Tour - LDR300.V25 Buffered (Active) Preamp

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tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #20 on: 24 Aug 2018, 02:07 pm »
Dear Tour Participants,

A quick update on the tour. We are waiting on production boards at this point which should arrive next week in time for the formal release of the new LDR300.V25. Realistically it will take us another week to get units built and start shipping so figure 1st week of September for the tour unit to go out.

There's been a lot of last minute back and forth regarding which specific buffer output component we'd go with but fortunately that subsystem is on a small 4-pin plug-in board so making changes now or in the future will be relatively easy. It's quite amazing how much of a sonic impact changing the buffer transistor makes. It's been quite an eye opener.

For those of you participating in the tour, if you would be so kind, please PM me your contact info including full name, address, phone # and email.

I will sort the sequence of the tour once I have everyone's address. I'll try to minimize shipping distances/cost/time.

Thanks,  :thumb:
Morten

SFDude

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #21 on: 24 Aug 2018, 05:54 pm »
Sounds good. Looking forward to the tour!

-dave

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #22 on: 26 Aug 2018, 02:14 pm »
If you still have room I'd love to try this preamp on the tour. As with the the buffer tour, it's very generous of you to offer.


Will add you in. Thx for your interest.

Rusty Jefferson

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #23 on: 26 Aug 2018, 09:57 pm »
Will add you in. Thx for your interest.
Thank you, I appreciate the opportunity to demo it.

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #24 on: 27 Aug 2018, 05:27 pm »
Just a heads up to let the tour group all know that the dual outputs on the tour LDR300 will be wired so that one set of outputs are passive outputs while the second pair of outputs are buffered outputs. There's no bypass or mode switch per say. You can try both output signals which will give you an interesting comparison of the passive vs buffered sound. Look forward to hearing all your thoughts on the differences ....or if you can tell the difference!

The output types won't be labeled !!

Cheers,
Morten  :thumb:

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #25 on: 10 Sep 2018, 01:36 pm »
Hi All,

I'm happy to report that the LDR300.V25 Buffered Preamp tour finally kicks off this week! Yippee!!

I've sorted the list based on location and the tour kicks off in Washington on the left coast where there's a group of participants. From Washington it goes to Colorado and then to the Midwest in Wisconsin and Ohio. Then on to Maryland and finally back to Florida.

I'm waiting on contact info from Ern Dog so there may well be some adjustments once I have his info.

I'll update this thread once the unit is finally shipped out later this week.

Thanks again for your participation. I look forward to your feedback.

Cheers,
Morten

1) MttBush (WA)
2) konut (WA)
3) SFDude (WA)
4) Tubeburner(WA)
5) ssglx (CO)
6) TJHUB (WI)
7) wirenut (OH)
8 ) rustyjefferson (MD)
9) audiogurujax (FL)
10) Ern Dog (??)
« Last Edit: 10 Sep 2018, 05:43 pm by tortugaranger »

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #26 on: 10 Sep 2018, 06:13 pm »
Fine tuning the tour sequence based on most recent inputs.
At this point I don't expect this sequence to change much if at all.
In terms of timing, figure on roughly 1 week each plus maybe a couple of additional days for shipping. 

1) konut (WA)
2) SFDude (WA)
3) Tubeburner(WA)
4) MttBush (WA)
5) Ern Dog (OR)
6) ssglx (CO)
7) TJHUB (WI)
8 ) wirenut (OH)
9 ) rustyjefferson (MD)
10) audiogurujax (FL)

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #27 on: 13 Sep 2018, 08:24 pm »
And we're off...

Konut the tour LDR300 is headed your way and should arrive by Tues/Wed next week.

A little info on the tour unit.

The tour LDR300 is a converted LDR3.V25. What that means is the LDR3 had been used here off and on for the past year and as such is not a brand new unit although it's been upgraded with our new OLED display. Consequently, the rear panel on the tour unit still says LDR3.V25 even though the internals have been modified to include the new SSB.V1 Rev A solid state buffer board which has been integrated with the V25 controller. Thus the only real difference between a production LDR300 and the tour LDR300 are purely cosmetic.

The tour LDR300 includes the optional upgrade to a Belleson SuperRegulator which has specs claiming 110 dB noise suppression compared to around 80 dB using the stock TL317 regulator. The tour LDR300 also includes the option upgrade to VCAP 3.3 uF OIMP output caps which are about as large a physical cap as will practically fit into the current buffer board. From very recent testing I've bumped up the input caps to 4.7 uF WIMA MKP polypropylene caps which are now the stock caps of choice until such time as we discover a better alternative.

The LDR300's buffer utilizes slightly more than 3,000 uF of power supply filtering which is arguably total overkill since it draws maybe a total of 25 milliamps of primary power. The filter caps are ELNA Silmic II silk capacitors which in my view are some of the best electrolytic audio capacitors available today. One of the goals for the LDR300 was to have as dead quiet an output as the unbuffered passive signal. Subjectively I think we accomplished that but I look forward to getting the opinion of others as they give it a try.

We spent way more time than I'd planned on trying out various makes/models of transistors in the buffer module. We listened to several MOSFET as well as JFETs. In the end it was no contest when we finally tried out the LSK170 JFET made by LinearSystems in California. It not only sounded the best but its noise specs are remarkably low. The buffer modules are plug-in so if we find something better down the road it would a simple matter of yanking the current modules out and plugging in new ones. 

One of the areas that I spent quite a bit of time futzing with is the power-up/turn-on/turn-off/power-down logic and protection. The goal was to avoid any noticeable power/turn on/off transient bump at the speakers. I'm confident we succeeded at this. One of the consequences is there's an extra long delay...sometimes upward of 20 seconds...from the time you plug power into the preamp, and subsequently turn it on after it boots up, before the preamp outputs connect to the buffer and goes live the first time. Assuming you keep power connected to the unit, then during subsequent normal turn on/off there's only a 10 second delay before the buffer unmutes. Buffer output isolation is done via LDRs and not relays. There are no relays in the signal path.  Note that if you abruptly remove power from the preamp before first turning if off normally, you'll probably see a very brief but non-violent in/out excursion in your woofer cone but absolutely no pops or bangs.

The tour LDR300 has dual outputs. The outermost (closest to edge of rear panel)  pair of outputs are the buffered outputs. The second inner pair of outputs carry the unbuffered passive preamp outputs. If you're curious how different (or similar!!)  the preamp sounds as a passive vs. buffered this can very easily be done by manually moving your interconnects between these 2 pairs of output jacks.

In keeping with our lean approach to paper manuals and such, you can find plenty of current info on the preamp controls in section 2.2 of our online documentation which can be found via the link below. The controls are fairly straightforward now that we've changed over to the menu driven OLED display.
https://www.tortugaaudio.com/support/product-documentation/?section=oled-v25-control-menu

Enjoy the LDR300. Give it a good workout. Thanks for participating. And let us all know what you think.

Cheers,
Morten

konut

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #28 on: 13 Sep 2018, 09:47 pm »
Thanks Morten. Looking forward to putting it through its paces.

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #29 on: 14 Sep 2018, 07:58 pm »

First production pics of the LDR300.V25. Internals with rear panel but without the front panel.



konut

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #30 on: Yesterday at 09:45 pm »
Got it. Sounds fab! Bass is very authoritative. More to come. Stay tuned.    8)

Rusty Jefferson

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #31 on: Yesterday at 11:56 pm »
Will this be the comment/review thread also?

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #32 on: Today at 12:28 pm »
Will this be the comment/review thread also?


Yes.