Ohmage question.

[guitarpkr67]

Hey guys. I just got a Bassman 100 for our bass player to use. Which is a 4 ohm head. Well, he went and bought a 8 ohm cabinet today. My question is: Will it hurt to use it with a 8 ohm cab? If so, would it be difficult to rewire the cab for 8 ohms? Thanks for any help.

PS. If anybody has any suggestions for some good, decent priced 6l6s that would be awesome.
Thanks.

[Kelly]

You'll be fine with an 8 ohm cab. There is no such word as ohmage. You mean impedance.

[guitarpkr67]

Dictionary.com Unabridged (v 1.1) (http://dictionary.reference.com/help/luna.html) - Cite This Source (http://dictionary.reference.com/cite.html?qh=ohmage&ia=luna) - Share This (http://dictionary.reference.com/browse/ohmage#sharethis) ohm·age http://cache.lexico.com/dictionary/graphics/luna/thinsp.png /ˈoʊhttp://cache.lexico.com/dictionary/graphics/luna/thinsp.pngmɪdʒ/ Pronunciation Key - Show Spelled Pronunciation[oh-mij] Pronunciation Key - Show IPA Pronunciation –noun Electricity. electric resistance expressed in ohms.
[Origin: 1895–1900; ohm (http://dictionary.reference.com/search?q=ohm) + -age (http://dictionary.reference.com/search?q=-age)http://cache.lexico.com/dictionary/graphics/luna/thinsp.png]



I could be using it in the wrong context though. I just think the word sounds cool.:)

[HandOfTheHost]

I wouldn't do that. He's probably going to crank it and that's where you're going to run into problems. I would get another 8 ohm cabinet and run them parallel, bringing the impedance down to 4 ohms. As far as tubes go, TAD, JJ, and Svetlana 'Winged C's' come highly recommended.

[guitarpkr67]

I guess I'll just end up rewiring the cab. Thanks guys.

[drbob1]

Most Fender amps will survive just fine with a higher (by no more than a factor of 2X) output impedance. That said, 4 ohms or 2 ohms would be slightly safer if he's cranking it. There's no way you can rewire an 8 ohm cabinet to 4 ohms. If it's two speakers, they'll be either two 4 ohmers in series (can be wired to parallel for 2 ohms) or 2 16s in parallel (you're toast). If it's one speaker, the only thing you could do is add another speaker or cab in parallel, or drop in a 4 ohm speaker instead.

Good 6L6s? Lots of cool stuff out there, check out Lord Valve or KCA tubes for good suggestions...

[guitarpkr67]

So...if he's not cranking the amp running the 8-ohm cab should be fine. For instance if he's running the amp halfway on the volume and master volume for a couple hours he should be good? Or would that be too much for the amp to handle?

[blackba]

The bassman 100 has a beefy transformer and should run fine at 8ohms. You won't get the max power out of it though and I thought my Bassman 50 sounded better into a 4ohm load.

What cab did he get, 210, 410, 212????

For power tubes check out the =C= SED 6L6's. Doug's tubes or KCAnostubes should have them...

[guitarpkr67]

He bought a Ernie Ball Audiophile 4-10. He got a pretty good deal on it.

[Matybigfro]

hehe now you've given the ohm calculators something to get warm about

how many amp outputs does the amp have

if the speakers are 8 ohm each you could wire it for two speakers to two 4 ohm jacks a pair in paralell

[blackba]

He bought a Ernie Ball Audiophile 4-10. He got a pretty good deal on it.

FYI, There is no way to wire an 8ohm 410 to 4ohms. A 410 8ohm cab will have 4 8ohms speakers wired in series parallel. You can also wire them all in parallel give you 2 ohms or all in series giving you 32ohms.

[coolhand78]

does the bf bassman head (50watt) have 2 parrallel 8 ohm outs giving a 4 ohm total or is each of the outs 4 ohms giving it a 2 ohm total... (assuming both the speaker and ext speaker outputs are in parrallel)? or is it something else all together... i'm getting a cab built and want to know if it should be 4 or 8 ohms? and i'll only be using one of the speaker outs...

cheers

[drbob1]

The BF Bassman wants a 4 ohm cabinet.

You should rewire the 410 to 2 ohms, it's just a little safer. It be great if you could bias the power tubes into the 2 ohm load as well, that'd give you the best performance.

[steadygarcia]

FYI, There is no way to wire an 8ohm 410 to 4ohms. A 410 8ohm cab will have 4 8ohms speakers wired in series parallel. You can also wire them all in parallel give you 2 ohms or all in series giving you 32ohms.

Is there a way to rewire a 16 ohm 4x10 cabinet to 8 ohms? This is a cabinet that has a switch to convert it from 8 ohms in stereo to 16 ohms in mono.

[drbob1]

Is there a way to rewire a 16 ohm 4x10 cabinet to 8 ohms? This is a cabinet that has a switch to convert it from 8 ohms in stereo to 16 ohms in mono.

To have an 8 ohm, 4 speaker cab, they're using 8 ohm speakers. The way to calculate impedance is 1/a+1/b=1/c where a and b are the impedances of two speakers and c is the result, when wired in parallel, or a+b=c where they're in series. So they've wired two in parallel (4 ohms) and two sets of those in series (back to 8 ohms). Yeah, if you split it into 2 sets of two speakers, each will likely have a 4 ohm impedance, but can only handle 1/2 the power. Seriously, just connect all 4 in parallel (all the + and all the - terminals together) and you've got 2 ohms which is perfectly safe (what the bassman was expecting if you used an extension cab).

[steadygarcia]

To have an 8 ohm, 4 speaker cab, they're using 8 ohm speakers. The way to calculate impedance is 1/a+1/b=1/c where a and b are the impedances of two speakers and c is the result, when wired in parallel, or a+b=c where they're in series. So they've wired two in parallel (4 ohms) and two sets of those in series (back to 8 ohms). Yeah, if you split it into 2 sets of two speakers, each will likely have a 4 ohm impedance, but can only handle 1/2 the power. Seriously, just connect all 4 in parallel (all the + and all the - terminals together) and you've got 2 ohms which is perfectly safe (what the bassman was expecting if you used an extension cab).

Sorry, my bad. I wasn't talking about the OP's amp -- I was just adding a similar question to the thread. I was referring to a cabinet for which the only info I have is that it has a switch to run either 8 ohms in stereo or 16 ohms in mono. And it's a 4 x 10 cab. I'm trying to do the math and have done a search for "impedance" on TGP as well as Googled, and still can't figure it out. Sorry, didn't mean to hijack.

[ToneGrail]

Just have him get a Weber Impedance matcher and be done with it.

https://taweber.powweb.com/store/zmatch.htm

[guitarpkr67]

Just have him get a Weber Impedance matcher and be done with it.

https://taweber.powweb.com/store/zmatch.htm

That thing is sweet. Not sure if he can swing it right now, but I'll keep that in mind. Thanks.

[HandOfTheHost]

Some pretty reasonable solutions here: Cheapest, wire the cab for 2 ohms sacrificing some performance. Or add an 8 ohm 1x15 and run the two in parallel. Or buy the Weber impedance matcher.
I still suggest adding a cabinet, you'll be pushing more air and getting the most out of the amp. Surely you can find a 1x15 p.a. cab that nobody's using.

[blackba]

Is there a way to rewire a 16 ohm 4x10 cabinet to 8 ohms? This is a cabinet that has a switch to convert it from 8 ohms in stereo to 16 ohms in mono.

You can't wire a 16ohm 410 cab in mono to 8ohms. You could wire all the 16ohm internal speakers in parallel and get a 4ohm cab mono.