Is there a clear rule on when to use the 5 MA jumper setting vs stock 4 MA setting, or is it tube dependent?
darrenv1070 saidAnyone else try the red lettered standard JJ 12AU7 tubes? I was amazed at how open they sound.
Ok…I am back and sticking to the 12AU7 from JJ. Red lettered standard tube. These by a mile sound the best in my system. The most air, depth, uber quite, I will actually buy a couple pairs to to have for the long road!
Anyone interested in buy some tubes?
Hi Darren,
Couple of questions…Did you order any options with the JJ tubes, like matching or low noise? And what jumper setting do you have set for them, 4 or 5 ma? Can’t go wrong with the price.
Thanks in advance,
Dave
Dave, I ordered the JJ gold matching and low noise ( 12au7 and 6922 ). Those were more money and a touch more dry. I actually am not sure with the standard ( red lettered ) tubes. I assume these were since these were actually from a Jolida Fusion preamp modded by John Tucker. I rolled tubes in the Jolida, then sold it. I may be able to find out but I assume yes. As I type this I am listening to the system, truly amazing. I plan to buy a couple more pairs of the JJ 12au7 reds and I will post findings.
Oh with the 12au7 4 MA. I have zero luck with the 6922 in either setting
darrenv1070 saidIs there a clear rule on when to use the 5 MA jumper setting vs stock 4 MA setting, or is it tube dependent?
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.
darrenv1070 saidDave, I ordered the JJ gold matching and low noise ( 12au7 and 6922 ). Those were more money and a touch more dry. I actually am not sure with the standard ( red lettered ) tubes. I assume these were since these were actually from a Jolida Fusion preamp modded by John Tucker. I rolled tubes in the Jolida, then sold it. I may be able to find out but I assume yes. As I type this I am listening to the system, truly amazing. I plan to buy a couple more pairs of the JJ 12au7 reds and I will post findings.
Oh with the 12au7 4 MA. I have zero luck with the 6922 in either setting
I just replaced the tubes in my Manley Labs Chinook SE version ( 6922 ), removed the Philips tubes and rolled in the JJ ( red lettered ). I really like these tubes! I will roll in these tubes into my BHK 250 and report findings.
Thx Darrenv1070. Looking forward to your review of those tubes in bhk250. Wonder how those compare to the BHK select from Upscale.
Roger Macklin saidBHK here. Roger, great diligence and followup! I would like to know how to access the videos of how to change the tube current and voltage jumpers. When I finally put some 7DJ8 tubes in my preamp, I really had to look at the jumpers, think about what was to happen with changing them. I finally really looked at the nomenclature around the jumpers and realized that it is all there. Still I want to see the videos!After recommending some time ago (months) to Kevin Jackson in Customer Service and Duncan Taylor in Sales that a pictorial or video aide would be helpful for me to see the location and shift direction for the voltage and current “jumpers,” (to enable use of the Tungsram NOS 7DJ8 tubes in the BHK preamp) and recently reminding Duncan, he sent me a video where he (barehanded) pulled out the stock 12AU7 tubes and showed location and moving the voltage jumper “behind” each tube socket. When I again reminded that I had asked for similar regarding the current jumper location and shift, his response was:
"Well apologies for excluding the current jumper adjustment, but really no adjustment is needed there. In retrospect we think we could have been fine excluding the current jumper information from the manual. To date hardly any customers have been interested in tubes where the current adjustment might help.
Really the only adjustment to consider for the great majority of tubes capable of running in the BHK is the voltage jumper which I change in the video.
This includes the Tungsram 7DJ8 you want to use. Just switch the voltage jumpers like I showed you and you will be ready to listen using your new tubes."
This seemed a little uninformed or even possibly negative, so my next response included:
“I have followed the discussion thread in the PS Audio forum on the “BHK preamp tube rolling” and it is the reported consensus there that with this 7DJ8 tube (and actually any of the 6 and 7 volt tubes) the BHK preamplifier sounds better with the bias jumper(s) shifted to the 5 milliamps position(s) from the jumper position(s) for 4 milliamps.”
Duncan’s next e-mail included:
"As much as we try to keep abreast of the discussions in the forums, a large amount of it happens on a daily basis that we miss. That the tubes sound better on the higher current is news to me and the engineers! Well I’ve created a new video for you that shows where the bias jumpers are. They are in front of the tubes instead of behind them as you face the front of the unit.
I didn’t mean to imply that we’re too busy to help! Truly none of us here had heard the Tungsram tubes sound better with slightly higher bias current."
So he made a video of the bias current jumper location (and actually wore the white gloves which were showing in the background of the voltage jumper video), but this hampered moving the bias current jumpers with the tweezers.
At any rate I finally got the information requested and “closed the loop” by sending Duncan and Kevin (and Paul for his ready reference) selected posts from earlier in this thread, particularly the one from Bascom H. King (the BHK preamplifier designer!) explaining that the bias current jumper was essentially in the circuit design to allow optimum use of the 6922 family of tubes.
I removed stock PSVane 12AU7 tubes (wearing the white gloves), took off the gloves and moved the voltage and bias current jumpers for 6/7 volts and 5 milliamps settings, put the white gloves on again and installed the Tungsram NOS 7DJ8 tubes in the BHK preamp and “enjoyed the music” over the rest of the weekend: Seeming soundstage increase in each of 3 dimensions; more “air” around instruments/voices; greater timbral accuracy; fuller midrange, with excellent bass and highs.
The tube dampers and upgrade fuse for BHK preamp should come in later this week…
I will change the BHK Stereo 250 power amp tubes to the 7DJ8s and fuses soon.
Enjoying the music as the preamp tubes gain more hours…
BHK signing in here - I am surprised that the Engineers didn’t know that the 6/7 volt tubes are SUPPOSED to be run at the 5 mA setting and the 12AU7s are supposed to be run at 4 mA. This from the designer who defined these operating currents!
Roger Macklin saidterryakhan and all,
Since Duncan Taylor made me a video of the location of the voltage jumpers and how to shift them to the 6/7 volt position
and later a video of the location of the bias current jumpers and how to shift them to the 5 milliamps position,
I wanted to share the “Download attachment” "links he sent me by e-mail in hopes anyone interested could download and
view the videos to aid in replacing the stock tubes with NOS Tungsram 7DJ8 or other 6/7 volt tubes such as 6922 family.
However when cut/pasted from his e-mails, they don’t seem to work from within this post…
and
Trying the “attach” function to see if I could get them to upload indicates the .mov files sizes exceed the limit by factor of ~10 (each).
So you could e-mail Duncan Taylor (duncan@psaudio.com) and see if he would send you the same
"Download Attachment"s by e-mail.
Enjoy the music!
My earlier post on Page 4 indicated the links (to download the videos that Duncan Taylor had uploaded for me) were going to expire March 26 and March 29, 2017.
I had tried to attach those .mov files myself, so they would be available to all beyond those dates; however, as indicated earlier, each file’s size exceeded the “attachments” limit by a factor of ~10.
My previous suggestion was to e-mail Duncan Taylor (duncan@psaudio.com) to see if he would send you the same
"Download Attachment"s by e-mail.
Since they appear to have “expired,” perhaps those files should be permanently archived elsewhere on the PS Audio website where everyone who wishes to would be able to download them in perpetuity (that is, with no expiration date!). I believe I had suggested that to Duncan earlier.
I will e-mail Paul McGowan concerning this and if needed perhaps BHK could request same…
It should also be possible to add them to the PS Audio youtube channel where the BHK and Ted Smith videos are posted, I believe. Then they would just need to put links in a convenient location.
text of e-mail just sent to Paul McGowan:
Paul,
FYI, Please see the most recent posts in the “BHK preamp tube rolling” thread on PS Audio forum
http://www.psaudio.com/forum/bhk-power-and-pre-amp-forum/bhk-preamp-tube-rolling/page-5/#p71743
Would it be possible to permanently “archive” the videos which Duncan Taylor made for me (on shifting the “voltage jumpers” and the “current jumpers” in the BHK preamp (for use of the BHK-recommended Tungsram 7DJ8 tubes instead of the stock 12AU7 tubes) somewhere on the PS Audio website where everyone who wishes to would be able to download them in perpetuity (that is, with no expiration date!).
Thanks for your consideration and hopefully assistance in responding to this request.
Roger
reply from Paul McGowan:
Good call. Let me see what we can do.
Paul McGowan | CEO | PS Audio4826 Sterling Drive, Boulder, CO 80301 |
Ph 1-866-406-8946 | Fax 720-406-8967 |
Just out of the blue tonight my BHK preamp started a slight pulsing sound again. On the JJ 12au7. Odd. I even tried plugging straight into wall outlet ( not my P5 ). I disconnected ever input cable as well, just output ( XLR ). I have no idea…
Both channels? If so, did you try swapping tubes?
Yes both channels. More on one side, but yes both. I have not swapped tubes yet. It is odd, many tubes I try have this issue. Comes and goes. Maybe a unit issue! Thing is if I send into PSA and they can’t get it to do this they will ship it back.
haven’t had this happen w/ any 12v tubes. happens w/ any 6 or 7v tube I’ve tried (and I’ve tried more than a few). Sent the unit back to ps this week. we’ll see what they find - i sent it with the tungsram 7dg8 tubes in it that were pulsing in the right channel.
plugged in the PCA2 w/ the Cullen high current mod while the BHK Preamp is gone.
Guys, I have cleaned up this thread and removed all of the unnecessary quotes. Please click on “Add Reply” at the top and bottom of every page rather than quote the last post simply to reply.
Thanks!
Are tubes expected to be this finicky? I see more comments on pulsing noise than I thought I would.
Tubes typically are not finicky at all, but rather plug-n-play. I am surprised to see the multiple reports of problems.
Mark saidhaven’t had this happen w/ any 12v tubes. happens w/ any 6 or 7v tube I’ve tried (and I’ve tried more than a few). Sent the unit back to ps this week. we’ll see what they find - i sent it with the tungsram 7dg8 tubes in it that were pulsing in the right channel.
plugged in the PCA2 w/ the Cullen high current mod while the BHK Preamp is gone.
Please keep us posted on what PSA finds. I am very curious, since I have the same issue.