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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 3:43 am
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glennc717 wrote:
shimmilou wrote:
Overloaded means that if a 30 watt speaker is getting 50 watts of power, the speaker's max wattage rating will be exceeded, and that speaker can blow.

If using two speakers, that are each 8 ohms impedance on a 15 watt BJr, each speaker will get roughly 7.5 watts of power. Obviously, both speakers are rated to handle more than 7.5 watts each, so this is good.


Thanks shimmilou,
So for the scenario of the 15 Watt Blue Jr. there is no danger, is there a sound quality difference between the speakers as described, in your opinion? I mean hypothetically if you had a 30 Watt Greenback and a 50 Watt Greenback in the 212 for the Fender Blues Jr would there be any difference at all?? Theoretically with an underpowered amp is there no reason to match impedance's? Cheers Glenn



50w & 30w speakers are built differently.
The amp would push each speaker differently.
If you installed:
two 30w Greenbacks, or
two 50w Greenbacks, or
both a 30w and 50w speakers . . . . .

All three will definitely will sound different.
Have fun, Glenn. Toppscore 8)

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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:07 am
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glennc717 wrote:
is there a sound quality difference between the speakers as described, in your opinion? I mean hypothetically if you had a 30 Watt Greenback and a 50 Watt Greenback in the 212 for the Fender Blues Jr would there be any difference at all??


As I understand it, there are slight tonal differences when you change the wattage rating.

Because you are comparing two different speaker makes and models (Eminence and Celestion right?), they're going to sound different even if they had the same wattage rating. Search on Google and I'm sure you'll find threads by people who've paired a Greenback and a Cannabis Rex so you can judge if it's a good match for you. They're both very popular rock speakers, but I don't know whether they complement eachother well.

There is no way to simply increase the wattage of a speaker without a change in tone. You'd have to make structural changes to increase the wattage and so the whole thing responds differently because it's built differently. So two speakers of the same make and model with different wattage ratings do have a difference in tone. Here's an awesome article that decribes it in depth: http://celestion.com/speakerworld/guita ... _Speakers/

Lower wattage will break up sooner and higher wattage will have more clean headroom. If you are using the 50w and 30w together with a 15w amp you may not get very much speaker breakup at all because neither speaker is really being pushed hard.

As I remember, lower wattage is 'warmer' and more 'colored,' while higher wattage is less so, more of a direct reproduction of your input signal. But don't quote me on that!


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:22 am
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Toppscore wrote:
glennc717 wrote:
shimmilou wrote:
Overloaded means that if a 30 watt speaker is getting 50 watts of power, the speaker's max wattage rating will be exceeded, and that speaker can blow.

If using two speakers, that are each 8 ohms impedance on a 15 watt BJr, each speaker will get roughly 7.5 watts of power. Obviously, both speakers are rated to handle more than 7.5 watts each, so this is good.


Thanks shimmilou,
So for the scenario of the 15 Watt Blue Jr. there is no danger, is there a sound quality difference between the speakers as described, in your opinion? I mean hypothetically if you had a 30 Watt Greenback and a 50 Watt Greenback in the 212 for the Fender Blues Jr would there be any difference at all?? Theoretically with an underpowered amp is there no reason to match impedance's? Cheers Glenn



50w & 30w speakers are built differently.
The amp would push each speaker differently.
If you installed:
two 30w Greenbacks, or
two 50w Greenbacks, or
both a 30w and 50w speakers . . . . .

All three will definitely will sound different.
Have fun, Glenn. Toppscore 8)


Thanks Toppscore!!


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:24 am
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demaria.daniel wrote:
glennc717 wrote:
is there a sound quality difference between the speakers as described, in your opinion? I mean hypothetically if you had a 30 Watt Greenback and a 50 Watt Greenback in the 212 for the Fender Blues Jr would there be any difference at all??


As I understand it, there are slight tonal differences when you change the wattage rating.

Because you are comparing two different speaker makes and models (Eminence and Celestion right?), they're going to sound different even if they had the same wattage rating. Search on Google and I'm sure you'll find threads by people who've paired a Greenback and a Cannabis Rex so you can judge if it's a good match for you. They're both very popular rock speakers, but I don't know whether they complement eachother well.

There is no way to simply increase the wattage of a speaker without a change in tone. You'd have to make structural changes to increase the wattage and so the whole thing responds differently because it's built differently. So two speakers of the same make and model with different wattage ratings do have a difference in tone. Here's an awesome article that decribes it in depth: http://celestion.com/speakerworld/guita ... _Speakers/

Lower wattage will break up sooner and higher wattage will have more clean headroom. If you are using the 50w and 30w together with a 15w amp you may not get very much speaker breakup at all because neither speaker is really being pushed hard.

As I remember, lower wattage is 'warmer' and more 'colored,' while higher wattage is less so, more of a direct reproduction of your input signal. But don't quote me on that!


Hello and thanks for the great response. This is what I had glimpsed in my travels, and I will certainly look at that link! Glad you stopped by!
Glenn


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:24 am
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glennc717 wrote:
What would be the negative consequences of say running a 50 Watt speaker in series or parallel with say a 25 Watt speaker?


The other thing you want to be mindful of are the Speaker Sensitivty ratings.

This is an indication (in overly simple terms) of how loud the speaker is.

It takes 3dB to notice a difference in volume. So, if the sensitivty ratings are within 2dB of eachother, they should be about the same volume. You don't want one speaker to overpower the other. Eminence and Celestion both publish sensitivty ratings on their websites so you can compare easily.


I play a 1967 Bassman with a 50w Weber 10f150-T speaker and a 30w Weber 10a125 speaker. The 50w is definitely brighter and the the 30w has much more bass response. The two together make a real full, layered sound and are definitely different but complementary. They are the same impedance and there's no problems running them as a pair despite the different wattages. (except that given my amp is rated at 50watts, I probably should have bought a 50w alnico to be on the safe side)


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:34 am
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Toppscore wrote:
shimmilou wrote:
When using multiple speakers (each is same impedance), the power from the amp will divide roughly evenly between the speakers. Two speakers, each gets half of the power from the amp. Three speakers, each gets a third of the amp power. Etc.

If you use two speakers with a 100 watt amp, one 30 watt speaker and one 50 watt speaker, each speaker will get roughly 50 watts at the amp's full power. As you can guess, the 30 watt speaker can be overloaded in this scenario.



Question of least resistance:
If a 100w amp sees a 30w speaker and a 50w speaker in a 2x12 setup
or
If a 4-ohm amp sees an 8-ohm speaker and a 16-ohm speaker in a 2x12 setup

Would not the weaker speaker get more load and the stronger speaker resist
more than the weaker speaker forcing more load towards the weaker speaker?


Toppscore :
[/color]

This gets much more complicated , the amp would see 5.333333333333333 Ohms.

Try this link http://www.diyaudioandvideo.com/FAQ/Wiring/ and look for
"How do you run speakers in parallel?"

This is actually very simplified but suffice to say that impedance is not just a matter of adding and subtracting simple numbers, especially once you involve things like inductance. Also be aware that there are other factors that can change the impedance. Just look at the specs for the greenback....

http://celestion.com/product/16/g12m_greenback/

This is why you always see speakers of like impedance in cabinets, or complex wiring to insure that the amp will see the correct impedance.

While 5.33333333333 will not hurt an amp expecting a 4 ohm load, it still is not 4 ohm. In this situation, it won't hurt anything, but there are other applications where impedance matching must be spot on.

Briefly:
A measure of the total opposition to current flow in an alternating current circuit, made up of two components, ohmic resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance.

In direct current, capacitance and induction also play a part.

Art


Last edited by Art1 on Thu Sep 06, 2012 9:41 am, edited 1 time in total.

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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 9:36 am
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To me, everything has different sounds & tones.
Too many imperfections and options.
Cabinet wood, age, cold weather,
constant usage, minimal usage.
1959 Jensen 30w (vs) 2006 Celestion 30w
Reconed or cracked coned or factory NOS new.

Life is good.
Just keep the ohms lined up right.
Just keep the wattage in close range.

Take care. Toppscore :)

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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 10:21 am
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demaria.daniel wrote:
glennc717 wrote:
What would be the negative consequences of say running a 50 Watt speaker in series or parallel with say a 25 Watt speaker?


The other thing you want to be mindful of are the Speaker Sensitivty ratings.

This is an indication (in overly simple terms) of how loud the speaker is.

It takes 3dB to notice a difference in volume. So, if the sensitivty ratings are within 2dB of eachother, they should be about the same volume. You don't want one speaker to overpower the other. Eminence and Celestion both publish sensitivty ratings on their websites so you can compare easily.


I play a 1967 Bassman with a 50w Weber 10f150-T speaker and a 30w Weber 10a125 speaker. The 50w is definitely brighter and the the 30w has much more bass response. The two together make a real full, layered sound and are definitely different but complementary. They are the same impedance and there's no problems running them as a pair despite the different wattages. (except that given my amp is rated at 50watts, I probably should have bought a 50w alnico to be on the safe side)


Hello demaria.daniel,
Oh shoot. I better buckle up, this is going to be a bumpy ride... Okay, I believe I know what the sensitivity rating is so I will go find out. Mille Grazie = a bunch of thanks
Glenn

GB = 95 dB
CR = 102 dB
Big difference = yes!?!!!


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 10:37 am
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Art1 wrote:
Toppscore wrote:
shimmilou wrote:
When using multiple speakers (each is same impedance), the power from the amp will divide roughly evenly between the speakers. Two speakers, each gets half of the power from the amp. Three speakers, each gets a third of the amp power. Etc.

If you use two speakers with a 100 watt amp, one 30 watt speaker and one 50 watt speaker, each speaker will get roughly 50 watts at the amp's full power. As you can guess, the 30 watt speaker can be overloaded in this scenario.



Question of least resistance:
If a 100w amp sees a 30w speaker and a 50w speaker in a 2x12 setup
or
If a 4-ohm amp sees an 8-ohm speaker and a 16-ohm speaker in a 2x12 setup

Would not the weaker speaker get more load and the stronger speaker resist
more than the weaker speaker forcing more load towards the weaker speaker?


Toppscore :
[/color]

This gets much more complicated , the amp would see 5.333333333333333 Ohms.

Try this link http://www.diyaudioandvideo.com/FAQ/Wiring/ and look for
"How do you run speakers in parallel?"

This is actually very simplified but suffice to say that impedance is not just a matter of adding and subtracting simple numbers, especially once you involve things like inductance. Also be aware that there are other factors that can change the impedance. Just look at the specs for the greenback....

http://celestion.com/product/16/g12m_greenback/

This is why you always see speakers of like impedance in cabinets, or complex wiring to insure that the amp will see the correct impedance.

While 5.33333333333 will not hurt an amp expecting a 4 ohm load, it still is not 4 ohm. In this situation, it won't hurt anything, but there are other applications where impedance matching must be spot on.

Briefly:
A measure of the total opposition to current flow in an alternating current circuit, made up of two components, ohmic resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance.

In direct current, capacitance and induction also play a part.

Art


I had a feeling Art, that it wouldn't be long before that reactance stuff would be brought up. 25 years ago I could have calculated it as well as RMS. Those synapsis are long dormant.. Thanks for the great and detailed information!
Glenn


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 10:41 am
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Prego!
Huge difference.
Try wgs4.com
Warehouse Speakers build 'replacements' for Celestions that many people actually prefer to current production Celestions.
The 'Green Beret' and 'Invader 50' in the British Invasion line are their variations on the Greenback.
Most Warehouse speakers have a sensitivity in the 100dB range. You can find the Sensitivty ratings on the 'Tone Chart' link on the left hand side of the page.


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 10:48 am
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Glenn,

I had to look it up as well. I went through ET school 40 years ago. You can imagine just how deep that stuff is buried under countless brewski's. :lol:

You want to get confused? Look at that greenback's DC resistance then look at the "Nominal" impedance. Then remember that there is inductance involved (it is after all a coil and a magnet.)


Art


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 5:12 pm
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demaria.daniel wrote:
Prego!
Huge difference.
Try wgs4.com
Warehouse Speakers build 'replacements' for Celestions that many people actually prefer to current production Celestions.
The 'Green Beret' and 'Invader 50' in the British Invasion line are their variations on the Greenback.
Most Warehouse speakers have a sensitivity in the 100dB range. You can find the Sensitivty ratings on the 'Tone Chart' link on the left hand side of the page.


Hey there demaria.daniel,
Thanks for the site, maybe be able to get what I need. Grazie Signore!
Glenn


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 5:15 pm
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Art1 wrote:
Glenn,

I had to look it up as well. I went through ET school 40 years ago. You can imagine just how deep that stuff is buried under countless brewski's. :lol:

You want to get confused? Look at that greenback's DC resistance then look at the "Nominal" impedance. Then remember that there is inductance involved (it is after all a coil and a magnet.)


Art


It used to be so easy, now it might as well be Incan. Yeah quite a while and life between then and now. Thanks for the memories and you great assistance!
Grazie
Glenn


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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Thu Sep 06, 2012 11:01 pm
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Thanks Art & Glenn.
I am getting fried with all the EE chat.
I like to "see the ball" "hit the ball"
rather than understanding the rotation, air humidity,
bat weight, etc. I better understand Parallel, as I should.
As well, I better understand watts & ohms as they relate
to speaker/amplifier handshaking.

But, I do not understand that the amp will see 5.3333 ohms
when a 16-ohm weaker speaker and an 8-ohm stronger speaker
will not allow the amp's energy flow to the weakest point
rather than pushing both speakers at 5.3333-ohms.
That is what EE school is for. :lol: :lol: :lol:


Toppscore 8)

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Post subject: Re: 212 Cabinet for the Fender Blues Junior
Posted: Fri Sep 07, 2012 7:58 am
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Toppscore wrote:
...But, I do not understand that the amp will see 5.3333 ohms
when a 16-ohm weaker speaker and an 8-ohm stronger speaker
will not allow the amp's energy flow to the weakest point
rather than pushing both speakers at 5.3333-ohms...


The amp sees a total of 5.3 ohms, it can't tell how many speakers are connected, it sees only one load. But, the current from the amp will still divide between the speakers, more current going to the 8 ohm speaker and less going to the 16 ohm speaker.

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