Help and Advice Needed: Cary Audio SLP-05 Preamp RMA Disaster

@mulveling is absolutely correct. 6V balanced/3V RCA is getting more and more common, and for very good reason. My Holo May is not unique, the Chord Dave is 6V on XLR.

The Cary 200TS is 3V RCA and +/-3V on XLR
And no I am not confused about RMS, +/-3V is 6V total - there should be no debate about this. Their manual even recommends setting the output to max (3V) when using a preamp.

High output voltage on a DAC is very desirable, and it is why most companies seem to be headed that direction.

I don't want to paste a quote from the emails they sent me because I have no idea what the laws are about this (or whose state the laws would come from).

So, I will paraphrase:

The balanced signal enters the amp, and is summed by the input buffer. Even with the volume at zero, current passes through the tube and into the ground plane which is shared with the line stage. The reason the right channel was affected more than the left channel is because the right channel input buffer tube is next to the right channel gain stage, which causes a great deal of interaction with a coupling cap that is nearby.

This comment just raises all sorts of questions, whose answers are all "Ya, but it shouldn't."

The actual circuit in the Cary is like this: the signal passes through a relay, into the input buffer tube, to the volume, then to the gain stage and out to the power amp.

So signal should (in theory) pass through the plate of the input buffer, up a wire to the attenuator and stop if the volume is at zero. It does not interact with the ground plane until it passes through the attenuator.
The only way for signal to enter the ground plane is by some kind of coupling, in this case the signal was coupling via a capacitor.
So why is the signal not better protected? if it can couple with cap, then the cap can couple with it. In other words, if the small signal input can couple with and energize the line via a capacitor stage, then the line stage can also couple with the  small signal input.

Honestly, they fed me so much BS, the above paraphrase being just a small part of it, that I doubt they even found the problem. I have been under the belief from the beginning that the amp simply has a solder or flux bridge somewhere. As they kept telling me, they have "sold thousands" of these with no problem. I am sure hundreds of those are hooked up Chord or Holo DACs. I would even bet that this thread has been read by people who also have a DAC with my voltage output.
From the moment I sent my first email about it, the response was "it passed QC before be shipped it, and it is perfect." Weeks of emails, and it never seemed to get through to them that my gear is not unusual and there is probably something wrong with my unit. All they would have to do is grab another one off the burn I rack and test it.

Ask yourself, if would anyone here actually pass on to a customer the statement from a tech that "your amp has too much gain, too many watts, and your speakers are too sensitive" with regard to volume bleed through and channel cross talk?
This just screams a tech who is not able to make mistakes without serious consequences. As for the QC manager, either he is willing to feed me serious BS, or he is incompetent.

They tried one line of BS after another until they got fixated on the 6V output from my Holo May, and ignored the fact that I had to switched to using a different DAC with lower output voltage.

So yes, Cary has lost its healthy organizational culture and is a downward spiral. 

The problem does not exist with RCA input.

I only tested it with an RCA analog cable (Audioquest), not a properly rated SPDIF data cable.

I think I get where you are going with the idea since SPDIF cables are rated to have very specific characteristics.

Thanks,

-Josh

@acresverde

I did not try swapping for different cables, but I did think to verify the pins are correct.
Also, Cary was finally able to replicate the issue with their cables and gear.

@avanti1960 

Why not use RCA? Aside from the generic benefits of XLR, both the Holo May and the SLP-05 are reported to have the best output using balanced. I have found this to be true of the Holo May, but I have only listened to the SLP-05 for a few days in the 3 months I have owned it since it has been at the shop the rest of the time, so I can’t comment on sonic differences.

Also, using XLR lets me have a fully differential system from DAC through amp.

Thanks,

-Josh

@decooney 

Huh - confused - How so?

Were details shared about how they were able to replicate the issue?

Sorry if I was not clear.

I could feel my blood starting to boil again when I was writing the details. This whole affair has been the worst customer service experience I have ever had.

Both of statements are true:

Cary is being absolutely resolute in stating that my situation is entirely unique and caused by my "unusual" gear.

It took 3 weeks of wrangling before they finally RMA'd for the damage FedEx caused. They never issued and RMA for the signal issues, and they where only able to duplicate the issue after I gave them explicit instructions.
here is the email I sent them regarding instructions:

On Nov. 2, the day my SLP-05 came back, I emailed you. On line 3 of that email, I stated the amp would not turn on, and described the loose tube and capacitor. Near the end of that same email, I mentioned that FedEx could be blamed for damages. I did this intentionally to provide Cary Audio and honorable path to address my issue and get the preamp back.

 

I do not understand how you can say you did not know about the damage.

This is just one of the many examples of why I feel like my concerns have not been heard or have been brushed off, and is the root of why I am so upset and angry over this entire affair. Add to that, what knowledge of electronics I might posses has not been considered when making what are obviously nonsense replies.

 

If you have not duplicated the results, it is because you have not duplicated the experiment.

I suggest using the test tone I provided in an earlier email.
I suggest ensuring the voltages measured using that test tone match or exceed the ones provided for the Matrix DAC in that same email.

pin1-pin2

pin1-pin3

pin2-pin3

Matrix DAC LEFT	1.085V	1.084V	2.170V
Matrix DAC RIGHT	1.083V	1.081V	2.164V

I have attached the test tone wav file again.

I suggest not using a speaker with the sensitivity of a brick.

Note the above voltages are not far out of line with <Tech>s Nov. 18th statement "...standard line-level signal (typically 1-2V RMS)." I will not debate the validity of the statement, just point out (again) that Cary DACs are 6V RMS, as well as other standard high end DACs (the Chord Dave for example).

 

I make these suggestions as a person who not only designs and analyzes experiments for a living, but often has to duplicate the results of other scientists.

it was after that email that they duplicated the problem, and made the suggestions I detailed above.

Thanks,

-Josh

@gs5556 I saw that article when I first started looking online for others having my experience. I agree, I think Cary knows this is an issue and is doing everything they can to keep their heads in the sand. 

@harpo75 Your discussion mirrors some of what Cary has shared with me, in particular that the signal passes through the input buffer before it goes to the pot in XLR. They say that because of the "extreme" voltage, the signal is leaking into the ground plane and energizing the rest of the circuit.

But as you say, this should not cause any volume leakage, at least it shouldn't if the circuit is properly designed. So, somehow, signal on the ground plane is getting up into the plate and getting amplified.

Good info about the Kimber Kables, I did not know they where not shielded.

This just tells me they are selling a poorly designed input stage and/or a poorly implemented ground plane.

@decooney 

 I brought this up earlier and OP went right back to justifying XLR again instead of re-evaluating this as a serious option, look for lower-gain source and preamp gain particularly with high sensitivity speakers. Try again with RCA!

Not sure what you are referring to. @avanti1960 asked about RCA, and I provided an answer, not a justification. Consider also, I just spent $9600.00 on this thing, is it not reasonable to expect it to work with out compromise? There are a ton of equally good or better preamps out there that are RCA only for much less money.
I answered your question about how they replicated the issue.
I am happy to answer any questions on the subject, I am really hoping for a solution that can get me back to enjoying my preamp.

@mm1tt77 Thanks. I have considered attenuators, I have even heard some claim they improve the sound, though I expect this is from providing more headroom before clipping.

Adding an attenuator is certainly preferable to letting Cary hack in an 80% voltage reduction.

On the subject of XLR vs RCA I am not adamant about one method being better than the other. It comes down to implementation and design.

In my case, both the Holo May and the Manley Snappers are designed from the ground as fully differential. Adding RCA to these units means the signal path has to be altered from the original design intent.

On listening, XLR between the DAC and amps is noticeably better with no caveats than RCA. In my set up, XLR is better in every way, and RCA is inferior in every way. On almost all tracks, it is easily and immediately noticed.

Using RCA is a compromise I am simply not willing to consider. I paid a lot for this system, and I expect to get the most out of it.

I am in the middle of another round of emails with Cary. I will give an update soon.

I really appreciate all the comments so far. They have been helpful, useful, and on topic. I have had a presence on the internet since it was newgroups, and I have to say this forum is one of the best I have used in both the quality of the people, and the quality of the information.

-Josh

One of the nice things about the SLP-05 is that it will convert RCA to XLR or vice versa internally with out issue, and was one of the many reasons this amp appealed to me.

After much debate, I requested a refund. The owner proposed a dollar amount that I consider fair. This was complicated a bit by the fact that they gave me more than my trade in was probably worth, and sold it for less than they gave me for it.

I reached this decision based on several things:

My interaction with the Quality Service Manager is probably the worst customer service experience I have ever had. Not only was he willing to say things to me that are simply wrong, he is unable to listen to a customers concerns and address them. Having owned business' in the past, I can say I would find another role for this person or simply fire him. He is damaging Cary's brand every time he opens his mouth.

Because of these interactions, my trust with Cary is nil. If I am going to pony up nearly $10K, I expect to not have trust issues.

During the 3 weeks it was here before it got sent back a second time, every time I would turn it on, my pleasure was always tempered by anger and frustration. This is simply not the way to "enjoy the music."

I suppose it is also not a good fit, tho I didn't really have here long enough to really know. in total, it was here for about 2 weeks before the first RMA, and about 3 weeks before the second RMA over a period starting Aug. 12 and ending Dec. 14 when I requested a refund. During that same time, my lab submitted 2 grants, and 5 papers for publication of which I was first author on 1 and co-author of the rest. So not only did I not have as much time to enjoy the music as I would wish, those times I needed to enjoy the music where greatly diminished.

So, now I in the market for a new preamp.

Must be balanced.

Must have remote volume.

cost about $10K or less.

I prefer having a HT bypass.

I welcome any suggestions, tho I will probably start a fresh "need preamp advice thread" thread when I get back from vacation.

I will be gone til after Christmas, so I will reply to any comments then.

I want to once again thank all of you for all the thoughtful, useful, and enlightening comments. As I said before, in the 30ish years I have been using the internet, this forum is one of the best in terms of quality of people and information.

-Josh

I want to thank you all again.

Sorry to get back to this thread so late, my internet was down until last Thursday, and I have been getting caught up with other things after getting back from vacation.

I have spent much of the last week reviewing my notes and thoughts that led to my initial purchase of the Cary, and used that plus this experience to chose a replacement preamp. I chose to go with a BAT VK-33SE, I think it might synergize better with my Manley Snappers.

It is interesting to note that many manufacturers publish the rated input voltage, Cary does not. Imagine how much different my experience would have been had they published this info. They could have simply pointed at the spec, told me to find a way to meet it. I would have simply sent it back and taken responsibility for not doing my due diligence, as well as the loss for shipping and restocking. In stead, they wasted months on passing blame around and covering each others butts, and made me a very unhappy customer who will be happy to share my experience with others.

In fact, I most likely would not have purchased it in the first place because I do pay attention to details like this.

I disagree with the comments that it is difficult to design the amp to handle higher voltages - it is actually easy. One needs simply to attenuate the signal before the input buffer - the SLP-05 does this on the RCA inputs, but not on the XLR inputs. I assume this is to save on cost and complexity since attenuating both legs of a balanced signal requires well matched components. This is the reason the signal was bleeding through at zero volume.

The source of the cross talk, and why the signal bleed affected the right channel more than the left is from a poorly located capacitor, and Cary was able to cure this by relocating it.

These are two separate design issues, one is a design choice, the other is a design flaw in the layout of the PCB itself.
 

It is my belief that Cary knows there is issues with this preamp. Considering the review linked by @decooney above showing pretty poor performance with respect to cross talk, it is impossible to imagine they are not aware of this issue. 

Judging from my experience and others, I think Cary has lost its healthy organizational culture, and is on a downward spiral.

Thanks again,

-Josh