Passive Linestage Exploration

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
I am going to do a series of reviews on passive linestages. I know some companies
market them as "preamps" but since there is NO amplification stage, i feel that is a bit
off the mark.

First, there was a thread started a few years back here..but I decided to start a new one
to go with a clean slate.

http://www.whatsbestforum.com/showthread.php?284-Passive-Preamps&p=2244&viewfull=1#post2244

I plan on exploring the premise that a passive linestage/attenuator offers the following benefits:

-one less gain stage
-one less power supply
-fewer parts
-less noise

The other factor is most source components have more than enough gain/voltage to drive most
power amps. Exceptions apply of course.

There are basically two types of passives:
TVC (Transformer Volume Control/Autoformer etc) and potentiometer types.

TVC types are considered superior due to impedance matching between source and amp, higher
transparency, and more precision. The big disadvantage is cost.

Potentiometer types can be excellent as well, and they cost a lot less to make.

So far I have the following units lined up:

-Music First Classic V2
http://www.mfaudio.co.uk/classic.htm

-CIA PLC
http://www.ciaudio.com/products/PLC1MKII

-Luminous Audio Axiom II:
http://luminousaudio.com/axiom2.html

-Dan Meinwald of E.A.R. USA is going to try to get me a Townshend Allegri:
http://www.townshendaudio.com/allegri/

All comments and input welcome!:D
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
All comments and input welcome!:D

Oh no they are not. You need to caveat that statement by saying only if the comments agree with your comments and they like your reviews. Otherwise, people are likely to be told by you that they are a "black cloud" and nobody likes them. That's the treatment I received when I made the mistake of providing honest feedback to your reviews.
 

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
Oh no they are not. You need to caveat that statement by saying only if the comments agree with your comments and they like your reviews. Otherwise, people are likely to be told by you that they are a "black cloud" and nobody likes them. That's the treatment I received when I made the mistake of providing honest feedback to your reviews.

I respectfully ask if you have nothing to say about the topic at hand, then abstain from comment.

 

still-one

VIP/Donor
Aug 6, 2012
1,633
150
1,220
Milford, Michigan
I plan on exploring the premise that a passive linestage/attenuator offers the following benefits:

-one less gain stage
-one less power supply
-fewer parts
-less noise


All comments and input welcome!:D

Could you explain why you believe that removing any or all of these will get you closer to whatever sound you are looking for?

Jim
 

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
Could you explain why you believe that removing any or all of these will get you closer to whatever sound you are looking for?

Jim

Just to clarify, this is a theory. I am not claiming this is true beyond all doubt!

Would you not agree, that in THEORY, a shorter signal path, one less power supply, less parts is better?

Also, again, talking theoretically, I can only surmise the more gain stages, the further you are away from the original wave form.
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
Could you explain why you believe that removing any or all of these will get you closer to whatever sound you are looking for?

Jim

Jim-First of all, the statements you questioned weren't worded correctly by Andre which means I am more of a black cloud for speaking the truth. Instead of saying "one less gain stage" and "one less power supply," Andre should have said a passive preamp has no gain stage and no power supply. Power supplies and gain stages in active preamps can be quite complex and can have more than one active stage. For instance, active preamps that only have one gain stage invert phase. Active preamps that don't invert phase have at least two gain stages.

Passive preamps can only reduce gain, they can never increase it. Many people that have been around this hobby for years understand that an active preamp is the heart of a stereo system. JA mentioned that several times in his review of the Pass Labs XP-30 line stage in the April 2013 edition of Stereophile. I personally wouldn't dream of not having an active preamp in my stereo system.
 

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
Jim-First of all, the statements you questioned weren't worded correctly by Andre which means I am more of a black cloud for speaking the truth. Instead of saying "one less gain stage" and "one less power supply," Andre should have said a passive preamp has no gain stage and no power supply. Power supplies and gain stages in active preamps can be quite complex and can have more than one active stage. For instance, active preamps that only have one gain stage invert phase. Active preamps that don't invert phase have at least two gain stages.

Passive preamps can only reduce gain, they can never increase it. Many people that have been around this hobby for years understand that an active preamp is the heart of a stereo system. JA mentioned that several times in his review of the Pass Labs XP-30 line stage in the April 2013 edition of Stereophile. I personally wouldn't dream of not having an active preamp in my stereo system.

No, I did not make incorrect statements. However, maybe I was not clear.

I meant one less gain stage (or more!) one less power supply etc...in the ENTIRE SYSTEM. I realize Professor, that an passive "preamp" has no gain stage
or power supply, hence no need to plug it into the wall.

Secondly, YOU would not dream of having not having an active preamp. That is totally fine, and definitely a preference.
No knocking you there.
 

still-one

VIP/Donor
Aug 6, 2012
1,633
150
1,220
Milford, Michigan
Just to clarify, this is a theory. I am not claiming this is true beyond all doubt!

Would you not agree, that in THEORY, a shorter signal path, one less power supply, less parts is better?

Also, again, talking theoretically, I can only surmise the more gain stages, the further you are away from the original wave form.

I have no desire to derail your thread debating any differences in our preferences. From your response it seems your goal is a system that recreates the music as close as possible no matter the quality of the recording. Now I understand.

Jim
 

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
I have no desire to derail your thread debating any differences in our preferences. From your response it seems your goal is a system that recreates the music as close as possible no matter the quality of the recording. Now I understand.

Jim

Jim, nothing to derail! I want to see an exchange of views No heated debates really apply here because there is no right or wrong.

You are correct...in your response, the goal would be to get as close as possible to the source.
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
No, I did not make incorrect statements. However, maybe I was not clear.

I meant one less gain stage (or more!) one less power supply etc...in the ENTIRE SYSTEM. I realize Professor, that an passive "preamp" has no gain stage
or power supply, hence no need to plug it into the wall.

Secondly, YOU would not dream of having not having an active preamp. That is totally fine, and definitely a preference.
No knocking you there.

I'm glad that I have graduated from a "Black Cloud" to a "Professor." Or is that a Professor with a Black Cloud? And while I'm being a "Professor," your fourth sentence above should have said "a passive preamp" and not "an passive preamp." You now say you meant "one less gain stage (or more!) one less power supply etc...in the Entire SYSTEM" which is another grammatically incorrectly structured sentence and also electrically wrong. Even SS power supplies have rectifiers, low voltage and high voltage sections (high voltage being a relative term compare with tube power supplies). Tube preamps will have a rectifier, heater power supply, a bias supply, and a high voltage supply for the tube anodes.
 

rbbert

Well-Known Member
Dec 12, 2010
3,820
239
1,000
Reno, NV
...I personally wouldn't dream of not having an active preamp in my stereo system.

I love my Pass INT-150 (according to Pass, essentially a passive volume control and switching put in front of an X-150.5), and hopefully will never go back to an active pre-amp.
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
I love my Pass INT-150 (according to Pass, essentially a passive volume control and switching put in front of an X-150.5), and hopefully will never go back to an active pre-amp.

You may love it, but it is not a pure passive preamp: There is no preamplifier per se in the Pass integrateds, but instead, a slightly modified version of the gain stage found in each of the regular Pass amps. As Nelson Pass told me, "First there is a selector switch, which is just relays, and then there's a buffer that drives the volume control. The output of that goes to the amp, and then you're done. There's not a lot there."

Bottom line is the fact there is an active gain stage-it's the buffer that drives the volume control.
 

rbbert

Well-Known Member
Dec 12, 2010
3,820
239
1,000
Reno, NV
Is a buffer an active gain stage, or just an impedance matcher?
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
Is a buffer an active gain stage, or just an impedance matcher?
In your case according to the description I posted above, it is an active gain stage.
 

Andre Marc

Member Sponsor
Mar 14, 2012
3,970
7
0
San Diego
www.avrev.com
Hello,

I would like to point out, very carefully avoiding slander, that the Passive TVC to hold them all is maybe this:

http://www.audio-consulting.ch/?Products:Preamlifier:Silver_Rock_TVC

I have used a silver rock "pre" as a simple volume control to ameliorise the digital volume control of my Wadia S7i (so it always stays in the high 90ties) - no personal affilitation with that company..

Thanks for the link. Very nice looking piece. I would bet it cost a fortune. Low volume, Swiss made, exchange rate etc....

Of course I would love to try it.
 

rbbert

Well-Known Member
Dec 12, 2010
3,820
239
1,000
Reno, NV
In your case according to the description I posted above, it is an active gain stage.

According to the Pass web site, the INT amps have just 2 gain stages, as compared to "6 to 9" in a typical integrated. So this would mean that the X.5 amps are just a single gain stage (if the buffer is one, that leaves only one)?
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
According to the Pass web site, the INT amps have just 2 gain stages, as compared to "6 to 9" in a typical integrated. So this would mean that the X.5 amps are just a single gain stage (if the buffer is one, that leaves only one)?

I honestly don't know. I do believe there have been several Pass amps that only had a single gain stage. So I wouldn't be surprised if the preamp section had one gain stage and the amp had one gain stage. Someone who is more familiar with Pass gear should be able to provide a definitive answer to your question. Typical "pure" passive preamps only have input jacks, a source selector, and a volume pot. There are no active components inside them which require a power supply.
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing