Which ohm setting do you prefer on your amp?

[Stramm8]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

 

[Shark Diver]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

Well I'm screwed then,

 

[LP Freak]

so I run 8 ohm from amp into my cabs as they are either 16 or 8 ohms that is ok right:???

No....the cabinet needs to match the ohm of the head or be higher.

 

[modulo]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

+1

 

[Michi]

I've not even thought about tonal differences, I've just gone with matching the cab's ohms with the amp. Given that I've used only Marshall 1960 in mono, it's always been 16 .

 

[rlord1974]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

Well I'm screwed then,

Seems like you're leaving some "tone on the table", David.

 

[Greazygeo]

Mostly mis matched for me.....amp set on 8 ohms into a single 16 ohm cab. My Hiwatt and Wizard are normally set matched to the cab though.

 

[Shark Diver]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

Well I'm screwed then,

Seems like you're leaving some "tone on the table", David.

This is why I never get anywhere

 

[Joe L]

I performed a little test when I bought my 5150 III 50 watt. It has 16/8/4 ohm taps and when set at 16 ohms through a 16 ohm cab the sound was noticeably "bigger", "fuller", "louder". It sounded so good that I sold my beloved Mesa 2x12 cab within a few days. According to Howard Kaplan at EVH, when you set the amp at 16 ohms and run it through a 16 ohm cab the amp is utilizing all of the winding in the transformer which translates to a better/different tone. I'm a believer...

Some amps/transformers will sound different due to this. A lot of it is dependent on whether the amp uses negative feedback which tends to cancel out effects of the load and the sound the output tubes and transformer bring to the table. I'm assuming that the 5150 III uses a clean power amp section which means a fair amount of feedback.

I will sometimes disconnect the negative feedback when testing different output tubes just for this reason. It allows the differences to be heard much easier.

Also, at higher impedance settings even if the load is correctly matched, the damping factor will be higher which means the amp won't be able to control the movement of the speaker as well. This will show up as a looser low end. So if you are set at 4 ohms with a 4 ohm stack, and it is too tight sounding, 16/16 just might loosen things up just right for your taste.

I wouldn't mismatch EL34s by putting a higher impedance cab on a lower impedance amp setting. If you push it hard, the screens are going to be overstressed and will likely blow the tubes.

..Joe L

 

[petejt]

I prefer 8ohms, but I've been running 8ohm into 16 ohm cabs without a hitch.

 

[glassjaw7]

so I run 8 ohm from amp into my cabs as they are either 16 or 8 ohms that is ok right:???

No....the cabinet needs to match the ohm of the head or be higher.

That's what he said. 8 ohm out from amp to 8 or 16 ohm cab. This is correct.

 

[LP Freak]

so I run 8 ohm from amp into my cabs as they are either 16 or 8 ohms that is ok right:???

No....the cabinet needs to match the ohm of the head or be higher.

That's what he said. 8 ohm out from amp to 8 or 16 ohm cab. This is correct.

Yea, I had to reread it.

 

[Joe L]

so I run 8 ohm from amp into my cabs as they are either 16 or 8 ohms that is ok right:???

No....the cabinet needs to match the ohm of the head or be higher.

That's what he said. 8 ohm out from amp to 8 or 16 ohm cab. This is correct.

Yea, I had to reread it.

Again, if you are running EL34s, it is not safe to have the cabinet at a higher impedance than what the amp is set to IF you are pushing the power section into distortion. Just look at the power tubes when you are playing at your highest volume/gain and see if there is a bright glow that appears near the center/core of the power tubes as you strum some power chords. That is the screen and it will melt and short out the tube if it overheats. Red is ok, yellow is really pushing it and white is gonna fail.

Note that this is different than "redplating" which is a dull red glow on the large solid outside element of the tube.

..Joe L

 

[AndyK]

I sold several sets of 16 ohm Greenbacks before getting my current 8 ohm set. At 8 ohms, the highs are less harsh. Works for me!

 

[satannica]

I go for 4 ohm myself. I used to go for 16 all the time, but 4 just seems to sound more open.

 

[petejt]

I go for 4 ohm myself. I used to go for 16 all the time, but 4 just seems to sound more open.

What about 4ohm tap from the amp, into a 16 ohm speaker load?

 

[blackba]

With my Marshall 2553, I prefer the 16ohm setting, but that is also the 2 speakers in series versus the 4ohm setting which is the 2 speakers in parallel, so there is more than just the tap on the transformer in play. With other amps, I hear less difference.

 

[tubortski]

I go for 4 ohm myself. I used to go for 16 all the time, but 4 just seems to sound more open.

What about 4ohm tap from the amp, into a 16 ohm speaker load?

I don't think this is safe. You run the risk of damaging something.

4 to 8 is fine. 8 to 16 is fine.

Hopefully another RT member will chime in with more details.

 

[Joe L]

I think I've already pointed this out but for an amp using EL34s with a typical output section, running a lower impedance setting on the amp than the speaker load is bad. What happens is when you overdrive the outputs it causes very high current in the screen grids. They can and WILL melt and when they do it can take out the output transformer.

It is easy to see for yourself. Take off the back panel and slowly start cranking the master as you play. When you get up pretty loud you will see a glow in the center of the tube within a second or two after hitting and holding a power chord. It will go away almost immediately when you stop playing. Red is ok, Orange is still ok, Yellow is pushing it and White is about to blow.

Different tube designs will tolerate more or less screen current. The best test is what I described above. Mark a setting on your Master where the are just starting to glow yellow and never go over that.

Note, I'm talking about the screens, which are thin wires inside the Plates which are the large outside elements of the tube structure. Also not to be confused with the filaments which are at the very center and always glow a nice orange.

 

[EyesOfTheSouth]

I sold several sets of 16 ohm Greenbacks before getting my current 8 ohm set. At 8 ohms, the highs are less harsh. Works for me!

Exactly. An amp builder told me this one time and honestly I didn't believe it. However, I have extensively A/B'd same model speakers in different ohms. 8 ohm speakers are more focused overall and warmer on the high end with less "fizzies". I wire all my cabs with 8 ohm speakers now.......4x12's at 8 ohm mono and 2x12's at 16 ohm mono.