[harris4crna]

After 7 month bhse returned to me repaired! No comment! I already sell the amplifier, I think that a inefficient support like this is not justified for an amplifier that cost about 6k usd !

Trust is one thing, but 6 month wait for a repair is plainly unsat. I hope my BHSE does not need to be repaired. Now, I am paranoid even to change out tubes for screwing it up.

Now, a newbie like me. Do you have to bias the amp every time you change tubes? Dan Clark praises the EL 34 Siemens up and down for the Voce, perhaps I would give them a try if I ever decide to complement my Stax 009.
Thank you

 

[harris4crna]

Another question, for the past 6 months I have been running my source equipment through my preamp. From my preamp I output to the BHSE. Other than volume management, does anyone foresee an issue with this?

Why am I doing this?

Ease of selection between sources with using balanced (XLR) inputs/outputs. Peter recommended I use balance inputs for the BHSE. If I don’t use the preamp than I’m forced to physically attach sources manually every time I listen. Pain in my current setup.

Thoughts

 

[daytrader]

Trust is one thing, but 6 month wait for a repair is plainly unsat. I hope my BHSE does not need to be repaired. Now, I am paranoid even to change out tubes for screwing it up.

Now, a newbie like me. Do you have to bias the amp every time you change tubes? Dan Clark praises the EL 34 Siemens up and down for the Voce, perhaps I would give them a try if I ever decide to complement my Stax 009.
Thank you

My guess, unless the unit has auto-biasing and I think not, is you will have to re-bias with each power tube change. Yeah not good when these types of customer service stories come out. Good luck.

 

[TheAttorney]

My guess, unless the unit has auto-biasing and I think not, is you will have to re-bias with each power tube change.

It's better not to guess. The short answer is that you do not need to make any bias adjustments after a BHSE tube change, but it's worthwhile to measure with a multimeter just in case one of the new tubes is faulty or way out of spec. And wait at least 1 hour's warm up before measuring. There's a YouTube video about how to measure. For a longer answer, I've copy and pasted an old post below...

People here have used the term "bias" rather loosely to mean the balance and offset adjustments. But strictly speaking the bias is an internal adjustment set by Justin and which you can forget about unless (a) you really, really know what you are doing (i.e. a tube amp designer), or (b) you are recklessly stupid.

Of the external user adjustments, I don't think which is which has been formally stated, but I assume "balance" refers to the difference between + and -, and "offset" refers to + and ground. Both of these have the same "exponential curve" characteristic whereby they start off with a big difference at cold, initially quickly slide towards zero, the rate of progress reducing as zero approaches. Most of the slide has happened by 1 hour, but it continues sliding right up to 3 or 4 hours. As the Offset difference is an order or magnitude higher than Balance, its best to focus on that when measuring (the latter just needs an occasional check, but largely takes care of itself). The Offset adjustment is also more prone to a kind of hysteresis effect, i.e. nothing seems to happen as you turn the pot, then it suddenly overshoots. Even if you get it to zero now, it will probably drift a couple of volts tomorrow. This is all normal, but can keep OCD types amused for hours, or you can just not worry about a couple of volts..

The same applies to existing or new tubes. So there is no value in messing up Justin's original settings if you're putting in new tubes and adjusting after say 1 hour. All you need to do is use a voltmeter to check that the new tubes are following the same exponential curve. If at any time they are heading in the right direction, then leave them alone. Wait until the rate of change becomes insignificant, by which time you will find that the new tubes are magically close to the old ones. so no adjustment is needed. If the new tubes do not broadly follow the same curve, then there may, or may not, be a problem that needs further investigation.

 

[daytrader]

It's better not to guess. The short answer is that you do not need to make any bias adjustments after a BHSE tube change, but it's worthwhile to measure with a multimeter just in case one of the new tubes is faulty or way out of spec. And wait at least 1 hour's warm up before measuring. There's a YouTube video about how to measure. For a longer answer, I've copy and pasted an old post below...

People here have used the term "bias" rather loosely to mean the balance and offset adjustments. But strictly speaking the bias is an internal adjustment set by Justin and which you can forget about unless (a) you really, really know what you are doing (i.e. a tube amp designer), or (b) you are recklessly stupid.

Of the external user adjustments, I don't think which is which has been formally stated, but I assume "balance" refers to the difference between + and -, and "offset" refers to + and ground. Both of these have the same "exponential curve" characteristic whereby they start off with a big difference at cold, initially quickly slide towards zero, the rate of progress reducing as zero approaches. Most of the slide has happened by 1 hour, but it continues sliding right up to 3 or 4 hours. As the Offset difference is an order or magnitude higher than Balance, its best to focus on that when measuring (the latter just needs an occasional check, but largely takes care of itself). The Offset adjustment is also more prone to a kind of hysteresis effect, i.e. nothing seems to happen as you turn the pot, then it suddenly overshoots. Even if you get it to zero now, it will probably drift a couple of volts tomorrow. This is all normal, but can keep OCD types amused for hours, or you can just not worry about a couple of volts..

The same applies to existing or new tubes. So there is no value in messing up Justin's original settings if you're putting in new tubes and adjusting after say 1 hour. All you need to do is use a voltmeter to check that the new tubes are following the same exponential curve. If at any time they are heading in the right direction, then leave them alone. Wait until the rate of change becomes insignificant, by which time you will find that the new tubes are magically close to the old ones. so no adjustment is needed. If the new tubes do not broadly follow the same curve, then there may, or may not, be a problem that needs further investigation.

“but it's worthwhile to measure with a multimeter just in case one of the new tubes is faulty or way out of spec. And wait at least 1 hour's warm up before measuring.” - Sounds like a bias adjustment to me! OCD amusement notwithstanding.

 

[jhellow]

It's better not to guess. The short answer is that you do not need to make any bias adjustments after a BHSE tube change, but it's worthwhile to measure with a multimeter just in case one of the new tubes is faulty or way out of spec. And wait at least 1 hour's warm up before measuring. There's a YouTube video about how to measure. For a longer answer, I've copy and pasted an old post below...

That is all but the adjustment part of a bias adjustment. I do an adjustment at about the 10 minute mark to make sure nothing is off by multiple volts, then again at two hours to dial everything in. When I did this last set of XF2s, the next day they were within .1 volts of zero on a check.

 

[TheAttorney]

Sounds like a bias adjustment to me!

No it's not an adjustment. I said it's worth measuring just in case. But in practice of a number of different new and vintage tube swaps, absolutely none of them required me to make any adjustments - i.e. after a couple of hours warm up, all of them ended up within a single digit volt reading. And other posts in this thread have also stated that they did not need to do bias adjustments.

As it happens, I did sometime make adjustments because it was fun and my OCD nature wanted to see if it was possible to get to a fraction of a volt, but ultra low readings were largely pointless because the voltage would naturally drift slightly by the next session. I did feel that a very low voltage reading did seem to slightly improve SQ compared to several volts, but that was an informal subjective impression.

I only posted to correct the notion that tube swaps must include bias adjustments. It isn't strictly necessary, but it's always worthwhile to measure just in case the next swap is the exception that proves the rule. All this applies only to my experience of the BHSE - different tube amp designs have different requirements.

 

[jhellow]

I have only done 4 tube swaps on the BHSE, but in every instance several volts needed to be adjusted out, most of it after the first 10 minutes. The follow-up adjustment at 2 hours usually involved getting the last volt to zero or close to it.

 

[TheAttorney]

I have only done 4 tube swaps on the BHSE, but in every instance several volts needed to be adjusted out, most of it after the first 10 minutes. The follow-up adjustment at 2 hours usually involved getting the last volt to zero or close to it.

Ok, this is my final post on this topic:

IMO, it is a mistake to make an adjustment in the first few minutes. At this point the voltage readings can be rather high, say 40 - 60v.
When measured at this point, the tubes typically have a bigger difference between themselves. Say 3 tubes read 40-45v and 1 tube reads 50v, so it's tempting to adjust down that 4th tube. But if you just left it alone, you will probably find that the 4th tube's voltage drops at a faster rate than the others and all of them end up fairly close after a couple of hours, say all within 2 - 5v. At least that has been my experience.

So IMO making adjustments from cold are not only unnecessary, they may well change a setting that was perfectly fine to start with.

Look, everyone's mileage varies, and if you enjoy fiddling round with bias adjustments then that's perfectly OK. I'm just suggesting a simpler way for those who don't want to continually mess around with this sort of thing. Now, had 3 tubes read 40 - 45v and the 4th read 150v, then I'd be very concerned, but that never happened to me.

Absolutely my final post on this topic. I'm only here for nostalgic reasons for one of my most favourite hifi components that I've ever owned

 

[daytrader]

No it's not an adjustment. I said it's worth measuring just in case. But in practice of a number of different new and vintage tube swaps, absolutely none of them required me to make any adjustments - i.e. after a couple of hours warm up, all of them ended up within a single digit volt reading. And other posts in this thread have also stated that they did not need to do bias adjustments.

As it happens, I did sometime make adjustments because it was fun and my OCD nature wanted to see if it was possible to get to a fraction of a volt, but ultra low readings were largely pointless because the voltage would naturally drift slightly by the next session. I did feel that a very low voltage reading did seem to slightly improve SQ compared to several volts, but that was an informal subjective impression.

I only posted to correct the notion that tube swaps must include bias adjustments. It isn't strictly necessary, but it's always worthwhile to measure just in case the next swap is the exception that proves the rule. All this applies only to my experience of the BHSE - different tube amp designs have different requirements.

If that’s how Justin has set up the unit then it is what it is, so I get it and nice to have clarification. My tube amps have always seemed to have bias circuitry used, to prolong and better sq, auto or self, in all my power amps. This is why I phrased my response as a guess. My response was in general but as not having owned a BHSE, I will assume the poster would contact the manufacturer and get a verification response back, which rightfully concerned him as has others here on the site. BTW, I have purchased from HeadAmp so understand his trepidation. I live in NOVA where HeadAmp is currently located and the virus certainly has slowed things down considerably would be my take on things.

 

[makan]

Wondering if someone could let me know the exact length of the umbilical cable that comes headamp BHSE? Thanks

 

[tumpux]

One meter-ish..

 

[Bonddam]

This option is available but am not familiar with tubes. Read through page 6 of this thread. Have the BHSE on order. Are these good?

The 1960's and 1970's Mullard EL34 has become the benchmark of all EL34 and there's a reason for it. These EL34 are known for an incredible bottom end, pronounced liquid mids and exceptional highs. These are the Mullard XF2, XF3 & XF4 models with single O getter. Labeled Mullard, Siemens, Philips and other brands in original boxes, these EL34 are authentic Mullard (Blackburn, England).

 

[jhellow]

This option is available but am not familiar with tubes. Read through page 6 of this thread. Have the BHSE on order. Are these good?

The 1960's and 1970's Mullard EL34 has become the benchmark of all EL34 and there's a reason for it. These EL34 are known for an incredible bottom end, pronounced liquid mids and exceptional highs. These are the Mullard XF2, XF3 & XF4 models with single O getter. Labeled Mullard, Siemens, Philips and other brands in original boxes, these EL34 are authentic Mullard (Blackburn, England).

I use single “O” getter XF2s, and so far of the 4 tube types I have tried these sound the best. Are you indicating that Justin has made NOS XF2s available as an option with your BHSE order?

 

[Bonddam]

I use single “O” getter XF2s, and so far of the 4 tube types I have tried these sound the best. Are you indicating that Justin has made NOS XF2s available as an option with your BHSE order?

No Justin hasn’t made this available I went to tube depot after researching xf2 on google. Not sure I want to mess with bias, don’t know how to do it.