singing sustain .....

[plexidust]

I've come to admire the singing sustain in the amps that have the 'it' factor . I was wondering if anyone had thoughts on how this happens . Perhaps it is a build aproach that can be used in other designs . Not sure what that resonance is but I like it .

[Structo]

I don't know if I could narrow it down to one or two things.
Kind of a sum of all type thing.

I suppose there are some things that help that to happen but believe it or not, some people don't want that in a amp. Or at least too much of it.

From the filtering of the power supply to the gain structure of the stages, how many stages, type of phase inverter, gain of inverter and power tubes all play a part.

The guitar and speakers also enter the picture as well as technique on the guitar.

[UR12]

I'm convinced it is in the fingers

[jelle]

With a brother like you have I'm sure you do.

[RJ Guitars]

I made some tweaks to an amp I built one time by adjusting various resistance values starting at the first gain stage and moving on through the phase inverter. I added trim pots in place of resistors in key places throughout the preamp. I used my ears to listen for what I call harmonic richness as I would hold a note and tweak each trimmer.

When I was finished I had taken a lot of the headroom out of the amp but it would really sing for me. Here is a sound clip and despite my playing the amp was doing it's part wonderfully.

https://tubeamparchive.com/files/spooky ... er_122.mp3

Here is the thread that will tell you more about the details and tweaks. https://tubeamparchive.com/viewtopic.ph ... t=rockster

I have not done it yet but I have no doubts that I could reverse the outcome by tweaking the trimmers to bring out the clean tones in each stage.... since the amp started out pretty clean to begin with.

About the amp - It is basically a Rocket using KT-66 big bottle tubes. If you look at the schematic you'll see that it is very much the same as the old Fender 59 Bassman only using a cathode biased output section. A great amp to tweak and experiment with because it is very forgiving. Using the Octal output tubes allows you a multitube of different output tube options although I think that I could have gotten a similar result doing the same thing with an EL-84 output Rocket build.

rj

[ampdoc1]

I think if you build an Express using all the tips on this site, you'll be as close to nirvana as you're likely to get.

a'doc

[paulster]

For me I think it's about two things really (three if you count the fingers):

One is generating a rich harmonic complexity by the right balance of warm/cool biased stages in the preamp.

Two is generating just the right amount of power supply compression so it doesn't feel spongy and yet allows the amp to help you out by really sustaining the rich, harmonically complex notes you've already created in the preamp.

This sounds pretty much like RJ was getting at with his tweaking methodology.