Jens said:
Jens, how do u do this ? If you use the Aleph 1.7 pre-amp relay setup and drive it with BCD you get a linear steps unless you put a resistor across the ouput ala Rod Elliot for a 'fake' log, which is still -48db attenuation (for 8 bits as shown in the service manual)
We are talking about two different thinks here. Even I get “only” –48db attenuation in my AP1.7, simply I use Nelson’s relay set-up. Having said that, I use a completely different relay set-up in my Balanced Zen Line Stage, which allows for nearly –80db via voltage dividers!
Let’s assume the output impedance should be 5K (as happen in my BZLS), than the following resistor combinations for the voltage dividers are needed:
R1 R2
-40db = 4.990R and 51R (MSB)
-20db = 4.530R and 560R
-10db = 3.400R and 2.320R
-5db = 2.200R and 6.490R
-2.5db = 1.240R and 15.000R
-1.25db = 665R and 32.400R
-0.62db = 348R and 68.000R
-0.31db = 174R and 137.000R (LSB)
Example: Input---R1---Output---R2---GND
I hope this clarifies the situation, if not let me know… Jens
Let’s assume the output impedance should be 5K (as happen in my BZLS), than the following resistor combinations for the voltage dividers are needed:
R1 R2
-40db = 4.990R and 51R (MSB)
-20db = 4.530R and 560R
-10db = 3.400R and 2.320R
-5db = 2.200R and 6.490R
-2.5db = 1.240R and 15.000R
-1.25db = 665R and 32.400R
-0.62db = 348R and 68.000R
-0.31db = 174R and 137.000R (LSB)
Example: Input---R1---Output---R2---GND
I hope this clarifies the situation, if not let me know… Jens
Aha, I see, we were talking about difrent things !
With your dividers, I am assuming you have the -0.31b one first in the signal path and the -40db one last....
But what i don't understand is, if you had say -47.5db selected, then therefore the -40db, -5db and -2.5db attenuators are selected, won't the -40db and -5db attenuator affect the 'seen' impedence of the -2.5db attenuator? and cause accuracy problems
With your dividers, I am assuming you have the -0.31b one first in the signal path and the -40db one last....
But what i don't understand is, if you had say -47.5db selected, then therefore the -40db, -5db and -2.5db attenuators are selected, won't the -40db and -5db attenuator affect the 'seen' impedence of the -2.5db attenuator? and cause accuracy problems
I'm getting sort of disgusted with Eagle. I tried to open the file but get a load error 295 pop up. Anyone have any idea....This is the freebie version of the Eagle software that I'm using...perhaps thats the problem??? Nick, Could you post a picture of the pcb? If you can't look at a 4.01 version board with the 4.09 version software this thing is worthless.
On another note I finished the 8 bit comtrol by Jens and it works nicely. I had the relays hooked up in the wrong order at first but straightened that out quickly! I want to see more resolution out of this sort of digital control and I don't think it would be that hard to do....say like the 23 positions on the Aleph L preamp. Can one keep ganging together more 8 bit counters to do this? Sure, it would be alot of relays, but they are not that expensive, neither are the counters for that matter.
I think it would be far better quality than a switch type attenuator would be...even better that the DACT atenuators. Another thought...can one gang together several ADC chips, or bargraph chips to achieve this as well?
Mark
On another note I finished the 8 bit comtrol by Jens and it works nicely. I had the relays hooked up in the wrong order at first but straightened that out quickly! I want to see more resolution out of this sort of digital control and I don't think it would be that hard to do....say like the 23 positions on the Aleph L preamp. Can one keep ganging together more 8 bit counters to do this? Sure, it would be alot of relays, but they are not that expensive, neither are the counters for that matter.
I think it would be far better quality than a switch type attenuator would be...even better that the DACT atenuators. Another thought...can one gang together several ADC chips, or bargraph chips to achieve this as well?
Mark
Please help me out Mark...
How do i get a picture of the PCB. If i make a screendump you'll get a lot of useless extra.
I can send you a zipped file with all the contents for the design.
Gr,
Nick
How do i get a picture of the PCB. If i make a screendump you'll get a lot of useless extra.
I can send you a zipped file with all the contents for the design.
Gr,
Nick
Hi Nick,
That would be great...don't know why the download will not open up??? I'll let you know if it works ok this way.
cinerama84106@yahoo.com
Thanks,
Mark
That would be great...don't know why the download will not open up??? I'll let you know if it works ok this way.
cinerama84106@yahoo.com
Thanks,
Mark
solved
hope this will help
if anyone need eagle 4.01 i have it
here i made nice pdf files for you
hope this will help
if anyone need eagle 4.01 i have it
here i made nice pdf files for you
Yea, Looks good. Any idea why I can't open up the file on version 4.09r2?
Also does that pin out for connection to Jens control board equal a pin out of 1 to 1? If not whats the match up? Thanks!
Mark
Also does that pin out for connection to Jens control board equal a pin out of 1 to 1? If not whats the match up? Thanks!
Mark
i dont know that too
i have 3 eagle versions installed at this time 🙁 4.01 ,4.03 , 4.09r2 iam confused with it a little
at work we have 4.01 and (if it aint broke - dont fix it ) we do not plan to upgrade because this mess - it does not matter if it is freeware eagle or p*****d or registred it always behaves the same
i think protel is much better but not as that easy
i have 3 eagle versions installed at this time 🙁 4.01 ,4.03 , 4.09r2 iam confused with it a little
at work we have 4.01 and (if it aint broke - dont fix it ) we do not plan to upgrade because this mess - it does not matter if it is freeware eagle or p*****d or registred it always behaves the same
i think protel is much better but not as that easy
Thanx xsnailx... ( i must learn to do that too.. 😕 )
Mark, it's not the same volume control like Jens'. Jens uses other voltage dividers, though the control unit from Jens should be useable.
I'll be using it to. In the future i hope to use a remote, but that's not to easy for me to program
Grtz,
Nick
Mark, it's not the same volume control like Jens'. Jens uses other voltage dividers, though the control unit from Jens should be useable.
I'll be using it to. In the future i hope to use a remote, but that's not to easy for me to program
Grtz,
Nick
Electro-Nick,
just find ghostscript or adobe acrobat - full version not the reader they act like a printer so it is easy count on me for help
could you post an eagle schematic and control pcb too?
just find ghostscript or adobe acrobat - full version not the reader they act like a printer so it is easy count on me for help
could you post an eagle schematic and control pcb too?
xsnailx said:
The control unit will be the 8 bit control board from Jens. I think it was on page 3 or 4 from this thread.
The schematics shall i post at home. Don't want my boss to find out i'm diy'ing at work 😉
Grtz,
Nick
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