making many poor decisions in the past
I know the feeling of being able to make an amazing amplifier for very little money, but I have found that all of the compramises I have made in the past for inexpensive amplifiers and speakers of acceptable quality were just upgraded as soon as they are completed with components that were over looked just because of price, I have had so much junk in my posession at times it was imposible to see the TV or listen dirrectly to the current version of my speakers without having the sound bounce off piles of boxs of obsolite components. It is nice being able to make an expensive power supply without going crazzy with silver and gold transformers and coils, but if I had the money I would spend it without hesitation on the gold and silver items knowing that it is then an actual investment in gold and silver over time that will never loose its value, unfortunatly I am finacially crippled due to my medical disability, Heroin and cocaine addiction, I dont take any anymore but I still will have to take medication for the rest of my life, methadone and imovane, it is provided for free here in Canada along with a cheque for $1,200.00 a month to people who clame the addiction is a medical problem.
Sorry for going on and on about nothing.
I will probibly never finish my paper on "A General Counting Theory", I have other projects that I can get government grants for working on that will probibly be done first, but are not as important to the general knowlage of mankind, my spelling is poor if there are spelling mistakes.
The coils I have now I think I will use and purchase the foil coils to complete the speakers the way they should be done, the 2.2mH & 7.5mH coils are the only ones that are 10gage copper wire, all of the others are 12gage copper foil.
Thank You for listening, I sence honesty here that I do not get anywhere else in my life, everything seems to be about how much money you have in the bank with the people(girls) I meet and nothing else, none of them care about my stereo problems, or solutions.
I know the feeling of being able to make an amazing amplifier for very little money, but I have found that all of the compramises I have made in the past for inexpensive amplifiers and speakers of acceptable quality were just upgraded as soon as they are completed with components that were over looked just because of price, I have had so much junk in my posession at times it was imposible to see the TV or listen dirrectly to the current version of my speakers without having the sound bounce off piles of boxs of obsolite components. It is nice being able to make an expensive power supply without going crazzy with silver and gold transformers and coils, but if I had the money I would spend it without hesitation on the gold and silver items knowing that it is then an actual investment in gold and silver over time that will never loose its value, unfortunatly I am finacially crippled due to my medical disability, Heroin and cocaine addiction, I dont take any anymore but I still will have to take medication for the rest of my life, methadone and imovane, it is provided for free here in Canada along with a cheque for $1,200.00 a month to people who clame the addiction is a medical problem.
Sorry for going on and on about nothing.
I will probibly never finish my paper on "A General Counting Theory", I have other projects that I can get government grants for working on that will probibly be done first, but are not as important to the general knowlage of mankind, my spelling is poor if there are spelling mistakes.
The coils I have now I think I will use and purchase the foil coils to complete the speakers the way they should be done, the 2.2mH & 7.5mH coils are the only ones that are 10gage copper wire, all of the others are 12gage copper foil.
Thank You for listening, I sence honesty here that I do not get anywhere else in my life, everything seems to be about how much money you have in the bank with the people(girls) I meet and nothing else, none of them care about my stereo problems, or solutions.
True.
If only we could all go down the pub together and have a drink to that.
Post a picture when you are finished.
Aleph X-J pcb bill of materials incomplete
I am now looking to order the components to fill the pcb boards for an ALeph J-X, I have ordered the power supply components and now must look into what is required for the three part printed circuit board (pcb). On the first look into the bom I have found that there is no value on the middle bridge board for P1, or RS located above R4, or RP located above R5 ? Is there anything else I have missed or over looked ?
Thank You for your continued help.
I am now looking to order the components to fill the pcb boards for an ALeph J-X, I have ordered the power supply components and now must look into what is required for the three part printed circuit board (pcb). On the first look into the bom I have found that there is no value on the middle bridge board for P1, or RS located above R4, or RP located above R5 ? Is there anything else I have missed or over looked ?
Thank You for your continued help.
I have ordered a camera and tripod to post all of the steps taken to assemble my Aleph J-X mono amplifier pair. It was difficult desiding what camera to buy because there are so meny with outragious specifications for so little money since I purchased my last camera which was stolen from my house along with my telescope about 15years ago. I ordered a demo "Fuji Finepix 12MP Digital Camera S1800" for $159.00, plus 16GB of memory, and a case, and a tripod, and a beginers package that includes a memory card reader for the computer and a small table tripod, and 2GB of memory, and lens cleaner items, along with some other stuff for an additional $9.00.
I will begin posting pictures as soon as I have purchased and recieved all of the components for my pair of Aleph J-X mono blocks.
I will begin posting pictures as soon as I have purchased and recieved all of the components for my pair of Aleph J-X mono blocks.
I am using twelve not eight MOSFETs
I am using all twelve spaces for the MOSFETs, I am also planning on using fans as well for the additional heat, how do you set the "bias" on these amps, or which resister sets the "bias" so I can use a variable resistor insted if posible ?
I am using all twelve spaces for the MOSFETs, I am also planning on using fans as well for the additional heat, how do you set the "bias" on these amps, or which resister sets the "bias" so I can use a variable resistor insted if posible ?
P1 & RS & RP components are not known to me yet
I am now looking to order the components to fill the pcb boards for an ALeph J-X, I have ordered the power supply components and now must look into what is required for the three part printed circuit board (pcb). On the first look into the bom I have found that there is no value on the middle bridge board for P1, or RS located above R4, or RP located above R5 ? Is there anything else I have missed or over looked ?
Thank You for your continued help.
I am now looking to order the components to fill the pcb boards for an ALeph J-X, I have ordered the power supply components and now must look into what is required for the three part printed circuit board (pcb). On the first look into the bom I have found that there is no value on the middle bridge board for P1, or RS located above R4, or RP located above R5 ? Is there anything else I have missed or over looked ?
Thank You for your continued help.
Not sure which schematic you are using, but P1 depends on the CCS configuration you are using. 200R should be OK.
RS (based on an early sketch of the schematic by Peter) is for DC offset stability. Somewhere between 2K and 22K have been used. Buy several values to see what works.
Not sure what Rp is without the schematic you're using. My guess is it is in the CCS and again depends on the CCS configuration you use (bipolar or JFET)
Bias is set by the source resistors. Not really practical to make them variable. There is a resistor in the active current source that can be used to give some bias adjustability, maybe 20% or so. Earlier AX designs used pots to allow some relative offset adjustment. Point to your schematic I can tell you which one - it is the one between the base of the ACS ZTX450 and the junction of the bootstrap capacitor above the ZTX collector. Higher values increase bias, lower values decrease to a point. It should be around 100K on your schematic.
Greg, the issue is not bias but the ability to drive the gate capacitance of the outputs. If the circuit is set up to drive an X amp with 3 pairs of outputs per side, then a single side with three output pairs should be fine.
RS (based on an early sketch of the schematic by Peter) is for DC offset stability. Somewhere between 2K and 22K have been used. Buy several values to see what works.
Not sure what Rp is without the schematic you're using. My guess is it is in the CCS and again depends on the CCS configuration you use (bipolar or JFET)
Bias is set by the source resistors. Not really practical to make them variable. There is a resistor in the active current source that can be used to give some bias adjustability, maybe 20% or so. Earlier AX designs used pots to allow some relative offset adjustment. Point to your schematic I can tell you which one - it is the one between the base of the ACS ZTX450 and the junction of the bootstrap capacitor above the ZTX collector. Higher values increase bias, lower values decrease to a point. It should be around 100K on your schematic.
Greg, the issue is not bias but the ability to drive the gate capacitance of the outputs. If the circuit is set up to drive an X amp with 3 pairs of outputs per side, then a single side with three output pairs should be fine.
Greg, you can parallel the jfets using matched quads to eliminate any doubt about drive capability. Don't forget to use the corresponding number of sense Rs on the output to keep the current gain ratio the same.
As Bob has said, the output bias is set by the circuit monitoring only a single output pair. Hanging more pairs on the output will increase the overall bias current proportional to the number of pairs added. If you go from 2 prs to 3 prs your overall bias current will increase 50%.
As Bob has said, the output bias is set by the circuit monitoring only a single output pair. Hanging more pairs on the output will increase the overall bias current proportional to the number of pairs added. If you go from 2 prs to 3 prs your overall bias current will increase 50%.
On a car, the left and right front tires need to be same.
Left and right tires at the back need to be identical as well.
Doesn't mean you need 4 identical matched tires.
The J uses feedback, feedback makes the left and right amp operate identical.
Reversed : for identical L+R operation, overall gain should be exactly the same (exact same feedback factor)
Left and right tires at the back need to be identical as well.
Doesn't mean you need 4 identical matched tires.
The J uses feedback, feedback makes the left and right amp operate identical.
Reversed : for identical L+R operation, overall gain should be exactly the same (exact same feedback factor)
There are several AJ-X schematics floating around that don't all use the same parts designation - please post (a link is OK) the one you are using. The schematic I've attached is probably very similar (I think your schematic has only two 2SJ109s and isn't cascoded), but I haven't had the time to dig through this thread to find Peter's final schematic.
A CCS can be made from a BJT, Mosfet, JFET, constant current diode, vacuum tube and 3 terminal voltage regulator and probably other devices. Topologies are similar but values device dependent. I recall that there was some discussion earlier in this and other threads about using a JFET CCS and the sonic merits of various types. Sorry to throw another decision into the mix.
Scaiff,
Reading from here http://www.diyaudio.com/forums/pass-labs/145387-aleph-j-x-amp-project-27.html#post2005744 may answer your questions. That may be the final schematic. Found it with a search on Rp and show results as posts.
Reading from here http://www.diyaudio.com/forums/pass-labs/145387-aleph-j-x-amp-project-27.html#post2005744 may answer your questions. That may be the final schematic. Found it with a search on Rp and show results as posts.
I have recieved my Electrolytic Capacitors for my power supply, 36 of these capacitors looks like allot of them, 18 for each mono amp, I have also recieved my two shielded 600VA transformers which look huge for a 30+watt amp.
I have ordered a camera so I can document the assembly of this amp and post it.
I have begun to look at the components listed on the BofM given for the project, I have noticed that the 1,000hrs 85degree "Panasonic EUUFC series" electrolytic capacitors suggested on the BofM are not wise choices, I am ordering the 20,000hrs 105degree "Nichicon PX series" capacitors or the 8,000hrs 105degree low impedance "Nichicon PW series", I have not looked at the effect the capacitors impedance will have on the circuit yet, then I will make a choice.
Dose anyone have an idea how the different impedance of the PX or PW capacitor will have on the circuit for "C2" & "C3 & C4" on the schematic(s) Bill of Materials ?
Thank You for your help
I have ordered a camera so I can document the assembly of this amp and post it.
I have begun to look at the components listed on the BofM given for the project, I have noticed that the 1,000hrs 85degree "Panasonic EUUFC series" electrolytic capacitors suggested on the BofM are not wise choices, I am ordering the 20,000hrs 105degree "Nichicon PX series" capacitors or the 8,000hrs 105degree low impedance "Nichicon PW series", I have not looked at the effect the capacitors impedance will have on the circuit yet, then I will make a choice.
Dose anyone have an idea how the different impedance of the PX or PW capacitor will have on the circuit for "C2" & "C3 & C4" on the schematic(s) Bill of Materials ?
Thank You for your help
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