An ohm question

[parkerbro]

I love to play guitar but know little about the inner workings of gear.

That said, I just picked up a Winfield Cyclone head. I've been playing it through the cab in my combo. I just traded for a 212 loaded cab to go with the head. I was sure the cab was 8 ohm but come to find out that the cab is 16 ohm.

I'm pretty sure the cyclone head is 8 ohm only. Can I play the 2 together? What are the implications? What can I do?

Thanks in advance for any help!

[BluePat]

Hi,

Double check if there is an impedance selector on the back of the amp, and match it to the impedance of the cab, safest bet. Conventional wisdom is a mis-match of one increment up or down i.e. 8 ohm tap on transformer coupled to a 4 or 16 ohm load *SHOULD* be ok, but a leap of two i.e. 4 ohm tap coupled to a 16 ohm load, or 16 ohm tap coupled to a 4 ohm load is bait for trouble. English output transformers are supposedly more finicky in this respect (Dagnall, Drake, etc) but nothing's guaranteed...

Use the search function, there is LOTS of information on this subject.

Hope this helps.
Pat

[paolojm]

I personally wouldn't worry about this mis match, it's most unlikley to cause problems. Older Fenders regularily ran/run with mismatched speakers. It only becomes a problem if the OT was underspeced to start with or you have a more serious mis match like 4 ohm head into 16 ohm cab.
It will reduce the output power very slighty and may noticably reduce the top and bottom a bit.

[thilton59]

As a general rule, you can have an up to 200% mismatch without issue.

[SatelliteAmps]

This all depends on the amp. Some amps are fine, some aren't. There is NO general rule about mismatches. Fenders are usually fine with 200% mismatches, while Marshalls aren't.

To be safe, the best bet is to email the manufacturer and ask them.

[strat a various]

You're hurting my math. 100% over unity is 8+8=16. One more 8 is 100% more. 200% more is 8+8+8=24. That's 100%(8) over matching, plus another100%(8) over that.
I think we wanted to say a 100% mismatch is OK. Whether that's a good rule of thumb is debatable.

[thilton59]

Thanks for the correction Adam. I might want to start thinking outside the Fender box when giving advise...

[SatelliteAmps]

You're hurting my math. 100% over unity is 8+8=16. One more 8 is 100% more. 200% more is 8+8+8=24. That's 100%(8) over matching, plus another100%(8) over that.
I think we wanted to say a 100% mismatch is OK. Whether that's a good rule of thumb is debatable.

Depends on how you want to word the math. It can be written out so that a 16Ω load on an amp that wants 8Ω is an EXTRA 100% mismatch, or it can be said to be a 200% mismatch. Both are technically correct, and both a potentially damaging.

To screw the match a bit more, going down is also the same percentage of mismatch. A 4Ω load in the same situation is not a 50% mismatch.

[strat a various]

or it can be said to be a 200% mismatch. Both are technically correct

I don't think so.
But your heart's in the right place. Either way, "more than double is impedance trouble." All together now.

[Old Tele man]

...BEST = Z = Z

...GOOD = between Z/2 and 2*Z

...BAD = greater than 2*Z

...OK = less than Z/2 ...(not harmful to amp, but does diminish output quickly!


note: Z = 'optimum' (what it's designed for) amplifier OT impedance value.

[SatelliteAmps]

I don't think so.
But your heart's in the right place. Either way, "more than double is impedance trouble." All together now.

200% of 8 is 16.

100% of 8 is 8. Add 100% of 8 plus 100% of 8, and you have 16, which is how it can be meant when someone talks about a 100% mismatch. The math for both is the same, just worded differently.

It can be written in a number of ways that all mean the same thing. That was my point. It had to do with the comment I quoted, saying the math was getting confusing.

...GOOD = between Z/2 and 2*Z

...BAD = greater than 2*Z

...less than Z/2 is actually not harmful to amp, but does diminish output quickly!

...note: Z = optimum amplifier OT impedance value.

...Good = Z=Z

...Usually OK = between Z/2 and 2*Z (replacing a 1976 Marshall OT tonight because someone thought this was "ok" and that it sounded "better.")

...BAD = greater than 2*Z

[Tone_Terrific]

...Usually OK = between Z/2 and 2*Z (replacing a 1976 Marshall OT tonight because someone thought this was "ok" and that it sounded "better.")


Could you please describe the failure mode, here.
Did one side open, both, overtemp, they let the smoke out or ?

[SatelliteAmps]

I wasn't there when it blew, so I didn't see any of the magic smoke escape. Not sure what to describe failure mode wise. Customer pretty much knew what happened before he brought it to me. I just popped it open and did a few quick tests, and one part of the primary is open. Didn't look much further than that.

I can ask him for more specific details if you want to know more.

[Tone_Terrific]

one part of the primary is open..

That's fatal.
I was just wondering how long it took to happen and if there was advance warning.

[parkerbro]

thanks for everyone's input so far. i got the 16 ohm cab and played it with the 8 ohm head. it sounds fine. i also checked with the builder and he said there won't be a problem but i'm better off if i switch the wiring to make it 4 ohm. he didn't explain why.

so why is that better - 8 ohms into 4 vs. 8 ohms into 16?

also, i've never played through a 2x12. is it my imagination or is it much louder playing through two speakers? i guess it's double the volume due to the 2 speakers.

thanks everyone - this is a great place to learn!

[SatelliteAmps]

That's fatal.
I was just wondering how long it took to happen and if there was advance warning.

No advance warning. Never really is. When a transformer (or speaker or any coil really) melts, it is almost instant. There is no warning, and no way to get out once it starts to go. The owner said he turned it on and it just sounded weird. He messed with it himself a bit, but I don't know for how long. Probably melted as soon as he hit the first note when it was turned on.



thanks for everyone's input so far. i got the 16 ohm cab and played it with the 8 ohm head. it sounds fine. i also checked with the builder and he said there won't be a problem but i'm better off if i switch the wiring to make it 4 ohm. he didn't explain why.

so why is that better - 8 ohms into 4 vs. 8 ohms into 16?

also, i've never played through a 2x12. is it my imagination or is it much louder playing through two speakers? i guess it's double the volume due to the 2 speakers.

thanks everyone - this is a great place to learn!


Playing through the same type of speakers, as a 2x12 compared to a 1x12, there is a volume difference. It's not double the volume, but it is noticeable.


There are reasons to go either way with a mismatch. One way makes the amp work harder, and stresses (potentially overheating) the output transformer. The other way increases the risk of flyback voltages, also melting the OT. Going higher makes the transformer work harded, greatly reduces output, and risks meltdown. Going lower risks flyback. This is a bit simplified, and there is more to it than this, but I don't know how technical you want.

[parkerbro]

Adam, when you say going higher, do you mean higher speaker ohm to head? if that's the case, if i rewire to 4 ohm will it be that much louder? also, why do you think the amp builder, winfield, strongly recommended having lower speaker to head? thanks!