I don’t get it either. I have to go right up to the speakers with my ear very close to the midrange drivers to hear the noise and my speakers are efficient 93 db per watt. No I am not hard of hearing!
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Paul told me, that was to be expected with high efficiency speakers.
The whirlwind attenuators have not affected the SQ at all. I actually bought them a couple of months ago, but, I was apprehensive about putting them into my system. Turns out, my concerns didn’t bear out.
Thats good you are not hearing sound quality issues.
It is quite normal to hear tube hiss when placing ears up against the speakers. The issue is how loud the hiss is a listening position.
The quality attenuators on the market are designed by people who specialize in reducing gain without affecting sound quality. The ones from Rothwell for example are built by a company that specializes in MC phono preamps and SUTs. Others are built by companies selling to the recording industry. The ones like the Harrison’s sold on places like Parts Express were designed for the car audio market. Which one you will be happiest with depends on your expectations.
I tried the Harrisons and they were terrible. The Sys passive pre is great since I can adjust the volume to perfect levels.
This arrived a just 3 days ago and I’m so happy.
I saved up and bought it after reading many positive reviews and borrowing a demo unit from my local dealer. Also because I agree with the technical concept behind it and with what @Paul and @BHK were trying to achieve.
I feed it clean power from a P12. I hooked it up to my system, switched it on and wow! Amazing sound right out of the box!
I haven’t switched it off to burn it in. The power amps are off, though. Just a DS Sr and the BHK preamp are on, playing music continuously.
Two and a half days later, I’m here:
The sound just keeps getting better and better! More holographic imaging. More bass definition. Smoother midrange. Highs are nice and airy.
My question is, how many more hours of break-in does it need before I no longer hear changes (improvements) in the sound? 
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@Leonard - I got my BHK PRE in Jan, 2019 and it took about 400 hrs before it settled in terms of no changes. Relax and enjoy the ride… it sounds great out of the box and it just gets better and better. Then roll some new tubes and another bump… then add a different set based on your preference for sound and just enjoy the ride… I also added dampeners when I took the new tube bump and it sounds great…
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I have close to 200 hours on mine and it’s still going through its changes.
Congratulations. I don’t know an exact answer to the question because the BHK is like a fine wine, it just keeps getting better with time. However, I would think the biggest changes have already taken place and now you’re in for a bit of polish every time you
listen. Have fun!
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Thanks, @Paul. I listen when I get home after work and the BHK Preamp sounds fantastic! It sounds so good, I’m wondering if I should tube roll at all. The BHK Pre actually my first tube anything!
The jumpers beside the tubes do encourage rolling, so I may try it sometime in the future.
Is there an official guide from PS Audio as to which tubes are recommended for the BHK Pre and what changes in sound quality they will result in? For example, if one wants more highs while maintaining everything else (sacrificing nothing), what tubes will produce this effect?
I am asking because I know some folks who who disagree on the sonic flavors of various tubes, maybe because of how their equipment actually uses those tubes. I was told a tube that bumps up the bass in a certain preamp can actually reduce it in another. So, advice on a certain brand or type of tube should be taken with a grain of salt.
It there isn’t an official PS Audio guide, would there, by any chance, be a list of tubes and the corresponding flavors they result in, based on feedback from BHK Preamp owners who have used those tubes? Thanks in advance.
There is no repository of specific tubes. I find that the on line reviews of the 6DJ8, 7DJ8, 6922, 12AU7’s will get you started. If you use 12 Volt tubes instead of 6/7 Volt tubes, the jumpers need to be configured correctly. My favourite tubes for BHK Pre: Philips 6922 PQ/SQ, Philips 7DJ8 Miniwatt’s and Telefunken 12AU7’s
There’s a thread for tube rolling in the BHK preamp here:
https://forum.psaudio.com/t/bhk-preamp-tube-rolling
While not official, there are a plethora of tube choices and opinions to sift thru.
I agree, the BHK preamp is superb sounding.
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Watchdog, are the Telefunken’s the current production Black Diamonds? I’ve narrowed down my next set to these or the Genelex.
I use no current manufacturer tubes. New Old Stock only. The Genelex are OK but easily bettered. 12AU7 are cheaper than 6DJ8/6922/7DJ8. I like the Diamond base Telefunken tubes. These are 10,000 hour tubes so once you find one you like, the long term investment costs are low.
Thank you @watchdog507 and @davek. I have friends who have been tube-rolling for decades and they guard their stash like wives guard their jewelry, especially since many of those tubes are now “unobtanium.”
For certain older gear from brands like McIntosh and Audio Research, I was told there are guides that list compatible tubes by sonic characteristics, price, and availability. There is a vetting process for a tube to be included in the guide. For example, a certain number of people must hear it in their systems and agree on those aspects. Also, unreliable sellers (those who say “unused” on tubes with thousands of hours in them or those who say “matched tubes” when in fact they are not) are removed from the guide. Some guides even include the year, batch, and a photograph of the tube and the box it came in, so that there is no room for misunderstanding and fakes are avoided. Also, tubes that are especially difficult to find or especially expensive in a separate section. Then one can decide on one’s own whether or not to chase after them.
I suppose those who contributed to the guide want fellow owners to save time and money and take “YMMV” (your mileage may vary) out of the equation.
No more "Tube XYZ added bass in my system but it may not in yours."
No more "Tube 123 made improved my midrange but added noise (tube rush)."
No more "Tube ABC made it sound heavenly but I have the last pair ever made."
Perhaps one day a similar guide can be compiled for the BHK preamp and power amps.
There’s certainly no official guide published by us and I run the stock tubes in mine. There’s plenty of folks who think differently and this forum’s a great place to connect with them.
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What power cord are you using on the pre?
Triode Wire Lab’s 7+ though the 10+ would be more than enough.
If it 'aint broke, don try fix it.
When BHK pre owners are in to tube rolling, how does that affect the behavior of the “tube time” counter? Is “tube time” just a total time in service counter for the pre-amp i.e. it’s not counting a burn time on a particular tube set? The counter just keeps ticking over cumulatively even after a new set of tubes is installed?