Mike, I want to Bi Amp a System, and I'll use Symasym + LM3886.
In your site, you say that the gain is 32 DB (1:40). So, as LM3886 is a simple Op-Amp, I must place a 40k resistor for feedback and 1K resistor to ground to have the same gain?
Sorry about the newbie question, it's cause I don't know convert DB in gain and vice versa.
Thank you very much !
In your site, you say that the gain is 32 DB (1:40). So, as LM3886 is a simple Op-Amp, I must place a 40k resistor for feedback and 1K resistor to ground to have the same gain?
Sorry about the newbie question, it's cause I don't know convert DB in gain and vice versa.
Thank you very much !
@nando
Very good description of the gainclone. Thats my impression, a shy bass, not much but a little. The little rest I need for satisfaction.
I hope I will hear the SymAsym soon and I can tell you my experience.
Some references for listening:
CD Private Dancer Tina Turner
CD Children of sanches Chuck Manjone
CD Passport Handmade Klaus Doldinger
and many more.
Very good description of the gainclone. Thats my impression, a shy bass, not much but a little. The little rest I need for satisfaction.
I hope I will hear the SymAsym soon and I can tell you my experience.
Some references for listening:
CD Private Dancer Tina Turner
CD Children of sanches Chuck Manjone
CD Passport Handmade Klaus Doldinger
and many more.
Hi,
Do you like maths ?
I hope for you
Common gain formula is :
G = 20 log( Av )
You take it, you shake it and you obtain :
T = 10^(G/20)
And now, with our sweet value :
Av = 10^(32/20)
Av= 10^(1,6)
Av = 39,8
Amplification factor is :
Av = 1 + Rfb / Rg
Take and shake it :
Rfb / Rg = Av - 1 ( we can be lazy and say Av >> 1, but we didn't do it )
Rfb / Rg = 38,8
Take and shake it :
Rfb = 38,8 × Rg
I think we can take Rg = 1 K and Rfb 39 K will be good and cheap.
Boa tarde !
Do you like maths ?
I hope for youCommon gain formula is :
G = 20 log( Av )
You take it, you shake it and you obtain :
T = 10^(G/20)
And now, with our sweet value :
Av = 10^(32/20)
Av= 10^(1,6)
Av = 39,8
Amplification factor is :
Av = 1 + Rfb / Rg
Take and shake it :
Rfb / Rg = Av - 1 ( we can be lazy and say Av >> 1, but we didn't do it )
Rfb / Rg = 38,8
Take and shake it :
Rfb = 38,8 × Rg
I think we can take Rg = 1 K and Rfb 39 K will be good and cheap.
Boa tarde !
Blubbervill, i don't see problems using these Sankens, except maybe the hfe-rating. The sheet only says min 20. Output-BJTs for symasym should have at least ~100. And you might get into mechanical problems with the mt200 case.
Mike
Mike
Hi Mike,
Sankens normally have higher gain, but they may require a higher bias to get into their "happy range".
-Chris 😉
Sankens normally have higher gain, but they may require a higher bias to get into their "happy range".
Now that may be the case (no pun intended).
-Chris 😉
Sanken fits
Mike, thanks for your comment.
I don't know the real hfe of the Sanken. They where selected 4 pairs per channel +/-43V, but I can't remember the parameters. It's to long ago and I have lost my projectfiles. There is only one board left which was used for testing. Driver was MJE 350/340.
The cases of the Sanken fits perfectly when I slide the 15030/15031 some mm to the left and right corner of the board. May I do that?
But thats not the point. I ordered 2 pairs of 3281/1302 for testing.
Thats what DIY is for. Having a lot of fun and get a perfect device.
Maybe nearly perfect.
Günter
Mike, thanks for your comment.
I don't know the real hfe of the Sanken. They where selected 4 pairs per channel +/-43V, but I can't remember the parameters. It's to long ago and I have lost my projectfiles. There is only one board left which was used for testing. Driver was MJE 350/340.
The cases of the Sanken fits perfectly when I slide the 15030/15031 some mm to the left and right corner of the board. May I do that?
But thats not the point. I ordered 2 pairs of 3281/1302 for testing.
Thats what DIY is for. Having a lot of fun and get a perfect device.
Maybe nearly perfect.
Günter
Hi !!!
I ordered a very nice toroid transformer, and I ordered it with 28v supply rails, that would give me 39v. But it came with 31v when idle, so I'll have 43v supply rails. Any problems? Would it work COMPLETELY safe with this voltage?
Best Regards
I ordered a very nice toroid transformer, and I ordered it with 28v supply rails, that would give me 39v. But it came with 31v when idle, so I'll have 43v supply rails. Any problems? Would it work COMPLETELY safe with this voltage?
Best Regards
-_nando-_ said:Hi !!!
I ordered a very nice toroid transformer, and I ordered it with 28v supply rails, that would give me 39v. But it came with 31v when idle, so I'll have 43v supply rails. Any problems? Would it work COMPLETELY safe with this voltage?
Best Regards
I don't remember which input devices you are using. If you are using mpsa18, the answer is NO!
With 65v-BC types or 2n5551 it will work if you use 8ohm speakers.
Mike
Hi,
the opencircuit voltage is allways higher than the loaded voltage.
The 31Vac will give a peak of 43.8Vdc when open circuit. That's 10.7% regulation, a pretty poor toroid if the mains was at rated input voltage. Might the mains have been running higher than nominal transformer rating when you took the measurement?
Subtract 0.7V for one diode and you have 43.1V at the smoothing caps. If you are running the dual rectifier version from dual secondaries subtract 1.4V for the two series diodes in each half supply.
Now bias up the amp and the voltage from the PSU will fall by between 1 and 2V. Expect to have about 41Vdc or so.
Big heatsink to keep the outputs cool!!!
the opencircuit voltage is allways higher than the loaded voltage.
The 31Vac will give a peak of 43.8Vdc when open circuit. That's 10.7% regulation, a pretty poor toroid if the mains was at rated input voltage. Might the mains have been running higher than nominal transformer rating when you took the measurement?
Subtract 0.7V for one diode and you have 43.1V at the smoothing caps. If you are running the dual rectifier version from dual secondaries subtract 1.4V for the two series diodes in each half supply.
Now bias up the amp and the voltage from the PSU will fall by between 1 and 2V. Expect to have about 41Vdc or so.
Big heatsink to keep the outputs cool!!!
The toroid is 115VAC, and at my home I have 128VAC measured. That's why. My output devices are 1302 and 3281.
So, should I replace all MPSA18 with 2N5551? Will this make it completely safe?
Thanksss !!!!
So, should I replace all MPSA18 with 2N5551? Will this make it completely safe?
Thanksss !!!!
I guess ~80w into 8ohms...
If you take care of increased dissipation and replace mpsa18 with 2n5551 it should be safe.
Mike
If you take care of increased dissipation and replace mpsa18 with 2n5551 it should be safe.
Mike
Hi,
Is this from 1pair of output devices per channel?
I could model this for you but I need
smoothing capacitance per rail,
transformer regulation,
maximum operating temperature (during the worst conditions of ambient temperature and partying!).
Is this from 1pair of output devices per channel?
I could model this for you but I need
smoothing capacitance per rail,
transformer regulation,
maximum operating temperature (during the worst conditions of ambient temperature and partying!).
Nando is feeling good, and will be even better listening Symassym
tá curtindo o maior barato!..... boa decisão Nando!
You are enjoying, good decision Nando!
regards,
Carlos
tá curtindo o maior barato!..... boa decisão Nando!
You are enjoying, good decision Nando!
regards,
Carlos
Hi !!
Yes, I like symasym very much (bom pra caralho mesmo !), I already listened it many times, with 33v supply rails. Now it will be even stronger. JBL's were replaced with Beyma loudspeakers that sounds far better and are more sensitive, now with Bi-Amp configuration and a stronger PSU, it will sound HUGE. 😎
To curtindo pra porra esse Symasym - I enjoy symasym very much !
😀
Yes, I like symasym very much (bom pra caralho mesmo !), I already listened it many times, with 33v supply rails. Now it will be even stronger. JBL's were replaced with Beyma loudspeakers that sounds far better and are more sensitive, now with Bi-Amp configuration and a stronger PSU, it will sound HUGE. 😎
To curtindo pra porra esse Symasym - I enjoy symasym very much !
😀
Very good that you have appreciated.
It is very good....no doubts about that.
This object you told..... "bom pra....." is known by the Spanish speaking moderators.
I do not know if they think it is "bom pra" this way..hehe
Melhor manerar amigo... não gostaria de ver empurrarem um tubo no seu orifício!
Best wishes to you....be more and more happy...
You are great... a very nice representative of our happy culture.
regards,
Carlos
It is very good....no doubts about that.
This object you told..... "bom pra....." is known by the Spanish speaking moderators.
I do not know if they think it is "bom pra" this way..hehe
Melhor manerar amigo... não gostaria de ver empurrarem um tubo no seu orifício!
Best wishes to you....be more and more happy...
You are great... a very nice representative of our happy culture.
regards,
Carlos
Hehheheeheh ! How could I imagine that hein Mergulhão !? 
The amplifier is very good indeed !
- I would like to edit the post but it's not allowed anymore
The amplifier is very good indeed !
- I would like to edit the post but it's not allowed anymore