Scotte1, do you have any evidence of people not experiencing hum with BHK amps and single ended connection?
SE into balanced is usually not a problem it’s the other way around.
i wonder if anyone has experienced this in the uk?
there does seem to be a much wider variation in wiring and earthing practices in the US, which may account for some folks experiencing this and some not.
note i don’t have BHKs, but i am told we have VERY rigorous and consistent standards in wiring and particularly earthing in the uk.
note also NOT a criticism of US wiring, i am also told that UK standards are considered by some to be OTT.
My home obviously has a transformer somewhere, and I assume it’s center tapped to ground since the voltage here is single phase 240V and center tapped to give 120V to ground.
I’ve also tried using a balanced power supply which should help with some of these problems I believe and results are the same.
@robbbby: I don’t have ANY personal experience. My inference from being a regular here is that only a few people have reported struggling with this on this forum. IIRC, it leads me to believe that there MAY be factors (along the lines of some of the things @vee has mentioned) beside the amplifier design that can lead to your experience.
Hopefully, some other BHK amplifier owners with SE experience will chime in here.
Regards.
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Commonly, one would use XLR when there is a noise problem to solve.
And you have stated that the balanced cable indeed solves your problem.
So why not use XLR and be done with it?
And I would guess that a good answer to your question about why the RCA connections are there is that they get used when one’s circuit is clean enough. These components are not new to the market. And I’m sure there are lots of users using single ended connections without problems. I did when I had this combination.
The reason I ask is an on-the-ground iso transformer that’s outside your house running into a main panel at the house that is also grounded separately will create a potential on the ground line via earth.
Also, a balanced transformer won’t isolate ground. A properly done balanced iso transformer will connect ground on the balanced side to outlet ground.
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For your reference, I ran SE from a phono pre to a BHK Pre. That connection hums, but isn’t audible at high listening level–only at speaker shattering level. It hums loudly when sitting parallel to the wall wart cable.
My Pre is, however, hooked up to the power amps via balanced. Although I could use SE, there are too many parallel wires (power, speaker, component) going on behind the equipment stand and not enough space to route them sufficiently far from each other.
I would hope this isn’t true and it certainly isn’t in my experience. Have you contacted us for help resolving your issue? Who did you work with at PS?
@Paul: Of course it is your prerogative to accomplish the customer service follow up as you see fit. In light of the fact that you have probably not had time to read this entire thread, can you/would you answer a “burning question” in the interim:
Is hum or noise (at some level or another) inevitable if you use SE interconnects with BHK amplifiers instead of XLR interconnects?
My hypothesis is that those that experience audible noise at the listening position using SE interconnects are a minority of BHK users and that if said noise (hum) only goes away with the use of XLR interconnects, then those folks are the victim of an electrical/ground gremlin caused by something else in the power and/or signal chain.
I understand that by their nature properly designed/executed balanced circuits used with balance (XLR) cables will ensure that any noise that is common to both the hot and cold pins is cancelled out. However, what I am hoping to confirm or debunk is that the SE input path to the BHK amplifiers is not inherently and significantly prone to produce audible hum/noise compared to the balanced inputs.
“Inquiring minds want to know.”
Thanks in advance.
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In my experience, there’s a definite increase in noise with single ended cables. The noise I am referring to is a bit of hiss as well as increased “clicks” when using the volume control. This happens because the BHK circuitry is fully balanced from the output of the tube onwards. This means you’re listening to but one phase of the audio (we don’t sum the two phases for SE output). I haven’t experienced any increase in hum, though much depends on the sensitivity of your loudspeakers (there’s always some residual hum on every preamplifier).
Using balanced interconnects will reduce the noise that is there by a decent amount depending on the common mode rejection ratio of the amplifier. If the BHK, that’s quite high and so whatever noises are common in the preamplifier will be reduced quite a lot.
This reduction of noise when going balanced vs. SE is not exclusive to the BHK preamp or amp. It’ll be that way on just about any product that is actually a balanced circuit (many are not).
Hope that helps.
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Paul:
Thanks for the prompt response!
Stay safe,
Scott
Of course they are going to say it’s not common, yet there is more than enough evidence to support that there is.
What is your hypothesis based upon?
Not everyone uses the forums. My own distributor told me that he sold a set to another gentleman halfway across the country who experienced the same thing. They tried resolving the issue but the guy ended up selling shortly after.
There is more than enough evidence to support I’m not the only one having a problem or who has had a problem.
If my electrical is so terrible, this issue who have popped up in the past with other gear I have used… this isn’t the first amplifier I’ve owned.
Paul, thank you so much for actually admitting this, this is the first anyone from psaudio has actually straight up explained this.
This is my exact experience. A hum/hiss that is very audible from beyond the listening position with the audible clicking. I feel like this is something that could have easily been explained to me from the beginning instead of spending hours doing tests to try and eliminate something that is inherently not going to go away. Thank you
I believe you misjudge me and my intentions here, @robbbby. In no way am I denying your experience or the experience others have reported.
Hopefully, if you read my entire post more carefully, you can see that I am simply trying to help determine the BHK amplifiers noise/hum “baseline profile” in order to determine whether you are getting a normal response from your kit or experiencing something else.
I am not an irrational PSA “fan boy”, nor am I naive enough to not understand manufacturers tend to paint their products in the best light. That said, I think my inquiry of Paul AND his response is helpful, not antithetic to your plight.
You may disagree.
Given the apparent hostility toward PSA and me that I sensed in your most recent response to me (sorry if I misread between the lines), I am taking a step back now in this thread and will not actively try to assist you in your endeavor.
[Edit: I see now that you have acknowledged Paul’s response while I was typing the above.]
This long ago left the realm of trying to get the best performance possible from the equipment and became about being right and wanting someone to admit it.
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I too ran into SE noise issues which went away on XLR with my BHK250 and BHK Pre. I have all my equipment connected to a P15 which regenerates the power.
It is good to hear Paul acknowledged that the SE is expected to be noisier but if @Paul can quantify “definite increase in noise”, hearing the noise 10+ft away is expected?
Thanks
I know that in the tube amplifier world balanced connections are not very common, but balanced cables are cheaper than RCA if you consider the benefit cost ratio. I have very reasonable priced balanced cables. Regardless how cheap the screening of an XLR, the method of separate earth and common rejection mode of balanced connection, can, if even possible, be beaten by the most expensive RCA’s only.
I do not understand how you can not utilize a balanced connection when it is available.
So, I wanted to give @robbbby the benefit of the doubt given he’s invested so much time trying to solve this. I’ve been in similar situations before and would have liked a helping hand to corroborate or refute my observation with real data.
I had a pair of SE cables lying around and decided to hop behind the rack to swap them in between the Pre and 300s from the XLR set.
The right channel went fine, similar noise profile to balanced.
To my surprise, my left channel amp started humming when I swapped in the RCA.
- I tried putting both 300s on the same P20 outlet, but hum persisted.
- Power on only amps, connected to Pre, revealed left channel hum.
- Swapped pre left and right channels. Left continued to hum.
- I disconnect the left channel RCA and the hum goes away, except when I touch the middle pin with my finger.
- I touch the middle pin to the Pre’s ground pin and there’s slight hum on right and left (checking for activity on the ground side, which there seems to be likely due to appliances, etc. I don’t have dedicated wiring yet.).
On a whim, I try connecting the left channel XLR while the RCA is connected and humming. There’s an audible click sound when I plug in the power amp XLR, repeatable–so there seems to be some kind of change when simply plugging in; no audible relay clicks though. The moment I plug in the Pre side, the hum goes away.
Given my left and right channels are behaving differently, I would say there’s something up with my left side (power amp).
The last thing I’ll try before reaching out to PSA is swapping tubes from right to left 300s. I’ll leave that for later this evening as I’ve got to go restock the bunker.
I hope you aren’t feeling too isolated now, @robbby. It seems your challenge is real.
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And you seem to want to keep stirring when none is necessary.