Can I use a 40 watts preamp on a pair of 80 watts speakers?
Home > Home Recording Forum > Gear Gab > Can I use a 40 watts preamp on a pair of 80 watts speakers?
Posted on Feb 05, 2010 05:39 pm
Marius
Member Since: Jan 17, 2010
Hey, I have this small guitar amp and I think it sounds pretty awesome and I have this Vox ac30 (160 watts) and it's ok but I don't like the overdriven sound of it. So my question is, Could I just take out the preamp of the small amp and just plug it into the speakers of the vox Ac30 or wouldn't this work since the small one is only made to power 40 watts I think? since it's 160 watts I guess it's 80 per speaker so maybe I could power just one? Or would it be possible to just connect the other preamp and leave the vox on too and just turn it all down on the vox ?
Thanks...
[ Back to Top ]
pjkPrince CZAR-mingMember
Since: Apr 08, 2004
Feb 05, 2010 06:55 pm Well, since you're taking signal from the output of the preamp, then the output power has no bearing. Meaning it doesn't matter what wattage the first amplifier is, because you're not using the amplifier, just the preamp.
Now, be sure that you're taking signal from the preamp. Preamp out sounds like the right spot, but just want to be sure so you don't kill something.
I don't think you'll be plugging into the 'speakers' of the ac30. I'm gonna assume you'll be plugging into the 'input' of the ac30. This isn't really a great idea, but it's not totally un-doable either. The preamp out is probably a LINE level signal, but the AC30 wants to see an INSTR level input, usually between MIC and LINE level, more towards MIC i'd guess. So if you turn up the preamp output (or maybe gain) then you may be sending out too much of a signal and overdrive the input circuit on the AC30. This may damage the input circuitry, so if you're doing it this way, I'd say keep the volume down on the first preamp, so you don't destroy the second input.
Now, I don't think the AC30 is 160w, more like 30 - 40. Here's snippet from WIKI:
The EL34 powered AC30 was short lived, and was soon powered by a quartet of EL84 (6BQ5) power tubes.
That 2 el34 or 4 el84 gives somewhere between 30 to 50 depending on circuitry. But this is probably irrelevant. Also doubt the AC30 is stereo, meaning separate signals to each speaker. I'd guess that it's sending 1 output speaker signal to both speakers.
If the VOX has a "Power Amp IN" jack, then plugging from the first amp preamp out, to the VOX power amp in would be the way to go.
Also, if you're getting a good sound from turning up the first amp, then you're probably not going to get the good sound by just using the preamp of amp 1. Some of the good sound may be coming from the amp1 power section. I don't really know, because you didn't mention what amp, how it's set, configured, played, etc.
Hope this helps, and post more info if you're still not sure. I'd hate to see a AC30 get munged up.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Feb 05, 2010 07:34 pm If the AC30 isn't doing it for you then I'd happily take it off your hands for a discount :-)
Yeah, the AC30 is named for its wattage: 30 watts. But its one of the loudest 30 watt amplifiers ever. Just cutting, biting tone that launched the British invasion in the 1960s.
There are only a couple of ways that you can hook this up and not fry anything. And those AC30s are too good of an amp to fry in an ill-thought out experiment.
Which particular AC30 do you have? There have been several different variants and reissues of the Vox AC30 over the years. Look inside the chassis and see if you can come up with a model number. That will make a big difference on how you can hook this up, or if its even possible at all.
If both amps have an effects loop, you can go from the FX send on one amp to the FX return on the other amp. That will allow you to use the preamp of one amp but the power section of another amp. The FX loop deals with line-level signals, which are safe to send from the FX send to an FX return or maybe from an FX send to an instrument input, provided you have a trim pot for the FX send to keep the level within the range that's acceptable for an instrument input.
If none of this makes sense to you, then I recommend not trying it because the chances of doing irrepairable damage to one or both amps is relatively high. All it would take would be to send an amplified signal into a line or instrument input and it's bye-bye amplifier.
Let us know model numbers and brand names for both amps before we give you any concrete advice on trying this.
MariusMember
Since: Jan 17, 2010
Feb 06, 2010 01:11 pm So it's a Ac30 but I don't know any more model numbers or anything. And I'm pretty sure it's a 160 watts, I bought it used so I think maybe he changed the speakers or something and it's 2 years old. The other one is just a cheap woodrock amp, it's not a great amp at all but I find the sound I get with low gain and high volume pretty awesome.
So would it be better to just use the Vox as an external speaker ? Does that work? Cause I've got an output on the small amp that says external speaker. Cause I want the preamp of the amp to work without being influenced by the vox preamp.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Feb 07, 2010 11:50 am The Vox AC30 is 30 watts, hence its name. It's a classic amp in the rock world and is well-documented as 30 watts. It's little brother, the AC15, is 15 watts. Its big brother, the AC100, is a 100-watt head...you get the picture.
Anyways, do NOT plug the Woodrock's speaker output into anything in the Vox. There are no speaker inputs on a vox amplifier, nothing that would accept an amplified signal. You'd fry anything you'd plug that "external speaker" jack into. The ONLY way this would work is if the Woodrock has an effects loop. Then you'd send the FX send of the Woodrock to the FX return of the Vox.
The external speaker jack is meant to be sent to an extension cabinet, which is what it sounds like what you really want here. That's simply a speaker in a box that you can plug into your Woodrock via a speaker cable (not an instrument cable, although they look very similar). You can buy extension cabs or you can build your own. Depends on your budget and carpentry skills. An extension cabinet doesn't amplify the sound at all, but it does help increase volume by adding another speaker (or two, or four) to push more air. You just have to buy a cabinet that matches the output impendance of the Woodrock.
It's just a shame to use an amplifier that's reknowned for its awesome tone to simply amplify the preamp signal of some off-brand amp. To each his own, and I shouldn't judge, and all that...but dang.
The Vox AC30CC2 (which is probably what yours is, if its only 2 years old) is currently selling new for $1200 or more ($1800 if it has the Alnico Blue speakers in it!), and used for about $900 or more. If you don't like its tone, there are thousands of people out there that do. It's a gem of an amp.
Have you tried cranking up the AC30 yet? It's a raging beast, I tell you. I don't know too many people that don't like the way they sound. Actually I don't know anyone that doesn't like the way a cranked AC30 sounds. Loud s.o.b. but its such a rich distortion, its sublime.
OK, enough of the lecture. Carry on.
MariusMember
Since: Jan 17, 2010
Feb 07, 2010 12:01 pm I'm not sure which speakers that are in it but I don't think it's the alnico blue ones. I've tried cranking it yeah, and I love the bass I get out of it and how loud it gets but the overdrive is not that great, I think it sounds kinda thin but I'm playing with some stomp boxes so that's fine. I thought it would be possible to just plug it from "external speaker" to the input of the vox.
Another question, if I crank my amp a little I get this buzzing sound ( the vox amp) and I don't know why, even if I turn down the bass I get this almost like something is shaking or something. Anyone know why?
pjkPrince CZAR-mingMember
Since: Apr 08, 2004
Feb 07, 2010 01:25 pm Quote:
I thought it would be possible to just plug it from "external speaker" to the input of the vox
Absolutely not!
Like Tad said, immediate damage would occur.
I'll lay out a few of the components you're working with:
1) Preamp. This is in both amps. The preamp takes instrument level signal (well under 1 volt) and boosts it up to line level (around 1 volt).
2) Power Amp: This is in both amps as well. This takes line level signal and boost it up to output level signal (watts).
3) Speakers: These are in both amps as well. These take Output level signal, usually referred to as watts.
So, the external speaker output on your woodrock is sending OUTPUT level signal, which may be 5, 10 or whatever volts, in the order of maybe 15 watts. If you plug this level of signal into the preamp of your VOX, then the preamp circuit on the VOX will be toast. Very quickly too, i might add.
So to make a setup like this to work, ideally you would tap signal out from the woodrock between the preamp and the power amp. This signal could be fed into the power amp of the vox. But if you don't have connection points to do this, then you may be getting into trouble. Like I said above, if you have a 'preamp out' jack on the woodrock, then you can send this to the VOX, but there's a chance you can send too much signal, and damage the input on the VOX. Not a good plan.
Here's another scenario that could work:
Play woodrock like normal.
Microphone on woodrock speaker.
Small mixer or external preamp.
Output of preamp (line level) send to input on vox, but very low on output of preamp.
This will give you the sound of the woodrock, but amplified through the VOX.
What may be a better solution is to sell the VOX and get a amp that you like. This way the AC30 stays the way it is supposed to, and you don't have to worry about killing something, and then still having to come up with a different solution.
MariusMember
Since: Jan 17, 2010
Feb 07, 2010 03:11 pm Okey thanks for the answers, The woodrock does not have any effects loop btw.. So good I asked before I tried it and fried my Vox.
So any suggestions on which amp would suite me ? I like a lot of mids and not to much trebled sound. I'm looking for a kinda sound like Joe Satriani, Steve Vai etc with a warm sound.
TadpuiI am not a crook's headMember
Since: Mar 14, 2003
Feb 07, 2010 08:13 pm Yeah, the Vox is a classic British voicing, which is a little more midrange and treble. It sounds like you'd like a more "American voicing", so to speak. Mesa/Boogie might be right up your alley. Normally they're tough to suggest due to the cost. But man, since you're sitting on a veritable gold mine of an amp with your Vox, you might be able to pay for at least half of a new or used Mesa combo if you sell/trade the Vox.
Joe Satriani has a signature series of amplifier that he released through Peavey. They get good reviews and are very versatile amps. The JSX series is the name, although they're mostly very high-powered amps that would be tough to open up loud enough to saturate the power tubes and enjoy their true tone. The heads are like 120 watt tube amps, which is a silly amount of power. But if you can play loud or get a power attenuator, they might be up your alley.
Steve Vai plays thorugh Carvin amps, I believe. At least he endorses them. I saw part of his "Where The Wild Things Are" on Palladia a few weeks ago and I didn't note what amps he had behind him, they were kind of obscured in the darkness. Of course he uses so many effects that its tough for me to tell what comes from his amp and what comes from his pedalboard.
Well, at least those are a few ideas that you might want to try out. Any tube amp that you audition, see if its possible to really open up the master volume on it and get it towards the top end of its power output range. That's where you really get to know a tube amp.
And don't forget that you can always use an EQ pedal, an overdrive pedal, or maybe a distortion pedal to change the character of your current amp's distortion. I agree that the AC30 is a piercing amp on the high frequencies. Especially if you enable the top boost, man its painful. Maybe an EQ pedal to tame the high end and boost the low mids would make the AC30 more to your taste. I recently got an MXR 10-band graphic EQ pedal and I'm starting to wonder how I ever got along without one. It can change the character of my amp so drastically, or I can put it after my TubeScreamer and really tailor the distortion I get to my tastes. Just another idea to kick around.
Good luck!
MariusMember
Since: Jan 17, 2010
Feb 08, 2010 03:32 pm Thanks, I guess I will consider a new amp but not yet. I actually just bought an Eq pedal ( Boss Ge-7) But I haven't tried it with the top boost channel of the vox cause it sounds so painful that I'm used to never use it. haha. I will definately try it!
MariusMember
Since: Jan 17, 2010
Feb 19, 2010 01:41 pm So I checked my amp and it's a Vox CC2, my bad I thought it was 165 watts cause it says 230v / 165w but I guess that's just into the preamp to power the whole thing? And there's a pair of speakers 30 watts each.
