[googleli]

Thanks chap. Am asking because someone said adjustment should not be done at the headphone jacks.

 

[justin w.]

Quote:

Thanks chap. Am asking because someone said adjustment should not be done at the headphone jacks.

 
true, you can't adjust the headphone bias voltage at the headphone jack.  unless you use a very high input impedance meter (which you wont have)

 

[googleli]

I think what VVS posted as "be aware" is really confusing and should simply be ignored. Suggest moderator to fix that post to avoid any further confusion.

 

[tiga3mata]

Adjustment may be needed for optimal performance.  The whole reason I am hesitant to really walk people through the process is that "any EL34" tube quickly becomes "any large tube that fits in the socket" and then things start blowing up

Which is why it is good to provide clear and accurate operating instructions for equipments you supply. If owners choose not to follow your instructions then they are solely liable for any resulting consequences, I believe BHSE owners are mature enough to understand that.

I am keen to maximize the performance of my BHSE which is not unusual for owners of equipment of this calibre. Unfortunately I am not conversant with some of the technical terms used here. I have read this whole thread multiple times and received some help from kind members. But I want to be entirely sure about how to use the tool that will be included. The stock EL34 will inevitably fail so knowing the proper re-tubing procedure is a necessity.

I am a supporter making a reasonable request for help on how to properly operate a Headamp product. Your effort will be much appreciated.

 

[David1961]

Like an Headfier suggested, I think the absolute easiest and best way to know how to change tubes on the BHSE, is for someone to do a video and show it on youtube.

 

[TheAttorney]

So, in the absence of a proper instruction booklet, the way I see it...
 

1. If you want to tube roll to a different EL34 (or the similar KT77), then all you need to do is adjust the "DC balance and offset", which you do by inserting your multimeter probes into the front headphone socket, and using the trim screwdriver thingy to make the adjustments through the top slots. All without opening anything.
2. Same if you want to periodically check that your existing EL34 tubes haven't drifted over time.
3. VVS' adapter tool thingy seems an overkill for this task - he only needs to do that because his particular multimeter probes are of the locking variety and therefore too big to slide into the headphone socket. A simpler solution would be to get the thin pointy type of probe, which most multimeters come with anyway.
4. If you never do this adjustment to your existing tubes, it's not the end of the world. Everything keeps on working for years, but maybe not at 100% optimum performance.

 

1. You only ever need to adjust the "bias voltage" if you're an advanced tube amp user, or a lunatic, or spritzer (because he's like that). There is no reason whatsoever for normal users to ever adjust the bias voltage. But if you really want to do that, then you have to do that at the power supply, and be prepared to meet your maker.
2. You shouldn't replace the EL34 with any other tube model (apart from maybe the KT77). You would only ever want to do this if you're an advanced tube amp user, or a lunatic, or spritzer (because he's like that). And be prepared for you or your amp to meet your respective makers.

 
Edit: Corrected KT88 to KT77

 

[Asr]

^ Correction: only KT77 tubes will work in the BHSE. KT88s will probably cause "you or your amp to meet your respective makers".

 

[justin w.]

Quote:

Like an Headfier suggested, I think the absolute easiest and best way to know how to change tubes on the BHSE, is for someone to do a video and show it on youtube.

 
i agree, and i will make a video, post it to youtube, and put the link in the documentation.

 

[David1961]

Quote:

 
i agree, and i will make a video, post it to youtube, and put the link in the documentation.

That's great news Justin, Thank you !

 

[spritzer]

I know the BH design well enough to never use any other tube but the EL34.  The 6CA7 and KT77 are similar but the old Mullard's are still the gold standard.  KT66, KT88, KT120, 6550, 3D21A. 3D21W, 6BG6GA etc. etc. etc. will not work.  People have tried and blown up the amp.  Some have even managed to remove the tubes while the amp was running and blown it up.  

 

[David1961]

Quote:

  Some have even managed to remove the tubes while the amp was running and blown it up.  

 
Those that have done that must have had asbestos hands, while the chassis gets nice and warm the tubes do get quite hot.

 

[TheAttorney]

Quote:

^ Correction: only KT77 tubes will work in the BHSE. KT88s will probably cause "you or your amp to meet your respective makers".

Oops! I've corrected my earlier post. Best not to further confuse readers.

 

[David1961]

I've just placed an order for a quad of SVETLANA/WINGED ' C ' Cryo valves which I was going to use as backup, but seeing Justin is kindly doing a video showing how to change the tubes on the BHSE, I might aswell try them after I seen that video.

 

[googleli]

Quote:

I know the BH design well enough to never use any other tube but the EL34.  The 6CA7 and KT77 are similar but the old Mullard's are still the gold standard.  KT66, KT88, KT120, 6550, 3D21A. 3D21W, 6BG6GA etc. etc. etc. will not work.  People have tried and blown up the amp.  Some have even managed to remove the tubes while the amp was running and blown it up.  

 
Thanks Spritzer - I will try to look for NOS Mullards.

 

[forbigger]

Quote:

 
Those that have done that must have had asbestos hands, while the chassis gets nice and warm the tubes do get quite hot.

^^ bet this can be done. in the beginning when the amp is turned on.