[hjsouth]

Recently changed from active to passive preamp.  Surprised there is no circle about this specific topic.  I enjoyed the Khozmo with my Red Dragon mono blocks and Spatial Audio M3 Triode Master speakers.  I found the efficiency of the speakers and the amps to be very well suited for the passive.  In fact most active preamps in my system had to much gain.  I upgraded from the Khozmo passive, which I liked a lot, to the Hattor passive preamp.  The two are owned by the same person. The Hattor is a very nice upgrade from the Khozmo and I believe a heck of a good bang for the buck.  Highly recommended.  Sonically very similar in my system, but fit and finish a huge upgrade.  Anyone using passives, and what is your experience vs active preamps?

[TJHUB]

I switched to a passive (Tortuga LDR) a couple of years ago, and never looked back.  I LOVE my Tortuga.  It lets my source shine through.

[hjsouth]

I looked at the Tortuga but had already invested in the Hattor and Khozmo.  Really interesting technology.  Have you updated to the newest v .25?  Did you notice any change in sonics?  Would have loved to have heard that piece. 

[hjsouth]

BTW, checked out your system, very nice, and looks to be a dedicated listening room.  Your a"few" steps ahead of me.

[I.Greyhound Fan]

I built a passive Pass B1 preamp/buffer to use with my old Parasound A21 amp.  It sounds great.  Not is the same league as my BAT VK-51se preamp though.

[TJHUB]

I looked at the Tortuga but had already invested in the Hattor and Khozmo.  Really interesting technology.  Have you updated to the newest v .25?  Did you notice any change in sonics?  Would have loved to have heard that piece.

No.  I have the v2 and I am very content.  I may go balanced in the future, but only if and when I change my DAC. 

[Emil]

Everyone needs to try a passive in their system.

To scratch a long standing itch, I picked up a Placette for cheap. An eye opener to say the least.
Placed my Dehavilland Mercury 3 up for sale the next day.

I'm sure it doesn't work for some systems but it sure does with my 300B and Horns.

I have a  Tortuga on order and should have it  by the end of the week. I expect it to outperform the Placette

[RDavidson]

I built a passive Pass B1 preamp/buffer to use with my old Parasound A21 amp.  It sounds great.  Not is the same league as my BAT VK-51se preamp though.

The B1 isn't a true passive. It is active, but without gain. I'm a fan of this approach personally as you can get 99.9% of the transparency of a full passive, but without the worries of impedance mismatches and other complications that full passives can present.

[Emil]

The B1 isn't a true passive. It is active, but without gain. I'm a fan of this approach personally as you can get 99.9% of the transparency of a full passive, but without the worries of impedance mismatches and other complications that full passives can present.

Tortuga does address this issue.
From the website.

Adjustable Impedance   Nominal 20k by default | User may configure up to 9 additional impedance settings adjustable between 1k and 99k each | Once additional settings are initialized user may switch between the settings with live music to optimize input impedance for their system.

[C17FXR]

Everyone needs to try a passive in their system.

I could not agree more, went from an active and passive preamp (McCormack Micro Line Drive) then moved to the McCormack TLC with the Passive and buffered outputs.
The TLC has been back to SMc twice and is now their Signature buffered preamp.
The buffered outputs provided a more engaging mid to lower region and eliminated to problem associated with long interconnect, mine are 23 feet from pre to amp.

Funny now that I think about it my headphone amp is basically a passive/buffered preamp as well. 
I guess once you're addicted it's hard to give it up.

I remember trying an active while my TLC was at SMc getting upgraded, the soundstage seemed compressed, as if watching a smaller screen TV, everything was there just brought closed together.
I preferred the expansiveness the passive/buffered offered. I also remember that base notes and drums had a very forceful impact to them, I could see where that would work with some systems.

Just my to penny's for the conversation.

[poseidonsvoice]

I've been using my balanced diy TAPX for years: http://www.audiocircle.com/index.php?topic=118082.0

In the middle of last year, I changed the copper AVC's to silver AVC's: http://www.audiocircle.com/index.php?topic=118082.msg1615102#msg1615102

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

Conclusions? For now, I'm staying put 

Best,
Anand.

[SPL db]

I run a Reference Line Preeminence 1A Passive Pre-amp fed to my Atma-Sphere M60 monoblocks.  The volume is remote controlled which makes it very nice.

[RDavidson]

Tortuga does address this issue.
From the website.

Adjustable Impedance   Nominal 20k by default | User may configure up to 9 additional impedance settings adjustable between 1k and 99k each | Once additional settings are initialized user may switch between the settings with live music to optimize input impedance for their system.

Yes. Tortuga is the only full passive I'm aware of that offers impedance adjustments. Really excellent piece of engineering there.

[poseidonsvoice]

.... Really excellent piece of engineering there.

Ummm...really?

https://www.neurochrome.com/tortuga-audio-ldr3/

Don't shoot the messenger...

Best,
Anand.

[bavmike]

Slagleformer’s are my reference for analog volume controls. However one must insure the gainstage in the source driving them has a maximum output impedance of 10 ohms, and is capable of sinking/sourcing a minimum of 60mA current with absolute ease, if you want reference level performance from them.

When I hear stories of guys switching away from Slagleformer’s, once they tell me the DAC’s they used with them, the reason why becomes very clear.

[Jonathon Janusz]

Slagleformer’s are my reference for analog volume controls. However one must insure the gainstage in the source driving them has a maximum output impedance of 10 ohms, and is capable of sinking/sourcing a minimum of 60mA current with absolute ease, if you want reference level performance from them.

When I hear stories of guys switching away from Slagleformer’s, once they tell me the DAC’s they used with them, the reason why becomes very clear.

Mike, I've read you say this a few times so far on this forum.  I did a little digging in to it, and an old post from John Chapman seemed to suggest that he felt (based on his Tap-X passive pre design using Slagleformers) that a source at or below 60 ohms output impedance should be good to go, as that was roughly where his reference source was when designing/testing the Tap-X (I didin't remember reading any figures regarding current sinking; sorry about that).  Any thoughts as to what seems to be your difference of opinion on this point?

Then, taking you at your word for a moment continuing to pursue this, I spent a few hours over a few days searching for DACs that meet your recommended specifications... and came up very light (if not all but short) on a list of potential "best" matches for a DAC to mate up to the Slagleformers.

Setting aside your now unobtainium DAC, or any yet to be released DAC you may develop (because neither is available for all practical purposes right now), Could you (or anyone else who has been on a similar hunt) point me in the direction of any currently commercially available DACs that meet these recommended specifications?

Thanks!

[RDavidson]

Ummm...really?

https://www.neurochrome.com/tortuga-audio-ldr3/

Don't shoot the messenger...

Best,
Anand.

Interesting data point from a competitor. I'm surprised he doesn't have better things to say.

[bavmike]

Mike, I've read you say this a few times so far on this forum.  I did a little digging in to it, and an old post from John Chapman seemed to suggest that he felt (based on his Tap-X passive pre design using Slagleformers) that a source at or below 60 ohms output impedance should be good to go, as that was roughly where his reference source was when designing/testing the Tap-X (I didin't remember reading any figures regarding current sinking; sorry about that).  Any thoughts as to what seems to be your difference of opinion on this point?

Then, taking you at your word for a moment continuing to pursue this, I spent a few hours over a few days searching for DACs that meet your recommended specifications... and came up very light (if not all but short) on a list of potential "best" matches for a DAC to mate up to the Slagleformers.

Setting aside your now unobtainium DAC, or any yet to be released DAC you may develop (because neither is available for all practical purposes right now), Could you (or anyone else who has been on a similar hunt) point me in the direction of any currently commercially available DACs that meet these recommended specifications?

Thanks!

I'm not talking about just getting good performance, I'm talking about exceptional performance. The kind of performance that will blow any active preamp out of the water regardless of cost. No weak areas whatsoever.

You're right most DAC's don't meet these specs. This is why very few have experienced the best from Slagleformer's. If John was to recommend DAC's with the specs I recommend to use with his Slagleformer's, Slagleformer sales would have also been thin!

[TJHUB]

Interesting data point from a competitor. I'm surprised he doesn't have better things to say.

There’s that, but I also just found out I must love the sound of noise and distortion.  

To anyone reading this thread, seriously try a Tortuga and send it back if you don’t like it.  30-day return and cheap to ship back IF you’d want.

[bavmike]

Here's an example of the Slagleformer's with a proper gain stage before them:

http://www.6moons.com/audioreviews2/aurorasound2/1.html

But if that proper gain stage happens to be in the DAC instead, no need to spend $23000 for the balanced version just to have it in the preamp case.