102 Feedback City

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Bob-I
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Re: 102 Feedback City

Post by Bob-I »

Structo wrote:Just so we're clear when we say V1a, we are talking first stage right?

Because most Dumble amps are wired with the "b" side first.
That's not entirely accurate. the first triode in a 12AX7 is pins 6-7-8 the second triode is pins 1-2-3. Check the datasheets like this one http://www.hifitubes.nl/weblog/wp-conte ... -12ax7.pdf

Apparently this is for lowest noise.
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Structo
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Re: 102 Feedback City

Post by Structo »

That is true on a lot of 12ax7's.

So why does HAD have his preamp tubes mostly connected with 6,7,8 as the first stage?
Tom

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talbany
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Re: 102 Feedback City

Post by talbany »

Yeah..Mullard says the same thing in there book about the lower noise floor on 678..I have done it both ways in several builds and personally can't hear any audible difference in a guitar amplifier..

Tony
" The psychics on my bench is the same as Dumble'"
surfsup
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Re: 102 Feedback City

Post by surfsup »

Interesting I wonder if the pinout leads internal to the tube do those runs. If so, it would have been better to have pin 9 as pin 9 and pins 1 and 8 as heaters instead of 4 and 5, and shift the PGK pins over on each side to keep each internal lead the shortest possible.

Is there a real explanation for this? I'm just guessing based on the drawing which shows pin 1 run across the center of the tube to reach the plate.
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Bob-I
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Re: 102 Feedback City

Post by Bob-I »

Structo wrote:That is true on a lot of 12ax7's.

So why does HAD have his preamp tubes mostly connected with 6,7,8 as the first stage?
Um... because that's the first triode :?
talbany
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Re: 102 Feedback City

Post by talbany »

Here is one more..Amp in the cab..Dlator in loop.. This time PAB is on..Standard Skyliner boost..
This time I used the cheapest guitar I had .. Washburn Delta King..I paid 100.00 for the guitar..
I had to stand about 6 ft from the amp with the hollow body..In this clip you can hear in spots the note flipping and harmonic differences a bit better with the hollow
Also here is a shot of the settings..Internal trimmer set @ 28K to ground..What do you think?

http://www.youtube.com/watch?v=eCywIFeMcyk

Tony
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" The psychics on my bench is the same as Dumble'"
Max
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Re: 102 Feedback City

Post by Max »

brentm wrote: http://youtu.be/Lwt9eKDxbbM - at 3:25 - and not nearly the bloom you hear from Tony's amp. But he holds a note with the drive up. Very slight harmonics toward the end of the note...Robben also flirts with the bloom in the intro "Peace on my Mind" (Truth, 2007).
Structo wrote:Here is Robben at Rockplast 2007. Peace on my Mind Check it out at 3:40 http://www.youtube.com/watch?v=a7OINxfKZW
Thank you guys!

So back again to Tony's question:
talbany wrote: Have all the original Dumbles you have played have this ability to run away…
Using these clips brentm and Tom recommended as examples, my impression is, that you’ll can make most- if not all - the original Dumble ODS amps I’ve played to respond like this - if you adjust their controls and your touch in an appropriate way and are familiar with their specific kind of character etc.. I still have doubts that this kind of response is caused by some "secret" special circuit detail that you find only in RF’s #102. Are you sure about this? And my impression is still, that what I hear in these clips seems to be a bit more controlled – at least in my personal perception. Or don’t you think so?

One more question to perhaps better understand what is discussed here:

Do you think that this kind of "feedback" and "bloom", as its called here, RF e.g. evokes in these clips recommended by brentm and Tom is something special that can only be achieved by a player – or perhaps at least far more easy or better etc. - when using a Dumble ODS, or even only by using RF’s #102? Or do you think that it could perhaps be achieved by using other equipement, too, like this one: http://www.youtube.com/watch?v=WQrP_0PQCDk

Or do you perceive this kind of interaction to be something completely different from what you hear in these RF clips recommended by brentm and Tom?

Thanks again and have a great time!

Max
talbany
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Re: 102 Feedback City

Post by talbany »

Max wrote:
brentm wrote: http://youtu.be/Lwt9eKDxbbM - at 3:25 - and not nearly the bloom you hear from Tony's amp. But he holds a note with the drive up. Very slight harmonics toward the end of the note...Robben also flirts with the bloom in the intro "Peace on my Mind" (Truth, 2007).
Structo wrote:Here is Robben at Rockplast 2007. Peace on my Mind Check it out at 3:40 http://www.youtube.com/watch?v=a7OINxfKZW
Thank you guys!

So back again to Tony's question:
talbany wrote: Have all the original Dumbles you have played have this ability to run away…
Using these clips brentm and Tom recommended as examples, my impression is, that you’ll can make most- if not all - the original Dumble ODS amps I’ve played to respond like this - if you adjust their controls and your touch in an appropriate way and are familiar with their specific kind of character etc.. I still have doubts that this kind of response is caused by some "secret" special circuit detail that you find only in RF’s #102. Are you sure about this? And my impression is still, that what I hear in these clips seems to be a bit more controlled – at least in my personal perception. Or don’t you think so?

One more question to perhaps better understand what is discussed here:

Do you think that this kind of "feedback" and "bloom", as its called here, RF e.g. evokes in these clips recommended by brentm and Tom is something special that can only be achieved by a player – or perhaps at least far more easy or better etc. - when using a Dumble ODS, or even only by using RF’s #102? Or do you think that it could perhaps be achieved by using other equipement, too, like this one: http://www.youtube.com/watch?v=WQrP_0PQCDk

Or do you perceive this kind of interaction to be something completely different from what you hear in these RF clips recommended by brentm and Tom?

Thanks again and have a great time!

Max
Max
Good questions..I will try to answer them the best I can through my personal experiences..

It would be difficult for me to do any accurate comparisons on my amp and the origional 102 without having it side by side under my hands..I have seen Robben on many occasions and although he doesn't use much feedback it seems as though it is always there, he just needs to call on it and it appears, all he needs to do is make the appropriate adjustments to his touch or pick attack or perhaps find the right position..Sometimes a simple turn gets the feedback going and let's the amp do the rest..
As Gil States here
I have always been fascinated by how some amps seem to want to feedback reglardless of anything (tubes, choice of particular components, etc.) and some just don't sound as lively.
There are some amps that are just a bit more sensitive to touch feedback and response than others..Perhaps this is why Robben has stuck with his 102 for so long!! My version just happends to be one of these livelier amps for whatever reason.. Perhaps I can find out why..
As far as control goes I am a big believer!!.. The clips I posted here also have my own technique for promoting such feedback and I did use them in my clips to show how the amp can take off when I ask it too.. If I do not want the feedback to appear I can simply alter my pick technique, position etc..Although this is obviously more difficult in PAB mode and with a hollow body guitar..I do know that if I spend more time on the amp I will make more accurate adjustments to better control all the dynamics of my 102 variant like Robben has obviously mastered his!!
Most Dumble amps I have heard do have this ability to when the player calls upon the amp to feedback it is there and is IMO part of what makes a Dumble a Dumble!!..If and when it happends does it respond like My amp or Robbens or Sonny's or Lowell George or Steve Ferris.. I really don't know..

I hope this answers your question!!

Tony
" The psychics on my bench is the same as Dumble'"
vibratoking
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Re: 102 Feedback City

Post by vibratoking »

Nothing about 102...

Just a quick note about the Rockpalast version of "Peace On My Mind" with the red ES 335. I heard or read, can't remember which right now, Robben's comments about that guitar. He said it was old wood. He is a big fan of old wood. He also said that guitar is unique in that it will start to feedback, but that the guitar has a characteristic of sqelching the feedback after it has started. I have never experienced a guitar like that, but you can hear it on the live recording.
ampdork
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Re: 102 Feedback City

Post by ampdork »

I wonder if Kimocks thoughts have any wisdom. He's spoken before that he plays his amps set before the threshold and his trip is PUSHING the amp where he wants it to go. He says Ford plays the opposite way, above the threshold and he "reigns" it in...
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...In fact as Kimock suggests I would say that Robben is doing more to control it then make it happen...
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talbany
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Re: 102 Feedback City

Post by talbany »

I know Robben at one time took the volume pots out of his Esquire.. Since he uses a volume pedal why have a 500k pot feeding a 500K pot
A player that goes through the trouble to get maximum signal transfer from his guitar to the front end sounds to me like someone looking to be on or over the edge!! :D
I imagine that big red 335 is prone to (as SRV would put it) get away from you and take you with 'em.

Tony :shock:
Last edited by talbany on Wed Mar 07, 2012 10:02 pm, edited 3 times in total.
" The psychics on my bench is the same as Dumble'"
brentm
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Re: 102 Feedback City

Post by brentm »

ampdork wrote:I wonder if Kimocks thoughts have any wisdom. He's spoken before that he plays his amps set before the threshold and his trip is PUSHING the amp where he wants it to go. He says Ford plays the opposite way, above the threshold and he "reigns" it in...
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...In fact as Kimock suggests I would say that Robben is doing more to control it then make it happen...
Or perhaps not so much as the amp, or key value changes on a D-style topology, but what side of the threshold you set your controls to, and how well you can use your guitar volume knob on the fly.. Or your touch and how you want the amp to react. Robben, al though one of the greatest players on the planet, is happy to sit back in the mix and play some percussive rhythm guitar. He always keeps some gas in the tank.... so that approach of having the amp on the verge of overdrive works well with his style.

Read Kimocks article on Dialing Up a Dumble if you haven't. He speaks to this in it, saying that you can hear the small voltage changes by rotating the pots and listening to the speaker blow.
This approach will let you know when the amp is "doing something". Regardless of tube type or guitar, etc... the amp can't hide from this kind of scrutiny, and it can't lie to you either, so do it, and center your efforts in those areas where a little voltage swing from your guitar will move the amp around a little.
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ayan
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Re: 102 Feedback City

Post by ayan »

I am the ultimate nitpicker... Robben's old EB volume pedals have 250K pots, if anything he should have changed the pot in the pedal. :) Sorry, that's my only contribution on this topic.

Other than to add that somehow Robben's main amp is, seemingly, a feedback machine according to those who have played it. Interestingly enough, his style has changed over the years to where long sustain does not seem to be a part of his vocabulary like it used to. He used all kinds of Fenders, Boogies, and the Yamaha combo and managed to make them all sing and sustain. He switched to the Dumble and also made it sustain like crazy with his 335s and Strats, until around the time he switched to the Esprit. Then, goodbye sustain. In TTYD he opted for a "high gain" tone - relatively speaking - and later for a fatter and flubbier (= Skyliner), albeit very musical, tone. Maybe Robben's amp should go to Santana. :)

Gil
talbany wrote:I know Robben at one time took the volume pots out of his Esquire.. Since he uses a volume pedal why have a 500k pot feeding a 500K pot
A player that goes through the trouble to get maximum signal transfer from his guitar to the front end sounds to me like someone looking to be on or over the edge!! :D
I imagine that big red 335 is prone to (as SRV would put it) get away from you and take you with 'em.

Tony :shock:
llemtt
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Re: 102 Feedback City

Post by llemtt »

talbany wrote:Hemtt/Martin
I thought that as well, so yesterday I put the amp in the cab and took it to VVT's Shop...

Tony
Tony, did you also played guitar in one room while the speaker was in another one?

this is a crucial test to understand if feedback happens at the "acoustical feedback path" or not

cheers
Teo
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jelle
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Re: 102 Feedback City

Post by jelle »

How about injecting a sine wave at OD2, then OD1, etc while monitoring if a signal comes up in the previous stages? That should be 10 minute test. :D

And it will tell you if there is significant crosstalk happening.
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