Fender "Evil Twin" Hi/Low output = same level

jl_lensman · 22nd April 2009, 02:55 PM

Hello all -

I've got a early 90s model of the Fender "Evil Twin" It works fine except that the Hi/Low switch does seem to change the output sound level at all. I have replaced the tubes all around and still no difference. Is there a problem internally with the amp or am I just misunderstanding what the function of the switch is for?

ethermion · 22nd April 2009, 04:06 PM

It is, and always will be, a loud amp. I have a '99. I doubt a problem with the switch.

The hi/low power switch flips between triode and pentode mode. It should make 10 seem like 9 on the volume. You can also (on mine at least) pull two of the output tubes - inside or outside pair - I don't remember which though it probably does not matter. If you pull two output tubes, there should be a toggle to change the speaker load. 4 ohms for 4 output tubes, 8 ohms for two output tubes. Something like that.

Low power enabled, and two power tubes pulled, should have you at approximately 15 watts. Problem is, that you are still driving 2x12" speakers. Ice pick in the ear is as ice pick in the ear does. If you want to reduce volume, just turn down. If you want to reduce volume and get some sort of creamy overdrive forget it. The only creamy overdrive you will get is the bones rattling in your head.

jjman · 22nd April 2009, 04:16 PM

I had an amp with the triode/pentode output switch. The only difference I could hear was a little less bass in triode mode.

vito · 24th April 2009, 02:21 PM

The hi/low power switch in the evil twin switches the H.T. supply to half and also lowers the bias voltage. These switches often arc internally and cause the H.T. to remain at full voltage while the bias is lowered resulting in a very hot amp and failure of the output valves. So if the amp doesnt sound any different at low power and its getting hot get the switch replaced.

bereanbill · 24th April 2009, 10:49 PM

I think the pentode/triode switch thing is an urban myth. I mean, you still have the supressor grid in the tube, right? I've never heard much difference no matter what amp it is...i.e. Carvin Nomad, Gibson Goldtone... I had a red knob "Evil Twin" and my solution was simple...get a different amp !!! To quote my Grandpa "You can't make chicken salad from chicken crap !"

22nd April 2009, 02:55 PM	#1
jl_lensman diyAudio Member Join Date: Apr 2009	Fender "Evil Twin" Hi/Low output = same level Hello all - I've got a early 90s model of the Fender "Evil Twin" It works fine except that the Hi/Low switch does seem to change the output sound level at all. I have replaced the tubes all around and still no difference. Is there a problem internally with the amp or am I just misunderstanding what the function of the switch is for?

22nd April 2009, 04:06 PM	#2
ethermion diyAudio Member Join Date: Apr 2005 Location: ffx station, va	It is, and always will be, a loud amp. I have a '99. I doubt a problem with the switch. The hi/low power switch flips between triode and pentode mode. It should make 10 seem like 9 on the volume. You can also (on mine at least) pull two of the output tubes - inside or outside pair - I don't remember which though it probably does not matter. If you pull two output tubes, there should be a toggle to change the speaker load. 4 ohms for 4 output tubes, 8 ohms for two output tubes. Something like that. Low power enabled, and two power tubes pulled, should have you at approximately 15 watts. Problem is, that you are still driving 2x12" speakers. Ice pick in the ear is as ice pick in the ear does. If you want to reduce volume, just turn down. If you want to reduce volume and get some sort of creamy overdrive forget it. The only creamy overdrive you will get is the bones rattling in your head. __________________ -e

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22nd April 2009, 04:16 PM	#3
jjman diyAudio Member Join Date: Jan 2009	I had an amp with the triode/pentode output switch. The only difference I could hear was a little less bass in triode mode.

24th April 2009, 02:21 PM	#4
vito diyAudio Member Join Date: Aug 2008	The hi/low power switch in the evil twin switches the H.T. supply to half and also lowers the bias voltage. These switches often arc internally and cause the H.T. to remain at full voltage while the bias is lowered resulting in a very hot amp and failure of the output valves. So if the amp doesnt sound any different at low power and its getting hot get the switch replaced.

24th April 2009, 10:49 PM	#5
bereanbill diyAudio Member Join Date: Jan 2009	I think the pentode/triode switch thing is an urban myth. I mean, you still have the supressor grid in the tube, right? I've never heard much difference no matter what amp it is...i.e. Carvin Nomad, Gibson Goldtone... I had a red knob "Evil Twin" and my solution was simple...get a different amp !!! To quote my Grandpa "You can't make chicken salad from chicken crap !"