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Small guitar tube amp for bass?

superhand

superhand

Sep 14, 2009
173
0
Fresno, CA
#1
So ideally I would like to eventually get a real nice bass tube amp to get a nice natural overdriven sound for my bass but I definitely can't afford one right now.
Meanwhile I have a Vox AC4TV all tube 4w @ 16 ohm guitar combo amp with a 10" guitar speaker. It's all stock except I cut off a big piece of the back panel to make it an open cab.
I have used it with my Fender Jazz bass in the past and it sounds pretty damn good just the way it is and I don't think that I have damaged the speaker at all as far as I can tell.
I have a 5 string active bass now too with a low B and I have not tried that with it that yet.
I'm thinking about getting a 10" bass speaker for it and maybe do some other mods to it to make it more bass friendly.
Any thoughts or suggestions for me?
Thanks.
 
#5
superhand said:
The amp is 16 ohm though. Why do you say a 8 ohm driver?
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Because he missed that part :D But I'll tell you...I can't say for sure if your little Vox is one of them, but generally, tube amps withstand a 2:1 impedance mismatch just fine. Might sound a little more compressed, but usually won't damage the amp or cab. Should get a second opinion specific to your amp, though, from someone more knowledgeable than me.
 
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#6
I actually vaguely recall seeing somewhere that you can run the AC4TV with a 8 ohm speaker and it works fine and actually makes it louder. That was for guitar though.
I've also thought about just leaving it as it is but I'm concerned that I will blow out the speaker. I feel like running it at 1/4w (it has a built in attenuator) should be pretty safe even with the volume dimed, but I don't know.
 
#7
superhand said:
The amp is 16 ohm though. Why do you say a 8 ohm driver?
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For the same reason that jM gave; the amp will more than likely be able to handle an 8 Ω load just fine, 16Ω speakers for bass are quite uncommon so an 8Ω will be the best next thing. Even most of the old Fender tube amps can handle a 100% impedance mismatch just fine, as Leo expected such and designed his amps to be able to handle it.

Oh, jM, I did not miss that part, I just went straight for the throat of the matter. :woot:
 
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#10
lfmn16 said:
Let your ears and common sense be your guide.

I play bass, guitar and keyboards through my 35 watt single 12" Fender Deluxe at personal practice volume. It's never been an issue.
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This. :thumbsup:

@superhand - I've put many different basses through dozens of small guitar combos (most recently an Orange Crush) for low volume practice (and a few times while recording) with no adverse effects to the amp. Just watch your levels (as you already seem to know) and you'll be fine.

I'll also routinely plug into my GFs Fender Lead 75 on the 15W setting for impromptu quick jams. I just watch the level, leave the EQ flat, and occasionally put the reverb on 1 to open things up a tiny bit. Sounds great for the type of stuff I tend to play.

For ABG I use a small Yorkville Bloc40K keyboard combo amp by choice. And I'd highly recommend the more fullrange keyboard combos for an ABG over a traditional bass amp.
 
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#11
superhand said:
So ideally I would like to eventually get a real nice bass tube amp to get a nice natural overdriven sound for my bass but I definitely can't afford one right now.
Meanwhile I have a Vox AC4TV all tube 4w @ 16 ohm guitar combo amp with a 10" guitar speaker. It's all stock except I cut off a big piece of the back panel to make it an open cab.
I have used it with my Fender Jazz bass in the past and it sounds pretty damn good just the way it is and I don't think that I have damaged the speaker at all as far as I can tell.
I have a 5 string active bass now too with a low B and I have not tried that with it that yet.
I'm thinking about getting a 10" bass speaker for it and maybe do some other mods to it to make it more bass friendly.
Any thoughts or suggestions for me?
Thanks.
Click to expand...

Don't even think about trying to play that at gigging volumes. First of all it would never be loud enough, and second with your now "open back" there is absolutely no damping on a speaker that wasn't made to handle bass in the first place. If you start getting a decent volume out of it, you'll shred that speaker. There's a reason guitar cabs have open backs and bass cabs don't. Back in the 50's Fender came out with a 410 Bassman amp with an open-backed cab. It ended up being a good guitar amp but the speakers would come apart when subjected to normal bass playing as they repeatedly smacked into their maximum extension and tore the speaker apart. XMAX wasn't even something they designed around back then.

At the very least you need to plug it into an extension cab that is a REAL bass cabinet.
 
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#12
Also, if you really want a tube amp, you're going to need one with same good wattage. I attempted to tour with a 50-watt 1966 Fender Bassman tube amp in the early 70's and had to upgrade to a much higher wattage amp because I was getting buried by the guitar and keys.

You'd probably be better off getting a Solid-state amp with a tube in the gain section so you can get that overdrive sound, or just get a pedal like the Eden Glo-plug. Street price is $149 (GC) to $199 (everywhere else). Here's a vid showing what the Eden one will do (cued up past the ugly intro).

 
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#13
It all depends on the venue and on the efficiency of the speaker.

Gigging with just 50 W is possible, but You'll need something like 215 cab with a pair of EV15Ls or such. And You should use a high pass of about 70 Hz which will give more power to the musically more important frequencies. Writing this - without going through the PA...

But for small locations not allowing to play really loud an amp with about 10-20 Watts on, say, a TL806 clone, could make a really good job.
 
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#16
Rip Van Dan said:
You'd probably be better off getting a Solid-state amp with a tube in the gain section so you can get that overdrive sound, or just get a pedal like the Eden Glo-plug. Street price is $149 (GC) to $199 (everywhere else).
Click to expand...

Although a 12AX7 based pedal is going to get you closer to the tube sound than not having one, it still isn't going to deliver what many people are hoping for by way of a tube head. Because that sound comes more from the tube driven power amp stages in a tube head than it does from the preamp. Which is why hybrid amps with a tube preamp stage get some of it. But not enough to push all-tube amps completely off the stage (would that they did.)

Another consideration (to my ears at least) is that a 12AX7 sounds different if it's being run in a pedal at low voltage, as opposed to high voltage in a tube head. It seems to loose a little of that harmonic sweetness it's known for. Although it's still better that than nothing I'd say.

But there are less expensive alternatives that might put you in the ballpark just as well as the Eden which might be worth considering. A company called ART has an inexpensive tube "microphone" preamp that gets used a lot by recording enthusiasts to capture some of that tube vibe. And more recently musicians have been trying them on their pedalboards and reporting good results. There's two versions dubbed the MP Studio ($50) and MP Portable. For around $50 neither will break the bank for most people. There's now a new version (MP Studio V3 @$75) that has a voicing selector (including a "warm bass" setting - so somebody at ART must have been listening) that also looks promising.

Might be worth a look.


IMG_2738.JPG IMG_2739.JPG
 
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#20
As others have said:

#1, an extension cab, namely a bass cab without a tweeter, would be a beautiful thing.

#2, barring that, a bass driver, maybe one of the new eminence ceramic legends that comes in 16 ohms, could probably handle the bass better than the Celestion driver in the combo, because it's designed for those lower frequencies. Of course, an open-back bass cab is a recipe for broken drivers, but I think wth a 4 watt amp and 3mm of excursion, you should honestly be fine IMO, I have a 4ohm 8" car woofer in an open back 3-watt tube amp, and it rolls on a 5-string bass just fine. Don't point at me if it blows up though, I'm not an expert ;)

#3 keep expectations in check, as I'm sure you know - it's a 4-watt amp, you're not going to get too loud unless you Daisy chain like four 810 cabs and work out the impedance somehow.

#4 look into whether The combo speaker disconnects when you hook up an extension cabinet, if it does, you could just plug into a bass cab when you want to play bass through it.
 
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