Tour - LDR300.V25 Buffered (Active) Preamp

0 Members and 1 Guest are viewing this topic. Read 8459 times.

tortugaranger

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Full Member
  • Posts: 319
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Full Member
  • Posts: 1514
  • Came for the value, stayed for the drama
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

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
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

  • Full Member
  • Posts: 1514
  • Came for the value, stayed for the drama
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #30 on: 21 Sep 2018, 09:45 pm »
Got it. Sounds fab! Bass is very authoritative. More to come. Stay tuned.    8)

Rusty Jefferson

  • Full Member
  • Posts: 319
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #31 on: 21 Sep 2018, 11:56 pm »
Will this be the comment/review thread also?

tortugaranger

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #32 on: 22 Sep 2018, 12:28 pm »
Will this be the comment/review thread also?


Yes.

WC

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #33 on: 22 Sep 2018, 10:30 pm »
Buffer board is almost as big as preamp board. Bigger than I thought. I don't have that much extra room in my box.

tortugaranger

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #34 on: 26 Sep 2018, 08:25 pm »
** Important Message For Tour Group Participants **

Just prior to sending out the tour LDR300 preamp we decided to wire the dual outputs in mixed mode with 1 set of outputs (outer most pair) being buffered and 2nd set of outputs (inner most pair) being passive. Easy enough to do. However, in doing so we overlooked the fact that the buffer would backfeed a brief voltage spike on to the passive output when the buffer gets turned on. The result is a harsh audible POP when the preamp is turned on IF you have it hooked to the passive outputs and IF you have your amp(s) turned on. After looking into this we've determined that there's nothing we can  do in the firmware to fix this. To fix this would require a modest hardware change in the design of the V25 preamp controller board. After considering this we've decided NOT to make that change to the V25 design and to only wire the LD300's outputs to the buffered output going forward. Not unreasonable given that the LDR300 is a buffered/active preamp and was never intended to be a passive preamp.

In designing the solid state buffer for the LDR300 it's fair to say that a LOT of work went into the protection circuit/logic/controls of the buffer to avoid bumps and pops during power turn-on and turn-off. Rightly so. However, we never really looked at what the buffer side might be doing to the unbuffered passive output for the simple reason we weren't focused on that - the LDR300 was to be operated as a buffered preamp, not a passive preamp.

You can still use the tour LDR300 in passive mode by connecting to the inside set of outputs but beware that you'll get a nice big pop out of your speakers if you have your amps on when you turn on the preamp. There are no pops when connected to the outside pair of buffered outputs.

A few of the early production LDR300.V25's already shipped were wired similarly in dual mode. We are discontinuing that. Going forward both outputs will be buffered.

Rusty Jefferson

  • Full Member
  • Posts: 319
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #35 on: 27 Sep 2018, 03:25 am »
Thank you for the heads up.  I'll only use the buffered outputs.  I never know when the power may go off/on in my neighborhood.

If the outputs aren't labeled on the tour model (I think you mentioned they wouldn't be), would you mind posting a photo of the rear panel indicating which output is which, please?

tortugaranger

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #36 on: 27 Sep 2018, 03:12 pm »
Thank you for the heads up.  I'll only use the buffered outputs.  I never know when the power may go off/on in my neighborhood.

If the outputs aren't labeled on the tour model (I think you mentioned they wouldn't be), would you mind posting a photo of the rear panel indicating which output is which, please?

Use the outer most pair of output jacks. By "outer most" I mean the output jacks at the outer edge of the rear panel. Or....the left most pair of jacks labeled "Out" when viewing the rear panel from the rear.

To be clear, there's no harm in using the other passive output jacks just be mindful of having your amps turned off (or the preamp output disconnected) when you turn on the preamp.

tortugaranger

  • Facilitator
  • Posts: 1330
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #37 on: 28 Sep 2018, 02:22 pm »
Konut will be shipping the tour unit on to SFDude on Monday.

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)

SFDude

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #38 on: 1 Oct 2018, 03:52 am »
Konut will be shipping the tour unit on to SFDude on Monday.

1) konut (WA)
2) SFDude (WA)

It's Monday, Monday,
Gotta get down on Monday. :D

konut

  • Full Member
  • Posts: 1514
  • Came for the value, stayed for the drama
Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #39 on: 1 Oct 2018, 09:40 pm »
The tour unit has been sent to SFDude. A few short thoughts today before I submit a more thorough review later this week.

I highly recommend you familiarize yourself with the remote operation found here.

https://www.tortugaaudio.com/support/product-documentation/?section=oled-v25-control-menu

It was not intuitive for me.

The unit worked flawlessly with great precision. I was sad to see it go.