Speaker Watts - Jemsite
Gear, Equipment, Recording & Off Topic Gear, Equipment, and Recording discussed here. Amps, pedals, whatever.

 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 11-10-2009, 09:57 AM Thread Starter
 
Join Date: May 2008
Location: Philippines
Posts: 197
Reviews: 23
Question Speaker Watts

Hello people, so after getting the LC50 a few months ago (sorry I couldn't make clips yet) I've been dreaming about getting a 2x12 extension cabinet built (I got plans from the internet) for it, not only because it would probably be louder but also because it'll help with preventing tube microphonics due to sound waves pounding on the tubes from the back of the stock speaker's cone. Plus it'll probably help with tightening the low end a bit.

Here's the first problem: the LC50 has 50 watts of power, and I know that there are things like impedance and wattage that need to be considered when buying new speakers to match them to the amp. I plan to wire two 12 inch Jensen MODs in parallel, and each speaker should be rated at 16 ohms so that when connected to the amp they would only have 8 ohms (the amp's rated impedance), right? How about the wattage of the speakers then? For instance, would two 110 watt speakers add up to 220 watts when connected in parallel or would they stay at 110 watts?

According to the Jensen website, speaker watts should be at least double the amp's for longer speaker life. I assume that this has to do with the RMS/Peak wattage rating thing on amps? The one that says 30 watt amps MAY go a bit over 30 watts when 'pushed harder', for example? Should I use speakers with 100 watts total to satisfy this condition, or would 50 watts do fine?

Second problem: while I do love my LC50, I still keep my crappy MG100DFX for when I'm just messing around with effects and practicing, and so it would be great if I could also hook up the 2x12 cab to it if need be. However, it is rated at 100 watts. Again, according to the Jensen website, speaker watts should at least be double the amp's wattage for longer speaker life. If this were true, then I should get speakers with watts adding up to 200. However, going back to the LC50, how would speakers 4 times the amp's wattage affect the tone?

Thanks in advance for reading the post, I hope you could give some advice. BTW, I'm trying to save on costs so I just might the relatively cheap MODs, which seem to be favored quite well by people.
theapprentice is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 11-10-2009, 10:45 AM
 
Join Date: Jan 2007
Location: South West UK
Posts: 953
Re: Speaker Watts

1) However you connect a pair of speakers up, the power is shared, so 2 50W speakers will handle 100W whether in series or parallel (in series they each get half the voltage, in parallel they get half the current)
2) You should definitely over specify your cab for the amp's power, especially a valve amp, having speakers that can handle 2 times the amps output is not unreasonable, a typical Marshall 4x12 handles about 300W for example!
3) You'd be hard pressed to make a 2x12 that can handle 200W, again Marshall's 2x12s handle 150W, although I don't have the specs of the speakers in their 100W 2x12 combo...

Generally higher rated speakers run at less power (e.g. 50W amp into 300W 4x12) sounds fine, but you are paying for power handling you're not using. But some people say running speakers nearer their limit sounds better...
Jim
Vim Fuego is offline  
post #3 of 11 (permalink) Old 11-11-2009, 09:33 AM
 
Join Date: Mar 2002
Location: Prato, Italy
Posts: 107
Re: Speaker Watts

And of course if you have a Ferrari you always go to 200MPH, it's better to understand how much power/Watts is going to the speakers first, even the most popular amps have a way exagerated declared power.
Example: Mesa Road King the manufacturer declared max power is 120, in reality depending on which brand of tubes and bias you get, if you are lucky, around 80, of this 80 how many do you think are going to be used by the average guitarist?
No more than 30, divided by two cones is a mere 15 each, you could put alnico blues and still have plenty to spare for regular use.
Stefano
maialinodivino is offline  
post #4 of 11 (permalink) Old 11-11-2009, 09:49 AM
 
Join Date: Jan 2007
Location: South West UK
Posts: 953
Re: Speaker Watts

^
True,
But, the energy stored in the capacitors of the power supply of a valve amp allows the instantaneous power to far exceed the quoted RMS figures, even if the amp is usually used at comparatively low volumes.
Better to be safe rather than sorry, is, I think, the general rule the manufacturers recommend.
Jim
Vim Fuego is offline  
post #5 of 11 (permalink) Old 11-11-2009, 10:10 AM Thread Starter
 
Join Date: May 2008
Location: Philippines
Posts: 197
Reviews: 23
Re: Speaker Watts

Jim, I kinda wanted to find a happy balance between using such a cab setup on both the LC50 and the MG100DFX, so what do you think should I get? the Jensen MOD 12" speakers have 35, 50, 70, and 110 watt versions. To avoid phase problems I'd probably get two of the same kind, and I was rooting for either the 70 or 110 watt versions (I was considering the 110 watter because they seem to have tighter voicing and greater speaker efficiency). I am also one of the people who think that speakers sound best when pushed a bit, but it would really be nice if I could do so safely on both amps. Any suggestions?
theapprentice is offline  
post #6 of 11 (permalink) Old 11-11-2009, 10:18 AM
 
Join Date: Jan 2007
Location: South West UK
Posts: 953
Re: Speaker Watts

The MG is a transistor/solid state amp isn't it?
If so then you could go for the 70W speakers, as the 140W power handling will be plenty for the Laney and the MG is unlikely to produce more power than the quoted RMS of 100W.
It all comes down to cost/taste I'm afraid.
Jim
Vim Fuego is offline  
post #7 of 11 (permalink) Old 11-11-2009, 01:37 PM
 
Join Date: Feb 2007
Location: Southern California
Posts: 1,081
Reviews: 130
Re: Speaker Watts

You'll have one more unfortunate decision to make with respect to this setup, and that's with respect to the impedance of the cabinet. Characteristically, tube amps like to see and work better with higher resistance (so you can crank up the tubes and drive harder) but solid-state amps like to see lower resistance so that their full dynamics make it through the signal chain. Example: Most Marshall 4x12's are 16 Ohm, where a Crate 4x12 that comes with a solid state head is 4 Ohm. That difference is also seen between the Marshall 2x12 1936 (16 Ohm) and the Marshall MC212 (4 Ohm), because the 1936 is made to pair with tube heads, where the MC212 is made for the solid state heads. Doesn't mean you can't mix them, just means it's not "optimal." If you have the wiring chops, I'd wire so you can add an impedance select switch so you can go 16 Ohm for the LC50 and 4 ohm for the MG.

Cheers,

Bob
racerevlon is offline  
post #8 of 11 (permalink) Old 11-11-2009, 09:16 PM Thread Starter
 
Join Date: May 2008
Location: Philippines
Posts: 197
Reviews: 23
Question Re: Speaker Watts

^
I can do such a wiring scheme, I was able to find instructions over the net for that. Correct me if I'm wrong, Bob, but 16ohms impedance going into the LC50 which normally handles 8 ohms would make the volume slightly lower than when matched correctly, right? The MG does require at least 4 ohms speaker impedance to work safely.

I'm basically concerned with volume and compatibility of the proposed cab to both speakers. Jim said that the MG, being solid state, would hardly go beyond its 100 watt RMS rating, while the LC50 would be happy enough with 140 watts.

I have been thinking about this other plan that maybe I could just replace the MG's stock speaker to a Jensen MOD 110, and then build a cab with 2 50 watt MODs exclusively for the LC50, just to be sure. I was only worried that having a relatively ok speaker in a relatively mediocre amp would defeat the purpose. What do you guys suggest I do then?
theapprentice is offline  
post #9 of 11 (permalink) Old 11-12-2009, 11:42 AM
 
Join Date: Dec 2003
Location: Blackpool (England)
Posts: 266
Re: Speaker Watts

Quote:
Originally Posted by Vim Fuego View Post
^
True,
But, the energy stored in the capacitors of the power supply of a valve amp allows the instantaneous power to far exceed the quoted RMS figures, even if the amp is usually used at comparatively low volumes.
Better to be safe rather than sorry, is, I think, the general rule the manufacturers recommend.
Jim
This is interesting to me for a couple of reasons,

I have a 5153 head, I noticed the matching 4x12 is loaded with 20watt EVH speakers therby making the cab 80 watts, I contacted the manufacturer and they told me that the speakers, whilst listed as 20watts, in reallity could handle a lot more than that. Still strikes me as a bit odd.

I am running the EVH into a 2x12 with a G12M and a G12-65, when I bought the speakers I made the mistage of adding the wattage of the speakers together rather than multiplying the number of speakers by the lowest rating. So at the moment I effectively have a 50watt cab for a 100 watt head. I realised I am going to have to change out the greenback which sucks because those speakers sound awesome together. I was going to go with another G12-65 making the cab 130 watts, I am pretty shure this will be ok as I have never had the amp past 1/2.
Dazza1004 is offline  
post #10 of 11 (permalink) Old 11-13-2009, 05:20 AM
 
Join Date: Jan 2007
Location: South West UK
Posts: 953
Re: Speaker Watts

Yep, you might think this was pretty simple stuff, but everyone seems to have a different rule of thumb....
Just looked at the Celestion site, they recommend the speaker power should at least equal the power of the amp (rather than be double it like some amp manufacturers recommend). They *may* know what they're talking about!
One of the problems is people want the sound of the old low power speakers, but with better power handling which means you get things like the re-issue Vintage 30 being rated at 60W!
I noted the EVH are rated at 20 as you said, but I suspect they can handle more...
Plus as was said, unless you're at a pretty large gig, who tuns a 100W amp up fully!
You're right what you say about having a 50W cab though (lowest rated speaker = 25W so 2x12 cab can handle twice that). I guess you'll just have to take it easy (and make up another identical 2x12 for use at gigs!)
Jim
Vim Fuego is offline  
post #11 of 11 (permalink) Old 08-04-2010, 11:52 AM Thread Starter
 
Join Date: May 2008
Location: Philippines
Posts: 197
Reviews: 23
Smile Re: Speaker Watts

Hey guys, this thread's a little old, but I recently found out something about solid state amplifiers which may actually make my initial plan of building a 2x12, 8 ohm cab work!

According to wikipedia, SS amps don't really match impedance with its speakers (It states that typically SS designs have <0.1 ohms amp load), so that may mean that my MG100DFX doesn't really require 4 ohm speaker impedance to work well. The article states that solid state designs use "impedance bridging" to minimize the harsh overloading characteristics of SS amps by using speakers with way higher impedances with SS amps with such low impedances.

The article on loudspeakers can be found here: http://en.wikipedia.org/wiki/Impedan...rical_examples

Is there anything you can add to this piece of info I found that may help?

I don't think I'll go with the cab-building anymore, though. I'll simply buy those Jensen MODs I've wanted to try out for quite a while and put them into my amps. Building cabinets seem to be really tedious, and I'm not really good at woodworking. Thanks to those who replied
theapprentice is offline  
Reply

Tags
jensen mod , speaker

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Jemsite forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address

IMPORTANT: You will be required to activate your account so please ensure that your email address is correct.

If you do not receive your activation check your spam folder before using the CONTACT US form (at the bottom right of each page).



Email Address:
OR

Log-in











Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
WATTS TREVA Gear, Equipment, Recording & Off Topic 4 09-14-2007 10:25 AM
WTB: A tube amp 60 watts or less Queens_Brian_May Classified Ads: Guitars and Gear 4 06-17-2007 10:25 AM
Marshall JCM900 (50 watts) chi Gear, Equipment, Recording & Off Topic 1 04-22-2007 08:08 PM
Watts, Ohms... what? Jupiter Gear, Equipment, Recording & Off Topic 3 10-18-2003 06:21 AM
AMP POWER - significance of watts mmr7 Tech: Setup, Repairs and Mods 15 08-25-2001 07:49 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome