Jack43, actually I was wondering what Sirius/XM receiver you were using. Should have been more specific …
Hopper–I get Serius XM on Dish
Really? Did not know that. Thanks for enlightening me!
Can you use 6h30 tubes?
Jtsnead said Can you use 6h30 tubes?No, I already asked, and they won't operate in the BHK in their nominal linear 'sweet spot.' Meaning, the output will be nonlinear based on what goes in. So no, you don't want to use 6H30's. Which is a bummer as I have two spare sets that I hadn't used yet for my AR LS26.
–SSW
BHK said The intent of the bias or tube operating switch was to allow for the use of the 12AU7 and the 6922 family of tubes. For the 6922 types, the current was set for 5 mA and for the 12AU7, 4 mA. It would be interesting to see what you think of the sound when set at 5 mA vs. what you observed when set at 4 mA, the factory setting for the 12AU7.This needs to go into the user manual, namely, for 12V tubes, set current at 4 mA, for 6V tubes, set at 5 mA. Looking at the manual I'd never have known this. Fortunately I remembered this when I put in the Tungsrams Sunday.
–SSW
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The manual should also specify which tubes are acceptable. It seems that it is just 12AU7’s and 6922/6DJ8/7DJ8’s but I’m still not entirely clear on that (e.g., if other 12 series tubes might work, such as 12AX7’s or 12AT7’s, both of which I have spares for other equipment).
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stevem2 said The manual should also specify which tubes are acceptable. It seems that it is just 12AU7's and 6922/6DJ8/7DJ8's but I'm still not entirely clear on that (e.g., if other 12 series tubes might work, such as 12AX7's or 12AT7's, both of which I have spares for other equipment).12AX7's definitely won't work. 12AT7s might work. It really is best to stick to 12AU7s or their equivalents.
Thanks Bascom. I didn’t really expect that the other 12 series tubes would work (or, if they did, be recommended) but was curious. I’m sticking with the 7DJ8’s for the foreseeable future but it’s good to know. It would be helpful if PSA revised the manual to specify 12AU7’s and 6922’s and equivalents only, with the correct jumper settings.
I replaced my tubes today with 7DJ8’s, changed both filament and bias jumpers, but I hear a low level pulsing sound all the time and a static/clicking when adjusting volume. Hear in both channels, Sq is is on bright side. Can’t be right. Anyone any ideas, defective tube ?
The pulsing sound is weird and I have no insight to offer; hopefully others will. Are you using the Tungsram tubes or some other brand?
The click when changing volume has been discussed here; it is something that the BHK pre does. (When I have time I will post more thoughts about that and a couple of other functionality issues with the pre.) I find that the clicking is much lower in volume, almost inaudible, when I switch from an RCA to an XLR interconnect between the pre and BHK 250 amp. I have not noticed any change when installing different tubes. So I wouldn’t worry about the clicks.
magister said The pulsing sound is weird and I have no insight to offer; hopefully others will. Are you using the Tungsram tubes or some other brand?Yes they are Tungsram's from Upscale, the premium cryos. I did not hear the pulsing at first, it's sometimes masked by the music, but it may have increased in loudness during the hour I used the preamp. I've turned it off thinking maybe there was a serious problem and the sq as I said is not very good so wasn't enjoying it anyway, doubt if it's break-in sound. I'm using balanced ICs. Guess it's not a defective tube as both channels are affected.The click when changing volume has been discussed here; it is something that the BHK pre does. (When I have time I will post more thoughts about that and a couple of other functionality issues with the pre.) I find that the clicking is much lower in volume, almost inaudible, when I switch from an RCA to an XLR interconnect between the pre and BHK 250 amp. I have not noticed any change when installing different tubes. So I wouldn’t worry about the clicks.
Does the clicking occur with the stock tubes also ? Mine is only with the Tungsrams.
I got the clicking with the stock tubes, not loud but definitely noticeable (as others have described). Less audible with the XLR interconnects. Then I installed the PCC88s, no change in the clicking.
Well tonight no pulsing noise, yes weird.
Interesting. Approx 50 days in, the BHK pre is definitely breaking in. I was playing vinyl today, and the sound was absolutely gorgeous. Smooth, open, REAL (even at low volume).
I am prompted to write based on the fact that volume control noise has not called any attention to itself in a while. When I read the last post here, I did a quick check – no noise at all. I’m using the tungsrams (80 hours) and balanced interconnects.
So, all i can say is patience, patience…
Yes, things are still breaking in here as well. I didn’t install the Tungsram tubes until my BHK pre had well over 100 hours on it, and now the tubes themselves have 120 hours (thanks for that nifty tube hour counter, Paul!). Even now I am continuing to hear improvements, subtle but real; whether it’s the pre, the tubes, or both I can’t say.
I wasn’t a part of the preamp beta testing, but I did read the posts and remember the comments about the clicking. I don’t believe that there were any comments from Paul or BHK to the effect “Don’t worry, the clicking will go away with breakin.” So I’m not sure what to think about this. With my unit, the clicks are even less audible than they were after I switched to the XLR interconnects a few weeks ago. I can still hear them if I listen very attentively.
I’m in a wait and see mode, if the pulsing returns/remains I’ll have to remove them. The clicking can be rather loud with the initial volume adjustment but I could live with it. But while the sq is improving its still too much on the lean side for me. But I’ve only got 15-20 hrs burn time.
For what it’s worth, I ordered 4 of the tungsrams from upscale and with two of them in the BhK I heard a loud pulsating noise. It was more like tube rush, I initially thought that the tubes needed breakin. 30 hours later noise didn’t go away. Changed in the other two, and the noise was gone. So looks like they were defective tubes.
My pulsing is iintermittant, it was gone for two days, just when I thought it was fixed it returned and last night was gone again. And the last time it was only from the left channel. Sq with the pulsing is bright and lean, last night very good so yes it must be defective tubes. I wrote Upscale using their site Contact but haven’t received a reply after five days, poor customer service I’d say. Guess I’ll have to call.
I’ve heard the pulsing with two sets of Tungsram 7DJ8 platinum/cryro tubes from Upscale. In both cases it was only one tube in the set - I could swap tubes and the pulsing would swap channels. Reseating and straightening pins had no effect. The pulsing started after 200-300 hours in both cases. I called Upscale when it happened the first time and they sent me a replacement.
Since I’d ordered 2 sets from them originally I started using the second set when the first set had the one tube get funky. Then the pulsing started happening w/ the second set. Same deal, swapped tubes in the preamp - pulsing changed channels. Called Upscale, spoke w/ Kevin and sent both suspect tubes back to Upscale. Caught up with Kevin a few weeks later and he tells me both tubes tested fine. He’s scratching his head - all I can tell him is they don’t sound fine… He sent me a replacement tube for the second tube.
The original tube from the first pair and its replacement are still in the preamp w/ probably 700 hours on the original and 400 hours on the replacement. No problems - sounds great. This is in a beta preamp w/ 1.0.4.2 firmware.
So definitely call them - this was my first time dealing with Upscale - I thought they were very responsive and easy to deal with.