[David1961]

Quote:

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

Yes I guess it could be done when the BHSE's first powered up, but still a daft thing to do even when cool.

 

[spritzer]

Do not remove the tubes until the amp has fully cooled down and the PSU has fully discharged.  Also I would only buy tubes from reputable sellers and stay away from ebay unless you have a good tube tester at home. 

 

[David1961]

When I mentioned the BHSE only gets above warm, I'd only had it on power for about one to two hours. Today I had it on for over five hours continually and it did get hot, I was still able to put my hands on it but like I say it did get hot. However in that time it work flawlessly and the music I was hearing was utterly outstanding.

 

[ericohgb]

Do not remove the tubes until the amp has fully cooled down and the PSU has fully discharged.  Also I would only buy tubes from reputable sellers and stay away from ebay unless you have a good tube tester at home. 

Dear Spritzer,
When changing for incorrect or damaged tubes, what can be damaged, the tubes or the amp itself? I recall changing my WES EL34 for damaged Mullards. It just didn't output any sound.
I guess this procedure of changing tubes gotta be more careful when talking about the BHSE.

Other common mistake is thinking that a KT88 can be used in the BHSE. I guess it started because unadvertised WES owners like me have the possibility to use them and therefore
Think that any EL34 amp can use KT88...

Thanks
Erico

 

[googleli]

Recently I found a genre of music which I like a lot. I thought I am only into jazz, jazz vocal and some pop. This changed my mind.
 
http://www.dj-kicks.com/tag/digitalism/
 
This is the kind of music on which I prefer the 009 way over the LCD3. Bass goes deep but crisp clear and not slow/shallow. Now I miss my pre-RMAed LCD3, which had really good bass. My current LCD3 just does not have enough weight (although it is very good compared with many other headphones). I will certainly try the CD again with the BHSE. Anyone has some good recommendations for similar music? Thanks.

 

[spritzer]

Quote:

Dear Spritzer,
When changing for incorrect or damaged tubes, what can be damaged, the tubes or the amp itself? I recall changing my WES EL34 for damaged Mullards. It just didn't output any sound.
I guess this procedure of changing tubes gotta be more careful when talking about the BHSE.
Other common mistake is thinking that a KT88 can be used in the BHSE. I guess it started because unadvertised WES owners like me have the possibility to use them and therefore
Think that any EL34 amp can use KT88...
Thanks
Erico

 
The WES and the BHSE really couldn't be more different in this regard.  The WES could have been made in the 1940's so if you insert the wrong tube (assuming it is at least similar in pinout) or a damaged one you overload the stage and the cathode resistor starts to smoke as it is asked to pass too much current.  While the circuit is designed for some tube in mind there is so much tolerance built in (or rather the design isn't specific enough) that other tubes with similar spec can be used.  Now this doesn't mean the tubes should be used though.  Just because something makes sound doesn't mean it is working well... 
 
The BHSE on the other hand could not be serviced by a tube tech from the 50's.  In fact most of it would make no sense to him as it really is an all solid state amp which simply uses tubes for the output as they are the best part for the job.  No single solid state part can replace the tubes and do as good a job.  Now the circuit is setup for the EL34's in mind and there are no large resistors here, all the operating points are set by transistors.  If the wrong or defective part were to be installed the first parts to go would probably be the cathode mosfets as they would overheat and explode.  That's not something which is easy to fix so best not do that... 
 
You do bring up a good point though that people view amps with similar tubes as being similar when it couldn't be further from the truth.  Take two electrostatic amps, the WES and ESX (the fixed version of the Single power ES amps).  Both use the same tube, a quad of 6SL7's and a quad of EL34's but they couldn't be more different.  The WES is basically a quad of single ended amps asked to behave as a dual differential amp and doing it quite poorly.  Not low distortion by any means and the signal path is filled with capacitors.  The ESX on the other hand is just about state of the art for an all tube amp with some very clever twists (the cross coupled input stage is a nice touch) and there is just a single cap in the signal path.  The output stage is fully differential, with tremendous power and very low distortion.  From the outside these amps could look exactly the same...  

 

[kevin gilmore]

The BHSE runs at 800v.
There is more to tubes having the same pinout.
And this depends on whose datasheet you read, but...
 
An el34 is rated at 800 volts maximum plate.
And people push them to 1000 volts or more.
And they last a long time even when you abuse them.
 
A 6550 (kt88) is rated at 600 volts maximum plate.
And i know from experience that you can't push them
past 650 volts. I have tried.
 
A 6L6GC is rated at 500 volts maximum plate.
And most of them won't go past 450v.
 
All are otherwise functionally equivalent and the same
pinout. (if you tie G3 to cathode)

 

[daveDerek]

Quote:

 
The BHSE on the other hand could not be serviced by a tube tech from the 50's.  In fact most of it would make no sense to him as it really is an all solid state amp which simply uses tubes for the output as they are the best part for the job.  No single solid state part can replace the tubes and do as good a job.  Now the circuit is setup for the EL34's in mind and there are no large resistors here, all the operating points are set by transistors.  If the wrong or defective part were to be installed the first parts to go would probably be the cathode mosfets as they would overheat and explode.  That's not something which is easy to fix so best not do that...

 
can you comment further about how the tubes are utilized in this amp and why it's better than going solid state?
also, i have a recollection of dr gilmore stating that the way the tubes are used in this circuit minimizes the effects of toob rolling. why/how so is this? i still see folks commenting on seeking out pricey tube sets for this amp. is this an (expensive) exercise in futility and foolishness?
 
 
Quote:

 
You do bring up a good point though that people view amps with similar tubes as being similar when it couldn't be further from the truth.  Take two electrostatic amps, the WES and ESX (the fixed version of the Single power ES amps).  Both use the same tube, a quad of 6SL7's and a quad of EL34's but they couldn't be more different.  The WES is basically a quad of single ended amps asked to behave as a dual differential amp and doing it quite poorly.  Not low distortion by any means and the signal path is filled with capacitors.  The ESX on the other hand is just about state of the art for an all tube amp with some very clever twists (the cross coupled input stage is a nice touch) and there is just a single cap in the signal path.  The output stage is fully differential, with tremendous power and very low distortion.  From the outside these amps could look exactly the same...  

 
it sounds like you're highly touting the 'esx' amp.  is it similar at all to the bhse and how do they compare?
how different are the bh and bhse circuits?  and where do the kgss and kgss-hv stand in this whole ranking scheme in terms of sound, function, and reliability?
speaking of sound, function, and reliability doesn't that put all of the tube units at a disadvantage as they change over time and then go bad? how reliable and how long lasting are those above mentioned toob units?

 

[kevin gilmore]

There really is no solid state output device with the power and voltage range of an el34.
Say 20ma at 1000v.
 
The silicon carbide devices come very close, but to get them to behave you have to
run them at much higher current. About 50ma. A lot of heat. A LOT OF HEAT.
 
The BH,BHSE and T2 are the only amplifiers that drive the output tube grounded grid.
The most linear and lowest distortion method for doing this kind of thing.
 
The ESX is nothing like that. Output stage is common cathode.

 

[jcx]

grounded grid with high compliance lateral mosfet drain drive means virtually no "tube character" enters the equation in the BH - the tube output current is controlled by the fet driver current to within a few percent for audio frequencies
 
 
 
I see the smt version of these in distribution - still trying to get a quote on the T0-247
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[size=xx-small][size=xx-small][size=xx-small][/size][/size][/size]

 

[spritzer]

Quote:

it sounds like you're highly touting the 'esx' amp.  is it similar at all to the bhse and how do they compare?
how different are the bh and bhse circuits?  and where do the kgss and kgss-hv stand in this whole ranking scheme in terms of sound, function, and reliability?
speaking of sound, function, and reliability doesn't that put all of the tube units at a disadvantage as they change over time and then go bad? how reliable and how long lasting are those above mentioned toob units?

 
The ESX is basically a Stax amp designed in 1968 and given to the DIY community.  Single Power took this design and built it incorrectly so the ESX was designed as a fix for those amps.  It's about as good as it gets for an all tube electrostatic amp but the new Megatron circuit trumps it.  Not really comparable to the BHSE though as the ESX is a tradition tube amp with all the limitations they have.  There is a version which uses the same CCS as the BHSE but it's still a ways off. 
 
The BH and BHSE is the same amp but the BHSE uses different parts as the ones used in the original design had been discontinued.  It also incorporates some lessons learned with the older amps to make it more stable and to keep it cooler and thus last longer. 
 
KGSS and KGSSHV are very good but the BH still has the edge.  Some of this has to do with current limitations in the output stage due to the small heatsinks used so if they solid state amps were really pushed then it would be a closer race.  This is exactly what I plan to do with my next HV build. 
 
Tubes age but in the BHSE they will last years with normal usage and all amps will drift.  The electrolytic capacitors age and dry out and the heat cycles alter components after a while.  There is no way around this and SS amps can be just as bad in this regard.  The good thing is that tubes are cheap and easy to replace.  In terms of reliability it's hard to speculate but I've had Stax amps from the early 70's here with the stock tubes and the crazy heat monsters such as the SRA-12S are still running fine after 40 years once the capacitors have been replaced.  I KGSS from 2005 I recently modified measured like new so there should be no issues for the next 15 years or so. 

 

[ericohgb]

KGSS and KGSSHV are very good but the BH still has the edge.  Some of this has to do with current limitations in the output stage due to the small heatsinks used so if they solid state amps were really pushed then it would be a closer race.  This is exactly what I plan to do with my next HV build. 

Dear Spritzer,
Besides having HV mosfets as outputs, could you tell us the differences between those to amps?
Regards
Erico

 

[forbigger]

I swear I seen this answered in this thread but forgive me as I've used search and didnt turn up. and I dont have the virtue to wade through every single page of this thread. The 2 pro sockets on BHSE, can it drive 2 headphones simultaneously ? Eg. 009 and 007. Over a prolong period of normal listening session like 5-6 hours ? Thanks

 

[sridhar3]

Quote:

I swear I seen this answered in this thread but forgive me as I've used search and didnt turn up. and I dont have the virtue to wade through every single page of this thread. The 2 pro sockets on BHSE, can it drive 2 headphones simultaneously ? Eg. 009 and 007. Over a prolong period of normal listening session like 5-6 hours ? Thanks

 
Yes.  But the 007 and 009 have different sensitivities, so the volumes won't match.  One will be too loud and the other will be too quiet.

 

[Elysian]

We were driving a SR007A and SR009 simultaneously through my BHSE, and both sounded fine, though the SR009 was a bit louder.  We had the BHSE volume pot maxxed out, since we were using a preamp to manage volume.  The differences in volumes between the two were not drastic, and I was going between both headphones without any desire to change the volume.