Jump to content

KG Balanced Dynahi build discussion thread


Vortex
 Share

Recommended Posts

So, well, I was trying to compile a BoM of the original SuSy Dynahi 1.0 PCB from 2011 and there are a few discrepancies between the published BoM by Lil Knight and what I can see on the silkscreen, when it comes to the passive non-adjustable components. Which version is correct?

My rBoM (left) VS Lil Knight's (right):

image.png.4973401a009dbbc10ae01ca751c4983c.pngimage.png.e6ced931d6abeed584923c95edb25f0c.png

Apologies but I have a load more questions!

Where would be the resistors be that control the gain? I'm finding myself unable to find them...ideally I'd like a gain of roughly 10. What values of resistors and caps would this require? (Something like 11 or 9 would work fine).

Does the current/power rating of the red LEDs matter and do they have to be rated at 1.7V or would 2V work?

Would using 1000uF caps instead of 470uF work like I've seen some people in this thread do?

What would be the closest still available replacements be for the various transistors on the board?

Are the 7815s and 7915s necessary?

Think that's about it so far...thanks for bearing with me!

Link to comment
Share on other sites

So, well, I was trying to compile a BoM of the original SuSy Dynahi 1.0 PCB from 2011 and there are a few discrepancies between the published BoM by Lil Knight and what I can see on the silkscreen, when it comes to the passive non-adjustable components. Which version is correct?

My rBoM (left) VS Lil Knight's (right):

image.png.4973401a009dbbc10ae01ca751c4983c.pngimage.png.e6ced931d6abeed584923c95edb25f0c.png

Apologies but I have a load more questions!

I don’t have the schematic handy, but will try to answer what I can

Where would be the resistors be that control the gain? I'm finding myself unable to find them...ideally I'd like a gain of roughly 10. What values of resistors and caps would this require? (Something like 11 or 9 would work fine).

11 is the standard gain. Without the schematic, I can’t tell you which resistors though

Does the current/power rating of the red LEDs matter and do they have to be rated at 1.7V or would 2V work?

Use 1.7V unless you feel like calculating resistor values to arrive at the design CCS currents using something else

Would using 1000uF caps instead of 470uF work like I've seen some people in this thread do?

That should be fine. Use something that fits the board

What would be the closest still available replacements be for the various transistors on the board?

Are the 7815s and 7915s necessary?

Think that's about it so far...thanks for bearing with me!

Without the schematic, hard to say. If that shows the MPSWs you showed above, that could be a problem. Arrow may still have some. The nearest equivalent is the PZTA06/56, but those are surface mount. Also, I would assume that Kevin was using something more like MJE or MJF15030/15031 for the output devices?

The 7815/7815 are there so you don’t have to use OPA445 for the servo opamp. If you omit them, you’ll need an opamp that can handle your +/- rail voltage.

Also, I wasn’t sure if the lil knight boards were the Super Symmetry?

 

 

Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

3 hours ago, Pars said:

11 is the standard gain. Without the schematic, I can’t tell you which resistors though

Oh fair enough, that makes sense.

3 hours ago, Pars said:

Use 1.7V unless you feel like calculating resistor values to arrive at the design CCS currents using something else

Does it have to have the same current rating as the original chosen?

3 hours ago, Pars said:

That should be fine. Use something that fits the board

Ok, got it!

3 hours ago, Pars said:

Without the schematic, hard to say. If that shows the MPSWs you showed above, that could be a problem. Arrow may still have some. The nearest equivalent is the PZTA06/56, but those are surface mount. Also, I would assume that Kevin was using something more like MJE or MJF15030/15031 for the output devices?

There are a few different types that are required on the board. I'm aware that there were several different versions of transistors being used and my brain is confused as to which ones are the correct ones.

3 hours ago, Pars said:

The 7815/7815 are there so you don’t have to use OPA445 for the servo opamp. If you omit them, you’ll need an opamp that can handle your +/- rail voltage.

So if you do use an OPA445, you don't need the 7x15s? They seem to be available on mouser. https://www.mouser.co.uk/search/ProductDetail.aspx?R=0virtualkey0virtualkeyOPA445AP 

What kind of sound quality difference would there be between the two options, if you're aware of any?

3 hours ago, Pars said:

Also, I wasn’t sure if the lil knight boards were the Super Symmetry?

The ones I got are, and I'm fairly sure they were from the first Dynahi SuSy GB? Not too sure though. Anyways, this is the silkscreen for them. d2.thumb.jpg.17b79cb6fb96ae783f3fbfce7c9d27f8.jpg

3 hours ago, Pars said:

Sent from my iPhone using Tapatalk

I am...incredibly impressed that you managed to type that much on mobile.

Anyways, thank you for the help! <3

One more question. Would a 10k pot work for the input? I read some stuff about the input impedance of this amp being low and stuff but I didn't fully understand it...

Link to comment
Share on other sites

On 10/21/2012 at 2:32 PM, sbelyo said:

I'll be using a 10K balanced volume control. Balanced gain will be 10 by changing R52, R56 to 50K and C1, C3 to 5 pf.

See this post by me.  That info came via PM from KG

I have those boards and will populate them in the next month or so

Edited by sbelyo
Link to comment
Share on other sites

I count 7 5K resistors...

2 minutes ago, Pars said:

Agree with sbeylo.
The gain resistors in your silk above are the 200k/10k and cap next to them.
Some of the sand shown could be problematic:
2sa1145/2sc2705
2sa1358/2sc3421
2sa1349/2sc3381




Sent from my iPhone using Tapatalk

I have them all, did you mean problematic to find?

Link to comment
Share on other sites

Ok phew I'm not imagining things then cause I'm pretty sure a couple of the boms I saw had 8 of them.

I...have none of them. Even the K170/LSK389 confuses me. If I want the LSK389 do I get the A or C grade? Etc.

I think I started off with something quite advanced here but I must persevere!

Link to comment
Share on other sites

What's the range of the servo?  I'm looking to build the new BIII pro and the new output stage uses servos to control the offset.  When measured the balanced output is showing 0.5 mv, the se output is showing around 1mv.  I know the gain will happily multiply that so that plus adding in what may show up from just building the amp I'm wondering if it's too much for the servo to handle

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...