Because the Harp Pro does not come with an instruction
manual I don't know what to call the "mystery" knob
on the back with no name. I believe that this controls the voltage
to one of the tubes. What it does is "fatten" the
tone. You have to experiment with the proper balance of the
"mystery" knob and the volume control to get "your
sound". It does work though and this is one of the main
features of this amplifier and a reason for its versatility.
It is very difficult to describe sound and tone
in words. You really have to play and listen to an amplifier.
Also, your microphone and playing technique has a dramatic effect
on the sound you get.. out of your amp. I have several microphones
but prefer to use an old Shure 520 bullet with a controlled
reluctance cartridge. Through the Harp Pro I can mimic the tone
characteristics of Taj Mahal on "She Caught The
Katy". Adjust the mystery knob and I can get that fat,
Little Walter tone. Want to sound like a trumpet or muted horn
- no problem. Another characteristic I recently discovered was
that because it is less prone to feedback you can add more treble
and your chords and octaves really sound fresher and more complex.
Unfortunately there are few or no retail stores
where you can try this amp out yourself. You buy straight from
the manufacturer, so unless you have a friend with a Harp Pro
or you make a trip to the factory in New York you'll have to
"pay now and play later". At $695 US plus shipping
this is a leap of faith. However, I am now glad that I took
To summarize, here are a few of the Pros and Cons
of buying a Harp Pro:
-Well made, will probably last a long time.
-Small, compact, attractive.
-Flexibility to adjust the tone at any volume..
-Good company service, fast delivery, quick response to questions.
-Loud for its size.
-inability to try before purchase.
-not loud enough for some gigs (unless miked).
These cons will probably be insignificant after purchase. If
you really need a 60-100 watt amplifier buy something else.
Well that's all folks! I need to go and practice some more if
I ever want to sound like a Harp Pro.