XLR Out For Tube Amp?

[Rustic]

Hello Everyone,

I'm new to tube amps but have started checking them out. The solid state amps I've used all have an XLR out to go to the board. Tube amps seem to either not have an out, or have only a 1/4" jack out. I realize that generally tube amps are recorded (or sent to the house) with mics. What is going on here that makes this the case?

Thanks for any insights.

[jazzbow]

Hello Everyone,

I'm new to tube amps but have started checking them out. The solid state amps I've used all have an XLR out to go to the board. Tube amps seem to either not have an out, or have only a 1/4" jack out. I realize that generally tube amps are recorded (or sent to the house) with mics. What is going on here that makes this the case?

Thanks for any insights.

It's just down to the design, All amps could have XLR outs.

Check the link,

Products - TubeMeister 18 Head - Hughes & Kettner

[jazzbow]

Here's another but it has been dropped by peavey.

Peavey :: Windsor Studio

It seems that manufacturers have noted that a lot of guitarists are recording digitally so these smaller wattage amps are produced for studio recording.

[robertm2000]

If the amp has a line level out could you use a direct box to convert it to mic level and impedance for a PA?

[jazzbow]

Yep, click the link.
Hughes and Kettner Red Box are one of the best DI boxes.

Products - Red Box Classic - Hughes & Kettner

[cosmic gumbo]

I've had quite a few ss amps and none ever had an xlr out. I don't think it's all that common for any guitar amp.

[fep]

If the amp has a line level out could you use a direct box to convert it to mic level and impedance for a PA?

Every PA I've worked with has had inputs for both high and lo z with both xlr and 1/4" inputs (and often both 1/4 inch hi and lo z inputs).

I always thought the reason you wanted to go to low z was to keep the signal to noise ratio quiet over long runs. Which is done by putting the signal out of phase and then back into phase.

[TieDyedDevil]

Every PA I've worked with has had inputs for both high and lo z with both xlr and 1/4" inputs (and often both 1/4 inch hi and lo z inputs).

Most do.

If you're working in an environment where the mixer is off-stage, however, there'll be a stage box (or two, or more...) running only XLR lines back to the mixer. So you may not always have the option of using the 1/4" inputs.

Also, there are two kinds of 1/4" lines: balanced and unbalanced. The balanced line is pretty much electrically equivalent to an XLR; there are three terminals on the plug - referred to as TRS. The unbalanced line has only two terminal - referred to as TS.

1/4" jacks all look the same from the outside. There's no way to know whether you have a balanced or unbalanced connection without a label or a schematic.

I always thought the reason you wanted to go to low z was to keep the signal to noise ratio quiet over long runs. Which is done by putting the signal out of phase and then back into phase.

The noise reduction comes partly from the low impedance and partly from sending an out-of-phase signal physically adjacent to the in-phase signal. Any electrical noise from the environment will be cancelled out because it affects the in-phase and out-of-phase signal equally.

[Funkwire]

My Egnater Rebel 30 amp has an XLR out. I use it all the time when we're running our own sound. When the club provides a soundman, they always decline to use it and stick a mic in front of the amp.

I think it sounds great. It's voiced pretty flat, so I like to brighten the signal up just a bit. But that's it.

[obinGilchrist]

All amps could have XLR outs

[Strickland]

I think most players who like the tone of a tube amp, like the sound that results from the interaction of the power amp section, the pre amp section, and the speaker. We aren't the types to be happy sending a pre amp sound to a board. Solid state is going to sound the same no matter what.

[JohnStrebeck]

Most guitar players like the interaction of the tubes with the tonal settings on the amp. Therefore, most tube amps do not have an XLR input as it (essentially) takes the sound directly from the guitar to the board. Because of this, you don’t always get the interaction with the tubes and the difference when you play softly as opposed to when you strum louder. You would do much better tone wise by micing the amp with an appropriate microphone and then sending the mic into the sound board. However, this does limit the amount of work the engineers can do sound level-wise. Though this does allow guitar players to have more control over the level of the amp as well as tone.Hope this helps.

[Cunamara]

Also, there are two kinds of 1/4" lines: balanced and unbalanced. The balanced line is pretty much electrically equivalent to an XLR; there are three terminals on the plug - referred to as TRS. The unbalanced line has only two terminal - referred to as TS.

1/4" jacks all look the same from the outside. There's no way to know whether you have a balanced or unbalanced connection without a label or a schematic.

TS and TRS jacks don't look the same.

[BeBob]

Hello Everyone,

I'm new to tube amps but have started checking them out. The solid state amps I've used all have an XLR out to go to the board. Tube amps seem to either not have an out, or have only a 1/4" jack out. I realize that generally tube amps are recorded (or sent to the house) with mics. What is going on here that makes this the case?

Thanks for any insights.

It's an optional feature that requires significant cost to implement. It shouldn't be any surprise that most amps don't have it because it's a feature that's not in demand.

The Red Knob Twin had an output transformer that was unlike other tube amps -- it had a special secondary winding to produce the BLO sent to the XLR jack.

The SVT2 Pro had an additional balanced line transformer that took the preamp signal and provided a BLO sent to the XLR jack.

Special purpose transformers cost money. Rather than adding to the price of the amp to provide a feature that is not in demand, amp companies usually skip them on anything that's not a high end model.

[feet]

not sure if the guy is still curious some seven years later, but i have two tube amps with xlr outs. well, a pre amp and a power amp- old peavey rack stuff. and they both work fine, i guess. about what you would expect. really need an ir or something for it, though. the straight xlr out doesn't work any better without a speaker or a cab coming from a tube amp than it would from a solid state one. but with a decent cab emulation, it sounds about the same as it would through an amp.

part of me understands why you don't see it that often, but i suspect the concept is making or will make a comeback now, in the age of home recording and lunch box amps and emulators and digital everything. i think some new high gain amps have it. and of course, now we have load boxes and such which are essentially the same thing, but with more options.

[sgosnell]

All 1/4" jacks that I've ever seen look the same from the outside. You have to be able to see the contacts inside to know whether it's stereo or not, and I've seen lots of guitars and amps with TRS jacks that are only used for TS applications, probably because it's often cheaper and easier to use the same jacks for everything. You cannot tell by looking at an installed jack from outside.

[Endorphins]

Red Box is what I use.









.

[icr]

In my opinion a tube amp sounds better when connected to a speaker and microphone. If you do want to run your tube amp direct, there are many products on the market you can use that will correct the impedance mismatch and give you an XLR line-out.

[rickjazzmister]

I am assuming historically many players were not going to like a XLR direct because a direct signal without some sort of power amp or speaker emulation sounds like crap, Mesa, Engl and others build tube amps with direct outs that contain some sort of speaker emulation or EQ to help. Now with the plethora of hardware (Two-Notes) and software cab modeling software and XLR out on a tube amp provide value.

[Greentone]

_One_ reason that tube amp designers don't put XLR outs on their amps is that users might be tempted to use the amps without speakers connected because they are going direct to the board/PA. The problem with using a tube amp without speakers, of course, is that the output transformer (OT) has no load--it senses a load, rather, of infinite impedance, which is reflected back to the power tubes. The amp attempts to power this "load" by ramping up the voltage to the point where the OT and/or the tubes self-destruct. YOU SHOULD ALWAYS OPERATE A TUBE AMP INTO AN APPROPRIATE IMPEDANCE LOAD, I.E., INTO A SPEAKER.

With solid-state amps, however, it's okay in general, to turn on the amp without a speaker connected. Just using the amp head as a signal source for the XLR-out will work. (Do look at your operating manual, however, to confirm this.)

[rickjazzmister]

_One_ reason that tube amp designers don't put XLR outs on their amps is that users might be tempted to use the amps without speakers connected because they are going direct to the board/PA. The problem with using a tube amp without speakers, of course, is that the output transformer (OT) has no load--it senses a load, rather, of infinite impedance, which is reflected back to the power tubes. The amp attempts to power this "load" by ramping up the voltage to the point where the OT and/or the tubes self-destruct. YOU SHOULD ALWAYS OPERATE A TUBE AMP INTO AN APPROPRIATE IMPEDANCE LOAD, I.E., INTO A SPEAKER.

With solid-state amps, however, it's okay in general, to turn on the amp without a speaker connected. Just using the amp head as a signal source for the XLR-out will work. (Do look at your operating manual, however, to confirm this.)

Great point, no load is a problem.

[feet]

i kinda forgot about all that. my pile of tubes is plugged into a cabinet at all times, even when i play with the xlr outs. honestly, it's kinda nice in that you don't lose any of the playing feel or nuance because nothing has changed. and you could still involve a mic, if you'd like. i just run the xlr into a preamp and then into the interface.

having read this last night, i was kinda fantasizing about putting my big amps and cabs in storage and just keeping the little guys out and using the xlr out. i forgot that was a really bad idea.

i did consider picking up a load box at one time (the suhr, most likely) but i was able to escape when i realized i had some xlr options. no such luck for my voxes, so maybe there is a load box in my future one day? i am looking to relocate and downsize but the 4 watts of doom is still way too loud for apartment use if i'm not careful.

[BComp61]

As noted above, depends on the amp. Like Mesa and Engl previously mentioned, Egnater Rebel 30 amps have a "Silent Record" switch that allows you to go to straight to the board either live or in studio and bypass the speaker cab.
"Egnater’s innovative and natural sounding direct record output delivers every ounce of Rebel-30 Mark II all-tube tone without the need of a microphone or speaker. The balanced XLR output is wired after the power amp so every control including the tube mix, wattage control, plus tight and bright switches are always engaged. Use this XLR output to replace microphones during live stage use or set to Silent mode and record at full power in your bedroom or studio..." These amps are REALLY versatile, IMHO.

[BeBob]

As a matter of electronics, there's only one way to get a native BALANCED output out of a conventional amplifier's output section, and that's to construct a special purpose coil on the output transformer as Fender did in the Red Knob Twin, or to take it from the phase inverter as in the Loud/Ampeg designs. Another method, which is actually a cheat, is to take a single-ended signal and run it through opamps to create a balanced signal. Doing this violates any claims that an amp maker may make about "all tube tone."

Reading that quote from Egnater gave me pause. I didn't believe what it said, so I looked online for a schematic for the Egnater Rebel 30. Here is what I found:



Looking at the schematic I can't see a balanced line output being tapped on the output transformer. There is a single-ended connector on the OT secondary and a similar looking connector at the phase inverter. These connectors are likely the connectors for the NFB loop. A similar looking connector takes a single-ended output and then splits it into a balanced line driver using opamps. It is not clear from the low-res schematic where the balanced line drive gets it's input. What I can tell is that by looking at the schematic, this amp does not seem to have a balanced XLR output being taken after the power amp. What it does appear to have is an driver circuit composed of ICs that takes a single-ended input signal and uses solid state electronics to convert it to balanced line drive. Looking at the schematic I can't verify that there is any balanced signal being taken after the power amp. What I see is a solid state circuit that converts an unbalanced signal to a balanced signal connecting to the XLR jack. So much for the claims about "all tube tone."

Of course this doesn't mean that the amp sounds bad, only that some of the claims might be inaccurate.

[BComp61]

I'm not a tech guy nor an engineer, but all I know is that whatever they do, it sounds great - and tube ampish - going through their XLR out. I used it in a live setting for over 2 years which I wouldn't have done if it sounded bad or "faux tube". Just my 2 cents! YMMV