Why Won't My "Y" Box Work With Two Amps?

LPV

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So the speakers don't go thru the y box? or when you do use the y box for the speakers you are only running one head ? As far as in front of the amp I'd still try lifting the ground on one of the amps.
 

Torren61

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You are correct. The speakers only go through the Y box when I use one head so I can parallel the speakers and bring the Ohms down to 8 from 16.

When you say "lift the ground", I don't get it. Lift it at which point in the amp?

Thanks for the advice, btw.
 

LPV

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Pick one of these up at the hardware store. Just don't touch the metal tab to the screw that holds on the plastic cover of your outlet. Or break off that little tab. I "think" that as long as one of the amps are grounded the current will go back thru your y box to the other cable and to its ground in the unhappy coincidence that there is a nuclear meltdown inside of one of your amps at the exact same time you are trying this. Not sure tho. Anyway its a very common practice when using two amps that aren't isolated with a high end power conditioner or something else. DO NOT use it on only one amp WITHOUT YOUR Y box tho!

groundlift.jpg
 

tolm

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Okay, here's a question:

So you run one amp, put the speakers in parallel and that gives you an 8ohm load for the single amp. Got that.

But when running both amps, each amp is hooked up to a single speaker only? That means each speaker is 16 ohms but the amps are 8ohms. Not sure if that would cause a 'hum' but it's certainly not good.
 

tolm

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Pick one of these up at the hardware store. Just don't touch the metal tab to the screw that holds on the plastic cover of your outlet. Or break off that little tab. I "think" that as long as one of the amps are grounded the current will go back thru your y box to the other cable and to its ground in the unhappy coincidence that there is a nuclear meltdown inside of one of your amps at the exact same time you are trying this. Not sure tho. Anyway its a very common practice when using two amps that aren't isolated with a high end power conditioner or something else. DO NOT use it on only one amp WITHOUT YOUR Y box tho!

groundlift.jpg

And for God's sake don't go near any mics - this can be very dangerous. Personally, I wouldn't take the ground of anything that isn't double-insulated and certainly not valve amplifiers ...

Please be careful!!
 

Torren61

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Thanks for the info. The Lehle sounds like the solution. 16 ohm should be okay. Never had a problem with hum before with the single speaker.
 

LPV

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And for God's sake don't go near any mics - this can be very dangerous. Personally, I wouldn't take the ground of anything that isn't double-insulated and certainly not valve amplifiers ...

Please be careful!!

Like I said, I'm not sure about that advice either. I just know many people do it. But buying a proper box is definitely the best and safest route :thumb:
 

Colabrador

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From what I can see, your output box should be okay..except you must keep an eye on the contact points in the phone jacks.. they will burn over time at output current levels. Your problem is on the input side. IMHO your are on the right track but it's not as easy as building a Y network for the input...the science will tell you that you have built a radio antenae and hooked it up to the inputs. Please see my post in this forum titled "My Dream Rig Lives" I am running four channels of input and had to solve this exact problem. What you need on the input side is what we call the F-Tube. Gotta go to work.. will check on you this evening.

Todd
 

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