[tortugaranger]

I ordered a pair of Burr Brown OPA2134, I haven't opened up my preamp but is there one or two that need to be replaced?

Just one is needed. They are dual channel op amps.

[Hikmer]

Just one is needed. They are dual channel op amps.

I swapped out the op amp with the Brown Burr and gave it a listen, not critical but didn't hear anything that caused concern.  For the most part, swapping this out is like an adult version of Operation.  If your intent is to let people "roll" their own, perhaps a socket that is a little easier to use.  I've done this before with a Sutherland phono preamp and the sockets in that until had more user friendly opamp sockets. 

Waiting on a few other changes to my system to settle down before I give a critical review. 

[tortugaranger]

I swapped out the op amp with the Brown Burr and gave it a listen, not critical but didn't hear anything that caused concern.  For the most part, swapping this out is like an adult version of Operation.  If your intent is to let people "roll" their own, perhaps a socket that is a little easier to use.  I've done this before with a Sutherland phono preamp and the sockets in that until had more user friendly opamp sockets. 

Waiting on a few other changes to my system to settle down before I give a critical review.

Yes, the op amp is not exactly located where there's a lot of room - pulling out the 2 socketed gain modules on either side helps open up the access. As to the socket itself, the term "user friendly" and most any DIP socket do not go well together. That said, we do use a very high quality milled/machined socket made with BeCu - not a cheap socket. Doesn't mean it's easy - pins have to aligned just so - same as any DIP socket.

[Mjw21a]

Well,  I've placed an order for the active version. I believe this will be a worthy successor to the Dacgear LDR Pre Mk2 I currently run in my main system as I bi-amp. I'll move the Dacgear to my second system.

If it sounds at all Bright I'll order a Burr Brown OPA or maybe Burson V6 Vivid.

[Mjw21a]

Will a Sonic Imagery Labs 994Enh-Ticha work and fit inside this unit?  It's physically wider than taller discrete OPAMPS like the Burson.

[tortugaranger]

Will a Sonic Imagery Labs 994Enh-Ticha work and fit inside this unit?  It's physically wider than taller discrete OPAMPS like the Burson.

I've not measured this but eye-balling the available space and looking at that Sonic Labs unit online my guess is it will fit just barely. May have to push the adjacent trim pot out of the way a little. Worst case scenario you end up with a 8DIP pin socket extender to raise the effective opamp socket up high enough but I don't think that will be necessary.

[Mjw21a]

Mmm, I think I'll give it a go. From what I've read it sits between the Burson V6 Classic and Vivid in terms of sonics. Sounds interesting as each of those OPAMPS do something I like though neither quite do it all for me. Better than Sparkos though which are a little bright and thin in comparison.

I'm really looking forward to getting your active pre in place. 

[Mjw21a]

Recieve d it today. Upon first powering on I was a little disappointed vs my DACGEAR LDR h as it's getting some time on it things seem to be improving. Makes sense I guess as there are active components should benefit from burn in.

One other this n be I noticed is when using my the volume knob it's sometimes unresponsive though there appears no such issues with the be remote?

I'll listen some more later and see if I can get a better feel for it. More use needed to evaluate.

[Mjw21a]

Ok, now it's has a bit more warm up and I've been able to have a bit more of a listen I note the following ad improvements over my DACGEAR LDR Pre MK2:

1. Noticeably improved dynamics (contrast between quiet and loud)
2. Improved decays, especially high hats
3. Bass initially seems less, then I notice bass notes and instrumentation I've never heard before. It's more transparent.
4. An overall more natural sound though reveals more flaws in  recordings. Overall everything sounds better though warts and all.
5. An ever so slightly smoother and more natural presentation

Overall with minimal burn in this is a noticeable improvement. It won't be going back. Now to reprogram my Logitech Harmony remote. 

[tortugaranger]

Ok, now it's has a bit more warm up and I've been able to have a bit more of a listen I note the following ad improvements over my DACGEAR LDR Pre MK2:

1. Noticeably improved dynamics (contrast between quiet and loud)
2. Improved decays, especially high hats
3. Bass initially seems less, then I notice bass notes and instrumentation I've never heard before. It's more transparent.
4. An overall more natural sound though reveals more flaws in  recordings. Overall everything sounds better though warts and all.
5. An ever so slightly smoother and more natural presentation

Overall with minimal burn in this is a noticeable improvement. It won't be going back. Now to reprogram my Logitech Harmony remote. 

1. Noticeably improved dynamics (contrast between quiet and loud)

Even with the solid state active/buffer output stage these preamps have a dead quiet background. I get this comment often.

2. Improved decays, especially high hats

I think this is related to #1 in that subtle details are more clearly present and unlikely to be masked.

3. Bass initially seems less, then I notice bass notes and instrumentation I've never heard before. It's more transparent.

Bass is one area that where we usually get consistent comments about bass being noticeably strong but not overly so.

4. An overall more natural sound though reveals more flaws in  recordings. Overall everything sounds better though warts and all.

"Natural sounding" is probably the THE most common comment we get on our LDR preamps. But you hear what's there....like it or not. Can't hide from the recording quality.

5. An ever so slightly smoother and more natural presentation

That was my own personal impression the first time I started working with LDR attenuation.

[Mjw21a]

My only real gripe is that the volume knob when used is regularly unresponsive for a second or two. I believe this is a firmware bug.

Another is settings seem to be lost if the unit is powered down
 My work around for this is to never turn it off, and this is a valid work around due to the user replaceable nature of your LDR modules. It also simplified my systems operation which makes my wife happy.

[tortugaranger]

My only real gripe is that the volume knob when used is regularly unresponsive for a second or two. I believe this is a firmware bug.

Another is settings seem to be lost if the unit is powered down
 My work around for this is to never turn it off, and this is a valid work around due to the user replaceable nature of your LDR modules. It also simplified my systems operation which makes my wife happy.

**  Updated **
I'm curious to know more about these issues (response delay from volume knob & lost settings) since we have no evidence of this happening in any units we're currently building/commissioning and are not receiving similar complaints from others. Not saying these problems aren't real, only that we're ignorant of this happening. Any further info, pics, video etc you can provide documenting this will be appreciated and may prove helpful getting it resolved.
We found the root cause of the lost settings. Maybe also the delayed response. We made a fairly significant firmware update just before your unit was shipped. It's clear now that we managed to introduce a bug that we did no observe so we didn't catch it. It's clear now what happened and a fix is being prepared.

[Mjw21a]

Excellent, thanks so much Morten for your (rather exceptional) response to this. 

I look forward to the updated firmware. I had read about your incredible support, but to experience it is another thing entirely. Better than I’ve ever experienced before.

[Mjw21a]

Here’s a short video of the volume knob issue Morten. In my mind definitely a firmware issue rather than hardware based on the units observed behaviour. I.e. The volume knob will wake it up but there's a delay before it will accept volume change. The bug doesn't seem to affect control via the remote thankfully.

https://drive.google.com/file/d/1crMqpzeiSu26mGYW2FONzZQ8tkfxk23E/view?usp=drivesdk

[Mjw21a]

Another quick question, I've been trying to train my Logitech Harmony One to work with the Tortuga with no success currently. Is the Tortuga currently locked to the Apple Remote it shipped with? If so is there a way for me to remove this lock?

Cheers

Matt

EDIT: Never mind. I was being lazy. Found this: https://www.audiocircle.com/index.php?topic=174645.0

EDIT2: Just replicated the volume lag with the remote though that’s a one off so far. Matt not happen again.

[tortugaranger]

Here’s a short video of the volume knob issue Morten. In my mind definitely a firmware issue rather than hardware based on the units observed behaviour. I.e. The volume knob will wake it up but there's a delay before it will accept volume change. The bug doesn't seem to affect control via the remote thankfully.

https://drive.google.com/file/d/1crMqpzeiSu26mGYW2FONzZQ8tkfxk23E/view?usp=drivesdk

Thanks for the video. Videos like this can be very helpful in sorting through odd behaviors. This video shows that the display timeout feature has been enabled where the display turns off after a defined number of seconds. Turning the volume knob turns the display back on and resets the display timeout timer. I discovered that the user adjustable timeout value was not being properly saved which caused a brief delay in responding to further control inputs. Since correcting this I've not been able to reproduce the delay behavior so I'm thinking this bug will be resolved in the next firmware update.

[Mjw21a]

Excellent, thanks Morten. I look forward to the next update. Things have improved more with further burn in of the active components with sonics improving to a point where things are now sounding outright magical. I’m now extremely happy with the unit. Particularly with a fix for the volume delay on the way.

[Mjw21a]

Well it seems the Sonic Imagery 994Enh-Ticha was too big to fit so I’ve ordered a DIP8 socket extender. I’ll try it once recieved.

I did have some Sparkos SS3602 discrete OPAMPS on hand and tried them for a day. Overall they were too clean and sounded unnatural. The TL072 that is standard in the unit is noticeably better so it’s back in place. I kind of wish I still had a Burson V5i-D on hand. They’rea semi discrete FET based OPAMP and that could work rather well. I’m not really a fan of the Burson V6 finding the Vivid and Classic to be polar opposite of each other. Not really that well balanced.

Anyway Even if the Sonic Imagery isn’t an improvement it’s no big deal when things already sound this good. 

[tortugaranger]

Well it seems the Sonic Imagery 994Enh-Ticha was too big to fit so I’ve ordered a DIP8 socket extender. I’ll try it once recieved.

I did have some Sparkos SS3602 discrete OPAMPS on hand and tried them for a day. Overall they were too clean and sounded unnatural. The TL072 that is standard in the unit is noticeably better so it’s back in place. I kind of wish I still had a Burson V5i-D on hand. They’rea semi discrete FET based OPAMP and that could work rather well. I’m not really a fan of the Burson V6 finding the Vivid and Classic to be polar opposite of each other. Not really that well balanced.

Anyway Even if the Sonic Imagery isn’t an improvement it’s no big deal when things already sound this good. 

I tried numerous alternatives to the TL072 but kept coming back to it. Even very pricey well regarded audio-centric op amps did not clearly outperform the TL072 which is considered a general purpose low-noise JFET op amp that started life all the way back in 1978. Curious to get your take on any of the discrete opamps, none of which Iv'e tried yet in this application.

[Mjw21a]

Yes, the Sparkos was a bit of a let down though to be fair I’ve never much liked their sound. The next discrete I’ll try is the Sonic Imagery 994Enh-Ticha, maybe a SX45B as well though then I’ll call it a day. A fair chance the TL072 will be the victor.