Oh what a difference a speaker makes: 94db sensitivity versus 102db sensitivity (Princeton Reverb, Jensen, Cannabis Rex content)

[number008]

The TGP continues to be goldmine of new, useful information for me. I recently learned, from this forum, about the significance of speaker sensitivity to the tone and volume of an amp. Following suit from these lessons, I bought an extension cabinet with a Cannabis Rex speaker (102db sensitivity rating) and a speaker cable for a grand total of $120 bucks. The difference is truly amazing. I'm either woefully under-informed about the physics of amplification or perhaps it's just not common knowledge (likely both), but the impact to the sonic profile just blows me away.

So, what did I learn from this forum: A more efficient (or less sensitive) speaker will have less headroom, less volume and perhaps more character at lower volumes. Meanwhile, a less efficient (more sensitive) speaker will be louder with more headroom and more clarity even at higher volumes. I read that for every additional +3db of sensitivity, one could expect double (?, need to verify) the volume.

What did I do: The first plan was to replace the Jensen p12q (94db) in my Princeton '65 Reissue Reverb (15w) with a Cannabis Rex speaker (102db); that would cost me about $90 but I would lose any optionality should I want to go back to the Jensen sound (for harmonica, for example). Then I thought about buying another Princeton Reverb '65 Reissue (15w, 12") to match my own except with a Cannabis Rex speaker already installed; that would give me stereo optionality on top of the sound I was looking for, but that's the expensive option ($900). Ultimately, thanks to good luck, I found a local deal where a guy was selling an extension cabinet with a CRex already installed ($100). I bought that and plugged it in; now I have the sound I wanted and optionality, no stereo though (can't have everything).

I couldn't recommend this approach more. I'm sure I'm late to the party with this information but wow is this a time and money saver, and it could even work in reverse if you are looking for attenuation.

[Caveat: For Princetons, you should unplug the main speaker and connect the extension; best to avoid plugging the extension cabinet into the extension port. The reason, I learned, you shouldn't plug an 8 ohm speaker into the extension jack is that the total ohms for the transformer should be 8 on a Princeton; if you plug into the extension you will have 4 ohms running through the transformer. You need to either unplug the main speaker (which is what I did) or replace the main speaker with a 16 ohm speaker and get an extension cabinet with a 16 ohm speaker, so that you are running 8 total ohms through the transformer.]

 

[Tricerapotamus]

You have it backwards though... efficiency is proportional to sensitivity.

I usually opt for a less efficient/sensitive speaker because I'm trying to tame a high wattage amp. I'm using WGS Veteran 10's (93.8 dB) in my Super Reverb, for example. For a Princeton and low wattage amps I'd want the higher sensitivity speaker though.

 

[number008]

Did you always know about the dynamic relationship here? Put differently, is this common knowledge and I am just uneducated?

I ask because I did A LOT of fiddling/buying/tone-hunting before discovering this. The Princeton sound is what I like but I sometimes want it low and dirty, and sometimes I want it loud and clean. Until now, I had a hard time finding that without fiddling with pedals. (I still use pedals, just to be clear.)

 

[teemuk]

I read that for every additional +3db of sensitivity, one could expect double (?, need to verify) the volume.

Nope. Unfortunately +3 dB is only a subtle increase in perceived loudness ...BUT... if you would try to achieve that +3dB by increasing the output power you would have to double the output power.

e.g. speaker rated 100 dB @ 1W will produce 103 dB at 2W, 106 dB at 4W, 109 dB at 8W, 112 dB at 16W, and so on.

You need approximately tenfold increase in output power to generate a 10 dB increase in sound pressure level, which approximately equals doubling perceived loudness. (In practice psychoacoustics are not as straightforward)

Upgrade from 94 dB to 102 dB is 8 dB increase so you basically need less than 1/4 th of the initial power to produce equivalent sound pressure levels. Or let's put it this way; your amp now sounds more than four times as powerful as before the speaker upgrade. So yes, it certainly will make a difference.

 

[madhermit]

+3dB is not double the volume.

1 bel (or 10 decibels) is double the perceived volume. A decibel (dB) is 1/10 of a bel. +3dB take double the power to accomplish and is considered the smallest volume change most regular people can hear.

So to get a small change in volume, you need to double the Watts of an amp. (eg 10 Watts to 20 Watts)
To double the volume of an amp, you need 10x the Watts. (eg 10 Watts to 100 Watts).
This assumes nothing else changes, i.e. the speaker, number of speakers, etc.

Way too many people on forums confuse 3dB with double volume. It is not.

Also, the decibel scale is not linear.

 

[Gallery]

Or you could drop a grand on a Fluxtone and have a speaker that can be dialed to any efficiency you want.

 

[madhermit]

Did you always know about the dynamic relationship here? Put differently, is this common knowledge and I am just uneducated?

I ask because I did A LOT of fiddling/buying/tone-hunting before discovering this. The Princeton sound is what I like but I sometimes want it low and dirty, and sometimes I want it loud and clean. Until now, I had a hard time finding that without fiddling with pedals. (I still use pedals, just to be clear.)

See the replies just after your question. There are many factors, but that is the main jist.

MANY people mess it up and then spread it on the forums. It is not common knowledge in opinion, as so many people get it wrong.

People really misunderstand Watts and decibels.

 

[madhermit]

Or you could drop a grand on a Fluxtone and have a speaker that can be dialed to any efficiency you want.

I have one of the Eminence speakers called a Maverick that has a moveable magnet. Dialing it away lowers the efficiency by up to 9dB, so close to half volume. Very cool in my Princeton.

From what I understand, they can add it to any speaker with the same size magnet if you contact them. It’s called FDM.

 

[number008]

Re: +3db = double volume. Sorry, I really did mean +3db would garner an increase in volume equal to that of an amp with double the Watts. (I realize I came nowhere close to saying that though.)

 

[Luke V]

So, what did I learn from this forum: A more efficient (or less sensitive) speaker will have less headroom, less volume and perhaps more character at lower volumes. Meanwhile, a less efficient (more sensitive) speaker will be louder with more headroom and more clarity even at higher volumes. I read that for every additional +3db of sensitivity, one could expect double (?, need to verify) the volume.

No, as mentioned above, more efficient equals more sensitivity.

 

[Gallery]

I have one of the Eminence speakers called a Maverick that has a moveable magnet. Dialing it away lowers the efficiency by up to 9dB, so close to half volume. Very cool in my Princeton.

From what I understand, they can add it to any speaker with the same size magnet if you contact them. It’s called FDM.

Yeah I have the same speaker. I have both actually. The Eminence is an awesome option for gig'ing with a non-master volume amp. At least that is how I used it. I use my Fluxtone at home since it dials down to almost zero. For the life of me I can't understand why the Eminence FDM tech hasn't taken off. No attenuator to carry around and it cuts enough volume for a gig'ing musician to appease the house.

 

[number008]

I have one of the Eminence speakers called a Maverick that has a moveable magnet. Dialing it away lowers the efficiency by up to 9dB, so close to half volume. Very cool in my Princeton.

From what I understand, they can add it to any speaker with the same size magnet if you contact them. It’s called FDM.

Now that's pretty damn cool. I'm going to look that up now. Among many other practical uses, wouldn't this more easily achieve what people using attenuators are looking for? Perhaps less damaging to the amp as well?

EDIT: Both the Maverick and Reignmaker models are seemingly gone from the Eminence website. You can search for them and get links to some information about them, but they are not there to be selected (at least, I can't find them.) I wonder what happened?

 

[Auditory Driving]

I was asking about those speakers on tgp recently as well, i think that they were a bit ahead of their times - they might have been much more popular nowadays

 

[Tricerapotamus]

Did you always know about the dynamic relationship here? Put differently, is this common knowledge and I am just uneducated?

I ask because I did A LOT of fiddling/buying/tone-hunting before discovering this. The Princeton sound is what I like but I sometimes want it low and dirty, and sometimes I want it loud and clean. Until now, I had a hard time finding that without fiddling with pedals. (I still use pedals, just to be clear.)

I just figured it out by trial and error a couple of years ago... I bought a low efficiency Jensen alnico speaker replacement and couldn't believe the difference. One other thing to consider is that low efficiency speakers have a natural compression built-in to their design because it takes more electromagnetic "push" before they'll respond. I'm sure you heard it yourself with that Jensen. Alnico magnets also have their own form of compression, and the combination of the two is what makes people covet them. That p12q in your Princeton should have been a great, classic-sounding combination.

 

[zenas]

EDIT: Both the Maverick and Reignmaker models are seemingly gone from the Eminence website. You can search for them and get links to some information about them, but they are not there to be selected (at least, I can't find them.) I wonder what happened?

It's my understanding they stopped making the FDM speakers. I blame that on poor marketing. Had a Maverick in a Deluxe Reverb it was great for gigging and being able to turn the amp up to warm up lower volume cleans. But it didn't drop volume enough for cranking the snot out of the amp at "bedroom volume". I've always said it's like a master volume that only goes down to 5.
I think a lot of guys though they could get cranked amp tones at bedroom/apartment volumes and they were disappointed. What do we do when we're disappointed? We go on the internet and slam the product!
I believe Eminence could have done a better job of explaining exactly what they were good for, and they work great for what they do! But aren't an attenuator in the sense that you can get down to mouse fart volume with a cranked amp. Really the "mouse fart volume crowd" is a huge segment of the market today, and a lot of players are completely in the dark about speaker sensitivity.

 

[number008]

That p12q in your Princeton should have been a great, classic-sounding combination.

You're right, it sure is. That's the beauty of the solution I found; I can switch back and forth from the Jensen to the CRex by simply pulling one jack and putting the other in like an old-school telephone switchboard operator.

I wonder: Is there a stomp-box application that would allow me to connect both speakers but power only one, and then swtich back and forth between them?

 

[Auditory Driving]

Low volume playing is not necessarily by choice, unfortunately

 

[macrossgeorge]

Speaker changes can make massive tonal changes to an amp. It is well worth trying out different speakers. And also break in should be considered as well. I discovered that I really prefer alnico speakers to ceramic with my amps and since I am going for loud and clean I prefer efficient high sensitivity speakers too. After trying a bunch of speakers I have dialed in my tone. It was worth the journey and the costs.

 

[Rod]

You just can’t beat the tone of hemp cones...
Tone Tubby makes great Alnico and ceramic versions. I use their original Red Alnicos
Weber can build many of their speakers with hemp cones. I have a G-65 hemp and love it in my Juke.
Eminence makes 10” and 12” versions of their Cannibis Rex. I use both of these as well..
all great sounding speakers

 

[madhermit]

Now that's pretty damn cool. I'm going to look that up now. Among many other practical uses, wouldn't this more easily achieve what people using attenuators are looking for? Perhaps less damaging to the amp as well?

EDIT: Both the Maverick and Reignmaker models are seemingly gone from the Eminence website. You can search for them and get links to some information about them, but they are not there to be selected (at least, I can't find them.) I wonder what happened?

I think just low sales. People didn’t get it. I love mine. Had a Reignmaker I regret selling off in a Tweed Deluxe clone.