talbany wrote:
Greg
I agree the feedback has to start from somewhere It still will be an interesting experiment I want to try to see how much natural sustain the amp has..Chances are it won't feedback as much in another room,, So we will see..
Tony
What makes a great #102 circuit so special is the effect certain areas & notes on the fretboard start to bloom into very "musical" harmonic feedback. And I say musical because #102 has an almost envelope opening like effect. Call it what ever you will, note flipping, bloom, violin tone, etc.
Greg
As your boy Shad states..
With that and having played...um uh amps that closely resemble the circuit topology found in a particular serial number of Dumble (#102 "clones) I can say that I feel that not all dumble circuit have the same quality... Yeah the player can make good things happen but this is a quality that is much more in the amp
The 102 is a wonderful circuit..But that's just part of it..IMO!!
Tony
" The psychics on my bench is the same as Dumble'"
talbany wrote:
Greg
I agree the feedback has to start from somewhere It still will be an interesting experiment I want to try to see how much natural sustain the amp has..Chances are it won't feedback as much in another room,, So we will see..
Tony
Exactly, it's not whether the amp can feedback or not, cause at higher volumes and close pickup approximation most will, even if the amps lead dress doesn't follow the original 1:1.
What makes a great #102 circuit so special is the effect certain areas & notes on the fretboard start to bloom into very "musical" harmonic feedback. And I say musical because #102 has an almost envelope opening like effect. Call it what ever you will, note flipping, bloom, violin tone, etc.
unfortunately I didn't have under hand an amp behaving like yours in all my life
my current hypothesis is that the preamp in a certain way changes the phase of the signal as the signal amplitude changes
I have recently noticed this in the high-plates OD stages while it doesn't happen in the low-plates ones, but I still don't know why...
this is the only thing I can think of explaining such a behavior because, no matter where you stand form the speaker, there will be a point in time where the amplitude decreases to a level where phase is near zero and feedback can occur (with signal leveling around such an amplitude...)
Upon request I dragged the amp and cab downstairs..The amp is sitting in a separate room separated by a partition so virtually no acoustic coupling going on.. The cord is 12 ft clearly stretched out...Master vol on 2 1/2 no lator straight in.. PAB on Delta King Hollow body same licks...Clearly the amp is more picky about which notes it chooses to feedback on and the harmonics generated seems more random..You be the Judge!!
unfortunately I didn't have under hand an amp behaving like yours in all my life
my current hypothesis is that the preamp in a certain way changes the phase of the signal as the signal amplitude changes
I have recently noticed this in the high-plates OD stages while it doesn't happen in the low-plates ones, but I still don't know why...
this is the only thing I can think of explaining such a behavior because, no matter where you stand form the speaker, there will be a point in time where the amplitude decreases to a level where phase is near zero and feedback can occur (with signal leveling around such an amplitude...)
currently I have no way to test this on my own
cheers
teo
Tony
" The psychics on my bench is the same as Dumble'"
Well, that's more or less how my gigging amp behaves at band volumes, except to get it to do that, I will need to turn around and face the speaker -- and sometimes I'll have to make weird contorsions as well to get the amp to sing. Clearly something (good) about your amp, period.
Gil
talbany wrote:Upon request I dragged the amp and cab downstairs..The amp is sitting in a separate room separated by a partition so virtually no acoustic coupling going on.. The cord is 12 ft clearly stretched out...Master vol on 2 1/2 no lator straight in.. PAB on Delta King Hollow body same licks...Clearly the amp is more picky about which notes it chooses to feedback on and the harmonics generated seems more random..You be the Judge!!
I think I don't have any theories as to why Tony's amp behaves that way. If it was a self oscillating thing, I think we'd hear a selected few frequencies the amp favored regardless of the input (i.e., the natural frequencies). Now, to an extent Tony's amp seems to want to come back to a few frequencies more than others, but it feedbacks musically on just about any note. That being the case, it sounds like to me like there could be some coupling going (perhaps due to lead dress, "imperfect" filtering, etc.) on somewhere such that it's easy to get feedback without the need for too much gain.
Gil
llemtt wrote:Gil
I don't get what's your current hypotheses, do you think that the clean preamp (v1a+v1b) is an almost "self oscillating" circuit?
so that when fed by a signal from guitar it starts oscillating by themselves?
ayan wrote:I think I don't have any theories as to why Tony's amp behaves that way. If it was a self oscillating thing, I think we'd hear a selected few frequencies the amp favored regardless of the input (i.e., the natural frequencies). Now, to an extent Tony's amp seems to want to come back to a few frequencies more than others...
You are right, I'm going to "spectrum analyze" Tony's last test to find some evidence of that
Time for 1 more.. Clean channel this time PAB on MV on 3 same guitar.. I am in the room about 10ft away back against the amp.. Real sorry about the crappy playing.. You get the idea.. I don't have a clue!!
Nice clip, nice music room and nice view! Are you close to Blair Witch?
Gil
talbany wrote:Time for 1 more.. Clean channel this time PAB on MV on 3 same guitar.. I am in the room about 10ft away back against the amp.. Real sorry about the crappy playing.. You get the idea.. I don't have a clue!!
Yeah!!. I wish..My ass is above the garage Wife insisted we use it as a sitting room..You know the room your wife spends all your money buying nice stuff for and you never sit in it.. Just got the place so far diggin it!!..Richmond Va..
Gil Where the hell is Blair Witch!!
Tony
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Last edited by talbany on Fri Mar 09, 2012 8:51 pm, edited 1 time in total.
" The psychics on my bench is the same as Dumble'"
You didn't see the movie?! Typical DC area woods, like right outside your window.
Your house looks lovely, congrats!
Gil
talbany wrote:
nice music room
Yeah!!. I wish..My ass is above the garage Wife insisted we use it as a sitting room..You know the room your wife spends all your money buying nice stuff and you never sit in it.. Just got the place so far diggin it!!..Richmond Va..
Gil Where the hell is Blair Witch!!
Tony
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Oh yeah I heard of the movie. Never saw it though..I didn't know it was filmed in Fredrick County..I just came from Maryland (St Charles Co) Fredrick is a bit north..Let me tell ya.. Mighty dang creepy in dim dare woods.. Fredrick Co Md not far from here couple hours..
Thanks &
Cheers Back!!
Tony
Last edited by talbany on Sat Mar 10, 2012 2:52 am, edited 2 times in total.
" The psychics on my bench is the same as Dumble'"
It still will be an interesting experiment I want to try to see how much natural sustain the amp has..Chances are it won't feedback as much in another room,, So we will see..
my hypothesis goes to the trash 
Wife insisted we use it as a sitting room..You know the room your wife spends all your money buying nice stuff for and you never sit in it.. 
Just got the place so far diggin it!!..Richmond Va..