long hiatus. 5150 issues and new tube recommendations

[moth_baller]

Re: long hiatus. 5150 issues and new tube recommendations

Any new 6L6GC set will be fine. Plug them in and see and hear how it goes. The bias according to Joey's post is fixed so that if you plug in a 6L6GC it will operate in a safe range. You just don't want the plates in the tubes to start to glow red (not to be confused the normal orange glow of the heater filliments) or anything.



Valve is the term the British use for vacuum tubes. It means it is a tube amp. The Peavy 5150 is based on the great Soldano SLO 100. It's not an exact copy of course but the basic circuit design is similar. The design creates the distortion in the high gain pre amp. The power amp is designed to be fairly neutral and more accurately reproduce the tone already created in the pre amp. You can then control the volume of the power amp using the master volume. It should not need to be stupid loud to sound good although it can get stupid loud if need be. The 6L6GC is a good tube for this design.



Those would be pre amp tubes actually. It probably uses 12AX7s in every position. You can try using lower gain versions of 12AX7s in certain positions to calm down the amount of gain and distortion. A tube such as the 5751 in V1 or V2 will reduce the amount of distortion created in the pre amp. The preamp tubes are usually numbered in order starting with V1 being the one farthest away from the power tubes. V1 is the most important tube affecting the tone in a tube amp.

The one closest to the power tubes is usually the phase inverter tube. Fenders usually use a 12AT7 tube there for more clean headroom. A 12AT7 in the PI increases the headroom (how loud it can go before it compresses or distorts the tone) of the power amp. A 12AX7 there decreases the headroom of the power amp.

Cool. Good info. When I've heard the term valve tossed around it is always from someone British. Makes a lot of sense now.

I didn't know the preamp tubes would what would actually calm it down. I always understood the power tubes were responsible of that. With the distortion created in the preamp that makes sense.

I've heard the name soldano but never heard that the 5150 was based on that amp. I'm not very versed on amps that aren't marshall, peavey, fender or mesa.

I went and looked to see what tubes were in the preamp section. No brand on them. It uses 12ax7 tubes in the preamp. I feel sort of dumb searching for the tube size. It's printed next to the sockets.

[moth_baller]

Re: long hiatus. 5150 issues and new tube recommendations

Yes It's a loose copy of the SLO in the preamp, but does have some extra stuff that refines it a bit, and obviously is a lot more compressed than an slo, enough to make it sound quite a bit different. When the 5150 amps came out, they were, and probably still are, one of the highest gain amps on the market.

trying other tube types is a good plug and play way to adjust your sound, however the only issue you might run into is that some (most) don't bias up well or equally with the peripherals used for one type versus the other, so it won't be an even comparison if you stick a 12au7 in for a 12ax7 with out adjusting its quiescent operating point. Something similar to the 12ax7 like a 5751 is fair game though.

The same goes for using a 12at7 for the PI. You can use one in place of a 12ax7 with out too much issue in the sense that it will work, but you won't likely reap the benefits from doing so. The larger plate loads that most 12ax7's use really push the 12at7 into the most non-linear portion of its grid curves, the biasing at the cathode is off a little as well. To really get the headroom from it you would need to make a few adjustments.

Yes, the gain is pretty crazy on it but I love it. Never a need to own a distortion pedal. Have a metal zone but it's well, a metal zone. Since having the PA running I have no real need right now to attempt to lower it at all.