Lostcause said:
Thanks for the reply George, the LDR's don't like DC then?
No issues on the caps, I have some very nice polys
A little is ok, but I think you will have quite a bit on that buffer, even the 50k pot will be better of without it, as I detest the sound of caps in the signal path (even good ones).
I would prefer to see a buffer without dc blocking caps (even a good fet input opamp like the AD825 I think sounds better than a cap) Do you need the buffer, extra gain?
Cheers George
Do I need the buffer? Good question but I believe that this DAC rather high impedance and has 2.4VDC on the output anyway.
Trust me Sir, if I could do without the caps I would! but again, that T-amp has the same bias on it's inputs so I have to block it's path to ground somehow....
Maybe you geniuses (is that a word?) out there could come up with an alternative solution?...I would love to hear one that keeps it simple????
Trust me Sir, if I could do without the caps I would! but again, that T-amp has the same bias on it's inputs so I have to block it's path to ground somehow....
Maybe you geniuses (is that a word?) out there could come up with an alternative solution?...I would love to hear one that keeps it simple????
georgehifi said:
Let me rephrase that last comment about the opamp v cap sound they are both as bad as each other in my books, but in different ways, a good cap tends to soften and smear the sound a little to me, where the good opamp can be too etched and two dimensional, even the tubeiest! sounding opamp, I think the op275 then starts sounding like the cap.
Cheers George
Lostcause said:Do I need the buffer? Good question but I believe that this DAC rather high impedance and has 2.4VDC on the output anyway.
Trust me Sir, if I could do without the caps I would! but again, that T-amp has the same bias on it's inputs so I have to block it's path to ground somehow....
Maybe you geniuses (is that a word?) out there could come up with an alternative solution?...I would love to hear one that keeps it simple????
What dac gives 2.4v offset, give details about it's ouut stage.
Maybe I should put two caps in there with the lightspeed instead of the buffer? I'll give it a try...I have lots of good quality caps.
The change in impedance may make a big difference, you never know?
Edit: You got there first George...
It's a PS1 AKM DAC, you can see the name on the schematic. Let me see if I can obtain a shortcut to the PDF....There it is
DAC
The change in impedance may make a big difference, you never know?
Edit: You got there first George...
It's a PS1 AKM DAC, you can see the name on the schematic. Let me see if I can obtain a shortcut to the PDF....There it is
DAC
That's the whole point George...I have ripped it out!!
They were pretty poor anyway.....
It's just that I am trying...very hard!...to eradicate all things unnecessary from the signal path and the current setup does work well. You do get some slight noise when adjusting the volume but nothing too bothersome as I tend to listen at low levels anyway……That's also why I want to get the impedance matched properly…
Like you say Sir, why have parts in there you don't need?
They were pretty poor anyway.....
It's just that I am trying...very hard!...to eradicate all things unnecessary from the signal path and the current setup does work well. You do get some slight noise when adjusting the volume but nothing too bothersome as I tend to listen at low levels anyway……That's also why I want to get the impedance matched properly…
Like you say Sir, why have parts in there you don't need?
Lostcause said:That's the whole point George...I have ripped it out!!
They were pretty poor anyway.....
It's just that I am trying...very hard!...to eradicate all things unnecessary from the signal path and the current setup does work well. You do get some slight noise when adjusting the volume but nothing too bothersome as I tend to listen at low levels anyway……That's also why I want to get the impedance matched properly…
Like you say Sir, why have parts in there you don't need?
You really need to stop the dc offset from the source, otherwise you have a multiplicating effect all the way though with bigger uglier caps later on.
If this must be the way then I suggest.
AKM with good NX black gate on it's output, do'nt forget a say 300k resistor to ground after the cap.
Then the Lightspeed as I've made it.
Then your chip amp with Black gate NX on the input (omit the buffer).
Cheers George (going for a surf be back in a couple of hours)
This looks good to me Lee, the only question is the drive strength of the AKM, if it is good enough all will sound at it's best using this configuration.
Hopfully the AKM has a low enough output impedence to drive the load that it's now looking at, it's probaly half of what it saw before, if the inbuilt output opamps are of decent quality you will hear a much improved sound, if not everything will sound better except the bass will sound a little weak. Worth a dig.
Cheers George
Hopfully the AKM has a low enough output impedence to drive the load that it's now looking at, it's probaly half of what it saw before, if the inbuilt output opamps are of decent quality you will hear a much improved sound, if not everything will sound better except the bass will sound a little weak. Worth a dig.
Cheers George
To all the 33,000 odd members that have been looking at this thread, we are all obviously interested in passive pre's of some description, be they pots, switched resistors, transformers or the Lightspeed.
I believe we need a PASSIVE PREAMP forum of our own, not to be stuck here in the solid state (yuk) forum. To get our own PASSIVE PREAMP forum you should vote here.
http://www.diyaudio.com/request/
Under the Passive Preamp section that I have started with the first vote.
Please take the time to do this and get us out out limbo.
Cheers George
I believe we need a PASSIVE PREAMP forum of our own, not to be stuck here in the solid state (yuk) forum. To get our own PASSIVE PREAMP forum you should vote here.
http://www.diyaudio.com/request/
Under the Passive Preamp section that I have started with the first vote.
Please take the time to do this and get us out out limbo.
Cheers George
pinkmouse said:George, I'm not sure I'd really call the Lightspeed design "Passive" though, it does need electricity.
What controls the input signal attenuation and ouput signal feed is totaly passive, The active components have no electrical contact with any incomming or outgoing signal. So yes it is a passive attenuator. The fact that it operates with light does not make it active.
We are passive humans beings, if we stand in the sun does not suddenly make us active. Bit of Fung Shui? Duh?
Cheers George
planet10 said:
George has informed me that this comment has stopped people from voting for the idea. Don't stop.
The idea has been on this list since George 1st asked, but being on the list only means that the idea is under consideration, not that it will become reality. Your vote will push it up the list of potential changes.
dave
