Roll Call: Who's building, built, or thinking of building a beta22?

[Zashoomin]

So I just finished my new beta and I thought I would show it off here.  It is fully balanced with 4 channels, has epsilon 24 muting circuit.  
 

The amp has no back panel because front panel express over milled one of my panels and I had to wait for them to send me a new one. 
 

Power supply
 

Off
 

Back with everything plugged in chaotically.
 
It sounds great, and is dead silent.  Just burning it in now and making sure everything is working as intended.  

 

[funch]

Very nice. Who did the front panel? I really like the script engraving, and the led's around the volume knob is a nice touch.

 

[Zashoomin]

  Very nice. Who did the front panel? I really like the script engraving, and the led's around the volume knob is a nice touch.

Front Panel Express did all 4 of my panels.  That script is in their software that they offer for you to use.  The so called LED's are actually just holes that I had them drill half way through the panel 

.  With the right light it shines a bit.  

 

[funch]

Ah, I see. It must have been the flash that made them look illuminated. On one of my FPE panels that was too thick for the LED to reach through,
I had a countersunk hole done on the outside of the panel. Worked pretty well.

 

[fishski13]

excellent job Zash!  

 

[Zashoomin]

  excellent job Zash!  

Thanks 

.  Now time to build a Dynahi and Krell KSA 5

 

[fishski13]

the KSA-5 should be a breeze after building a balanced B22.

 

[Zashoomin]

  the KSA-5 should be a breeze after building a balanced B22.

I sure hope so.  I ran into so many problems that delayed this amp, not all of them being mine.  I am excited to see which sounds better.  

 

[Zashoomin]

A couple more pictures...I have no shame.  I replaced the cheep chinese pot with a goldpoint one.  Looks better and also all the turns feel better.  

 

 

[Teerawit]

Awesome. Did you tap the V+ and V- power rails for the epsilon 12 from the DC input directly or from the amp boards?

 

[Zashoomin]

  Awesome. Did you tap the V+ and V- power rails for the epsilon 12 from the DC input directly or from the amp boards?

Directly from the power rails.  I think that it makes wiring easier that way.  

 

[SilverEars]

I'm curious what the Beta will do to a K701. I know it's bass light, and it's not as easy to drive as typical dynamics.  I wonder if it will drastically change the sound from a typical amp.  Anybody try it on Beta 22?  
 
Anyway, the HE-6 sounds fantastic on the 2 channel Beta 22.  It's hard to believe it could get better with 4 channels.

 

[fishski13]

I like like the K701 pairing provided you increase the quiescent current to 180mA and add 100R or so output impedance.

Provided you have a gain of at least 8x to achieve the 15Vrms/43Vpp that the B22 is capable of with a source that puts out 2Vrms, an unbalanced B22 has plenty of V to drive the HE6. Balancing will double the Vswing and give you more Class A/B current delivery, but total Class A current delivery will not increase.

 

[SilverEars]

I like like the K701 pairing provided you increase the quiescent current to 180mA and add 100R or so output impedance.

Provided you have a gain of at least 8x to achieve the 15Vrms/43Vpp that the B22 is capable of with a source that puts out 2Vrms, an unbalanced B22 has plenty of V to drive the HE6. Balancing will double the Vswing and give you more Class A/B current delivery, but total Class A current delivery will not increase.

I guess the output impedance will alter the FR, probably cut off some of that spark the K901 is known to have and boost the low end?
 
Anyway, I have an interesting question.  Have you guys experienced warm-up period with headphones or your Betas?  I noticed that my HE-6 initially doesn't sound that great until I have it playing for awhile.  Could it be my Beta or HE-6 taking time to warm up?

 

[fishski13]

no proof, but i personally believe that the AKGs were tuned with 100-120ohm output impedance.  adds some needed warmth.
 
MOSFETs havve a negative tempco and will run at a higher bias initially when cold before dropping after thermal stabilization.  i'm guessing you could be hearing the sonic impact of a different bias?  for me, i prefer the sonics of a slightly higher bias at 180mA, measured immediately after taking the chassis lid off.