Real tube amp crankage

SRVan_halen

When a tube amp is cranked, does it get more condensed gain? a tighter sound, and more full? With my Fender Hot Rod at low levels it sounds great, and has enough gain to play Crazy Train with respectable similarity. But when i turn up ( to even 2.5), it kind of spreads out to a more fuzzy and chunky sound ( more zeppelin and Hendrix), much less defined. It doesn't sound as good to me, but this seems to contradict the common belief that a \"cranked tube amp is the greatest thing is the history of everness\" opinion shared by many. Is it possible it's my speaker fuzzing out, and not anything with the rest of the amp?

shredd

You'd have to get a genuine amswer from the tech wiz guys here - g3456? 'taus? Iliace? But my experience is that while solid state amps get louder in a sort of linear way, tube amps get louder in a logarithmic way. That is to say, the response of the preamp and amplification stages react differently to different levels of input, while a S/S amp will tend to be more consistent.

That may not be as accurate an answer as some of these other guys could give...but don't I sound smart? Know any hott women who're into smart guys who like RUSH? 8)

thehootman

When you learn how triode valves actually work everything becomes clear. Good ol' physics always helps.

T L F

What type of tube is in the Hot Rod? Hootman is right that reading up on how amps work will help but I know in my experience, (in the \"real world\") trying different types of tubes helped out dramatically on the amps' response and compression (Which seems may be what your experiencing?.) It seems like your amp is getting 'spongy' when you push the power amp? I don't know, but years ago I had a Peavey Mace that had (6) 6L6GC tubes and changing those out from Sylvanias to Groove Tubes made a dramatic change in the amp. I had similar experinces with other amps...Right now I have a Vox AD that I have a similar spongy/ loose thing with and I correct it with different compression settings....

guitar3456

Every amp will work differently at various volumes

Compression, Saturation, Clipping, and Bias are more of less relative to interaction of the power amp stage, imp transformer, and speaker choice. Some amps can flavor gains at lower volumes and as you open them up they have more natural headroom. Amps biased can contribute to how the amp performs in many ways.

For one, a 5150 is known for it's BEES in a hive sound by many who prefer lower gain amps. It is biased relatively cold, so making the bias adjustment or mod can clean it up some.. or quite a bit. It's also eq'd higher on the treble side.

In any case, the many things the amp design itself contributes to it's sweet spot.. how it reacts and where the sweet points can be for a listener.

In Fender's case, most people also refer to it's natural compression as piggy back effect. That is, the amp as it is raised in volume, creates enough headroom to clean up but have the hard attack you would find on a compressor pedal, thus raising it's ability to react to picking attack etc. It's not a mistake.. it's a design. Most could tolerate 5ft from a JCM800 but many would feel their ears want to pop out of their head with a Fender or Mesa MKIII blaring at them. Any of which have the natural kick as they say. This, along with steady midrange overtones is also why the cut through so well in a live mix.

You could substitute preamp tubes for more gain.
12AT7 is generally the lowest gain and 12AX7 would be appx 4x gain of the 12AT7.