martin manning wrote: ↑Sat Jun 29, 2019 4:55 pm
Yes, and very well explained, too. I just thought I'd take the last step and diagram it.
Diagrams always help!
I have another thought about all of this. In Robben Ford's case, his sound was always bright when using the Dumbleator, and this has been explained by the 68 pF cap on the Master volume pot, the "tuned cables," etc. I think those are indeed factors, but in addition, RF always set his Dumbleator's SEND around 10 o'clock or so. Assuming that his has a 250 K pot, that means the output impedance of the SEND jack would probably be "low enough" to keep the highs. On the other hand, Larry Carlton's Dumbleator tone was always more compressed. For a while he even had the Audio Arts EQ in the rack to "add mids and highs" -- his own words in the first Star Licks video when showing his gear. His Dumbleator SEND setting was high, like 1 o' clock or so, probably a 20 - 30% taper pot, so he likely lost quite a bit of highs that way. The story about Larry's Dumbleator, according to Brandon, was that Larry threw it in the trash because he hated it -- "it changed the sound too much," he reportedly told Brandon. So be it. However, now Larry is using Brandon's D-lator clone, just saw him a couple of weeks ago, but the SEND control on that is set pretty low. Maybe LC was a little too hasty dumping his Dumbleator? Another factoid: LC's old Dumbleator did not have bright switches.
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Last edited by ayan on Sat Jun 29, 2019 5:38 pm, edited 3 times in total.
Gil
Here is the Series/Parallel mod I use. It takes is a 500k Dual gang pot (stereo pot) wired in antiphase plus a couple of 10k mix resistors. The best pot would be an anti-log, but a regular linear stereo 500k pot will do. This ensures a smooth transition from wet/dry mix ratios and helps prevent any null spots a normal mono pot might have. Since the two 500k sections are wired in parallel. the recovery input will still "see" 250k ( like the original Dumblelator). The 10k series resistors prevent the signal sources from being directly shorted to ground at any setting. And doesnt add to or detract from the sound.
When the loop's send and return jacks are not in use, the switching jack ensures that the dry signal is applied to both potentiometers simultaneously, so the signal level reaching the recovery stage is constant regardless of the setting of the mix control.
If you want to try this mod on an outboard "two knob" dumblelator, and you dont want to drill new holes, you might consider substituting the "Send pot" for a couple of resistors and putting the mix control in the "send pot" hole on the faceplate. On my Dumblelator I always leave the send pot at 11 o'clock anyway. "The return" knob will still act as master control.
This should give you a buffered send out to the pedals however you may want to add another buffer back up-stream after the effects if you want to preserve signal integrity back through the return for runs over 6ft.
BTW.I have not used this for runs over 6ft yet but I don't see why it would'nt work well for you with a little tweaking.
I generally get best results running my effects pretty wet. YMMV
Serparallel.jpg
Tony
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" The psychics on my bench is the same as Dumble'"
Gil
My D-Lator has 2-35 (35%) 250k pots and apart from running the "input" volume at around noon. These settings tell me the settings in this pic is real close to how I set mine (@gig volume) 35% between 9/10 oclock on both
Larry Carlton June 13 2019 (1) - Copy (1).JPG
Tony
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Last edited by talbany on Sat Jun 29, 2019 5:54 pm, edited 3 times in total.
" The psychics on my bench is the same as Dumble'"
Thinking about this, a 25k pot or a 15 k pot would solve the problem for impedance losses on a acceptable, non audible level. Isnt it a bit silly to use a buffer when the actual cathode follower is buffer?(no offense!).
How hard can it be.
First thing when the weathers cooled down here in the Netherlands: Im gonna change the send pot on one of my dumblelators. I'll let you know!
martin manning wrote: ↑Sat Jun 29, 2019 4:45 pm
Marcus you would have to arrange your cables and buffers like this to reduce cable losses.
that's exactly how I have it Martin.
As I said it's all in a breakout box under the pedal board.
M
Marcus, I think we're talking past each other here. If the buffer is under the pedalboard, the cable run from the Dumbleator SEND to the board buffer will lose highs. In Martin's diagram, the buffer is located right next to the Dumbleator SEND, such that the long cable run from there to the pedalboard is buffered.
erwin_ve wrote: ↑Sat Jun 29, 2019 5:50 pm
Gil thanks for your response on the impedance.
Thinking about this, a 25k pot or a 15 k pot would solve the problem for impedance losses on a acceptable, non audible level. Isnt it a bit silly to use a buffer when the actual cathode follower is buffer?(no offense!).
How hard can it be.
First thing when the weathers cooled down here in the Netherlands: Im gonna change the send pot on one of my dumblelators. I'll let you know!
Unless you have real short cables from the SEND jack to the FX, the sound will be brighter, guaranteed. I said that didn't have the right pots lying around, but I had some 10 KA pots that I guess I had bought a lifetime ago for whatever the reason. They measured low, around 8K or so, and the bushing was not long enough to fit in the Dumbleator with a lock washer on the inside and a flat one on the outside. So, while this particular pot was not going to be a keeper, I still tried it. With it, the amp was about as bright as when I had set the 250K pot all the way up. I thought this would turn into another rabbit hole for me... If 8K was too bright, I should be prepared to also try a proper 10K, a 25K, a 50K and maybe even a 100K. I weighed my options and I chose to post here instead to see if anyone else had toyed with this before, or maybe to recruit some volunteers. Sounds like I may have found one, Erwin. Really though, I played a gig last weekend keeping the SEND pot dialed down and things worked really well. In fact, I listened to a recording of it and things sounded a little brighter than I would have preferred, so next time I will try with the SEND pot dialed a little higher. And at some point I will probably buy and try other pot values.
martin manning wrote: ↑Sat Jun 29, 2019 4:45 pm
Marcus you would have to arrange your cables and buffers like this to reduce cable losses.
that's exactly how I have it Martin.
As I said it's all in a breakout box under the pedal board.
M
Marcus, I think we're talking past each other here. If the buffer is under the pedalboard, the cable run from the Dumbleator SEND to the board buffer will lose highs. In Martin's diagram, the buffer is located right next to the Dumbleator SEND, such that the long cable run from there to the pedalboard is buffered.
Gil,
Yes, I miss understood that too so Im at cross purposes a bit In my mind I was 'thinking' that the send from the Dumbleator was by it's nature 'buffered' so I thought that's what Martin's plan was and that would then be how that rig was set up.
Delving into this now I see where your coming from but I always thought the whole point of the dumbleator Cathode follower was to provide a buffered signal.
Why did Dumble couple a CF buffer with a high value pot? I'd love to hear him share that with us.
I would think it would be frequency response. Right?.Since a pot is a voltage divider As you lower the value of the pot you lose low-end frequency response and gain. At some point and as you go lower the loop will start to sound flat ,stiff and anemic. So it's a trade-off.
Tony
" The psychics on my bench is the same as Dumble'"
Why did Dumble couple a CF buffer with a high value pot? I'd love to hear him share that with us.
I would think it would be frequency response and gain. Right?.Since a pot is a voltage divider As you lower the value of the pot you lose low-end frequency response and gain. At some point and as you go lower the loop will start to sound flat ,stiff and anemic. So it's a trade-off.
Tony
Probably not gain, I would suspect. The 12AX7 CF Zout is 600 Ohms, so one could easily use a 50K pot and not lose anything. In addition, the whole purpose of the Dumbleator is not only to lower the impedance of the signal at the preamp out, but also to pad it down since it's way too hot for even line level FX. Now, frequency response, probably. But, Dumble could have used a larger coupling cap out of the CF along with a lower value pot to keep the frequency response broad, while keeping the output impedance low. I'll try to give HAD a call and ask him about it.
Yeah! But you know how these things go? some things that you think might look OK on paper until you get in there and change them might make a difference
So now you got me thinkin I have my old test lator sitting out here and a ton of pots. I'll be the monkey. What values do you want me to try? (I'll do 3)
BTW.If there is 1 thing I've learned from HAD is? There is always a method behind the madness
Tony
" The psychics on my bench is the same as Dumble'"
talbany wrote: ↑Sun Jun 30, 2019 1:14 am
Yeah! But you know how these things go? some things that you think might look OK on paper until you get in there and change them might make a difference
So now you got me thinkin I have my old test lator sitting out here and a ton of pots. I'll be the monkey. What values do you want me to try? (I'll do 3)
BTW.If there is 1 thing I've learned from HAD is? There is always a method behind the madness
Tony
Tony, agreed, HAD's mom didn't raise no dummy. Since you've volunteered, I'll make a request: 10K, 25K and 50K. BTW, the coupling cap is 0.47uF, right? I guess 25K should be a good choice. Thanks in advance!
talbany wrote: ↑Sun Jun 30, 2019 1:14 am
Yeah! But you know how these things go? some things that you think might look OK on paper until you get in there and change them might make a difference
So now you got me thinkin I have my old test lator sitting out here and a ton of pots. I'll be the monkey. What values do you want me to try? (I'll do 3)
BTW.If there is 1 thing I've learned from HAD is? There is always a method behind the madness
Tony
Tony, agreed, HAD's mom didn't raise no dummy. Since you've volunteered, I'll make a request: 10K, 25K and 50K. BTW, the coupling cap is 0.47uF, right? I guess 25K should be a good choice. Thanks in advance!
G.
Yep .47! I am pretty sure that lator is all stock. I'll double check before I start. Will go 50k and work down. If it's real obvious I'll make some clips
T
" The psychics on my bench is the same as Dumble'"
Really though, I played a gig last weekend keeping the SEND pot dialed down and things worked really well. In fact, I listened to a recording of it and things sounded a little brighter than I would have preferred, so next time I will try with the SEND pot dialed a little higher. And at some point I will probably buy and try other pot values.