The Multi Amp aka Dynalo Mk2

[gepardcv]

This is so interesting. The full-size Dynalos I built are the coolest-running amps I have. Really surprised at how much hotter all the smaller parts end up. I want to make a mini, but the heat issue worries me. 

[Pars]

My full size SS Dynalo (thru hole MPSW parts) runs fairly warm at 17-19mA bias, but nothing like mini warm. I haven't cased it yet (this winter), so I'll see what it is like when cased.

Here is the link to the spreadsheet I created for tracking what users are using for bias and what kind of heat they are seeing:

https://docs.google.com/spreadsheets/d/1D5LDuRdupZRoWR-GfAd03fkFSBAMY4-E_VcYfCAI1Z0/edit?usp=sharing

I don't know if HC allows sigs or not, as I thought if they did I would put the link there so it didn't keep getting buried.

Edited February 2, 2019 by Pars

[rumina]

my two smd amps with bivar leds running at 20 volts and led vf 1.71 volt, i also would go down a tad with the bias to around 15ma. second one (the one in your list) with 16.5 ma / 81c max after 2 hours - ok but on the edge. so i would use next time r14/29 around 210 ohm for bivar leds and 402 ohm r1/r3.

this is my second one, a lot of holes top and bottom, printed front and rear, whitout potentiometer, additional 4.4mm output. i use this one for travel together with a dap:

my first amp only with small heatsink in the group buy case  (with r14/29 240 ohm) was around 100c max and even discolored the pcb a bit. more holes  (best over 4mm diameter) and a heatsink lowered the temp to around 80c. if they get hot the bias rise quite fast even when the start bias is relative ok or low.

but i love them, like the sound better then my big dynalo, i now use on both  from trendsetter - linear integrated systems matched lsk489 lsj689 jfets.

Edited February 2, 2019 by rumina
typo

[Kerry]

I like the case.  Where did you get it?

[rumina]

this is the case i used:

https://de.aliexpress.com/item/143-40-4-180mm-WxH-D-aluminium-elektronik-pcb-geh-use-6063-extrusion-fall/32857644347.html?aff_platform=api&cpt=1549182007927&sk=ZVxRRvI&aff_trace_key=807df99551d348b39035d168c5f73204-1549182007927-05033-ZVxRRvI&terminal_id=1183572cd19e4eb0be580194ccaeaa77

the pcb slides in the grooves (some tap around the edge for isolation). but you need make some place for the top cinch connector (grind the topcase a bit with a dremel or similar tool, shorten the silver latch). then do the same thing for the two caps underneat he pcb, they need 2 mm more space on the side of the pcb. now you can slide in the pcb from the top (not sliding the pcb in) in the groove opposite the caps underneat, push down and the pcb holds in place.

for the topcase to fit you need to grind down the ac socket a bit, easy done with a dremel.

due the case is a tad longer then the pcb i printed two case holder plates that hold the pcb in place, so you can also use the orginal alluminum plates, sadly the topplate is realy thick and i was to lazy and printed the two top plates also.

i attache the freecad files and stl files so everyone can use them (missing are the holes for the pot/4.4mm plug and vents if you need them, easy to add).

the case is thight but works fine with some work and patience, take care of the heat, venting is not easy for this case.

 

 

smd_dynalo_roundcase_front_back_v2.zip

Edited February 3, 2019 by rumina
update link for the case / corrected 3d files use v2

[JoaMat]

Nice! and thanks for files.

[mdr30]

On 2/2/2019 at 5:27 PM, gepardcv said:

This is so interesting. The full-size Dynalos I built are the coolest-running amps I have. Really surprised at how much hotter all the smaller parts end up. I want to make a mini, but the heat issue worries me. 

 

On 2/2/2019 at 6:54 PM, Pars said:

My full size SS Dynalo (thru hole MPSW parts) runs fairly warm at 17-19mA bias, but nothing like mini warm. I haven't cased it yet (this winter), so I'll see what it is like when cased.

Here is the link to the spreadsheet I created for tracking what users are using for bias and what kind of heat they are seeing:

https://docs.google.com/spreadsheets/d/1D5LDuRdupZRoWR-GfAd03fkFSBAMY4-E_VcYfCAI1Z0/edit?usp=sharing

I don't know if HC allows sigs or not, as I thought if they did I would put the link there so it didn't keep getting buried.

My normal smd Dynalo got purrty hot with 400 ohm bias resistors. Lid on the Economica got almost too hot to touch in a cramped shelf but it worked a couple of years until one of the boards smoked.

Replaced components (mostly resistors, some smd:s) and changed to 255 ohm resistors but again smoke - the board had burned through someplace.

Thanks to the ever resourceful MLA I got a new board that I populated with the assistance of Spritzer (supplying PZTA06:s). Boy, now it sings.

Initially it didn't feel right to play with the volume at 5 but now I prefer it - it's here all amps should operate.

 

[G600]

Have you tried it with FETs instead of THAT340 ?

[Pars]

The link in the post from me quoted above was intended for Dynalo Minis only. Also, I never thought that stacking the amp boards like that was a good idea from a heat perspective.

[mdr30]

7 hours ago, G600 said:

Have you tried it with FETs instead of THAT340 ?

No, but have been tempted. Has its pros and cons.

[Pars]

What cons?


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[mdr30]

7 hours ago, Pars said:

What cons?


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Finding and matching them. If anyone got spares, pm me.

[jose]

Well, that's not a cons. Finding the components is complicated but still possible. You can get 170/74 of Linear Sis. for example 

[Whitigir]

Lol...I never changed my Bias, and I just accidentally left the Mini on the whole evening + last night....this morning it blew my mind.  She is still healthy 

 

for a moment, I thought she was going to go nuclear meltdown hah! 

[Shadowilla]

Hi guys, long time lurker from Chile and finally got the courage to build my own rig.

I want to build a Dynalo and didn't want to open another thread so I'm asking some questions here. If I'm doing something wrong please tell me, I tried to find forum rules without any luck.

I have a pair of Grados 225i (and a pair of all-terrain Koss KSC75), both low impedance headphones. I've never made a DIY amplifier before but I know my way around with electronics, soldering, reading schematics, etc. My knowledge of electronics is a little rusty (regarding calculations mostly), but is part of my curriculum (electrical engineer, although lately my job has to do with lighting industry).

I thought I'd start with a CMoy but I don't need portability and doesn't seem to be too HiFi for my needs. At home I use my NAD amplifier when I'm listening my CD player, TT, etc, but I want to build something for my work/desktop PC. Although I've always have the doubt if a dedicated Headphone amplifier would make a difference vs a big ol' amp...?

So the next one on the list was the Dynalo, and I've been reading for days through all the pages of this topic (and other forums, web pages, old KG site on wayback machine, etc), but since there's a lot of info, some questions arised:

1. I want the Dynalo for my unbalanced Grado with 3.5 and/or 6.35mm outputs; and to use with unbalanced RCA input(s). Is SSDynalo the best option or should I look into something else? I see that it has balanced in/outputs and don't want to build an overkill if I'm not going to use it (at least not yet).

2. What is the last version available of the SSDynalo (or the option you recommend)? Is there an updated BOM/schematics, etc available? (The info inside KG Drive is overwhelming)

3. I would like to use a through-hole version if possible. I know that is not the easiest build to start DIY, but I don't mind start this in a PCB prototype board, in order to later use printed PCB and nice case.

4. I intend to use Sigma22 to power this, since it doesn't seem to be complicated, but since all info is a little old, maybe there's something better and updated.

Those are my questions at the moment. Hope to find help to start this little project! I'm not old, but I'm at a point in my life that I'm starting to do all the "I'll do it later" things I have in mind.

 

Best regards!

[mwl168]

The SS Dynalo is really intended for both balanced input and output operations. The original Dynalo would have been a better choice for single end operation but I have not seen original Dynalo board being offered for many years.

If you have not already done so you can read up the current feed back amp (CFA) also designed by Kevin which would be a good option for single end operation.

As for PS, the Sigma22 is a solid choice. another option is Kevin's Golden Reference (GRLV) which many here has used to power their SS Dynalo, myself included. 

Edited March 18, 2019 by mwl168

[Shadowilla]

24 minutes ago, mwl168 said:

The SS Dynalo is really intended for both balanced input and output operations. The original Dynalo would have been a better choice for single end operation but I have not seen original Dynalo board being offered for many years. 

If you have not already done so you can read up the current feed back amp (CFA) also designed by Kevin which would be a good option for single end operation.

As for PS, the Sigma22 is a solid choice. another option is Kevin's Golden Reference (GRLV) which many here has used to power their SS Dynalo, myself included.  

That's what I feared. Original Dynalo only appears in older posts without any update on the boards or components I will look into CFA and the GRLV. Thanks for the info!

[Pars]

The SS Dynalo does support SE input, but without wiring your headphones for balanced output, you would be wasting 1/2 of the amplifier sections by using a SE output.
There was someone on eBay who sold a reasonably priced Dynalo (Kevin even bought one, or at least commented on it, but I don’t remember who the seller was and don’t see it now.


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[Shadowilla]

Yes, that's why I asked, being leaded b the old Dynalo -_-. I had high hopes that I had a chance to find it updated. But I'll check CFA mentioned by mwl168. Thanks for your comments!

[Pars]

You could go ahead and build the SS Dynalo and rewire your Grados for balanced (that part should be easy as you should already have 4 wires). Make up some balanced to unbalanced adapters to take the 4 pin XLR you would use back to either (or both) a 3.5mm and 1/4” TRS plug.

This place is all about overkill after all.

 

 

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[jose]

1 hour ago, Pars said:

You could go ahead and build the SS Dynalo and rewrite your Grados for balanced (that part should be easy as you should already have 4 wires). 

They would be the first Grados to reach Mars 

[montanari]

On 8/20/2018 at 2:40 AM, Pars said:

Another one lives... thanks to cspirou and his case GB!

 

 

I would like one of these, but I m not able to build it

somebody could help me or sells one directly?

thank you

Dani

[Pars]

6 hours ago, montanari said:

I would like one of these, but I m not able to build it

somebody could help me or sells one directly?

thank you

Dani

Not being able to build one yourself is a problem.

As for one already built, they rarely, if ever, come up for sale.

Commercially, the closest thing(s) to it are Headamp Gilmore Lite or Justin's new Headamp GSX Mini Balanced. Note that the Gilmore Lite is single-ended only.

[montanari]

I tried the gilmore lite didn t like very much, but maybe needed more time to understand it properly..

i would like xrl e single ended in and out, can I kindly ask you if you can build one?

[Pars]

I could consider it. I don't have any cases, so would have to have one made. If you wanted the TKD version, I would have to get a board and the TKD pot as well. As well as all of the other parts (not a problem), so not cheap.

What if you don't like it?