Any thoughts on removing a preamp from your system

Hi Phusis, a well written self analysis of what you believe is happening, well done.

As for the BCA Roquefort using the word preamp, this is a bit of a misnomer, as it does the volume control in the digital domain before the digital to analogue conversion (dac) stage, and has also in the same section a switch ability for various digital inputs. "with 2 pcs. AES / EBU, 2 pcs. S / PDIF, 1. coaxial, 1. Toslink and 1. USB"

This can be very loosely called a "digital domain preamp" but shouldn't. The word preamp is to pre-amplify in the analogue domain, and there is no preamplifing done there, and I don't believe this unit has switchable analogue inputs without seeing the back, as then there would be no control over the volume, as that's done up river in the digital domain. It should just be called a digital domain volume control with digital input switching, like many others do, Wadia, ML, etc.

After the dac it seems it has the normal I/V (current to voltage) conversion stage, post dac filtering and output buffers. No analogue domain volume controled gain stages or analogue input switching.

https://translate.google.com.au/translate?sl=da&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.studiosound.dk%2Fcddac%2Froquefort%2F&edit-text=

Cheers George

Hcalland, if your phono stage has enough gain by itself by comming out of aux and bypassing the preamps tube line output stage, then yes you are getting rid of an unnecessary tube gain stage and the result will be more transparency.

Todays sources (phono,cdp,dacs) all have enough gain by themselves to drive most amps to full output, why add another preamp gain stage, only to knock the gain of the source back down with the volume control and creating more noise.

Just read what Nelson Pass has to say about it here.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1400932591&openflup&6&4#6

Cheers George

06-05-14: Stewie
I have a passive pre in my system right now and the music sounds great: tubes on the top end, ss on the bottom, and I have no idea whether impedance matches or doesn't match

Hi Stewie, if you tell me the input impedance of both your tube and SS amps, and the output impedance of your source. I can let you know if your bi-amped system is passive friendly and with what value passive pot.

Cheeers George

Hello guys

This is my first post and I have been on Audiogon for a number of years now.

My question to the group is, have any of you removed your preamp completely from your system? Run your front ends straight to your amp? And, what benefits have you noticed, if any.

And finally, if you have used a passive preamp in your system, what are your thoughts on the setup?

I understand one would need to have some sort of "pot" in the signal path to regulate volume.

Herb

Hi Herb, look at this thread, it will explain most of all you need to know. And look at what Nelson Pass has to say about passive preamps in the 7th post.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1400932591&&&/Passive-preamp-w-Rogue-Medusa-and-Rega-D

And keep an eye on this thread for results for direct in observations on the sound when he does it.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1401842543&&&/Mark-Levinson-no-20-monoblocks

Cheers George

For the same reason Phusis, that's why I called my product the "Lightspeed Attenuator", as it's a passive attenuator, as there is no preamplifying going on inside it.

Cheers George

From what a member has sent me O_holter, I don't think the 34A has an active preamp in it.
Both the Ming Da MC34A and MC34B are very similar and are poweramps with a 100kohm passive volume control and input switching on the input.
The B costs $100 more as it has triode switchability and uses 6L6 instead of EL34. See the circuit diagram with just the 100kohm passive pot on the input tube to the poweramp input tube.

http://www.pastisch.se/EF/Ming%20Da%20MC34B%20schematic%20mod%201.gif

Cheers George

Stewie hi, you have no problems as far a I can see with these impedances.

Interconnect capacitance is the more important factor to you as you are bi-amped.
From the Carnary to your amps, because you are (bi-amped) and using two x interconnects per channel, I would use interconnects of 2mts or less, and of less than <50pf (picofarad) capacitance per ft. If only using 1mt lengths, then 100pf per ft is fine. This is so you will maintain proper high frequency extension.
Any decent interconect maufacturer should know this and should have it on their specs

Cheers George