Hi all

UPDATE: never mind, I found em! Internet Archive to the rescue!

I'm thinking of rolling my own PCB for this. Does anyone have the schematic for the non-Mini version? I don't need the power supply, just the amplifier section. I've been through the whole thread and the links all seem to be dead. The images I did find are too blurry to make out. 

Thanks a ton!

Hi All,

I am looking at building a dynalo SMT/SMD system, balanced in / balanced out. I have been through this thread back to front as well as the staxmafia thread etc. I think I have got the most recent gerber files (dynalobal17) as well as the schematic (kgdynalobalssproduction.PDF) and I have started building a BOM but have stumbled on a few things that I was hoping some may be able to assist with?

1. Looking at a few comments, all resistors are 0805 size but I am not really sure of current size etc (have shot for 200mw .1% 25ppm at the moment).
2. The schematic does not line up with the pcb with regards to the caps - the schematics only shows 3 (from memory) whereas the pcb shows as many as 12 documented with values - is there an updated schematic? Or am I using an outdated gerber?
3. There appear to be a couple of caps on the PCB that have no values - any hints? (see attached pics) Or are these for something else?
4. Is there a bom available anywhere? I see reference to a xls in a few placed but cannot find the file - am scratching my head on what caps, trim pots, part size for SMD transistors etc
5. Is this project no longer active / am I barking up the wrong tree? It looks like a great project, but maybe there is a newer project I should be looking at?

Cheers,

Ben

 

 

I'll take a stab at your questions. I haven't built the full size SMT Dynalo, but have built a few of the mini Dynalo's, which are pretty much all SMT.

1. The resistors for the mini are all 0805 with the exception of the 20R, which were 1206. Vishay TNPW 0.1% 25ppm were used for most. I'm not sure on sizes for this version however.
2. Kevin's schematics typically do not show power rail bypassing on them. Follow the board values.
3. These appear to be LEDs and not caps. Kevin normally specs 1.7V red LEDs, such as Liteon LTL-307ELC.
4. I don't have a BOM for the full-size SMT version.
5. This project is still a very valid amp. Some would suggest the current feedback amp (CFA-2 or CFA-3), and I might concur with that opinion.

Be sure to use the golden reference power supply (GRLV) as well, as it is very good and makes a difference.

Thanks for the pointers Pars - I had overlooked the LED's on the Schematics (too many hours staring at the screen!)

I will take a look at the CFA projects and see which way I go. I was going to use either the GRLV of a sigma22 power supply, the sigma 22 is easy as there are kits available "off the shelf" but kinda makes sense to go with the GRLV to keep everything the "same"

One vote for the CFA/GRLV.

Just go for tube ubal/bal->bal and 4xCFA2's like a real man.

I've been using a pream based on the ubal/bal and four cfa for my headphones. 

It is one of the amps I feel most satisfied. 

Can you get genuine MPSW06 / MPSW56 output devices? These have been discontinued for some time and likely that ones you might find could/would be fakes. The power supply on that board isn't as good as a GRLV is also. And the layout of that PCB certainly isn't Kevin's. It probably seems all neat and tidy to have everything on one PCB, but that isn't always the case.

As has been mentioned by several users here, the CFA2 or CFA3 current feedback amps are probably more recommended here over the dynalo. Current part availability as well.

This thread:

The SS dynalo (balanced) can be built with current surface mount PZTA output devices (the more recent boards), but I personally would go for the current feedback amp instead.

Getting boards run is generally so cheap these days thru places like seeedstudio, etc. that waiting for a group buy unless it is something special (large board or boards, heavy copper, etc.) isn't really necessary. Someone may have boards available as well, but in general, I stay away from ebay or aliexpress. There are a number of chinese copies of Kevin's boards, using his gerbers, which he generally doesn't seem to mind (and he is aware of them), so I guess as long as it is a quality run, there shouldn't be a problem with them.

if they are just making boards from the gerbers, i'm fine with that. But the people taking the gerbers and then re-editing the hell out of them causing all sorts of issues (like taking all the values off the resistors) or making clone boards like the one above that require obsolete parts are just causing people trouble. find the gerber you want and have boards made.

Lol the above board seems to incorporate amb's sigma22))

Unlike Kevin, Ti is definitely not happy when this happens))

Edited August 10, 20205 yr by Helium

What type of caps should I use for the caps I circled in red?

 

 

Edited September 26, 20205 yr by sbelyo

Those 4.7uf are power supply bypass capacitors. The 4.7uf paralleled the 100uf electrolytic caps. I use some WIMA PP caps with appropriate voltage rating.

And I used multiplayer ceramic caps for the .1uf. 

Edited September 26, 20205 yr by mwl168

I can't seem to find Wima PP that fit at Digikey or Mouser.  I can find PET though, will these work?

https://www.mouser.com/ProductDetail/WIMA/MKS2B044701K00JC00?qs=sJjjjplDs9usMRoEQsMxiQ%3D%3D

I think any good quality film capacitor, including the one in your link, should do fine.

 

Got it...  I see Pars left them unpopulated

Put solid-polymer caps with appropriate diameter at a 100 uF places and PP/PE caps can be left unpopulated.

These are the Wimas I had in my BOM for the 4.7uf caps:

MKS2C044701M00JSSD

The solid polymer cap might be interesting as well. I hadn't realized they make these that large these days. Something like these 63SXE100M Panasonics or these HHSD630ELL101MJC5S UCCs could work.

 

EDIT: IIRC, some variants of the boards were missing the ground plane connection to one or more of these caps, so check that as well.

And you would never find polypropylene (PP) caps this large of value/voltage rating in something small enough to fit here. A Wima MKP4 cap of this value has a 27.5mm lead spacing.

Edited September 27, 20205 yr by Pars

Yeah, I realized that about the PP 4.7uf early on, just thought I was missing something.  I'll swap the electrolytics out for these https://www.mouser.com/ProductDetail/667-63SXE100M

So I can definitely leave the 4.7uf film caps unpopulated then?

The solid polymer cap might be interesting as well. I hadn't realized they make these that large these days.

Nichikon NU and L8 series are in most interest due to voltage rating up to 63 V with more than good ESR and more than enough capacitance.

So I can definitely leave the 4.7uf film caps unpopulated then?

Yes.

Finished the BOM, I'm pretty sure I got it all.  This is for one board.

Take a look and let me know if I missed anything or there are better part choices

Dynalo MkII 1.2 Mouser.xls

I noticed that some are using a better quality resistor for the 20R.  I was thinking of using Takman in this spot.  Does it pay to use something like Takman or PRP in this spot?

Two comments to the BoM:

- Your LEDs are listed with a 2.1V drop. As Pars mentioned higher up in the thread you should normally use 1.7V for Kevin's designs (LTL-307ELC)

- Can't remember the spacing for the 5pF capacitors, but I believe I used a high-voltage ceramic (75-561R10TCCV50) for this (also for the dynalo, although my boards are a different version).

 

You're right, I had wondered if those LED's were wrong.  I've swapped them for what you posted.  For the 5pF I believe it's 5mm but will measure again tonight.

Back when I built the original Dynahi I had to swap out LED's to get the lowest offset IIRC.  Is that the case here?

The 5pf caps I had in my BOM were Mica (598-CD17CD050DO3). Kevin's BOM (old one) used COG ceramics (81-RDE5C1H5R0C0K1H3B).

As for the 20R resistors, try them as long as they are appropriately sized. I'm not too much of a fan of the PRPs anymore (coating comes off easily). Never used Takmans. I've been using the Vishay/BC MRS25s for some stuff and have liked them.