Ref 2SE phono problem, any insights?

[patrick]

Hoping the ARC expertise here can help me diagnose a problem.

So, I have been happily using an ARC Ref 2Se phono stage I picked up last year as the line was phased out. Bought new from authorized dealer not local to me. Been lovely until now. Couple of days ago, I played some records and thought something was not right. The volume on the right channel was distinctly quieter than the left. Thinking it might just be a recording, I parked the thought away until the next day when I confirmed this to be the case - music is just louder out of one channel.

I played CDs for comparison, system sounded fine, the imbalance was only on vinyl. OK, maybe a loose connection so traced everything back from cartridge to preamp, no obvious problem. Quick check of the cartridge with my Fozgometer indicated both channels putting out similar levels on that measure, reseated phono cable etc. Still hearing the problem.

Contacted ARC for help and their email response was to check everything again before assuming it was the phono stage or tubes. Had me reverse input cables (no change), output cables (no change, other than what was once on the left side came out the right, and vice-versa, but the right channel still a little lower in volume), then swapped tubes 1 and 2, then 3 and 4. Minor change, maybe, maybe... but the volume difference in channels still apparent on the same side.

Today I installed another cartridge just in case but no dice, same problem. Further, I am sure the high gain setting I use is not giving me as much general volume as before, I have to turn the dial a bit more to get levels I am used to hearing in general.

So, I am fairly sure the problem has to be in the Ref2SE but the guy from ARC is not convinced and suggests I find a way to test the phono stage in a friend's system (would I had friends who had vinyl rigs!).

Any thoughts on this? I am going to try a new phono cable just in case, but the one I am using is new and is seating well at both ends. I've tried both inputs on the phono stage. I don't just want to drop a couple of hundred bucks on new tube set in case that's not it (the current set have only 650 hours or so on them) but I am sort of flummoxed by this.

thanks

P

[cleeds]

Originally Posted by patrick

Hoping the ARC expertise here can help me diagnose a problem ...

I'm sorry, but you probably don't want to hear this. Statistically, the most likely explanation for your problem is a failing tube. The cost of replacement tubes is an inherent part of owning tube components, and I've found it best to keep tested spares on hand for circumstances just such as yours. I realize you'd like to avoid that expense but - sooner or later - it's inevitable. The sooner you acquire the tubes, the sooner you'll have problems such as this corrected, whether it's this time or next time.

[audio bill]

If I understand what you did regarding cable reversal, you said that when you reversed the left and right OUTPUT cables from the ARC phono stage the right channel remained lower in volume. That indicates that the imbalance is NOT in the phono stage or anything earlier in the signal path (not the cartridge, tonearm wiring, or phono cable.) Since the right channel remains lower in level that indicates to me that the problem is after the phono stage. Since other line inputs don't experience the imbalance, I would first try a different input for your phono cables into your line stage but if that doesn't change anything I would suspect the output cables from your phono stage into the line stage may be at fault.

[cleeds]

Originally Posted by audio bill

If I understand what you did regarding cable reversal, you said that when you reversed the left and right OUTPUT cables from the ARC phono stage the right channel remained lower in volume. That indicates that the imbalance is NOT in the phono stage or anything earlier in the signal path ...

Having re-read what Patrick wrote, it seems ambiguous, so I hope he clarifies this.

[JPrest]

I would agree it is a tube issue, might be the best to get a spare set, there is good information on the web of how to identify the late 80's early 90's NOS tubes. I am using them in my REF 5SE and Ref Phone 2SE, I find them smoother is all I will say, not better just more to my preference...
Good luck keep us informed as to your progress.

[patrick]

Thanks folks --

first, if it is just a tube issue, I'd be happy enough but the tube reversals do not indicate so. Of course, I realize tubes need replacing over time (played guitar amps for 40 years) so no problem buying new ones eventually for the Ref2Se...but don't want to drop a couple of hundred bucks now with no confidence it will make a difference.

second -- agree, I need to check the output cable change again -- just in case I am mis-interpreting the outcome. Once the musical signals changed channels, that sort of confused my listening so I want to re-check that the volume levels were as was with several recordings. So what I should expect, if the phono stage has a problem in one channel is that the signal drop should switch sides?

I did try a second preamp input in case I had a bad connection in one, but this did not cure the problem and the digital front end, also feeding the same preamp, has no imbalance so I ruled out the preamp as the source. However, this is a preamp with one pair of balanced inputs (which the digital rig is on) and several single-ended inputs, which I did test the phono stage on. I suppose it is possible that the SE inputs on the preamp all have a problem while the balanced does not...let me check this with some balanced cables from phono to preamp. I did actually try two different sets of cables between phono and preamp so I am sure it's not the cables themselves but I suppose it could be the SE inputs on the preamp, unlikely as that seems that they'd all go at one. I can also ask the designer for some guidance here, he's very responsive (Steve McCormack).

I'll report back when I have more data. Let me reiterate my appreciation for the help here, you can imagine my frustration when something so good stops working. Am hoping also to find a way of scaring up another phono stage to install here, just to check. I am really hoping I do not have to send it back for repair.

Best

Patrick

[JPrest]

Even if you send it back to ARC they usually turn it around quickly, I just sent a D350 Amp, I was going to sell for parts, and two weeks later it was back at my dealer, Audio Perfection, and the repair bill was $65.00 dollars for a resistor replacement! If I wasn't local to ARC the freight alone would have been well over $100.00....

[tima]

Originally Posted by patrick

Had me reverse input cables (no change), output cables (no change, other than what was once on the left side came out the right, and vice-versa, but the right channel still a little lower in volume), then swapped tubes 1 and 2, then 3 and 4. Minor change, maybe, maybe... but the volume difference in channels still apparent on the same side.

Originally Posted by patrick

second -- agree, I need to check the output cable change again -- just in case I am mis-interpreting the outcome. Once the musical signals changed channels, that sort of confused my listening so I want to re-check that the volume levels were as was with several recordings. So what I should expect, if the phono stage has a problem in one channel is that the signal drop should switch sides?

Yes. If you switch the Ref 2SE output cables at their output sockets and the lower volume channel switches to the other speaker, the issue is more likely in the phonostage than downstream.

When swapping tubes, best to swap channel for channel. That means swapping both V1 and V3 with V2 and V4.

A crude and not definitive test of the microprocessor controlling channel volume is to change the balance to entirely one channel and then entirely to the other channel. Listen to see if the relative volume difference remains the same for the channel that plays music; and listen for any noise or music in the quiet channel. (Listen from your chair, not with ear to the speaker.)

ARC support is correct in suggesting to place the phonostage in a different system and see if the volume imbalance moves with the phonostage. (I believe there are other vinylists in Austin - why not ask on this board.) That's definitive. Next if you can borrow a phonostage, replace it for the REF2SE; if the problem goes away, then its very likely the 2SE. ARC will want you to do every test you can before shipping the unit to them for repair.

I wish you well in getting the issue resolved. If you're lucky it will be a tube issue.

Which brings us to this: Cleeds is right. If you're gonna own tube gear, you may as well come to grips with the reality of doing so and buy (at a minimum) a couple 6H30s. You will not get your tube gear ownership merit badge until you do this. A pair of ARC grade 6H30s from Upscale will cost you under $100. You can find them cheaper, but buy from a reliable dealer who will back them up. When you get them, try them out for 20 hours or so, then put them in a drawer basking in the glow that comes from having a cheap bit of assurance knowing that when a tube goes (and they all do eventually) you are prepared.

[cleeds]

Originally Posted by patrick

... if it is just a tube issue, I'd be happy enough but the tube reversals do not indicate so.

I don't think you've ascertained that, because you haven't tested either of the power supply tubes.

Originally Posted by patrick

... I need to check the output cable change again -- just in case I am mis-interpreting the outcome. Once the musical signals changed channels, that sort of confused my listening so I want to re-check that the volume levels were as was with several recordings.

Using a mono LP or a proper test LP might make this easier.

[patrick]

Thanks for the pointers. OK, update, and still slightly confusing.

Listening as normal this morning -- solo guitar from Joe Pass. Left channel dominates. Some sound from right channel but the familiar problem as described above.

Changing output cables, so left output cable from phono is switched to the right output, and the right cable is switched to the left output, original connections at the pre-amp left unchanged, definitely shifts the soundstage. Oddly, the sound does not just shift predominantly to the other side as before, in a mirror image, rather it is slightly more balanced between the two with the right channel sounding like it's playing a role in proceedings now. BUT, overall, it is quieter than I am used to hearing at that position with the volume dial. Sounds like I am listening on the low-gain setting of the phono stage, not the high gain where I usually set it. The low gain setting itself is practically inaudible now compared to before.

Moreover, though hard to be precise on this, the music just does not sound as good as I think it normally does but that's harder to pinpoint, might be warm up though it's been through a few sides now-- sort of lifeless and lacking some of the nuances, air, decay and resolution. Harder sounding all round. That last part certainly suggests the tube problem might well be it but I don't know how to explain the channel effect I'm experiencing from the cable swap.

Looks like I need to spring for some new tubes just to rule this out. I want to check on suggestion here about swapping tubes 1 and 3 and then 2 and 4. The ARC guy specifically indicated swapping 1 and 2, then 3 and 4 but I presume no harm in trying all combos systematically.

CD player still sounds fine through preamp so am going to make some adjustments in rig so as to be able to plug the phono stage into that preamp input just in case it really is something in the preamp SE inputs but that takes a bit of effort. I'll report back. Also have email into local dealer who sells lower end ARC to ask if he'd let me bring it in to check on one of his rigs. We'll see what he says.

Thanks all















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