Inordinate amount of amp hiss with F-30

[Jack Dotson]

I'm a newbe to the Boogie community. Bought a F-30 a little over a week ago and really like it. However, when I turn the volume up past 8:00 I start to get hiss which gets progressively worse as I continue to increase the volume. The hiss is in both channels and the only noise I get. No hum, etc., just hiss.

Is this a normal characteristic of the these amps? The GC I bought it from didn't have another in stock so I took the floor model. They did have a F-50 which I tried and did not here the hiss issue with it.

I got the amp for the blow out price as they have been discontinued, but they didn't give me a manual, cover, etc., just the amp and pedal. And I think it's was probably on the floor for some time.

What do you guys think? A bad tube maybe?

Thanks.

 

[MusicManJP6]

hiss is a common issue with this amp. the hiss on mine isn't too bad, but it does get worse as you turn it up. A noise gate like the MXR smart gate might be the only thing that would get rid of it. It has a setting for hiss. I have one that i'll try out on it. In the loop is the only way to filter it out. I actually just thought of this solution. Haha.

I'll let you know if it works...

EDIT: Just tried it - it helps but there is still some hiss. That makes me think the hiss is part preamp and part power amp. At the volumes I usually play it at it's barely noticeable. At gig volumes it would be louder, but so would all instruments, so it wouldn't be a big deal...

 

[Jack Dotson]

I replaced the 12AX7's on both input tubes and PI and still have the same amout of hiss. I'm going to replace the power tubes tomorrow as I also have four spare JJ EL-84's that I can try.

The good news is that the JJ's made a marked improvement. Both channels are now more to my liking. Better note definition, more balanced, creamy distortion, etc. The JJ's have made an improvement in every amp I've tried them in. I really like the character of these tubes.

Anyhow, I'll get to the power tubes tomorrow and see if it helps, but I seriously doubt it. I guess it's just one of those things you have to live with in a high gain amp. And, like you, I keep the volume at levels where it's not a problem most of the time. Just wanted to make sure something wasn't amuck.

 

[MusicManJP6]

I thought the JJ's added some hiss, but i'll give them another go and see what I think the second time.

Don't worry though, all is well with your F...

 

[MusicManJP6]

OK, so I got some time on my lunch break to play with the F-30 some and here's what I did:

Swapped the stock Mesa tubes out for JJ's again. Sounded better - more defined - but added some hum (from my guitar). I think the hum is what I didn't like the first time I tried them. Apparently they are a little higher gain. I was able to turn the gain down a scoach (yes, a scoach) and it was a little better.

Swapped the stock V1 Russian 12AX7 for a Tung-Sol reissue. Didn't notice a whole lot of difference here, but it was maybe yet a little more defined.

Then I started trying to get rid of the hiss. The treble knob was the number one tool to get rid of the hiss. If you are familiar with Mesas, then you know the treble knob is also the most powerful EQ adjustment. It adds more gain as you turn it up since it is first in line after the preamp (I bleeb). Anyway, it seems that you can adjust the treble to get a good mix between tone and hiss. The hiss is still there, mind you, it just changes shape a bit and becomes less noticeable.

Hope that helps!

Also, I swapped out the V30 for a C90 last weekend and now I can run the bass at ZERO and it sounds awesome. Very smooth and rich.