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Post subject: I Need A Portable Amp For My Keyboard
Posted: Mon Feb 11, 2019 12:44 pm
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I have a little keyboard that I like to write with when I travel. I'm looking for a nice little amp and I'm wondering if anyone has suggestions? Preferably something small that might have Bluetooth technology as well.

I typed in "portable keyboard amp" and these came up. Are these good options or not should I try something else?

Thanks! :)


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Tue Feb 19, 2019 2:03 pm
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dannyrichardson wrote:
I have a little keyboard that I like to write with when I travel. I'm looking for a nice little amp and I'm wondering if anyone has suggestions? Preferably something small that might have Bluetooth technology as well.

I typed in "portable keyboard amp" and these came up. Are these good options or not should I try something else?

Thanks! :)


Are you thinking Bluetooth so you can play your phone through it occasionally for music? The Blackstar Fly 3 might be a good option... though not a Fender product. Fender does make mini amps, but I don't believe that any of them have bluetooth.


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Tue Feb 19, 2019 4:19 pm
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These amps are made for mono guitar input, about 25 millivolt signals. Your keyboard puts out 250 mv and will overload the inputs. Its also stereo usually.
You're looking for an amp with a cd input or a boom box with a stereo aux input. Those are designed for keyboard levels.
Bluetooth has a latency delay and isn't suitable for live playing.


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Wed Feb 20, 2019 1:44 am
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TimsAudio wrote:
These amps are made for mono guitar input, about 25 millivolt signals.

"25 millivolts", eh?

Perhaps you should take a look at this......

http://www.muzique.com/lab/pick.htm

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Wed Feb 20, 2019 11:46 pm
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You will note he is plugging a guitar into a sound card, not a guitar amp. It is unlikely that the input impedance is similar to a guitar input.
He doesn't specify the input impedance and probably doesn't appreciate the different effects of loading between a signal generator's 50 ohm output and a guitar's high impedance output.
For his demonstration, the actual values weren't important, he was describing the attack to decay characteristic . That is constant at any impedance. But guitar tone and voltages change dramatically with different load resistances.

A passive guitar into a standard 1Meg input will only need 10mv rms to drive an Evil Twin or a HRDX More Drive into power tube distortion at mid volume settings. While these practice amps are not as hot, they are in the same range sensitivity-wise.


Amplifier Input sensitivity is rated as the minimum voltage/load needed to run the amp up to clipping.

A guitar output is in the -50dB range, 10 -50 mv rms
A keyboard is in the -10dB range, 250 - 1000mv.
This is the same as line level devices such as audio receivers and cd players. There will be much less overloading if the proper input impedance is used.


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Thu Feb 21, 2019 9:05 am
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When you tire of trying to dazzle everyone with your brilliance, do this:

Connect a Stratocaster to a VTVM by clipping the test leads directly to an instrument cable plugged into the guitar's output jack. Set the meter for ACV and use the 1 volt scale. Briskly strum a position-one E chord and measure the signal strength (any pickup will do, volume and tone control set to max).

Report your findings.

That's how you measure an electric guitar pickup's output.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Thu Feb 21, 2019 9:08 am
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if you want to hit it with a big hammer, Bose S1 Pro...


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Feb 22, 2019 9:29 am
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I think you're trying to compare apples and oranges here.
When I described nominal voltage for the input of a guitar amp, that is not the maximum output voltage of a guitar you're asking for. A nominal volume setting of 6-7 on the guitar gives the best signal to noise ratio.
Your test conditions are appropriate for a musician. You can easily replicate the setup to compare guitars.
As a bench tech, I use a 400 ohm relay coil placed between the strings against the pickup, driven by 1 volt rms audio signal.
The variables introduced by different strings, pickup height, and volume control loading are fixed and knowable, but brisk strumming is an unknowable variable and make this method useless to a technician.

But, using your test conditions with a Strat knockoff, Peavey Raptor,
Centron DVM, 60 Mv rms
Tenma true rms, DVM 48 Mv rms
HP scope, max 400mv peak to peak = 140 mv rms
The levels at 6-7 on the guitar, 25mv rms


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Feb 22, 2019 11:12 am
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Image


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Feb 22, 2019 12:14 pm
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upnorth2 wrote:
Image

:lol:

When I first performed these tests some fifty years ago my findings were......

1966 Strat, stock gray bottom Fender P/U's:
225 mV RMS peak-to-peak (aggregate average between the three pickups)

1964 Gibson SG Standard, PAF humbuckers:
310 mV RMS peak-to-peak (aggregate average between the two pickups)

I also measured our bass player's 1968 Gibson EB-0 (humbucker)
700+ mV RMS peak-to-peak (a plucked open E string was used)

The Hewlett-Packard meter belonged to my Dad.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Feb 22, 2019 4:14 pm
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Ok, Was the HP a scope or a DVM?
When you are specing RMS and P-P numbers together, I'm confused.
Are these p-p values from a scope or RMS values from a DVM? Were the p-p numbers at string drop or an average?
Using 1/2P-P x .707 = RMS, 225mv p-p = 79mv RMS.
With a plucked string, I wouldnt be surprised at 79mv or even 225 mv. A pickup is a high gain transducer and a plucked string would get a lot of action going.


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Feb 22, 2019 4:24 pm
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CRS strikes again!

:oops:
You are correct indeed -- the measurements were peak-to-peak, not RMS.

The meter was an analog H-P, specific model number unknown.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Fri Mar 01, 2019 6:05 am
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Roland


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Sun Aug 18, 2019 9:49 am
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They say acoustic guitar amps work well with keyboards - I’ve never tried it but Fender makes a nice assortment of those kinds of amps. What you probably really need is a powered monitor or two of whatever size you want. I use one or two big powered speakers when I play keyboards out - certainly loud enough to keep up with a couple guitar players with Twins. A vintage keyboard (electric piano, clavinet, combo organ) will sound best through a tube guitar amp anyways - I use a Vibrolux or Pro Reverb


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Post subject: Re: I Need A Portable Amp For My Keyboard
Posted: Sun Aug 18, 2019 3:14 pm
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Sounds like you need to make a trip to the music store and try several variants to me.
I'd be inclined to try the new tone master series, the twin or the deluxe based on your need for volume.


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