[David1961]

Quote:

Is the one you heard today the Mk I or Mk II?

 
Ian said they're the mk1's

 

[IanG]

Quote:

 
Ian said they're the mk1's

Yes they are mk 1s.
 
David and I hadn't listened together to these headphones on David's gear since our first and only try two months ago. (Nor have I listened to both on my gear). At that time we felt there were discernible differences with little if anything favouring the 007s.
 
Yet yesterday both headphones sounded great; perhaps the 009s had a touch more detail and there was certainly a frequency difference with the 009s sounding brigher and the 007s sounding darker. Because there are much bigger deifferences on individual recordings some sounded better on the 007s and some sounded better on the 009s. Indeed some listeners might find the 007 to be a preferred  unit for really long listening sessions because they are never bright - although not physically as comfortable as the 009s.
 
The difference is unlikely be down (in my opinion) to human factors (getting used to the sound) because we have not heard the 007s or run the comparison regularly - this is just the second try.
 
It may be down to
- the BHSE being bedded in (it must be 3 months old now); or
- the BHSE being thorougly warmed up compared with last time; or
-  the fact that we had just biassed the values as accurately as we could (neither of us know whether rebiassing the valves (and they were way out) has a sound quality impact or just a valve-lifetime impact).
 
Both are great headphones run by a great amp.

 

[David1961]

Comfort wise I find the 009's better than the 007's, I could also listen to the 009's for hours and hours driven by the BHSE, but I could only do that if the volume was at hand which mine is. Whereas with the 007's, adjusting the volume wouldn't be a necessity, all instruments sounded just right even when listening at above my normal volume. I'm happy that I got the 009's but I'm now sorry I let my 007mk1's go, whoever got those knew they were getting very well looked after headphones because they were like new, even though I'd had them for over 10 years. 
 
The valves used last night were the SVETLANA EL34's recommended to me by Birgir which I'd like to thank him for. All I did was just follow the video Justin did so I'd also like to thank him for doing it.

 

[TheAttorney]

The 007 mk1's comfort can be improved,some say, by getting the mk2 pads. For 2 reasons: the mk2 pads are slightly thicker, so less likely that anyone's big ears will rub against  frame. Also the real leather has less sweat issues than the artificial leather of the mk1's. So I'll definitely be replacing my mk1 pads (after the UK meet).
 
I've now listened for a few hours to my own recently delivered BHSE (with 007 mk1), and I'm aiming to post my impressions within the next day or so.

 

[spritzer]

A far more likely cause for the change would be the SR-007 being properly charged.  Normally this isn't an issue but changes in environment, lack of use etc. all tie into this.  While the bias current rushes into the diaphragm in an instant it can't overcome all the resistance instantly so it takes a while to charge up if they have been left sitting. 
 
As for comfort, I will never go back to the brown Mk1 pads and all my sets have the Mk2 earpads.  More comfortable and it sounds better.  It is also crucial to bend the arcs to get the most out of them and it also improves the comfort. 

 

[David1961]

Quote:

I've now listened for a few hours to my own recently delivered BHSE (with 007 mk1), and I'm aiming to post my impressions within the next day or so.

 
Hi Richard,
 
When I fist heard Ian's 007mk1's which was about two months ago I also listened to my 009's the same time and I preferred my 009's. At that time I'd only had the BHSE for about 3 - 4 weeks, but also the power hadn't been on the BHSE for long before we started using both headphones. Last night we listened to both amps with my BHSE but this time it had been on for about 4 hours and his 007's sounded miles better than before. 
 
 
                              Dave.

 

[IanG]

Quote:

A far more likely cause for the change would be the SR-007 being properly charged.  Normally this isn't an issue but changes in environment, lack of use etc. all tie into this.  While the bias current rushes into the diaphragm in an instant it can't overcome all the resistance instantly so it takes a while to charge up if they have been left sitting. 
 
As for comfort, I will never go back to the brown Mk1 pads and all my sets have the Mk2 earpads.  More comfortable and it sounds better.  It is also crucial to bend the arcs to get the most out of them and it also improves the comfort. 

On both occasions the 007s had not been used for a while - perhaps two weeks.
 
On the question of temperature/humidity: pass. Similar days as far as I can recall, the first in summer, the second in early autumn.
 
Listening duration: pretty similar.

 

[vvs_75]

Quote:

 Also the real leather has less sweat issues than the artificial leather of the mk1's. So I'll definitely be replacing my mk1 pads (after the UK meet).
 

  
     First time hear that mk1 has artificial leather pads. Back then the SR-007 Mk1 was  Stax top most expansive model why would they use artificial leather? . 
Also I always thought that the air port on Mk2 pad is the reason for sound change in the SR-007Mk2.

 

[vinyllp33]

Hi Richard,

When I fist heard Ian's 007mk1's which was about two months ago I also listened to my 009's the same time and I preferred my 009's. At that time I'd only had the BHSE for about 3 - 4 weeks, but also the power hadn't been on the BHSE for long before we started using both headphones. Last night we listened to both amps with my BHSE but this time it had been on for about 4 hours and his 007's sounded miles better than before. 


                              Dave.

I find the BHSE needs at least an hour or so before it starts really opening up. Once I get past the 4-5 hour mark I have not noticed any significant changes. However, I must admit after it has been cooking all day and I give it a listen, the resulting sound is so engaging that I must literally force myself to shut it off lest be up until well after dawn.

This is really not surprising in that at is core the BHSE is essentially a Pure-Class A, solid state design and in the ideal world those amps should never be turned off for best sonic performance.

But of course since they draw full power at idle, this is often impractical due to energy consumption and heat. This is the precise reason Krell changed to their "Sustained Plateau Bias" (sliding-bias) design. I remember my KSA-250 (pre SPB) used to pull 12 amps continuously from the wall!

 

[googleli]

If the sonic difference is huge, I wouldn't mind paying a bit more for electricity or endure the heat, or even let the tubes suffer from a much reduced tube life by turning the amp on 24X7. But the main problem with tube amps is that in case of a tube failure, the amp may be damaged and in the worst case cause a fire, if left unattended. If Justin could chime in on the safety aspects of leaving the BHSE on all the time, that would be much appreciated.

 

[vinyllp33]

No, I would not recommend leaving a tube amp on unattended for the exact reasons that you describe.

In theory it would probably be fine; I leave my McIntosh tube preamp on when I am out as small signal tubes like 12ax7 operate at much lower voltages but never a tube power amp.

I don't think the difference huge, just give it around an hour's warm-up and you are probably around 90% there. I usually fire mine up when I get home and once I get settled in and ready to listen the BHSE is ready to sing.

 

[wuwhere]

I've left my speaker tube amp on overnight at times. But one time I heard a crackling sound coming out from my HE-6 and one of the 6550 vacuum tube was getting destroyed inside the glass tube.

 

[jhellow]

I made my first tube change since I received the BHSE from Justin 18 months ago. I am running the unit with GE Big Bottles, 6CA7s. A very nice matched quad, that was a little low in output but very quite and I thought very transparent, while a bit light in the bottom end. But I was very satisfied.

I am using my BHSE with the 007 Mk1s and a Wadia 781i as a source component. The BHSE sits on a BD Racing Shelf for the Source that floats on a Sony Esprit magnetic suspension.

JHellow

 

[TheAttorney]

Quote:

 
     First time hear that mk1 has artificial leather pads. Back then the SR-007 Mk1 was  Stax top most expansive model why would they use artificial leather? . 
Also I always thought that the air port on Mk2 pad is the reason for sound change in the SR-007Mk2.

Don't feel bad about the Mk1 pads. They're very soft and supple, yet have lasted me years. Just that the Mk2 pads are allegedly better. The 007 Mk2 does have an air port, which some say spoilt the sound a bit, but the port is in the main structure, not the pads, which are still designed to give a complete seal. Spritzer could probably give the definitive explanation here.
 
Quote:

But the main problem with tube amps is that in case of a tube failure, the amp may be damaged and in the worst case cause a fire, if left unattended. If Justin could chime in on the safety aspects of leaving the BHSE on all the time, that would be much appreciated.

I'd also like to know about this. The BHSE power supply has 2 fuses at the back, presumably one per output channel to protect the amp. But I couldn't find any inbound mains fuse - if that's so, then that's the first time I've come across an amp without a mains fuse. So it would be good to know why that is and how the BHSE is protected against the most likely failures.
.

 

[David1961]

The longest I've had my BHSE on for is about 9 hours and it ran like a dream, but I was in my home in all that time. It would probably be safe to leave the BHSE on for days but I'll never do that because I'll never have it or any of my audio equipment on unattended.
 
P.S. Since getting my BHSE my electric bill has gone down and by some, I have had solar panels installed though.