Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 Just noticed my speaker in there is 15 Ohm, and the selector is for 8 Ohm. I know this is OK since higher impedance doesn't overload the amp. Now... if I hookup an extension cab with a 16 Ohm speaker in it, I get a little less than 8 Ohms... should I run the selector at 4 Ohms? Can I safely run at the 16 Ohm setting right now?I typically try to run at the correct setting always, so this 15 Ohm speaker is throwing me off. Advice?FYI: I can run 4, 8, 16 Ohms off the amp with the selector.PS - the reverb is tube drive, gonna replace that tube and see how it responds. Bump on this? Link to comment Share on other sites More sharing options...
Members roquero Posted June 20, 2010 Members Share Posted June 20, 2010 You scored a great deal! I paid much more for my JCM800- it has 50 watts, 2 12s and the Vertical inputs Sounds so much sweeter now that I installed Weber Beam Blockers- you may want to consider them for your baby- it's a twenty dollar upgrade! One benefit to the beam blockers is that the sound is diffused and I can get away with turning the amp louder at gigs without incurring the wrath of the sound man. Mine belonged to the guitarist in Joe Perry Project- no not Joe, the other guy. Still has the Sharpie mark on 8 on the pre gain where he had it set! Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted June 20, 2010 Share Posted June 20, 2010 15 ohms... I in the general direction of whomever it was who thought THAT was a good idea... Anyway, I'd set the amp to the 16 ohm output setting and use that when running just the internal. I don't think that 1 ohm difference is going to make a bit of difference in the real world. Those are "nominal" impedance ratings, and a speaker isn't static in terms of resistance. Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 15 ohms... I in the general direction of whomever it was who thought THAT was a good idea... Anyway, I'd set the amp to the 16 ohm output setting and use that when running just the internal. I don't think that 1 ohm difference is going to make a bit of difference in the real world. Those are "nominal" impedance ratings, and a speaker isn't static in terms of resistance. Ah, thanks, Phil!! I'm gonna try running at 16 and see if there's a difference. Link to comment Share on other sites More sharing options...
Members Saturnine10 Posted June 20, 2010 Members Share Posted June 20, 2010 I dont think you actually hear a tonal difference between running different ohm settings.. If anything you'll hear your output tranny pop *i think* Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 I dont think you actually hear a tonal difference between running different ohm settings.. If anything you'll hear your output tranny pop *i think* This is precisely the scenario I want to avoid. Link to comment Share on other sites More sharing options...
Members Dr.Pain-MD Posted June 20, 2010 Members Share Posted June 20, 2010 Congrats on the deal, that's a sweet score! You should be fine running the 15 ohm speaker at 16 ohm amp output impedance because speakers are never perfect and are never exactly 16 ohms even when they say they are. The minor difference should not be a problem at all. Link to comment Share on other sites More sharing options...
Members roquero Posted June 20, 2010 Members Share Posted June 20, 2010 Oh, I know about the benefit of Beam Blockers! Have them on my Fender Hot Rod Deville to get rid of ice pickyness (has WGS Vet 30s, which can be bright). I may try them out with this, though!Any chance you can check your amp output impedance selector and see what that's set to? You're running 2 - 15 Ohm speakers, so I figure 4 Ohm would be the safest, but you might be able to run at 8 Ohms. Mine is set to 8 ohms, which is the way the amp came, and the way my amp tech [who serviced it for the Joe Perry Project guy] leaves it Two 16 ohm speakers in parallel is 8 ohms total load [although the speakers say 15 ohms each- unfortunately, I don't have a switch for 7 Link to comment Share on other sites More sharing options...
Members mr benn Posted June 20, 2010 Members Share Posted June 20, 2010 my celestion Golds are 15 ohm,but when checking it out at the time in some ampy type forums everyone just said "treat them as if they are 16ohm" Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 Congrats on the deal, that's a sweet score! You should be fine running the 15 ohm speaker at 16 ohm amp output impedance because speakers are never perfect and are never exactly 16 ohms even when they say they are. The minor difference should not be a problem at all. Wish I could multiquote right now... but thanks everyone!Yes, this is something good to remember, and I didn't even consider breaking out the multimeter and actually measuring the impedance () but I have no worries about running it at 16 Ohm now! Link to comment Share on other sites More sharing options...
Members EL KABONG Posted June 20, 2010 Members Share Posted June 20, 2010 UMMM {censored} YOU!! Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 UMMM {censored} YOU!! Link to comment Share on other sites More sharing options...
Members Bobby D Posted June 20, 2010 Members Share Posted June 20, 2010 You scored a great deal! I paid much more for my JCM800- it has 50 watts, 2 12s and the Vertical inputs Sounds so much sweeter now that I installed Weber Beam Blockers- you may want to consider them for your baby- it's a twenty dollar upgrade! One benefit to the beam blockers is that the sound is diffused and I can get away with turning the amp louder at gigs without incurring the wrath of the sound man. Mine belonged to the guitarist in Joe Perry Project- no not Joe, the other guy. Still has the Sharpie mark on 8 on the pre gain where he had it set! oh yeah......LOVE that amp. that's one of my alltime faves......vert input 2x12 JCM800 early 80s model. those are REALLY close to the 70s JMP circuit. and it's already in the roadcase too if you ever want to trade it, let me know Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted June 20, 2010 Share Posted June 20, 2010 I didn't even consider breaking out the multimeter and actually measuring the impedance Don't bother... Actually, the next time you have it out, give it a try and see what it says... just don't be alarmed if it doesn't read 16 (or 15) ohms. Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 20, 2010 Author Members Share Posted June 20, 2010 Don't bother... Actually, the next time you have it out, give it a try and see what it says... just don't be alarmed if it doesn't read 16 (or 15) ohms. Yeah, I might do it eventually, but at least my worries have been calmed Link to comment Share on other sites More sharing options...
Members roquero Posted June 21, 2010 Members Share Posted June 21, 2010 oh yeah......LOVE that amp. that's one of my alltime faves......vert input 2x12 JCM800 early 80s model. those are REALLY close to the 70s JMP circuit. and it's already in the roadcase too if you ever want to trade it, let me know Hey Bobby- this one's a keeper, but if you ever want to take her out for a ride, let me know.We can have a Pedal Party and crank her up!Now that my band's broken up, I need to keep up the chops.Speaking of transactions, in another thread you said you may be looking for a Tele backup, this Yamaha Tele of mine may be up on Craigslist soon... Link to comment Share on other sites More sharing options...
Members Bobby D Posted June 21, 2010 Members Share Posted June 21, 2010 Hey Bobby- this one's a keeper, but if you ever want to take her out for a ride, let me know. We can have a Pedal Party and crank her up! Now that my band's broken up, I need to keep up the chops. Speaking of transactions, in another thread you said you may be looking for a Tele backup, this Yamaha Tele of mine may be up on Craigslist soon... which model is that? i love those Pacifica Teles, i could have snagged one of the Mike Stern sig models at Sam Ash when they were blowing them out, those are GREAT Teles. how much are you lookin at to let that go?like yours a LOT! we gotta hang out one of these days Link to comment Share on other sites More sharing options...
Members RoboPimp Posted June 21, 2010 Members Share Posted June 21, 2010 Almost... Robo's got the 4010, single channel version, no reverb. This one has reverb and is channel switching, although the other one can be, kinda, with an A/B box going into its two inputs. Single input for me. But thanks Crxsh!! on the single channel JCM800s you can't use an A/B boxcool score, flip that celestion 65 to some TGPer and plug a V30 in there and stand back. I've been using mine to power my leslie speaker Link to comment Share on other sites More sharing options...
Members jhamnett Posted June 21, 2010 Author Members Share Posted June 21, 2010 on the single channel JCM800s you can't use an A/B box cool score, flip that celestion 65 to some TGPer and plug a V30 in there and stand back. I've been using mine to power my leslie speaker Ah, didn't know you couldn't do that. Still, the volume knob interaction on this amp is dramatic!! Really goes from clean to balls out without much twist of the volume I like the 65 and think I'll keep it, but have some WGS Vet 30s in my Deville I could try... might plug it into my Deville's speakers Also, need some JCM800 into Leslie (cheesewheel?) clips!!! Link to comment Share on other sites More sharing options...
Members roquero Posted June 21, 2010 Members Share Posted June 21, 2010 which model is that? i love those Pacifica Teles, i could have snagged one of the Mike Stern sig models at Sam Ash when they were blowing them out, those are GREAT Teles. how much are you lookin at to let that go? like yours a LOT! we gotta hang out one of these days Just drop me a line if you want to hang out, since I don't have a band currently I have plenty of free time on weekends or eveningsThis one is a 311ms, it supposedly is based on the Mike Stern model although technically it's not.One just went on ebay for $371, but I am accepting offers- maybe you should try it out and see what you thinkBy the way, if you happen to know of a band looking for a slightly used guitar player,,, Link to comment Share on other sites More sharing options...
Members RoboPimp Posted June 21, 2010 Members Share Posted June 21, 2010 Also, need some JCM800 into Leslie (cheesewheel?) clips!!! [YOUTUBE]uFIvttAMPWo[/YOUTUBE] Link to comment Share on other sites More sharing options...
Members RoboPimp Posted June 21, 2010 Members Share Posted June 21, 2010 here it is with the EHX memory boy gqD3h2xNoA8 Link to comment Share on other sites More sharing options...
Members The P-Man Posted June 21, 2010 Members Share Posted June 21, 2010 Cool amps... The vertical input thing made very little difference to the 50 watt JCM800s - some minor construction differences - but no change to the circuit. The 100watt JCM800s did change however. Link to comment Share on other sites More sharing options...
Members RoboPimp Posted June 21, 2010 Members Share Posted June 21, 2010 Cool amps... The vertical input thing made very little difference to the 50 watt JCM800s - some minor construction differences - but no change to the circuit. The 100watt JCM800s did change however. the channel switching one with reverb is quite a bit different tho Link to comment Share on other sites More sharing options...
Members Bobby D Posted June 21, 2010 Members Share Posted June 21, 2010 damnit, i love robo's mancave i seriously wanna BURN ONE DOWN at casa robo one day, and make some videos. Link to comment Share on other sites More sharing options...
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