Which ohm setting do you prefer on your amp?

[Joe L]

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.

8 ohms = less wire = less weight = faster, more accurate response in the high end. Not everyone likes this but if you do, go for it!!

..Joe L

 

[stephen sawall]

Depends on the amp and cabs I am using.

 

[tubortski]

Thanks Joe L

 

[thegame]

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.

What about running a matched 4 ohm load (4 ohm amp to 4 ohm cab) with EL34s ? Still bad ? Would the lesser, but matching, load wear the tubes faster ?

 

[blackba]

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.

What about running a matched 4 ohm load (4 ohm amp to 4 ohm cab) with EL34s ? Still bad ? Would the lesser, but matching, load wear the tubes faster ?

Matching the output transformer impedance to the speaker load like 4ohm output to 4ohm speaker cab load is always the safest, that is the design intent of the amplifier designer. When you start missmatching impedance you are always at more of a risk, it just depends on if the amp is robust enough to handle this abuse.

 

[thegame]

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.

8 ohms = less wire = less weight = faster, more accurate response in the high end. Not everyone likes this but if you do, go for it!!

..Joe L

I believe 8 ohm speakers have less, but thicker wire wrapped around the voicecoil. So I'm not sure its less wire overall. I do agree with the tonal assessment of 8 vs 16. Though neither is better because you can really fine tune the final icing on the cake this way. 16 ohm speakers won't automatically sound "fizzy" if the amp is inherently smooth IMO. Rather, they can add a bit more high end liveliness than 8 ohm ones do, depending on the speaker type and amp combination. 8 ohm speakers can take away a bit of fuzziness if the amp/speaker character is naturally bringing that out.

 

[thegame]

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.

What about running a matched 4 ohm load (4 ohm amp to 4 ohm cab) with EL34s ? Still bad ? Would the lesser, but matching, load wear the tubes faster ?

Matching the output transformer impedance to the speaker load like 4ohm output to 4ohm speaker cab load is always the safest, that is the design intent of the amplifier designer. When you start missmatching impedance you are always at more of a risk, it just depends on if the amp is robust enough to handle this abuse.

I know that, but my question was, is a 4 ohm matching load harder on the amp/tubes, than a matching 16 ohm load ?

 

[blackba]

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.

What about running a matched 4 ohm load (4 ohm amp to 4 ohm cab) with EL34s ? Still bad ? Would the lesser, but matching, load wear the tubes faster ?

Matching the output transformer impedance to the speaker load like 4ohm output to 4ohm speaker cab load is always the safest, that is the design intent of the amplifier designer. When you start missmatching impedance you are always at more of a risk, it just depends on if the amp is robust enough to handle this abuse.

I know that, but my question was, is a 4 ohm matching load harder on the amp/tubes, than a matching 16 ohm load ?

The 16ohm tap uses all the secondary windings on the output transformer, so it technically would be a little better for the transformer, but not by much.

I found this to be an interesting thread to read. https://www.thegearpage.net/board/showth ... p?t=917297

 

[rupe]

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.

I hear what you're saying, but I know several players who intentionally mismatch the 8 ohm setting on their heads with a 16ohm 4x12 and have had no issues with tubes damage. In fact, one friend still had the original tubes in a '76 50w head when he had it gone over for the first time '96. 20 years is a crazy amount of time for no tube failure on a heavily gigged amp...maybe he would have gotten 40 had he matched impedance
I think it's more about the overall design of the amp more than anything. My Matchless Chieftain will walk through a pair of EL34s in 2-3 months with heavy use...and that's with matched impedances (4 ohm, which I find odd but Phil Jameson explained that it's how those amps sound the best...a contradiction to the "use all the windings" mantra).

 

[modulo]

16 Ohms on my Marshall and 16 Ohms on my EVH 5153 III

Pascal

 

[aulo]

I tried running my Fortin at 8ohms and matching it at 8ohms with my Traynor cab (loaded with G12-T75's). It sounded good, but there was a little bit of high-end fizzle that I couldn't quite dial out. Now I run the amp and cab at 16ohms each and the Fortin is so much bigger sounding and any harshness that I heard before is gone.

Fat, fat, FAT!