Tour - LDR300.V25 Buffered Preamp | Part II

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tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #60 on: 9 Nov 2018, 02:57 pm »
Tour unit is with Ern Dog this week with ssglx up next.

1) konut (WA)
2) SFDude (WA)
3) MttBush (WA)
4) Tubeburner(WA)

5) Ern Dog (OR)
6) ssglx (CO)
7) TJHUB (WI)
8 ) wirenut (OH)
9 ) rustyjefferson (MD)
10) audiogurujax (FL)

Standby
11) paul79
12) Naimnut

Naimnut

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #61 on: 10 Nov 2018, 03:57 pm »
Thanks for adding me to the standby list. BTW, I'm not in a hurry. The unit will replace a Naim 82/hicap in my system, between a Naim CD3.5 cd player and LP12/ittok/dynavector 17D3 into Linto and an Innersounds Electrostatic amplifier driving Quad ESL63s.

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #62 on: 13 Nov 2018, 10:30 pm »
Hi All,

This is a note to everyone on the LDR300 tour especially for Ern Dog and for those that have yet to get their turn in the barrel with this preamp. I will send you all a PM referring to this note just so you all get this.

It turns out we messed up a bit with the impedance setting for the tour unit and several other units we already shipped. In short, the effective impedance setting is too low notwithstanding that it's set at 20k. When placed in parallel with other fixed resistors within the buffer, the resulting lower impedance will most likely suck out some of the midrange rendering the sound a bit flat depending on your source.

I highly recommend setting the impedance of the tour unit up to say 70k.

Ern Dog, since you have the tour unit currently I suggest you do this immediately. Go down the menu list until you get to Imped. Select Imped. Then use the raise button to go to impedance setting #2 which is probably set to Off. Use the right/left buttons to increase the impedance level to 70. Then press Enter to start the cal cycle for the new impedance level. Once the cal cycle is done, run cal a second time by going down to the Cal menu, and then press the right button 3 times to start another Cal cycle at the 70k level. After the 2nd pass through cal at 70k it will be good to go.

I think you'll find the sound improved at the higher impedance setting.

Happy listening!
Morten

Ern Dog

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #63 on: 13 Nov 2018, 10:48 pm »
Will do. Thanks Morten

Tubeburner

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #64 on: 14 Nov 2018, 12:24 am »
I had the impedance set at 74,000 and it sounded good there.

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #65 on: 14 Nov 2018, 02:24 am »
I had the impedance set at 74,000 and it sounded good there.


Good! You're familiarity with the adjustable impedance feature proved helpful.

Ern Dog

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #66 on: 14 Nov 2018, 02:49 am »
I just reset the impedance to 70k and wow what a nice improvement!  It’s got more meat on the bones now. 

Tubeburner

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #67 on: 14 Nov 2018, 03:38 am »
You can add difference impedance values and switch impedance while listening. You might try some higher values in other positions. The impedance is a nice tweak and makes for a very enjoyable listening experience.

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #68 on: 14 Nov 2018, 02:42 pm »
I just reset the impedance to 70k and wow what a nice improvement!  It’s got more meat on the bones now.

Good news! Thanks for making the change and confirming the improvement. It's an interesting example of how too low a bridging impedance can suck the life out of the music. I hadn't thought that the adjustable impedance feature would be relevant to the LDR300 given that it's a buffered (active) preamp but it clearly made it possible to overcome this problem. In future builds we'll be omitting the resistors that pulled down the impedance such that the default 20k impedance setting should be more than adequate for excellent performance.

Cheers,
Morten :thumb:

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #69 on: 17 Nov 2018, 07:42 pm »
Hi All,

A brief housekeeping update on the tour.
Ern Dog will be sending the tour unit on to ssglx in Colorado next.
Wirenut has dropped out due to his system being unavailable. Paul79 from Oklahama will be taking his place.

1) konut (WA)
2) SFDude (WA)
3) MttBush (WA)
4) Tubeburner(WA)

5) Ern Dog (OR)
6) ssglx (CO)
7) TJHUB (WI)
8 ) wirenut (OH)
8 ) paul79 (OK)
9 ) rustyjefferson (MD)
10) audiogurujax (FL)

Standby
11) Naimnut

Ern Dog

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #70 on: 17 Nov 2018, 08:06 pm »
I thoroughly enjoyed my short time with this preamp.  Thanks Morten for setting this tour up for us.  I shipped the unit off to ssglx yesterday.  Here's my review:

Cons:
- Using the Apple remote was wreaking havoc on my Apple tv because controlling the preamp also controls the apple tv at the same time.
- The cheap wall wart didn't instill confidence
- Having to calibrate after making changes was a pain
- The wait time for a calibration was too long
- There is a learning curve to learn how to operate the unit but it didn't take long and was easy after learning.
- Requires careful system matching.  It wasn't a good match with my Border Patrol SET 8 wpc amp

Pros:
- I liked the balance control feature
- I liked the price of $1500
- The sound was excellent

I was off to a rough start because after setting it up I only could hear the right channel, but was able to recover after a reset and 3 calibrations.  But even after that the Rt side was louder than left and needed to adjust the balance to +20 left side to balance the sound.  After all that I thought the sound was nothing special.  I was not impressed with the mids- they sounded too sterile.  I couldn't wait to remove the preamp from my system .  I was impressed with the bass though- very full and deep and articulate.  Then Morten sent the message about adjusting the impedance to 70k.  This adjustment totally transformed the unit.  The mids and highs sounded organic and involving and the soundstage expanded.  There was more meat on the bone now.  I really enjoyed it and the bass was so powerful that I turned my subs off.  The sound I was hearing was Superb and it was easy to get lost in the music!

I bumped into system mis-matching with my 8 wpc SET amp.  There were many songs that I wanted to turn the volume up louder but I already had the volume maxed out at 100.  My system really requires a stout active preamp. 

Overall, I was very impressed with the sound of this unit.

Cheers,
Ernie

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #71 on: 17 Nov 2018, 10:18 pm »
I thoroughly enjoyed my short time with this preamp.  Thanks Morten for setting this tour up for us.  I shipped the unit off to ssglx yesterday.  Here's my review:

Thanks for participating and taking the time to post your review. I don't usual make detailed comments on a users review but I thought readers would benefit from some additional information and perspective.

Quote
Cons:
- Using the Apple remote was wreaking havoc on my Apple tv because controlling the preamp also controls the apple tv at the same time.

I personally have an Apple TV device that uses the same model of Apple remote. There's a straightforward but easily overlooked solution to this because Apple does not make it obvious. The Apple TV will respond to any Apple remote even though each Apple remote has a unique ID from 0 to 255 (256 possible IDs). To get the Apple TV to respond to only a specific remote (and ignore others) you have to pair the Apple TV with that remote. Once that's done the Apple TV will mostly ignore the Apple remote used by the Tortuga preamp.

Quote
Cons
- The cheap wall wart didn't instill confidence

I get that a lot. What's not obvious is the cheap wall wart is actually a linear regulated unit with surprisingly decent performance. It's only rated at 500 ma and is lightly loaded so we aren't asking much of it. More importantly the LDR300 utilizes a pricey Belleson SuperRegulator internally which has a -110 dB noise suppression spec which I would submit meets or beats most any low voltage and low current power supply out there. The unit is dead quiet (at least when running in our rigs here).

Quote
Cons
- Having to calibrate after making changes was a pain
- The wait time for a calibration was too long

Keep in mind that in normal use there's really not much point in changing the input impedance of the LDR300. As Ernie noted, we've pretty much determined that the LDR300 needs to run higher (75K) than our passive preamps which usually perform well at 20k.  It's an unusual feature altogether and is there solely to allow exploring performance optimization.

A typical calibration cycle takes 5-10 minutes. During that cycle it calibrates over 400 separate attenuation points which at 10 minutes is only 1.5 seconds per calibration step - fairly fast. But yes, 10 minutes is a PITA.

Quote
[size=78%]Con[/size]
- There is a learning curve to learn how to operate the unit but it didn't take long and was easy after learning.

The Tortuga preamps are light on conventional controls like knobs and switches and long on a visual menu driven control scheme. As Ernie noted, it's a relatively brief learning curve.

Quote
Con
- Requires careful system matching.  It wasn't a good match with my Border Patrol SET 8 wpc amp

Ernie ran out of volume headroom using the unity gain preamp with a relatively low wattage tube amp. This can happen especially if the low wattage tube amp is paired with less than super high efficiency speakers. Ironically we shared a room at RMAF 2 years in a row with Border Patrol and VOLTI with our unity gain passive preamp. At these shows we had no trouble shaking the room and annoying our neighbors with the same amp Ernie has but the speakers had an efficiency of 100 db!! The Border Patrol SET 8 watt amp is an excellent amp by the way. As it turns out Ernie's situation is probably THE ONLY matching issue for the LDR300. With higher power tube amps, and nearly every solid state amp, you'll likely have plenty of volume headroom.

Quote
Pros:
- I liked the balance control feature
- I liked the price of $1500
- The sound was excellent

I was off to a rough start because after setting it up I only could hear the right channel, but was able to recover after a reset and 3 calibrations.  But even after that the Rt side was louder than left and needed to adjust the balance to +20 left side to balance the sound.  After all that I thought the sound was nothing special.  I was not impressed with the mids- they sounded too sterile.  I couldn't wait to remove the preamp from my system .  I was impressed with the bass though- very full and deep and articulate.  Then Morten sent the message about adjusting the impedance to 70k.  This adjustment totally transformed the unit.  The mids and highs sounded organic and involving and the soundstage expanded.  There was more meat on the bone now.  I really enjoyed it and the bass was so powerful that I turned my subs off.  The sound I was hearing was Superb and it was easy to get lost in the music!

I bumped into system mis-matching with my 8 wpc SET amp.  There were many songs that I wanted to turn the volume up louder but I already had the volume maxed out at 100.  My system really requires a stout active preamp. 

Overall, I was very impressed with the sound of this unit.

Cheers,
Ernie

As Ernie says, the sound is indeed excellent and as high performance audio gear goes, the price is within reason.  :thumb:

MttBsh

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #72 on: 18 Nov 2018, 01:23 am »
"Keep in mind that in normal use there's really not much point in changing the input impedance of the LDR300. As Ernie noted, we've pretty much determined that the LDR300 needs to run higher (75K) than our passive preamps which usually perform well at 20k'

So Morten, I take it the impedance adjustment to 75K resulting in the "total transformation" that Ern Dog describes would apply only to the active stage which is input 3 on the LDE300.V25 we demo'd… is that correct? it wouldn't improve the sound through passive inputs 1 and 2?

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #73 on: 19 Nov 2018, 03:09 pm »
"Keep in mind that in normal use there's really not much point in changing the input impedance of the LDR300. As Ernie noted, we've pretty much determined that the LDR300 needs to run higher (75K) than our passive preamps which usually perform well at 20k'

So Morten, I take it the impedance adjustment to 75K resulting in the "total transformation" that Ern Dog describes would apply only to the active stage which is input 3 on the LDE300.V25 we demo'd… is that correct? it wouldn't improve the sound through passive inputs 1 and 2?

Not correct! Some key points of clarification...

First, the input impedance setting applies to all the inputs and not to any individual input. This is true of all Tortuga Audio preamps including the LDR300.

Secondly, the tour unit is unique in one regard insofar as the dual outputs are wired differently. The outer most output (nearest the left edge of rear panel as you face the rear panel) is the buffered output. The innermost output is passive only and bypasses the buffer. In production units both outputs are buffered and are identical (wired in parallel). 

FAIR WARNING - If you elect to connect to the passive output on the tour unit, do so only after the preamp has been powered up. Otherwise you'll get a rather loud pop when it powers up. This doesn't happen on the buffered output.

Third, the sound improvement from changing impedance from 20k to 75k is probably only relevant to the buffered output.

ssglx

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #74 on: 25 Nov 2018, 02:39 am »
Well, due to my shift schedule I only had time to listen for one evening before sending it on to TJHUB, but I do have a few observations to share.

I have currently two pre-amps, a Tortuga LDRx passive and an Audio Electronics (cary audio) AE-3, and I love them both.

The rest of my system consists of:
AppleTV (160 gb)
Musical Fidelity V-90 dac
Monarchy SM-70 Pro (24 w/ch)
Soliloquy 5.0i monitors, sitting on #2 Vibrapods (a wonderful match)

When I received the unit the balance was adjusted way to the left, and this was required to center the image. A recalibration didn't fix it, and it was worse at higher impedances. The fidelity seemed fine though so I carried on with the session.

I should state at the outset that I tried other passives (pot-in-a-box and a TVC) in my system before settling on the Tortuga . The Tortuga LDR to me seemed perfect in my system. Transparent, robust, clean, fleshy and exciting. I tried this buffered version really out of curiosity, and the thought that possibly I was missing something.

From this test I'd say my system doesn't need the buffer stage. I didn't identify much difference except that the buffered version might be a bit less transparent than my LDRx. Not surprising considering the additional circuitry.

I wholeheartedly recommend Tortuga preamps to everyone, but possibly try out the fully passive unit first before jumping to the more complex buffered version.

I did however like the new display and menu. Is that possibly a conversion I could do to my LDRx at home?

Chris

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #75 on: 27 Nov 2018, 02:59 pm »
Hi All,

I've been made aware that the LDR300 tour unit has developed a fairly severe channel imbalance so I've asked TJHUB to send the tour unit back to me for repair. I will correct the imbalance problem, update the firmware including setting the default input impedance to 75k and get it back to Terry ASAP so the tour can continue onwards and the LDR300 can shine.

A tour like this can stress the equipment due to multiple shipments/vibration etc so it can be an effective physical stress test in addition to being a great way to check out new gear and get feedback. Plus the tour unit was the last of the development prototype hardware so it had gone through a number of tweaks and changes before heading out on the tour all of which takes a toll.

As a general comment, I've spent the past few weeks with a production version of the LDR300 in my home rig and find that it's grown on me. The clarity, detail and dynamics are really quite good. Sure, I make and sell this gear so I'm naturally biased but I'm first and foremost an audio user and listener and the way I'm personally wired I could not (would not) promote something I don't get personal satisfaction from using myself.

Back soon!  :thumb:

1) konut (WA)
2) SFDude (WA)
3) MttBush (WA)
4) Tubeburner(WA)
5) Ern Dog (OR)
6) ssglx (CO)

7) TJHUB (WI)
8 ) wirenut (OH)
8 ) paul79 (OK)
9 ) rustyjefferson (MD)
10) audiogurujax (FL)

Standby
11) Naimnut

tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #76 on: 6 Dec 2018, 09:00 pm »
Hi All,

The tour unit arrived back in the shop today for a quick diagnostic and tuneup. As you you may recall the tour preamp developed a significant channel imbalance. That turned out to a bad connection on one of the JFET output modules which we then swapped out and that took care of the problem. Also gave the unit a firmware update which forced the default #1 impedance setting to be 75k going forward. Did a 30 minute listening test and I have to say travel suits this preamp because it's sounding better as the miles pile up.

The tour unit uses the RevA buffer board. We've already updated that board design with the RevB version which does away with the plug-in output buffer module. It may not be as flexible but the RevB will be more reliable.

The tour unit will be back out on the road tomorrow ready, willing and able.

Back on the road again!  :thumb:
Morten
____________________

Below is the updated  tour status. The unit is heading for TJHUB in Wisconsin next. We've had a dropout and an addition so we have 4 to go.

1) konut (WA)
2) SFDude (WA)
3) MttBush (WA)
4) Tubeburner(WA)
5) Ern Dog (OR)
6) ssglx (CO)

7) TJHUB (WI)
8 ) paul79 (OK)
9) Naimnut
10) audiogurujax (FL)
« Last Edit: 7 Dec 2018, 02:42 pm by tortugaranger »

paul79

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #77 on: 10 Dec 2018, 10:50 pm »
Thank you for the update. I am excited!

TJHUB

Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #78 on: 11 Dec 2018, 12:38 am »
Morten:  I wanted to let you know the tour unit arrived today and seems to be functionally perfect.  My intention was to listen until Wednesday or Thursday and ship it off to the next participant.  I’m sorry to say that is now not going to happen.  Based on the complexity of the changes I’m hearing, I’m going to keep it for the full week I’m allowed.  The differences in sound are interesting. 

One thing I’m struggling with is more bass than I’d like.  FYI, I’m VERY picky about sound (bass being very critical), and what I had prior to installing the LDR300 was as close to perfect as I’ve ever had.  The bass still has decent definition, but sounds too heavy.  So I’m wondering if you might suggest trying a different impedance setting?  I run 5k or 10k on my LDR3v2.  I don’t want to make changes without advise as this is a slightly different animal.


tortugaranger

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Re: Tour - LDR300.V25 Buffered (Active) Preamp
« Reply #79 on: 11 Dec 2018, 04:35 am »
Morten:  I wanted to let you know the tour unit arrived today and seems to be functionally perfect.  My intention was to listen until Wednesday or Thursday and ship it off to the next participant.  I’m sorry to say that is now not going to happen.  Based on the complexity of the changes I’m hearing, I’m going to keep it for the full week I’m allowed.  The differences in sound are interesting. 

One thing I’m struggling with is more bass than I’d like.  FYI, I’m VERY picky about sound (bass being very critical), and what I had prior to installing the LDR300 was as close to perfect as I’ve ever had.  The bass still has decent definition, but sounds too heavy.  So I’m wondering if you might suggest trying a different impedance setting?  I run 5k or 10k on my LDR3v2.  I don’t want to make changes without advise as this is a slightly different animal.


Our LDR preamps have always had strong bass but can't say I've noticed the LDR300 being any different in that regards but not surprising that performance may differ depending on synergies with each system. I think it's highly unlikely that changing the impedance will alter this. Unlike the LDR3.V2/V25 passives, the LDR300 will suffer from lowering the impedance down into the 5-10k range and will likely lose a tremendous amount of midrange if you go that low. This was the case at the earlier default 20k. At the now default 75k the LDR300 really opens up. You're no doubt noticing the differences between the LDR3 passive and the LDR300 buffer/active. On the one hand they're very similar yet very different. See if it doesn't grow on ya. Enjoy!