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Looking for ideas on Lyra Delos - muddy middle

I realize I'm opening up any number of Pandora's boxes here, but given that the cartridge designer is a regular visitor/contributor, I'm hoping to get some great feedback in addition to the great feedback I'll be getting from all of you.

Here's the dilemma - I recently bought a used Lyra Delos (claimed to have less than 400 hours on it) cartridge to mount on my current rig.  Details on that setup later in this post.  After some serious VTA adjustment/validation, Azimuth adjustment/validation and verifying the rake angle is accurate, I get what I think is the best sound I can get out of the setup of the cartridge. And, with 200ohms loading, I've sanded off the highs while keeping the lows and everything there is in check - detailed and musical.  Yet on a number of recordings (Rock mostly, but some jazz and psych with large transient swings or lots of instrumentation in the moment) the 'music in the middle' sounds muddy and congested especially on faster passages - almost smearing like I'd expect on the highs except the highs (for the most part) are detailed and cymbal decay, for example sounds right and not smeared or slushy.

Great channel separation, great soundstage, just a clogged middle.  Am I missing something obvious?  I feel like I've been back and forth and over and over and I'm just not finding anything.  I haven't gone back to my previous cartridge to check if it's something else in the signal path, but that would be the next thing if there isn't anything that comes from this discussion.  And, of course, if I go back and find that it's not the case with the old cartridge, then what?

My reference recordings to test are:

Arne Domerus - Jazz at the Pawnshop (German Pressing)
Beach Boys - Pet Sounds (Mono Reissue)
Dead Can Dance - Into the Labyrinth (MoFi Master Reecording)
Deep Purple - The Book of Taliesyn (EMI/Harvest)

and yes, the records are cleaned before playing.  


My rig:

Table: Thorens TD-124 Mk I with Mk II upgraded motor supports, custom dual-tonearm plinth
Cartridge: Lyra Delos (used, but no rebuild to my knowledge) w/Boron Cantilever/Microridge stylus
Old Reference Cartridge: ParadoxPulse modified Denon103R w/Sapphire cantilever/Microridge stylus

Tonearm: Esoteric Sound S320 Mk II
*Type: Static balance, tubular, S-shaped, with removable headshell
*Effective Length: 9.02 inches (229 mm)
*Effective Mass: 13.4 Grams
*Resonance: 8.5 Hz
*Spindle to Pivot Distance: 8.43inches (214 mm)
*Mounting Hole: 1-3/16 inches
*Arm mounting pillar diameter: 0.703 inches
*Overhang: 0.59 inches (15 mm)
*Offset Angle: 22 degrees
*Tracking Error: +1.9/ -1.1 degrees
*Bearings: Steel ball bearings
*Material: Aluminum, Magnesium
*Dampening: Rubber
*Finish: Matte Black
*Horizontal and Vertical Sensitivity: 20 mg
*Height Adjustment: 1.5 to 2.4 inches (38 - 60 mm)
*Tracking Force Calibration Range: 0 to 3 gm (for more force, turn
  weight past "0")
*Counterweight: 140 gms
*Anti Skating Range: 0 to 3 gm
*Cartridge Weight Range: 4.0 to 12 gms
*Headshell: Magnesium with oxygen-free copper Litz wire, adjustable azimuth

 Phono Preamp - Paradox Pulse Phono 70 w/200ohm loading

Headphone Amp - SRM-007I w/Mullard/Brimar tubes (6gc7)
Headphones - Stax Lambda Nova Signature (Serial - S00966)


The only thing I can think of is to further tweak cartridge loading, but that may cross the line of diminishing returns.

Thoughts?  

Thank you in advance for any advice you can give.
dducat
mulveling's avatar
mulveling
2,451 posts
 
I would definitely check the rest of that signal path. I’ve run Stax and vinyl and it can be simply sublime, but Stax amps push out a ton of gain (almost as much as an MC phono stage, 54 - 60 dB typical), at very high voltage rails (+/-300V and higher), and the higher performance models (usually from the Stax "DIY" community) can push out a ton of heat too. In short, you gotta keep an eye on them. If your amp has push/pull balance control and DC offset trim pots, learn to check/adjust them. Keep a spare set of fresh tubes on hand - check/suspect the ones you have now.

If you had the 007 (or even 009) headphones I’d say that a Stax 007 amp isn’t going to be powerful enough to drive them to higher volumes without congestion (not unlike what you describe), but the Lambdas are generally much easier to drive than Omega series.

Also maybe think about whether your table setup & phono stage may be sending excess subsonic energy to the Stax amp, possibly overloading it?
dducat's avatar
dducat OP
40 posts
 
@mulveling Thanks for your thoughts.

I will certainly re-bias the Stax just as a matter of practice.  I do have some other tubes to roll (I was going to do that outside of this issue, anyway) but I don't want to change too many variables at once.  I will probably do that too however, just because I want to see how they sound, regardless (and they're NOS RCA Black Plates, NOS Raytheon Black Plates and NOS Sylvania US-made).

Right now, I'm only listening through the Stax (e.g. no other amp in play).  I do appreciate the concerns about extra gain in the signal path.  That had crossed my mind as the Delos puts out more than the Denon does, but I didn't think it was that much to be an issue (..6mV vs..2mV).  Given the phono stage has no gain controls, cartridge loading may be the actual issue (assuming that everything else checks out) in the end.
daveyf's avatar
daveyf
3,115 posts
 
@dducat  0.2mv vs 0.6v is actually a fairly considerable difference in gain. The phono stage should be working a lot less with your Lyra..and this should actually lead to less noise than your other cartridge...not more.
One other thing to consider, and this is mentioned in the Lyra instructions, is the phono cable capacitance. This can have a factor on the load at the cartridge, and also on the overall SQ, although I wouldn't have thought that it would result in the problems that you are relating.
Do get back to us once you have tried the higher loading.
mulveling's avatar
mulveling
2,451 posts
 
@daveyf brings up another good point. 70dB of active JFET gain is a LOT of gain for a cartridge with a healthy 0.6mV of output. You could be cutting it close to the stage's overload margins? Paradox seems like a small shop, and it's possible the focused on super-optimizing the phono stage for their own 0.3mV cartridge (also their website is riddled with grammar errors and misspellings; just a bit concerning when attention to detail is the name of the game in vinyl). Really I'd both checkup the Stax amp and try another phono stage, with something in the range of say 54dB - 62dB of gain, before I suspected the used Lyra cartridge at fault. But then I'm a junkie with multiple of every component on hand :P 
dducat's avatar
dducat OP
40 posts
 
@mulveling Yes, it’s a small shop, but the owner has been incredible in terms of service. Decware, for example here in IL is also a small shop but world-renown for making quality gear. But, your point is valid in that I might be right on the edge of overload. Unfortunately, my other stage and transformer is in use by my 20-year old who I hooked into the habit.
So, I don’t have much I can do there short of buying another stage and I’m not necessarily ready to do that just yet.

@daveyf I am currently running 750ohms and it seems to have made a difference in the middle. It also seems to have narrowed the soundstage a bit. I’m going to run it a bit and see how it goes. It seems that cartridge loading may be the solution and other tweaks (I haven’t rebiased yet) will help beyond that.

Not surprisingly, every little tweak has helped this configuration. I knew it was going to be more challenging going into it, but admittedly, I didn’t think it would be this challenging. But, in fairness, the Denon103R setup is pretty darn easy.
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