Driving a powered speaker with a Boss ME-80 pedalboard

[rpjazzguitar]

I tried going from the ME80 to an Alto 110. This required turning the Alto up almost all the way and it sounded terrible.

My understanding is that the ME80 puts out too little voltage for the Alto. That is, the ME80 usually goes in front of the amp and the signal coming out of the ME80 is similar in voltage to the signal coming out of the guitar. That is, unless you engage the FX to amplify the signal, but that changes the tone.

It may be that there are different voltages assumed by "consumer" and "pro" line levels. Well, there are, but I'm not sure that's the issue.

The Alto manual claims a mic preamp, but it sounded awful at any useful volume for the guitar. Bass frequencies went ballistic.

I assume that this situation requires a preamp between the ME80 and the powered speaker.

My question is whether a typical DI box can accomplish this? Is there amplification in a typical DI? Is impedance matching enough?

Can you help me understand this?

[starjasmine]

Update to the update: the specs for the Alto 110 seem to indicate that you could just plug your hi-z line out from the ME80 into the female TRS connector on the Alto. Have you tried that? Maybe you don't need a DI at all, unless you need lo-z for a really long cable run....
=========================================

• Check for an impedance mismatch: no power and lousy sonics are the classic symptom.
  UPDATE: A DI might in fact do the trick; a line level in is 10k ohms but a lo-z mic in is 1500 ohms.
• How efficient is the Alto 110? Years ago, I tried to create a lightweight stereo rig out of a Digitech multifx, a half-rackspace Stewart stereo power amp, and the two smallest, lightest speakers I could find: RAMSA 4" or 5" IIRC. Same deal: not very loud, even when cranked. I contacted Stewart, who indicated that the amp should be face-meltingly loud and suggested I try some other speakers. I swapped in my PA mains for the RAMSAs while on the phone with Stewart tech support and OMFG was that thing loud. And clean! The RAMSA speakers were just horribly inefficient.
• You might just try another powered speaker if that's convenient.
• I recall seeing Rob Marcello demo the ME80 with a pair of Roland Cubes at NAMM years back and it always sounded great (well, as great as anyone can sound on the floor of NAMM!) Maybe that's an alternative to a powered speaker - the Cube is pretty lightweight and it sounds good. Yeah, Rob is not really a jazz guy, but still a treat - and his clean tone with that rig was good. (I am assuming that the whole point of this exercise is to lose some tube-amp pounds without losing too much tone... or you'd just lug the tube amp )
  
  

Good luck. Let us know how it goes!


SJ

[nevershouldhavesoldit]

A quick look at the ME80 specs finds that the input and output voltages are the same. The rated -10 dBU for both equals about 225 mV, which is about the same output level as a classic style humbucker. There is no preamplification in the ME80. It’s a zero gain device that is not able to drive a power amp without input voltage amplification (i.e. a preamp) in the circuit.

It will drive Roland cube amps because they have preamps on board. The Alto 110 does not, so the ME80 and the Alto are not usable together without a third device to add front end gain.

[John A.]

I tried going from the ME80 to an Alto 110. This required turning the Alto up almost all the way and it sounded terrible.

My understanding is that the ME80 puts out too little voltage for the Alto. That is, the ME80 usually goes in front of the amp and the signal coming out of the ME80 is similar in voltage to the signal coming out of the guitar. That is, unless you engage the FX to amplify the signal, but that changes the tone.

It may be that there are different voltages assumed by "consumer" and "pro" line levels. Well, there are, but I'm not sure that's the issue.

The Alto manual claims a mic preamp, but it sounded awful at any useful volume for the guitar. Bass frequencies went ballistic.

I assume that this situation requires a preamp between the ME80 and the powered speaker.

My question is whether a typical DI box can accomplish this? Is there amplification in a typical DI? Is impedance matching enough?

Can you help me understand this?

Typical DI's do not provide gain, only impedance matching. The specs here imply that it has a headphone output. That might work into your powered speaker, thoughy ou might have to experiment with both a standard mono patch cord and a TRRS cable.

[rpjazzguitar]

Typical DI's do not provide gain, only impedance matching. The specs here imply that it has a headphone output. That might work into your powered speaker, thoughy ou might have to experiment with both a standard mono patch cord and a TRRS cable.

Thanks. I see that the output spec and the headphone output spec are the same -10dbu.

I assume that means that headphones can run off of a consumer line level signal. Is that correct?

Nevershould's post indicated that the ME80 doesn't put out enough volts, which is certainly what it sounded like.

And yes, I was wondering about using the ME80 into a powered speaker as a way of getting more volume than my Little Jazz.

The only time I've done anything similar was when I used the LJ as a front end to a PA system. Which sounded great. The LJ has an XLR output for that purpose. The PA was a Yamaha Stagepas,which has a mixer, which, presumably, supplies preamplification.

I could also plug the ME80 into a simple mixer and then into the powered speaker. That would probably sound okay, but it's three more things to carry, counting the power supply and extra signal cable.

[John A.]

Thanks. I see that the output spec and the headphone output spec are the same -10dbu.

I assume that means that headphones can run off of a consumer line level signal. Is that correct?

Nevershould's post indicated that the ME80 doesn't put out enough volts, which is certainly what it sounded like.

And yes, I was wondering about using the ME80 into a powered speaker as a way of getting more volume than my Little Jazz.

The only time I've done anything similar was when I used the LJ as a front end to a PA system. Which sounded great. The LJ has an XLR output for that purpose. The PA was a Yamaha Stagepas,which has a mixer, which, presumably, supplies preamplification.

I could also plug the ME80 into a simple mixer and then into the powered speaker. That would probably sound okay, but it's three more things to carry, counting the power supply and extra signal cable.

I've never tried to run headphones off a line-out, so I can't speak to whether that would work. But i have taken the headphone output from many different devices and plugged that into line-ins of mixers, aux-ins on guitar amps, audio components, etc., and it works. If you turn the headphone level up to high you'll get distortion, so it can take some experimentation to get it working OK, but it generally does work OK.

[nevershouldhavesoldit]

Thanks. I see that the output spec and the headphone output spec are the same -10dbu. I assume that means that headphones can run off of a consumer line level signal. Is that correct?

Nevershould's post indicated that the ME80 doesn't put out enough volts, which is certainly what it sounded like.

Here’s where it gets crazier. The usual reference “line level” signal strength is -10 dBV, with 0 dB being 1 volt into any impedance. On this scale, -10 dBV = 775 mV, which is enough to drive most non-commercial amplification.
But 0 dBv (lower case v) references to 775 mV into a 600 Ohm load.

Then along comes the dBu scale, on which 0 = 775 mV into an “unterminated load”. This was chosen by the relevant authorities for pro audio because it pushes a 1 milliwatt power level through a 600 Ohm load, and 600 Ohms has been the most common input impedance for pro audio power amps for a long time. But “line level” for pro audio is +4 dBu, which is 1.228 V. I suspect (but can’t confirm yet) that the Altos use the pro reference scale.

As for using the headphone outlet, there’s a small amplifier chip in there to drive it - but there’s no output level spec. So it might work, but I doubt that it will put out enough voltage to drive the Altos. It can’t hurt anything but your ears to try.

[pingu]

Great info here ....
thankyou NeverS

note that some powered speakers
have a guitar/instrument input

I heard a Bose S1 with a mic’d fiddle the other day and it sounded very good indeed ....
(and loud enough)

[rpjazzguitar]

Here’s where it gets crazier. The usual reference “line level” signal strength is -10 dBV, with 0 dB being 1 volt into any impedance. On this scale, -10 dBV = 775 mV, which is enough to drive most non-commercial amplification.
But 0 dBv (lower case v) references to 775 mV into a 600 Ohm load.

Then along comes the dBu scale, on which 0 = 775 mV into an “unterminated load”. This was chosen by the relevant authorities for pro audio because it pushes a 1 milliwatt power level through a 600 Ohm load, and 600 Ohms has been the most common input impedance for pro audio power amps for a long time. But “line level” for pro audio is +4 dBu, which is 1.228 V. I suspect (but can’t confirm yet) that the Altos use the pro reference scale.

As for using the headphone outlet, there’s a small amplifier chip in there to drive it - but there’s no output level spec. So it might work, but I doubt that it will put out enough voltage to drive the Altos. It can’t hurt anything but your ears to try.

This info is much appreciated.

Might you be kind enough to explain how impedance gets involved? If I understand this much, the ME80's output prefers to see a high impedance input (usually the guitar amp), but isn't 600 ohms a low impedence?

I think I understand the voltage issue with the different standards for line level, but I don't understand the issues related to impedance.

Thanks in advance.

[Cunamara]

Maybe put something like an inexpensive ART Tube MP mic preamp between the pedalboard amp the Alto?

I also have an Alto TS110a and was able to successfully drive that using a Zoom MS100BT multi-pedal, which seems to put out enough voltage to the Alto, and gigged with that a number of times. It sounded pretty good and was convenient for getting in and out of gigs; the line out from the back of the speaker to the PA was also helpful as the pedal handled all of the tone shaping, so the PA sound was the same as I was getting out of the speaker. I thought it had less beaminess and better dispersion than a standard guitar amplifier, but in the end of the convenience of just taking a combo amp to the gig won out.

[Brooks]

If you are just playing guitar thru it, ditch the Alto and get a guitar combo, it will work much better.

[nevershouldhavesoldit]

Maybe put something like an inexpensive ART Tube MP mic preamp between the pedalboard amp the Alto?

I also have an Alto TS110a and was able to successfully drive that using a Zoom MS100BT multi-pedal, which seems to put out enough voltage to the Alto, and gigged with that a number of times. It sounded pretty good and was convenient for getting in and out of gigs; the line out from the back of the speaker to the PA was also helpful as the pedal handled all of the tone shaping, so the PA sound was the same as I was getting out of the speaker. I thought it had less beaminess and better dispersion than a standard guitar amplifier, but in the end of the convenience of just taking a combo amp to the gig won out.

The ART is a great preamp for this - I’ve used one for years. It’s tube-y, quiet, clean and musical in sound and feel.

I have a Zoom MS60B, a true preamp & effects pedal that (like yours) works well because its output at rated distortion is +5 dBm. The dBm scale is another measure of signal level, this one expressing voltage to push 1 milliwatt through a given impedance. The Alto’s input impedance is 15 kOhms, so +5 dBm = about 7 volts.

[rpjazzguitar]

If you are just playing guitar thru it, ditch the Alto and get a guitar combo, it will work much better.

I'm just trying to understand why it didn't work when I tried it a few years back. Just voltage mismatch or is impedance mismatch part of it? It's an academic question, not about the gear I'm actually using at present.,

For the playing I do, I mostly use a DV Mark Little Jazz (which sounds great through the powered speaker btw, although I've never brought one to a gig).