Need to add volume

[rpjazzguitar]

I'm wondering if anyone might have a thought about the following.

I'm happy with the sound of my Little Jazz, but I play in some settings where it's not quite loud enough.

Weight is almost as important as sound quality. The LJ is very comfortable at 15 lbs. Maybe 20 would be ok, but 25 is too much. I can make two trips.

One thing I'm wondering about is to get a small powered speaker (got the idea from Reg). I could run it from the XLR out on the LJ or I could mic the LJ. Then, I could run the LJ at a moderate volume setting and use the powered speaker for the rest.

Since I'm happy with the 8" speaker in the LJ, is there any reason to think about going to a larger one in the powered speaker?

Would a passive speaker cab run from the LJ actually increase volume by much?

Alto has a range of sizes.

What about a second LJ? That would double the amount of air being moved I guess, but what happens to perceived loudness?

And, out of left field, should I consider a line-array for any reason?

Any thoughts? Thanks in advance.

[Bobby Timmons]

You could just get a 2nd cabinet. I see the LJ has a speaker out port. I assume it would be an auxiliary out and keep the internal speaker on too but I'm not sure.

[6v6ster]

If you add another cab with a speaker of the same efficiency, you’ll get a 3db increase in volume. It’s there and is a decent bump but if you’re needing a LOT more volume then you might need a different option.

[coyote-1]

While you may be happy with the 8” speaker sound, IMO a 12” sounds much better. Much fuller.

That might be achievable with a powered cabinet, run from the LJ’s XLR out. I think that is an option worth seeking out. Might be able to score something used.

[marcwhy]

I like the second cab idea. How about an "always on" clean boost, too?

[rpjazzguitar]

I like the second cab idea. How about an "always on" clean boost, too?

I always play with a Boss ME80. I'm maxed out on the output level. I can add more volume by going to amp sims but they aren't all that clean.

[rpjazzguitar]

While you may be happy with the 8” speaker sound, IMO a 12” sounds much better. Much fuller.

That might be achievable with a powered cabinet, run from the LJ’s XLR out. I think that is an option worth seeking out. Might be able to score something used.

It might be hearing deficits, the nature of my guitar or just taste, but I'm already rolling the bass all the way off, or close. Not for solo guitar, but for my usual playing situations which almost always include bass and drums and, usually, a kb.

I have run the LJ into a PA (Yamaha Stagepas 300, among others) and it sounded good to me. That might not be a bad option, since I could take one speaker/mixer to the gig. And, have a PA if I ever need one.

[kris]

A long time ago I experimented with little guitar combos.
It is always the case that such amplifiers are very convenient to transport, but the volume is not always appropriate.
Small speakers have limitations and do not play cleanly at too high volume.
Therefore, such small amplifiers do not always work.
At home it's ok but in larger rooms it's a problem.
I tried with various additional cabinets and was not satisfied.
Perhaps an active cabinet would be a good solution, but again comes the extra weight.

[entresz]

I've run my LJ through an old JBL D-130 and it has heaps of volume - more than I'd ever need. I would think an extension cab with an efficient speaker would solve the issue.

[coyote-1]

It might be hearing deficits, the nature of my guitar or just taste, but I'm already rolling the bass all the way off, or close.

Small speakers have limitations and do not play cleanly at too high volume.

This. Rock/pop is one thing. Jazz is quite another. It’s not about “the bass”. It’s about headroom. The amp needs sufficient power, and the speaker sufficient magnet/coil/surface, to get to your volume without noticeable distortion. Especially since you’re typically feeding it a guitar signal that is at less than full output (again, to minimize distortion).

[nevershouldhavesoldit]

If you add another cab with a speaker of the same efficiency, you’ll get a 3db increase in volume. It’s there and is a decent bump but if you’re needing a LOT more volume then you might need a different option.

That's true in theory if the acoustic output in dB of each speaker in the pair is the same as the SPL generated by the internal speaker when no external cab is attached. But it's not exactly the case. The reduced impedance of the combined output bumps the amplifier's power output from 45 watts to 60, which is a 33% increase. But two identical speakers will lose twice as much power to heat, mechanical drag, coil resistance, electromagnetic radiation etc as one, and speakers are highly inefficient (which is expessed as acoustic watts out / electrical power in).

So a lot of the increased output power in watts will be lost to the added inefficiencies of the second speaker. If the amp's power supply can push a steady 65 watts through both speakers with normal program material, they'll both reach almost the same output level as one alone. Since SPL is a logarithmic measure, and our speakers are only about 0.1 to 0.5% efficient, even these small losses will reduce the gain in SPL by a dB or more over that theoretical 3.

Because of the above, substituting a 4 Ohm speaker with identical physical and operating parameters for the 8 Ohm internal driver in the amplifier will incease SPL a bit more than adding an external 8 Ohm speaker in parallel and will come closer to that full 3 dB gain. Using 2 speakers with physical separation provides two sources of acoustic radiation, which broadens the area over which the same SPL is received. And using multiple drivers in the same enclosure increases the output power and bumps the low end a bit. If all speakers are single cone, using multiple drivers can muddy the highs a bit because of phase incoherence at higher frequencies But the radiation pattern is about the same. So you'll sound slightly louder to you at the same location from the cabinet, but you won't be louder to most of the room.

And we're talking about SPL differences of somewhere between 1 and 2 dB in the real world, which is barely audible at best.

[Lionelsax]

Maybe they play too loud.

[kris]

Maybe they play too loud.

...or the guitarist wants to play louder.It's not that easy.

[Lionelsax]

Maybe a problem of EQ, do you feel you're not loud enough when you're comping or when you're soloing ?
Who said it wasn't loud enough ? The audience, the band or yourself ?

[rpjazzguitar]

Maybe a problem of EQ, do you feel you're not loud enough when you're comping or when you're soloing ?
Who said it wasn't loud enough ? The audience, the band or yourself ?

My impression and some band comments in one situation. Although, the problem with the band (19 piece) is that the people sitting close to me probably wouldn't want it any louder while the people sitting far away said they couldn't hear it. That's one reason I was thinking about line array.

A live recording of a gig in another situation. I had the amp as loud as I want to push it. Worked for the sound check, but not the recording.

It's more with getting comping to sound good.

[rpjazzguitar]

That's true in theory if the acoustic output in dB of each speaker in the pair is the same as the SPL generated by the internal speaker when no external cab is attached. But it's not exactly the case. The reduced impedance of the combined output bumps the amplifier's power output from 45 watts to 60, which is a 33% increase. But two identical speakers will lose twice as much power to heat, mechanical drag, coil resistance, electromagnetic radiation etc as one, and speakers are highly inefficient (which is expessed as acoustic watts out / electrical power in).

So a lot of the increased output power in watts will be lost to the added inefficiencies of the second speaker. If the amp's power supply can push a steady 65 watts through both speakers with normal program material, they'll both reach almost the same output level as one alone. Since SPL is a logarithmic measure, and our speakers are only about 0.1 to 0.5% efficient, even these small losses will reduce the gain in SPL by a dB or more over that theoretical 3.

Because of the above, substituting a 4 Ohm speaker with identical physical and operating parameters for the 8 Ohm internal driver in the amplifier will incease SPL a bit more than adding an external 8 Ohm speaker in parallel and will come closer to that full 3 dB gain. Using 2 speakers with physical separation provides two sources of acoustic radiation, which broadens the area over which the same SPL is received. And using multiple drivers in the same enclosure increases the output power and bumps the low end a bit. If all speakers are single cone, using multiple drivers can muddy the highs a bit because of phase incoherence at higher frequencies But the radiation pattern is about the same. So you'll sound slightly louder to you at the same location from the cabinet, but you won't be louder to most of the room.

And we're talking about SPL differences of somewhere between 1 and 2 dB in the real world, which is barely audible at best.

Thanks for this explanation. A bit over my head, but if I may I ask a simplistic question ...

If I plug an 8 ohm speaker into the LJ and leave the internal speaker on ... then the amplifier sees a 4 ohm load and pushes more watts.
Unless, the internal speaker isn't 8 ohms to being with, I guess. And they're connected in parallel, not series.

But, I get stuck with the notion that dividing the amp's power among two speakers doesn't somehow reduce (halve?) the power to each. That both speakers could be at the original SPL of the internal speaker sounds like magic. What am I missing?

And, then, if reducing the speaker impedence is effective (louder and still sounds good) why didn't the manufacturer do that with the internal speaker?

One other thing. What happens if I run two identical LJ's simultaneously? My pedalboard, an ME80, has left and right outputs (they imply stereo, but they're identical). Do I get more volume from two amps than amp + external speaker cab?

[rpjazzguitar]

This. Rock/pop is one thing. Jazz is quite another. It’s not about “the bass”. It’s about headroom. The amp needs sufficient power, and the speaker sufficient magnet/coil/surface, to get to your volume without noticeable distortion. Especially since you’re typically feeding it a guitar signal that is at less than full output (again, to minimize distortion).

I hadn't thought about that. I have tried the LJ with an external 12 inch speaker and I didn't think it improved the sound. But you're right, it was louder. I had assumed that was more about efficiency than size. Obviously, a different external cabinet might be better, or perhaps not.

"Sufficient magnet" sounds like more weight, which is an issue.

[Lionelsax]

My impression and some band comments in one situation. Although, the problem with the band (19 piece) is that the people sitting close to me probably wouldn't want it any louder while the people sitting far away said they couldn't hear it. That's one reason I was thinking about line array.

A live recording of a gig in another situation. I had the amp as loud as I want to push it. Worked for the sound check, but not the recording.

It's more with getting comping to sound good.

It's not your fault, your amp is too directional, have you ever tried to turn your amp against a wall or a corner ?
One day I tried and I heard my sound everywhere.
Tommy Emmanuel does that but he doesn't play with a big band.
When I say everywhere it's everywhere and kind of anywhere, same effect than when you play the saxophone against a wall or a corner.

Your band needs a PA system.

[coyote-1]

It's not your fault, your amp is too directional, have you ever tried to turn your amp against a wall or a corner ?
One day I tried and I heard my sound everywhere.
Tommy Emmanuel does that but he doesn't play with a big band.
When I say everywhere it's everywhere and kind of anywhere, same effect than when you play the saxophone against a wall or a corner.

Your band needs a PA system.

i actually use this concept for home audio. I have a “center channel” (from a 7.1 setup) in a bathroom. It sits on the tile floor underneath the vanity. Anyone using the room says the audio sounds like it’s coming from the ceiling fan, which is over the shower! It does not matter where you are in the room, it sounds like that.

[rpjazzguitar]

It's not your fault, your amp is too directional, have you ever tried to turn your amp against a wall or a corner ?
One day I tried and I heard my sound everywhere.
Tommy Emmanuel does that but he doesn't play with a big band.
When I say everywhere it's everywhere and kind of anywhere, same effect than when you play the saxophone against a wall or a corner.

Your band needs a PA system.

The LJ has a rear port. From the back, it reminds me of a cocked wah pedal. But, it's worth a try when there's a wall available.

[nevershouldhavesoldit]

I get stuck with the notion that dividing the amp's power among two speakers doesn't somehow reduce (halve?) the power to each. That both speakers could be at the original SPL of the internal speaker sounds like magic. What am I missing?

And, then, if reducing the speaker impedence is effective (louder and still sounds good) why didn't the manufacturer do that with the internal speaker?

One other thing. What happens if I run two identical LJ's simultaneously? My pedalboard, an ME80, has left and right outputs (they imply stereo, but they're identical). Do I get more volume from two amps than amp + external speaker cab?

That’s 3 questions - you only get one free one per post

But seriously folks……

1) The only way to answer this accurately is to do the math. Adding a second speaker with the same impedance in parallel will reduce the wattage being dissipated (i.e. transduced into other forms of energy - acoustic, heat etc) by each of them compared to the power that one with half the impedance would dissipate as the only load in the circuit. So a pair of 8 Ohm speakers in parallel will still only be dissipating the rated power of the amplifier together. They do not each turn the full rated output of the amplifier into sound, and they will not be louder together than a single 4 Ohm driver.

If an amplifier is able to pump X watts continuously into a given load, it will do so regardless of the number of resistive elements in that load. To keep the math clean and simple, let’s use an amp rated to push 16 watts continuously through a 4 Ohm load with a full frequency signal. The load in our model is a pair of 8 Ohm speakers wired in parallel. We’ll assume an ideal circuit in which there’s no other resistance, inductance, impedance etc to factor into the equations. This assumption simplifies the model, and the extra factors would only change the numbers by a very tiny amount.

The voltage drop across each of multiple resistors in parallel is the total voltage of the source divided by the number of resistors. Watts = amps squared x Ohms. So a 16 watt amplifier that’s pushing its full rated output current through a 4 Ohm load (which is the combined resistance of two 8 Ohm resistors in parallel) is pumping 2 amps through the circuit with an electromotive force of 8 volts.

The current flowing through the entire circuit is 2 amps, and it’s flowing through both voice coils in our model. Each of the two 8 Ohm speakers is dropping half of the voltage (8 volts / 2 = 4 volts) across its 8 Ohm voice coil in order to push those 2 amps of current through. Since power in watts = current in amps x force in volts, each speaker is dissipating 8 watts. Full rated power (16 watts in this case) is only achieved by both together, not individually. If a single 4 Ohm speaker is used, the current is still the same 2 Amperes. So the power being dissipated by the 4 Ohm voice coil is still 16 watts (8 volts x 2 Ohms).

In an ideal system like the above model (i.e. one that has no other power losses and is 100% efficient), doubling the output power of an amplifier in watts increases SPL at rated power by 3 dB. Halving it cuts dB by 3. And the sum of two sound sources each putting out X dB is X+3 dB. So amps that can double their output into 4 Ohms compared to 8 will be 3 dB louder into the 4 if all else is the same. Many traditional amp circuits (class A, A/B, B) with adequate power supplies can put twice the wattage into half the load if they don’t have transformer coupled outputs.

But modern class D and other small amps with efficient power supplies can’t do that because their power supplies are switched for efficiency and lack serious capacitance. The jump from 45 to 60 watts with half the load impedance in the DV Marks is typical of these - the increase is far from double. So you get a minor bump of a dB or 2. Add that to the better dispersion from multiple drivers and you get a slightly louder amp.

2) Amplifiers that can drive low impedance speakers have to have more robust power supplies because lower load impedance means higher current flow. And speaker components like voice coils, bobbins, cones, suspension etc all have to be tougher to handle twice the power. This means more complexity, more cost, and more weight. Also, providing an external speaker jack would be problematic because the amplifier would have to be able to drive 2 Ohm loads safely and cleanly. So there are no compelling reasons to use single 4 Ohm drivers in guitar amps and it would drive up costs.

3) Two amps turn twice as much electrical energy into sound as one does. From #1 above, you now know that even with a jump from 45 to 60 watts when connecting a second 8 Ohm speaker to a LJ, you won’t gain more than a dB or two. If you use two LJ amps together, you’ll pick up an extra dB or two over using an extension cab on one. But you still won’t gain more than 3 dB plus the added dispersion because 80 dB + 80 dB = 83 dB. 90 dB + 90 dB = 93 dB. 100 dB + 100 dB = 103 dB. Etc etc etc.

[rpjazzguitar]

That’s 3 questions - you only get one free one per post

But seriously folks……

1) The only way to answer this accurately is to do the math. Adding a second speaker with the same impedance in parallel will reduce the wattage being dissipated (i.e. transduced into other forms of energy - acoustic, heat etc) by each of them compared to the power that one with half the impedance would dissipate as the only load in the circuit. So a pair of 8 Ohm speakers in parallel will still only be dissipating the rated power of the amplifier together. They do not each turn the full rated output of the amplifier into sound, and they will not be louder together than a single 4 Ohm driver.

If an amplifier is able to pump X watts continuously into a given load, it will do so regardless of the number of resistive elements in that load. To keep the math clean and simple, let’s use an amp rated to push 16 watts continuously through a 4 Ohm load with a full frequency signal. The load in our model is a pair of 8 Ohm speakers wired in parallel. We’ll assume an ideal circuit in which there’s no other resistance, inductance, impedance etc to factor into the equations. This assumption simplifies the model, and the extra factors would only change the numbers by a very tiny amount.

The voltage drop across each of multiple resistors in parallel is the total voltage of the source divided by the number of resistors. Watts = amps squared x Ohms. So a 16 watt amplifier that’s pushing its full rated output current through a 4 Ohm load (which is the combined resistance of two 8 Ohm resistors in parallel) is pumping 2 amps through the circuit with an electromotive force of 8 volts.

The current flowing through the entire circuit is 2 amps, and it’s flowing through both voice coils in our model. Each of the two 8 Ohm speakers is dropping half of the voltage (8 volts / 2 = 4 volts) across its 8 Ohm voice coil in order to push those 2 amps of current through. Since power in watts = current in amps x force in volts, each speaker is dissipating 8 watts. Full rated power (16 watts in this case) is only achieved by both together, not individually. If a single 4 Ohm speaker is used, the current is still the same 2 Amperes. So the power being dissipated by the 4 Ohm voice coil is still 16 watts (8 volts x 2 Ohms).

In an ideal system like the above model (i.e. one that has no other power losses and is 100% efficient), doubling the output power of an amplifier in watts increases SPL at rated power by 3 dB. Halving it cuts dB by 3. And the sum of two sound sources each putting out X dB is X+3 dB. So amps that can double their output into 4 Ohms compared to 8 will be 3 dB louder into the 4 if all else is the same. Many traditional amp circuits (class A, A/B, B) with adequate power supplies can put twice the wattage into half the load if they don’t have transformer coupled outputs.

But modern class D and other small amps with efficient power supplies can’t do that because their power supplies are switched for efficiency and lack serious capacitance. The jump from 45 to 60 watts with half the load impedance in the DV Marks is typical of these - the increase is far from double. So you get a minor bump of a dB or 2. Add that to the better dispersion from multiple drivers and you get a slightly louder amp.

2) Amplifiers that can drive low impedance speakers have to have more robust power supplies because lower load impedance means higher current flow. And speaker components like voice coils, bobbins, cones, suspension etc all have to be tougher to handle twice the power. This means more complexity, more cost, and more weight. Also, providing an external speaker jack would be problematic because the amplifier would have to be able to drive 2 Ohm loads safely and cleanly. So there are no compelling reasons to use single 4 Ohm drivers in guitar amps and it would drive up costs.

3) Two amps turn twice as much electrical energy into sound as one does. From #1 above, you now know that even with a jump from 45 to 60 watts when connecting a second 8 Ohm speaker to a LJ, you won’t gain more than a dB or two. If you use two LJ amps together, you’ll pick up an extra dB or two over using an extension cab on one. But you still won’t gain more than 3 dB plus the added dispersion because 80 dB + 80 dB = 83 dB. 90 dB + 90 dB = 93 dB. 100 dB + 100 dB = 103 dB. Etc etc etc.

First off, Wow! That was clear as a bell. Thanks so much for taking the time to respond with such clarity and detail! Very kind of you to do that.

Take home message seems to be, a passive external cabinet will increase volume, but not so much that it will be clearly noticeable (but with better dispersion/flexibility). But, a second LJ would be likely to produce a noticeable increase in volume.

GC is selling an Alto 8 inch TX208 with 150 "rms" for $99. I like the price and the weight, under 13lbs.

They sell several more powerful 8" units. The TX308 is $119 listed at 175 watts "continuous". Same weight, so it's probably the same speaker as the 208 with a different amp. I think the more powerful units than that one are about 20lbs, which I wouldn't mind avoiding.

And, it will probably work pretty well for vocals,

GC has a 45 day return privilege.

I'm aware that power numbers are to be digested with a box of salt. But, maybe this is a pretty good solution, if it sounds okay.

Reg uses an Alto as an enhancer (don't know which) and sounds awesome.

[Gitterbug]

If those situations where you need more power include big bands, I advocate an upright extension cabinet such as a TOOB 12J or even Metro 6.5FR II. These are articulate 98/94dB speakers spreading the comping sound evenly to band members. The original speaker can then address the audience only (or be shut). Much as I have read about LJ (even had an early sample), I don't recall any technical data on the stock speaker but it's hardly as sensitive as the Jensen Tornado or even the SICA 6D 1,5SL.

One caveat: never connect/disconnect the extension cab when the amp's power is on. Thanks to the arcane phone operator plugs and jacks we are using, there will be a momentary short on insertion and removal. I've seen a LJ making a bang and emitting blue smoke on receiving an extension cab.

[Stringswinger]

I have used my Blu 6 and my Bud 6 in some very loud rooms when playing with a horn player and a drummer. It is amazingly loud for it's size (I do use a wedge to tilt it so that I can hear myself better). I know they are not cheap, but it makes the gig a one trip load with great tone and headroom to spare.

Problem solved.

[omphalopsychos]

Bud 6 is plenty loud. Worst case you can plug it into an external cab. I love this one, vertical 1x12 with a 75w Tone tubby Nashville alnico.

Damned forum always rotates my pics but here you go.