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TO-3 SYMASYM

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#721
Wirehead.be said:
My SymAsym is nearing completion. Just waiting for the toroid and the multiplier cap transistors 🙂 Can't wait to fire this up and start working on the case 😀
An externally hosted image should be here but it was not working when we last tested it.
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Wirehead,
did you check the helix direction of the wire wound?
The wrap around coil should be wound in the same direction, else you will get some cancellation of the required inductance.
 
#723
Matched the 2SK170 LTP's - It's spot on now - both bias and DC offset. One channel has 4.6mV offset; the other one 0.5mV offset 🙂 Highly recommended, doesn't add much to the final price 🙂
 

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#724
I'm a couple years late to the SYMASYM party. 🙂 What's the status on availability of the PCBs for this amp/psu project? Are there any leftover, and if so, what's the price including shipping to the US?

Edit: Without reading all 73 pages of posts, is there post describing the specs somewhere? Give me the details! 🙂
 
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#728
Hi Rudi,

Is there any technical reason that says you had to use the 2SA1381 and 2SC3503 for the on-board CAP-multipler in the SyAsym boards ?

Is there some alternative to these transistors that could be acceptable without compromising the amp sound quality ? I have plenty of good old BD139 and BD140. They are fast and rugged. With a 25v-0-25V transformer feeding the SymAsym, I don't understand why I could not use them in the CAP-multiplier.

I ask because 😱 I don't want to get a burned 😱 amp ..., it occurs always when you don't know why something is done and you do some wrong (let's say) "improvement 🙄".

Thank you for your answer 😀
Best regards

rephil
 
#731
TO-3 revisited

In post #706, I did write that I did not hear tonal difference between the latest TO-3 system and a previous non TO-3 symasym system.

Today I must re-write this statement, the input was the cause that no difference could be heard (in post #706 the source was of low quality).

The current session was with a DDDAC 1794 NOS DAC, here the TO-3 system had deeper bass and better overall performance as the non TO-3 symasym.

All credits to Rudi.

The TO-3 system is not at my place no more (makes you wonder why I did not test better), now the quest continues.

Grtz

Bert
 
#732
TO-3 Symasym up and running

I just finished this amp and have a couple of hours run time on it. It is extremely quiet (and I know as I have very noisy mains.) So far, good at low volume, very good at higher volume.

Apple lossless (iTunes w/PureMusic) --> Mac Mini (optical out) --> Cambridge Audio DACmagic --> Sansui CA2000 -->TO-3 SymaSym --> MJKing Open Baffle (Fostex Full Range and Eminence Alpha-15A)

Next up... I'm going to add my Aikido (with 6CG7s) pre-amp. Then I'll fold in my OPUS DAC etc.

Rudi's boards and build guide are the best!

By the way, I have a very big (800 VA) transformer so I'm using the DIYAudio softstart circuit as well.
 

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#733
Thank you for your kind words, Ryan.

The TO3-SYMASYM is - at least in my ears and the ears of those who built it - one of the highlights of this forum, and - believe me -
I have re-enigineered a lot of AMPs being presented in this forum.

The TO3-SYMASM is playing emotions, dynamics, deep black bass and smooth heights, producing the "Philly Sound" of the 80th.

I have - in the meanwhile - layouted a version, which is much more compact, but I wonder, if I will offer it as a group-buy.
Doing a group-buy means a very lot of work for me.

Best regards - Rudi
 

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#735
Rudi_Ratlos said:
Thank you for your kind words, Ryan.

The TO3-SYMASYM is - at least in my ears and the ears of those who built it - one of the highlights of this forum, and - believe me -
I have re-enigineered a lot of AMPs being presented in this forum.

The TO3-SYMASM is playing emotions, dynamics, deep black bass and smooth heights, producing the "Philly Sound" of the 80th.

I have - in the meanwhile - layouted a version, which is much more compact, but I wonder, if I will offer it as a group-buy.
Doing a group-buy means a very lot of work for me.

Best regards - Rudi
Click to expand...

Hi Rudi,

It is a very good idea to think to offer 🙂 this new release as a group-buy 😎. You have good ideas Rudi :king:!

So if you do a new group-buy, I am in for many of all boards you will provide.

I have great fun with the boards I have got from you : my SymAsym is slowly growing. Recently I got able 😀 to drill - as should be 😉 - the alu L profile in order to fit the TO3 devices, and until now this has been a no go for me. I have partly populated one board, and I have stil 😕 a few problems. Here it is.

BTW, did you try the MKT 1822 22uF with the SymAsym ? I have some problems with the MKT 1822 10uF : I have two of them, and they don't measure the same on my bridge this varying the test frequency. I am willing to fit the the MKT 1822 22uF as I have plenty of them home, and two of them that neasure the same in varying the frequency would be for me easy to get ... IMO the frequency measurement of this condensator has to do with the goodness of sound of the SymAsym.

The second problem is matching 😕 the output transistors. With what parameters did you do that ? I believe that it is at 55mA, getting the hFE within 5%. Did you get also the vBE within some (how much) mV for them ?

Thank you for your reply 🙂 😀.

Best regards

rephil
 
#736
@mcds: the PCB-layout already includes CAP-multipliers to provide smooth and stable voltages for the frontend, and the CAP-multipliers
are doing a very good job.
@Rephil: I measured my TO3s with a collector current of 100mA (adjusted by the CCS of my test-rig).
The main function of the input capacitor is to block DC voltage.
I myself am using a 3.3µF Vishay MKT.

Best regards - Rudi_Ratlos
 

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#737
Gentlemen, to offer you the current layout of the TO3-SYMASYM in a group-buy will cost a lot of money per PCB,
since the layout needs tooling costs!

But I will offer you a PDF-file of the solder-layer to "Do-it-Yourself".
The size of the PCB is 139,7 x 112,4 mm.
If you need further instructions, how to build: tell me.

Best regards - Rudi_Ratlos
 

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#738
Rudi_Ratlos said:
Gentlemen, to offer you the current layout of the TO3-SYMASYM in a group-buy will cost a lot of money per PCB,
since the layout needs tooling costs!

But I will offer you a PDF-file of the solder-layer to "Do-it-Yourself".
The size of the PCB is 139,7 x 112,4 mm.
If you need further instructions, how to build: tell me.

Best regards - Rudi_Ratlos
Click to expand...


Hi Rudi,

Thank you for this very nice gift. Yes I will give it a try later, but I will need also the silk screen in order to understand where the components are placed. Thank you Rudi !

It is again a very nice board that you :wiz: did !

BTW, I measured the TO3 that you provided matched to me : they are really very well matched : hFE difference <1% ! and the Vbe is also very good between pairs : difference <1mV ! How many transistors :yikes: did you measure in order to get such a good result ?

IMHO you could match at 50mA (I did do the measurement too) : the values of hFE are practically the same as for 100mA, the Vbe match the same as previously, obviously at other values.

Again thank you :santa: for your SymAsym and the boards and components I did get from you! I am more than happy 😀 to get soon a working SymAsym with all what you provided to us :cheers:.

Best regards

rephil
 
#740
Ooops

My amp went to the dark side. I don't know what precipitated things but I have a suspicion it started in my pre-amp.

Regardless, can someone give me some advice on how to diagnose and resurrect this amp?

Symptoms: Lots of crackling static on output.

Strategy:
check for shorts on output transistors and heatsink
check rail voltages
check bias settings
check output offset voltage...

From this point on I could use some help. I'm really disappointed that this happened. If the chain of events is as I suspect, it is totally my fault.

Thanks (in advance) for your help
Ryan
 
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