Passive preamps

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AmpDesigner333

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Passive preamps
« on: 7 May 2016, 12:28 pm »
We're looking for people that use passive preamps....

What would you recommend?

Do you also have Marasvhino or other Cherry amplifiers?  Have you used active as well?

Lots of interest there, especially with transformer based units.  Thanks.

SteveMiller

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Re: Passive preamps
« Reply #1 on: 7 May 2016, 02:34 pm »
I have found a very sweet spot in the preamp arena for my system.  I've had many various preamplifiers including BelCanto, SimAudio, Wyred4Sound, Croft,Chord and more. Each one was of very high quality and very satisfying at the time.   But then, as usually happen we have the opportunity to hear something better, or simply get the notion there might be better.   When I tested DAC DAC direct into Maraschino I realized how much my preamps were covering up or burying in the mix.  So I embarked on a mission to find a preamp that would give me good volume control range my system, and the input switching options to add auxiliary sources down the road. In the end, the AudioZone PreT2 was the clear choice.  Priced much lower than many other units I have had, but offering absolutely pure sonics and amazing build quality. Functionality is well thought out and the size of the unit fits well with the form factor of cherry products too.

The PreT2 is a TVC circuit.  So, completely passively it gives you volume control by switching in or out multiple transformer taps and uses absolutely no resistors, diodes, or capacitors in the signal path.  High quality gold plated switches and densely potted transformers are mated with beautiful terminations on an extremely heavy chassis for its size.   A seriouse unit built right here in Toronto Canada.

The TVC system suffers no low level loss, no AC voltage variations, no static, no hum, and to these ears zero distortions or coloration of the signal fed.  If anything at very low levels the TVC circuit seems to drive the amplifier better somehow.  Things never get grey or flat, just quieter.  Then as you approach higher levels it gets lets more sound volume through.  It truly is undetectable, and that's driving 25ft interconnects, into Maraschinos on 102db speakers.   

http://audiooasis.com/blog/2013/10/2/audio-zone-pre-t2new-tvc-passive-preamp-with-xlr-and-rca-ino.html




SteveMiller

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Re: Passive preamps
« Reply #2 on: 7 May 2016, 02:38 pm »
For those interested, the AudioZone PreT2 is fully balanced throughout and it respects and preserves the differential signalling that Digital Amplifier Co products thrive on.  It will however accept rca in or out, providing the conversion to mix with XLR's at the same time.   Pretty cool piece.




konut

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Re: Passive preamps
« Reply #3 on: 7 May 2016, 02:43 pm »
SteveMiller, what other passives did you try?

poseidonsvoice

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Re: Passive preamps
« Reply #4 on: 7 May 2016, 05:43 pm »
FWIW, my TAPX build: http://www.audiocircle.com/index.php?topic=118082.0

Measurements: http://www.audiocircle.com/index.php?topic=115115.0

In my opinion, the LDR, TVC, AVC passive preamp (or at most +6dB) arena is pretty saturated with STRONGLY competitive pricing already. Plenty of choices with Tortugaaudio, Vinnie Rossi's LIO, DIYHifiSupply Django, Hornshoppe Truth, etc...

Best,
Anand.


glynnw

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Re: Passive preamps
« Reply #5 on: 7 May 2016, 07:10 pm »
I vote for Tortuga, after 30+ years of listening, including having owned a TVC just before I discovered the Tortuga.  And the base unit features remote volume and balance.

orientalexpress

Re: Passive preamps
« Reply #6 on: 7 May 2016, 10:00 pm »
I use Bent audio tapeX with my cherry plus I love it ,this one identical to mine http://www.audiocircle.com/index.php?topic=142753.0

Lap


bummrush

Re: Passive preamps
« Reply #7 on: 8 May 2016, 01:31 am »
My Coda at unity gain

SteveMiller

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Re: Passive preamps
« Reply #8 on: 8 May 2016, 02:06 am »
konut

I had for a few years been very satisfied with the Wyred4Sound STPse which as a passive, below unity, places just one high quality resistor in the attenuation. It's very good, but the buffer stages could be responsible for softening the signal somewhat.   I as well had the pleasure of test driving the TEO Liquid Audio preamp, although it's only a single ended device, but wired with the TEO special formula cabling.  Also, there were a few pro audio devices, that again placed just one resistor in signal path, but use different schemes of shunt or series resistance to attenuate. 

I think rather than comparing different passives, and arguing those merits, the point I wanted to make, and perhaps I missed it, is that the PreT2 is indistinguishable in my system from DAC direct, other than it lowers the volume when required.   I'm happy with it.   And guys, that's really the only point in listening.  To be happy, and hopefully at an affordable level of investment. 

Tommy's DAC DAC and Maraschino's deserve very high quality playmates! We are all interested to hear each other's success stories!


anwar1965

Re: Passive preamps
« Reply #9 on: 8 May 2016, 10:25 am »
I started with Audio Research REF 5SE, then used Bent Audio Tap-X fully-balanced copper autoformers, and finally settled with Tap-X fully-balanced silver autoformers.  No background noise and very high resolution indeed.  Volume attenuation for typical listening is around -30 to -20 dB.

AmpDesigner333

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Re: Passive preamps
« Reply #10 on: 23 Mar 2020, 09:13 pm »

kernelbob

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Re: Passive preamps
« Reply #11 on: 24 Mar 2020, 09:05 pm »
Hi all,

I highly recommend the Tortuga LDR controller.  I've used one for several years now.  The sound quality remains the best I've heard from either active or passive preamp/controllers.   A key to its performance is that there are no switches, potentiometers, stepped attenuators, or capacitors in the signal path.

I'm using the LDRxB which is the balanced version.  My Tortuga drives a bi-amplified system with a pair of Lampizator 211 True Balanced monoblocks (moving the the Pacific 211 monoblocks soon) on the M/T and a pair of Spectron Musician III Mk2 on the woofers.  The source is the Lampizator Pacific DAC which outputs 3V.  Plenty of volume.  I can generate volumes of the loudest orchestral passages (measured using a DB meter at live performances) using -12 dB attenuation on the Tortuga in my system.

All of the Tortuga's settings are controlled via software, so every control can be accessed from the provided Apple remote.  That makes it easy to instantly hear the differences that you make on the fly.  There's just about every control and set-up option you could want.

Input impedance settings are available in 1-kohm steps from 1k to 99k (in my balanced unit that's per phase).  My Pacific DAC sounds best seeing a high input impdance, I've settled on 97k per phase.  That optimum value varies in my system depending on the output tubes I use in the Pacific DAC.  By comparison, the Schiit DAC I used sounded best at around 67 kohms.  You can save any nine custom input impedance settings and switch between them using the remote while listening to the differences from your listening position.

If you use a balanced system, you can order the Tortuga with absolute phase/polarity control and yes, you can easily tell the difference.  This is very useful since the correct setting varies from one recording to the next.

An Achilles heel of many passive controllers is lean bass.  The Tortuga has full bodied bass with extremely deep extension to the lowest frequencies. 

Soundstaging is wide, deep, with precisely placed instruments & voices.  Individual instrumental lines in complex orchestrations are surprisingly easy to follow.

Best,
Robert

AvsFan

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Re: Passive preamps
« Reply #12 on: 27 Apr 2020, 02:24 am »
I'll chime in on this. Jesse at Pine Tree Audio just finished this very simplistic pre-amp for me . With an Alps RK27 Pot. It has a set of unbalanced/RCA stereo outs as well for dual subwoofers.
I will be having a custom/modded, DAC DAC 2HS going into the balanced in's and out to a pair of Golden Cherry Mono blocks powering my Magnepan LRS's. I am SUPER excited. I wanted to keep the signal as unaltered and simplistic as possible. We even talked about a remote volume control, but in the end, didn't want any chance of electronic noise or interference.












mfsoa

Re: Passive preamps
« Reply #13 on: 27 Apr 2020, 04:25 pm »
AvsFan those amps will be killer on those speakers!!

Let the world know how it goes.


Wind Chaser

Re: Passive preamps
« Reply #14 on: 27 Apr 2020, 04:38 pm »
By golly, it looks like Cherry product!  :thumb:

Wind Chaser

Re: Passive preamps
« Reply #15 on: 27 Apr 2020, 04:40 pm »
Avs,

How much did that one off cost?


AvsFan

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Re: Passive preamps
« Reply #16 on: 27 Apr 2020, 11:05 pm »
By golly, it looks like Cherry product!  :thumb:

Scary huh! Even has the same footprint. They were meant to go together.  :D

AvsFan

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Re: Passive preamps
« Reply #17 on: 27 Apr 2020, 11:05 pm »
Avs,

How much did that one off cost?

Thousands.........

Randy

Re: Passive preamps
« Reply #18 on: 28 Apr 2020, 02:56 am »
Hi all,

I highly recommend the Tortuga LDR controller.  I've used one for several years now.  The sound quality remains the best I've heard from either active or passive preamp/controllers.   A key to its performance is that there are no switches, potentiometers, stepped attenuators, or capacitors in the signal path.

I'm using the LDRxB which is the balanced version.  My Tortuga drives a bi-amplified system with a pair of Lampizator 211 True Balanced monoblocks (moving the the Pacific 211 monoblocks soon) on the M/T and a pair of Spectron Musician III Mk2 on the woofers.  The source is the Lampizator Pacific DAC which outputs 3V.  Plenty of volume.  I can generate volumes of the loudest orchestral passages (measured using a DB meter at live performances) using -12 dB attenuation on the Tortuga in my system.

All of the Tortuga's settings are controlled via software, so every control can be accessed from the provided Apple remote.  That makes it easy to instantly hear the differences that you make on the fly.  There's just about every control and set-up option you could want.

Input impedance settings are available in 1-kohm steps from 1k to 99k (in my balanced unit that's per phase).  My Pacific DAC sounds best seeing a high input impdance, I've settled on 97k per phase.  That optimum value varies in my system depending on the output tubes I use in the Pacific DAC.  By comparison, the Schiit DAC I used sounded best at around 67 kohms.  You can save any nine custom input impedance settings and switch between them using the remote while listening to the differences from your listening position.

If you use a balanced system, you can order the Tortuga with absolute phase/polarity control and yes, you can easily tell the difference.  This is very useful since the correct setting varies from one recording to the next.

An Achilles heel of many passive controllers is lean bass.  The Tortuga has full bodied bass with extremely deep extension to the lowest frequencies. 

Soundstaging is wide, deep, with precisely placed instruments & voices.  Individual instrumental lines in complex orchestrations are surprisingly easy to follow.

Best,
Robert

I also have the balanced Tortuga and agree with every word Robert says.  Tortuga is right here on Audio Circle so you don't have far to go.

AvsFan

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Re: Passive preamps
« Reply #19 on: 28 Apr 2020, 03:38 pm »
Avs,

How much did that one off cost?

And I was only kidding. $250! I can’t say how it compares to the other passive preamps out there, because I haven’t heard other ones. But I bet this is going to pass a pretty pure and clean signal right to my Golden Cherries. I don’t really see the point of expensive passive pre-amps. See that’s the problem with some so called high end audio companies building passive preamps that costs thousands of dollars. I could have very well said this passive pre-amp was $1000 and a lot of people would have been like oh, that’s not too bad. If someone can explain to me why there is a reason to spend a lot of money on a passive pre-amp, I’m all ears. As long as it’s a good design, implemented well, wired right and does what it’s supposed to do, pass a signal through as unaltered as possible to your amplifiers, isn’t that the point? But once again, I’m no expert, so I am open to others views and opinions. And let me be perfectly clear. This does not apply to other electronics. I’m talking strictly passive preamps. I get why there is a reason we pay more money for other parts of our systems.