Pass Labs umbilical cable

jackelsson

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Dec 1, 2013
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I have read quite a few positive comments about the umbilical cables from Revelation Audio and how they improve the sound of Pass preamps when being used between the power supply and the line stage instead of the cheap standard cable that Pass is supplying.

In principle I would be inclined to try them out with my Pass gear but if I understand it correctly Revelation Audio has more or less doubled the price of their DB-25 umbilical cable within the last two or three years for no obvious reason. Apart from the fact that I have a little personal concern about this rather steep price increase and the reasons that might be behind this, the resulting current sum total for the four umbilicals needed for my XP-30 and my two XP-25 is now more than I would be willing to pay.

So the question is whether there are DB-25 cable substitutes from other manufacturers, and if so whether anybody has tried them and might be able to share their experiance?
 

BlueFox

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Nov 8, 2013
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Apparently, Pass agrees with the RA cable making an improvement. The new XP-22 contains an aircraft grade connector and socket to connect the power supply to the pre, versus the throw away plastic DB-25.

My RA cable on my XP-20 made it into a much better pre. Unfortunately, my trade-in price for my XP-22 includes the RA cable, so I can't sell it.

I suspect RA realized there was a demand for these cables, so they raised the price. :)
 

ack

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At someone else's urging, I looked at that cable years ago and it wasn't spec'd well. Since the, they switched to mil-spec connectors and other changes, and that may explain the price increase. At the same time, someone else wrote here recently that Pass themselves tested with that cable, and it was wired incorrectly. See the XP-22 thread, I think.

I tamed my stock umbilical with ferrite beads, which goes to show that it will pick up noise. I am personally afraid to try that cable if it's not connected correctly, pin for pin.
 

Vtech2000

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Oct 1, 2018
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At someone else's urging, I looked at that cable years ago and it wasn't spec'd well. Since the, they switched to mil-spec connectors and other changes, and that may explain the price increase. At the same time, someone else wrote here recently that Pass themselves tested with that cable, and it was wired incorrectly. See the XP-22 thread, I think.

I tamed my stock umbilical with ferrite beads, which goes to show that it will pick up noise. I am personally afraid to try that cable if it's not connected correctly, pin for pin.

On the contrary:

Amphenol Mil. Spec. connectors have always been employed on the Revelation Audio Labs DB-25 cable. With all due respect, it is challenged that evidence or proof otherwise be provided, because it is simply not so.

Revelation Audio Labs has had ZERO (no) reports from the field that this cable was miswired or inoperative. Again, with all due respect, it is challenged that evidence or proof otherwise be provided, because it simply has not occurred.

If Pass Labs engineers indeed published that they themselves tested the Revelation Audio Labs cable with any Pass Labs equipment, it is respectfully requested that the reference or link to this please be provided for enlightenment of us all.
 

jackelsson

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Dec 1, 2013
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Well, even if there had been some quality upgrade at one point in the past I'm a bit mindful that suddenly asking twice the initial price might be more founded on revenue expectations than actual oncost for a new plug.

It's really a shame that with Pass now moving to another cable type it's rather unlikely that competition will suddenly turn up offering an upgrade path to the factory cable at a more reasonable price somewhere around the initial price point of the Revelation Audio umbilical.

Having said that, I saw that Vovox manufactures studio grade multipair cables with Sub-D 25 connectors on both ends, and they also customize cables if necessary. That might be an option worth trying.

https://www.vovox.ch/en/professional-audio/products/sonorus/multipair-cable/

Does anyone know the pin-out scheme in the original Pass umbilicals?
 

Evolusean

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Apr 21, 2014
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On the contrary:

Amphenol Mil. Spec. connectors have always been employed on the Revelation Audio Labs DB-25 cable. With all due respect, it is challenged that evidence or proof otherwise be provided, because it is simply not so.

Revelation Audio Labs has had ZERO (no) reports from the field that this cable was miswired or inoperative. Again, with all due respect, it is challenged that evidence or proof otherwise be provided, because it simply has not occurred.

If Pass Labs engineers indeed published that they themselves tested the Revelation Audio Labs cable with any Pass Labs equipment, it is respectfully requested that the reference or link to this please be provided for enlightenment of us all.

I'm in agreement with you on this.
I've had no issues with mine.
 

PeterA

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Dec 6, 2011
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I'm in agreement with you on this.
I've had no issues with mine.

I have a Revelation Audio Labs DB25 cable and used in on my Pass XP25 phono stage. It sounded great, but it was very stiff and mine was short. I have since upgraded to the XP27 phono with the new type umbilicals. My power supply is now far away from the phono control/gain unit. I would recommend the Revelation Audio cable. I think they actually make versions for the new Pass XS units which have different connectors.
 

jackelsson

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Dec 1, 2013
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I have a Revelation Audio Labs DB25 cable and used in on my Pass XP25 phono stage. It sounded great, but it was very stiff and mine was short. I have since upgraded to the XP27 phono with the new type umbilicals. My power supply is now far away from the phono control/gain unit. I would recommend the Revelation Audio cable. I think they actually make versions for the new Pass XS units which have different connectors.
Peter, did you buy the Revelation Audio umbilical for the initial price or for the current price? And do you still consider it a good value for the current price? I'm struggling a bit with the thought because I would need four of them plus would also need to add shipping and import tax to Germany to the total price. That's a fair bit of money for cables and needs quite a bit of thinking.

Incidentally, will you write about your comparison of your old XP-25 and the new XP-27?
 

PeterA

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Peter, did you buy the Revelation Audio umbilical for the initial price or for the current price? And do you still consider it a good value for the current price? I'm struggling a bit with the thought because I would need four of them plus would also need to add shipping and import tax to Germany to the total price. That's a fair bit of money for cables and needs quite a bit of thinking.

Incidentally, will you write about your comparison of your old XP-25 and the new XP-27?

I bought a used cable about three years ago. I don't remember the price and was never aware of the retail prices for these. I am planning to send my cable, no longer needed, to a friend to try. If he decided he wants it, I will sell it to him. If he does not want it, I will contact you via PM and perhaps you will want to buy it. It is about 0.75M in length and will be inexpensive.

I will be posting my impressions of my ten day audition period in which I directly compared the 25 to the 27. I just have not gotten around to writing up the report.
 

ack

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I really do believe the Revelation Audio umbilical - as sold now - CAN make an improvement, and perhaps a major improvement. I say this because I recently shielded my XP-25's umbilical with copper, and the decrease in noise was phenomenal, as proven by just turning the preamp volume all the way up - it was fairly quiet before after all other modifications to the phono, and it is a LOT lower after shielding the umbilical. Sonically, the bass in the Carmina Burana I first played was so tight and powerful, like never before. The improvements extended all over. Sometimes I love what Pass is doing, others I am indifferent, but when it comes to this XP-25 phono, I freaking hate how much noise this unit absorbs as shipped out of the factory, plain and simple. UGH! At least I know how to fix it. I hope the 27 fixed all problem areas I addressed.
 

ack

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I was quite aware of it and I did the mods within a couple of weeks. Pass ought to know better than this, for 10g
 

bazelio

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I was quite aware of it and I did the mods within a couple of weeks. Pass ought to know better than this, for 10g

Wow. Severely disappointing, and it's good to read this open and honest feedback.

From passlabs.com -

XP-27:
Unweighted Noise
-93 dB ref 10mV (MM)
-85 dB ref 1mV (MC)

XP-25:
Unweighted Noise
-93 dB ref 10mV (MM)
-85 dB ref 1mV (MC)


It seems the noise level is equivalent, and also very low. My MC outputs 0.2mV. Perhaps the measurement environment differs drastically from your listening environment. I'm not trying to justify anything here, as it's amazing that shielding from Pass appears to be insufficient. Sorry if you mentioned it somewhere else already, but what have Wayne or Nelson said about this?

PS - How long is the supplied XP-25/27 umbilical?
 

ack

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I haven’t talked to pass about the inherent problems in thrir phono, which include hum pickup. Not sure I would gain anything. But the subject has been discussed at length before, and noise issues are also present in the XS phono as well. I am sure pass know better, but I also have my doubts when it comes to other areas, like intentionally adding loading capacitance for MC - another subject discussed years ago on why capacitance must be minimized. I have removed that load in mine. Other problems included different gain between channels, which they fixed quickly. Poor QC.

At any rate, I can confirm, more or less, the -85dB noise level now that my unit is properly shielded. I must have dropped noise by at least 20dB to reach that claimed -85 figure. The good news is that I have read that pass have implemented in the 27 some of the shielding I have employed, and it obviously has a better umbilical.
 

bazelio

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Sep 26, 2016
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I haven’t talked to pass about the inherent problems in thrir phono, which include hum pickup. Not sure I would gain anything. But the subject has been discussed at length before, and noise issues are also present in the XS phono as well. I am sure pass know better, but I also have my doubts when it comes to other areas, like intentionally adding loading capacitance for MC - another subject discussed years ago on why capacitance must be minimized. I have removed that load in mine. Other problems included different gain between channels, which they fixed quickly. Poor QC.

At any rate, I can confirm, more or less, the -85dB noise level now that my unit is properly shielded. I must have dropped noise by at least 20dB to reach that claimed -85 figure. The good news is that I have read that pass have implemented in the 27 some of the shielding I have employed, and it obviously has a better umbilical.


Yeah, not being familiar with the product, I was also wondering if the capacitance settings only applied to a "MM input". So I downloaded the user manual yesterday, and to my surprise, found that its inputs are general purpose so that cap loading applies to either MC or MM. By "removing that load" do you mean you invalidated your warranty by desoldering something internally?

I guess all products have their quirks, but this noise issue is very disappointing. I suppose it still can not hurt to audition the 27 for myself, still. My current phono stage is certainly far from the quietest on earth.
 

ack

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Yes I unsoldered the 100pF load capacitor.
 

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