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Rudi_Ratlos 22nd April 2011 10:47 AM

1 Attachment(s)
Some time ago my friend Joe asked me, if I would like and design an AMP with 2 pairs of TO-3 output transistors.

Both, Joe and I, have a couple of MJ2119x transistors at hand, which are worth to be used.

I studied some of the DIY - AMPs in this forum and felt, that Michael Bittner's SYMASYM would be the best match to do the job.

I transferred his SYMASYM version 5.3 into EAGLE, did not change anything in the frontend, but added the pairs of TO-3 in the backend.
DADOD (thank you very much!) simulated the resulting AMP in LTSpice: the results look perfect!

I have attached the schematics as a PDF-file.

After finishing the layout, I had some space left on the bottom right and left side of the PCB and implemented a standard capacitor-multiplier
for the frontend there.

This is the resulting layout:

The red lines indicate tracks, that are running on the top side.
The TO-3s will be mounted on ALU-brackets.
The size of the PCB is 150 x 100mm.

Joe and I want the PCBs to be etched professionally, having the same quality as the PCBs, that I offered in my group-buys
for Carlos Mergulhao's DX Blame (see the picture below).

Since the SYMASYM, the backend and the capacitor-multipliers are proven circuits, we won't do prototyping.

In order to get a decent (about 13€ per PCB) price from the etching company, I must order at least 10 PCBs.

Maybe some of you like this design (SYMASYM with TO-3) and join the party.
I am sure, it will give you a big bang for your bucks.
Take a careful look at the schematics then and tell me, if I shall change anything.

Best regards - Rudi_Ratlos

pinkmouse 22nd April 2011 10:52 AM

Nice project! However, the combination of rounded and angled traces does jar a little. ;)

Rudi_Ratlos 22nd April 2011 10:57 AM

I will do some final cosmetics to the layout, be sure!

Best regards - Rudi_Ratlos

pinkmouse 22nd April 2011 11:01 AM

Yeah, I know. I frequently spend longer tidying up cosmetic stuff than working out the actual layout. :)

metal 22nd April 2011 04:29 PM

3 Attachment(s)
Thanks to Rudi who created the asc file and sent the other models included in his asc file.

Neutrality 1st May 2011 10:53 AM

Nice layout.

Rudi_Ratlos 11th May 2011 10:19 AM

I have just finished the "cosmetic improvements" of the layout and the silkscreen of the TO-3 SYMASYM - PCB.
Here it is:

Since there is some interest in the PCB in the German Analog-Forum, I will be able to order the minimum amount of PCBs.

Rich: are you still interested?

Best regards - Rudi_Ratlos

jmmartins 13th May 2011 08:25 AM


I'm also in for a couple of PCB's


digits 13th May 2011 08:45 AM

Rudi, I see you moved the traces there around the top left TO-3, I didn't like the first one, and the second one you got almost right. I see you now allowed space for the mounting screw, but if possible I suggest you bring the left trace back out to the side to reduce capacitance between the two traces, unless of coarse you think a little in that position is benneficial, other wise nice work. I know Carlos would drive you mad to get all those TO92 transistors in a row

Luke352 13th May 2011 10:36 AM

Do you have an idea on what postage would cost for a pair of boards to Australia? I may be interested in a pair.

Rudi_Ratlos 13th May 2011 11:08 AM


I will be able to offer you:

- the AMP PCB for 13€
- the DX PSU PCB for 7€
- the LSProt PCB for 5€

International shipping in coated letter is 5€.
If you pay via PAYPAL please add 4% PAYPAL cost.

The main group-buy thread is documented here (German Analog Forum - have a look at the pictures):

I will close the group-buy next week.

Best regards - Rudi_Ratlos

Rudi_Ratlos 16th May 2011 07:17 AM

This group-buy is closed now.
The interest in these PCBs has not been big in this forum, but I have a lot of orders from the German DIY forum.

Yesterday night I rendered the PCB with EAGLE3D and Povray(though some components are still missing).

This is, how the PCB will finally look like:


Best regards - Rudi_Ratlos

Rudi_Ratlos 18th June 2011 01:05 PM

This is the result:

Isn't this PCB a beauty?

I did not apply power yet, but I am sure, it will sound as good as it looks.

Best regards - Rudi_Ratlos

meanman1964 18th June 2011 03:05 PM

Rudi,very nice ,clean and ordered layout.

Rudi_Ratlos 29th July 2011 04:03 PM

The 1st round of my TO-3 SYMASYM group-buy has been an incredible success in Germany.
This version includes a Cap-multiplier for the frontend and uses 2 pairs of TO-3s on the output.

The German DIYers like to build mono-blocks, and here is an example, how the TO-3 SYMASYM has been set up by one of them:

There has been one flaw concerning my design (the power dissipation of the driver transistors), and I did a few minor corrections
(after simulating them thoroughly) on the schematics and mounted the drivers on the L-profile as well.

Have a look at the resulting version 2 - layout:

The red pads and tracks are showing the copper pads and tracks on the top-side of the PCB.

The layout, PCB - quality and sound of this amp is unmatched. I do currently not see any rival to this amp.

My TO-3 SYMASYM is not only a hommage to TO-3 transistors; this AMP "plays" music.

I will offer a very limited edition (a "Small Kit", consisting of PCB, TO-3s, MPC74 emitter resistors and ALU-L Profile) - the TO-3 SYMASYM LE -
by the end of August.
The price of a small kit will be very fair.

Best regards - Rudi_Ratlos

dadod 3rd August 2011 10:45 AM


Originally Posted by Rudi_Ratlos (

The layout, PCB - quality and sound of this amp is unmatched. I do currently not see any rival to this amp.

Best regards - Rudi_Ratlos

This is quite a statement. Can you explain why is this the best amp of all?

RKH 4th August 2011 03:08 PM

I am interested in one of your "small" symasym kits. Please add me to your list.


Rudi_Ratlos 4th August 2011 05:16 PM

...why is this the best amp of all?

I did not use these words, Damir, and I did not say:" ... sounds better than ..."

I emphasized the quality of the PCB, the elegant layout - approved by my layout-mentor -that took many, many hours to do,
resulting in vivid, smooth tracks, clear distinction between Power- and Signal-tracks, take - off points, where they should be,
the beautiful "TO-3 SYMASYM Builder's Manual", ..., and the sound.

I did some small enhancements on Michael Bittner's original design (added a CAP-multiplier for the front-end, for example), but
maybe it is the synergy of his folded cascode structure, his toughly coupled feedback and TO-3 transistors on the output that
produces a sound: power and dynamics, more than you can bear, smooth, with a timbre that you feel like in heaven,
a feast for your ears.

I will give you another example.
You listen to a "bootstrapped" AMP (I do not tell you the name of his designer) and you say: "Well - it sounds allright."
Listen to the same AMP having original, non-fake SANKEN 2SA1216 / 2SC2922 on the output - and you will not stop listening.

This is, what counts "in my ears": to have the chance to "listen to an event".

The TO-3 SYMASYM, having two pairs of MJ21193/MJ21194 on the output, is such an "event", and it is simply the best.

RYAN: you are in for 2 small kits.

Best regards - Rudi_Ratlos

dadod 4th August 2011 07:25 PM

I see Rudi what you whant to say, just be careful when you state
" I do currently not see any rival to this amp."
This is in a way as DX amps are descibed and it's preposterous.
I am sure the PCB is exelent and the support too. Original SYMASIM uses faster output transistor and technically it should be better. I would like to listen to both but it's no possible as I do not have them and no time to bild as I have other project in line.
I am fascinated how DIY in Germany is good, so many enthusiasts.
regards Damir

StevieK 6th August 2011 08:58 PM

Hello Rudi,

Im interested in 3 x 2 PCBs. Are they still aviable?

Rudi_Ratlos 8th August 2011 03:59 PM


I will make them available.

The price depends on how many orders I will receive.

The price will be 11, if I order 10 PCBs, it will be 9, if the quantity that I order exceeds 25 PCBs.

I have closed the German group-buy 2 weeks ago, expect the PCBs to arrive by the end of this week and will wait for the first feedbacks of the German DIYers, until I will offer these PCBs in this forum as well.

Best regards - Rudi_Ratlos

Rudi_Ratlos 12th August 2011 07:12 PM


I received the PCBs from the etching company today.
They look beautiful and precious.

Here it is:

Best regards - Rudi_Ratlos

loek 13th August 2011 02:12 PM

Red is beautifullllllll.

Rudi_Ratlos 13th August 2011 02:56 PM

Yes, Loek!

Red: is the colour of love, of emotion, of blood -is the colour of sound!

Best regards - Rudi_Ratlos

John Luckins 18th August 2011 01:56 PM

Hi Rudi,

I like the design of this amp a lot and much prefer the T03 devices. Local decoupling of these, the Cap multipliers and good layout round it off nicely.

Do you think you could please put me down for 4 Boards when they become available. The plan is for 2 X Bridged monoblocks.

Regards and thanks


Rudi_Ratlos 19th August 2011 02:52 PM

My German DIY - friends have already begun to assemble the beautiful TO-3 SYMASM PCB - Round#2:

I still wait, until a couple of them have successfully finished their build and say: "Whow: what a beautiful sound!".

Best regards - Rudi_Ratlos

digits 19th August 2011 03:47 PM

Nice work Rudi, sadly Red is also the colour of my bank balance this month.

Rudi_Ratlos 29th August 2011 05:12 PM

I am very happy (and a little bit proud) to tell you that I received several very positive feedbacks of my German DIY - friends.

The TO-3 SYMASYM V2 - PCB that I offered them is perfect.
It is absolutely error-free (!), and - what is more important -: this AMP "can play (with) your music."
It is praised for its silk highs, mature, real midranges and controlled, black bass.

I will offer this PCB to you now: the group-buy for the TO-3 SYMASYM V2 is open!

I (!) cannot compete with the technological skills of the Brazilian or Australian AMP Guru, offering AMP PCBs currently as well!

But the TO-3 SYMASYM can compete with their creations! I am absolutely sure about this!
The SYMASYM has been designed by Michael Bittner.

Refer to this thread please:

I merely changed the output to include a pair of TO-3s (my hommage to the TO-3 sound).
(Rumours have it that OnSemi will discontinue the production of TO-3s.)

I also included CAP-multipliers with clipping diodes, so that my TO-3 SYMASYM can be operated from a wide range of transformers,
and layouted it on PCBs with the best quality that you can imagine.

This is the result:

You can go for it!

What will I offer you?

A PCB with the best available quality (2mm FR4 PCB, plated-through holes, 70m copper tracks, covered with gold immersion,
proven layout, ..., simply: perfect),
the TO-3 SYMASYM Builder's Manual, the BoM, the needed 4 pairs of output-transistors (MJ21193/MJ21194) for the 1st three of you,
who want to have, ... and an incredibly life, real and beautiful sound.

The price?

11€ per PCB if I receive orders for less than 10PCBs (that would be a shame) , 9€ per PCB, if I receive orders for more than 25 PCBs.

Shipment is: 3.45€ worldwide.

Best regards - Rudi_Ratlos

andreasw 29th August 2011 09:22 PM

Hello Rudi,

I will take 2 PCB.

Best regards

John Luckins 30th August 2011 08:50 AM

Great news Rudi, congratulations.

I'll go for the 4 boards (as requested in post 25 above)

Thanks and regards


dasch 30th August 2011 02:24 PM

Hello Rudi,

please add 7 PCBs to your list.


gig 30th August 2011 02:55 PM

Great job Rudi. I'm in for 2 boards.
Also interested in the "small kit" mentioned on post #15 and/or in output transistors for a stereo set, if available. Can you please send me cost details?

Thanks and regards

Albundi 30th August 2011 03:35 PM

Hello Rudi,
I am interested in one of your "small" symasym kits. Please add me to your list.


Rudi_Ratlos 30th August 2011 04:43 PM

Thank you very much for your interest, gentlemen!

Since I have been asked, I will offer you as well:

1) a PSU PCB
The size of the PSU - PCB is: 125 x 85mm.

2) a Speaker Protection PCB
The size of the LSProt - PCB is: 68 x 39mm. You need one PCB per speaker.

...and ...

3) a Soft-Power-On PCB
The size of the SPO-PCB is 100 x 65mm.

I will give you further details on these PCBs later on.
All of these PCBs have supreme quality and are 100% approved.
(I prototyped the Soft-Power-On PCB but did not yet have it etched professionally.)

@Gig: I will not offer the "small kit" (consisting of TO-3s, emitter resistors, ALU-L profiles, ...), because the kit will increase the shipping costs immensely!

There is only one drawback concerning my offer (and I am a little sad about this):
Once you have listened to my TO-3 SYMASYM, you will no more visit this forum, you will no more look at my current creations, ...

"You will have found your sound."

This is the current "interested party list":

Best regards - Rudi_Ratlos

sas 30th August 2011 05:23 PM

Hello Rudi,

I was so badly hoping there would be another round...

Please put another 4 TO-3 Symasym PCBs on your list for me.

I am impressed with the effort you put up to supply us with these lovely boards!
Keep up the good work!


Rudi_Ratlos 30th August 2011 06:15 PM

Is that really you, Sascha?

Since it is raining "cats and dogs" in Hamburg, I took my time to complete the 2nd channel of my own TO-3 SYMASYM.

I drilled the ALU-L profiles for my PCB (this is how I do it- I will give you the drill-pattern as well):

and started to solder the BD139 - Tempco and the TO-3s:

Do not worry, gentlemen!

You do not have to assemble a complicated heatsink like I have done!

Your Version 2 - PCBs will have the drivers sitting on the ALU-L profile!
Have a Look at post #28! Your PCBs will be "perfect"!

But: isn't DIY beautiful? To saw, to drill, to solder, ..., and finally listen to an AMP like this, "to YOUR AMP"?

Best regards - Rudi_Ratlos

sas 30th August 2011 07:07 PM

Hello Rudi,

If you mean Sascha from the german AAA-Forum I have to disappoint you.

I have thought about buying all TO-92 transistors (plus a lot extra for matching) off digikey since they have all the needed small signal transistors (including MPSA18) from ON-semi in stock.
Its quite a bit dearer of course compared to the parts that you and I guess most of our german fellows have bought from Reichelt.

But would the extra cost be worth going for ONs?

(The other) Sascha ;)

curryman 30th August 2011 08:22 PM

Hello Rudi,

please put me on your list for 2 SYMASYM Boards and 2 PSU PCBs.

Will they also run from 2x18V AC? Have some 300VA trafos lying around...

best regards, Daniel

andreasw 30th August 2011 10:14 PM

Hello Rudi,

please add 2 PSU PCBs for me as well.

Best regards


RKH 31st August 2011 12:34 AM

I ordered my from Rudi a while back and I neglected to confirm their arrival in Colorado USA. As usual, these boards are beautiful and high quality. As is Rudi's packing and parts. THANK YOU RUDI!! :up:


tome 31st August 2011 09:54 AM

hi Rudi
Please put me on list for foloving boards:
2 - symasym amp boards
4 - psu boards
2 - ls protect boards
2 - soft power - on boards
thanks and regards

WolleMusic 31st August 2011 02:22 PM

Hello Rudi,

please put me on your list for the following boards:
2 SYMASYM Boards
2 LS protect Boards

best regards

Rudi_Ratlos 31st August 2011 03:43 PM


You asked: Will they also run from 2x18V AC?

Michael Bittner's SYMASYM was designed and tested using 25 VAC transformers. He recommends DC values in the range of +/- 35 V and +/- 40 V.

Please refer to this thread, if you want to know more about the SYMASYM:

Maybe 18 VAC will work. You have to change several things, though, and it may end up being a bad sounding amplifer.

So: my short answer is: NO.

Best regards - Rudi_Ratlos

meanman1964 31st August 2011 05:25 PM

For me also two amp boards

Rudi_Ratlos 1st September 2011 05:57 PM

Dear TO-3 SYMASYM friends,

tonight I did the 1st power-on on my 2nd channel of my TO-3 - SYMASYM-PCB.

Since my eyes do no more have the capabilities of a hawk, I took my 7 MB digital camera, made a picture of the solder-side of my PCB
and verified that I did a good job.

This looks quite good!

Then I went downstairs, connected the PCB to my PSU, installed 10 Ohm resistors across the empty fuse-holders, shortened the RCA input, ... and ... powered on.

No smoke?!!

Well: this is what I expected.

Then I turned the trim-potentiometer for the TEMPCO / BIAS - adjustment counter-clockwise, and turned, and turned, ..., nothing happened,
..., and turned and turned - then, all of a sudden: the DMM reads: 1 mV dropping across both TO-3 emitter resistors, 2 mV, 3 mV, ...
the 10 Ohm resistors are about getting very hot, ... - it works!!! :cheers:

I have documented the procedure how to adjust the quiescent current in my "TO-3 SYMASYM Builder's Manual".

Be sure: this is a very, very outstanding AMP.

Best regards - Rudi_Ratlos

Leatherface 3rd September 2011 01:18 PM

Hello Rudi,

I've missed your last GB in the AAA so I'm glad to reach another one here.
Please add 7 x TO3-SYMASYM, 7 x PSU and 7 x LSProt - PCBs on your list.

Thanks and regards,


AndrewT 3rd September 2011 01:40 PM

Monitor the voltage across the Vbe multiplier, as well as Vre.

You will see the Vbe varying instantly in response to turning VR.
Then as Vbe approaches the output bias voltage required you can expect to see Vre starting to take off.

4 soldered in loops, for tapping in test instruments, makes a big difference when developing a new amp.

Why do you still use the remote server to hold our pics?

RKH 4th September 2011 01:01 AM

Hi Rudi,
Do you have an English version of : ""TO-3 SYMASYM Builder's Manual".?

I have the German version, but my German is rusty.


Rudi_Ratlos 4th September 2011 08:58 AM


please use an "INTERNET translator" (GOOGLE's translator, for example).
Divide the WORD-Document in several chunks first.
It is too big to translate it as a whole.

The result is quite good!

Best regards - Rudi_Ratlos

Rudi_Ratlos 4th September 2011 09:45 AM

This is an update of the current order:

I will close this group-buy as soon as I have received Rudi_SW's order.

I sent Rudi_SW a parcel with quite a number of PCBs, TO-3 transistors, emitter-resistors, ..., some time ago, but his parcel got lost.
I filed a request for investigation then, but DHL cannot tell me, where his parcel has gone.
I am now struggling with DHL to refund the parcel's worth.

I advice everybody to spend some extra and ask for insured shipment.

Due to the fact that I do no more have to pay the tooling costs and due to the quantity of PCBs ordered ,
I will be able to offer you the PCBs for a lower price than given above.

This is the current status of my own build:

Remember: these are the Version I - PCBs.
The Version II - PCBs (the ones that are offered in this group-buy) have the drivers mounted on the ALU-L profile!

Best regards - Rudi_Ratlos

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