My first Dumble finally started
Moderators: pompeiisneaks, Colossal
My first Dumble finally started
This if my first time using a board, so it's pretty exciting. I'm attaching a photo of the board, with a few parts in place. Looks pretty ok I think..let's hope it'll sound even better
By the way. I read some place that big cathode caps give a bassy sound, while small give a more mid rangy sound, while in between, say around 4-8 uF, gives a more "fusion" sound... Does this make sense?
Tommy
By the way. I read some place that big cathode caps give a bassy sound, while small give a more mid rangy sound, while in between, say around 4-8 uF, gives a more "fusion" sound... Does this make sense?
Tommy
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Re: My first Dumble finally started
Looks good Tommy.....
Trust me on this.... Try and find milspec metal films for the plates. It does matter and is noticeable..... As far as I know, Dumble never ever used carbon on the plates.
Do it right as you will be investing a lot of time in the project.
It is easy to change bypass caps or add a switch to toggle CL2 between 1, 5, and 10uf. I find this very useful and the difference between 5 and 10 is much more noticeable than you would think!!
Trust me on this.... Try and find milspec metal films for the plates. It does matter and is noticeable..... As far as I know, Dumble never ever used carbon on the plates.
Do it right as you will be investing a lot of time in the project.
It is easy to change bypass caps or add a switch to toggle CL2 between 1, 5, and 10uf. I find this very useful and the difference between 5 and 10 is much more noticeable than you would think!!
Re: My first Dumble finally started
Ok.. high watt too, or just normal wattage metal film mil spec?
Any recommendations?
Tommy
Any recommendations?
Tommy
Re: My first Dumble finally started
Vishay Dale RN65
Mouser has them. 1/2 watt rated but probably more like 1 watt.
Funkalicious Groove, Normster, Bob I, Pedro, etc... have all tried them and agree!!!
Mouser has them. 1/2 watt rated but probably more like 1 watt.
Funkalicious Groove, Normster, Bob I, Pedro, etc... have all tried them and agree!!!
Tdale wrote:Ok.. high watt too, or just normal wattage metal film mil spec?
Any recommendations?
Tommy
Re: My first Dumble finally started
Thanks! This forum is GOLD!!!
I made a Matchless DC30 clone, using only Riken ohm carbon film resistors all through, except in the power supply. I wonder what would happen if I got some metal films for the plates.
How exactely does the metal films affect the sound?
Tommy
I made a Matchless DC30 clone, using only Riken ohm carbon film resistors all through, except in the power supply. I wonder what would happen if I got some metal films for the plates.
How exactely does the metal films affect the sound?
Tommy
Re: My first Dumble finally started
I used Riken Ohm in my clone but swapped to the RN65 and prefer the metal films..... They have a certain "ting" on top. Not sure they would work well in other amps. Something about the topography of the Dumble seems to make them a great match!
Plus they are cheap
Btw, try using 160k-180k to feed the 100k pre-OD trimmer. I like the dynamic sound more than a 220k.
Also, I like the Skyliner stack. .01 midcap, 250ka mid pot, .001uf across a 500ka bass pot. Here is another tip if you are using midboost. Dumble used a .002 PS Orange drop and a 390pf in series. Not a .0022uf I know it is a minor point, but I like the sound of the net treble cap around 315pf to 320pf. WIth a .0022uf you are over 330pf. Every little bit of blueprinting and love counts IMO.
Plus they are cheap
Btw, try using 160k-180k to feed the 100k pre-OD trimmer. I like the dynamic sound more than a 220k.
Also, I like the Skyliner stack. .01 midcap, 250ka mid pot, .001uf across a 500ka bass pot. Here is another tip if you are using midboost. Dumble used a .002 PS Orange drop and a 390pf in series. Not a .0022uf I know it is a minor point, but I like the sound of the net treble cap around 315pf to 320pf. WIth a .0022uf you are over 330pf. Every little bit of blueprinting and love counts IMO.
Re: My first Dumble finally started
I was planning to use the other od entrance... with a bridge resistor, and two resistors from each end, through a trim pot and then to ground..
But I hear lots of good things about the 220K into a 100K trim... or as you say, 160-180 into the trim..
The good thing with using a board in stead of point to point, is that it's pretty easy to make changes...
Tommy
But I hear lots of good things about the 220K into a 100K trim... or as you say, 160-180 into the trim..
The good thing with using a board in stead of point to point, is that it's pretty easy to make changes...
Tommy
Re: My first Dumble finally started
I can't stress enough to NOT use that wierd network. It is not in any "grail" era amp I ever heard of. The only reason people even try it is because a couple of early ungooped Dumbles had it. He moved on.... Don't waste your time.
Tdale wrote:I was planning to use the other od entrance... with a bridge resistor, and two resistors from each end, through a trim pot and then to ground..
But I hear lots of good things about the 220K into a 100K trim... or as you say, 160-180 into the trim..
The good thing with using a board in stead of point to point, is that it's pretty easy to make changes...
Tommy
Re: My first Dumble finally started
That's noted
Tommy
Tommy
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Re: My first Dumble finally started
Dogears is right.
Metal films do good to lower the noise floor and there's a sparkle when u use them. The higher the wattage rating the better. If you have a choice between 1 watt and 0.5 watt, take the 1 watt - lesser noise.
Regarding the network to the OD, 220k works (or 150k) into 68K is much simpler to wire and u get good immediate results ....
Cheers.
Happy cloning ...
Metal films do good to lower the noise floor and there's a sparkle when u use them. The higher the wattage rating the better. If you have a choice between 1 watt and 0.5 watt, take the 1 watt - lesser noise.
Regarding the network to the OD, 220k works (or 150k) into 68K is much simpler to wire and u get good immediate results ....
Cheers.
Happy cloning ...
Re: My first Dumble finally started
And not use the trim you mean? Is there any resistor to ground in the way you explained?
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Re: My first Dumble finally started
Oops, I meant with the trimmer ...
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Re: My first Dumble finally started
If the metal resistors are the one to use then what about capacitors.
Would you only use Sprages 716 series ?
Ans for electrolytic capacitor use the blue Sprages also ?
Would you only use Sprages 716 series ?
Ans for electrolytic capacitor use the blue Sprages also ?
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Re: My first Dumble finally started
How's the Dumble amp coming along? Do you have a good schematic available and a parts list?
Many thanks.
Ellis
Many thanks.
Ellis
Ellis