombproof. Shame to "lock away" a Blue anyway! Should be out there, shouting with a pal!!

Dave

 

[dainbramage]

If you are thinking of a new speaker and are strapped, why the G12H? The G12 Vintage 30 is THE classic rock speaker to a lot of people and is rated at 60W.

That said, yes, the 30watter will be quite safe from a couple of 6V6s (you will be lucky to get 22W out of them anyway!) but a V30 would make the cab virtually bombproof. Shame to "lock away" a Blue anyway! Should be out there, shouting with a pal!!

Dave

The reason I was wondering is I can afford a Vox V112NT cabinet and hook that up with the AC41 4w tube amp and sometimes the Heritage 22w. It has a max input of 30W RMS and it's pretty cheap. I decided I'm not going to go through soldering and building anything to incorporate the speaker by itself as I am a complete noob at those things. I just need a fairly isolated box to keep a close-miced speaker in and even in the box it will stay at low volumes (I'm not aiming for a cranked breakup sound). Isolation doesn't have to be perfect. I'll rather just put the V112NT cabinet in the iso box. So if I can use that cab with the Heritage too when I'm not using the Heritage for jam sessions etc, that would be great.

LINK: VOX Night Train V112NT 1x12 Guitar Speaker Cabinet at zZounds

 

[dainbramage]

If the wires are currently soldered at the ac30 speakers then you're back to square one. You'd have to de-solder them and the best thing to do would be to fit female spade connectors for easy future swapping.

They are indeed currently soldered at the speakers so I'll think I'll just leave the AC30 as it is.