My email said this is a reply to me… What motivates you to say that?
God forbid he does any tests on the topic at hand and reports his findings.
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I think it may be clear to some (most?) folks at this point, but I want to (hopefully) help others understand what sort of problem you have. Given the above statement this is NOT a ground loop problem, rather it is high frequency “hiss”. To audiophiles (and other music related folks) “hum” infers a ground loop which is manifested in a 60 Hz or 120 Hz “hum” from the speaker. Several posts talk about power, cheater plugs, etc. which are solutions for ground loops. This is an amp internal characteristic as Paul has stated.
Now, at the risk of annoying you, and that is NOT my intent, the noise issue when using single ended interconnects has been discussed previously. It’s not a secret and I would be surprised that PS Audio folks did not understand that. I wouldn’t expect you to know this since you indicate you don’t keep up with the forums, but I’m surprised (again) it was not pointed out quickly by other members. Sometimes we all miss the point …
Anyway, I would reiterate what has already been said that given the amount of money invested at this point a simple pair of Blue Jeans Cables XLR/balanced cables for less than $100 would be a cheap and effective way to solve the problem. Should you want better there’s Iconoclast BAV for less than $400. The point being you can get more than satisfactory performance for a small investment.
Good luck!
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It is obvious now that balanced cables are the only way to run these amps, a point that was never made clear to me in the countless hours I spent with tech support. Obviously there are enough other cases of people having the same problem that I know I don’t have “bad” amps, something I was always under the impression of.
I have no issue now running balanced, knowing SE is an absolute no go with these amps.
My problem is that I spent hours and hours troubleshooting with tech support, while they knew full well the issue I was having was with SE. Instead of just saying you can’t run SE with these amps I spent hours doing test after test after test after test. Researching on my own trying to fix this. I would even be told things like they’ve never seen this problem before, so you can see where it is upsetting for me, thinking something is wrong with the amps or something on my end.
Anyways I’m past it all. As long as I now know I don’t have faulty amps and the issue is “quite” common, I will move on and just buy balanced cables.
Hopefully this thread helps somebody in the future who is planning to, or trying to run single ended.
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Your identification of the noise as “hum” had everyone, including PS Audio Service, putting a lot of energy into trying to solve a ground loop. Your description of the problem threw everyone off.
The responses you would have received would have been very different if you had identified the issue as high frequency hiss “100% coming from the tweeter.”
In any event, your issue is now resolved. @pmotz provided you with some excellent, very affordable options for balanced cables.
Best of luck going forward.
Thanks for the smart a** reply. Michael Fremer himself identified the issue as “hum”.
Hum is clearly something that is resolved with cheater plugs, something that worked for me. Ground loops can be resolved with cheater plugs, again something that aided my problem.
My problem was explained very very clearly to tech support and was stated as “a hum or hiss”, every time. Thanks for your insight though.
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I have no idea where you get the notion that the BHK’s PRE and 300’s can’t be run single ended. I have run them both ways and have never had the issues that you’ve had. Yes it’s frustrating but it’s not common to all users. I did have an issue with one of the BHK mono’s and the input board was replaced. The only thing I have is a tiny left tweeter hiss at 1 inch from the tweeter and it’s likely the tubes I use.
I did not say it’s common to all users. If you read my last post I said “quite common”.
Sorry for your troubles, but that statement is simply not true. That’s why no one here or at PSA said that.
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If the statement is not true, then he has an issue with his 300’s, and it should be covered under warranty.
I am sorry I struck a nerve. This is not my intent. It is rather an attempt to put the issue in perspective and add some clarity.
Again, good luck. If you need more suggestions for XLR cables, from cost-effective to top-of-the-line let us know. As you have seen from this thread, this group is happy to dive in and help.
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You might be right. Perhaps he should send everything back to have it all checked out.
Many happily run the amps single-ended with no problems. My guess is the vast majority do as people like RCA terminated cables and they are more versatile as a lot of equipment does not accept XLR.
As you know, there are many, many things which can impact how a component works in any given system. We do not know the cause of hiss in his, we only know the solution is to run balanced. This does not mean there is something wrong with the amps, only that running SE in this system is not satisfactory.
Fortunately, the OP now has a solution to his issue and can move forward to enjoy his system.
A lot of stereo equipment is optimized for either XLR or RCA. I had an Ayon tubed CD player that had both XLR and RCA outputs. I used XLR.'s because the amp I was using was fully balanced. But the distributor of the CD player told me it was optimized for RCA and would sound much better, probably because it wasn’t truly differentially balanced. I did give it a go with a cheap pair of RCA’s, and it did indeed sound better.
Personal experience with the BHK300’s related to hiss (hiss, not hum, I have never experienced hum in my system).
When I first got them I only had SE but they were high quality SE that I had been using for years. My previous amp/set-up was dead quiet. The BHK’s “hissed” with the left channel being louder than the right. The left was loud enough to hear fluctuations in the hiss. Additionally, because the right was now next to the right speaker, I plugged the amps into the wall using the supplied power cables. The hiss was slightly audible at the listening position but I also have a quiet, acoustically treated, room. It should also be noted that my setup has a lot of gear near the left channel (a multi-channel amp as well as video gear so extra power cables, interconnects, etc.).
Part of my upgrades this year, including the BHKs, was to order a new pre and nice XLRs. This took me a few months before ordering and having everything installed. In that time I experimented with a few things to reduce the hiss. What reduced it more than anything… I pulled the power for the amps to the front of the cabinet instead of behind. They no longer sat next to anything else. I ran both amps into my power conditioner. That required running an extension cable to reach the right amp (nothing special about the extension cord; just one I had in the garage). That reduced the hiss pretty significantly in both speakers but the left channel was still louder. It was difficult to hear the hiss at the listening location.
I upgraded the pre first and left it SE. No change in hiss.
I then switched to XLR from the new pre to the amps and the hiss was gone. Speakers are quiet unless, maybe on some nights, you literally attach your ear to the tweeter.
After upgrading the XLRs I upgraded the power cords and got rid of the extension cable. Now things are consistently quiet at the speakers.
I still use SE sometimes and the hiss comes back with the left louder than the right. I also noticed that some SE cables have more hiss than others. In fact, since I’ve got a bunch of the same SE interconnects on my multi-channel amp, I swapped in the quietist ones. All the same brand/model/length and, yes, some produced more hiss than others. All of those cables are dead quiet on my multichannel amp.
I think, as you’ve already identified, XLR is the solution. This is “hinted” to in the BHK manual. For me, XLR was going to be a nice to have. My limited technical understanding, based on my cable lengths, is that I shouldn’t hear a difference between the two. Well, obviously, the technical “proof” about cables don’t take into account the gear sitting on each end when one of those pieces of gear (or both) simply wants to be balanced. XLR is required in my setup if I don’t want hiss. I’m “OK” with that.
It is surprising that many cannot seem to get a dead quiet signal on SE with these amps but, as I say that, I also strongly believe moving to balanced should be the goal of every audiophile. After experiencing the benefits of XLR I’ve firmly planted myself in the “balanced rules” camp. If the design of the electronics is balanced… from now on… I’m using balanced cables. It’s a cheap swap that makes a difference.
PSAudio should just state, stronger than they already do, that this is a balanced design and it expects to use balanced cables. That limits who I can recommend the gear to but those willing to switch I recommend the BHKs highly.
How long are the interconnects you were/are using?
The RCA are 2m and I went 3m on the XLRs to give me some extra routing options.
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Glad to hear. Enjoy the system!
This was the issue I had with the first two sets!
First set the left was MUCH louder than the right.
Second set the left had a sort of flutter or fluctuation in the noise.
Both cases were not tube related. Tried swapping tubes around but it did nothing. The noises always followed the left channel output on the preamp.
I also think vee mentioned in this thread when he hooked up SE he had something going on in the left channel. Really weird to see the same sort of issue always in the same channel.
I have followed some of this discussion. For what it’s worth, this was my experience:
I do believe the BHKs are unusually sensitive to hum (or whatever anyone wants to call it, sounded like 60hz hum to me) when using unbalanced interconnects. I posted about this very issue when I owned the BHK 250 (pretty old post at this point). I initially used unbalanced interconnects from my Cary SLP-05. I did elicit a response from Paul but it was unhelpful. Lifting the ground pin on the power cord resolved the noise. Ultimately, I re-installed the ground pin on the power cord and purchased balanced interconnects, still using the balanced interconnects with the BHK 300s.
I still have a very small hum from the system but it’s one of those put your ear to the speaker things and I don’t care about issues like that (don’t listen with my ear next to the speaker).
I have not tried unbalanced interconnects with my BHK 300s but believe the system would exhibit the hum. My previous amp to the BHK 250 was a Parasound A21 and didn’t hum at all with unbalanced interconnects (the A21 uses a clever switch to lift ground if necessary but I didn’t need to deploy it). BTW, I would have sold the BHK 250 in 10 seconds before selling the SLP-05 if I couldn’t eliminate the noise.
Edit: The P20 nor the P10 made a bit of a difference regarding the hum.