TOUR of LDR3.V25 Passive Preamp with new V25 LDR preamp controller

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tortugaranger

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Hello, I'm really thinking of going Passive and the LDR3 looks like the perfect preamp. My goal is total noise free, black background. I just purchased a great deal (discontinued--stock still exists) on a new NuForce STA200 class a/b power amp. This amp blows me away on my system. Anyway, I am running ZU omen Defs (ii) which are quite sensitive (101db, plus super tweeter). I hear a slight hiss with sizzle noise (very faint) thru speakers. I took my Peachtree NOVA PRE out of the system and tried my Oppo direct to amp (switched volume to variable) and tried the Bluesound NODE 2 streamer direct (switched volume to variable) and everything was dead quite. On the Nova pre, I bypassed the "gimmicky" tube and the noise was still there. So it seems the noise is coming from the Peachtree. To be honest, the noise is so faint, i only hear up close. However, I know it's there now...so I might as well address as I continue to upgrade my system.

The Schiit Freya seems to have some noise issues as well for some users. Channel Islands preamp looks nice.

Just curious from Tortuga users, is the LDR3 dead quiet?

As others have noted, there's no discernible noise introduced by the Tortuga LDR passive preamps. Of course if there's noise coming in from a source, that noise gets passed through only attenuated. There's no secret to why the LDR3 and our other passive models are dead quiet. Simply put there's no active direct contact between a power supply and the incoming audio signal as there is in all conventional active preamps. The noise you hear to varying degrees from many active preamps is actually the residual noise coming from the power supply. Better active preamps have better power supplies with better filtering and PSRR (power supply rejection ratio) and thus tend to be quieter. Still, when cranked up high, most active preamps produce some level of hiss that can usually be heard with the ear close to the speakers while no music is playing. In this respect passives are usually always quieter with blacker backgrounds and more space between the notes.

One possible exception to this is when mating a passive preamp to certain amplifiers that are DC (direct) coupled. Some direct coupled amps are sensitive to the presence of any DC offset in the signal coming from the amp. A passive preamp doesn't create a DC offset but it doesn't remove an either.  If there's a DC offset coming from a source, it gets passed through to the amp. With an active preamp, such offsets are most often blocked via either an input or output coupling capacitor - or both. That same DC coupled amp may also be fussy about connecting to a passive preamp if the preamp's output impedance is too high (too high for that specific amp, not too high for others). The net downside in these instances can be noticeable hum. While Tortuga passive preamps do have adjustable input impedance, the output impedance is inextricably linked with the input impedance and the resulting output impedance will never be flat/constant and may be too high for a particular DC amp.

The vast majority of amps are AC coupled and not DC coupled. Thus, the above exception has proven to be quite rare in practice. Plus with our 30 day in-home buy-try-decide audition policy you'll KNOW after putting one in your system if yours is an exceptional case or more typical. We don't hang people out to dry if our preamp isn't a good fit for your system. Just return it within the 30 day audition window for full refund less your cost for return shipping.

Best,
Morten

arcman67

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Hi arcman67,

Sound to me like grasping at straws to find some reason to throw stones at the Tortuga.



Not trying to sound snarky, I don't think anything I read (or said myself) was throwing stones at the Tortuga. I'm new to passive and like anybody with some sense, I do research. The questions I asked were results of repeated "possible cons of going passive" that I saw in regards to passives in general. So I am asking owners who have used the Tortuga specifically about the common issues with passives I have heard about.

As for input mismatch, I was just curious if, with most modern components, would it be less likely to switch from let's say input one at a comfortable volume, then switch to input two and be almost muted and I would have to jack volume knob quite a bit. Not really a Tortuga issue, its all about the actual components. But, is that a major concerned if using modern (non vintage) components.

Morton did a great job answering my questions plus 30 days is a great way to see for myself



arcman67

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As others have noted, there's no discernible noise introduced by the Tortuga LDR passive preamps. Of course if there's noise coming in from a source, that noise gets passed through only attenuated. There's no secret to why the LDR3 and our other passive models are dead quiet. Simply put there's no active direct contact between a power supply and the incoming audio signal as there is in all conventional active preamps. The noise you hear to varying degrees from many active preamps is actually the residual noise coming from the power supply. Better active preamps have better power supplies with better filtering and PSRR (power supply rejection ratio) and thus tend to be quieter. Still, when cranked up high, most active preamps produce some level of hiss that can usually be heard with the ear close to the speakers while no music is playing. In this respect passives are usually always quieter with blacker backgrounds and more space between the notes.

One possible exception to this is when mating a passive preamp to certain amplifiers that are DC (direct) coupled. Some direct coupled amps are sensitive to the presence of any DC offset in the signal coming from the amp. A passive preamp doesn't create a DC offset but it doesn't remove an either.  If there's a DC offset coming from a source, it gets passed through to the amp. With an active preamp, such offsets are most often blocked via either an input or output coupling capacitor - or both. That same DC coupled amp may also be fussy about connecting to a passive preamp if the preamp's output impedance is too high (too high for that specific amp, not too high for others). The net downside in these instances can be noticeable hum. While Tortuga passive preamps do have adjustable input impedance, the output impedance is inextricably linked with the input impedance and the resulting output impedance will never be flat/constant and may be too high for a particular DC amp.

The vast majority of amps are AC coupled and not DC coupled. Thus, the above exception has proven to be quite rare in practice. Plus with our 30 day in-home buy-try-decide audition policy you'll KNOW after putting one in your system if yours is an exceptional case or more typical. We don't hang people out to dry if our preamp isn't a good fit for your system. Just return it within the 30 day audition window for full refund less your cost for return shipping.

Best,
Morten


Thanks Morten for the time you have taken to answer my questions. Really, it does not look like I am "out anything" by trying the Tortuga. Plus, the wife wants me to move toward minimal designed stereo gear. She was glad I got rid of my old B&K amp with large rack handles on the front. The Tortuga matches well with the appearance of my new Nuforce amp

http://www.audioadvisor.com/prodinfo.asp?number=NUSTA200


kernelbob

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Not trying to sound snarky, I don't think anything I read (or said myself) was throwing stones at the Tortuga. I'm new to passive and like anybody with some sense, I do research. The questions I asked were results of repeated "possible cons of going passive" that I saw in regards to passives in general. So I am asking owners who have used the Tortuga specifically about the common issues with passives I have heard about.

I didn't mean to imply that you were being "snarky".  The exact statement I was referencing was...
Any issues with loss of dynamics,major out mismatches from input to input, etc that all the naysayers point to?

My response was directed to "all the naysayers", not that this was your statement or opinion.  I know that your comments were in no sense an attack nor were they out of line.  Mine were certainly not intended to be such.

Based on my experiences with other passive controllers, I was also skeptical of another passive unit.  However, the Tortuga has actually improved the dynamics (macro and micro) in my system.  That was quite a surprise.

Best,
Robert

tortugaranger

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...... would it be less likely to switch from let's say input one at a comfortable volume, then switch to input two and be almost muted and I would have to jack volume knob quite a bit. Not really a Tortuga issue, its all about the actual components. But, is that a major concerned if using modern (non vintage) components.

All Tortuga preamps remember the volume level setting last used with each input. When you switch back to given input the volume is automatically set to the volume last associated with that input. There's a global override to this which limits the maximum initial volume when switching inputs. That global override is set at 50%  volume by default but can be adjusted up/down by the user. This override prevents the user from switching to an input that may have used with home theater gear with the Tortuga volume set at 100% for home theater bypass.

Cheers,
Morten

kernelbob

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Thanks Morten.  I forgot that the volume setting of each input is retained.  For anyone interested in the all the features, there's in-depth documentation on the Tortuga website.

Robert

mlundy57

I got the unit and just finished putting it my system and turning it on. That's as far as I can go since there are not any instructions with it and the UI is not intuitive. I'm on my way over to the Tortuga web site to see if I can find some instructions.

Mike

WC

Mike,

Look for the controller instructions under preamp controls. I was able to figure it out, but it did take looking at the instructions.

tortugaranger

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I got the unit and just finished putting it my system and turning it on. That's as far as I can go since there are not any instructions with it and the UI is not intuitive. I'm on my way over to the Tortuga web site to see if I can find some instructions.

Mike

Been a bit preoccupied with hurricane Irma preparations but forgot to mention that the last participant discovered one of the two outputs was bad so heads up on that if you get no output just use the other pair. No doubt all the traveling has rattled a connection loose.

The V25 controls are explained in detail in the product documentation under Support in main menu. Select Preamp Controls - Apple Control Versions - V25 Apple Remote Guide

mlundy57

OK I found the guide. Just printed it out so back upstairs I go.

If one of the pairs of outputs doesn't work I may have a problem. My speakers are 2 part units so I use 2 outputs off the preamp. One output is connected to the bass modules' plate amps while the other output passes through an in-line filter to roll off the bottom octave on it's way to the power amp for the midrange/tweeter unit. 

If one of the outputs is bad I'll have to rig up a way to split the signal off the output that does work. What effect would this have on the performance of the unit?

Mike

tortugaranger

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If one of the outputs is bad I'll have to rig up a way to split the signal off the output that does work. What effect would this have on the performance of the unit?

Mike


With decent hardware I'd expect no downside. This is essentially what's done internally anyway.

mlundy57


With decent hardware I'd expect no downside. This is essentially what's done internally anyway.

OK if one pair doesn't work I'll get ahold of a couple Y splitters. Thanks

Good luck with Irma. Take care and be safe.

Mike

mlundy57

It's up and running. When I first started playing music the volume control didn't have any effect. The numbers would go up and down but the volume didn't change unless I ran it all the way down to 0. Then it almost totally muted. 0 would be mute, 1 would be very loud and didn't change regardless of where I set the volume.

I ran the auto calibration and that fixed the issue. Volume control is working properly now

Mike

tortugaranger

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It's up and running. When I first started playing music the volume control didn't have any effect. The numbers would go up and down but the volume didn't change unless I ran it all the way down to 0. Then it almost totally muted. 0 would be mute, 1 would be very loud and didn't change regardless of where I set the volume.

I ran the auto calibration and that fixed the issue. Volume control is working properly now

Mike

Hi Mike,

The challenge with sending a unit on a tour is there are opportunities for someone to change the configuration of the preamp to render it inoperable until corrected. One of the downsides of the adjustable impedance feature is a casual user can easily change the impedance setting/level incorrectly. This is the equivalent to giving the preamp an undefined/empty attenuation schedule so volume control does not respond normally. By rerunning autocal you initialized the attenuation table for whatever impedance setting the unit was set at.

The solution to this is a revision to the firmware around the adjustable impedance feature to make it impossible to set the impedance incorrectly to an undefined setting. "Undefined" is another way of saying an impedance setting has not been initialized through an autocal cycle. Once the firmware is revised, the preamp will simply revert to a previous known setting if the user puts it in an undefined/uninitialized state.

Enjoy,
Morten

tortugaranger

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Next stop on the tour is srclose in Oklahoma.

1) audiogurujax (FL)
2) WC (IL)
3) rklein (OH)
4) ozarktom (MO)
5) mlundy57 (OK)

6) srclose (OK)
7) mrvco (CO)
8 ) tubeburner (WA)
9) SFdude (WA)
10) mamba315 (CA)
11) SoundsGood (LA)

rklein

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Hi Mike,

The challenge with sending a unit on a tour is there are opportunities for someone to change the configuration of the preamp to render it inoperable until corrected. One of the downsides of the adjustable impedance feature is a casual user can easily change the impedance setting/level incorrectly. This is the equivalent to giving the preamp an undefined/empty attenuation schedule so volume control does not respond normally. By rerunning autocal you initialized the attenuation table for whatever impedance setting the unit was set at.

The solution to this is a revision to the firmware around the adjustable impedance feature to make it impossible to set the impedance incorrectly to an undefined setting. "Undefined" is another way of saying an impedance setting has not been initialized through an autocal cycle. Once the firmware is revised, the preamp will simply revert to a previous known setting if the user puts it in an undefined/uninitialized state.

Enjoy,
Morten

This is what happened to me...  I apologize for my tardiness in reporting back on my time with the Tortuga pre.

The only way I got to an appropriate volume was to run the volume control all the way up to 75+.  I should have called Morten to get the unit back to the correct configuration or go on his website.  I was in between business trips and had a limited time with the unit.  Unfortunately, I most likely did not hear what this preamp could really do.

Regards,

Randy

Tubeburner

Hi Morten,

You can take me off the Tour list since I ordered a LDR3v25 and I don't plan on sending it back. I have one in house and this will be my second for a bi-amp setup.

Everyone, please read the on line control and settings as it makes a world of difference on the sound.

Thank you Kernelbob for your help and recommendations.  :D


tortugaranger

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Next stop on the tour is mrvco in Colorado.
I've taken tubeburner off the list since he's is now a Tortuga Audio customer twice over.  :thumb:

1) audiogurujax (FL)
2) WC (IL)
3) rklein (OH)
4) ozarktom (MO)
5) mlundy57 (OK)
6) srclose (OK)

7) mrvco (CO)
8 ) tubeburner (WA)
9) SFdude (WA)
10) mamba315 (CA)
11) SoundsGood (LA)

mlundy57

I was impressed enough with the tour unit I'm going to build a 6 input version.

Mike

WC

I have a 4 input version on order. Someday it will show up.  :D