Structo wrote:Yes, 4K7 is correct for that.
The 6K2 is the stock value.
So 4K7 would give more of a compressed signal, right? I mean, the larger the feedback resistor the more the amp "opens up" - i.e. less feedback. Is this correct?
I guess this is confusing to me.
A while ago I was messing around with the feedback resistor. I had put a 10k pot in my amp and messed around with different values. Eventually I dialied it in to 10k because the amp had the most punch and the least compression. I figured that was a good thing but in retrospect maybe I was wrong. In the second one I built I used the stock 6.2K, and this second amp has a lot more punch and dynamics to it (though I have to turn the gain up a little higher). All around the tone and touch sensitivity of amp #2 is way better than amp #1. Is a smaller feedback Resistor better?
"...there are flying v's and then there are the ones shaped like peanuts..." - my son at age 9
In layman's terms the beauty of the circuit is although it may seem like a brightness or treble booster - the bass and lower mid frequencies that are removed actually free up power bandwidth for the other frequencies to be louder and more responsive
The FB resistor value is dependent on many things: output transformer size, FB cap value, grid couplers, plate voltage to name a few. Make it too big and the control doesn't do much, too small and the control does way too much even when set low. To further complicate matters it's very hard to find the right value with your ears when you don't know if you have the correct value capacitor and very hard to find the correct value of capacitor with your ears when you don't know if you have the right value resistor. By far and away the easiest method is to mimic the values another designer has used for a similiar output configuration with some clipleads to a decade box and a capacitor substitution box and play with those values and hear the changes immediately. Well worth your time if your just doing it on your personal amp to milk that last few % of tone.
Unplugged you should be able to make the note sustain by finger vibrato, i.e. the string rubbing against the fret,it will be somewhat lower in volume than the first few seconds of the sustained note but if you are good at it and have a resonant guitar it will be very audible, practice getting this louder unplugged, THEN PLUG IN. Play long sustained notes. Some amps and preamps tend to MINIMIZE THE DIFFERENCE between the original plucked string volume and the "vibrato-sustained " portion of the note. As a non tech this would be compression and sag in which the input threshold for full volume is still reached by just the vibrato-sustained portion of the note and BLOOM HAPPENS. With high gain amps it is also better to have a softer picking attack than on acoustic guitar to minimize pick noise but also to control the front end attack so it is more balanced to the later portion of the note so we get sax like and flute like and violin like attacks (or non attacks ) and sustain and bloom. I suggest you add an input sensitivity control or use a tube pedal like a radial tonebone to see if you have optimum TRIM (input gain at the very first stage) . A Strat would require a higher TRIM setting than a humbucker equipped guitar to get equal amounts of "BLOOM" . You may be able to add gain at later stages as well but a terrific amp like the Dumble ODS will BLOOM at low volume and be crystal clear even when overdriven, a benchmark for amp design and TONE.
robertkoa wrote:
You may be able to add gain at later stages as well but a terrific amp like the Dumble ODS will BLOOM at low volume and be crystal clear even when overdriven, a benchmark for amp design and TONE.
Besides the above...
Tip #2: drop the pick and start playing with your fingers...you will be amazed at the tones that result one of the original responses to the OP's question pointed out Jeff Beck's ability to basically be Jeff Beck - a huge part of Becks tone is the fact that he doesn't play with a pick.
Tip #2: drop the pick and start playing with your fingers...you will be amazed at the tones that result Wink one of the original responses to the OP's question pointed out Jeff Beck's ability to basically be Jeff Beck - a huge part of Becks tone is the fact that he doesn't play with a pick.
Flesh encourages warmth and bloom Cool
After watching Jeff play the ARMS concert in 85..Threw away the pick...Every time I pick one up and try to use it feel like I just entered a 3 legged sack race with a 1 legged man.. As far as if playing with your fingers helps with note bloom or added warmth etc.. or will make the amp more responsive...To me it's all rather relative...Playing with your fingers does give you a more positive connection with the instrument/ amplifier, translating into a broader range of tones as well as a whole other level of expression... However within that lies a whole other level of positive and negative qualities about an amp and guitar as well..
Like I said it's all relative.. Just on a different level...
Playing with your fingers won't in my opinion help with note bloom!!
Damn it's late... Did any of that make any sence...
Yes guys, good point: another good way to soften front end attack is to use just fingers, so the sustained portion is almost as loud or as loud as the initial (softer, more legato, less transient) attack for more "bloom". It also seems that in rock and blues the guys with really great tones almost always have great finger vibrato. Possible exception Robbie Krieger from the Doors who also played without a pick.Mark Knofler is a good example of someone with lots of "bloom " and sustain and he does it with very low gain (relatively) which indicates to me he's got some really good touch and doing it himself(no pick), but a good or great amp will of course enhance it even more.
robertkoa wrote:Mark Knofler is a good example of someone with lots of "bloom " and sustain and he does it with very low gain (relatively) which indicates to me he's got some really good touch
Yes, he's got a fantastic touch and is a great musician all around. But he also has a good amount of compression going too. Sounds like that to me at least. His amps are quite clean in sense that you're not hearing break-up, but if you're squashing the dynamic range going in, that will help with the "bloom" and bring out the nuances or "touch" if you will.
Getting back for a moment when talking about string vibrato, most guitarists use the bending the string for vibrato.
Violinists (used to be one) use the finger on the string and will modulate the note by wiggling, for lack of a better term, the finger making it slightly flat then sharp in a rapid motion.
You can vary the speed for affect.
Classical guitarists also use this method. It is harder on a fretted instrument than on a fretless one due to the fret anchoring the pitch of the note.
BB King uses this type of vibrato and he has always been associated with that.
Like I said most guitarists move the string side to side for vibrato.
There is no right or wrong way, if it's pleasant to the ear then it is good.
Q for markmalin: Do you have the Vishay-Dale RN65 plate resistors? If not, you should try them.
What I've gleaned from all this is that bloom would be from a very light attack and using vibrato to bring the level up. The wrong amp will fight that and the right one will help.
one of the original responses to the OP's question pointed out Jeff Beck's ability to basically be Jeff Beck - a huge part of Becks tone is the fact that he doesn't play with a pick. 
