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

WillLane

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2,033
now that we're past all that technical talk Speaker sensitivity is huge. I replaced the Ten 30's (95 dB) in my '68 Custom Vibrolux with Ragin Cajuns (100 dB), now it's a mini Twin. Glassy, smooth, loud, percussive; like a traditional Fender amp should be.

Just tonight, I replaced the second G12M with an Alnico Gold in my 2000 AC30TB, so now it has a Gold and a Blue. Even with just a 2 dB increase, it's noticeable and the amp is truly magic. Had me giggling like the first time I ever played a TBX.

This isn't to say lower sensitivity speakers are bad. I just wonder why Fender still continues to put low sensitivity speakers in their amps while extremely similar but higher sensitivity speakers exist.

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.
Between the Cannabis Rex and the P12Q, I wouldn't worry too much about having access to both options at any time. You're still in the same ballpark, which is important; it's not like you're swapping between a Jensen and a Greenback, for example.
 

HotBluePlates

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10,654
SEMANTICS WARNING:

Sensitivity: Decibels SPL for 1 watt of applied power; how readily a speaker converts electrical power into sound pressure.​
Efficiency: How much of the applied power gets converted to sound (instead of being wasted as heat).​

I've made the mistake of saying "102dB speakers" are "very efficient." It is true that more-efficient speakers are also more-sensitive (get louder for the same applied power).

But speakers are horribly inefficient: Most convert less than 10% of the applied power into sound waves.

So it's not wrong to say more-efficient speakers are louder, but it's more-right to talk say these speakers are more-sensitive. Because all speakers are inefficient.
 
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HotBluePlates

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10,654
I never understand why they don't make a low db number ... like an 88 db green back. I guess some tech reason
I know almost nothing about speaker design.

That said, I suspect a sonic difference occurs when you make the magnet (or its magnetic force) smaller. Kinda like the difference between a G12H vs a G12M if everything other than the magnet is the same (which I am not sure is the case between those speakers).

I guess Eminence's approach (a movable magnet to make the speaker less-sensitive) didn't sell well enough to keep in the lineup. And Fluxtone's approach (replace the magnet with an electro-magnet + power supply; turn down power supply to make the speaker less-sensitive) seems cost-prohibitive for wide adoption.
 

Rotten

Gold Supporting Member
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6,258
Like most things on TGP, I've learned a ton by reading threads. However, more than any other guitar or amp component, I've found the writings mostly useless. I've played speakers that I thought were too bright where much of the consensus was that they are too dark. I think it comes down to playing technique, hearing, and maybe pickups. The good news is that I found a relatively inexpensive cure for G.A.S. by rolling speakers. Buy used and sell used. In the OP's case, with the extra cab you could compare fairly easily. Great fun!
 

zenas

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8,759
Oxford 12in speakers, from what I've read on the internet, dropped in sensitivity about 1965. As I understand it, they opened the voice coil gap up which reduced the sensitivity and made them stand up better in things like Twin Reverbs. Wasn't really that popular with people at the time because back then they played louder.
If it's really that simple you'd think one of the manufacturers would offer "wide gaps" as an option today. Of course speaker baskets and magnetic parts are often outsourced, so it'd be an extra expense in the process.
If I had a turning lathe, it'd be an interesting experiment to try on some less valuable speakers, with readily available soft parts of course.
 
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HeavyCream

Silver Supporting Member
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3,719
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.
It’s too bad they stopped making the FDM speakers. I think you’re right, Eminence could have done a better job pumping them up. IMO, another reason they didn’t sell too well is because they’re thought of as sort of generic US/Brit speakers. I wonder why they didn’t offer the FDM tech on some of they’re best selling speakers. Ragin Cajun, Cannibis Rex, Legend, Wizard, Private Jack...

When they came out you had players wondering about the FDM and how well it works, and wondering about the speakers themselves and how good they sound. That’s the reason I didn’t pull the trigger when I was considering one anyway. What is the Maverick? Is it a Patriot? Is it it’s own thing? I definitely agree they didn’t push them hard enough by educating folks on how thy work, but I think they would of been better off adding FDM to a couple speakers from their line rather new US and Brit speakers no one ever heard of.
 

Tone_Terrific

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33,020
I general the effect of speakers on volume and tone has been very well known by players forever.
Upgrade speakers were widely available in the '60s and anyone plugging into various cabs would immediately note a change.
 

ruger9

Silver Supporting Member
Messages
9,356
It’s too bad they stopped making the FDM speakers. I think you’re right, Eminence could have done a better job pumping them up. IMO, another reason they didn’t sell too well is because they’re thought of as sort of generic US/Brit speakers. I wonder why they didn’t offer the FDM tech on some of they’re best selling speakers. Ragin Cajun, Cannibis Rex, Legend, Wizard, Private Jack...

When they came out you had players wondering about the FDM and how well it works, and wondering about the speakers themselves and how good they sound. That’s the reason I didn’t pull the trigger when I was considering one anyway. What is the Maverick? Is it a Patriot? Is it it’s own thing? I definitely agree they didn’t push them hard enough by educating folks on how thy work, but I think they would of been better off adding FDM to a couple speakers from their line rather new US and Brit speakers no one ever heard of.
+1. I feel like the FDM Eminence speakers came... and went. I think I only read 2-3 reviews online (on forums). Bottom line is, they didn't sell... but reports are they WORKED. So ??? Maybe they just didn't push them hard enough? Maybe they SHOULD have made the first models with one of their most popular speakers like the C-Rex?

Interesting that (as reported above) they will put FDM on any speaker you order from them...
 

number008

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Messages
125
Radial Cabbone - the company still exists and is making/selling similar products but this particular one is discontinued. That gives me pause, you know? Makes me think there was something wrong with it.
 

LaXu

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6,602
I know almost nothing about speaker design.

That said, I suspect a sonic difference occurs when you make the magnet (or its magnetic force) smaller. Kinda like the difference between a G12H vs a G12M if everything other than the magnet is the same (which I am not sure is the case between those speakers).

I guess Eminence's approach (a movable magnet to make the speaker less-sensitive) didn't sell well enough to keep in the lineup. And Fluxtone's approach (replace the magnet with an electro-magnet + power supply; turn down power supply to make the speaker less-sensitive) seems cost-prohibitive for wide adoption.
Fluxtone afaik has a patent on their tech so Eminence's approach is a less effective, budget version of that where it does not infringe on patents. I blame the lack of its success purely on Eminence marketing, almost nobody knows they even exist and they were basically just two speakers in their lineup where you can't even tell that they have a feature like this just by browsing the website.

The Eminence Maverick by all means works well, it's a different compromise to using an attenuator where it does change the tone but that can be compensated with amp controls easily. I'd say it would be best paired with amps that are on the bright side that you want to tame a bit. Fender or Vox combos would be a good candidate.

Using them in a cab with more than one speaker would get tricky as you would need to adjust each speaker separately. I don't know if Fluxtone has some solution to this where one control unit handles multiple speakers but at their current ridiculously high pricing you have to be very flush with cash to consider ordering say speakers for a 4x12 from them.
 

timmytVA

Gold Supporting Member
Messages
1,372
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?
https://www.radialeng.com/product/cabbone-ex (Discontinued, but might be able to find on Reverb)

Tim
 

Daytona57

Member
Messages
2,207
This is a technical review of the Cannabis Rex from TDPRI.com Jul 8, 2008#29
Stewart WardBanned
Having a peek at the published specs for the Eminence CR reveals that this speaker has a huge free air resonance (Fs) at about 97Hz (about G on the 6th string). Typically guitar speakers are around 75 to 80Hz. This would account for it's 'warmer' tonality when used in a smallish open back cabinet of a valve amp or a modern solid state amp with Frequency Dependent Damping (FDD is quite normal these days and mimics a tube output transformer's effects accurately).
The drawback being, is that you can't turn off or dial out this resonance if it 'get's in the way' for certain styles of music. E.G, the early Larry Carlton Mesa/335/Crusaders sound relied on the Electrovoice EVM12L with a low FS of 55Hz (designed as a PA mid range speaker) for that 'flat' tone which resulted... if that's what you like that is. So this speaker would be hopeless for this kind of sound.

The nominal impedance is in fact 7.5 ohms @ 300Hz This rises to around 120 ohms at Fs. There is also in interesting drop in output (a notch) at 1.5kHz, which would give the sound a kind of 'early Marshall' character. Dipping output at 1.2 to 1.8kHz with a narrow notch filter is a favourite trick of mine for re-creating early Marshall/Clapton/Tele/Mayal era sounds. So that would stack up for me.

All in all, on paper (or should that be hemp), a very interesting speaker and I shall obtain one and give it a good workout... shame it's only 50 watts though.

This just goes to underline how important the speaker and output transformer design is in the outcome of the sound your hear. Contrary to popular beliefs, it's NOT just about valves/tubes!! That 'Fender' amp tonality is mainly due to the output transformer desgns... IMHO according to my research (which is not for publication).
 

Dontchaknow

Member
Messages
81
+1. I feel like the FDM Eminence speakers came... and went. I think I only read 2-3 reviews online (on forums). Bottom line is, they didn't sell... but reports are they WORKED. So ??? Maybe they just didn't push them hard enough? Maybe they SHOULD have made the first models with one of their most popular speakers like the C-Rex?

Interesting that (as reported above) they will put FDM on any speaker you order from them...
The Maverick is awesome, and besides the function, it is just a great sounding speaker. I don't know why they weren't more popular, my thought is anytime guys hear attenuation, they think bedroom volume, which the Maverick does not do. For being able to get a deluxe reverb type that sounds thin below a certain point on the volume knob into a sweet spot at lower volume (but not quiet) situations and then be able to hang with a good, sensitive ceramic speaker at the simple twist of a dial, i have not found a better sounding and performing solution.
 

teemuk

Member
Messages
3,178
Poor man's fluxtone would be acquiring a field coil speaker (heads up if you own a very vintage amp with one) and a variable power supply for magnetising the coil. Eminence system is purely mechanic.
 

Steppin' Wolfe

Silver Supporting Member
Messages
5,057
Oxford 12in speakers, from what I've read on the internet, dropped in sensitivity about 1965. As I understand it, they opened the voice coil gap up which reduced the sensitivity and made them stand up better in things like Twin Reverbs. Wasn't really that popular with people at the time because back then they played louder.
If it's really that simple you'd think one of the manufacturers would offer "wide gaps" as an option today. Of course speaker baskets and magnetic parts are often outsourced, so I'd be an extra expense in the process.
If I had a turning lathe, it'd be an interesting experiment to try on some less valuable speakers, with readily available soft parts of course.
RE: wide gap, low efficiency Oxfords.....these were introduced in 1966 Not 1965.
 

Steppin' Wolfe

Silver Supporting Member
Messages
5,057
Poor man's fluxtone would be acquiring a field coil speaker (heads up if you own a very vintage amp with one) and a variable power supply for magnetising the coil. Eminence system is purely mechanic.
Teemuk, that is interesting. I have a beautiful Jensen F10 in great condition. It came out of an organ. I also have a 12” field could that needs a recone. I had never considered this path.
 

zenas

Member
Messages
8,759
A couple reasons Fluxtones cost so much, not that I'm an expert, just common sense.
They start with an existing speaker and modify it. Right off the bat they're paying more for a speaker than a manufacturer that buys the basket assembly and soft parts wholesale and glues it all together. Then they have to pull off the magnetic speaker motor and install their electro magnet assembly. Without damaging the basket and soft parts, that's gotta be tricky! Plus they also supply the adjustable power supply so you can change the magnet strength. Not only that but they either make all those parts in house or have them made. So yeah, you buy a Celestion Blue or Gold with their set up and it's not gonna be cheap!
I think they've got a real good idea there! (wish I would've thought of it)
I am a little curious how they got a patent on what appears to be technologies that were common place until the early 1950s, field coil speaker magnets.
If one of the bigger companies got around the patent the economics of large scale production would cut costs. I'm thinking they just don't see a large enough market to bother with it.
 

HotBluePlates

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10,654
... I am a little curious how they got a patent on what appears to be technologies that were common place until the early 1950s, field coil speaker magnets. ...
As Fluxtone said in an interview, they're not patenting the field coil but a manner of use (to control/reduce "the output of a transducer" meaning speaker).

... If one of the bigger companies got around the patent the economics of large scale production would cut costs. I'm thinking they just don't see a large enough market to bother with it.
I'm sure Fluxtone wants to get paid a license fee for their Good Idea.

The big companies probably estimate that "Economy of Scale + License Fee = a Price Higher than Broke Musicians Will Pay."

I suppose we will find out in 5-8 years (when the patent protection expires) whether the big companies think Economy of Scale w/o License Fee will result in a price enough musicians will pay to recoup setup costs & turn a profit.
 




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