Question about speaker wattage.

[PeteMac]

I'm thinking of upgrading the speaker in my HRDlx to a JensenC12. The "N" is rated at 50w and the "Q" is rated at 35 watts. I'm wondering what the difference between the two would be in my amp.
I know from the hi-fi world that it's better to slightly under-do the power rating of the speaker compared to the amp so as to avoid a lower powered amp working too hard and thus produce distortion (the yukky kind!). Does this hold true in guitar amps, or is it a different kettle of fish? ... In other words would the lower rated speaker be more sensitive and perhaps better sounding in my 40w amp?

[tjalla]

Yes, it works the other way around in guitar amps... in almost all cases the speakers are rated higher than the amps output... just so that when you *do* crank the amp (cause we guitars gotta overdrive things, yea?), the speaker will hold up.

Another reason I'd get the C12N is that tonally, it'll tame the high in a HRDlx, which I find can get shrill. The C12Q is already a bright speaker, so I'd steer away from that one...

One of the few amps that come with matching speaker and output power is a Vox AC30 with 2x15w Celestion Blues ie 30w amp, 30w combined speaker power handling. Pretty risky if you crank the amp, as them Blues aren't easy on the wallet...

Also, sensitivity isn't *always* equated with a lower rated speaker. While the 15w Celestion Blue [i]is[i\] a very efficient speaker, a 15w Jensen P12R isn't.

Hope this helps!

Trevor

[PeteMac]

Thanks Trevor,

That clears things up a bit.

Now I just need to know If changing the speaker first or the power tubes is going to give me more clean headroom ... (I need to do my upgrades in stages, due to budget restrictions!) I am right in assuming my clean headroom will come from the power tubes aren't I???

Thanks again

[tjalla]

[quote="PeteMac"]I am right in assuming my clean headroom will come from the power tubes aren't I???/quote]

I wouldn't immediately assume that. Perhaps if your tubes are on their way out, then yes. Otherwise a speaker change can make a bigger difference, IMO.

That said, if you really want maximum headroom over the stock speaker, I'll look at something like the Weber California, rather than a C12N.

Trevor

ps sorry for the ghastly spelling in my earlier post!

[Wally]

Originally Posted by PeteMac

I'm thinking of upgrading the speaker in my HRDlx to a JensenC12. The "N" is rated at 50w and the "Q" is rated at 35 watts. I'm wondering what the difference between the two would be in my amp.
I know from the hi-fi world that it's better to slightly under-do the power rating of the speaker compared to the amp so as to avoid a lower powered amp working too hard and thus produce distortion (the yukky kind!). Does this hold true in guitar amps, or is it a different kettle of fish? ... In other words would the lower rated speaker be more sensitive and perhaps better sounding in my 40w amp?

Pete, when I was trying to read and understand hi-fi musical reproduction equipment before laying out some bucks for a good system back in the early '70's, the prevailing logic was to buy speakers that had at least a 25% excess of wattage handling ability compared to the amp with which they were to be used. IMHO, there is nothing about a higher wattage speaker combined with a lower wattage amp that creates a necessity for the amp to 'work harder'. That is a new one on me.
As to your guitar amp/speaker, isn't that a 60 watt amp? I have always applied what I learned about hi-fi speakers to musical instrument speakers. I always provide more wattage handling ability in the speaker than the amp can produce, especially when looking for headroom. I would be looking for an 80-whatever above 80 watt speaker. A Weber Michigan ceramic with paper dust cover is Ted's version of an EV and will reproduce whatever the amp is doing without coloring the sound...as would a real EV if you had one handy to go in that amp. Just some thoughts...

[tjalla]

The Deluxes are 1x12" 40watters, its the 4x10 and 2x12 Devilles that are rated at 60w.

I'd concur re Weber Michigan, they are Weber's "big headroom" model. I haven't used one personally, but from what I gather, it should further tame the high end, too.

Trevor

[Wally]

40 watts...a 50 watt speaker would handle things. An Eminence Legend GB128 would work well in that amp, I would think. They are high-efficiency so as to maximize what headroom the amp does have. The GB128 has a big bottom with warm highs....some woody tone to my ear. It would warm that HRD up some and yield good headroom. The WEber Michigan ceramic would assure that the amp could be pushed as far as one wanted or had to.

[NTC]

An amplifier's rated power output is usually for an UNDISTORTED output - right before the amplifier starts to distort. When distortion occurs, the amount of power dissipated in the load can still go up - the signal spends more and more time at its limits. If you are somebody who likes to run their amps on 11 (or even 7 for many amps), a speaker probably should be rated for 20% -25% the rated output power of the amplifier.

[Wally]

Originally Posted by NTC

An amplifier's rated power output is usually for an UNDISTORTED output - right before the amplifier starts to distort. When distortion occurs, the amount of power dissipated in the load can still go up - the signal spends more and more time at its limits. If you are somebody who likes to run their amps on 11 (or even 7 for many amps), a speaker probably should be rated for 20% -25% the rated output power of the amplifier.

"20-25% the rated".....do you mean 20-25% ABOVE
the rated output?
And...when we run our amps at that limit plus use OD's and fuzz boxes, we keep those cones at max excursion. Heat dissipation becomes a concern. Even low wattage amps can burn down a large wattage speaker when run in this manner. I've read that the EV's in J. Hendrix' Marshall cabs got overhauled regularly.

[JohnnyCrash]

PeteMac,

Impedance mismatches on the output transformer are more dangerous for it than a speaker's power handling... especially on how much it has to "work" or not.

Lower power ratings on the speaker are more dangerous for the speaker.

When it comes to guitar speakers, higher ratings are best for speaker life/safety. 125% to 150% of the amp's power is a good start... but some folks like to cut it a little closer for "speaker breakup".

Celestion Blues are a pretty durable set of speakers, and alot of VoxAC30 owners are notorious for liking to crank those amps. There are a few speakers that are pretty tough, but most folks don't like gambling with good money on speakers.

[PeteMac]

Thank you all for the information.

Yes, I remember reading elsewhere about "over-rating" speakers for guitar amps. It makes sense.

I'll look into the Webers and the Eminence (although it's an Eminence Legend 125 that's in it now.)

Thanks again