Chris, you're trying to mount your wife's birthday on the heatsink ? 😀 just kidding...
MIA = Missing In Action ?
Please tell me also the negative changes, saves me the time to try them. 😉
Right now i have the feeling that the ccs can be improved. The ccs in symasym is extra picant as it defines the whole amp's operation.
Mike
MIA = Missing In Action ?
Please tell me also the negative changes, saves me the time to try them. 😉
Right now i have the feeling that the ccs can be improved. The ccs in symasym is extra picant as it defines the whole amp's operation.
Mike
Hi Mike,
But first, I have to get the first channel mounted and tested. Dry fit is okay.
-Chris
Misery loves company! 🙄 Oh, allright. As long as you promise to have a good laugh about it.
What else to expect from an electronics guy? Birthday went well, I'm not in the dog house. 🙂
Yes, or MIS (Missing In Shipping).
Let me know what you are up to there. I can incorporate that into a layout change if I know before hand.
But first, I have to get the first channel mounted and tested. Dry fit is okay.
-Chris
Copyright question
Mike >
It can be found legal notice on symasym website http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html :
"Authorized for use by any private hobbyist, commercial use / profit unauthorized !"
I wonder if you do allow situation, that DIYer (not me), will use schematics and PCB to produce for ex. 5 symasyms for sale?
You know: group order - few parts and PCB left...
Why not to solder it...?
What's your opinion?
greetings form Poland
kubedes
Mike >
It can be found legal notice on symasym website http://www.lf-pro.net/mbittner/Sym5_Webpage/symasym5_3.html :
"Authorized for use by any private hobbyist, commercial use / profit unauthorized !"
I wonder if you do allow situation, that DIYer (not me), will use schematics and PCB to produce for ex. 5 symasyms for sale?
You know: group order - few parts and PCB left...
Why not to solder it...?
What's your opinion?
greetings form Poland
kubedes
Hi Mike,
The first Symasym came alive in the most boring manner. No smoke, no excessive current, no oscillation. DC offset was +3.5 mV. Too early to form an opinion yet. Sounded much as I expected, and that's not a bad thing. I tried 70 mA bias to start.
-Chris
The first Symasym came alive in the most boring manner. No smoke, no excessive current, no oscillation. DC offset was +3.5 mV. Too early to form an opinion yet. Sounded much as I expected, and that's not a bad thing. I tried 70 mA bias to start.
-Chris
Hi Mike,
I lied. DC offset is actually -1.5 mV at the proper bipolar 34 V supply voltage. It drifted down to -2 mV warmed up. I'll have to build the other channel to let you know how it sounds in relation to some other stuff.
Promising amp.
-Chris
I lied. DC offset is actually -1.5 mV at the proper bipolar 34 V supply voltage. It drifted down to -2 mV warmed up. I'll have to build the other channel to let you know how it sounds in relation to some other stuff.
Promising amp.
-Chris
Great news
Hello folks,
It is nice to see that more people are finishing their amps.
It was few weeks ago, I asked here where to get MJL0281/0302 transistors.
Well, I finally got those. I ordered samples of those in the spring and my order was soon after that canceled.
Yesterday I got a call from UPS that there is a package for me from Onsemi.
It contained the ordered parts 🙂 Now I can finally begin with the parts I originally wanted.
Jarno
Hello folks,
It is nice to see that more people are finishing their amps.
It was few weeks ago, I asked here where to get MJL0281/0302 transistors.
Well, I finally got those. I ordered samples of those in the spring and my order was soon after that canceled.
Yesterday I got a call from UPS that there is a package for me from Onsemi.
It contained the ordered parts 🙂 Now I can finally begin with the parts I originally wanted.
Jarno
Chris, next time i will integrate a small smoke bomb... 😀
About the DC-offset, immediately after power up it should read <1mv and drift to ~-3mv. I guess your thermal coupling reduced that to 2mv.
Nice to see that it works fine from the beginning !
Hi kubedes, i have no problems with group buys, as long as the resulting profit is not much more than a few beers.
I have followed borys' work, and as he has much work with it, he earned some beers.
Jarno, that's good news ! So OnSemi continued making MJL0281/0302 ?
Mike
About the DC-offset, immediately after power up it should read <1mv and drift to ~-3mv. I guess your thermal coupling reduced that to 2mv.
Nice to see that it works fine from the beginning !
Hi kubedes, i have no problems with group buys, as long as the resulting profit is not much more than a few beers.
I have followed borys' work, and as he has much work with it, he earned some beers.
Jarno, that's good news ! So OnSemi continued making MJL0281/0302 ?
Mike
Mike>
Thank you for your answer.
I din't mean borys. 🙄
Let us just act "fair play". 🙂
Back to topic.
I will solder symasym in next few days.
i'm still waiting for PCB that borys is ordering. 😉 rest of parts is wainting.
What abot matching transistors?
"Multimeter matching" is enough?
Maybe you have setup/schema to recommend?
kubedes
Thank you for your answer.
I din't mean borys. 🙄
Let us just act "fair play". 🙂
Back to topic.
I will solder symasym in next few days.
i'm still waiting for PCB that borys is ordering. 😉 rest of parts is wainting.
What abot matching transistors?
"Multimeter matching" is enough?
Maybe you have setup/schema to recommend?
kubedes
Hello folks,
First of all, I want to thank you all for your hard work, especially Michael, Pavel and Carlos.
I have few question related with component selection. First; I have two type of drivers MJE15030/31 and MJE15034/35 and as a finals MJL4281a/4302a. Should I use 15034/35, as ONsemi recommend as drivers for my finals, or should I use the designed drivers transistors for symasym?
Second; I don't find cap's, other than ceramics NP0/C0G type, for 10pF and 330pF. The 100pf, I have half styroflex and falf silver-mica. I have many 68pF styroflex, it can be used as C5?
It will "sound" good with all that setup? 🙂
Thank You,
Mihai
First of all, I want to thank you all for your hard work, especially Michael, Pavel and Carlos.
I have few question related with component selection. First; I have two type of drivers MJE15030/31 and MJE15034/35 and as a finals MJL4281a/4302a. Should I use 15034/35, as ONsemi recommend as drivers for my finals, or should I use the designed drivers transistors for symasym?
Second; I don't find cap's, other than ceramics NP0/C0G type, for 10pF and 330pF. The 100pf, I have half styroflex and falf silver-mica. I have many 68pF styroflex, it can be used as C5?
It will "sound" good with all that setup? 🙂
Thank You,
Mihai
Hi Mike,
My work has only begun. Firing it up this morning the offset started close to -1 mV and drifts to -3.0 mV. Anything below 10 mV is great, below 50 mV I'll accept depending on the schematic. I think the annoying stuff I hear are those ceramic caps. They will be changed out once I fully test this one.
Hi Clem,
Yes, your boards work great! Thank you very much for those Clem! I need to make more of these for experiments and my own use. Those On-Semi parts are true winners. I sincerely hope they continue to produce them..
-Chris
It would ensure that people report the truth! 😀
My work has only begun. Firing it up this morning the offset started close to -1 mV and drifts to -3.0 mV. Anything below 10 mV is great, below 50 mV I'll accept depending on the schematic. I think the annoying stuff I hear are those ceramic caps. They will be changed out once I fully test this one.
Hi Clem,
Yes, your boards work great! Thank you very much for those Clem! I need to make more of these for experiments and my own use. Those On-Semi parts are true winners. I sincerely hope they continue to produce them..
-Chris
kubedes said:
Kubedes, i'm sorry if i sounded different than i meant...
If your multimeter is of high quality, it should do the job.
See my webpage:
" Matching is simple, no complementary matching is required. Following pairs need matching: Q1<->Q2, Q3<->Q9, Q4<->Q12
With good matching DC-offset is easily below 3mv. Matching outputdevices is optional, i didn't."
Mike
roender said:
Mihai, c5 is supposed to be 100nF. For a start the NPOs should be fine, but you really should try getting better caps for C3/4/14/2.
The MJE15034/35 has often been used, they should be fine. It will not sound "bad" with the ceramics, but better caps (especially c14) is easily audible.
Chris, what is the annoying stuff you hear ? Can you describe ?
Mike
Hi Mike,
Instead of a clear "ting", there is some "shing" mixed in. Female vocals sound a little dirty in the high registers. I am listening to Loreena McKennitt. Harps and acoustic with femal vocal. Celtic (The Visit).
Keep in mind that this is only my impression. I have been able to eliminate this sound in other amp designs (some). Also remember that those darn ceramics are in there. Even the dreaded C14. I expected it to sound something like this with those components, but I wanted to do some testing before replacing them.
I will let you know how things sound when you amp is built properly. 😉
I don't notice any problems in the bass response with the 1 uF coupling cap.
-Chris
Instead of a clear "ting", there is some "shing" mixed in. Female vocals sound a little dirty in the high registers. I am listening to Loreena McKennitt. Harps and acoustic with femal vocal. Celtic (The Visit).
Keep in mind that this is only my impression. I have been able to eliminate this sound in other amp designs (some). Also remember that those darn ceramics are in there. Even the dreaded C14. I expected it to sound something like this with those components, but I wanted to do some testing before replacing them.
I will let you know how things sound when you amp is built properly. 😉
I don't notice any problems in the bass response with the 1 uF coupling cap.
-Chris
MikeB said:
Ok.
It is high quality. Thanks.
MikeB said:
I know that site very good.
Just needed info how to match.
Maybe my symasym will be ready 'till eNd of the sertember. I hope so !!
Dual mono. 2 Toroids 2x25V \ 300VA. Double bridge on HEXFRED .
44mF/50V Spraque elyts each channel. 😀
greetings
kubedes
Mihai, c7 is part of feedback compensation and must not be reduced. But for c7 a ceramic is ok. (high voltage bias)
Chris, yes, it's possible that this is caused by the ceramics, i guess we'll find out when you have replaced the ceramics with the micas.
It's also possible that there is somewhere a resonance, in this case adding ~33ohm re's to the input ltp would stop that.
In my experience symasym does a "perfect" job with female vocals.
Kubedes, match the bjts for hfe, especially the input <1%. My experience is, that matched hfe automatically gives matched vbe.
Mike
Chris, yes, it's possible that this is caused by the ceramics, i guess we'll find out when you have replaced the ceramics with the micas.
It's also possible that there is somewhere a resonance, in this case adding ~33ohm re's to the input ltp would stop that.
In my experience symasym does a "perfect" job with female vocals.
Kubedes, match the bjts for hfe, especially the input <1%. My experience is, that matched hfe automatically gives matched vbe.
Mike
Hi Mike,
Here is some testing with standard test instruments. The measured THD was 0.017%. The Leader LAG-120B I'm using measures 0.032%, the lower impedance of the Symasym swamps out the hum pickup I guess. I am seeing 60Hz noise on the generator residuals.
So, 1 KHz at 10 Vrms into an 8 ohm, non-inductive dummy load at a bias current of 60 mA ........
The bottom trace is the residual from the THD meter (Leader LDM-171)
-Chris
Here is some testing with standard test instruments. The measured THD was 0.017%. The Leader LAG-120B I'm using measures 0.032%, the lower impedance of the Symasym swamps out the hum pickup I guess. I am seeing 60Hz noise on the generator residuals.
So, 1 KHz at 10 Vrms into an 8 ohm, non-inductive dummy load at a bias current of 60 mA ........
The bottom trace is the residual from the THD meter (Leader LDM-171)
-Chris
