Musician Gear & Tech Discussion

I'm sorry Sans. When I spoke of the over use of effects, I was mainly talking about kids. I should have been more clear about that.

Secondly, you should be careful about plugging your preamp in another speaker cabinet unless you understand the Ohms. If you have a mismatch in Ohms, you can do internal damage as well. And that will void your warranty. You should just sit tight with it until you speak with a tech.

Stop that Shred, you're making me shiver.. lol

I want to plug in my Yamaha emx-300 (250 watts at 8 ohms) into my 2 Kustom cabs (5 speakers, unknown watts at 16 ohms) and then I read your last post. I can almost hear the cabs shorting out as the board spontaneously ignites.

Anyone have a fire extinguisher>? lol

I understood your point Shredd, I was agreeing with you in my own twisted way not being defensive.
The Nomad has two speaker out ports. plus the effects loop and Cab voiced out as well as an 4, 8, & 16 Ohm switch.
The Yama's are 8ohm speakers so If I understand this theory I was safe.
However this is one of the questions I have written out for the Carvin Tech. I studied electronics in college, but damned if I remember any of it due to the (sniff,,snort,, sniff) distractions of youth. Seems if you have two 8 Ohm speakers in series then it's 4 Ohms, parallel remains at 8 Ohms. Any suggestion as to where to find a morons guide to Ohm?

OK, Tech at Carvin had me check to see if al the tubes were the same manufacture / style in preamp Sovtec 7025/12AX7WA - GT12Ax7R
Had me tighten all screws. Told me that the Cab voiced out is not a load and needed to maintain the Cab speaker connection unless using the speaker outputs to another Cab. The speaker outs are parrallel wired so When I plug in my two 8 Ohm speakers to switch the amp into the 4 Ohm mode. Geeze I hate being wrong all the time. Live and learn I guess. Hope I didnt F/U anything. Going to go play the amp now. wish me luck and no freakin rattles. (still not so sure about that whole Ohm thing though, just dosent seem right to me)

So is it ok?

Less rattle but it still aint perfect
Me thinks it may be the speaker. I freakin hate having to return stuff, then wait for it to come back like Christmas or something.
I will call em back again tomorrow. Maybe I can get them to send me a speaker to install. Tonight I,ll just turn up the monitors for practice.

Here, check out this link Sans. It might help.

http://forums.carvinmuseum.com/viewtopic.php?t=19832

I believe the speaker load works like this: 1/8+1/8= 2/8= 1/4= 4ohms.

If it turns out you need some tubes Sanshouheil, let me know about any questions you might have, you know I'd be glad to help.

Howlin

Gotta disagree with ya on this one, pedal vs knob is a big difference. I've used a volume pedal for over 20 years, I never play without it any more.

1. Never have to take my hands off the strings to change volume. Most guitar players have to stop and turn the volume up or down, then find their place in the song again. I just keep playing.

2. I don't lose treble. When I turn down, it's not cutting the pickup output, just the signal strength. Still cleans up, but keeps the treble I lose if I use the knob. Being a tone junkie this counts. A lot.

3. Better control over the volume level at any time, just move my foot.

The guy who got me started with a volume pedal told me if I used one for a month or two, I'd never play without one again. He was right, now I'm telling other guitar players the same thing, over 20 years later. It does mean one more box on the floor, but the advantages are definitely worth it. I didn't like it at first, his Dunlop was sensitive, I had to train my foot to cooperate with the thing, and I had to get over the same idea...these things are for keyboard players, guitars have volume knobs...

Once I tried it and got accustomed to using the pedal, I'll never play without one again, it's great. I even take my volume pedal and a short cable if I go out and think some band might want me to sit in. (always take my own guitar too, I don't let anyone touch my guitars onstage, I don't like to play theirs either)

I do occasionally use the knob, if I want to pull back the treble a bit, or tame a distortion pedal a little for rhythm parts, but that's not often. For tone changes I use mostly the pickup switch.

Captain:

If your speakers are wired parallel, it can work. Do the Kustom columns have two jacks? I don't remember...if so, wire one cable between the two, then another to the second jack of one speaker and check it with a multimeter. It should fall in the range of 7-10 ohms or so, usually on the low side. My 8 ohm speakers show around 6-7 ohms when not under a load. That changes once it's plugged in, 8 ohms is the 'nominal' rating, which means it wil be in the ballpark, but not necessarily exactly 8 ohms. If both wired together show 7-10 ohms it should be safe to use them with the 8 ohm PA. If it shows 32 ohms, forget it, you're wired series. I'm betting parallel, most are.

In theory, 16 ohms should be able to work, running a lower impedance speaker is more dangerous than a higher impedance. Run a 4 ohm load on a 8 ohm tube amp and you're asking for trouble. The general concensus among amp techs is one step either direction, but I stay away from a lower impedance load. Speakers are usually 4, 8 or 16 ohms. 16 ohm speakers should be ok with a 8 ohm amp, but bad idea with a 4 ohm amp. 4 ohm speakers should be ok with a 8 ohm amp, but not a 16 ohm amp. I don't like to risk it, I keep mine matched.

I blew a diode in a solid state amp many years ago by running about a 2 ohm load on a 8 ohm amp. Fortunately it was still under warranty and was fixed at no charge, and a diode is cheap. (they didn't ask about my speaker setup and I didn't tell them, it was a combo amp, I guess they didn't consider that I might have been running 2 other speaker cabinets as well...) Transformers are not cheap. The power transformer for my Peavey MX cost me $120 about 2 years ago, and that's what blew it. The jack in my old Kustom 2x12 cabinet was worn out and loose, while playing it kept losing contact and getting it back really quick due to vibration, the load/no load/load scenario was too much for the transformer. By the end of the night it was sounding like the amp was gargling...at low volume while the jack stayed put and after the jack was replaced...running mismatched is not that bad, usually it won't cause any serious damage, but don't run a really mismatched rig like I did. If I had been running 4 ohms in the other situation, it probably would have kept right on playing and the diode would still be alive. I got lucky, it made the night and blew the diode soon as I flipped the power switch next day to practice. I'm not sure why, it seems like it would have toasted parts while I was onstage cranked to near ear bleeding levels, but it made it...this was 1975, there was only one way to play...LOUD...100 watt amp maxed out and wanted more...

Thanks Shredd6: At least I am not alone, sounds just like the problem I am having. I think for now I'm just going to switch to 4 Oms and play it through the Yamaha speakers. No rattle at all like this. I'll do the push test on my tubes when I have time and an extra set of hands around.
On reflection perhaps I would have been better off just buying one of the 50/100 watt heads. Live and learn. I flipped the tiny internal switch on my V pedal yesterday. It seems to give me better control. Less sensitive I think. I am going to give myself a couple months on the V pedal as Pete suggested. I really am good with my feet and need to maintain my focus on the fretboard till I am a stronger player.

Oh Pete, I feel like you just gave me your last Bud-light, man. Thanks ever so much, I can't really express how grateful I am to you at this very moment.

And yes, I am wired in Parallel so that's what I will do. I will start running the 2 Kustom Columns as mains and then use 2 little shitty stage monitors as well and it will all be golden. (Is something burning?) (Ah sorry, just my ashtray) lol (for now)

And I only have one speaker input per cab, so I'll have to figure out another way to check that with the multimeter. (In truth if I cooked the 2 cabs, I'd probably laugh evily and then chuck em. I have had those bastards for a while now. But, that emx-300 would break me down if I toasted it. I have been trying to get one for a while now and it seems that although people like the newer stuff better, they aren't dumb enough to part with them for a song and a dance.)

Did I mention that I was extremely thankful that you answered my question? THANKS AGAIN PETE, I OWE YOU TOUGH.

OK, first, you're welcome.

I'm not sure how the Kustom PA cabs were done, but if they have a big enough jack plate it's not difficult to wire in another jack, parallel. You only need it on one, or you could make up a jack box, wired parallel, one in and two out. You can pick up project boxes at radio shack or local a electronics house, (that would be my preference, radio shack sells crap and I don't want it onstage). The down side is you have to cut another hole in a vintage cabinet...I don't know about you but I don't make any cosmetic modifications to my vintage equipment.

The wiring is pretty simple, input tip to both output tips, input sleeve to both output sleeves. Cut a few short strips out of an old extension cord and slip the wires, it's usually 14 gauge, which is plenty for that application.

If the output jacks in your PA are parallel, just make sure they keep it at an 8ohm load when both jacks are used. For example, the Peavey Classic 30 guitar amp is 16 ohm, but if you plug a jack into the external speaker output, it switches it to the 8 ohm tap of the output transformer for a 8 ohm signal. Since it's parallel, that means two 16 ohm cabinets and you're set. If yours turns into 4 ohm using both jacks, 16 ohm cabinets wouldn't be a great idea. 8 ohm cabs might be ok, but 16 is too much difference in impedance.

If it were me, I'd spend about $20 and make up a jack box, to make sure I'm running parallel and the correct impedance, and once you're plugged into everything but the amp, you can check impedance at the jack that will be plugged into the amp.

gulp... lol

Thanks, I'll go the jack box route. Toasting anything doesn't really sound like much fun if I have to repair it.

Now If I could just throw it out and replace it, it picks up a little appeal.

Check this out..




Mike Einziger from Incubus.. What a freaking stud. This rig kills.

My lil cheapo Ernie Ball volume pedal has worked for me for many years...dunno what I'd do without it, both on electric & acoustic.

He must have studied tap dance