Is my preamp useless?
Just to add to the above, when these high capacitance interconnects (>200pf per foot) are used, they can cause a high frequency filter, not only with passives but also with the many tube preamps. This is another reason they have no place in hi-end audio. Thank god there are not too many of them around. Cheers George |
"Does it mean that all these highly regarded active preamps also have not been designed properly? So which one would you say is wrong: cables or active preamp? Milpai (System | Reviews | Threads | Answers | This Thread)" Neither is wrong. Audio components are usually designed with the understanding that they will be used in a wide variety of systems. Its impossible for any designer to make products that will be optimal in all systems. It just can't happen. That's why there's nothing wrong with the cables or the preamp. They just can't work for everyone in every situation. |
Just to give an example, A 10kohm passive preamp which all solid state sources can drive, has a worst case 2.5kohm output impedance. In the worst case of 2.5kohm, this passive preamp driving reasonable quality interconnects of 100pf per foot at 2mts long will give a high frequency roll off at -3db @ 106khz!!! And with just one meter interconnects it is -3db @ 212khz!!! And this is interconnects of 100pf, if you get good quality ones that are 50pf per foot, the HF roll off point off doubles again To -3db @ 212khz for 2mts!! And -3db @ 424khz for 1mt!! As you can see only dogs and bats can hear this kind of HF filtering. Cheers George |
Here is the graph of a 10kohm passive output impedance. On the left (vertical axis) is it's output impedance, for the given volume resistance (horizontal axis). As you can see at half volume rotation it is at the worst 2.5kohm output impedance, either side it's output impedance is lower. http://i.stack.imgur.com/cVUCc.png Cheers George |
I'm using my PS Audio Direct Steam with a BSG QOL unit (awesome) into a Pass Labs X350.5 Amp. The BSG QOL unit provides added gain and so much more texture than when I used my former Pass Labs Preamp. I use the PS Audio Direct Stream volume, and it usually runs between 60 and 65. With the PS Audio High filter engaged, the volume on the PS can run in the high 90's. However, I prefer to run it without the filter with the volume in the 60's. The BSG QOL also provides added analog inputs and outputs. One of the inputs is used for my Denon Home theater pass through in which the Denon controls the volume while playing Blu Rays from my Oppo. The BSG QOL also has dual analog outputs in which I run my dual JL F113 Subs. |
