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TO-3 SYMASYM

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#921
@Fabian:

I have built a TO3-SYMASYM for a friend of mine a month ago using very expensive PRP-resistors (see image attached).
A PRP-resistor costs about 40cents (as compared to a 4cent-resistor, being offered by REICHELT, produced by YAGEO (formerly: VITROOHM), rated at 1% precision).

I did not hear the least audible difference, compared to my own REICHELT-resistor TO3-SYMASYM.

Best regards - Rudi
 

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#923
@willNamennichtnennen:

This is the way I do it (see attached image).

I do not solder the input-differential pair of transistors directly into the PCB but use a 6-pin IC socket (you have to cut it, of course!) and insert the transistors into this socket (be aware of the orientation of the transistors!).

Then I will use whatever transistor sweets my ears at its best.

Best regards - Rudi

P.S.: You will get very well matched 2SK170BL from here, for example:
http://www.ebay.de/itm/2SK170BL-Toshiba-matched-Quad-/371120382727?pt=Bauteile&hash=item56687fa307
 

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#924
If I remember correctly, you still have a Symasym working? As I am currently moving from Munich to Nurnberg, I have no time in organizing a GB for Badel Trafos right now. But if you guys are not in a hurry, I could do it in around 4-6 weeks. As I stated before, the Trafo has 400VA with 2 Secondaries, so in total 4x 25V. Weight is somewhere around 5 - 6kg, so I am not quite sure about shipping around the world. "Extras" or "Schickimicki" as Rudi called it are:

- Low Inductance
- Schirmwicklung (no clue about the english word)
- magnetic shield
- completely in cup

I could ask at Badel for pricing groups so we get an idea.

For resistors: yeah I know Rudi. I built my first Symasym Monos in 3 different Versions, all with the same standard Panasonic / Wima Caps. First block was Reichelt Resistors, Second one was Takman, Third one was Vishay CMF. From my subjective listening: No1 /2 no difference, subjectively a little more lively sound on the Vishay CMF SAS. Most impact was exchanging the WIMA FKS with MKP1839 MKPs Vishay Roedersteins and the electrolytics. Though, its not perfect... there has to be more deepness in sound, thats why I have "big plans" with this Symasym ;-)

My plan for this new Black Beauty:

- Vishay CN60 where possible, rather good to source them, only 0,25 € per piece
- 100nf Caps totally Vishay Roederstein MKP1839 (will be a tight fit in some locations), not yet sure about the other foil resistors but they will for sure be PP, nothing else
- The 4 0,22 / 5W Resistors will be replaced by Isabellenhütte PHB Managanin Resistors. Those are real cuties, 3W standard / 10W with cooling fins.
- Silver Micas for Mica Caps

Open questions are still: Electrolytic Capacitors... I am really bad in making decisions here... For sure its not going to be some boutique stuff like Black Gate / Mundorf / Daelund stuff. I was thinking about Nichicons / Elna (Silmic II / Cerafine) / Panasonic (FM / FC) ... definatelly need help here ;-)

Besides that: Wich Transistors should be matched? Besides the 2SK170BL's (and which Idss should be chosen here)

Regards,

Fabian
 
#928
Rudi_Ratlos said:
Gentlemen, Watchtmouse, WillNamennichtnennen:

I do currently have no Soft-Power-On PCBs at hand.
But I can order 10pcs. of the one shown in the attached image.

The size of the PCB is 90 x 69mm; its colour is green; its price is 4.50€ per PCB.
It can be used for 230VAC/50Hz (you need an EI30-1 transformer / 12VAC) as well as for 115VAC/60Hz (you need the TAMURA 2FD-212).

The schematic uses a LM555 timer module and 2 relays.
The top relay is closed as soon as the 7812 voltage regulator shows 12VDC on its output. At this time the current is limited by 2 NTCs (the shown values are a proposal).

As soon as the delay time (determined by the 100K resistor and 10µF capacitor - giving a delay of about 1.1sec) has expired, the bottom relay will close, bypass the NTCs and the mains current flows unhindered.

Best regards - Rudi
Click to expand...

Hi Rudy,

Payment is send, for the Symasym, Black Beauty PCB (NJW0281/NJW0302) thanks for the time invested in this version.

I am still interested to get some of your Soft-Power-On PCBs, I have the previous version of the DIYAudio store softstart, (the current DIYAudio store softstart PCB is too expensive, plus that I always have to travel Gelsenkirchen to collect the items from the Customs office(Zoll) since they moved the store completely to America)

I did modify the DIYAudio store softstart to use two of the ringkerntrafo.nl NTC instead of the resistors, this works good.

In parallel I am building some class A (F5T) amps, and for that I want to use your Soft-Power-On PCB
 
#930
Put me down for two sets

Please put me down for two sets

4 x Black Beauty PCB
4 x two Pairs of NJW0281/NJW0302
4 x four x 0R22 Resistor
4 x MKT1822/10µ + MKT1837 10nF
1 x Shipping to USA
Break the PCB's: Yes

Any word on the cases? They look great, perfect for this amp. Keep up the great
work.😀
 
#933
Payment sent. Thanks for your efforts Rudi.

I have written to Badel yesterday. Did not get an answer yet, but I asked for a quote if we get more transformers. As soon as i get the information I will post it here.

As for the electrolytics: did somebody already think about it?
 
#936
Rudi, in the BoM for the PSU, there seems to be a mistake if you did not alter the values of the resistors there.

You put in a 6K8 Resistors (1/2 W) instead of the 10K Resistor.

Do the 0R47 Resistors really have to be of the 2W type?

Regards,

Fabian
 
#938
You probably don't need a preamp.
Use a vol pot with DC blocking capacitors before and after the vol pot
Add RF filters at the input sockets.

Some of your quieter (low source voltage) may sound too quiet.
Try them with a temporary vol pot and the bare amplifier, BEFORE you buy or design the case/chassis layout.

If all your Sources play loud enough, then don't add another gain stage.
 
#939
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