krell ksa5 klone

[Wolverine]

The HD800 headphone is excellent, but the combination with beta 22 it is not ideal.

[Voltron]

HD800 and B22 do not sound good to me either.  HD800 on a Luxman P1 is a beautiful combination to my ears.  But DT880 is anything but balanced or true to my ears, regardless of amp.  Musical is not really a descriptor of a headphone that makes much sense to me.  DT880 is not as accurate and will be more forgiving than an HD800, but that doesn't mean it is better or "musical" in comparison.

[morphsci]

The DT-880-600 is bitchin' dude.

[luvdunhill]

Its not understood the need to respond in such a way, you have not heard this combination ...

I have.

Also, queue Shelly that I don't listen to music, I like to watch waveforms.

I am actually providing a useful datapoint for you. If you like "musical" you will probably dislike anything I like, as tastes seem to obey transitivity laws. I would not recommend you try Stax, for example.

Stating the negative can often be a positive thing.

Edited June 9, 2014 by luvdunhill

[Remolon]

C8, C9 polarity

If I understand correctly the PCB, the servo circuit capacitors C8 and C9 are connected this way: -//+ +//-.

My question is what is the resulting capacitance and the polarity of C8 + C9? Or there is no equivalence for the set?

[kevin gilmore]

same capacitance as 1 of them. Just bipolar. There were bipolar blackgates available, so

you would need only 1

[Remolon]

Thanks Kevin.

 

So, choosing this solution and not only one bi-polarized capacitor is mostly for aesthetic reason?

[spritzer]

Two caps wired back to back in an non-polar cap.  Non polars aren't all that common with the Nichicon ES being one of the few good ones left. 

[kevin gilmore]

my clone is an EXACT clone. every part in the same physical location as the original.

Same exact board size etc. If I wanted to change it, it would not be an exact clone

[muskyhuntr]

Been matching the small transistors for my build using the Peak DCA Pro.   On the first batch of 25 MPSA06g's, my hfe's ranged from 176 to 217 with values equally distributed through the spread.  Thinking I could tighten this up, I ordered a second set of 25.  This time the hfe's ranged from 247 to 299.  Again, with values equally distributed.  That is a big difference between two batches!  Is this normal for different batches?  Of the 2 different batches, which one has the more typical Hfe readings.

 

Additional information:  Both batches came from Mouser.  Transistors in first batch were marked MPSA06 E07, the second batch were marked MPSA06 C25.  I believe the E07 and the C25 represent date codes.  The data sheet only shows the hfe's as having a minimum of 100.  I randomly checked both batches a few days latter and readings remained the same.

 

I also tested 50 MPSA56s.  They ranged from 193 to 215.  As it stands, I'll be pairing these with first batch of MPSA06s.

 

I would appriciate any insights on this.

 

Me

[luvdunhill]

Measure one device and wait 20 hours and remeasure it...

[mmoraw]

For those interested, I have one amp board and 2 power supply boards I would like to get rid of.

 

Me

Just wonder if still up for sale.

Thanks

[muskyhuntr]

I finally finished populating my amp board.  Went a bit nuts on component matching, resistors to less than .1% and transistors to less than 3%.  I wired up the boards and ran some square, sine, and triangle waves through it.  Every thing appeared perfect on the scope.  Bias was easy to dial in.  It was time for some listening.  I spent about equal time listening with my HD 600's and DT880's (600 ohm) and I have to say they both sounded great.   Everything from Gerswin to Joplin to Kodo...this amp does every thing right!   Next step is casing.

 

Me

 

 

[Victor Chew]

Congratulations.

[GrindingThud]

Very nice! I'm curious, after matching, what was your DC offset without the servo in?

[muskyhuntr]

Without the servos I get 67.5mv on the left and 76.5mv on the right.

 

Me

[GrindingThud]

Cool, mine was just over 110mv unmatched.

[fishski13]

congrats. enjoy. 

[Amar]

Hello,

 

I got word of this great project thru a friend who mentioned Kevin's remark about it being "HE6 killer" with the 35V rail configuration, So i'd like to attempt it to make my K1000 sing with a zest I never quite heard of them yet... 

 

Unfortunatley i only learned about the alternative, beefier (?) PSU after i had aquired the boards with the orginal PSU. Is it still doable to push to 35v rails with it? I read that entire thread but there's no specific reference about the matter other than Kevin states that the newer PSU can support a balanced configuration.

 

I'm also not clear wrt to the modification requirements besides the changing of the servo opamp. Moving to 50V electrolytes goes without saying i suppose. anything else? Sorry i'm not very technical minded, please bear with me. 

 

 

[kevin gilmore]

you change R7/R10 to 350 ohms  which will give about +/-33V on the power supply.

[Amar]

Hi Kevin, If i'm not mistake your instruction relates to the new psu, which i do not have. In the original dual-zener psu that i have will changing R1/R3 have the same effect? Or do i need the replace the zeners instead? 

[kevin gilmore]

you have to replace all 4 zeners. the second stage zeners need to be 33V and

the first stage need 40V

and the caps need to be voltage upgraded

[Amar]

I understand. and to wrap it up, what adjusted trafo voltage and current output would you suggest?

 

Anything in particular from Hammond's 1182 series that's the only availablity from Mouser for this matter:

http://il.mouser.com/Power/Transformers/Power-Transformers/_/N-8u9n5?P=1z0j7ozZ1yz4cc8Z1yz4cc7Z1z0wd2bZ1z0wd3aZ1z0j5qxZ1yvyg7o

http://www.hammondmfg.com/1182.htm

[kevin gilmore]

something with a pair of 35V windings would be ideal, 40V windings are going to probably overheat the

power supply. And you may have to adjust the bias generator to lower the standing current.

[Amar]

Thanks Kevin, I'll try my best to put that info to good use.