LDR300x.V3 Preamp Tour

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tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #20 on: 11 Oct 2020, 02:12 pm »

** Updated **

Here's the tour sequence lineup. We start off waaaay  west in Hawaii, then Washington, California, Arizona, back to the east coast in New Jersey, then North Carolina and finally full circle to Florida. The Midwest is missing - where'd you guys go?

After much hurry up and wait the tour kicks off this week. We've been doing a ton of work the last 2-3 weeks refining the firmware based mostly on initial feedback. glynnw dropped out of the tour because he went ahead and bought one instead...no patience ;)

Still have room to add a few as we move along.

Please remember your commitment to keep the tour unit for no more than one week. Which means if you receive it on a Monday you ship it on to the next person no later than the following Monday.

Enjoy and look forward to your feedback/reviews.

1) uncola - HI
2) MttBsh - WA
3) Delta77 - CA
4) Emiel - AZ
5) Bob2 - MI
6) sruffle - NJ
7) krustykat - NC
8') GentleBender - FL
9) jriggy - ??
« Last Edit: 11 Oct 2020, 09:24 pm by tortugaranger »

jriggy

Re: LDR300x.V3 Preamp Tour
« Reply #21 on: 11 Oct 2020, 02:57 pm »
You’re calling for me now here in the mid-west! And I was thinking about asking to join after seeing the tour recently.

Have always been interested in trying one of your offerings since I do like DAC direct to amp for some listening, so I thought I’d also probably enjoy a passive.

Bob2

Re: LDR300x.V3 Preamp Tour
« Reply #22 on: 11 Oct 2020, 04:04 pm »
I'm interested. 49286.

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #23 on: 11 Oct 2020, 09:20 pm »
You’re calling for me now here in the mid-west! And I was thinking about asking to join after seeing the tour recently.

Have always been interested in trying one of your offerings since I do like DAC direct to amp for some listening, so I thought I’d also probably enjoy a passive.


I'll add you in.
Please send PM me your full name, address, phone # & email address.

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #24 on: 11 Oct 2020, 09:20 pm »
I'm interested. 49286.



I'll add you in.
Please send PM me your full name, address, phone # & email address.

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #25 on: 12 Oct 2020, 02:57 pm »
Well, looks like we filled in that Midwestern hole with 2 additions from Indiana and Michigan.

1) uncola - HI
2) MttBsh - WA
3) Delta77 - CA
4) Emiel - AZ
5) jriggy - IN
6) Bob2 - MI
7) sruffle - NJ
8') krustykat - NC
9) GentleBender - FL

uncola

Re: LDR300x.V3 Preamp Tour
« Reply #26 on: 20 Oct 2020, 08:49 pm »
 usps sent me a note saying it's being delivered TODAY  :D
edit:  oops, something else is being delivered today.  the Tortuga preamp is being SHIPPED today
« Last Edit: 20 Oct 2020, 11:09 pm by uncola »

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #27 on: 21 Oct 2020, 06:36 pm »
usps sent me a note saying it's being delivered TODAY  :D
edit:  oops, something else is being delivered today.  the Tortuga preamp is being SHIPPED today

Yes, the tour unit has finally left the building and is on its way to Hawaii so we are off and running on this tour at last.

We've been doing a LOT of updating, improving and bug killing since the release of the V3 a few weeks back and feel the LDR300x.V3 is already fairly far up the maturation curve.

We ran into 2 problems worth noting; random lock-ups and sonic artifacts during volume change. Both have now been resolved.

It took a while to solve the random lock-ups but we finally got that taken care of. We only recently became aware of the sonic artifacts (soft putt-putt-putt-putt motorboating sound usually associated with unstable op amps - not the case here). The sonic artifacts were only present during volume change or when the screensaver was running (with the swimming turtle). The artifacts were from high frequency serial data bursts being sent to the the OLED display anytime the display was being updated. We didn't notice these artifacts during development for the simple reason that they were very faint - we had to put our ear next to the speaker/driver to notice. After some analysis we decided to stop having the turtle swim continuously when the screensaver is active. We also made changes to the serial data transmission firmware that substantially quieted these transmissions. In our view these sonic artifacts are now essentially undetectable (with normal ears) and, most importantly, are NEVER present at all during normal listening.

We hope you all enjoy the tour experience and we look forward to your questions, comments and suggestions.

Cheers,
Morten

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #28 on: 23 Oct 2020, 05:39 pm »
Dear Tour Participants,

I thought I'd elaborate on the possible ways you can evaluate the LDR300x.V3 that can make for a more interesting experience.

Active vs. Passive - The tour unit comes configured as an active preamp. However, you can remove the top half of the enclosure in order to access jumpers JPL and JPR located on the Interface Board near the right side of the rear panel. By moving the jumpers on on JPL and JPR from the "A" position to the "P" position you effectively bypass the active gain/buffer board and can operate the preamp as a passive unit.

Active - Unity Gain or +6 dB - The active tour unit is set to unity (1.0X) gain hence there's no actual amplification of the audio signal within the preamp. The 2 unity gain modules can be swapped out for a pair of +6 dB gain modules provided with the tour unit. Please be aware that the gain modules must be aligned properly such that the white dot on the plug-in module is on the same side of the 4 pin module header as the white dot on the board.  Sound complicated but it will make more sense when you see it.

LDR vs Discrete Attenuation - The tour unit comes set up with an LDR attenuation module installed. This module can be removed and replaced with a discrete attenuation module that uses thin film resistors only. The LDR module has 100 steps of attenuation while the Discrete module has 127 steps of attenuation. Arguably a bit overkill at 127 steps but it was either that or 63 steps which, while plenty granular, would be considerably less than the 100 steps with the LDR. When swapping theses modules, please only do so by first powering down the preamp and either disconnecting it from your amp or making sure your amp is turned off. Common sense stuff.

When done with the tour unit and before packing it up and shipping it onwards, please put it back to its original default state of active, unity gain modules and LDR attenuation module.

Thanks and I hope you enjoy the tour.

Cheers,
Morten

P.S.  To remove the top half of the preamp case, remove only the top 2 corner socket screws on both the front and the rear panels. Leave the bottom screws installed. Then gently rock/pry the top half shell up and off the unit.



GentleBender

Re: LDR300x.V3 Preamp Tour
« Reply #29 on: Yesterday at 07:11 pm »
Can you pin this post to the top of the page? This info will be really helpful for those on the tour. I look forward to seeing what people say about the different settings before I get my hands on it.

tortugaranger

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Re: LDR300x.V3 Preamp Tour
« Reply #30 on: Yesterday at 07:28 pm »
Can you pin this post to the top of the page? This info will be really helpful for those on the tour. I look forward to seeing what people say about the different settings before I get my hands on it.

I would if I could figure out how to do it. I can make topics stick to the top but don't see a way to make a post be sticky within a topic. If someone knows if there's a why please enlighten.


uncola

Re: LDR300x.V3 Preamp Tour
« Reply #31 on: Today at 01:25 pm »
the eagle has landed!  Just got home from work, unpacked it and took photos.  Will plug it in tomorrow :)
first reaction:  the discrete resistor attenuation module is to tiny!  I'm used to it taking up half the space inside a preamp or integrated amp with those relays and huge space taken up by all the resistors.