I plan to build a Dumbleator to complement my 100W ODS, but after reading the discussions, the two design approaches, and the builders who have experienced their results, what's the winner here? The versatility of the series/parallel, has it's points, but don't want to sacrifice tone for versatility.
Regardless of the approach, my power section will use a full bridge w/ a Fender Reverb transformer, and not the HAD voltage doubler ckt. Having a spare P-TF47609 transformer in my shop is pushing the pwr supply approach. Any suggestions is appreciated.
Dumbleator Series/Parallel or Standard, Pros/Cons?
Moderators: pompeiisneaks, Colossal
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
Bob
Much of my decision has to do the quality of the effect unit I use.. If you have good unit with a nice sounding analog preamp I prefer series loop .. Not so good sounding units work better in parallel naturally.. I know you and everyone here knows this thought I would throw in a reminder on the fridge...Good Luck with the build..
Tony
Much of my decision has to do the quality of the effect unit I use.. If you have good unit with a nice sounding analog preamp I prefer series loop .. Not so good sounding units work better in parallel naturally.. I know you and everyone here knows this thought I would throw in a reminder on the fridge...Good Luck with the build..
Tony
" The psychics on my bench is the same as Dumble'"
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
Thanks Tony, the reason I asked is the HAD design puts the .22/20M snubber at the return wiper. The serial/parallel layout places it at the grid, in addition to a .47uF in series w/ the 200k/500pF.
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
I think the way the parallel loop is configured is because Claus, who drew the parallel loop, is trying to preserve the functionality of the series in addition to the parallel loop.
Also, I don't believe the Return (output) pot is original to the design.
Normally that is a fixed 220K resistor.
I tried an earlier version of the parallel loop but it didn't work too great for me, most likely due to the pedals I was using in it.
But that version did not have those extra caps and grid leak resistors.
On my series loop I did install a bypass switch on back which works well so you can check to see if the amp is balanced with and without the loop.
Also, I don't believe the Return (output) pot is original to the design.
Normally that is a fixed 220K resistor.
I tried an earlier version of the parallel loop but it didn't work too great for me, most likely due to the pedals I was using in it.
But that version did not have those extra caps and grid leak resistors.
On my series loop I did install a bypass switch on back which works well so you can check to see if the amp is balanced with and without the loop.
Tom
Don't let that smoke out!
Don't let that smoke out!
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guitarjazz
- Posts: 35
- Joined: Fri Aug 24, 2007 7:36 pm
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
The one Dumbleator I ever fooled with had these bright switches that did very little. I wonder why they were put there in the first place.
I really love the parallel loops in my Mesa Subway Rocket. I've been looking at the Lehle parallel loop box.
I really love the parallel loops in my Mesa Subway Rocket. I've been looking at the Lehle parallel loop box.
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
The bright switches are there to counter long cable runs to and from the loop.
Although I didn't care for the .001uF cap on the Send or Drive pot.
Way too much, so I changed that to a 500pf.
I was trying out a new cable yesterday and it completely killed my tone.
So you must use high quality, low pf cable if you are running 10 ft or more to and from the pedal board.
The bright caps like any bright cap on a volume pot or control will do less and less as the pot is turned up and is really only useful at below 12:00 on the dial.
Although I didn't care for the .001uF cap on the Send or Drive pot.
Way too much, so I changed that to a 500pf.
I was trying out a new cable yesterday and it completely killed my tone.
So you must use high quality, low pf cable if you are running 10 ft or more to and from the pedal board.
The bright caps like any bright cap on a volume pot or control will do less and less as the pot is turned up and is really only useful at below 12:00 on the dial.
Tom
Don't let that smoke out!
Don't let that smoke out!
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guitarjazz
- Posts: 35
- Joined: Fri Aug 24, 2007 7:36 pm
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
That's interesting. This one had a HAD coax 1/4-1/4 cable...very stiff.
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guitarjazz
- Posts: 35
- Joined: Fri Aug 24, 2007 7:36 pm
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
Your picture cracks me up in sort of sober way. One of my sons was experimenting with circuits( little Radio Shack kit) when he was about 5 or 6. I was in the room with him but not watching his every move. All of a sudden I saw a bright flash. He had inserted both ends of the circuit into the wall and the little flashlight bulb in his circuit probably saved his life. Whew! Maybe he's destined to be an amp builder??
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
Yeah, I get a lot those kinds of comments about it.
The kid in that shot looks enough like me when I was that age that it could very well be me.
But my little brother was the one that liked to chew on live extension cords when he was young and poke things into the receptacles.
I think he got shocked at least once but he wasn't seriously hurt.
He used to try and stick things into the wall plug too but we tried to keep up with him and kept all the paper clips and such away from him.......
I was very surprised about that shielded cable being so high in capacitance.
I measured the cable that was giving me grief, it is 15 ft long.
Probably not the most scientific method but I measured the capacitance with my DVM and it was 1500pf!
So that means for the send and return I had about 3000pf in cable!
When I was using that cable it sounded like somebody threw a wet blanket over my amp and speaker cab.
I didn't make the correlation between that cable and the tone until after trying several tricks to brighten up the tone.
It was a forehead slapping moment when I tried my other cable and the tone came back. [IMG:25:29]http://i23.photobucket.com/albums/b392/ ... /thwap.gif[/img]
I think I have read before that the cable used in a loop is not that important tone wise, but I am here to say BS, it killed the tone.
The other two that I use are about 10-12 ft and they are around 500pf.
So two of those was 2/3 less capacitance than the bad ones.
The kid in that shot looks enough like me when I was that age that it could very well be me.
But my little brother was the one that liked to chew on live extension cords when he was young and poke things into the receptacles.
I think he got shocked at least once but he wasn't seriously hurt.
He used to try and stick things into the wall plug too but we tried to keep up with him and kept all the paper clips and such away from him.......
I was very surprised about that shielded cable being so high in capacitance.
I measured the cable that was giving me grief, it is 15 ft long.
Probably not the most scientific method but I measured the capacitance with my DVM and it was 1500pf!
So that means for the send and return I had about 3000pf in cable!
When I was using that cable it sounded like somebody threw a wet blanket over my amp and speaker cab.
I didn't make the correlation between that cable and the tone until after trying several tricks to brighten up the tone.
It was a forehead slapping moment when I tried my other cable and the tone came back. [IMG:25:29]http://i23.photobucket.com/albums/b392/ ... /thwap.gif[/img]
I think I have read before that the cable used in a loop is not that important tone wise, but I am here to say BS, it killed the tone.
The other two that I use are about 10-12 ft and they are around 500pf.
So two of those was 2/3 less capacitance than the bad ones.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
OK back on topic.
Tom have you tried both circuits? If so, are you happy with the tone in each mode?
thanks
Tom have you tried both circuits? If so, are you happy with the tone in each mode?
thanks
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
Bob, I tried an earlier version of the parallel.
It was such that with a few easy wiring changes and an additional 500pf/ 220K for the parallel loop.
It did not allow for switching between series and parallel.
I didn't care for it and it was probably mostly due to the pedals I was using which are a EHX Stereo Memory Man and Boss RV-5 reverb.
It did not mix very good the wet and dry sides.
That was several versions of the series/ parallel schematic ago.
If I were to do it again I would probably build a new tube board.
I also think it would work better with line level effects. Not sure why my setup didn't work but I suspect impedance mismatches were the problem.
However, I did install the bypass switch on my serial loop, that is a nice feature to see if you are at unity with the loop and without.
It was such that with a few easy wiring changes and an additional 500pf/ 220K for the parallel loop.
It did not allow for switching between series and parallel.
I didn't care for it and it was probably mostly due to the pedals I was using which are a EHX Stereo Memory Man and Boss RV-5 reverb.
It did not mix very good the wet and dry sides.
That was several versions of the series/ parallel schematic ago.
If I were to do it again I would probably build a new tube board.
I also think it would work better with line level effects. Not sure why my setup didn't work but I suspect impedance mismatches were the problem.
However, I did install the bypass switch on my serial loop, that is a nice feature to see if you are at unity with the loop and without.
Tom
Don't let that smoke out!
Don't let that smoke out!
switching
Tom, when you say did not allow for switching... are you saying that the mismatch in levels between the parallel and series mode required additional tweaks so that you could not fluidly switch between the two modes.
ange
ange
Re: Dumbleator Series/Parallel or Standard, Pros/Cons?
No Ange,
I just didn't do a full conversion when I tried it. It was only parallel the way i had it wired.
It lasted all of about 5 minutes before I reverted back to a regular loop.
I'm not even sure if I want a parallel loop because since both my delay and reverb have wet/dry pots, I just adjust how much I want of the effect in my sound.
It may be slightly cleaner sounding if you go with a wet/dry rig but when in parallel mode, the Return pot acts as the wet/dry blend so it is the same thing essentially.
Maybe one day I will buy a professionally built amp and loop.
I just didn't do a full conversion when I tried it. It was only parallel the way i had it wired.
It lasted all of about 5 minutes before I reverted back to a regular loop.
I'm not even sure if I want a parallel loop because since both my delay and reverb have wet/dry pots, I just adjust how much I want of the effect in my sound.
It may be slightly cleaner sounding if you go with a wet/dry rig but when in parallel mode, the Return pot acts as the wet/dry blend so it is the same thing essentially.
Maybe one day I will buy a professionally built amp and loop.
Tom
Don't let that smoke out!
Don't let that smoke out!