SImple amp for F20

[Doug]

On 07/06/2014 08:57 PM, Robert Moskowitz wrote:
>
> On 07/06/2014 08:45 PM, Doug wrote:
>>
>> On 07/06/2014 06:13 PM, Robert Moskowitz wrote:
>>> I am looking for a simple amplifer program.
>>>
>>> I have looked at audacity, but I would have to be 'recording' to get 
>>> 'playthrough'.  There is supposedly a .vst plugin, but I have not 
>>> found it yet.
>>>
>>> This is for my wife to be able to have a simple amp (using my little 
>>> Asus Eee900) for when she is playing her guitar and needs a bit of a 
>>> boost.
>>>
>>>
>> As a part-time musician, I would suggest that playing guitar over the 
>> typical computer speakers is going to sound terrible, if you make it 
>> work at all.
>> (It may be difficult to make it work, because a guitar pickup, 
>> whether magnetic or acoustic, is at microphone level, and the 
>> computer sound programs
>> would tend to resist putting a mic input out thru local speakers, due 
>> to acoustic feedback concerns.)
>
> Thanks for the valuable response.
>
> We have a real old pickup, her brother's from some 30 years ago. I 
> have a USB sound card (Sabrent) that I was going to use for the I/O, 
> then some small external speakers.  Just something small that she 
> could take when it was a little larger venue than a living room.
>
>>
>> However, there are relatively cheap solutions that do not involve a 
>> computer at all.
>>
>> The cheapest is to look for a low-powered guitar amp on Craig's List, 
>> or at local garage/yard sales. I have found two, so far, one of which 
>> is maybe 10 Watts
>> and would work fine. I paid $10 for it.  The next cheapest is to get 
>> a student amplifier from a commercial source.  Looking at the 
>> catalog, "Musician's Friend"
>> for last December (the latest one I have) on the inside back cover 
>> there is a Starcaster Guitar Amplifier, "The perfect amp for 
>> beginners with 15 watts
>> of power."  The sale price was $39.99. They claim it lists for $99 
>> MSRP. MF stock number is H96133.
>> I don't know if this is still available, but something like this 
>> probably is. ON the page, it says, Visit *musiciansfriend.com/dealcente
>> *(I don't actually use the little amp for guitar, I use it as a 
>> monitor for a record player. I have a 1959 Fender Bassman that I use 
>> for gigs on electric
>> piano and guitar. Your wife should not try to actually play a gig on 
>> a little bitty amp like I have described.)
>
> Whatever I get has to be RF shielded.  We live 600' from a 700' FM 
> tower with 5 stations at max wattage.  A lot of unshield stuff just 
> does not work in our home (we fought the tower, but there is a 400' 
> near it that was here before the community was build up).
>
>
It's possible that a small transistorized amp will be "sort of" 
shielded--it may be enclosed in a metal box.  If you have a problem, 
there are a couple of simple
things to try: get some snap-on ferrite shield beads. They cost about 
$2-3 each. put one or two around the AC poser cord right where it enters 
the amplifier chassis.
Put one or two around the wires to the speaker(s). Put one or two around 
the guitar cord, just at the plug where it plugs into the amp.  Put a 
couple at the other end of the
guitar cord, where it plugs into the guitar.  Unfortunately, the next 
things require some surgery on the inside of the amplifier. If you're 
not into that sort of thing,
you should probably try and find somebody who is, like an electronic 
tech or a radio amateur. He will experiment with some small capacitors 
at judiciously selected
point, like right at the input jack, and right where the speaker wires 
exit the chassis, and probably from the AC power line inputs to chassis, 
where the lines come into the chassis.
At the speaker wires and the AC lines, I'd start with 1000pF. That's 
likely too big for the guitar input port, so maybe 100pF at that 
point--you'd have to listen and see
if it louses up the treble.  There are also some small ferrite toroids 
that could be installed on some wires inside the amp.  That would 
involve unsoldering the wire, slipping the
core over the wire, and soldering it back.  Killing RFI is as much art 
as it is science, so some trial and error is to be expected!
If you install all the suggested fixes and it works, try removing one at 
a time, and see if that's the sensitive point. If you see no difference, 
you might as well save that ferrite
for some other application.

Another idea: play in the basement, if you have one!

--doug