AudioCircle
Industry Circles => Tortuga Audio => Topic started by: tortugaranger on 4 Nov 2014, 03:11 pm
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We're in the planning stage of a complete DIY LDR Preamp Kit that will include a LDR3x.V2 preamp controller board. The kit will only be for single-ended RCA.
If you're interested in such a product, please leave a comment or question here or drop me a PM. Now is the time to pipe up with your suggestions or "wish list" while the design is still fluid.
The kit will be comprehensive and include the following:
* LDR3x.V2 (V2.1) board fully populated & tested
* aluminum enclosure including black powder-coated extruded alum uni-body and black or clear anodized front/rear panels - approx 6.5" wide x 2.5" tall by 8" deep
* 3 RCA inputs, 2 RCA outputs
* single display module
* 3 input relay board with parts - solder it yourself
* encoder with knob
* external wall-wart switching power supply
* silver coated stranded copper wire - enough to hook everything up.
* ribbon cable connectors as needed
* screws etc. as needed
You'll need to supply your own solder, iron, tools etc.
Cheers, :thumb:
Morten
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Hi
There is a USB CABLE included in the kit.
1 – USB cable for connecting between the LDR3x board and the rear panel
But there is no any USB port on the rear panel. Why?
:D
DAVE
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Hi
There is a USB CABLE included in the kit.
1 – USB cable for connecting between the LDR3x board and the rear panel
But there is no any USB port on the rear panel. Why?
:D
DAVE
Thanks for scrutinizing the kit parts list. No, really, we intend for that list to be comprehensive and complete so requests for clarification are welcome.
The answer is this particular USB cable has a 5 pin socket on one end to connect to the board and the other end has an integral USB port that attaches to the rear panel with 2 screws. :thumb:
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Thanks for scrutinizing the kit parts list. No, really, we intend for that list to be comprehensive and complete so requests for clarification are welcome.
The answer is this particular USB cable has a 5 pin socket on one end to connect to the board and the other end has an integral USB port that attaches to the rear panel with 2 screws. :thumb:
Do you sell USB cable separately?
:)
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Do you sell USB cable separately?
:)
Since several people have asked about this I will add it to our store. At $15 it's not cheap as 1 foot cables go but it serves the dual purpose of an internal board-to-panel connector plus as a robust type A USB port.
Here's the link to our website: http://www.tortugaaudio.com/product/usb-cable-port/ (http://www.tortugaaudio.com/product/usb-cable-port/)
Cheers,
Morten
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Hello Morten,
Would you consider offering a balanced kit that doesn't include an enclosure?
Thanks,
Sten
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Hello Morten,
Would you consider offering a balanced kit that doesn't include an enclosure?
Thanks,
Sten
Hi Sten,
A kit without enclosure really boils down to a collection of our DIY parts that you'd need for a balanced system. I have numerous customers who have gone this route even though we haven't yet proposed this as a true kit.
The list boils down to:
* 2 - LDR3x passive preamp controller board
* 2 - IO3 modules (assuming you want to be able to handle more than 1 input)
* 1 - DM1 display module (& perhaps a 2nd slave module) - not required but highly recommended
* 1 - Encoder module - not required but highly recommended
* 1 - PS12.5 power supply board - not required but you'll need your own alternative 12 VDC supply which can be as simple as a 12 VDC wallwart
* 1 - Apple Remote
* all the ribbon cables etc. for the above (which come with the items anyway)
As you can see from the list you quickly get into a list of options but if we were to offer an "everything but the box" kit it would include all these items.
It would be very helpful to understand what your view of a kit might include that isn't included in the above items.
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This is just what I was looking for. Thanks for clarifying Morten.
How many balanced and/or RCA inputs and outputs are possible with this setup?
If it supports both balanced and RCA outputs, are they both active at the same time?
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This is just what I was looking for. Thanks for clarifying Morten.
How many balanced and/or RCA inputs and outputs are possible with this setup?
If it supports both balanced and RCA outputs, are they both active at the same time?
The LDR3x can switch between 3 inputs. However, if these 3 switching signals are used with a 3 digit binary decoder you can switch up to 8 inputs. We currently only offer a 3 input relay switching board. A pair of relay switching boards are needed for balanced input. You can mix XLR or RCA inputs anyway you want but in my view since you're investing in a balanced preamp I suggest 1 RCA and 2 XLR. These are exclusive inputs. You only switch one input (RCA or XLR) at a time.
With mixed RCA/XLR it gets a bit messy. The RCA output while connected to a balanced input will be 6 dB lower in output than the balanced output since you're only taking one leg of the balanced signal for the RCA output. If you want an RCA input to be available as a balanced output, you'll need to run the RCA input through a transformer to convert it to a balanced signal before attenuating it and passing it out the XLR output. Clear as mud? Like I said, a bit messy.
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Hello again Morten,
I'll likely place an order for a standard preamp kit in the next couple of days and have a quick question for you.
The available upgrades for the kit lists a 2nd display and Cardas RCA jacks. The 2nd display has a nice discount from retail, however the Cardas jacks appear to be more expensive than if purchased separately. By my math the 5 pairs of jacks should be around $124, but the upgrade price is listed as $199. Could you please clarify when you get a chance?
Thanks, and Happy New Year.
-Sten
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Hello again Morten,
I'll likely place an order for a standard preamp kit in the next couple of days and have a quick question for you.
The available upgrades for the kit lists a 2nd display and Cardas RCA jacks. The 2nd display has a nice discount from retail, however the Cardas jacks appear to be more expensive than if purchased separately. By my math the 5 pairs of jacks should be around $124, but the upgrade price is listed as $199. Could you please clarify when you get a chance?
Thanks, and Happy New Year.
-Sten
Hi Sten,
Thanks for your note and for pointing out the pricing issue with the Cardas upgrade. The upgrade price was supposed to be $99 but it was mistakenly entered at $199. Thanks to your note it's now been corrected.
Best, :thumb:
Morten
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Morten,
Would you please explain the adjustable input impedance ( 1K to 100K ) and how that changes the chart below found on your site?
(http://www.audiocircle.com/image.php?id=113364)
I ask the question, because ultimately I'd like to know how the LDR3.V2 Passive Preamp would pair with my Odyssey Audio Khartago mono block amps. The amps have an input impedance of 22K Ohms. From what I understand, we want at least a 10X ratio of amplifier input impedance to preamp output impedance.
Thanks,
Gregg
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The key metric is the impedance "bridging" ratio which is the effective parallel impedance of the preamp/amp divided by the source output impedance. Usually a 50:1 or higher ratio is reliable indicator that things will work well with our passive preamps. This is general guidance and not some hard and fast rule. A lot depends on how robust the output stage is in your source. If you have a strong source able to deliver current into lower impedances you'll be ok with lower bridging ratios.
The best way I know how to get my head around this topic is by running the numbers in a spreadsheet with different assumptions regarding source output impedance, preamp input impedance and amp input impedance.
I've uploaded an Excel spreadsheet that you can download from our website which includes a version of the graph shown below. Look for the "Impedance Spreadsheet" link on the right. http://www.tortugaaudio.com/downloads/ (http://www.tortugaaudio.com/downloads/)
Morten,
Would you please explain the adjustable input impedance ( 1K to 100K ) and how that changes the chart below found on your site?
(http://www.audiocircle.com/image.php?id=113364)
I ask the question, because ultimately I'd like to know how the LDR3.V2 Passive Preamp would pair with my Odyssey Audio Khartago mono block amps. The amps have an input impedance of 22K Ohms. From what I understand, we want at least a 10X ratio of amplifier input impedance to preamp output impedance.
Thanks,
Gregg
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Morten,
Thank you for the response. I'll review the information.
Gregg
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Thinking about getting an LDR passive preamp?
Want to keep the costs down?
Willing to go the DIY route?
But don't want to search high and low for all the parts plus enclosure?
Consider the LDR3.V2K Passive Preamp Kit - $695
http://www.tortugaaudio.com/product/ldr3-v2k-passive-preamp-kit/ (http://www.tortugaaudio.com/product/ldr3-v2k-passive-preamp-kit/)
(http://www.tortugaaudio.com/images/LDR3.V2K_Parts.jpg)
(http://www.tortugaaudio.com/images/LDR3.V2K_Parts_OverviewPic.jpg)
(http://www.tortugaaudio.com/images/LDR3.V2K_Parts_List.jpg)
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Very cool Morten! :thumb:
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Initial customer feedback on having fired up his LDR3.V2k. I did not know it at the time he purchased the kit that he was already using a stepped passive attenuator.
Right from the start I was quite impressed by the sound performance. The Tortuga passive preamp replaced a passive preamp in my system equiped with Elma switches and Shinko tantalum resistors for shunt and series resitors. The Shinkos were until now the best resistors in this role and I was suprised that they were easily surpassed by the LDRs. The unit is now breaking in.
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The biggest problem with our LDR3x.V2K kit is a lack of comprehensive and easy to follow instructions. We are taking steps to correct this. In a couple of weeks we have 2 whole days scheduled with a videographer. We plan to document via video every step in assembling and testing this kit. Once we have the raw footage it will still take some time to edit it down and do the voice over. It will ultimately be published as a youtube video. We'll update you more on this as we progress.
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Video filming day for the LDR3.V2K! Roll'em!
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Nice, Morton. Would like to buy within the year. How much for all the options?
Nick
PS Great idea re the videos
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Video filming day for the LDR3.V2K! Roll'em!
Now that is the way to do it! See 1, Do 1, Teach 1!
Best,
Anand.
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Got all the raw "footage" done. Now comes the editing and voice over work. We didn't even try to script the spoken part, just showed the assembly steps. I will do the voice overs once we've whittled down the footage. Will break the whole thing up into chapters and post them on our youtube page when done. Still a lot of work left to get this done.
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Is the video up yet?
I bought the full version and love it. I am considering buying a second as a kit.
Thanks!
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Is the video up yet?
I bought the full version and love it. I am considering buying a second as a kit.
Thanks!
We started on the editing process but have gotten sidetracked and also underestimated the amount of time it would take to do this and end up with a worthwhile end product. In the meanwhile we did make some progress on at least writing up a descriptive narrative (sans pic/video). Have that written up and posted up until the wiring process which we still need to finish. Our goal is to write up the wiring section this weekend. We have 10 pounds of projects in a 5 pound company.
What we have so far can be found here: http://www.tortugaaudio.com/documentation/#cat-7 (http://www.tortugaaudio.com/documentation/#cat-7)
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As an interim solution, we've posted a narrative set of assembly instructions for the preamp kits. As part of this we are also now supplying all pcb boards already fully assembled and tested so no more soldering of individual components into circuit boards. As such, the kits are largely an assembly process of already built, cut and drilled parts together with point to point wiring.
You can find the current set of assembly instructions here: http://www.tortugaaudio.com/documentation/#cat-7 (http://www.tortugaaudio.com/documentation/#cat-7)
Also, we've added options to the kit where you can choose your display color (blue is default) and also opt for the high performance autocal op amp. http://www.tortugaaudio.com/documentation/#cat-7 (http://www.tortugaaudio.com/documentation/#cat-7)
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Our passive preamp kit continues to lack a really good set of detailed assembly instructions. Despite repeated attempts to focus on getting this done, it's clear that unless I hire someone to do it simply will not get done.
As of yesterday, I've hired an outside person to execute this assembly instruction project. I anticipate it will take somewhere between 2-3 weeks to complete the work because the guy doing the work is also a student at a local college.
At the very least the assembly instructions will have numerous detailed step by step photos along with explanatory text.
The objective is to have assembly instructions that require zero knowledge about audio electronics etc. but the customer will still have to do some soldering of wires here and there.
More on this when we have it up and available on the website.
Cheers,
Morten
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We've updated the LDR3 kit to the LDR3.V25K with the new V25 board which sounds really great!! :D
The comprehensive updated kit is available for $749. More info can be found here: https://www.tortugaaudio.com/products/passive-preamp-kits/ldr3-v25k-passive-preamp-kit/ (https://www.tortugaaudio.com/products/passive-preamp-kits/ldr3-v25k-passive-preamp-kit/)
AND!!! we now have a fully developed set of instructions for the new kit with plenty of pics and even a point-to-point wiring/cable schedule. Kit overview and assembly instructions can be found in our new online Product Documentation for the kit right here:https://www.tortugaaudio.com/product=documentation/ldr3-v25k-preamp-kit/ (https://www.tortugaaudio.com/product=documentation/ldr3-v25k-preamp-kit/)
Check it out! Spread the word! :thumb:
(https://www.tortugaaudio.com/images/LDR3.V25_right_front_side_view.jpg)