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Lehmann Audio Black Cube Linear headphones amp. *** Pictures *** - Page 3

post #31 of 52
Thread Starter 

It's been awhile since I posted on this thread.  I still own both BCL and still feel that it is the BEST most neutral amp I've auditioned.  The thing about the BCL is it's power and control.  It's more apparent listening on Sony MDR-XB1000 (70mm drivers).  That headphones pound with deep bass and control on the BCL.  All other amps I've tried could not produce the same listening experience.  The BCL is not for everyone.  It doesn't add any flavor to the music.  Garbage in garbage out.  Someone here mentioned the Burson.  I had the Burson for two week (Thank you Burson Audio) to play with.  It sounded great in the beginning, but got boring after a few days of use.  That amp's sound didn't excite me.  

 

Can someone link the info about an upcoming amp from Lehmann?  I would love to learn about what's next for them.

post #32 of 52

x2 beerchug.gif

post #33 of 52

Exactly. Negative feedback has good and bad points. Usually if transistor section is balanced well then there isn't too much benefit of feedback. If feedback were involved in BCL amp, it wouldn't be so easy to change opamps without tuning the rest of the circuit. I noticed that even without feedback and messing with topology, ultra fast opamps like AD and LM are prone to oscillation. Slower TI (Burr Brown) work without problems. You can change them like t-shirts.
But who has time and wants to do something on his own I would suggest trying to use the same signal topology from Black Cube Linear but instead of one rectifier with two LM-s use separate power supply (each channel has its own regulators and transformer and separate supply for opamp). You wouldn't believe how much is supply involved in entire picture. Also, transformer is very important. The bigger - the better (well, over 100VA benefit is almost none, so one 60VA  (or 2x30) or one 80VA (or 2x40) is the best choice). Separate power supply makes more power (deeper and faster bass) and channels are separated more.

 

Now I think about two OPA 604 instead one 2604. Hm...

 

I haven't seen that Jaycar kit amp but when we talk about noises ground topology (grounding) is the most important. If you have good grounding circuit and fully separated power circuit from signal circuit - noise will be none ("non audible"). It does not matter if you use EI transformer with 300 VA pure power, toroidal with four separated rails or something else. 
 

 

 

Quote:
Originally Posted by SP Wild View Post

What shocked me also was learning about circuit topology and schematics after building the Aussie Jaycar kit amp, and to find that the output topology of this 30 dollar amp was the same using the same output transistors and opamp input topology.  The only difference being the Lehmann was without negative feedback and the Jaycar had feedback.

 

However with all my cans, the kit amp had better channel separation - possibly due to a more symmetrical circuit layout.  With the LCD2s, I could hear that the Lehmann was faster and the kit amp was a little smeared in transient - this wasn't noticeable with the quick HD800s.  Possibly because NFB will affect timing.  Still - a 30 dollar kit amp that had no disadvantages driving the HD800 and with better channel separation...and quieter too possibly because of the PSU board was a separate piece.  Does bring the question of pricing.



 

post #34 of 52

Burson has slightly better supply (driven by Hitachi transistors 2SA1930 and 2SC1571 - there isn't LM regulators at all). But supply is not fully separated. Also Burson has better opamp-s. Output topolgy is almost the same as it is in BCL. Instead of BD-s, Burson uses Hitachi 2SA and 2SC (I think 2SA1930 and 2SC5171 which are faster than BD-s).
 

Quote:
Originally Posted by DjAmTraX View Post

It's been awhile since I posted on this thread.  I still own both BCL and still feel that it is the BEST most neutral amp I've auditioned.  The thing about the BCL is it's power and control.  It's more apparent listening on Sony MDR-XB1000 (70mm drivers).  That headphones pound with deep bass and control on the BCL.  All other amps I've tried could not produce the same listening experience.  The BCL is not for everyone.  It doesn't add any flavor to the music.  Garbage in garbage out.  Someone here mentioned the Burson.  I had the Burson for two week (Thank you Burson Audio) to play with.  It sounded great in the beginning, but got boring after a few days of use.  That amp's sound didn't excite me.  

 

Can someone link the info about an upcoming amp from Lehmann?  I would love to learn about what's next for them.



 

post #35 of 52
Quote:
Originally Posted by BlaBlaBla View Post

Burson has slightly better supply (driven by Hitachi transistors 2SA1930 and 2SC1571 - there isn't LM regulators at all). But supply is not fully separated. Also Burson has better opamp-s. Output topolgy is almost the same as it is in BCL. Instead of BD-s, Burson uses Hitachi 2SA and 2SC (I think 2SA1930 and 2SC5171 which are faster than BD-s).
 



 


The bcl sounded BETTER to my ears...I am clueless how lehmann does it.
I guess it's a black art from a certain point onwards.
I am no techqie:p

( I honestly did try to like the Burson....I had it for a few months. it's a beefy sounding amp)
post #36 of 52

hello i have hd800 + dac1 usb and headroom micro amp. The lovely cube is better than micro amp? Why? thanks

post #37 of 52
Thread Starter 
Quote:
Originally Posted by Lorspeaker View Post


The bcl sounded BETTER to my ears...I am clueless how lehmann does it.
I guess it's a black art from a certain point onwards.
I am no techqie:p
( I honestly did try to like the Burson....I had it for a few months. it's a beefy sounding amp)


+1 on both.

 

 

post #38 of 52
Quote:

Originally Posted by BlaBlaBla View Post
 

<snip>

Also, transformer is very important. The bigger - the better (well, over 100VA benefit is almost none, so one 60VA  (or 2x30) or one 80VA (or 2x40) is the best choice).

 

If one was to replace the torroid inside the BCL with a 80VA torroid what other power supply components would need to beefed up to handle to current rush upon power-up?

post #39 of 52
Quote:
Originally Posted by Tribbs View Post

 

If one was to replace the torroid inside the BCL with a 80VA torroid what other power supply components would need to beefed up to handle to current rush upon power-up?

 

If you want to replace toroidal transformer with bigger (80VA) you should change 230V fuse to 0.63 A or 1 A. Cold start (inrush current) will be higher because bigger toroidal transformer (higher magnetization current when powering up the amplifier) and everything else (after transformer) can be the same. If you have 110V power grid then current is doubled so in that way must be the fuse (2A). For fast fuses inrush current is real pain (it can be over 5 A in a very short time).

If you use slow blow fuses you can go with less (0.3 A or 0.5 A) because they will not react (melt down) for such short period. After magnetization and when main capacitors are filled up, current is very low (I think less than 0.1 A).

 

post #40 of 52

Actually, this question is for my Lovely Cube here http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/960

 

Ok, so the power supply diodes and caps can handle the surge current from 115Vac mains - Change the fuse to Slo-Blo.

post #41 of 52

Hi

 

Any suggestions please as to what might be a good stand alone DAC to pair with the BCL to avoid getting the BCL USB DAC, for about the same cost difference as the latter usb model? In the uK this would mean £300 for the DAC.

I hear this is a possibly a better way to go for sound quality and value for money.


Cheers

 

post #42 of 52
Quote:
Originally Posted by trotoir View Post

Hi

 

Any suggestions please as to what might be a good stand alone DAC to pair with the BCL to avoid getting the BCL USB DAC, for about the same cost difference as the latter usb model? In the uK this would mean £300 for the DAC.

I hear this is a possibly a better way to go for sound quality and value for money.


Cheers

 


Try Cambridge DAC Magic or Audiotrack Dr DAC.

 

post #43 of 52
Quote:
Originally Posted by Tribbs View Post

Actually, this question is for my Lovely Cube here http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/960

 

Ok, so the power supply diodes and caps can handle the surge current from 115Vac mains - Change the fuse to Slo-Blo.



Supply caps won't blow unless there is overvoltage or wrong polarity. Even in that case it will take a minute or two. You can put them AFTER transformer that has 1kVA power and they will be ok.

 

Diodes will blow when current through them is greater than specified. That means that you can't place load AFTER diodes that will need current greater than than diodes. But also you can place 1kVA transformer before diodes and they will be ok.

 

Load is on the first place and load makes rules. In your case for capacitors, load are headphones, LED diodes and transistor circuit. For diodes load are capacitors, headphones, LED diodes and transistor circuit. For transformer load are diodes, capacitors, headphones, LED diodes and transistor circuit...

post #44 of 52

Thanks for your advice Blablabla.

 

I notice there is a cambridge dac magic plus with a built in a headphone amp and bluetooth. Which is just within my price range. The intention is still as accompany the Lehmann but it may add extra versatility for around the home.

 

Thanks again!

post #45 of 52

Therefore, for all practical purposes, the initial power-up surge that occurs is:

 

1. to magnetize the 80VA torroid (Slo-Blo fuse).

2. Current through Vishnay BYV27-200  Diodes (specs)

3. to initially charge up the (35V/4700uf) PS caps.

 

Current through #2 and #3 is same regardless of PS transformer VA specs.

 

Alright, I think I've got it.

 

Thank you BlaBlaBla,

 

YadaYadaYada


Edited by Tribbs - 1/22/12 at 2:44pm
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