i have a realist pickup on my double bass and recently tried out a Hartke HA350 head. The vavle gave it a very full and warm sound and i am thinking about purchasing it as it also sounds great with bass guitar. i'd be interested to hear if anyone else has any experience with it.

well, I use Hartke Kickback 12", and quite a few other cats up here use too. The few times I used it with my fretless bass guitar it was OK, but works very well with my Barcus-Berry pickup in both my Double Basses. And it´s very portable, which is important to me, being a member of One Trip To The Car-society.

Yeah, I heard a guy playing with a kickback 12" and he sounded great.

I have used my 3500 with my upright and it worked well. The only problem is that the amp gets a little "hissy" at higher volumes. I have switched to a Peavey Mark VI with a JBL115 cab and that is doing the job. But I think overall the Hartke is the better amp. (The Peavey was cheap- hey)

the good thing in Kickback´s design is the shape of the back, which allows you to tilt it like a monitor. When I play with it I always stand as near as possible, so the sound comes up from the speaker and I can hear myself clearly. I have noticed also that I don´t have to use very much volume at any setup and still the bass can be heard anywhere in the place.
Might be because of that or then it just might be something to do with what I play...

I Need some advice..

Wich is better for DB kickbak 10' or kickback 12' ?
I play on a jazz gig an I use a underwood pickup on my Double Bass.

Any advice is welcome.

I use the Hartke kickback 12. I tried the kickback 10, 12, and 15 with my bass, and liked the 12 best. At the time I had a Fishman transducer, and the Hartke was the only one I found easy to get a good amplified sound. The 10 seemed a little thinner and the 15 not as defined a tone. Like Goldilocks, the middle one was just right.

I've read quite a few comments that in general 10" speakers were preferred for DB, but then with the Hartke kickback, the trend seems to be the 12 (based on this post).

Anyway, I use mine for swing and rockabilly and am really happy with the sound and portability.