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Hi Mauro,
thank you very much for your schematics.
I only have some questions cencerning the setup you recommend for your approach:
Are you using your approach with a preamp? If yes which preamp? Is it advisable to use your approach with a potentiometer as a integrated amplifier?
Thanks
Floric
Hi Mauro,
thank you very much for your schematics.
I only have some questions cencerning the setup you recommend for your approach:
Are you using your approach with a preamp? If yes which preamp? Is it advisable to use your approach with a potentiometer as a integrated amplifier?
Thanks
Floric
I use this amplifier with launch preamplifiers, because me understanded of often change my setup. Sincerely, am appraising the idea to build from it a High- end and per hour from it uses a provisional based on LM318 modified ( low open loop gain & large BW ).
The imput impedance of this amplifier is 100Kohm and the gain is 30 dB, for which not there are particular problems of interface with a log pot.. Suggestion to use a value not superior to 22Kohm, to avoid that the serious resistance creates an excessive high frequency cut off.
Ciao
Mauro
The imput impedance of this amplifier is 100Kohm and the gain is 30 dB, for which not there are particular problems of interface with a log pot.. Suggestion to use a value not superior to 22Kohm, to avoid that the serious resistance creates an excessive high frequency cut off.
Ciao
Mauro
Any technical precise statements:
In the circuit I have not specified the method of protection for the
breakdowns. How to have noticed, am not add Fuse there on +-35V. To protect from possible breakdowns, have anticipateded to use a delayed fuse of the same value of the current max. of the transformer ( es. 300VA at230V=1.3A or 300VA at 120V = 2.5A )
A detail that I have not explained is that have chosen deliberately to not using the fuses on the card, because they increase the Zout of the PSU and overall much times are source of not linearity in the peak current, on account of the contacts with the socket and of the termal cicles (D. Self have investigate this problem on power output, but it's teorical analog on PSU).
If is wants insert the fuses are able insert to mountain of the diode bridge or of the electrolytic capacitors ( holding account of their current charge peak ).
In any case LM3886 and the bridge that I have make a will am practically indestructible, and the loudspeakers are well protected.
LM318N has to be of National Semicnoductor production. Other manufactures have not was characteristic( believe for tolerances of testing or little differences in the net of compensation ) and have not same audio quality. If you wants fun with the theories of OPamp linearizing, you are able put a resistance from 470Kohm among the pin 6 and 8. This modifies reduce the opened loop gain to about 65dB, and widens the BW to over 20Khz. This modifies me like much in my preamplifier. To try...
Ciao
Mauro
In the circuit I have not specified the method of protection for the
breakdowns. How to have noticed, am not add Fuse there on +-35V. To protect from possible breakdowns, have anticipateded to use a delayed fuse of the same value of the current max. of the transformer ( es. 300VA at230V=1.3A or 300VA at 120V = 2.5A )
A detail that I have not explained is that have chosen deliberately to not using the fuses on the card, because they increase the Zout of the PSU and overall much times are source of not linearity in the peak current, on account of the contacts with the socket and of the termal cicles (D. Self have investigate this problem on power output, but it's teorical analog on PSU).
If is wants insert the fuses are able insert to mountain of the diode bridge or of the electrolytic capacitors ( holding account of their current charge peak ).
In any case LM3886 and the bridge that I have make a will am practically indestructible, and the loudspeakers are well protected.
LM318N has to be of National Semicnoductor production. Other manufactures have not was characteristic( believe for tolerances of testing or little differences in the net of compensation ) and have not same audio quality. If you wants fun with the theories of OPamp linearizing, you are able put a resistance from 470Kohm among the pin 6 and 8. This modifies reduce the opened loop gain to about 65dB, and widens the BW to over 20Khz. This modifies me like much in my preamplifier. To try...
Ciao
Mauro
Have not well understanded to do it reports you. From your allusion to the LM3886, believe that you has of the doubts on the operation of the varying the latests that have proposeded.
I don't know as I am accustomed to working other participants of this forum, but of some I make a will always in the every reality circuit that develop. Not only, but I propose the layout PCB that I have used to avoid problems in this sense (oscillations,etc...).
Naturally the configuration to bridge of LM3886 makes it intrinsec more unstable, but the only limit of this topology (in my app.) is a clipping more "nervous". Defines the "dangerous" thing for this seem me exaggerator.
Is not the first that is set the problem of "establishes" if this circuit works or no. This circuit is not a variation of datasheet, is not a GC or a his variation, is not a casual nest of 2 OPamp. What likes or no, it is a my personal interpretation about how improving the "musical" performances of an amplifier, without using expensive or time-wasting technology. All have the legal right to appraise the validity of my proposal, and to decide if try it or no. Different is to questions my technical ability ( I with the electronic planning work, not fun).
Ciao
Mauro
I don't know as I am accustomed to working other participants of this forum, but of some I make a will always in the every reality circuit that develop. Not only, but I propose the layout PCB that I have used to avoid problems in this sense (oscillations,etc...).
Naturally the configuration to bridge of LM3886 makes it intrinsec more unstable, but the only limit of this topology (in my app.) is a clipping more "nervous". Defines the "dangerous" thing for this seem me exaggerator.
Is not the first that is set the problem of "establishes" if this circuit works or no. This circuit is not a variation of datasheet, is not a GC or a his variation, is not a casual nest of 2 OPamp. What likes or no, it is a my personal interpretation about how improving the "musical" performances of an amplifier, without using expensive or time-wasting technology. All have the legal right to appraise the validity of my proposal, and to decide if try it or no. Different is to questions my technical ability ( I with the electronic planning work, not fun).
Ciao
Mauro
I have seen that some members is building this circuit. In this post I reassume the My_REf evolution, and the possible variations.
In this circuit I have sought-aftered nearly exclusively any "sonic" characteristics that like it. In particular, I am not worried me to improve the behaviour to the clipping and the "extreme" stabilities ( es: pure capacitive load ), because my is an applicatory example, not a commercial circuit to all the effects.
Naturally this circuit is perfectly working in all the his variations, and I have make a will to found all the conditions. Base on the tastes of every DIY, is possible to modify the encircled for changes the "sonic" imprint.
Every change described in this post does reference to the final scheme of My_ref understanded in the kit complete of PCB Layout.
- Basic version = My_ref BOM; "Old style" sound. Good for ZLoad>=8ohm or "fizzy" speakers.
- Variant 1 = replace C10(100p) & C25(100p) to 47pF(MKT or C0G); like basic version but for load< 8ohm
- Variant 2 = add net C30+R37 & C31+R38, add C32 & C33, change C10 &C25 value. see schematic... ; improved stability, reduce load dependent, ecc... This is a best (actual) tech/sound compromise. try it you...
- Variant 3 = Bridge value = old My_amp (first schematic). It is sufficient replace R5-6-8-9 & R28-28-31-32 to 10K 0.1% and R3-26 to 0.01 2W. It is a "ibrid" solutions among variant 1 and variant 2.
- for all variant: Add R39(470K) & R40(470k) for improved input stage linearity (OL BW=20Khz & OL gain=65dB). Not in all the conditions it improves the final sound, try it you...
My actualy circuit on evaluations is variant 2, but I elaborate ( and make a will ) a variation per week....
Ciao
Mauro
In this circuit I have sought-aftered nearly exclusively any "sonic" characteristics that like it. In particular, I am not worried me to improve the behaviour to the clipping and the "extreme" stabilities ( es: pure capacitive load ), because my is an applicatory example, not a commercial circuit to all the effects.
Naturally this circuit is perfectly working in all the his variations, and I have make a will to found all the conditions. Base on the tastes of every DIY, is possible to modify the encircled for changes the "sonic" imprint.
Every change described in this post does reference to the final scheme of My_ref understanded in the kit complete of PCB Layout.
- Basic version = My_ref BOM; "Old style" sound. Good for ZLoad>=8ohm or "fizzy" speakers.
- Variant 1 = replace C10(100p) & C25(100p) to 47pF(MKT or C0G); like basic version but for load< 8ohm
- Variant 2 = add net C30+R37 & C31+R38, add C32 & C33, change C10 &C25 value. see schematic... ; improved stability, reduce load dependent, ecc... This is a best (actual) tech/sound compromise. try it you...
- Variant 3 = Bridge value = old My_amp (first schematic). It is sufficient replace R5-6-8-9 & R28-28-31-32 to 10K 0.1% and R3-26 to 0.01 2W. It is a "ibrid" solutions among variant 1 and variant 2.
- for all variant: Add R39(470K) & R40(470k) for improved input stage linearity (OL BW=20Khz & OL gain=65dB). Not in all the conditions it improves the final sound, try it you...
My actualy circuit on evaluations is variant 2, but I elaborate ( and make a will ) a variation per week....
Ciao
Mauro
Thanks Mauro!
A few questions:
1) I notice that in this new schematic you have a 470K resistor(R39/R40) from U1 out(pin 6) to U1 comp -2(pin 8) Is this resistor critical? Can it be ommited? Since there are no pads for R39/R40 on the rev. 1 boards, I suppose one could simply solder a small (1/8 - 1/4W) resistor directly to the op amp, or on the bottom of the board.
2) I think I found an error on the silk screen/serigraphy on your first revision. R9 does not match the schematic, and R50 is missing altogether. I am referring to REV E. (17/12/2003). Is there a more up to date schmatic? I just want to be sure the schematic I have matches the boards I just had made.
3) Also, where would one put C30/31 and R37/38 on the Rev. 1 boards.
Thanks,
Russ
A few questions:
1) I notice that in this new schematic you have a 470K resistor(R39/R40) from U1 out(pin 6) to U1 comp -2(pin 8) Is this resistor critical? Can it be ommited? Since there are no pads for R39/R40 on the rev. 1 boards, I suppose one could simply solder a small (1/8 - 1/4W) resistor directly to the op amp, or on the bottom of the board.
2) I think I found an error on the silk screen/serigraphy on your first revision. R9 does not match the schematic, and R50 is missing altogether. I am referring to REV E. (17/12/2003). Is there a more up to date schmatic? I just want to be sure the schematic I have matches the boards I just had made.
3) Also, where would one put C30/31 and R37/38 on the Rev. 1 boards.
Thanks,
Russ
Specifically the serigraphy in post #59 does not seem to me to match the schematic on post #58. Could you please clarify this for me. I am a little confused.
Would it be possible for you to send a zip file with the schematic/serigraphy/BOM/copper for the boards I have had made from the gerbers you sent me. I just want to be sure those of us building that amp are working from the correct design.
Please pardon me if I am missing something obvious.
Sincerely,
Russ
Would it be possible for you to send a zip file with the schematic/serigraphy/BOM/copper for the boards I have had made from the gerbers you sent me. I just want to be sure those of us building that amp are working from the correct design.
Please pardon me if I am missing something obvious.
Sincerely,
Russ
I knew that my updatings were able create a "nervousness", but doesn't worry , now do;
1. The variations that propose are not obligatory and suggestion to try it with calm, after has built the first original circuit version.
2. order all the added of version 2 presents in the scheme My_ref_version2.pdf it is not anticipated on the PCB and it is have to do joining the components ( when is possible ) over the anticipated component by the old scheme (|es. C33 over R30, C31+R38 among pin1 R29 and pin1 R32 , etc...). If not is the space himself, join the component on the copper layer.
3. The change of R39 and R40 on LM318N (MY_ref_version2.pdf) has not to create problems. If you want try to use it not jeopardizes the operation and is enough join a res. as says Russ White. (I have joined a SMD 1206 over the LM318 pin...)
4. in the Thread evolution I have shown launch schemes, and this creates a lot of confusion. No problem. The gerber files are up-to-date, I praies do some verification and publish the Bom and serigraphy versions "identical" to the files.
Ciao
Mauro
1. The variations that propose are not obligatory and suggestion to try it with calm, after has built the first original circuit version.
2. order all the added of version 2 presents in the scheme My_ref_version2.pdf it is not anticipated on the PCB and it is have to do joining the components ( when is possible ) over the anticipated component by the old scheme (|es. C33 over R30, C31+R38 among pin1 R29 and pin1 R32 , etc...). If not is the space himself, join the component on the copper layer.
3. The change of R39 and R40 on LM318N (MY_ref_version2.pdf) has not to create problems. If you want try to use it not jeopardizes the operation and is enough join a res. as says Russ White. (I have joined a SMD 1206 over the LM318 pin...)
4. in the Thread evolution I have shown launch schemes, and this creates a lot of confusion. No problem. The gerber files are up-to-date, I praies do some verification and publish the Bom and serigraphy versions "identical" to the files.
Ciao
Mauro
Russ, that is the discordance?
The post #58 #59 am equal to my original files and to the gerber.
Precise statement:
The schemes of the last version of My_reference complete of layout PCB am that of the post #58 #59, with given 23_05_2005.
To avoid confusion, doesn't consider the serigraphy references of the versions previous to this date or the preceding post.
The my_ref_variant2.pdf file is equal of the post scheme #58 #59 but have been add the components of change:C30-31-32-33, R37-38-39-40, in increasing order. It doesn't foresee in the original BOM. This scheme serves only as drives for the changes, and the actual PCB has not it newses positions.
Naturally it be necessary confuse "MY_reference" with " Inverting GC variant ", what have a very similar serigraphy but the circuit is different!
Ciao
Mauro Penasa
The post #58 #59 am equal to my original files and to the gerber.
Precise statement:
The schemes of the last version of My_reference complete of layout PCB am that of the post #58 #59, with given 23_05_2005.
To avoid confusion, doesn't consider the serigraphy references of the versions previous to this date or the preceding post.
The my_ref_variant2.pdf file is equal of the post scheme #58 #59 but have been add the components of change:C30-31-32-33, R37-38-39-40, in increasing order. It doesn't foresee in the original BOM. This scheme serves only as drives for the changes, and the actual PCB has not it newses positions.
Naturally it be necessary confuse "MY_reference" with " Inverting GC variant ", what have a very similar serigraphy but the circuit is different!
Ciao
Mauro Penasa
Hi Mauro,
First, I am not sure there is any problem at all. I am still new enough to this that I realize it all could be my own misunderstanding.
Here is my understanding:
1) The gerbers you sent me are for the circuit based on the schematic titled "My_Reference Rev 'A' dated 09/05/2005".
2) The serigraphy mentioned above is for the same schematic.
3) The BOM is also based on that schematic.
It appears you have verified that. Thank you.
One reason I had doubts was that I see R8 and R9 on the serigraphy coming off pin 10 of the LM3886. But do not see those two resistors on the schematic.
Sorry if I am missing something obvious.
First, I am not sure there is any problem at all. I am still new enough to this that I realize it all could be my own misunderstanding.
Here is my understanding:
1) The gerbers you sent me are for the circuit based on the schematic titled "My_Reference Rev 'A' dated 09/05/2005".
2) The serigraphy mentioned above is for the same schematic.
3) The BOM is also based on that schematic.
It appears you have verified that. Thank you.
One reason I had doubts was that I see R8 and R9 on the serigraphy coming off pin 10 of the LM3886. But do not see those two resistors on the schematic.
Sorry if I am missing something obvious.
Member
Joined 2003
From the BOM for this project, I am trying to compile a parts list so that I can order all the required parts from Digi-key. Mainly there are only 3 parts that Digikey does not have, or at least an exact replacement, so for these parts I have replaced them as follows:
P_D (bridge rectifier): use 6GBU06, leads will have to be bent out a little to fit the PCB holes.
BC639: use ZTX453, transistor has different pinout so make sure it is installed properly
BZX85 (zener): 2EZ12D5D041
If there is anything I am missing, or anything you think there is a better replacement part for, please let me know, as I'm sure I'm not the only one trying to order all the parts from Digikey.
P_D (bridge rectifier): use 6GBU06, leads will have to be bent out a little to fit the PCB holes.
BC639: use ZTX453, transistor has different pinout so make sure it is installed properly
BZX85 (zener): 2EZ12D5D041
If there is anything I am missing, or anything you think there is a better replacement part for, please let me know, as I'm sure I'm not the only one trying to order all the parts from Digikey.
Member
Joined 2003
Just coppied and pasted your proper diode brige and -
Bingo bango GBJ804-FDI-ND
Found at : http://ca.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch
Mark
Bingo bango GBJ804-FDI-ND
Found at : http://ca.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch
Mark
Member
Joined 2003