Hi everybody

I am hoping someone out there can help me.

I run a recording studio in Ipswich, Suffolk. I built it from scratch just over a year ago. Having never done any DIY at all I think we did a pretty good job but now after living with it for a year there are some things I wish we had done at the time.

I want to be able to keep all my amp heads (about 7 or 8) in my control room so the guitarists can plug in directly and we can adjust all the settings there and then running through the wall to the live room where the cabs live.
I am hoping to have an 8 input box on the control room side with all amps always plugged in and then an 8 output box on the live room side (all labelled accordingly to each head) so I can patch heads to cabs at will.

The reason I am confused and want some advice is my concerns about ohmage loads etc and what type of cable in the wall I would need and connectors etc.

If anyone can please help or offer some advice I would be eternally grateful as part of my decision to do this is based on my needing quite invasive surgery on my spine that means I just can not carry mesa and marshall heads from room to room anymore.

Thanks Forum friends

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You and I are mortal but rock and roll will never die!!!

Don't take this as professional advice. Hopefully someone else can confirm if my reasoning is correct.

I would install a patch bay wired with speaker wire between the live room and control room with enough jacks for each cab, or however many cabs you might want to patch in and out of quickly. In the control room, I would run the speaker output from each amp to the same patch bay which continues through to the live room. That way, you could switch cabs and heads quickly.

Assuming two rows of jacks in the control room bay, I would make the top row amp head speaker out and the bottom row guitar input. That way, you could quickly check that the amp you're using is connected to speakers. Too bad the amp standby switches could be placed right below! Might not be so simple (1:1 input-output) if any of the heads have stereo output.

A bit more follow-up.

Mismatched speaker and output transformer load should not cause any damage to your tube amps. It will just sound different than properly matched amps and speakers, usually a bit more "dull".

My main concern would be plugging into an amp, cranking it up, putting it off standby, then discovering that it's not plugged into a speaker. Hence, my recommended patching scheme.

Quote darrylonguitar:

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Mismatched speaker and output transformer load should not cause any damage to your tube amps.

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Speaking as someone who's 70's Orange Graphic 120 went 'BANG' big style due to a mismatched speaker load...



... I'll happily call you on that claim. It's bollocks. Yes, in certain circumstances you can 'get away with it' and in other circumstances you have a bigger margin of error. But the bottom line is that you are guilty of giving, at best, poor advice and, at worst, wrong advice. But if you are 100% confident that it really shouldn't cause any damage and are prepared to indemnify anyone taking your advice, I am perfectly happy to send you an invoice.

Andy

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When the going gets weird, the Weird turn Pro.

And to help the OP...

Radial Engineering make something that might go a long way to achieving what you want, but with 6 amps. You can check out the JX44 here and see if it does what you need.

Andy

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When the going gets weird, the Weird turn Pro.

Hi Danny, welcome to Bedlam!

Big ask mate and very, very fraught. Andy(zen)is bang on the money, do not mismatch amps and speakers. As he says, you will "get away" with it a lot of the time but one day, FLASH!

Next, are all the amps valve op staged? If some are solid state then run those on a different connector. Jacks say for valves and speakons for transistor. Why? Because a "fairly" safe option is to have the "cab end" jacks wired to normally short, then if someone fires up a 100watter with no speaker on tother end there will be no sound and valves can tolerate a short for a good while,(will get red!) an open circuit can be curtains in mSecs. BUT! The exact opposite applies to solid state (but I would still wire 100R at 10W resistors across the amps at some point, sstate amps, especially the crude ones in gitamps can go unstable with no load. SEE!I said it wasn't easy!).

To add to your troubles, some amps have multiple jacks at 4.8.16 Ohms, some have just one or two and an impedance selector switch, think on! Then IF you do this , get a nominated person clued up to do the pluggeratin' FCS do not let some hairy, sweaty guiatrist type cluck about with an amp patchbay (in fact I would have a lockable cabinet for the terminations).

Andy, at first sight that Radial box does not seem apt for speaker levels? I am probably wrong, will study it up.
Dave.

Because of the danger of losing an amp if things are connected incorrectly, I'd keep it as simple as you can. If it were me, I'd get three or four quality speaker cables in different colours and just run them through the wall. Then just use however many I needed at one time. Even if you have an elegant patching solution you still have to get up and physically check the connection in the live room every time you turn an amp on just to be sure. You can get away with about 10m of speaker cable although as short as possible seems sensible.

J

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www.jackruston.com

Quote Jack Ruston:

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Because of the danger of losing an amp if things are connected incorrectly, I'd keep it as simple as you can. If it were me, I'd get three or four quality speaker cables in different colours and just run them through the wall. Then just use however many I needed at one time. Even if you have an elegant patching solution you still have to get up and physically check the connection in the live room every time you turn an amp on just to be sure. You can get away with about 10m of speaker cable although as short as possible seems sensible.

J

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Tend to agree Jack except about speaker cable lengths. Valve guitar amps rarely have an op Z lower than 10Ohms and often 5 or 6 times that so even 50mtrs of 6 amp "garden orange" will make little difference. Worse case(?)100watts into 4 Ohms is only 5 amps and that only transitory.

Dave.

Quote Jack Ruston:

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Because of the danger of losing an amp if things are connected incorrectly, I'd keep it as simple as you can. If it were me, I'd get three or four quality speaker cables in different colours and just run them through the wall. Then just use however many I needed at one time. Even if you have an elegant patching solution you still have to get up and physically check the connection in the live room every time you turn an amp on just to be sure. You can get away with about 10m of speaker cable although as short as possible seems sensible.

J

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I'm with that man. Although I would try and find some sort of manual labelling method/process to avoid firing up and amp that wasn't connected to a speaker. Scares me that, don't want my nice valve amps going pop.

Alternatively on a much smaller scale (and more wallet friendly) to the JX44 you could consider a couple of these:

http://www.tonebone.com/tb-headbone-vt.htm

Not going to give you ultimate flexibility but, will hopefully avoid any impedance mismatching as you can only connect 2 heads to 1 speaker so you ensure the 2 connected are the same load as the speaker. would save on mic'ing time too, and they are buffered so you don't run the risk or having your valve amp on but with no speaker attached.

2 of them would provide 2 inputs to 4 heads to 2 cabinets.

Just a thought

Jack is right, keep it as simple as possible. A patchbay is a time consuming item to build and maintain. Leads are not. I ran 3 lengthy ones to my iso booth for the same purpose. Just hook up like any other amp. Easy times!

Quote zoosound:

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Jack is right, keep it as simple as possible. A patchbay is a time consuming item to build and maintain. Leads are not. I ran 3 lengthy ones to my iso booth for the same purpose. Just hook up like any other amp. Easy times!

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Bit boring tho' Zoo? Be nice to see a cool, well legended patch panel not seen in many studios?

I DID say it was fraught but with care in use and good basic understanding, quite possible.

Dave.

Thanks for all the advice so far. Here is an (very crude) image of what I hope to achieve (I havent added an image before so I hope this works.

Are there people/companies out there who could do this sort of thing for me (obviously paid)?

Danny



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You and I are mortal but rock and roll will never die!!!

Actually you really don't have very much of a danger to the amps from a missplug there.

Running a 16R out into an 8R cab is "wrong" but I doubt any of those heads would protest, you would theoretically shorten valve life. 8 out into 16R is a bit naughtier but again, any 1/2 decent valve amp would cope but of course use the correct Z to Z as a rule. Four into 16 is the real killer.

What is the problem with making the box? The whole thing would go into a deep 13amp double box with a blank faceplate (if you don't have a drillpress get an engineer to drill the stainless steel plates. I wanted aluminium but could find none).
The wiring is simply pin to pin, box to box and as I said, wire a short across the jack switch on the cab end box.
Some of these: http://cpc.farnell.com/cliff-electronic-components/cl1160a/6-35mm-jack-soc ket-mono-solder/dp/CN00002 I assume a metal plate in which case you want the jacks to be insulated from it, don't want to tie all those amp earths together.

Dave.

Edited by ef37a (14/07/12 10:58 PM)

Quote zenguitar:

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Quote darrylonguitar:

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Mismatched speaker and output transformer load should not cause any damage to your tube amps.

---

Speaking as someone who's 70's Orange Graphic 120 went 'BANG' big style due to a mismatched speaker load...



... I'll happily call you on that claim. It's bollocks. Yes, in certain circumstances you can 'get away with it' and in other circumstances you have a bigger margin of error. But the bottom line is that you are guilty of giving, at best, poor advice and, at worst, wrong advice. But if you are 100% confident that it really shouldn't cause any damage and are prepared to indemnify anyone taking your advice, I am perfectly happy to send you an invoice.

Andy

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Sorry to pass on possibly bad advice and to hear about the Orange. After a little more digging, I think the advice regarding impedance mismatch may have been specific to my gear when first told to me. I have all fairly low power tube amps between 5 - 20 watts with 4- and 8-ohm impedances. After a bit of further reading, it appears that impedance mismatch may not be an issue for quality low-power amps and up to 2:1 mismatches.

I did say to take my advice on the particular issue with a hefty grain of salt at the beginning hoping that others with more experience could chime in. Guess that mission is accomplished.

Fine Darrly.

You are pretty much on the money, when it comes to amp damage size matters! For damage to occur two conditions must obtain.

A seriously mismatched* load, 2:1 or worse.
A drive signal of sufficient amplitude to generate damaging voltages. It is in fact perfectly "safe" to leave a 100W valve amp completely unloaded SO LONG AS THERE IS NO DRIVE SIGNAL. But even the residual noise in many amps could be enough if the pots were well advanced.

*Matching, as many here will know is the wrong term, we never "match" power amplifiers to their loads but I cannot think of a better term and so will bow to the general usage in this matter.

Dave.

That's OK Darrylonguitar,

It is to your credit that you looked into things more and then had the balls to come back and revise your opinion so publicly. Thank you. And welcome to SOS forms

Andy

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When the going gets weird, the Weird turn Pro.

Where will the guitarist be?