Members ZigmundFloyd Posted August 15, 2007 Members Share Posted August 15, 2007 I just bought one of these beauties, great shape for $199. Sounded killer in the store, but I have a slight problem at home as I do not own an 8 ohm cab, hence the question. There are two spkr. outs, one marked: Speaker 8 ohm, and the other marked: External Speaker 4 ohm. Do I need 2 8 ohm loads to use this amp at 4, or can I use a 4 ohm cab in the Ext. out only? Found this on ampage, it was on the internet so it must be true: Re: Sunn Sceptre Guitar Amp head -------------------------------------------------------------------------------- The Sunn heads have 4,8,and 16 ohm taps on the output. Only two are brought out to the back panel depending on the model. The Sceptre has 4 and 8 brought out with the 16 tied to a lug strip on the inside. When you plug in to the jack marked 4 ohm, it switches both jacks to the 4 ohm tap so that you can use either two 8 ohm cabinets or one 4 ohm cab. I wire my home built amps the same way. I own about 10 tube Sunn amps and one hybrid they called the "Solos" JM John Martin Do you agree with this? One reason I ask, is that on a 70's SVT, the outs are also labeled spkr and ext spkr , and 2 4 ohm cabs cannot be daisy chained, they must each go into the separate jacks in order to hit the 2 ohm tap. Plugging anything into the ext jack will not work if the main jack is not engaged. So before I go farting around and blowing up the output trannie, I thought I'd ask around. Thanks Link to comment Share on other sites More sharing options...
Members bassred Posted August 15, 2007 Members Share Posted August 15, 2007 as long as your cabs aren't bleow the rated resitance you should be OK to plug them in and try them out, just start with lower volume and see if the sound is coming out..... My first 'real' amp was a sceptre with the matching 4X12 cab, I loved that thing, but had a huge rig when I sol it (I wish I hadn't now...damned hindsight) Link to comment Share on other sites More sharing options...
Members Guttermouth Posted August 15, 2007 Members Share Posted August 15, 2007 as long as the amp hasn't been modified you will be fine running a single 4 ohm cab on the ext output. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted August 15, 2007 Moderators Share Posted August 15, 2007 I just bought one of these beauties, great shape for $199. Sounded killer in the store, but I have a slight problem at home as I do not own an 8 ohm cab, hence the question.There are two spkr. outs, one marked: Speaker 8 ohm, and the other marked: External Speaker 4 ohm. Do I need 2 8 ohm loads to use this amp at 4, or can I use a 4 ohm cab in the Ext. out only?Found this on ampage, it was on the internet so it must be true:Re: Sunn Sceptre Guitar Amp head --------------------------------------------------------------------------------The Sunn heads have 4,8,and 16 ohm taps on the output. Only two are brought out to the back panel depending on the model. The Sceptre has 4 and 8 brought out with the 16 tied to a lug strip on the inside. When you plug in to the jack marked 4 ohm, it switches both jacks to the 4 ohm tap so that you can use either two 8 ohm cabinets or one 4 ohm cab. I wire my home built amps the same way. I own about 10 tube Sunn amps and one hybrid they called the "Solos" JM John MartinDo you agree with this?One reason I ask, is that on a 70's SVT, the outs are also labeled spkr and ext spkr , and 2 4 ohm cabs cannot be daisy chained, they must each go into the separate jacks in order to hit the 2 ohm tap. Plugging anything into the ext jack will not work if the main jack is not engaged.So before I go farting around and blowing up the output trannie, I thought I'd ask around.Thanks It doesn't matter if anyone agrees or not. It's a fact. That's the way the output is wired. Plug your 4 ohm cabinet into the 4 ohm jack, and all will be well. Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted August 15, 2007 Members Share Posted August 15, 2007 as long as your cabs aren't bleow the rated resitance you should be OK I think you mean above the rated impedance. Tubes amps need the rated or lower. Link to comment Share on other sites More sharing options...
Members bassred Posted August 15, 2007 Members Share Posted August 15, 2007 No, if you have resistance that is lower than the amp is designed for things can go bad... Never go lower than the rated resistance. Higher resistance meens your amp will be working a little harder and not putting out as much power, this is the theory behind the Marshall powerbrake and THD hotplates, make the power output face a higher resistance to saturate the tubes and get that 'sweet' sound at a lower volume level.. if this was such a bad thing (to go above the rated Ohms) these products would ever have gone to market. Link to comment Share on other sites More sharing options...
Moderators Kindness Posted August 15, 2007 Moderators Share Posted August 15, 2007 No, if you have resistance that is lower than the amp is designed for things can go bad... Never go lower than the rated resistance.Higher resistance meens your amp will be working a little harder and not putting out as much power, this is the theory behind the Marshall powerbrake and THD hotplates, make the power output face a higher resistance to saturate the tubes and get that 'sweet' sound at a lower volume level.. if this was such a bad thing (to go above the rated Ohms) these products would ever have gone to market. You are wrong. It is best to have an impedance match. It is generally okay to be off by one degree (2 ohm cab on 4 ohm tap or 8 ohm cab on 4 ohm tap). However, if you are off by a degree, it is better to be under the rated impedance than above it. The rules may be counter-intuitive if you are used to solid state devices. Link to comment Share on other sites More sharing options...
Moderators Kindness Posted August 15, 2007 Moderators Share Posted August 15, 2007 as long as the amp hasn't been modified you will be fine running a single 4 ohm cab on the ext output. Truth. Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted August 15, 2007 Members Share Posted August 15, 2007 No, if you have resistance that is lower than the amp is designed for things can go bad... Never go lower than the rated resistance. Higher resistance meens your amp will be working a little harder and not putting out as much power, this is the theory behind the Marshall powerbrake and THD hotplates, make the power output face a higher resistance to saturate the tubes and get that 'sweet' sound at a lower volume level.. if this was such a bad thing (to go above the rated Ohms) these products would ever have gone to market. You've got it all wrong.... What's the resistance/impedance of a 3" piece of 12AWG wire? Would that be more or less of a load than a 8 ohm speaker? For a more dynamic demonstration of this concept, short the terminals of your car battery with a tire iron. When/if you're able, come back and tell us what you learned. Link to comment Share on other sites More sharing options...
Members ZigmundFloyd Posted August 23, 2007 Author Members Share Posted August 23, 2007 OK...well thanks for the info Link to comment Share on other sites More sharing options...
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