inefficient speaker hunt

TPR · 10-15-2009, 05:06 PM

Anyone have a preference for a particular inefficient speaker? I want to try something out to get earlier breakup and push the power tubes, preferably 12" 8 ohm. I'd be using 2 for a 50 watt jcm 900. Thanks.

nofearfactor · 10-15-2009, 05:37 PM

running them in series or parallel?

TPR · 10-15-2009, 07:41 PM

Series. I don't think the 4 ohm tap is connected on the 900. Well, hell, besides that I'm looking for as much inefficiency as I can get, so 16 ohm all the way for the speaker setup. I'll try the amp at 8 and 16 to see if there's much difference.

MartyStrat54 · 10-15-2009, 08:01 PM

That's a tough one, because most guitar speakers are rated at 97dB and up. There are very few at 97, most seem to be between 99 and 102dB. You might have to go with an accordion edge (textile/cloth edge) speaker with a heavy cone. Something like a mid PA speaker.

I have some old 4 by 12 cabs loaded with vintage speakers. They are all accordion edge and are probably around 95-96db. However, with four they are loud.

Keep in mind that if you find a 97dB speaker and you add another one, the rating goes up to 100dB.

I'll do some looking and if I find anything I'll post it.

TPR · 10-15-2009, 08:46 PM

Quote:

Originally Posted by MartyStrat54

That's a tough one, because most guitar speakers are rated at 97dB and up. There are very few at 97, most seem to be between 99 and 102dB. You might have to go with an accordion edge (textile/cloth edge) speaker with a heavy cone. Something like a mid PA speaker.

Thanks, Marty. Yeah, I'm starting to think this is going to be a pretty dry well. Most new speakers seem to be made to be more efficient, and the older, less efficient speakers like greenbacks are more than I can justify for this experiment.

How much of a factor does the impedance play? Let's say I get a couple of 16 ohm speakers wired in series. Would that have an audible effect? Also, would that be hard on the OT or the tubes?

TPR · 10-15-2009, 08:53 PM

Hey, check out what I just found. It's a technical explanation, so of course it must be right.

"Speakers are generally rated in Sound Pressure Level, or SPL. A "perfect" speaker that could convert 100% of the power applied to it int sound would have a SPL of 112dbP (the "P" is reference to Pascals).

Every 10dbP increment less than 112dbP is a effiency reduction of a factor of 10. Most research submits that a 10dbP increase, or decrease in SPL equates to about a halving or doubling of perceived volume.

So, a 102dbP SPL speaker would be 10% efficient at converting electrical energy to sound, 92dbP SPL is 1% efficient."
Speaker sensitivity question... - Telecaster Guitar Forum

Still reading through it.

MartyStrat54 · 10-15-2009, 08:58 PM

16 + 16 = 32 ohms. Not good for the output transformer. You would want to find two inefficient 8 ohm speakers and wire them in series for 16 ohm.

Here is an excerpt from my Speaker thread:

Each time the resistivity halves (i.e. goes from 8 ohm to 4 ohm, etc.), the sensitivity doubles, and quite vice versa. So, when connecting two 8-ohm speakers in parallel, the impedance drops to 4 ohm and the sensitivity increases 3dB because the amplifier develops more power into the lower impedance. If you would connect the two drivers in series, the impedance increases to 16 ohm. Ignoring for a moment the cone-area increase's effect, the sensitivity will drop 3dB because the amplifier produces less power into the higher impedance.
This is based on the following principle: when the impedance halves, the amplifier doubles it's output power, and hence the 3dB rise in output level. In a solid-state amp this works, but what about the valve amp. Their spec.sheet usually indicates the same power into 4, 8 or 16 ohms. So they do not add the 3dB increase.

Increase of sensitivity due to enlarged cone area

For each doubling of the cone area, the sensitivity rises 3dB, i.e. if you have one cone, adding a second one will add 3dB to the sensitivity (ignoring for the moment changes of impedance). Now with two cones, Sd must be doubled (total four cones) to add another 3dB to the sensitivity. To increase the sensitivity another 3dB, you need to add four cones, etc. ad infinitum.

TPR · 10-15-2009, 09:29 PM

"16 + 16 = 32 ohms. Not good for the output transformer."

Yup, I knew that series meant adding the imp of each speaker, so that's why I was wondering about affect on the OT. My understanding about impedance matching has always been that it's "best" to match, but safe to mismatch as long as the amp was pushing against a higher load. And that info is from Eminence, THD and others, not just some 14 year old's posts, so I figured it was safe. I just thought that when they say "best", it means they assume we're looking for the highest efficiency. But hey, maybe I'm the one making assumptions.

Thanks for reposting the speaker info. Was I correct in thinking that the higher impedance offset translates loosely into lower efficiency? Or does sensitivity mean something vastly different here than efficiency?

Well, I'm rambling a bit. The info is greatly appreciated. I'm still reading up as much as I can, so hopefully soon I'll have a better idea of what I'm talking about and not just pulling stuff out of my ass.

T-Bird · 10-15-2009, 11:23 PM

Hi.

Do remember when connecting speakers in series (or using only one for that matter) with a tube amp, that any problems will almost certainly create an open connection. That will fry the OT in a heartbeat if in full blast.

If You're just experimenting with inefficiency, you might want to look at some car audio speakers. I've had some good experiences with them (bad as well, obviously

).

Regards
Sam

JohnH · 10-16-2009, 12:35 AM

A great choice, that I have, is an old 8412 valvestate cab, which came with G12L-35 speakers - small magnet so probably 95db efficiency. Read this:

Marshall 8412 cabinet with Celestion G12L

With a valve amp, my understanding is that provide you match ohms from amp to cab, the Ohms value does not affect loudness for a given speaker and amp type.

John

TPR · 10-16-2009, 11:01 AM

Quote:

Originally Posted by T-Bird

Hi.

Do remember when connecting speakers in series (or using only one for that matter) with a tube amp, that any problems will almost certainly create an open connection. That will fry the OT in a heartbeat if in full blast.

Thanks, Sam. I'll make sure to check the connections from time to time. Do you have any other specific recommendations for keeping that from happening, like redundant wiring? I plan to remain in series to get 16 ohms out of my two 8 ohm speakers.

JohnH, thanks for the tip and the link. I'll keep an eye out for those speakers. There's only one on fleabay right now.

Mullard Man · 10-17-2009, 12:37 AM

I have a 4-12 with Celestion Silver Series V12-60's. They have a Greenback type of sound but seem to handle higher gain better. They are only rated at 96db.

The speaker was discontinued a few years back, but it might be worth trying to find some used ones, as they are under the radar for most people.

MartyStrat54 · 10-17-2009, 08:31 PM

Quote:

Originally Posted by JohnH

With a valve amp, my understanding is that provide you match ohms from amp to cab, the Ohms value does not affect loudness for a given speaker and amp type.

John

That is correct. The +3dB rule only applies to solid state amps.

Wilder Amplification · 10-17-2009, 09:58 PM

Quote:

Originally Posted by MartyStrat54

That is correct. The +3dB rule only applies to solid state amps.

X2. Valve amps put out the same power into each type of load provided the impedance is matched, which it always should be.

The main reason for having speakers with different impedance ratings is to be able to run more cabs and not so much a tonal thing. If you want to run more cabs, you have to have higher impedance speakers since the total load impedance drops the more cabs/speakers you add.

If you're looking for earlier breakup, I would suggest going with a lower wattage speaker rather than lower efficiency. Also keep in mind that brand new speakers will require "break-in" time before they sound their best as the cones will be stiff when they're brand new.

MartyStrat54 · 10-17-2009, 10:11 PM

Quote:

Originally Posted by Wilder Amplification

<Snip>If you're looking for earlier breakup, I would suggest going with a lower wattage speaker rather than lower efficiency. Also keep in mind that brand new speakers will require "break-in" time before they sound their best as the cones will be stiff when they're brand new.

While I agree that a low watt speaker will "break up" due to "X" amount of power going into it, I would have to warn about this practice. This is something that has been in practice since the dawn of rock. It takes experience to do this. Too much power for too long will end up with a fried speaker. They say that a 25 watt speaker taking 50 watts sounds its best right before it fries.

Wilder Amplification · 10-17-2009, 10:26 PM

Quote:

Originally Posted by MartyStrat54

While I agree that a low watt speaker will "break up" due to "X" amount of power going into it, I would have to warn about this practice. This is something that has been in practice since the dawn of rock. It takes experience to do this. Too much power for too long will end up with a fried speaker. They say that a 25 watt speaker taking 50 watts sounds its best right before it fries.

I'm not saying to get speakers that are rated for lower than what the amp is putting into them. Take my Super Lead for instance. I run it on a 120 watt cab with four 30 watt Celestions. I also run a Power Brake between the head and the cab itself. In this configuration is where I think it sounds its best.

Now put that same amp with the Power Brake and run it through a 1960A cab with G12T-75s and there's way too much low end there for me. But you still hear a difference...even though the power is limited to my lower rated speakers via the Power Brake, there's still a tone difference between the lower and higher wattage speakers due to the speakers being pushed closer to their power rating. You don't want to exceed the power rating of the speaker by any means, but you definitely get the best tone out of them by pushing them closer to their rating IMHO.

And yes, keep in mind that a 50 watt valve amp can put out WAY more than 50 watts when cranked and distorted.

10-15-2009, 05:06 PM	#1 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	inefficient speaker hunt Anyone have a preference for a particular inefficient speaker? I want to try something out to get earlier breakup and push the power tubes, preferably 12" 8 ohm. I'd be using 2 for a 50 watt jcm 900. Thanks. __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-15-2009, 05:37 PM	#2 (permalink)
nofearfactor Senior Member Join Date: Mar 2009 Location: Hellbillyville Posts: 178	Re: inefficient speaker hunt running them in series or parallel? __________________ myspace- http://www.myspace.com/nofearfactor some gear pics- http://community.webshots.com/album/...ecurity=QbSaeN

10-15-2009, 07:41 PM	#3 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	Re: inefficient speaker hunt Series. I don't think the 4 ohm tap is connected on the 900. Well, hell, besides that I'm looking for as much inefficiency as I can get, so 16 ohm all the way for the speaker setup. I'll try the amp at 8 and 16 to see if there's much difference. __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-15-2009, 08:01 PM	#4 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: inefficient speaker hunt That's a tough one, because most guitar speakers are rated at 97dB and up. There are very few at 97, most seem to be between 99 and 102dB. You might have to go with an accordion edge (textile/cloth edge) speaker with a heavy cone. Something like a mid PA speaker. I have some old 4 by 12 cabs loaded with vintage speakers. They are all accordion edge and are probably around 95-96db. However, with four they are loud. Keep in mind that if you find a 97dB speaker and you add another one, the rating goes up to 100dB. I'll do some looking and if I find anything I'll post it. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-15-2009, 08:53 PM	#6 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	Re: inefficient speaker hunt Hey, check out what I just found. It's a technical explanation, so of course it must be right. "Speakers are generally rated in Sound Pressure Level, or SPL. A "perfect" speaker that could convert 100% of the power applied to it int sound would have a SPL of 112dbP (the "P" is reference to Pascals). Every 10dbP increment less than 112dbP is a effiency reduction of a factor of 10. Most research submits that a 10dbP increase, or decrease in SPL equates to about a halving or doubling of perceived volume. So, a 102dbP SPL speaker would be 10% efficient at converting electrical energy to sound, 92dbP SPL is 1% efficient." Speaker sensitivity question... - Telecaster Guitar Forum Still reading through it. __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-15-2009, 08:58 PM	#7 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: inefficient speaker hunt 16 + 16 = 32 ohms. Not good for the output transformer. You would want to find two inefficient 8 ohm speakers and wire them in series for 16 ohm. Here is an excerpt from my Speaker thread: Each time the resistivity halves (i.e. goes from 8 ohm to 4 ohm, etc.), the sensitivity doubles, and quite vice versa. So, when connecting two 8-ohm speakers in parallel, the impedance drops to 4 ohm and the sensitivity increases 3dB because the amplifier develops more power into the lower impedance. If you would connect the two drivers in series, the impedance increases to 16 ohm. Ignoring for a moment the cone-area increase's effect, the sensitivity will drop 3dB because the amplifier produces less power into the higher impedance. This is based on the following principle: when the impedance halves, the amplifier doubles it's output power, and hence the 3dB rise in output level. In a solid-state amp this works, but what about the valve amp. Their spec.sheet usually indicates the same power into 4, 8 or 16 ohms. So they do not add the 3dB increase. Increase of sensitivity due to enlarged cone area For each doubling of the cone area, the sensitivity rises 3dB, i.e. if you have one cone, adding a second one will add 3dB to the sensitivity (ignoring for the moment changes of impedance). Now with two cones, Sd must be doubled (total four cones) to add another 3dB to the sensitivity. To increase the sensitivity another 3dB, you need to add four cones, etc. ad infinitum. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-15-2009, 09:29 PM	#8 (permalink)
TPR Senior Member Join Date: Sep 2009 Posts: 109	Re: inefficient speaker hunt "16 + 16 = 32 ohms. Not good for the output transformer." Yup, I knew that series meant adding the imp of each speaker, so that's why I was wondering about affect on the OT. My understanding about impedance matching has always been that it's "best" to match, but safe to mismatch as long as the amp was pushing against a higher load. And that info is from Eminence, THD and others, not just some 14 year old's posts, so I figured it was safe. I just thought that when they say "best", it means they assume we're looking for the highest efficiency. But hey, maybe I'm the one making assumptions. Thanks for reposting the speaker info. Was I correct in thinking that the higher impedance offset translates loosely into lower efficiency? Or does sensitivity mean something vastly different here than efficiency? Well, I'm rambling a bit. The info is greatly appreciated. I'm still reading up as much as I can, so hopefully soon I'll have a better idea of what I'm talking about and not just pulling stuff out of my ass. __________________ The awesome tone coming out of my amp almost makes up for my inability to play. '91 JCM 900 Head w/ EL34s '68 Bassman Head- Blackfaced Hand Built 2x12 Classic 30 Gibson LP Studio w/ PAFs Epi LP Standard w/ G 57s The usual assortment of pedals and stuff

10-15-2009, 11:23 PM	#9 (permalink)
T-Bird Senior Member Join Date: Jul 2009 Location: Finland (Northern Europe) Posts: 151	Re: inefficient speaker hunt Hi. Do remember when connecting speakers in series (or using only one for that matter) with a tube amp, that any problems will almost certainly create an open connection. That will fry the OT in a heartbeat if in full blast. If You're just experimenting with inefficiency, you might want to look at some car audio speakers. I've had some good experiences with them (bad as well, obviously ). Regards Sam

10-16-2009, 12:35 AM	#10 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 640	Re: inefficient speaker hunt A great choice, that I have, is an old 8412 valvestate cab, which came with G12L-35 speakers - small magnet so probably 95db efficiency. Read this: Marshall 8412 cabinet with Celestion G12L With a valve amp, my understanding is that provide you match ohms from amp to cab, the Ohms value does not affect loudness for a given speaker and amp type. John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

10-17-2009, 12:37 AM	#12 (permalink)
Mullard Man Member Join Date: Sep 2008 Posts: 63	Re: inefficient speaker hunt I have a 4-12 with Celestion Silver Series V12-60's. They have a Greenback type of sound but seem to handle higher gain better. They are only rated at 96db. The speaker was discontinued a few years back, but it might be worth trying to find some used ones, as they are under the radar for most people.

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