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Topic: What happens if you use an 8ohm speaker for one side of 115? |
Scott Denniston
From:
Hahns Peak, Colorado, USA
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Posted 30 Jul 2021 2:53 pm |
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| The Peavey Session 115 is a stereo capable amp but it's unclear to me if each side has an independent power amp. The speaker in it is a 15" 4ohm. I'm wondering if adding a 12" 8ohm as an extension speaker instead of 4ohm for the other stereo side would degrade the sound or power from the 15" 4ohm. |
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Tony Prior
From:
Charlotte NC
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Posted 31 Jul 2021 1:39 am
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The specs state,( manual) when using a single speaker use the mono side speaker output when using 2 speakers( 4 ohms or greater) use the stereo out.
_________________
Emmons L-II , Fender Telecasters, B-Benders
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Scott Denniston
From:
Hahns Peak, Colorado, USA
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Posted 31 Jul 2021 6:47 am
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| Thanks Tony. But I mean using a single speaker would just be using the internal 15" 4 ohm. (not using any outs) If you wanted to add a speaker in stereo I know you'd use the stereo out but if that external speaker was 8ohms instead of 4ohms (like the internal speaker) would that somehow detract from the internal speaker by using a higher ohm external with it in stereo? I'm pretty ignorant about loads & ohms etc. and as mentioned it's unclear to me if the power amp is two channels or if it's two independent power amps. I mean if that would even make any difference. I'm toying with the idea of trying an Eminence TT 12 for an external in stereo but it's 8ohm. |
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Tony Prior
From:
Charlotte NC
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Posted 31 Jul 2021 10:30 am
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Scott, going higher typically is not an issue, going LOWER can be. When I read the PV specs for this amp I conclude that going to 8 is not a big deal with 2 speakers, one being 4 ohms. They state themselves 4 ohms or greater. Its possible that it is designed with some sort of buffer on the output.
These days many of the manufacturers just state - minimum 4 ohms for a combination of speakers. Meaning - don't go to 2 ohms ! 
I wouldn't worry about it.
_________________
Emmons L-II , Fender Telecasters, B-Benders
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Scott Denniston
From:
Hahns Peak, Colorado, USA
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Posted 31 Jul 2021 10:42 am
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| Thanks Tony. That'll be fun to play with. |
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b0b
From:
Cloverdale, CA, USA
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Scott Denniston
From:
Hahns Peak, Colorado, USA
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Posted 31 Jul 2021 2:17 pm
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| b0b wrote: |
| I’d expect the 4 ohm speaker to be louder. |
Well since there is no stereo balance or anything on that amp (that I'm aware of) maybe I'd go with the 4 ohm TT 15 instead. |
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b0b
From:
Cloverdale, CA, USA
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Tony Prior
From:
Charlotte NC
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Posted 1 Aug 2021 1:30 am
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| b0b wrote: |
| I’d expect the 4 ohm speaker to be louder. |
Theoretically the 4 ohmer should be louder, but practically we would probably never be able to tell the difference. I've replaced many 4 ohm speakers with 8's over the years, I'm sure the "current" meter could tell the difference but my ears were immune to any differences !
This all gets back to that +10 db equation thing to notice a change.  
_________________
Emmons L-II , Fender Telecasters, B-Benders
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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George Biner
From:
Los Angeles, CA
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Posted 2 Aug 2021 2:34 pm
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The 4 ohm will definitely be louder, so I wouldn't recommend it. How much? Say just for kicks the amp is putting out 25Vrms (just a random number).
The power in a speaker is roughly V^2/R (voltage squared divided by resistance (from Ohm's law and the definition of resistance))
8 ohm: 25^2/8 = 78 watts
4 ohm: 25^2/4 = 156 watts
Edit: this is true for a very stiff output like a solid state amp -- for a tube amp, same general idea, but it's more complicated.
_________________
Guacamole Mafia - acoustic harmony duo
Electrical engineer / amp tech in West Los Angeles -- I fix Peaveys
"Now there is a snappy sounding instrument. That f****r really sings." - Jerry Garcia
Last edited by George Biner on 4 Aug 2021 8:53 am; edited 1 time in total |
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Jerry Overstreet
From:
Louisville Ky
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Posted 2 Aug 2021 4:42 pm
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I have no experience with this amp but unless I'm missing something, the problem running stereo with this amp and extension speaker is that there is no provision to balance the speakers seperately from the amp controls. I don't know that I've ever seen a stereo capable amp without volume controls for ea. side.
It appears that the system is built for use with the same 1501-4 speaker for ea. stereo side.
Also, the effects controls appear to be global and the parameters fixed. It wouldn't really be stereo but just a duplicate of side 1 for side 2 for a bigger sound.
If they were programmable, you would be able to go in and mix the volume of ea. speaker output inside the fx settings.
This would allow you to balance the speakers to your liking.
I wouldn't be afraid to mix 4 and 8 ohm speakers in a stereo config this way. I'd probably use an offboard multi-fx unit so I could control ea. side's volume and fx mix.
With the current setup, if you add an extension speaker of any other design than the original, you're stymied when it comes to adjustments it seems to me. You're stuck with what you got. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 2 Aug 2021 6:32 pm
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Contrary to what the experts and engineers may say, doubling the power makes an easily discernible difference down in the low frequency ranges (below 150 Hertz). But in the mid and higher ranges, they're right. A mere doubling of power probably wouldn't be noticed.
And now you know why the original 85-watt B/F Twin went to 100 watts, and then to 135 watts. Bass takes power, AKA watts, AKA amperage! And you also just discovered why there are many popular low-powered guitar amps, but not a lot of popular low-powered bass amps.  |
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Scott Denniston
From:
Hahns Peak, Colorado, USA
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Posted 3 Aug 2021 7:31 am
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"I wouldn't be afraid to mix 4 and 8 ohm speakers in a stereo config this way. I'd probably use an offboard multi-fx unit so I could control ea. side's volume and fx mix."
That's what I'm thinking Jerry. I might try it with my MPX1. If it doesn't work out I do have another use for the TT12. |
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