Max
I see where you are confused.. I'll take a Mulligan here!!
The output impedance of the Dumblator can also be fairly low, so driving into the return (preamp in) of the amp, which presents a 220K load (the network we refer), you'll only lose a small (or smaller) amount of voltage
Sorry for the confusion!!
Tony
Should I use this with built in dlator?
Moderators: pompeiisneaks, Colossal
Re: Should I use this with built in dlator?
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
Tony,talbany wrote:The output impedance of the Dumblator can also be fairly low
I understand.
Thanks for the clarification and all the best,
Max
Re: Should I use this with built in dlator?
Max/Everyone
Let's see if I can explain this a bit better!!
.Phase inverters in these amps like to see a 1M load impedance/Loading capacitance to keep the tone and operating points consistent with the 1m master when you unplug the loop..
On to the Loop!
Even after you amplify the effects send signal through the return amp the source impedance still remains fairly low
80k plate impedance 100k plate load 250k pot total 430K source impedance sent to the PI.. Roughly less than 1/2 of what the PI want to see.
So why not just up the value of the 250k return pot.. It's obvious he wanted to shape the frequency response and insure the proper level from the return amp to keep from overdriving the PI
The 220k in the network then helps to raise the source impedance back up closer to what the PI wants to see..and there you have it one mans theory..
Really in the grand scheme of things it's not that big of a deal..If your amp sounds good without it leave it.. Just thought I would go a bit deeper and explain a little better about the load transfer..Besides the wifes gone and it's raining out and am bored..
Tony
Let's see if I can explain this a bit better!!
.Phase inverters in these amps like to see a 1M load impedance/Loading capacitance to keep the tone and operating points consistent with the 1m master when you unplug the loop..
On to the Loop!
Even after you amplify the effects send signal through the return amp the source impedance still remains fairly low
80k plate impedance 100k plate load 250k pot total 430K source impedance sent to the PI.. Roughly less than 1/2 of what the PI want to see.
So why not just up the value of the 250k return pot.. It's obvious he wanted to shape the frequency response and insure the proper level from the return amp to keep from overdriving the PI
The 220k in the network then helps to raise the source impedance back up closer to what the PI wants to see..and there you have it one mans theory..
Really in the grand scheme of things it's not that big of a deal..If your amp sounds good without it leave it.. Just thought I would go a bit deeper and explain a little better about the load transfer..Besides the wifes gone and it's raining out and am bored..
Tony
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
Tony, what are you talking about? The network is buffered by the Dumbleator. The PI doesn't see it. The PI sees the wiper of the return pot to ground (basically). Maybe 40K or so.
In a loopless amp, the PI sees the master's wiper to ground. Or most likely 200K or so.
In a loopless amp, the PI sees the master's wiper to ground. Or most likely 200K or so.
talbany wrote:Max/Everyone
Let's see if I can explain this a bit better!!
.Phase inverters in these amps like to see a 1M load impedance/Loading capacitance to keep the tone and operating points consistent with the 1m master when you unplug the loop..
On to the Loop!
Even after you amplify the effects send signal through the return amp the source impedance still remains fairly low
80k plate impedance 100k plate load 250k pot total 430K source impedance sent to the PI.. Roughly less than 1/2 of what the PI want to see.
So why not just up the value of the 250k return pot.. It's obvious he wanted to shape the frequency response and insure the proper level from the return amp to keep from overdriving the PI
The 220k in the network then helps to raise the source impedance back up closer to what the PI wants to see..and there you have it one mans theory..
Really in the grand scheme of things it's not that big of a deal..If your amp sounds good without it leave it.. Just thought I would go a bit deeper and explain a little better about the load transfer..Besides the wifes gone and it's raining out and am bored..
Tony
Re: Should I use this with built in dlator?
Scott
I think you have resistance confused with load..The load is indicated by the pot value which does not change (bottom grounded).. The resistance is where you have the pot set(wiper to ground) as you indicated... two different things..Used in this configuration..If you don't ground the bottom and use the top of the pot and wiper it now becomes a variable resistor and you lose the load and works as you describe.
A little info on no load pots for guitars.
http://www.projectguitar.com/tut/pots.htm
Tony
I think you have resistance confused with load..The load is indicated by the pot value which does not change (bottom grounded).. The resistance is where you have the pot set(wiper to ground) as you indicated... two different things..Used in this configuration..If you don't ground the bottom and use the top of the pot and wiper it now becomes a variable resistor and you lose the load and works as you describe.
A little info on no load pots for guitars.
http://www.projectguitar.com/tut/pots.htm
Tony
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
It depends on which direction you look from. The PI is connected to the wiper and looking backwards, the load is the resistance from ground... no?
Also, the 220K network is buffered by the dumbleator and is invisible to the PI. It has nothing to do with it.
Also, the 220K network is buffered by the dumbleator and is invisible to the PI. It has nothing to do with it.
talbany wrote:Scott
I think you have resistance confused with load..The load is indicated by the pot value which does not change (bottom grounded).. The resistance is where you have the pot set(wiper to ground) as you indicated... two different things..Used in this configuration..If you don't ground the bottom and use the top of the pot and wiper it now becomes a variable resistor and you lose the load and works as you describe.
A little info on no load pots for guitars.
http://www.projectguitar.com/tut/pots.htm
Tony
Re: Should I use this with built in dlator?
Scott
When I calculate the loading impedance going into a voltage divider or a pot (bottom grounded) I use the full load of the pot (This is just how I was taught and think) since you never really know where the resistance will be set (sorry should have mentioned this last post.. not thinking)....not to say that in an AC circuit in using a pot that the resistance doesn't change as you sweep it like you mention you have to assume in the calculations that someone might use the full load of the pot...So you can't really say the PI might see this or that..You are right not many here run the return wide open so yes it's not a 250K load there..
Tony
When I calculate the loading impedance going into a voltage divider or a pot (bottom grounded) I use the full load of the pot (This is just how I was taught and think) since you never really know where the resistance will be set (sorry should have mentioned this last post.. not thinking)....not to say that in an AC circuit in using a pot that the resistance doesn't change as you sweep it like you mention you have to assume in the calculations that someone might use the full load of the pot...So you can't really say the PI might see this or that..You are right not many here run the return wide open so yes it's not a 250K load there..
Looking at this from my chair the 250k pot and 220k network comes after the buffer and return amp before the PI so why wouldn't that effect the load on the PI..I am confused by this ... Help me..Also, the 220K network is buffered by the dumbleator and is invisible to the PI. It has nothing to do with it.
Tony
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
Tony, that would be the loading on the return amp. The PI is after the pot. It never sees the full pot value. Just the variable load to ground from the wiper. The return amp sees the constant 250k.
I was referring to 124s special network in my other comment. It comes before the dumbleator based on what I see. Therefore, it has no effect on PI loading at all. Look at the picture.
I was referring to 124s special network in my other comment. It comes before the dumbleator based on what I see. Therefore, it has no effect on PI loading at all. Look at the picture.
talbany wrote:Scott
When I calculate the loading impedance going into a voltage divider or a pot (bottom grounded) I use the full load of the pot (This is just how I was taught and think) since you never really know where the resistance will be set (sorry should have mentioned this last post.. not thinking)....not to say that in an AC circuit in using a pot that the resistance doesn't change as you sweep it like you mention you have to assume in the calculations that someone might use the full load of the pot...So you can't really say the PI might see this or that..You are right not many here run the return wide open so yes it's not a 250K load there..
Looking at this from my chair the 250k pot and 220k network comes after the buffer and return amp before the PI so why wouldn't that effect the load on the PI..I am confused by this ... Help me..Also, the 220K network is buffered by the dumbleator and is invisible to the PI. It has nothing to do with it.
Tony
Re: Should I use this with built in dlator?
AHHH!! I see it now.. I always thought it was on the return..Why would he put that there?...Thanks for the point out!!I was referring to 124s special network in my other comment. It comes before the dumbleator based on what I see. Therefore, it has no effect on PI loading at all. Look at the picture.
Tony
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
Anyone any idea?talbany wrote:Why would he put that there?...
Cheers,
Max
Re: Should I use this with built in dlator?
He put it on the tip shorting jack. Happens to be on the return. But, that is also where the master feeds to. So, with nothing plugged in, the signal is connected directly to the PI and bypasses the send. Plug in and the master signal goes through the network back to the send jack. Pretty cool.
Re: Should I use this with built in dlator?
Yeah..But why the network? Why not just short it?..Doesn't need the load.
Tony
Tony
" The psychics on my bench is the same as Dumble'"
Re: Should I use this with built in dlator?
Lets see #124 was built when, '83 or so? Don't know the history of the dlator, but maybe he did this before he started using bright switches on the dlator, then when the switches came along on the dlator he quit with this network. just a hypothesis.talbany wrote:Yeah..But why the network? Why not just short it?..Doesn't need the load.
Tony
Re: Should I use this with built in dlator?
Why do you feel the network has anything to do with loading? It is merely for frequency shaping. The loading at that stage, before the Dumbleator, is moot since it feeds the cathode follower.
talbany wrote:Yeah..But why the network? Why not just short it?..Doesn't need the load.
Tony
Re: Should I use this with built in dlator?
Why do you feel the network has anything to do with loading?
Scott
This was in reference to impedance loading..Since the buffer is low impedance you don't need to raise the the impedance there to get good voltage transfer..By my statement doesn't need a load..
Yes I know thanks for pointing it out..The loading at that stage, before the Dumbleator, is moot since it feeds the cathode follower.
Tony
" The psychics on my bench is the same as Dumble'"