Hi,sx-Amp and nx-Amp
Updated January 15 2016
I've put the complete Gerbers and drill files for the nx-Amplifier and sx-Amplifier up on my website hifisonix.com
If you want to make 'em, everything is there - look under the respective amplifier posts.
I was not able to find the gerber on the website?
Can anyone explain were they are😕?
Ampi, The Gerbers are not there - I took them down . Please take the link to Jim's audio to buy a set of boards - ~$25-00 for two amplifer boards and a PSU board - DSTHP with silk screen and gold flashed.
I will update the post to remove that info.
I will update the post to remove that info.
I have updated the sx-Amplifier doc to reflect the findings of various builders. It should be correct now. There is a link to the doc in the first post of this thread.
Hi Bonsai
Please help clarify the below, am confused on what should be the value of R6, between which two points of R6 this should be measured ??
You responded to my previous query as :
2. R20 should be 2.2k 0.5W - YES. ADJUST R6 FOR MAXIMUM AND NOT MINIMUM AS IT STATES IN THE BUILD DOCUMENT
Where as in doc ver 2.10 it was mentioned as
" Measure across R6 (the output stage quiescent current set resistor) and adjust for its minimum value – i.e. 0 Ohms. This is important! "
Which one is correct ? and any easy way of achieving this without ambiguity for noobs like me? eg., adjust R6 so that resistance between pin x and y of trimmer R6 should be xxxx
Thanks for your support.
Please help clarify the below, am confused on what should be the value of R6, between which two points of R6 this should be measured ??
You responded to my previous query as :
2. R20 should be 2.2k 0.5W - YES. ADJUST R6 FOR MAXIMUM AND NOT MINIMUM AS IT STATES IN THE BUILD DOCUMENT
Where as in doc ver 2.10 it was mentioned as
" Measure across R6 (the output stage quiescent current set resistor) and adjust for its minimum value – i.e. 0 Ohms. This is important! "
Which one is correct ? and any easy way of achieving this without ambiguity for noobs like me? eg., adjust R6 so that resistance between pin x and y of trimmer R6 should be xxxx
Thanks for your support.
Hi Bonsai, the SX build pdf appears to be missing from your web site, or am I just being daft? I have viewed it before but can't find it now.
Thanks
Alan
Thanks
Alan
Oh - sorry about that. I posted the updated copy under the sx-Amp amp stuff. I'll get back to you shortly.
alibear and others that have tried to download the sx-Amplifier pdf - the link on my website is now fixed.
Here is a direct link: The-sx-Amplifier-V2.10
😎
Here is a direct link: The-sx-Amplifier-V2.10
😎
Thank you Bonsai pdf available again, much appreciated.
About to embark on constructing of SX. PCB appears to be very good quality, components on order.
Alan
About to embark on constructing of SX. PCB appears to be very good quality, components on order.
Alan
Query on R4 - SX board V1.0
Hi Bonsai,
I am almost done with populating boards... final checks..
My SX boards version is 1.0 and as per document 2.10 R4 should not be populated, I hv put 15ohm and shorted J2. Do I need to take out R4 ??
Another question, while adjusting the R6/R1 for one module, do the other module also to be connected to psu board or I can do one board after other ?
https://goo.gl/photos/hPLfmSkR7Ues8UpF9
Thanks
Hi Bonsai,
I am almost done with populating boards... final checks..
My SX boards version is 1.0 and as per document 2.10 R4 should not be populated, I hv put 15ohm and shorted J2. Do I need to take out R4 ??
Another question, while adjusting the R6/R1 for one module, do the other module also to be connected to psu board or I can do one board after other ?
https://goo.gl/photos/hPLfmSkR7Ues8UpF9
Thanks
Balu,
You must take out R4 in Version 1 boards - do not fit it.
For R6 adjustment you can do it one after the other.
Regards
Andrew
You must take out R4 in Version 1 boards - do not fit it.
For R6 adjustment you can do it one after the other.
Regards
Andrew
Can someone confirm my understanding of the sx-amp speaker and gnd wiring?? Many thanks
https://goo.gl/photos/5EDVmkiwuf3EoTwTA
https://goo.gl/photos/5EDVmkiwuf3EoTwTA
Balu,
you must swap the two SIG GND connections with the 0V connections.
The SIG 0V is the main 0V for the Amp board. The 0V connections are where the speaker return connections must come to.
All the other connections are correct in your diagram.
Also, note carefully the following:-
Twist tightly together the connections from the transformer secondary's between the transformer and the PSU board
If your connection between the amplifier output and the speaker terminals is more than say 6 inches (150mm), then twist the speaker + and the speaker - together inside your chassis.
Keep the connections between the input on the amplifier board and the input RCA sockets SHORT as possible and keep them away from any speaker or mains wires.
Finally, make sure the RCA sockets GND does NOT touch the metal chassis. The GND from the RCA input socket must go directly to the input GND on the amplifier board.
you must swap the two SIG GND connections with the 0V connections.
The SIG 0V is the main 0V for the Amp board. The 0V connections are where the speaker return connections must come to.
All the other connections are correct in your diagram.
Also, note carefully the following:-
Twist tightly together the connections from the transformer secondary's between the transformer and the PSU board
If your connection between the amplifier output and the speaker terminals is more than say 6 inches (150mm), then twist the speaker + and the speaker - together inside your chassis.
Keep the connections between the input on the amplifier board and the input RCA sockets SHORT as possible and keep them away from any speaker or mains wires.
Finally, make sure the RCA sockets GND does NOT touch the metal chassis. The GND from the RCA input socket must go directly to the input GND on the amplifier board.
Hi Bonsai
I have started testing the modules and could not configure the current to 1.4A
Adjusting R6 could not go below 2.05A 1st board and 1.96A on 2nd board.
between 0v and Amp out i could adjust to 0.00mv on board boards after adding another 10k parallel to R1 (to make it ~5k). The variance over an hour is between 8mv to -9mv.
I have added another 2.2k in series to R21 and got the current adjusted approx 1.6 amp on both boards (not sure this is right approach) could not do below this.
Q3 is BC547C.
Am using 0-18 x 2, 7Amp (approx 252va) transformer with the PSU and getting +/- 25.2V as dc output.
Board 1 - details
Q8, Q9 are bc547c and Q10, Q11 are bc557c and hfe are bc547c (627, 628), bv557c (656, 661), no vbe matching done (i dont know how to do it)
J2 shorted, R4 removed (as advised)
voltage values across Zenors are 9.92v and 9.92v
Across R37 (150ohm) = 138mv
Across R36 (150ohm) = 138mv
Across R33 (1k) = 1.196V
Across (R32 (1K) = 1.16v
Across R30 (15ohm) = 495mv
Across R31 (15ohm) = 535mv
Across R29 (100ohm) = 138mv
Across R28 (100ohm) = 131mv
Across R24 (0.33R) and R25 (0.33R) = 525mv
Across R25 (0.33R) = 326mv
Across R27 (0.33R) = 212mv
Across R24 (0.33R) = 196mv
Across R26 (0.33R) = 348mv
Q2 = NJW3281
Q1 = NJW1302
Q4 = NJW1302
Q5 = NJW3281
Q6=2SA1360
Q7=2SA3423
All parts are bought from mouser, rscomponents, element14.
Amp is singing and not sure it is at its best...
Please review the above and suggest whats could be wrong with this to debug further to adjust the current to appropriate level.
Thanks,
I have started testing the modules and could not configure the current to 1.4A
Adjusting R6 could not go below 2.05A 1st board and 1.96A on 2nd board.
between 0v and Amp out i could adjust to 0.00mv on board boards after adding another 10k parallel to R1 (to make it ~5k). The variance over an hour is between 8mv to -9mv.
I have added another 2.2k in series to R21 and got the current adjusted approx 1.6 amp on both boards (not sure this is right approach) could not do below this.
Q3 is BC547C.
Am using 0-18 x 2, 7Amp (approx 252va) transformer with the PSU and getting +/- 25.2V as dc output.
Board 1 - details
Q8, Q9 are bc547c and Q10, Q11 are bc557c and hfe are bc547c (627, 628), bv557c (656, 661), no vbe matching done (i dont know how to do it)
J2 shorted, R4 removed (as advised)
voltage values across Zenors are 9.92v and 9.92v
Across R37 (150ohm) = 138mv
Across R36 (150ohm) = 138mv
Across R33 (1k) = 1.196V
Across (R32 (1K) = 1.16v
Across R30 (15ohm) = 495mv
Across R31 (15ohm) = 535mv
Across R29 (100ohm) = 138mv
Across R28 (100ohm) = 131mv
Across R24 (0.33R) and R25 (0.33R) = 525mv
Across R25 (0.33R) = 326mv
Across R27 (0.33R) = 212mv
Across R24 (0.33R) = 196mv
Across R26 (0.33R) = 348mv
Q2 = NJW3281
Q1 = NJW1302
Q4 = NJW1302
Q5 = NJW3281
Q6=2SA1360
Q7=2SA3423
All parts are bought from mouser, rscomponents, element14.
Amp is singing and not sure it is at its best...
Please review the above and suggest whats could be wrong with this to debug further to adjust the current to appropriate level.
Thanks,
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Board 2 - details
R6 adjusted to achieve 1.7A its not going below this.
Q8, Q9 are bc547c and Q10, Q11 are bc557c and hfe are bc547c (641, 643), bv557c (652, 655), no vbe matching done (i dont know how to do it)
J2 shorted, R4 removed (as advised)
voltage values across Zenors are 9.89v and 9.88v
Across R37 (150ohm) = 137mv
Across R36 (150ohm) = 138mv
Across R33 (1k) = 1.18V
Across (R32 (1K) = 1.17v
Across R30 (15ohm) = 480mv
Across R31 (15ohm) = 533mv
Across R29 (100ohm) = 137mv
Across R28 (100ohm) = 130mv
Across R24 (0.33R) and R25 (0.33R) = 429mv
Across R25 (0.33R) = 245mv
Across R27 (0.33R) = 233mv
Across R24 (0.33R) = 175mv
Across R26 (0.33R) = 301mv
Q2 = NJW3281
Q1 = NJW1302
Q4 = NJW1302
Q5 = NJW3281
Q6=2SA1360
Q7=2SA3423
R6 adjusted to achieve 1.7A its not going below this.
Q8, Q9 are bc547c and Q10, Q11 are bc557c and hfe are bc547c (641, 643), bv557c (652, 655), no vbe matching done (i dont know how to do it)
J2 shorted, R4 removed (as advised)
voltage values across Zenors are 9.89v and 9.88v
Across R37 (150ohm) = 137mv
Across R36 (150ohm) = 138mv
Across R33 (1k) = 1.18V
Across (R32 (1K) = 1.17v
Across R30 (15ohm) = 480mv
Across R31 (15ohm) = 533mv
Across R29 (100ohm) = 137mv
Across R28 (100ohm) = 130mv
Across R24 (0.33R) and R25 (0.33R) = 429mv
Across R25 (0.33R) = 245mv
Across R27 (0.33R) = 233mv
Across R24 (0.33R) = 175mv
Across R26 (0.33R) = 301mv
Q2 = NJW3281
Q1 = NJW1302
Q4 = NJW1302
Q5 = NJW3281
Q6=2SA1360
Q7=2SA3423
The bias voltage across the multiplier is not stated.
This is also the voltage between the bases of the driver stage.
Expect ~2.4V to account for the 4 Vbe drops of the drivers+outputs+Vre
You can also measure the voltage between the bases of the output devices. Expect ~1.2V
You can change the multiplier ratio by changing the resistor ladder.
A higher BE resistance gives a lower bias voltage
A lower BE resistance gives a higher bias voltage and a higher output bias current.
Maybe your BE resistors are too low?
This is also the voltage between the bases of the driver stage.
Expect ~2.4V to account for the 4 Vbe drops of the drivers+outputs+Vre
You can also measure the voltage between the bases of the output devices. Expect ~1.2V
You can change the multiplier ratio by changing the resistor ladder.
A higher BE resistance gives a lower bias voltage
A lower BE resistance gives a higher bias voltage and a higher output bias current.
Maybe your BE resistors are too low?
@AnudrewT - Not very clear how to measure these and where to measure...
For some reason on both boards i could not adjust current to 1.4A.
When I power up with R20 2.2K and r21 1k, r6 1k pot. The starting current is about 2.2A and adjusting R6 i could go minimum to 1.8A
When I up R20 to 4.7k and r21 1k, r6 1kpot, the starting current is about 1.6A.
it was never around 300-400ma as suggested in document .. not sure which component is causing this mess up.
I have tested both boards with R21 1K, R20 1K and r6 1k pot also. In this situation the starting current above 2.4-2.5A and its blowing the fuse kept across NEG power connection.i.e.,J5 fuse blowing...
Q3 is BC547C and I checked the orientation, its correctly mounted, R6 is functioning as adjusting it inreasing the current even further 🙁 , measured R21 its a dale 1k and is indeed showing 1k when measured by taking out of board.
When measured between BC547 B,E the resistance coming to 2.2k or whatever i kept at R20 (currently kept 4.4k)
Any thoughts/suggestions
For some reason on both boards i could not adjust current to 1.4A.
When I power up with R20 2.2K and r21 1k, r6 1k pot. The starting current is about 2.2A and adjusting R6 i could go minimum to 1.8A
When I up R20 to 4.7k and r21 1k, r6 1kpot, the starting current is about 1.6A.
it was never around 300-400ma as suggested in document .. not sure which component is causing this mess up.
I have tested both boards with R21 1K, R20 1K and r6 1k pot also. In this situation the starting current above 2.4-2.5A and its blowing the fuse kept across NEG power connection.i.e.,J5 fuse blowing...
Q3 is BC547C and I checked the orientation, its correctly mounted, R6 is functioning as adjusting it inreasing the current even further 🙁 , measured R21 its a dale 1k and is indeed showing 1k when measured by taking out of board.
When measured between BC547 B,E the resistance coming to 2.2k or whatever i kept at R20 (currently kept 4.4k)
Any thoughts/suggestions
Balu,
Across R24 (0.33R) and R25 (0.33R) = 525mv
This is 795mA per pair = 1.6A in the output stage excluding current required for the fron't end (another ~100-150mA). You should be able to adjust it down, so it seems you are at the top end of the adjustment range.
Can you take out R20 completely - the current should drop to 0 or a few mA.
But, before you do that, can you measure the voltage at the output wrt ground - it should be just a few mV.
Also, make sure your Zobel is connected correctly. *I once had the speaker output and the Zobel swapped.
Across R24 (0.33R) and R25 (0.33R) = 525mv
This is 795mA per pair = 1.6A in the output stage excluding current required for the fron't end (another ~100-150mA). You should be able to adjust it down, so it seems you are at the top end of the adjustment range.
Can you take out R20 completely - the current should drop to 0 or a few mA.
But, before you do that, can you measure the voltage at the output wrt ground - it should be just a few mV.
Also, make sure your Zobel is connected correctly. *I once had the speaker output and the Zobel swapped.
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