low watt harp amp

[John]

Hi fellas. A buddy wants a small amp he can take with him when he has small-room gigs, suitable for harp as well as guitar. He's got a DR that's just too much for a lot of places. I have just started researching, but here are my thoughts so far. I'll use 6SL7 for the preamp, and either a 6V6 or 5881 for the power tube.


Dual inputs, 1 low impedance for the harp (is this correct thinking?)


Switchable cathode caps for the preamp - big for the harp, smaller for the guitar.


If possible, (careful layout/shielded wire), make the coupling caps switchable as well. Something big-.1/.22 or even .47 for the harp setting, then the standard .01 for guitar setting.


And I'd really like to incorporate solid state reverb using the Belton Brick. The power supply part will be easy, but I think I have to be very careful with placement, and routing the wires to avoid noise issues.


And the speaker. I was thinking 8", but I read many comments that prefer a 10". I believe I'll also do an external speaker jack to allow flexibility anyway.


All switches will be manual. The plan is to keep things as simple as possible, while still having it be somewhat versatile. I believe I'll go with a James TS.


This is in the very early planning stages, I doubt I'll begin building before mid summer, so I have lots of time for research, and hopefully get it right the first time. Any thoughts, opinions, or criticisms are, as always, welcome.


Thanks!

[Willabe]

A buddy wants a small amp he can take with him when he has small-room gigs, suitable for harp as well as guitar. He's got a DR that's just too much for a lot of places.

Hi John,

I would say not enough information to give suggestions.

1. What kind of music, guitar clean, dirty/distortion, both?

2. What kind of harp? Dirty/electric with a bullet type mic cupped in his hands OR clean/acoustic with a mic through the house PA on a mic stand no hands. (I'm thinking electric 'blues harp' because he want's an amp to play both guitar and harp through?)


                     Brad     

[John]

Hey Brad, he plays mostly blues, lots of old blues actually, stays pretty clean w/ some overdrive on the guitar. He's a good harp player, plays the harp and guitar at the same time (uses a "rack", I think it's called). I've only ever seen him play into the same mic he sings into.

[Willabe]

I've only ever seen him play into the same mic he sings into.

Ok, then if he's playing harp in the 'rack' (that's the right term) through the house PA along with his vocals, then you don't need to consider voicing the amp for harp.

That will solve a lot of troubles.


                   Brad     

[John]

I'm not talking about playing through a house PA. He wants something for small rooms. Coffee shops, classrooms,  that sort of thing. To simplify, for a harp circuit, I want larger coupling caps, lower impedance at the input jack, and large K bypass caps, is that correct?

[Willabe]

I'm not talking about playing through a house PA. He wants something for small rooms. Coffee shops, classrooms,  that sort of thing. To simplify, for a harp circuit, I want larger coupling caps, lower impedance at the input jack, and large K bypass caps, is that correct?

OK, no house PA.

Well if a DR is too much then the next typical size amp down is a PR but to the human ear they sound pretty close in volume.

Next would be a Champ type amp.

Or maybe you could lift 1 of tubenits cathode bias 6V6/6K6 power amp outputs and put a standard Fender dual channel pre/PI in the front.

I used to play a lot of harp and I've never heard of using bigger coupling caps for a harp amp but you could try different caps and tune it for him?

Also might be easer for you and him to just use/buy a high Z mic? Or use a low Z to high Z transformer that plug in line with the mic cable. There's a number of them made for that purpose.


                      Brad                      

[John]

okie dokie. Thanks!