KG Balanced Dynahi build discussion thread

[sbelyo]

Sure, I'll do it today. I may add these boards to my group buy


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[sbelyo]

Here's the board...  

I have all the parts to build it.  Should I go ahead or is there a later version for the parts used?

[UFN]

That's probably from the first GB (check the beginning of the thread). It should be fine to build if you have the parts, but they are all obsolete now, so if you are missing something it might be hard to get hold of. IIRC the newer boards were mostly made because the old parts weren't available any more, not because the newer parts are better.

//UFN

EDIT: Hang on, you are writing "the board" as in one? - remember one board = one channel.

Edited October 2, 2016 by UFN

[sbelyo]

i did notice that my boards have warped a bit.  Not a terrible amount but its there.  Any problem with that?

[johnwmclean]

Should be fine. Several of these earlier boards were warped for some reason, even with the HV stuff I’ve not had any issues.

[sbelyo]

I've added the latest board with offboard heatsinks to my group buy

https://docs.google.com/spreadsheets/d/1Z1L3MQuuY4ZTUyPQb1qBmVJp8MtC7qEzBUui3z5dFrQ/edit#gid=0

If we can get 5 sets I'll place the order

This is the board

http://gilmore.chem.northwestern.edu/boards/ssdynahibalsmtm.zip

Edited October 2, 2016 by sbelyo

[ti5002000]

Hi guys

Sorry for this noob question but i just want to check if this is ok.

Looking at the picture is this the right way to measure Dc offset?

In the input i have the wires that come from the potentiometer.In the output i have the multimeter connected to positive and negative output.

Once again sorry but i don´t want to damage something

Thanks

 

Edited December 24, 2016 by ti5002000
remove image

[Pars]

This is a balanced Dynahi? That is one measurement (offset of O+ to O-). First, you should set DC offset for O+ to gnd and O- to gnd. Get these both as close as possible; should be able to get each to within 5mV without the servo. If you can't, get them as close as possible. Then check O+ to O-. Not sure what these boards have for pots on them. By going back and forth, you should be able to get them all pretty close.

EDIT: and have the inputs either grounded or turn the volume pot all the way down.

Edited November 5, 2016 by Pars

[ti5002000]

7 minutes ago, Pars said:

This is a balanced Dynahi? That is one measurement (offset of O+ to O-). First, you should set DC offset for O+ to gnd and O- to gnd. Get these both as close as possible; should be able to get each to within 5mV without the servo. If you can't, get them as close as possible. Then check O+ to O-. Not sure what these boards have for pots on them. By going back and forth, you should be able to get them all pretty close.

Yes this is a balanced Dynahi.By Ground (i mean the ground where i should put the black probe) you mean the output pad ground ,correct?

And volume all way down .

Thanks Pars

Edited November 5, 2016 by ti5002000
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[Pars]

Yes, board ground, should be the same anywhere on the board, probably the middle terminal on the 3-pin connectors.

[ti5002000]

Yes,maybe the picture isn´t in a good angle....the boards i have is the dynahibal9 version from Kevin.

I was in doubt after the biasing ,if for measure dc offset the ground i should use is the input pad ground...But it has to be output pad ground as you said ,because measuring with the input pad ground give me strange results.With the output ground it is ok .Already gives only 30mv to begin with..

Thanks for your great help

Tiago

[Pars]

Actually the input ground and output ground are the same (single ground plane). Same for the power ground.

[ti5002000]

1 hour ago, Pars said:

Actually the input ground and output ground are the same (single ground plane). Same for the power ground.

Very well.Appreciate the useful info.

Regards

Tiago

[samhuang]

Just got my susy dynahi + σ22(gain is 8x), working really well with high impedance headphone in balanced setup(like T1).

But paring with my denon a100(a low impedance and high sensitivity headphone) with it, I kept hearing hiss.

Is there anyone pairing dynahi with low impedance and high sensitivity headphone? 

Because I plan to pair elear with dynahi, just worried about the hiss will ruin my whole setup.

 

[ang728]

Kinda rebuild&upgrade

mainly switched voltage regulators from Sigma 22 to GRLV,

Owner siad he can totally feel the improvment.

 

 

[Pars]

On 3/16/2013 at 7:40 AM, StrawHat said:

I tested all the transistors before stuffing the boards but I did it with one of those DMM hfe testers I think my testing is not very reliable.

I have already ordered a new set of boards from Lil'Knight so I will definitely continue this project but before continuing I need to buy a good DMM and one of those transistor testers.

I was thinking of buying this one:

 

http://www.peakelec.co.uk/acatalog/dca75-dca-pro.html

 

Anybody has any experience with it? Seems a little better than the DY294.

 

On 3/16/2013 at 10:24 AM, kevin gilmore said:

looks like a nice tester.  But it can't test the high voltage stuff.

I will buy one anyway.

Kevin,

DId you ever buy one of these? If so, what do you think of it?

[sbelyo]

I'm getting ready to order some power transformers.  For one SuSy Dynahi board powered by one GRLV, is 80 VA sufficient, or is 100VA better?

[GeorgeP]

On ‎15‎/‎11‎/‎2016 at 8:23 PM, Pars said:

 

Kevin,

DId you ever buy one of these? If so, what do you think of it?

I bought one. Seems to work well. Curve tracing feature is pretty nice too. Don't know how it stacks up against more established testing devices though. If you have any questions about it, I can try to answer them.

[kevin gilmore]

The thing from lockty7, yes I bought one, and had Marc write some custom scripts

works very well up to 40 volts or something like that

[luvdunhill]

What do you need matched Chris? I need some zen moments in front of the matcher.

[Pars]

Nothing at the moment Marc. Maybe some JFETs in the near future.

Speaking of which, has anyone heard of a vendor called Heisener? They claim they can get genuine 2SJ74-BLs for $3@, and say they will guarantee them. I looked and I have 60+ SK170s, but no SJ74s

dumb

[luvdunhill]

I guarantee my own devices just let me know, I am off next week.

[luvdunhill]

On 11/17/2016 at 4:24 PM, kevin gilmore said:

The thing from lockty7, yes I bought one, and had Marc write some custom scripts

works very well up to 40 volts or something like that

Here's the spread I got on 100 devices. Granted this batch has been picked over a bit, but usually the p- devices show way more variation. 

[Pars]

On 11/17/2016 at 4:24 PM, kevin gilmore said:

The thing from lockty7, yes I bought one, and had Marc write some custom scripts

works very well up to 40 volts or something like that

No, I was referring to the Peak Atlas DCA75. I had run across the Lockty7 thing on diyaudio and it looked interesting as well.

I'm just looking for the best inexpensive device tester for validating devices. DY294? The Atlas DCA (though it is 4x the price of the 294, and won't do higher voltages).

[luvdunhill]

I think you will need to measure a few different things, not just Idss. However, my experience is the curve is immediately telling. So perhaps take three measurements (-.2V, 0V, .2V) and compare to the variance I posted above. My curves show Idss of 6.25mA to 11mA which is about what you would expect for BL grade.