I went from Active to passive, It was very difficult to get the passive working properly. It is hard work but it will be rewarded.
As a rule the output impedance of the source should be 10 times lower than the input impedance. My DAC has an output impedance of 50 ohms, my passive has an impedance of 1k (20 times 50 ohms) and my amps have an input impedance of 1meg. So it works nice, I tired impedances with my passives from 100k, 10k, 5k, 2.5k and 1.2k, believe me the diference from 1.2k to 1k is very noticeable, I get much better bass and fuller sound with 1k.
This is a shunt type resistor based passive with caddock resistors, and a resistor ladder going to ground, a pot does not work as good to ground!
I had a PLC and hated it....
I sometimes miss my Metaxas active SS preamp.
Best. |
Pubul57 If you want to get a feel of the passive you can get a Luminous Audio passive, they supposedly calculate the impedance and sell you the passive, it is a shunt passive with a pot to ground, A friend has one and it does let you get the feel of a passive...full resistor loaded is much better, I talked to Guy from Placcete and he told me all his passives come with a 10k impedance, this impedance can work for you, he also changes impedances according to the customers settings. You can buy a placette passive and see if it "fits" your system, Guy will help you out even if the preamp is used (very cool guy!) this way you can be sure you have the passive matcing properly. |
Hello Gmood1!!
Have you tried a resistive passive vs. a TVC in your system lately? I had a hard time but I finally got the match made and the resistors betters the TVC in my system, Im curious about your findings.
All the Best |
Gmood1,
I had a PLC, I heard it for the first couple of days and loved it...certain details were better, so I bought it from a friend, two weeks later I started to notice a lot of things were missing...bass, attack, detail altoghehter, there was probably some impedance problem because it really didnt sound good...we tried it in 3 different systems with similar results, once I noticed the drawbacks I cold hear them all the time in any system.
Anyway, I am glad it is working out for you, enjoy!!!
All the Best |
I have my passive attenuators are inside my mono amps, the attenuator is a couple of inches away from the input tube. I have good dynamics but my old SS preamp was much more dynamic! I guess thats what you loose with passives against active.
I used to have an outboard attenuator box and did not notice a lot of difference when I put the attenuators inside the amps. I did notice a big change when I used all resistors inside, I guess the big change was due mainly to resistors against the alps pot, more than the lenght of the cables...
Pubul57 please let us know how you do with the Placette passive and the changes you notice against the CAT, this is very important to me since I still have the bug for an active preamp. |
Darkmoebius:
Source EAD 7000 III DAC
Output voltage 2V
output impedance 50 ohms
Amps Leak TL12.1
Input sensitivity
148mV r.m.s. input gave 12 watts output at 1,000 c/s.
Input impedance 1 meg ohm
Perfect for a passive?
Speakers are 94 db sensitivity |
Darkmoebius: Yes very short speaker cables I actually have built a pair to my flavor mixing copper and silver transformer wire, right now I think I am missing a couple of copper strands to give it more body. The ICs are Gabriel Gold bought here in Agon, I also have Nordost Blue Haven but they are a bit forward and shy on bass, I tried Siltech SQ80 and they were too dark, Black Mountain were too light..Gabriel mixed good in my system, 1 meter between DAC and amps. 4 inches one strand kimber blue (from 8tc) from the attenuator to the input tube inside the amp :-)
I got the PLC partly because I got a good deal and because I heard better reviews of autoformer vs transformer...since I got the perfect setup for passives I might give the transformer a try, probably the Promiteus Audio since they are affordable. (say against th 6.5k for the AudioConsulting)
Atmasphere: I find Pubul57s question very ineteresting also, If you could design the perfect source-preamp-cables for your amps, would it be passive or active?
Thanks |
"People like Guy Placette and Emmanuel Go (who originally offered a passive design that is no longer avalailable) designed and built active preamps for a reason. "
Which is???
I think Pubul57 puts it very nicely, "passives are a cult item" if you are able, and knowledgeable enough, and have the right system for it, it is "magic" : if one of the above is missing, it wont work: Then you can get the active.
If you swap equipment a lot you will need the active also.
But lets ask them!
Another issue which I dont think is fair to apply it but it is real: a Passive Preamp is pretty cheap and there is really no way of making it very expensive (unless you use silver transformers I guess); but an Active Preamp can be sold for a lot of money, even without silver transformers! |
Atmasphere: I found that the resistance of the control changes the sound A LOT, huge changes and that worries me, I have been closing in on the best value for my system and I have always been going lower, now I am using 1k, the diference from 1k to 1.2k is big, mainly the instruments get more body and weight, dynamics are also better. With 10k there was no dynamics, the snare drum didt really move me it sounded like a stick...going lower its becomes more of a drum, fuller sound and it begins to move your belly when it hits (thats what I like!!)
With my active preamp I had huge dynamics and almost no transparency loss...the passive is more transparent and I have almost huge dynamics..If I had never heard the active that way I would be very happy with my passive right now.
I am going to try a 800 ohm control and see what happens!!
I am also using AN tantalum resistors since they give out a fuller body than the caddocks or vishay I tried.
I talked to Guy from Placette and he didnt recommend a 1k attenuator, he does not make it either...so I will have to get the active Placette then! If its 20 or 30 % better more transparent and dynamic its does sound pretty good...does it come with a phono section also?
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Congatulations Pubul57!!
As long as we are making announcements I would also point out that my dynamics quest with the passive preamp is over, now I got the dynamics of my previous SS preamp and the transparency of the passive, tweaks helped a lot for this, Ribbon power cables, 2 inch Spruce Wood bases on all my gear, and biamping!!! I now use my passive preamp to drive my mono amps and a Subwoofer....amazing!
Best |
Gmood1; I dont think you ever told us about the Bent NOH against the Promitheus on the TVC shoot out, what are your findings?
Best |
Well Tbg, I have the dynamics of active with my passive, carefull matching and testing was required but now I got transparency of passive and the dynamics of active... |
