#1
I just bought a Bogner Duende head, and am extremely excited.

But I just looked at the impedance range, and it is just 8 ohms.

My cab is rated for 16...

Is there anything I can do, besides buy a new cab? I really want to keep the Duende, especially because i got a great deal on it.
#2
You are fine.
You can plug your 16 ohm cab into your 8 ohm head without fear of hurting anything.
You lose a percentage of your max volume when your cabs ohm is rated higher.

It's the other way around that's bad. You cannot plug a lower ohm rated cab into a head with a higher ohm rating.
Last edited by 667 at Mar 23, 2009,
#3
That's a relief.

The cab is rated for at least 20 watts (came with a Krank Rev Jr), so I should be fine, then.
#4
Ya, that's what you need to worry about.. wattage. Seems like you have it under control.
#5
cam wattage > head wattage
otherwise something blows up
#6
It is a 30 watt head. I would imagine that I would be fine, considering the same cab comes with the Rev Jr Pro 50 watt head.
#7
Quote by BeethovensBust
It is a 30 watt head. I would imagine that I would be fine, considering the same cab comes with the Rev Jr Pro 50 watt head.



Take it easy though. Even with the ohm mismatch (output not efficient), you probably shouldn't crank it.
#8
Quote by 667
Take it easy though. Even with the ohm mismatch (output not efficient), you probably shouldn't crank it.


Duly noted.

It's mainly going to be played at home/small practice sessions, so I woun't really need to worry about cranking it.
#9
Quote by 667
You are fine.
You can plug your 16 ohm cab into your 8 ohm head without fear of hurting anything.
You lose a percentage of your max volume when your cabs ohm is rated higher.

It's the other way around that's bad. You cannot plug a lower ohm rated cab into a head with a higher ohm rating.
****NO**** This is only true for SS amps. Do not use this cab until you've written to the company and gotten an answer to your question. The rule stated above can be the opposite for tube amps. Tube amps use an output transformer that reflect the load impedance back to the power tubes. Too high of an impedance can cause tube failure and other associated issues like burning up your output transformer. SS amps are happy with higher impedance and even an open circuit, but not tube amps.

If the manufacturer says it's ok to put a 16 ohm load on the the amp, then you are good. Otherwise don't.
#10
you could always get a new speaker instead of a full new cab. replace the speaker in the cab with something rated 8 ohms and over 30 watts. its cheaper to buy a new speaker than it is to buy a new cab.
#11


the information i gathered about the bogner says that its impendance is selectable and it only has 15w - so the speaker should be ok

Whodicted



Quote by stevo_epi_SG_wo
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Recognized by the Official EG/GG&A Who To Listen To List 2009
#12
DO NOT MISMATCH VALVE AMPLIFICATION. DO NOT.

Here's why:

If the Cab Ohmage > Head Ohmage, It causes strain on the Output Transformer (the most expensive part of an amp) and can cause it to fail.

So 16 Ohm Cab into an 8 Ohm Head = BIG NO NO.

If the Head Ohmage > Cab Ohmage, It causes strain on the Power Valves and makes them wear out faster (less expensive, but still an annoyance that makes your amp that bit less reliable)

So 8 Ohm Cab into a 16 Ohm Head = Still bad, but not AS bad.

---

Solid State Mismatch is absolutley fine, though some dB loss will be experienced. Solid State mismatch must be made so that the Cab ALWAYS has higher ohmage than the head.

So 16 Ohm cab into an 8 Ohm head is ok.

The other way around will cause the head to fail. Irreparably.
...
#13
^why is it that i can plug a speaker with "minimum of 4ohms" into my champ then? not doubting what you say but i'd sure like to know!

Whodicted



Quote by stevo_epi_SG_wo
france is laaaaame


Recognized by the Official EG/GG&A Who To Listen To List 2009
#14
That is an unexplainable phenominon. I think it's just because that's the case with Solid State amps, PAs and such, and nobody bothers to correct it. I'm certain that's the way round it goes though.
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#15
Quote by hendriko
^why is it that i can plug a speaker with "minimum of 4ohms" into my champ then? not doubting what you say but i'd sure like to know!

He didn't say you couldn't do it he just advised to NOT do it. I've always read too that with valve amps you need match the load or you risk undo wear and tear.
#16
hendriko, if the manufacturer says it's ok then you are fine. If the specs say the impedance is selectable, then select the correct impedance.

Are you trying to tell us that Fender spec'd the Champ as using any speaker with a minimum of 4 ohms? That sounds like a SS amp spec.
#17
^well fender actually encourages putting higher impendance speakers in there...but if it will wreck the OT, that'd be weird

its all tube though...

Whodicted



Quote by stevo_epi_SG_wo
france is laaaaame


Recognized by the Official EG/GG&A Who To Listen To List 2009
#18
well fender actually encourages putting higher impendance speakers in there.

Can you back that up?
#19
Quote by Fender Champion 600 Manual
SPEAKER - Connection for the internal speaker of a 4-ohm minimum external speaker cabinet


Well alright, its not really encouraging, but if it would do harm to the amp, they'd tell you I'd say

Whodicted



Quote by stevo_epi_SG_wo
france is laaaaame


Recognized by the Official EG/GG&A Who To Listen To List 2009
#20
It may be that the power is so low that burning up the output transformer is not a concern. When it comes to tube amps it's best to follow the manufacture recommendations. However, you never know if some document writer just did a cut and paste from another manual.
#21
^ true stuff - well it's no problem in my case really, if i ever get a cab for it i'd make a 2x10 and just get 2 8ohm speakers, but still, made me wonder


Whodicted



Quote by stevo_epi_SG_wo
france is laaaaame


Recognized by the Official EG/GG&A Who To Listen To List 2009
#22
Here is some hard evidence that the way round I stated is correct, just to clear this up:

CustomerService@peavey.com wrote:

Hello Lee,

The amp is designed to use a 16 ohm speaker, and that is what is
recommended.
You can use an 8 ohm speaker, but the amp will run a little hotter and your
headroom will be reduced, along with slightly reduced tube life.


Regards,
Roger Crimm
Regional Service Manager
Peavey Electronics

----

Lee Simpson

rnet.com> To
customerservice@peavey.com
03/20/2008 01:58 cc
AM
Subject
Peavey ValveKing 112 Speaker
Replacement (8Ohms)

Hello,

I have recently replaced my Valveking 112 Combo's speaker with a Celestion
Vintage 30. I have accidentally bought the 8 Ohm version and fitted it
without realising that the amp is in fact rated at 16 Ohms. I've been using
it at low to moderate volumes over the last few weeks (the loudest it's
been is 5-6 when I broke the speaker in), and nothing's gone wrong. However
I'm a bit worried about it and would like to know if there are any
consequences to this, or if it would damage my amp.

Thanks very much for any help you can offer,

Lee Simpson

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