Tube power amp direct recording question

WarmothRules

Senior member
Messages
313
My band is doing a little 3 song demo pretty soon and I want to use my berhinger V-amp which sounds good and clean enough for this. I'm doing my guitar tracks at home to a metronome first. Just wondering if it's safe to use a tube power amp with it not plugged into a cab. I was planning on running my berhinger into my peavey classic 120 tube power amp which has a direct out XLR connection. I would think I'd get a little smoothing out of the digital sound with the three 12AX7 preamp tubes inside my power amp. I think I read some where that a tube power amp needs to be plugged into a cab while the standby is off but i'm not 100% sure.
 

WMHOLP

Senior member
Messages
173
I dunno what kind of tube power amp you're talking about; but, you shouldn't run it with no load on the speaker outputs.  On the surface anyway, it doesn't sound like a good idea, unless you can switch it to a dummy load for the output transformer and have a line / recording out.

For my direct recording, I have a POD 2.0 that I use in front of a 2-channel tube pre-amp that feeds my USB interface to the computer / recording software. Very simple setup, nothing fancy.
 

-CB-

Senior member
Messages
5,427
1.  You need a load on the output, or you'll run the risk of frying your output transformer.

2.  Tube amps generally should really bad with a static load, such as a resistor. 

You will need a true dynamic load, and no matter what hompus-pompus Ted Weber (stuffed brain at famous speaker Co., in spite of his son) says, the blowhard is wrong about his "mass".  Similarly, Gerald Weber (oily amp Co fame), out hot winding TW, has no clue. 

The thing with tubes, outputs... the dynamics of a speaker change constantly.  The impedance presented by the speaker load changes even as the VOLUME changes, regardless of the frequency.  That is - speakers are dynamic, and coils moving thru magnetic fields generate a bit of "feedback" to the output.  Things such as damping factors of outputs deal with this in a variety of ways, but they do not do it well, by design, on guitar amps.  Guitar amps are meant to be loose sounding, and with speakers connected they are.  Put a load on - even one that uses a "real speaker coil" and its not the same, as that coil is not sprung by a cone on a frame with spider.  That is, the coils MOVES, and the force on its movement, and its velocity depend on how far it moves, which in turn is a direct relation to the volume at which its driven.

Use the speakers.

 
N

neilium

Guest
What CB said.

Dummy loads are great for the test bench, but every one I've ever tried is just tone pollution. Also, it sounds to me like your power amp is a solid state amp with a tube front end. I don't see what you'd gain tone-wise by including that in the chain and not using a speaker.

So, use a speaker and use a mic. Doesn't have to be a good mic; go to your local pawn shop/junky used gear store and get an SM57 or something comparable. Spray that badboy with lysol (pretend you're buying a used toothbrush and handle accordingly.) Experiment fearlessly with placement and volume. You can't break anything except the terms of your apartment lease.

As convenient as direct recording is, the recording process really comes to life when you actually capture sounds that are in the air. Look at it this way: everyone knows what direct recorded guitar sounds like, and we're all painfully familiar with every preset on the POD, but nobody in the world knows what your bathroom sounds like when it's getting rocked with an amp on the toilet and a mic in the bathtub. You owe it to the world to share that tone.
 

Alfang

Senior member
Messages
2,596
-CB- said:
1.  You need a load on the output, or you'll run the risk of frying your output transformer.

I disagree, the wrong load may be bad. "No" load is no problem      no load means no current flow, no current flow means no heat, no work no whatever.

So alls you have is something switching nothing flowing, but I get your jist, and agree with all but no load condition

OOPS, I may have missread,  by load you meant more than Zero ohm load, more likely 8 ohms? no load could be a dead short, as opposed to open, infinate load
 

nathan a

Senior member
Messages
1,836
neilium said:
nobody in the world knows what your bathroom sounds like when it's getting rocked with an amp on the toilet and a mic in the bathtub. You owe it to the world to share that tone.

I really, really like how you phrased that. Kudos.

Also, consider two mics. For example, one in the tub, one outside the room in the hallway.
 

-CB-

Senior member
Messages
5,427
Alfang said:
-CB- said:
1.  You need a load on the output, or you'll run the risk of frying your output transformer.
I disagree, the wrong load may be bad. "No" load is no problem      no load means no current flow, no current flow means no heat, no work no whatever.

Alf,
Please don't cloud the issue.  No load - an infinite load, open...  is bad, very bad for tube amps.  Because no current flows on the secondary does not mean none flows on the primary side of the output transformer.  This is very bad, will result in a blown primary, even on the exceptionally over designed Fender amps of the 60's/70's.

Most tube amps - will actually short (zero ohms, dead short) the output when no plug is in the output jack.  That is to prevent the output from tearing itself up.  Lookit ... Fender thought THAT was needed, but never thought to add a bleed down resistor on the power supply till... mid 70's.  Thats now critical Leo thought it was (rightly so).

NEVER run a tube amp into a high impedance.  Its about as close as it gets to instant karma.
 
G

guitlouie

Guest
I don't know much about the technical aspect of all this, but I thought that not running your tube amp without speakers was like the E chord, just something that every guitar player knew!
 

WarmothRules

Senior member
Messages
313
guitlouie said:
I don't know much about the technical aspect of all this, but I thought that not running your tube amp without speakers was like the E chord, just something that every guitar player knew!

Well I guess I'm plain retarted then. I do lick windows on the short bus
 
N

neilium

Guest
WarmothRules said:
Well I guess I'm plain retarted then. I do lick windows on the short bus

Hey, better to find out this way. I found out by destroying an absolutely wonderful Magnatone amp 25 years ago. sound, sound, no sound, weird smell, puddle of hot wax in bottom of amp cabinet, depressed neilium
 
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