Symphony, the best of two worlds, joining Symasym from Bittner

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With the Dx Blame, that also came from Doctor Self, the Blameless.

I continue to search for perfection, even knowing this does not exist.

Friends have asked me to try to join the bass and dinamics from Symassym to the superb treble reproduction we have in the Blame...the low distortion too.

I have made (simulated only) the Symphony.

It uses the Symassym 5 input, a current sink was added.

The voltage amplifier is enhanced, Self style, and using the same differential alike style used by Bittner... the main difference is the second stage is feeded by bootstrap.

I have not assembled... i cannot do that now a days, i am still healing from a surgery..but i will do that and dead line will be Christmas....uncle Charlie's gift for the Dx Corporation friends.

I may use the Electrocompaniet idea to feed drivers using CCS, alike i did at Precision II and also in the published Troyan...but i have to listen with and without to evaluate that a little bit more.

Distortion is the smallest i have obtained..less than 0.0018% THD...but i have to see how this sounds and the harmonic distribution.

The amplifier is under research, the topologie will be the one shown, with drivers CCS or not.

The output power will be decided too.

Attached the Symassym schematic Bittner did...i would like to remember friends i have worked helping Bittner, and i know this amplifier performance very well, as it is well accepted by the forum, alike the Dx Blame..then i will join them together.




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at least in the simulator it works great..this seems there's a huge chance it will work real life.

Good luck Line up.



No doubt it works, thanks to the LIN kindness, but all the work
is made by half of the VAS..
The other half is not functionnal but don t stop the active part
from settling the DC loops correctly...

This is because the current mirror is NOT a voltage mirror,i.e,
the AC voltage amplitude is not the same in each leg of the current mirror..
Despite i have not tuned the Symphony..i have just make it work in the simulator

I have spent just one hour in front of the computer....but here you see it is a nice promisse of performance.... or course, if you believe small numbers know im not the one loves numbers..but some folks believes on them.

The Symphony was not tuned, so numbers will change, and i will make it better in distortion than the Dx Blame.

You can see the harmonic distribution and the THD up the page.... Omar have asked (Metal), so i have sent him something..but really, i had not worked on the Symphony to reduce these numbers..but i will do it... as i told you, there are several folks that believes good numbers represents good sonics....not always in my point of view..but sometimes this is truth...happened with the Blame..where good numbers resulted in good sonic too...but have not happened with the standard Dx amplifier, that sound great and distortion is high (0.023% THD)

The Symasym 5 had this same numbers when simulated... well... almost the same (0.021% THD)




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I already have much better simulation results, the unit was developed a lot

Some friends asked me to go ahead and not delay till the Christmas....i cannot...i have to wait people form group buy's to assemble..there are more than 90 guys in Brazil starting to assemble the Blame...i have to wait them finish before to release a new amplifier.

Also we have Rudi in this forum.... boards are arriving and i do not know if he will open a new turn to group buy or next monthes are the time needed to allow this people to build.

Because of that i will have time to tune it using calm... to test it with several speakers.

Simulators allow us to produce 20 different amplifiers each day...but untested and untuned things...i want to make it right!


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"Left half" of VAS (schematic in post 2) is without any function, outside signal path, connected only to +- Ub and GND. You can omit 3 transistors, 3 resistors and 1 capacitor, compensation capacitor should be in "right half" of VAS . And than it is "blameless"(without dif. input degradation) with bootstraped VAS. Or??
Only now I noted post 5 by wahab..
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Topologie is under research.... the removal of these parts resulted in

higher distortion.

Here is how it looks today.

But thanks by the input..left VAS half has not function as you said..but the removal resulted not least for a while.

I got what you mean... and i already have realised this...thank you BV.




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I will find a solution....but i already perceived too much Blameless

Not a good idea to make exactly as Blameless because i already did..also not a good idea to make alike Symasym.... this was already done.

I have another idea to explore.

Here is the topologie under research as plan B




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Not a good idea to make exactly as Blameless because i already did..also not a good idea to make alike Symasym.... this was already done.

I have another idea to explore.

Here is the topologie under research as plan B



It is drawn different , but it is APT1-like(level shifter topology).. with a extra differential (buffer). Harmon- Kardon buffers the 2 halves of the level shifter like you did(pix-below),but no cascode. Adding the cascode to the level shifter makes it faster and more stable (add a base stopper of 22-47R to that cascode).Also add Cdom to "upper" half of level shifter (one near positive rail). It is "balanced" like the sym (even better) ... which accounts for the very smooth midrange.
Go ahead , give it a build , It DOES have the bass (killer) plus the beautiful mids and highs (even better) than the sym. Play around , have fun .... you could get lucky ,too.
Believe me , no ill will ... only good advice. :)



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People asked me to make one, i am trying some ideas

at the simulator, but i will release only if i manage to produce a very different thing.

You see, there are several Symasym around... seems yours is very good...also there are some others not very good and i like the original one.

There are some Blameless around...also my Dx Blame is deeply inspired in Blameless...

I am doing, alike others, the old very song..... alike several folks...we are just doing the same style, the same amplifier....i am already thinking about and may not use Symasym as inspiration, as it was already deeply tuned and explored.

I may try something different... and by myself is important...i wanna do it by myself.

I had a third idea... and i am thinking about.... will not be symasym anymore...will have something that remembers the symasym only.

The Dx has the real bass..the first one...the standard...i may go back to the past to study.

You know, i have some ideas from the seventies and eigthies.... designer these old days had not the tools we have now a days.... also they had not simulators to help them and the surrounding sub circuits.... maybe i will try something old and give it a update.

You see.... Aksa 55 style we have several.... also Quasi we have variations...also Symassym.... also Blameless.... i will try something different.

Thank you anyway...your amplifier looks really good.


I do not know AndrewT... i will assemble the elected one

sometimes i can have an idea about the sonics just watching schematic and topologie..but sometimes not.

The harmonic distribution helps a lot.... avoiding some harmonics use to result fine..not the numbers, but the ratio, the distribution....seems good to my years....but there are other things to think about, even more important than THD.

The idea is to find something old.... designed when they had not their amplifier had 0.03 % THD or more..they had not help from simulators and modern practices... so, the idea is to apply more modern ways to do the surrounding sub circuits.... and to tune them at the simulator .. and finally to try some ideas directly in the prototype ugly board.

Crowdy circuits, alike i did at Troyan, proved to myself that does not sound very good...just good..not outstanding...some simple thing sometimes works better.

Well..... i have to use what i have as advantage compared to some other folks...this makes the difference.... i do imagine people make things pretty and had not courage anymore to go removing parts and to try different things not to mess with the board.... i do opposite...i start with a problems to me to go changing everything...and this works great this way... this is the difference...and i am showing folks the way i this is not a secret..everyone can have this "advantage" if decide to beat their own prejudices and their personnal limits.... accepting to mess with the amplifier while as prototype.

People asked me to do something even better than the Blame...i am not sure if i can do that.... really...if you wanna know, i do not think so.... the Blame sounded so nice to me that it is hard to imagine something even better.... well... at least to my ears.

Well...i gonna try.


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I have created the option C too.

Then i will decide.

In December i will release showing you prototype pictures, Alex mm will produce layout.... Renatovsky will produce boards and then you will have the Symphony.

So..... i will see you next Christmas.

Input not shown, values not defined, voltages not defined... supply voltage not defined yet...input is top secret..will show you Christmas.




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After several amplifiers studied, i understood this marriage will not be good

Also, there's are a lot of Symasym around, and version 5.3 is considered reason to make other, when we have a lot of them around.

I also could not make it nice in the simulator (numbers)... then i give up.

Also the mixing of them looks not a good idea when watching simulators..they are not "that" different related the way they work...Blame and Symasym...not so different...just some details... Symasym looks a blameless that received a make up..also blameless looks alike a Symasym after received a make up too.

Will try Dx Blame MKII.... and will not be inspired, or mixed, with Symasym anymore (already is....hehehehehe) and was not me that made this way...was before my first amplifier this was made that way..and i do not know the one made this way.... maybe Sansui as Hugh have perceived very fast, at the first moment he watched the topology.

To release in December, 24

That's what the Dx Corporation board members said..... so... will do this way.


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Yes... Wahab and forfun.... this schematic interests me

I will give it a try.

The members of the virtual Corporation counsil decided that i should produce the MKII...another i gonna do it too.

But, in parallel i will be studying these options.

Can you send me the complete schematic folks?

Now we have Ostripper with a good Symasym (alike and different) schematic...something alike in the topologie...some "Otala" style too.... but, in December, he may be already finished and only collecting orders in a group buy and then i can introduce another Symasym alike circuit... despite i do not like very much the idea.

But the Corporation Counsil, was a little bit splitted.... some wanted the Symasym alike...others wants MKII....and MKII has beated because the modifications suggested are interesting, as people will not loose their boards (150 have boards already)...

I may try know....i cannot publish an amplifier worst (in measurements) than Blame....because some folks strongly believe that numbers sounds....and sometimes this happens.... the Blame is a good example...sound great and clean..and measure fine my simulator the distortion is less than 0.002% THD (Multisim 10 - Professional version)... the harmonic distribution is nice too.. so... i cannot present bad numbers or i will loose a huge number of people that will give up to build...not building i have not my payment that is joy to be doing nice things to forum folks and the audiophile communitty.

This have all stuff combined... good feelings... friendly action, Ego be contribute and all human things..all them together.

Of course, any simulator result can be discussed..we can arrange simulator to produce "worst case scenario" too..then numbers will be bad...but this is not decent... i will not manipulate numbers to make them good.


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