Tube Amp External Speaker

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Riff Raff
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Tube Amp External Speaker

Post by Riff Raff » February 23rd, 2008, 10:07 am

I have an Epiphone Valve STANDARD, 15 watt tube combo. It has two speaker outputs in the back. One of them is being used already by the built in speaker and it is labeled "Speaker - 8 OHM". The other one is labeled "8 Ohm min". Now I know how minimum loads work with my solid state bass amp and cab (two 8 ohm cabs = 4 ohms) but I'm unclear about this amp. Can I plug in another 8 ohm cab and leave the internal speaker plugged in, or do I need to unplug the internal speaker before plugging in another 8 ohm cabinet? I looked on Epiphone's website for a user manual but it is useless.

Thanks,
Dave

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Wes Inman
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Re: Tube Amp External Speaker

Post by Wes Inman » February 23rd, 2008, 1:01 pm

Yes, it should be perfectly safe to connect another speaker or speaker cab as long as it is rated 8 ohms or more. You just don't want to connect a 4 ohm speaker or cab. Your amp will operate safely at 4 ohms total load. Anything under that can cause the amp to overheat and possibly damage it.

The Epi Valve amps in this series (I own the head version) will operate down to 4 ohms.
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Riff Raff
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Re: Tube Amp External Speaker

Post by Riff Raff » February 23rd, 2008, 1:53 pm

This is from the manual:

Epiphone Valve Standard DSP
...
Speaker: Special Design, 12”, 8 Ohms


"Speaker Outputs (Rear Panel-Valve Junior, Valve Special, Valve Standard)
Allow you to run the output of your amplifier to an external speaker cabinet.
Rating: Valve Junior: 4 Ohms. Valve Special and Valve Standard: 8 Ohms"


I have the Standard. So mine is 8 Ohms total. I think I have to disconnect the internal speaker before I connect an external one. What do you think?

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Re: Tube Amp External Speaker

Post by Ricochet » February 23rd, 2008, 7:29 pm

Usually you are advised to unplug the internal speaker when you plug in another. Probably wouldn't blow anything if you didn't, but they won't warrant the repair if they know you didn't follow directions and something did happen. That amp may be made to use both outputs. The owner's manual should say if it is OK. On my Valve Junior I have no choice but to unplug the internal speaker as it only has one jack.
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Wes Inman
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Re: Tube Amp External Speaker

Post by Wes Inman » February 25th, 2008, 2:29 pm

RiffRaff

I'm glad you read your manual. :D

It may not hurt your amp to run at 4 ohms, but why take a chance? I am no electronics expert by any means, but I believe impedence matching is more critical with solid state amplifiers. Ohms is a measure of resistance. The lower the ohms, the lower the resistance to current flow. When you operate an amp below it's recommended minimum impedence rating, it's pretty much like turning your amp into an electric toaster. :shock:

So yes, if you want to use an external speaker or cab, disconnect the internal speaker. The silly thing to me is, why give a person two Speaker Out jacks? It's just asking for trouble.

You could run two 16 ohms speakers or cabs off each jack safely though.
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Re: Tube Amp External Speaker

Post by MrJonesey » February 25th, 2008, 7:12 pm

If the manual isn't clear, you could try contacting a service rep for your amp. I called the manufacturer of my amp (Rivera) and was told that it was absolutely safe to run and 8 ohm cab and the internal speaker at the same time. He suggested that I might like the sound better to just run either the cab or the internal speaker alone, but assured me that I would be absolutely safe in doing so. But each amp is different, so don't do it unless you're sure.
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Re: Tube Amp External Speaker

Post by Riff Raff » February 26th, 2008, 3:44 am

Thanks everyone. The manual is a little unclear as I read it. I think I'll send an email to Epiphone. I'll let you know what they say.

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Re: Tube Amp External Speaker

Post by Riff Raff » February 27th, 2008, 10:24 am

Well, I sent an email to Epiphone and got a response:
To: Customer Service1
Subject: Epiphone Valve Standard Tube Amp

I have an Epiphone Valve STANDARD, 15 watt tube combo. It has two
speaker outputs in the back. One of them is being used already by the
built in speaker and it is labeled "Speaker - 8 OHM". The other one is
labeled "8 Ohm min".

Can I plug in another 8 ohm cab and leave the internal
speaker plugged in, or do I need to unplug the internal speaker before
plugging in another 8 ohm cabinet?

Thanks,
Dave
You can plug in another 8 ohm external speaker without unplugging the internal speaker. Thank you for the inquiry.

Regards,
Roger Ball
Gibson customer service
service@gibson.com
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Re: Tube Amp External Speaker

Post by Ricochet » February 27th, 2008, 10:32 am

Nice to know!
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Re: Tube Amp External Speaker

Post by 97reb » February 27th, 2008, 2:56 pm

Yeah, that is great to know
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