Valve amp sound issue

[Pow_22]

Last night at rehearsal we played a little louder than usual, not thrash but just a little cranked. I run my Sound City 120 through a fender bassman 2x15 and last night was using my flats loaded P bass. I had the volume at about half way and obviously got the usual valve 'fuzz' or break-up. I knew id get this but to think i was getting loads of it at only half volume (i say only but i know this is pretty loud). It has recently come back from Dave Lunt who gave it a full service, replaced some caps and a pre-amp valve. The valve was a like for like replacement. MY question is do SC's always break up at this kind of level and is there anything i can do to get it a little clearer at this level. Dont get me wrong, i love the valve break-up and fuzz but would just like a little more clean headroom before getting all down and dirty. Could it be i need to look at my cab? Would 2 15's be making my ampo work harder (as in with say a 6x10 would i get more 'volume' without cranking the amp so high?)

[Pow_22]

Any chance a mod can move this to the amps section for a cack handed valve newbie please?

[geoffbyrne]

Assuming your pre-amp valves ar 12AX7 types, you'll get more headroom by substituting them with *proper* 5751s. Beware, as a lot of perceived 5751s are 12AX7s that failed the QC test. They are not the same valve. The penalty is a small loss in overall volume. But no doubt, there will be Sound City experts along soon who will probably advise you better than I.

G.

[Mr. Foxen]

Putting ECC81 into the three tone slots (three middle ones) will drop the gain. But remember the tone control are more linear than most valve preamps, so you can just dial back the bass mid and treble by the same ampount, and turn up the volume. Also, check there is an ECC81 in the phase splitter (on the right with the amp facing you). An ECC83 in there gives you the Electric Wizard breakup sound, which lots of people do.

[Pow_22]

Cheers for the help. I did consider switchin out the pre-amp valves for something less gainy but had also read lots of comments elsewhere on the SC's 'unique' eq so i think ill have a play with that first. My settings are usually (as you look at the amp front). Volume about 1-2oclock, Bass at 3o'clock, Mid at 1 - 2 oclock and treble on about 12'oclock. I use the normal input as opposed to brilliant and leave the presence at 12'oclock too. Ill try and turn them all down equally and boost the volume a little and see if that helps. Ive always been crap at eq'ing (even on solid states), you'd think id have the hang of it by now but like i say i believe the SC is a different beast so my 'usual' amp settings may not apply to SC

Edited January 6, 2012 by Pow_22

[bertbass]

I don't like the sound of Sound City 120s. The reason being, I was lead to believe, is that they have an active eq as opposed to passive eq which all the the other valve heads that I used had / have. This was in the 60s and early 70s. It would also probably explain why I don't like SS amps very much. I don't know, but as passive eq only removes frequencies, how about setting all the tone controls at 12 o'clock, which should be flat, and only turning them down to get your sound. Never know, it may well work well.