BHK Signature 250 or 300 Tube Rolling

Mark A. Larsen said Elk, we can agree to disagree. You apparently have not rolled your tubes. Without doing so, you may underestimate the overall impact.
My position does not arise out of ignorance. Changing tubes can have a minor to major impact, both good and bad. No one disagrees that this is the case.

Rather, I do not expect a review to make a point of this merely because a piece of kit happens to incorporate tubes. I similarly of do not expect every review to mention swapping wires, incorporating vibration control, etc. These are simply tweaks of which all hobbyists should already be aware.

Mark A. Larsen said

I thought once I found a set of quads I liked in my system, tube rolling came to an end. With the Redcloud update, the Siemens ECC88 and the Tungstram sounded shrill. The top end was too hot. I am back to the Amperex (Holland PQ).


Mark,

You might want to check with PSA support to see if they will work, but I have found Western Electric 396A and 2C51 tubes with a 5670 to 6922 adapter to be superior to any 6922 family tube I tried. That included Siemens CCa, Telefunken CCa, and several years of pinched waist Herleen tubes. On top of that, they are still relatively inexpensive.

I just changed to RCA 6922/E88CC tubes, which are “Made in Germany” by Siemens. I think I have reached a final choice. Elk, what do you think given your own tube rolling?

Mark, where did you purchase your Siemens RCA 6922? Thx.

I finally installed the Tungsram PCC88 over the holidays and can say I am quite please with the results.

A friend gave the Siemens RCAs to me. They are tightly balanced, say 1% to 2%. The Tungsram also are a good choice.

Mark,

How much better are the Siemens compare to the Tungsrams?

Hi everyone!

Does anybody here have experience with the Reflector 6H23p-EB tubes in BHK 250 / 300?

Thanks in advance.

For my BHK preamp I am looking to add some warmth and gain. Any suggestions on tube swap for this? My amp is a 45 SET and it could use a bit more gain. It is also very detailed. My Speakers are Altec 604-8G’s which are on the bright side. So I am getting a bit too much detail/brightness if you know what I mean.

TIA

Here is a tube rolling tip for the family! I switched to Tungsram PCC88 / 7DJ8 tubes in October of 2016 for both my BHK pre and stereo 250 amps. At the time I bought 4 pairs so I would have a back up pair if they worked out. They sounded great in my system and the tubes were trouble free for 15 months and 3200 hours. Last week I decided to swap them out for my backup pair of Tungsrams. After installing the new pairs, I heard a very loud clicking noise from the left channel when adjusting the volume of my BHK pre. I let the tubes burn in for 21 hours and the loud clicking noise got louder! The advice from my tube seller was to switch the left pre amp tube out with the left amp tube. Since they were matched pairs, I switch out both pairs of tubes. My system is sounding better than ever. The loud clicks are gone.

Paul and/or Bascom, is there a specific attribute or quality required of the BHK pre amp’s tubes to avoid loud clicking noise from the volume cotrol?

A number of users have reported various noise problems with the Tungsram 7DJ8’s in the BHK Pre. I was one of them (although I’ve forgotten exactly what the issue was). Since, as established elsewhere, I rarely throw tubes out, the next time I replaced my tubes I put the troublesome tube (and its matched mate) into my Classic 250. 350 hours later they still sound great. No idea why the BHK Pre is fussier than the Classic 250.

stevem2 said

A number of users have reported various noise problems with the Tungsram 7DJ8’s in the BHK Pre. I was one of them (although I’ve forgotten exactly what the issue was). Since, as established elsewhere, I rarely throw tubes out, the next time I replaced my tubes I put the troublesome tube (and its matched mate) into my Classic 250. 350 hours later they still sound great. No idea why the BHK Pre is fussier than the Classic 250.


The reason that the preamp is more fussy about tubes is that there is a servo in each channel to keep the cathode voltages of the two halves of the tubes at the same DC potential. When the two halves of a tube get too far different from each other, the servos can’t bring the voltages to equality and pops occur when changing volume. Sometimes when it seems that there are severe pops with a pair of tubes, as I have mentioned before, swapping the tubes sometimes helps. This is because putting the “bad” tube in the other channel’s servo frequently will work OK.

1 Like

Someone really needs to ry some Western Electric “JW” 2C51 tubes or WE396A tubes in adapters. I have found these tubes to be much better than all but the best 6922 tubes…and they are arguably better than them too.

rromeo923 said

For my BHK preamp I am looking to add some warmth and gain. Any suggestions on tube swap for this? My amp is a 45 SET and it could use a bit more gain. It is also very detailed. My Speakers are Altec 604-8G’s which are on the bright side. So I am getting a bit too much detail/brightness if you know what I mean.

TIA


Well it seems that the BHK needed some more breakin time. That post above was at 40 hrs and I was not happy at how harsh it was sounding. Now at about 60 hrs and sounding much better. I understand 200 hrs is the breakin period. I never was a big believer in this type of thing but now I have to say it is a real thing. I will wait till I start rolling some tubes…

Oh yeah, break in is a real thing, and you are right to give it at least 200 hours before working on system voicing. Once there, there are lots of tube variants to try, and that is one of the glories of tubed gear - - better system matching.

Speed Racer said

Someone really needs to ry some Western Electric “JW” 2C51 tubes or WE396A tubes in adapters. I have found these tubes to be much better than all but the best 6922 tubes…and they are arguably better than them too.


BHK,

Any problem using this adapter in the 250 or 300 amps?

BHK’s post here should be of interest to you.

a25105 said

How much better are the Siemens compare to the Tungsrams?

It is a great question without a very satisfying answer. I think it is system specific. With that caveat, the RCAs are rebranded 1964 Siemens 6922/E88CC made in Germany, considered by many as the holy grail. They are much better, in my system as currently configured, than anything else I have tried. The RCAs have much better top end (smoother), a deadly accurate mid-range, and a tight, deep bass.

As as someone new to tubes, and thus tube rolling, I have a few questions regarding buying NOS tubes. What are the specs one should be mindful of? Any recommended vendors? Have any of you had good experiences on EBay?

It looks like the RCA 6922 tubes are about $60. Is that a reasonable price?

Thanks.

Mark,

Is this the same 6922 that you are referring to?

https://www.upscaleaudio.com/products/siemens-a-frame-e88cc-6922