Coherence II questions

engadin

Member
Apr 23, 2022
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I am the happy owner of a Coherence II preamp.

A few qustions:

As the cord to connect battery power supply with preamp has deteriorated (outer isolation falling off in pieces), I ought to replace it.
Would it be safe to use the old cord with a new outer shrink wrap?
I am afraid the cable‘s inside isn‘ t much better.

Are there alternative cords, maybe better sounding ones?

Battery swapping: any tricks to get old batteries out?
One always gets stuck inside and wouldn’t move …

Other batteries than those Panasonics originally used you can recommend?

Should I give these here a try?

Thx in advance for your input and any other info for Coherence II information!
 

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sbnx

Well-Known Member
Mar 28, 2017
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Call Jeff Roland. He is very nice and helpful even on his older products.
 
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sbnx

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Mar 28, 2017
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Awesome preamp!
 

engadin

Member
Apr 23, 2022
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thank you, sir!
 

engadin

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Apr 23, 2022
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Indeed, best ask Jeff. He wrote:


Jeff Rowland (Jeff Rowland Design Group)
Apr 24, 2022, 14:42 MDT
The rubber sheath has degraded due to age and does not affect the electrical characteristics of the cable. The best and less costly way to restore the look of the cable is to slide a length of heat shrink tubing over the entire length of the cable, shrink the tubing with heat from a heat-gun or put the entire cable in an oven set for 120 degrees C, until the tubing tightly shrinks over the cable outer shield. This is what we have done in cases like yours.
 

engadin

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Apr 23, 2022
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605F6A78-7692-4A85-A783-8F69EA9A4AA1.jpeg I am very glad to answer one of my questions myself:
How to get those friggin‘ batteries out?
Rubber gloves to get a better grip?
nope
Have it upside down and wait?
nope
Silicon spray?
nope
Warm it up somehow to widen the aluminium housing?
nope

Desperate situations … desperate measures.
I glued with epoxy two flat rocks as handles on top.
Voilà, here it goes!

I think I‘d better put two stripes of parcel stripes round the new batteries for easier removal next time.
 
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engadin

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Apr 23, 2022
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Ah well, this and other fora bring odd ideas.
Fancy fuses for astonishing amounts of money.

In the end, I ordered two fuses from Synergistic Research.
Purple ones, one for the Ferrum Hypsos, power supply for my router, and one for the drawer at the power connection at my Coherence II.

But there are still two more similar looking fuses inside the battery power supply close to the connectors of the two batteries to the pc board.
Those fuses don’t come out easily, they are not that easily removed.

Has anyone tried some fancy fuses there?
What kind of fuses are they?
Slow or fast? Amperes?
 

microstrip

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May 30, 2010
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Do you know how to distinguish a Coherence MkI from a MkII? As far as I see the back label does not refer to Coherence II, it just says Coherence.
 

engadin

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Apr 23, 2022
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Easy.
MkI looks totally different, have a look at the attached pic which I stole elsewhere.

Otoh, there are Mk II series 1 and series 2.
To the best of my knowledge you have to open the pre, not the bps, to tell them apart.
Red pc boards: Coherence II series two
Brown boards: Coherence II series one.
Bps has brown boards in both versions.
 

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microstrip

VIP/Donor
May 30, 2010
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Easy.
MkI looks totally different, have a look at the attached pic which I stole elsewhere.

Otoh, there are Mk II series 1 and series 2.
To the best of my knowledge you have to open the pre, not the bps, to tell them apart.
Red pc boards: Coherence II series two
Brown boards: Coherence II series one.
Bps has brown boards in both versions.
Thanks - but I was addressing the two versions of the more recent Coherence II you own, not the Coherence One!
 

Birdwatcher

Well-Known Member
May 29, 2018
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Hello,
the Coherence II Series II has serial number of above 500, maybe even some of the 400 numbers are on Series II level, I am not sure.
The highest serial number I know of is the 644.
 
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oceanic

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Feb 27, 2022
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For batteries you can use any similar type, to distinguish between series I or II of Coherence series II preamp by the eye. the difference is the circuitboard color in the amp module section when in the case of I is brown/green and in the case of II is red. (Note: in the power supply section the color is the same brown/green)
 

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