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Studio Guitar Amps - Wiring Effects Pedals, Units & Accessories
Old 20th December 2010
  #1
Gear Maniac
 

Studio Guitar Amps - Wiring

I have a lot of amps and a few cabs in the studio - is there an easy/affordable solution that would allow me to have them all wired at once and be able to select which cab to route to? Right now I have to get behind each amp every time I want to switch heads/cabs. And that involves recording with one amp, letting tubes cool down, unplug, plug into new head, warm tubes, turn on, record. Kind of a PITA! Any solutions would be rad!

Also, while you're here - if you have any suggestions on a splitter box that would allow me to run the same signal to 2 amps at once, that would be rad too. Did this on a record I did in a larger facility, but I don't personally own a box at my place that would do this.

Thanks all!
Old 20th December 2010
  #2
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The dman's Avatar
 

Quote:
Originally Posted by destiny brandon View Post
I have a lot of amps and a few cabs in the studio - is there an easy/affordable solution that would allow me to have them all wired at once and be able to select which cab to route to? Right now I have to get behind each amp every time I want to switch heads/cabs. And that involves recording with one amp, letting tubes cool down, unplug, plug into new head, warm tubes, turn on, record. Kind of a PITA! Any solutions would be rad!

Also, while you're here - if you have any suggestions on a splitter box that would allow me to run the same signal to 2 amps at once, that would be rad too. Did this on a record I did in a larger facility, but I don't personally own a box at my place that would do this.

Thanks all!
Ampeg makes one that you can usually find on ebay fairly cheap, I think I paid $40 for mine. It has 2 tube amp inputs and 6 solid state which can be changed for tube amps with a resistor I belive

Ampeg System Selector 8 amps in 8 speakers out - Guitar amplifier bazaar world
Old 20th December 2010
  #3
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andychamp's Avatar
Quote:
Originally Posted by destiny brandon View Post
(...) Right now I have to get behind each amp every time I want to switch heads/cabs. And that involves recording with one amp, letting tubes cool down, unplug, plug into new head, warm tubes, turn on, record. Kind of a PITA!(...)
Can't you just leave the unused amps on "standby"?
Old 20th December 2010
  #4
Gear Addict
 
Bob Vinsick's Avatar
Although I don't know of any device, I'm sure this can be done by any person that knows electronics. The problem comes in when you are pushing large wattage that switches won't be able to handle the power, so relays would work better or maybe rotary switchs would be easier to design and build.

You need two mains circuits; one to switch the head and the other to switch the cabinet. If relays are used, you will need a relay for each cabinet and a relay for each amp. The circuit would be easy to build. The good thing is you aren't switching line level or mic/guitar level signals so noise won't be a big factor.

If a rotary switch is used, it will be easier and less expensive to design and build, although I would build it with relays probably. I'm sure this can be done pretty easily.
Old 20th December 2010
  #5
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AudioWonderland's Avatar
 

Quote:
Originally Posted by destiny brandon View Post
I have a lot of amps and a few cabs in the studio - is there an easy/affordable solution that would allow me to have them all wired at once and be able to select which cab to route to? Right now I have to get behind each amp every time I want to switch heads/cabs. And that involves recording with one amp, letting tubes cool down, unplug, plug into new head, warm tubes, turn on, record. Kind of a PITA! Any solutions would be rad!

Also, while you're here - if you have any suggestions on a splitter box that would allow me to run the same signal to 2 amps at once, that would be rad too. Did this on a record I did in a larger facility, but I don't personally own a box at my place that would do this.

Thanks all!
Why are you waiting for the tubes to cool? Once the power is off its off.
Old 20th December 2010
  #6
Gear Head
 

I know that it can be done. My amp tech has his entire shop wired so you can bring in your favorite amp head and demo all of his different cabs and speakers. I'd start looking at Lehle Gitarrentechnik PURE SOUND - NO NOISE - MORE TONE. If they don't have what you are looking for, talk to my amp tech at South Valley Vintage Amps.
Old 20th December 2010
  #7
Lives for gear
You have 3 questions really:

1. For the amp/cabinet switcher, the Ampeg ones work well. Mine keeps a steady 4 ohm load on the heads whether they're plugged into a cab or not. In theory, I could leave them turned on and just switch cabinets. In practice, I don't trust it that well, so I put each amp on standby when I switch. When on standby, there's no current flowing thru the output transformer, so it doesn't hurt to unplug the head completely. Which bring us to question 2:

2. If the amp head is on standby, you can unplug and replug cabs to your hearts content. You can have every head in the studio on standby and just switch cabs if you want. For the most down and dirty way to make this work, build a cable with a 1/4" jack on one end and a female 1/4" connector on the other. Plug it into the cab and drape over the front of the cab so it's easy to access. Each head then has it's own cable with 2 1/4" male ends. Simply mate the head to the cab "speaker cables" and switch on...

3. You can easily split a guitar signal to more than one amp using any number of splitters. You'd like to keep the impedance the guitar sees high to preserve high end, so you need a solution that isolates the amps, not just an ABY box. Transformer balanced switchers like the Radial Switchbone have the least likelihood of ground loop hum...
Old 20th December 2010
  #8
Old 20th December 2010
  #9
Gear Maniac
 
Soundgeeza's Avatar
 

In an emergency situation at Sonisphere in Knebworth last year, whilst Teching for Airbourne, I wired these puppies up using NINE Boss TU-2 Tuners daisy chained together.

That's six stacks per side and YES they are ALL running (and loud!)

Worked a bloomin' treat .... with NO HUM!

The guys from Marshall were pissing themselves... didn't think it could be done!

There's one for the 'Roadie 101' manual!

Old 20th December 2010
  #10
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NeedsMoreFuzz's Avatar
 

Quote:
Originally Posted by Soundgeeza View Post
In an emergency situation at Sonisphere in Knebworth last year, whilst Teching for Airbourne, I wired these puppies up using NINE Boss TU-2 Tuners daisy chained together.

That's six stacks per side and YES they are ALL running (and loud!)

Worked a bloomin' treat .... with NO HUM!

The guys from Marshall were pissing themselves... didn't think it could be done!

There's one for the 'Roadie 101' manual!

That's a stroke of genius actually --- I don't think I'd have thought of that (although I very rarely have nine TU-2's lying around lol) --- def one to remember.
Old 20th December 2010
  #11
Old 20th December 2010
  #12
Gear Maniac
 

Quote:
Originally Posted by Soundgeeza View Post
In an emergency situation at Sonisphere in Knebworth last year, whilst Teching for Airbourne, I wired these puppies up using NINE Boss TU-2 Tuners daisy chained together.

That's six stacks per side and YES they are ALL running (and loud!)

Worked a bloomin' treat .... with NO HUM!

The guys from Marshall were pissing themselves... didn't think it could be done!

There's one for the 'Roadie 101' manual!

UNREAL!!!
Old 20th December 2010
  #13
Gear Maniac
 

Quote:
Originally Posted by andychamp View Post
Can't you just leave the unused amps on "standby"?
I've heard both sides of this. Some have told me it doesn't matter until the amp is switched fully on. But others have told me that it is bad on the amp to NOT have it plugged into a cab, even when on "standby" mode.

I think I may have even asked this question on a thread here on GS a few years back.

Can anyone confirm this?
Old 20th December 2010
  #14
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guitarwolle's Avatar
Patchbay works

I had the same problem, I use 3 heads and 7 cabs - only in the studio.

To run head simultanously I use Lehle Dual SGoS and my old Boss Chorus Ensemble. That gives me 3 outs. As far as I know you can olso use the Lehle tuner out to an amp.

For the cabs I'm right now in the process of putting together a patchbay. I bought an old 40 input patchbay (1/4" jacks), old German handmade stuff, very very heavy. It really needs some force to plug in the jacks.

I've wired cab outs for 5 amps (just in case) to the patchbay and doubled them (parallel), so it uses 10 outputs. When no cable to a cab on the patchbay is connected, the circuit is short-cut. That way you dont have to switch amps off or to standby. When using tube amps, that works just fine. You could aswll use resistors with sufficient watts in lieu of short-cutting. With my layout, dont use tranistor amps, they will die.

Attached is a copy of my layout, showing what can be connected. The parallel ans series area is just in case i want to connect more than 2 cabs to one amp, they aswell are designed to short-cut the circuit once the cab is disconnected, so the amp is never at risk.
Attached Files
File Type: pdf Patchbay Layout Gitarrenboxen.pdf (16.7 KB, 294 views)
Old 20th December 2010
  #15
One with big hooves
 
Jay Kahrs's Avatar
Quote:
Originally Posted by destiny brandon View Post
I've heard both sides of this. Some have told me it doesn't matter until the amp is switched fully on. But others have told me that it is bad on the amp to NOT have it plugged into a cab, even when on "standby" mode.

I think I may have even asked this question on a thread here on GS a few years back.

Can anyone confirm this?

I'll both confirm AND deny that.

The truth is that it depends on the amp and really, the output transformer and health of said transformer.

Some amps can withstand that sort of abuse, being plugged in without a load and nothing will happen. With some amps (most) its a death sentence... sometimes instant, sometimes gradual. At best it burns up a set of output tubes.

In general, don't ever use a tube head without a proper load...
Old 20th December 2010
  #16
Gear Maniac
 
Soundgeeza's Avatar
 

If the original poster is referring to being able to NOT have a speaker connected whilst in standby mode, then as far as I'm aware, you should be OK.

As the poster above states, you should NEVER switch a (valve/tube) amp on without a load ... ie flick the standby switch so that your amp is fully on.

One caveat to leaving amps on standby without a cab/load connected ... I can guarantee that at somepoint, SOMEONE will flick that switch without realising and you'll check your tuner on mute ... volume control and guitar and everything before the penny drops!

Not a recommended approach, but as far as I know, most amps are OK if in standby.
Old 21st December 2010
  #17
Lives for gear
OK the basic physics behind NOT having a guitar amp turned on and operating into an open short (nothing plugged into a Marshall amp, for example) is that the back EMF when the magnetic field reverses can cause a surge thru the OT that's big enough to fry wiring. Fender prevents this by having a shorting jack (closed short when nothing's plugged in, 0 ohms) which works great if you're just unplugging your BF Bassman but won't help if you're moving the cable from speaker cab to speaker cab. Be that as it may, I can absolutely guarantee you that with the amp on standby, there is no voltage to the plates of the output tubes and there for no output to create said back EMF and there for no problem with having an open short in the output circuit. As someone mentioned, though, it's really easy to forget to have a head plugged into something when you switch it on and play a loud note or two before you realize something's wrong, so not a good idea in a studio. But definitely no harm to any tube amp to be on standby with no speaker cab...
Old 21st December 2010
  #18
Gear Guru
 
kafka's Avatar
Quote:
Originally Posted by drbob1 View Post
I can absolutely guarantee you that with the amp on standby, there is no voltage to the plates of the output tubes and there for no output to create said back EMF and there for no problem with having an open short in the output circuit.
+1 drbob1 speaks the truth.

Quote:
Originally Posted by drbob1 View Post
As someone mentioned, though, it's really easy to forget to have a head plugged into something when you switch it on and play a loud note or two before you realize something's wrong, so not a good idea in a studio. But definitely no harm to any tube amp to be on standby with no speaker cab...
And this is also the truth.

So basically, it's a passable idea, right up until the moment somebody f**ks up and forgets to put it in standby first.

(ok, well, actually, sometimes you can even get away with this, too, as long as no sound is coming out of the amp. But in the end, this f**k up is just one degree of separation from the above f**k up.)
Old 21st December 2010
  #19
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andychamp's Avatar
Some modern tube amps (like Engl) don't come with a standby switch. Instead, they have a special protection circuit to prevent frying the output transformer. But when this is the case, the manual should say so.
I've seen some older amps w/o standby switch, too. Can't remember the name right now, but I wouldn't be so sure about any tricky protection circuits.
Old 21st December 2010
  #20
Lives for gear
The standby switch is there to allow the heaters of the tubes to get up to temperature, so that when you apply a signal, electrons are happily jumping off the cathode. If you try and run a tube with a cold cathode, in theory, it could strip off the coating that releases the electrons.

Amps without standby switched, like the Vox AC30, generally have an indirectly heated cathode in the rectifier. So, when the amp switches on, there's no B+ (plate high voltage) available till after the rectifier has warmed up, by which time the power tubes have also warmed up.

In that case you are flirting with disaster not having a speaker cab attached before turning it on...
Old 21st December 2010
  #21
Gear Maniac
 
Soundgeeza's Avatar
 

Quote:
Originally Posted by NeedsMoreFuzz View Post
That's a stroke of genius actually --- I don't think I'd have thought of that (although I very rarely have nine TU-2's lying around lol) --- def one to remember.
Admittedly, we did have to buy another 5 from the Tour Supply backstage shop!

That was one of the hairiest shows I've ever done ... 45 minute change-over ... 12 Marshall Stacks ... 2 Ampeg 8x10 rigs and NINE Boss tuners! ...

I earned my money that day I can tell you!

I must also state that Airbourne are perhaps the nicest guys that I've ever worked with and they are always very appreciative of the crew.

(sorry for going OT)
Old 22nd December 2010
  #22
Gear Maniac
 

Quote:
Originally Posted by Jay Kahrs View Post
I'll both confirm AND deny that.

The truth is that it depends on the amp and really, the output transformer and health of said transformer.

Some amps can withstand that sort of abuse, being plugged in without a load and nothing will happen. With some amps (most) its a death sentence... sometimes instant, sometimes gradual. At best it burns up a set of output tubes.

In general, don't ever use a tube head without a proper load...
are you referring to amps being fully ON or in STANDBY mode with this post?

still getting conflicting answers regarding turning an amp on to standby mode without being connected to a cab. although more people have replied stating that it will not hurt the amp to do so.
Old 22nd December 2010
  #23
Lives for gear
 

Quote:
Originally Posted by destiny brandon View Post
are you referring to amps being fully ON or in STANDBY mode with this post?

still getting conflicting answers regarding turning an amp on to standby mode without being connected to a cab. although more people have replied stating that it will not hurt the amp to do so.
What IS potentially harmful is the amplifier attempting to send current to a speaker load without any such load being connected. Depending on how robust the amp's output transformer is, it may be able to withstand a certain degree of such punishment, or it may fail right away. There should not be any potential for damage if an amplifier is on standby (or even completely engaged) IF you can guarantee that the amplifier isn't going to try passing any sound. I've never owned an amp that made any noise at all through the speaker when it was on standby, though I'd stop short at saying such a situation couldn't happen. Long story short: as long as you are confident your amp isn't going to try to make sound while it's on standby, you're fine to disconnect the speaker without shutting the power off. I do it all the time.
Old 22nd December 2010
  #24
One with big hooves
 
Jay Kahrs's Avatar
Quote:
Originally Posted by destiny brandon View Post
are you referring to amps being fully ON or in STANDBY mode with this post?
Either.

I know a guy who burned up a '77 Marshall JMP by leaving it on standby for a several hours "to keep it warm" in a studio without a cab connected and there was no signal when he wanted to use it. Not even a blip.

Toasted the output transformer, power tubes, bridge rectifier... bunch of stuff.

Damage to the amp is either going to be very gradual... ie; hard to notice or all at once.

If it was "safe" to power the amp without a load, even in standby... don't you think that at least one manufacturer would put that in an owners manual?

But hey, its your repair bill. Not mine. Do what you will...
Old 22nd December 2010
  #25
Gear Maniac
 

Quote:
Originally Posted by Jay Kahrs View Post
Either.

I know a guy who burned up a '77 Marshall JMP by leaving it on standby for a several hours "to keep it warm" in a studio without a cab connected and there was no signal when he wanted to use it. Not even a blip.

Toasted the output transformer, power tubes, bridge rectifier... bunch of stuff.

Damage to the amp is either going to be very gradual... ie; hard to notice or all at once.

If it was "safe" to power the amp without a load, even in standby... don't you think that at least one manufacturer would put that in an owners manual?

But hey, its your repair bill. Not mine. Do what you will...
good, this is the answer i was looking for, and the practice i have always used in the studio with amps and cabs.
Old 23rd December 2010
  #26
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guitarwolle's Avatar
Quote:
Originally Posted by destiny brandon View Post
good, this is the answer i was looking for
I thought you were looking for this:

Quote:
Originally Posted by destiny brandon View Post
I have a lot of amps and a few cabs in the studio - is there an easy/affordable solution that would allow me to have them all wired at once and be able to select which cab to route to?
That’s what some of the posts referred to. If you are loocking for an answer how the standby switch of a tube amp works, please let us know right in th beginning and we dont have to write about solutions on your original question.


Quote:
Originally Posted by destiny brandon View Post
the practice i have always used in the studio with amps and cabs.
Yeah, that's exactelly the attitude preventing innovation. I mean climbing behind your cabs keeps you fit and switching off you tube amps every time keeps tube production rolling.

What do you think how great pieces of gear like the SPL Transducer work - without blowing your amp? With the Transducer you can crank your amp up fully, without a cab connected, and the Transducer will give you a mic or line level signal you can record without producing any noise at all.

The way this is done is using big resistors (see also post no 2 Ampeg System Selector, where you have to add resistors to get more tube amp ins - same trick - and a solution to your original question).

As I’m not an electronic freak, I've discussed the design of my cab patchbay with Dirk Baldringer, who I know since 25 years and who modifies most of my equipment. He is the developer for example of one Hughes & Kettner tube amp and produces the Dual Drive, a well respected overdrive pedal in Europe (which he has developed aswell). Just a few days ago he had Steve Lukther in his shop testing his stuff. I suppose he knows what he is doing.

The result of the discussions with Dirk is - either use large resistors or - even better and simpler - short cut the speaker out (only with tube amps) and NOTHING can happen to your amp. Short cutting the speaker out is according to him a factory design on some of the Fender amps - they should know!

This way I am glad not to have to climb behind my cabs and amps anymore, using my patchbay, that works great and shortcuts every speaker out of my amps when nothing is connected. I suppose I have to look for another sport ;-)

By the way, having an amp on standby without a cab connected cannot destroy the amp - unless there is something wrong with it - this is the unisono comment of the Dirk Baldringer, Ralf Reichen (developer of the transducer and of different tube amps) and van de Haar, who produces the dutch boutique amps "HOOK" (got one, great stuff).


When you have lots of amps as you say, I’m sure you have an amp tech somewhere looking after your stuff - just ask him, he will tell you.


Well then, keep on climbing !!!





p.s.
Sorry for being sarcastic, but this thread is a bit strange - you ask for a solution to your problem, which you describe as:

Quote:
Originally Posted by destiny brandon View Post
I have a lot of amps and a few cabs in the studio - is there an easy/affordable solution that would allow me to have them all wired at once and be able to select which cab to route to
And there are at least two solutions described in this thread:

1) the Ampeg System Selector and

2)the patchbay, which takes into account the needs of tub

And if you do a search at gearslutz you will find answers to exact your topic here:

Rack Mount Guitar Amp Selector?

Besides a patchbay, this thread suggests aswell the Ampeg and the Sound Sculpture Head Trip (which was unavailable for over a years or so when I was looking for solutions).
Old 23rd December 2010
  #27
Gear Maniac
 

Quote:
Originally Posted by guitarwolle View Post
I thought you were looking for this:



That’s what some of the posts referred to. If you are loocking for an answer how the standby switch of a tube amp works, please let us know right in th beginning and we dont have to write about solutions on your original question.




Yeah, that's exactelly the attitude preventing innovation. I mean climbing behind your cabs keeps you fit and switching off you tube amps every time keeps tube production rolling.

What do you think how great pieces of gear like the SPL Transducer work - without blowing your amp? With the Transducer you can crank your amp up fully, without a cab connected, and the Transducer will give you a mic or line level signal you can record without producing any noise at all.

The way this is done is using big resistors (see also post no 2 Ampeg System Selector, where you have to add resistors to get more tube amp ins - same trick - and a solution to your original question).

As I’m not an electronic freak, I've discussed the design of my cab patchbay with Dirk Baldringer, who I know since 25 years and who modifies most of my equipment. He is the developer for example of one Hughes & Kettner tube amp and produces the Dual Drive, a well respected overdrive pedal in Europe (which he has developed aswell). Just a few days ago he had Steve Lukther in his shop testing his stuff. I suppose he knows what he is doing.

The result of the discussions with Dirk is - either use large resistors or - even better and simpler - short cut the speaker out (only with tube amps) and NOTHING can happen to your amp. Short cutting the speaker out is according to him a factory design on some of the Fender amps - they should know!

This way I am glad not to have to climb behind my cabs and amps anymore, using my patchbay, that works great and shortcuts every speaker out of my amps when nothing is connected. I suppose I have to look for another sport ;-)

By the way, having an amp on standby without a cab connected cannot destroy the amp - unless there is something wrong with it - this is the unisono comment of the Dirk Baldringer, Ralf Reichen (developer of the transducer and of different tube amps) and van de Haar, who produces the dutch boutique amps "HOOK" (got one, great stuff).


When you have lots of amps as you say, I’m sure you have an amp tech somewhere looking after your stuff - just ask him, he will tell you.


Well then, keep on climbing !!!





p.s.
Sorry for being sarcastic, but this thread is a bit strange - you ask for a solution to your problem, which you describe as:



And there are at least two solutions described in this thread:

1) the Ampeg System Selector and

2)the patchbay, which takes into account the needs of tub

And if you do a search at gearslutz you will find answers to exact your topic here:

Rack Mount Guitar Amp Selector?

Besides a patchbay, this thread suggests aswell the Ampeg and the Sound Sculpture Head Trip (which was unavailable for over a years or so when I was looking for solutions).
i apologize for the confusion, when i said that was the answer i was looking for i was referring only to the answer regarding the standby vs on while plugged into speaker cab. thank you for your input!
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