Hi, it's my firs post here, but i follow it since 5 months.
I already build a Symasym 5.3 , i designed my own PCB because i upgraded an old Harman Kardon 730 directly with this power amp section (i can post it if someone is interrested to do this upgrade, it work very well).
I'm working in a big power generation plan here and have access to all the equipment required ( PCB software, PCB prototyping milling, Yokogawa FFT recorder ect).
I'm equipped with B&W speakers (603S3, 601S3 and 600S3). They are renowed to be 'revealing' 'transparent' speakers. When my final amp will be finalised, i probably will test it with MagnePlanar speakers and maybe on a famus Sonus Faber pair.
So....
I presently have tested my first version of board (2 sides PCB HK upgrade) and a professionnal version for my final Symasym Amp, the two with the HK small twin supply.The only differrence between the two versions (apart some small PCB diff) is the type of the capacitors in the audio path and i have tested differrent output transistors , the MJW0281/0302 and the Toshibas.
In my opinion the cap (polypropylene vs polyester) don't make a big diff , maybe slitly more flat (non colorised) for the polyprop.
The output transistors (bad test ,one channel vs the other channel) seems to do a big differrence. The Toshibas give a better bass more 'present' but a more colorised or 'round' sound, and the mid cleanless seems to suffer a bit.
Anyway, we have 5 Symasyms in construction here, we are waiting for the 400VA transformers.....more to come.
( excuse me for my bad writing, from a french Canadian...)
Denis
I already build a Symasym 5.3 , i designed my own PCB because i upgraded an old Harman Kardon 730 directly with this power amp section (i can post it if someone is interrested to do this upgrade, it work very well).
I'm working in a big power generation plan here and have access to all the equipment required ( PCB software, PCB prototyping milling, Yokogawa FFT recorder ect).
I'm equipped with B&W speakers (603S3, 601S3 and 600S3). They are renowed to be 'revealing' 'transparent' speakers. When my final amp will be finalised, i probably will test it with MagnePlanar speakers and maybe on a famus Sonus Faber pair.
So....
I presently have tested my first version of board (2 sides PCB HK upgrade) and a professionnal version for my final Symasym Amp, the two with the HK small twin supply.The only differrence between the two versions (apart some small PCB diff) is the type of the capacitors in the audio path and i have tested differrent output transistors , the MJW0281/0302 and the Toshibas.
In my opinion the cap (polypropylene vs polyester) don't make a big diff , maybe slitly more flat (non colorised) for the polyprop.
The output transistors (bad test ,one channel vs the other channel) seems to do a big differrence. The Toshibas give a better bass more 'present' but a more colorised or 'round' sound, and the mid cleanless seems to suffer a bit.
Anyway, we have 5 Symasyms in construction here, we are waiting for the 400VA transformers.....more to come.
( excuse me for my bad writing, from a french Canadian...)
Denis
Does anybody have answers to the questions I posted in the "AAK model builder's" thread?
Mostly it is about differences in resistor values (comparing the "AAK" model to Mike Bittner's original "5.3"):
- base stoppers: R1, R3 AAK: 10R (5.3:1.2R); R8, R9 AAK: 100R (5.3: 22R). In the sequel thread, Mike Bittner said he used 22R for "speed issues", and AAK justified the higher values because they are like in the AKSA and other reputed amps. Is there a definitive answer to this question?
- thermal transistor T1 (BD139): R22 AAK 100R, 5.3: 470R; R23 AAK: 1k, 5.3: 2k; R24 AAK: 316R, 5.3: 499R. I would like to know whether this change has anything to do with the higher rails, or whether it was simply more convenient. I will be using pretty much AAK's BOM but with 36V rails only, so I'd like to know which combo is better for this case, the 5.3 values or the AAK values.
- R26 AAK: 150R "necessary for thermal stability", 5.3: 33R
- output zobel: C18: AAK not in BOM but exists on PCB, 5.3: 47nF; R4: AAK 10R, 5.3: 4R7. I suppose the point is to maintain the same corner frequency, which would put the AAK C18 at 22nF.
- output inductor: AAK none, 5.3: 10R // a dozen windings of 0.6mm dia magnet wire around it. Optional?
- ground link R2 AAK: cannot find R2 on AAK BOM and PCB, 5.3: 10R.
Is IGND and AGND tied or separate on the AAK PCB?
- emitter resistors for the input diff pair if reduced gain desired by increasing R30 to 1k: AAK: not on PCB, 5.3: R16, R19.
This is my original post in the builder's thread, maybe we can keep the parts and building discussion there:
post#10
Mostly it is about differences in resistor values (comparing the "AAK" model to Mike Bittner's original "5.3"):
- base stoppers: R1, R3 AAK: 10R (5.3:1.2R); R8, R9 AAK: 100R (5.3: 22R). In the sequel thread, Mike Bittner said he used 22R for "speed issues", and AAK justified the higher values because they are like in the AKSA and other reputed amps. Is there a definitive answer to this question?
- thermal transistor T1 (BD139): R22 AAK 100R, 5.3: 470R; R23 AAK: 1k, 5.3: 2k; R24 AAK: 316R, 5.3: 499R. I would like to know whether this change has anything to do with the higher rails, or whether it was simply more convenient. I will be using pretty much AAK's BOM but with 36V rails only, so I'd like to know which combo is better for this case, the 5.3 values or the AAK values.
- R26 AAK: 150R "necessary for thermal stability", 5.3: 33R
- output zobel: C18: AAK not in BOM but exists on PCB, 5.3: 47nF; R4: AAK 10R, 5.3: 4R7. I suppose the point is to maintain the same corner frequency, which would put the AAK C18 at 22nF.
- output inductor: AAK none, 5.3: 10R // a dozen windings of 0.6mm dia magnet wire around it. Optional?
- ground link R2 AAK: cannot find R2 on AAK BOM and PCB, 5.3: 10R.
Is IGND and AGND tied or separate on the AAK PCB?
- emitter resistors for the input diff pair if reduced gain desired by increasing R30 to 1k: AAK: not on PCB, 5.3: R16, R19.
This is my original post in the builder's thread, maybe we can keep the parts and building discussion there:
post#10
Hi !!
I'm very very happy with my "classic" symasym 5.3. It have MJL1302 and 3201 output devices, wima mks2 caps with styroflex and mica.
I'm searching for a more powerful version, as my speakers are 8Ohms. I really will be happy with something like 120W @ 8Ohms ! 😀
I found AAK version of Symasym and also Roender version.
What can I expect from these versions?
I want something STABLE and SAFE, just like my classic 5.3. I'm very happy with symasym sound, so it should sound very similar to classic 5.3.
Any tips ?
Best Regards !
I'm very very happy with my "classic" symasym 5.3. It have MJL1302 and 3201 output devices, wima mks2 caps with styroflex and mica.
I'm searching for a more powerful version, as my speakers are 8Ohms. I really will be happy with something like 120W @ 8Ohms ! 😀
I found AAK version of Symasym and also Roender version.
What can I expect from these versions?
I want something STABLE and SAFE, just like my classic 5.3. I'm very happy with symasym sound, so it should sound very similar to classic 5.3.
Any tips ?
Best Regards !
Hi !!
As I already said, I love symasym, and I'm searching for little more power on it.
The original Symasym use MPSA18 transistors, that the maximum suported voltage is 45v. Also use the low voltage BC546.
All other transistors are high voltage rating, the lowest one is the BD139, that is 80v.
So, swapping the MPSA18 with the MPSA42, and the BC546 by the 2n5551 (pins reversed), can I power the Symasym with + - 56v supply rails ?
The idea is swap the low voltage rating transistors with higher ones, and replace the needed resistors, to achieve more power (56v rails), without modify the original symasym design. Is it possible?
Best Regards !
As I already said, I love symasym, and I'm searching for little more power on it.
The original Symasym use MPSA18 transistors, that the maximum suported voltage is 45v. Also use the low voltage BC546.
All other transistors are high voltage rating, the lowest one is the BD139, that is 80v.
So, swapping the MPSA18 with the MPSA42, and the BC546 by the 2n5551 (pins reversed), can I power the Symasym with + - 56v supply rails ?
The idea is swap the low voltage rating transistors with higher ones, and replace the needed resistors, to achieve more power (56v rails), without modify the original symasym design. Is it possible?
Best Regards !
What happened with this topic ? Nobody answers it anymore, I can remember the time that each 5 minutes a new reply was posted !
re. Higher voltage amp
HI,
I have built such a symasym amps like that before, voltage rated +/-56V and another version with 68V. I have change all the transistor to 120V maximum voltage rated. Everything was OK.
Go ahead. Let's have a try. That's OK.
HI,
I have built such a symasym amps like that before, voltage rated +/-56V and another version with 68V. I have change all the transistor to 120V maximum voltage rated. Everything was OK.
Go ahead. Let's have a try. That's OK.
I second that. Even the jump from 36 to 50 V rails is a mere 20log(50/36)=+2.85 dB, same result btw whether expressed as peak SPL, voltage, or power (assuming current and thermal capabilities are scaled accordingly)
"High power" easily sounds impressive unless you express it in dB. 120W gets you just 10log(120/80)=+1.8 dB more than 80W.
Conversely, say if you previously used a 100W amp for a 96dB efficient speaker and now switch to a 84 dB efficent one, you'd now need a 1500W amp (!!!) to get the same SPL.
"High power" easily sounds impressive unless you express it in dB. 120W gets you just 10log(120/80)=+1.8 dB more than 80W.
Conversely, say if you previously used a 100W amp for a 96dB efficient speaker and now switch to a 84 dB efficent one, you'd now need a 1500W amp (!!!) to get the same SPL.
I don't want to have absurd SPL, if I want it I would buy more efficient speakers. I just want to make sure that the amp will NOT clip, avoiding the chance of damage the speakers. The speakers are 88Db/W.
😀
Why I would notice a hard difference? I just want to swap the MPSA18 by the MPSA42 and the BC546 by the 2n5551, the rest will be completely original. I want to power it from 50v rails, not more than that.
Best Regards !
😀
Why I would notice a hard difference? I just want to swap the MPSA18 by the MPSA42 and the BC546 by the 2n5551, the rest will be completely original. I want to power it from 50v rails, not more than that.
Best Regards !
Hi nando,
For +/-50V rails replace the MPSA18 (Q1,Q2) with 2N5551, and keep the BC546 (Q7,Q8). I wouldn't recommend using the MPSA42, hfe is way to low. My symasym works great at +/-50V using these parts. At +/-56V Q7 draws about 250mw which is still 2.5 times lower than BC546 maximum rating. I tried it without any problems.
Al
For +/-50V rails replace the MPSA18 (Q1,Q2) with 2N5551, and keep the BC546 (Q7,Q8). I wouldn't recommend using the MPSA42, hfe is way to low. My symasym works great at +/-50V using these parts. At +/-56V Q7 draws about 250mw which is still 2.5 times lower than BC546 maximum rating. I tried it without any problems.
Al
Hi AAK ! How are you !?
So, I'm supposed to keep te BC546, and swap the MPSA18 by 2N5551, then I can power it with 56v rails ? It shouldn't affect the great symasym sound 😉
So, I'm supposed to keep te BC546, and swap the MPSA18 by 2N5551, then I can power it with 56v rails ? It shouldn't affect the great symasym sound 😉
I think everybody's waiting for AAK's boards to arrive.
When they get here the builder's thread will probably be the one to watch.
When they get here the builder's thread will probably be the one to watch.
Hi nando,
Yes to all your questions. But, I would recommend using +/-50V then 56V. The small gain in power is not worth it.
Al
Yes to all your questions. But, I would recommend using +/-50V then 56V. The small gain in power is not worth it.
Al
Re: re. Higher voltage amp
Without supplementary output pairs?
Very dangerous situation if your speakers go to 4ohm and below!!!
And if you add more output pairs, the VAS is unable to supply current for drivers.
Please keep the original symasym supply with max. 40V and if you want a "Panzer General" reliable amp don't exceed 36V power supply 😀
PhongVuTuan said:
Without supplementary output pairs?
Very dangerous situation if your speakers go to 4ohm and below!!!
And if you add more output pairs, the VAS is unable to supply current for drivers.
Please keep the original symasym supply with max. 40V and if you want a "Panzer General" reliable amp don't exceed 36V power supply 😀
Hi !
So, powering it with 45v would be better, give more headroom than the 36v, and still a "panzer" amp, with 8Ohms speakers of course. What you think? 🙂
Best Regards !
So, powering it with 45v would be better, give more headroom than the 36v, and still a "panzer" amp, with 8Ohms speakers of course. What you think? 🙂
Best Regards !
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