Very good observation. You're right, a MasterIII rack indeed.
I'm a Radar and RF guy, that is right. I got also a good formation in industrial control and sensor/data collection. I also do electric work and installation work.
Bye...
I'm a Radar and RF guy, that is right. I got also a good formation in industrial control and sensor/data collection. I also do electric work and installation work.
Bye...
Peter Daniel said:
Peter,
I've been meaning to ask you if you use your passive I/V DAC with this preamp and passive attenuator when you compare them.
The TVC wants to see low output impedance from the source, something a passive I/V DAC does not have. My TVC (actually an autoformer) has even lower impedance than your S&B TVC and is extremely demanding of the source.
I know there is only so much time in the day to try things, but I wonder if you'd be happiest with some sort of simple, but carefully conceived buffer following your DAC before it feeds the TVC.
Jeff
I'm using passive output on my DAC.
By passive attenuator, I didn't mean TVC stage (as I still didn't compare it against active preamp). I was only talking about potentiometer or resistor switcher (which although good, are not as good as TVC, depending on setup, of course).
I tried DAC buffering, but to me, the resistors sounds "purer". I also think that the role of active preamp stage was greatly overlooked in recent times, as everybody thought that "passive" should be better.
My recent experiments show that the sound possible with active stage is somewhat surprising and I didn't know that so much information and this way of presentation was possible. I'm talking here mostly about sound gradation, texture, rhythm and space between notes. It just seems that the overall presentation is more liquid and richer in tonality. At the moment, I like it a lot.
The ML preamp was already modified substantially, but not completely yet. Comparing to what it was originally (38S version) to what it sounds now, is like comparing old Pioneer receiver to modern day GC😉
By passive attenuator, I didn't mean TVC stage (as I still didn't compare it against active preamp). I was only talking about potentiometer or resistor switcher (which although good, are not as good as TVC, depending on setup, of course).
I tried DAC buffering, but to me, the resistors sounds "purer". I also think that the role of active preamp stage was greatly overlooked in recent times, as everybody thought that "passive" should be better.
My recent experiments show that the sound possible with active stage is somewhat surprising and I didn't know that so much information and this way of presentation was possible. I'm talking here mostly about sound gradation, texture, rhythm and space between notes. It just seems that the overall presentation is more liquid and richer in tonality. At the moment, I like it a lot.
The ML preamp was already modified substantially, but not completely yet. Comparing to what it was originally (38S version) to what it sounds now, is like comparing old Pioneer receiver to modern day GC😉
Peter Daniel said:
I don't mean to suggest using active I/V for the DAC. Keep the passive I/V DAC and add an active stage (you could duplicate a stage from the ML pre, for example) following it so the output impedance is kept low for the TVC.
My TVC sounds fantastic or terrible depending on the source. I'm suggesting that perhaps you've not gotten the best from your TVC. With a buffer between it and the DAC, it may perform better.
OTOH, maybe I need to hear a good preamp. The $1000 (and S'pile recommended) preamp I used when I compared it to the TVC was so vastly inferior that I thought all preamps must be evil.
It is in great part an issue of matching as well. I plan to use the preamp very close to the DAC and the amps some 15 feet away. Having balanced outputs on preamp allows me to run balance interconnects and place the amps very close to the speakers.
I also enjoy some features on the preamp (like 0.1 dB steps for volume, remotely adjusted balance and polarity switch)
I also enjoy some features on the preamp (like 0.1 dB steps for volume, remotely adjusted balance and polarity switch)
New perfect solution to add headphone jack to the ML38 preamp, see http://www.diyaudio.com/forums/showthread.php?s=&threadid=36454
One of the upgrades to bring 380 status to this preamp is the change of I/V conertor chip. Originally OPA2604 was used and upgraded version use AD823. Madrigal claims that new chip is 12 times faster and has 6 times less current noise. They also add that the combination of speed and lower noise in this part is critically important, and a huge step forward in available technology.
This should translate in improved dynamics and improved manifestations: quiet spaces between notes are quieter, vocals are more full bodied and real, and the overall sense of realism is enhanced.
Well, after reading that I decided to replace the part and I had AD823 in my preamp. I also lowered the 4 surrounding resistors to 100ohm (as recommended).
Right from the start I knew it does not sound right. The vocals seemed indeed to have more presence, but also they were brighter, almost annoying) and the impression of space, acoustic was gone. Overall presentation seemed rather flat and artificial. I returned back to 1K resistors, and this improved things, but still nbot the point that it was even comparable what it sounded like with OPA2604. It just wasn't real enough, always leaving impression that one is listening to recorded music without anything that draws your attention. The magic was not there.
Today I placed OPA2604 back and things are good again: the 'magic' is back.
This makes me wonder if it makes any sence to replace other ICs. I already had dubts when I replaced input switch (BG411). I also thought that a previous part sounded better.
So my recommendation is use sockets and give your self a chance to listen to both chips, I installe dmine permamnently and had hard time with removing them back and forward.
I'm also interested if anybody else can confirm or have similar finding?
This should translate in improved dynamics and improved manifestations: quiet spaces between notes are quieter, vocals are more full bodied and real, and the overall sense of realism is enhanced.
Well, after reading that I decided to replace the part and I had AD823 in my preamp. I also lowered the 4 surrounding resistors to 100ohm (as recommended).
Right from the start I knew it does not sound right. The vocals seemed indeed to have more presence, but also they were brighter, almost annoying) and the impression of space, acoustic was gone. Overall presentation seemed rather flat and artificial. I returned back to 1K resistors, and this improved things, but still nbot the point that it was even comparable what it sounded like with OPA2604. It just wasn't real enough, always leaving impression that one is listening to recorded music without anything that draws your attention. The magic was not there.
Today I placed OPA2604 back and things are good again: the 'magic' is back.
This makes me wonder if it makes any sence to replace other ICs. I already had dubts when I replaced input switch (BG411). I also thought that a previous part sounded better.
So my recommendation is use sockets and give your self a chance to listen to both chips, I installe dmine permamnently and had hard time with removing them back and forward.
I'm also interested if anybody else can confirm or have similar finding?
I will try it as well I just need to pick up these 100ohm resistors and I have sockets already in place. I was wondering why they were there 
already installed but with OPA2604. I think that after Peter's comment everything is clear or so to say that someone has already made same conclusion as Peter.😀
Trigon.
already installed but with OPA2604. I think that after Peter's comment everything is clear or so to say that someone has already made same conclusion as Peter.😀 Trigon.
Attachments
Regarding 100 ohm resistors, untill you make up your mind what's better, don't remove the original 1K ones, but add 110ohms in parallel to those, so you can easily return to your previous setup.
The AD823 works well with 1k resistors so initially you don't even have to bother with replacing impedance.
The AD823 works well with 1k resistors so initially you don't even have to bother with replacing impedance.
What about break in issues? If you only put the AD823 and try it for a few hours it may not be enough time for it to show its true potential.
I hear people have the same issues when rolling brand new sets of tubes, its a pain in the *** to burn them all in and then try them.
I hear people have the same issues when rolling brand new sets of tubes, its a pain in the *** to burn them all in and then try them.
I gave it full 24 hours. That's about all I could stand it😉
OPA2604 has slightly darker character and AD823 seems to have a bit more presence, but AD chip is missing the fine layering an all the texture that I hear when I'm using OPA chip. Even bass seems to be better defined (tighter) and the pace of the recording is much more obvious.
After switching to AD823 I felt like the spirit of the performance suddenly disappeared, now that I'm back to OPA2604, I can easily sense it again😉
OPA2604 has slightly darker character and AD823 seems to have a bit more presence, but AD chip is missing the fine layering an all the texture that I hear when I'm using OPA chip. Even bass seems to be better defined (tighter) and the pace of the recording is much more obvious.
After switching to AD823 I felt like the spirit of the performance suddenly disappeared, now that I'm back to OPA2604, I can easily sense it again😉
Now that you have had a chance to play around with it do you think its the best preamp you have heard fullstop?
Or is it just better with the upgrades than when you first recieved it?
They have sold out of those pcb boards on that website 🙁
Or is it just better with the upgrades than when you first recieved it?
They have sold out of those pcb boards on that website 🙁
All I can say, it's much better than it was when I first listened to it. As it was in a stock form (and I'm talking here the 'S' version), I wouldn't like to keep it in my system. After the upgrades (which are only halfway though), I know it's much better than a passive, switching attenuator. It 'inriches" the sonics in a way that passive stages simply can't. With passive it seems pure and clean, but also a bit dry. The preamp provides liquidity, texture and layering, I didn't hear before. The 'ease' of presentation is astonishing and I can't get tired of that sound. Please keep in mind that my source is using passive I/V, but I don't think it's makes that much of a difference here.
As to the boards, all were sold out, but I believe some people bought more than they really needed and sooner or later they may become available fro private sales.
As to the boards, all were sold out, but I believe some people bought more than they really needed and sooner or later they may become available fro private sales.
I do not have any experiences with passive preamps, but from what I have read, the idea of of them sounding better because of the purity of signal is more theoretical than reality.
But in the latest version of Bound For Sound Marty de Wulf claims that the Sonic Euphoria linestage is the first passive he has ever been impressed with, it does not suffer from dryness or lacking in dynamics e.t.c. It uses an autoformer or something
But in the latest version of Bound For Sound Marty de Wulf claims that the Sonic Euphoria linestage is the first passive he has ever been impressed with, it does not suffer from dryness or lacking in dynamics e.t.c. It uses an autoformer or something
I'm using S&B102 transformer based attenuators and those are indeed a step above resistive volume switchers, no matter how good they are buit.