Don't get ideas now, it will turn into an F5 size sinks. I just wondered bcs all this time you did not say anything about 15mF caps. And by knowing your tendencies...
I connected the shields at one end, they are strapped to ground. R & L are carried by two of the three individual, jacketed wires. I have experienced no cross talk with this cable (at least not audible). If you follow the link posted above, it will show that this cable is specified for AV and other high bandwidth applications.
you have a problem.
You have not told us how the signal circuit maintains the flow and return of the signal.
It appears from your description that the right signal flows along the red wire. The left signal flows along the white wire. The third core is unused. The shield is connected (grounded) at one end only.
Where is the return route for the signal circuit?
It must be a circuit. The signal cannot flow unless you provide a return route.
I think you have told us that you hear music. If that is the case then there is a return route. Do you know where that route goes?
I suspect you never thought about it.
Hi Alon,
to verify your hum problem, i connected my pcb between my Tube-I-zator and my pre amp.
The Vin comes from the 15V line of my TDA1541A DAC-Shunt.
Absolute silence... So it is a problem in your setup.
An externally hosted image should be here but it was not working when we last tested it.
Hi Oliver,
Do you use just the Optivol? or do you use Optivol with the Dcb1? On a side note...i found using the salas shunt at 5v(deleting Optivol power supply section) to sound best...i also tried salas shunt at 8v into optivol power supply, but this was not as good.
Alon
I have just realised, that the hum changes with the volume...so hum gets louder when volume is turned up...and lower when turned down.
Oliver i noticed on the Optivol board there is a 7th hole next to the potentiometer...is this used for earthing the pot case?
Alon
Oliver i noticed on the Optivol board there is a 7th hole next to the potentiometer...is this used for earthing the pot case?
Alon
Im going to be using my own power supply (+-12v 1amp 3mv ripple shunt) that i built for my other parts of the amp.
Is there anything i need to change since i will be air wiring it?
Also on the output fets. If i dont care about dc off set (all my amps have 1 cap at either the driver or power stage), what are the benefits of having them current matched?
Is there anything i need to change since i will be air wiring it?
Also on the output fets. If i dont care about dc off set (all my amps have 1 cap at either the driver or power stage), what are the benefits of having them current matched?
Keep the inside ones of the 4 audio fets (the current sources) smaller IDSS than the outer ones. Don't know if it can have any other impact, never used widely apart fets there, it will surely give more DC offset. Nothing to change in the audio part if changing the reg types.
I know how to make a dc coupled balanced to unbalanced converter using a split supply with an opamp.
Is is possible with this buffer? I cant figure out where to put the negative signal. I could just use the positive signal, but id loose 3db of signal and all the nice noise rejection.
Is is possible with this buffer? I cant figure out where to put the negative signal. I could just use the positive signal, but id loose 3db of signal and all the nice noise rejection.
This is a single ended buffer. You would need 4 of those for 2ch if fully balanced in/out without chips producing a reverse.
I dont want fully balanced in/out. I want balanced in to unbalanced out. I dont think i can just pop the negative into the second fet.
PS: On second thought this might not work since the bottom fet is being used as a current source.
PS: On second thought this might not work since the bottom fet is being used as a current source.
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At the moment i couldn´t use the DCB1 because i am waiting to the Texas Components 220R & 220K.
I will also give the optivol a separate +5V Salas shunt and delete the onboard 7805 reg.
The 7th hole is only an additional fixing point. No conection to GND.
the B1 and the DCB1 are both unbalanced input to unbalanced output.
You have to convert the balanced plug to provide an unbalanced signal to feed into the unbalanced buffer.
The B1 & DCB1 are both single ended source follower (unity gain amplifier) that are loaded with a CCS (the lower jFET). They both have +IN and Signal Return. They don't have -IN.
If you want to preserve the noise cancellation of your balanced cable then look at the many other PASS designs that accept balanced input.
Why exactly isn't a 50K pot recommended, according to the wording in the BOM and this thread. Anything else but thermal noise? Channel tracking? I've got 1 ALPS Blue around here, which has nothing to do, so I guess I'll go with it, for now at least.
I havent looked over everything, but you want the pot to match the input impedance or lower then the input impedance. You dont want to drive a 25k amp with a 50k pot, but like i said i dont know what the input impedance is for this unit, i assume its huge.
