haldor said:
I don't understand what the problem is. SHD was initially gnd, I didn't know it has been changed, what does it that matter anyway?
The pinout doesn't imply anything, it was all done to keep with symmetry. On the XLR connector 1 is still GND, 2 is still hot and 3 is still cold no matter what the pinout on the board is.
You can leave the SHD open and do the GND connection to the case with a 1/4 inch piece of solid conductor directly on the XLR connector. I doubt that will bring in much noise. Not everyone does have a perfect enclosure that is providing the perfect gnd connection and a perfect shielding.
In pro environment where everything is squeezed in a 1 unit rack the close proximity coupled to the shear number of gnds going around with all kinds of loops to keep track of the issues you brought up maybe a serious problem, in home applications I doubt it.
I will look at the links and try to make sense out of what you are saying.
Re: Hey Brian,
I am still skeptical about the quality of the gainclone. I know that has potential to sound good with good components. For me, the bottom line is that it is very cheap to build. My total parts cost for a 2 channel gainclone, including a $40 transformer is $80-90, while the Aleph-X is quite a lot more. My roommate, JordanG, is much more into the gainclone, and has a few in progress with different chassis designs, so I will let him find out what works best, and let him play with it. I will be sticking to the Aleph designs for my main speakers, and I am going to finish my first gainclone for my girlfriend some Tangband speakers, along with a gainclone and a sub for her own use with her computer. I think that I will also use a gainclone for my computer speakers, a pair of Jordan JX92S mini-monitors that I am working on.
Once I get some things finished, I will do a comparison of how the different amplifiers sound together. I should eventually get a stereo Aleph5, stereo Aleph-X and a few gainclone amps done to go along with my Leach amp. I just have so many projects, plus a busy school semester to deal with that I never seem to get but one project finished at a time. Now, my project is speakers. I think that once I get some output boards for my Aleph 5, I will finish it. I already have the chassis assembled and boards stuffed, I just need to wire it up with my transformer and other stuff.
pictures of my current projects in my gallery:
http://brian.darg.net/audio
--
Brian
carpenter said:
I am still skeptical about the quality of the gainclone. I know that has potential to sound good with good components. For me, the bottom line is that it is very cheap to build. My total parts cost for a 2 channel gainclone, including a $40 transformer is $80-90, while the Aleph-X is quite a lot more. My roommate, JordanG, is much more into the gainclone, and has a few in progress with different chassis designs, so I will let him find out what works best, and let him play with it. I will be sticking to the Aleph designs for my main speakers, and I am going to finish my first gainclone for my girlfriend some Tangband speakers, along with a gainclone and a sub for her own use with her computer. I think that I will also use a gainclone for my computer speakers, a pair of Jordan JX92S mini-monitors that I am working on.
Once I get some things finished, I will do a comparison of how the different amplifiers sound together. I should eventually get a stereo Aleph5, stereo Aleph-X and a few gainclone amps done to go along with my Leach amp. I just have so many projects, plus a busy school semester to deal with that I never seem to get but one project finished at a time. Now, my project is speakers. I think that once I get some output boards for my Aleph 5, I will finish it. I already have the chassis assembled and boards stuffed, I just need to wire it up with my transformer and other stuff.
pictures of my current projects in my gallery:
http://brian.darg.net/audio
--
Brian
WoW!!
My pcbs arrived in Athens(the ancient one) 2 day ago, I really have to admit that these are by far the best diy pcb I ever used! Too bad there is provision for only 2 pairs and not at least 4, for higher output, but I quess this is going to be the final diy touch!
Thanks again everybody involved in the accomplishment of this excellent project and logistics behind the huge distribution effort!
SUPER!
My pcbs arrived in Athens(the ancient one) 2 day ago, I really have to admit that these are by far the best diy pcb I ever used! Too bad there is provision for only 2 pairs and not at least 4, for higher output, but I quess this is going to be the final diy touch!
Thanks again everybody involved in the accomplishment of this excellent project and logistics behind the huge distribution effort!
SUPER!
grataku said:
Don't go getting upset now, there is nothing wrong with the PCB or the layout. The reason I mentioned the XLR pinout is because not everyone knows the correct pinout of an audio XLR (even some manufacturers still get pins 2 and 3 reversed). If someone who doesn't know better wires the XLR according to the pinout on the board then it is going to be wrong. No biggy, but worth mentioning in a cautionary sort of way.
The issue about not terminating the cable shield to the PCB is very real. Do a google search on "Pin 1 Problem" like I suggested and you will see what I mean. This has absolutely nothing to do with close proximity or tight quarters inside the enclosure. In fact, the effect will be worse if your enclosure is large and you have lengthy internal interconnects.
Phil
Mine finally arrived today - they look gorgeous!
Stupid Canada Post charged me $10.25 when I picked up my little envelope, though.
They also opened and "inspected" it and shredded the priority mail envelope Chad used to mail them, too, somehow. When I went to pick them up, I got a plastic bag with the PCBs rattling around in it, along with the remnants of the priority mail envelope. They're intact though, so it's not a big deal.
Thanks again to everybody who contributed!
Stupid Canada Post charged me $10.25 when I picked up my little envelope, though.
They also opened and "inspected" it and shredded the priority mail envelope Chad used to mail them, too, somehow. When I went to pick them up, I got a plastic bag with the PCBs rattling around in it, along with the remnants of the priority mail envelope. They're intact though, so it's not a big deal.
Thanks again to everybody who contributed!
Superb Quality
Chad and Team:
My boards arrived yesterday unopenned and in perfect shape in Toronto.
They are of the highest quality.
If you have not already done so you should add this project to your resume.
You now have references from around the World regarding a very succesful multi-part project.
Thanks for all the hard work.
Chad and Team:
My boards arrived yesterday unopenned and in perfect shape in Toronto.
They are of the highest quality.
If you have not already done so you should add this project to your resume.
You now have references from around the World regarding a very succesful multi-part project.
Thanks for all the hard work.
I see what Haldor was talking about! The ambiguity is on the schematic in the above post and on earlier schematics as well so please make a note.
The standard XLR connection is pin 1 GND, pin2 HOT (+), pin3 COLD (-).
The schematic seem to imply that the XLR connection should be
pin1 +in, pin2 GND, pin3 -in. That is INCORRECT. The board connector and the XLR connection are two separate entities. A switch in wiring should be made between the board connector and the actual XLR jack on the panel.
As conventions go, if you are driving the amp SE you probably won't see the problem, if you made up your BOSOZ with the same wrong conventions in the XLR outs you will not see a problem either.
As far as the Haldor point on grounding is concerned, experiment.
The so called "pin 1 problem" is as old as the oldest profession in the world (see Doug Self book on how he recommends doing the grounds). I don't know why that is coming back into fashion among the pro audio people.
Personally, I didn't have a problem carrying the GND from pin 1 on the XLR to the SHD pin on the board connector. This was probably because the SHD pin on the board goes to the star GND that is on the board. My guess is that if I didn't have a problem with it , neither will the other people building the circuit.
Ah, yes. Now I see what the fuss is about... let me reiterate some earlier comments on this:
The pinout notes in the corner of the schematic are for the PCB input connector only (misfortunately labelled 'XLR'), NOT an actual XLR-type jack mounted on the chassis. The comments and pinouts given on the schematic have no relation to any wiring which extends beyond the PCB itself. Note that this input connector pinout is labelled on the PCB silkscreen as well. You may use any one of a number of possible wiring combinations to suppy input to the board... unbalanced with coupling caps, balanced with DC coupling, etc, etc., including making use of the (good) suggestion to terminate a balanced cable's shield line to the chassis right at the jack. In all cases, it is up to you to determine and follow the proper pin connections and wiring for whatever connector jack you decide to use. If you are using XLR-type input jacks, then you can follow the pinout shown in red, in grataku's posting above.
The pinout notes in the corner of the schematic are for the PCB input connector only (misfortunately labelled 'XLR'), NOT an actual XLR-type jack mounted on the chassis. The comments and pinouts given on the schematic have no relation to any wiring which extends beyond the PCB itself. Note that this input connector pinout is labelled on the PCB silkscreen as well. You may use any one of a number of possible wiring combinations to suppy input to the board... unbalanced with coupling caps, balanced with DC coupling, etc, etc., including making use of the (good) suggestion to terminate a balanced cable's shield line to the chassis right at the jack. In all cases, it is up to you to determine and follow the proper pin connections and wiring for whatever connector jack you decide to use. If you are using XLR-type input jacks, then you can follow the pinout shown in red, in grataku's posting above.
I should also highlight the difference between the Shield or GND line, as used in balanced interconnect, vs. the GND connection as applied to unbalanced interconnects. In the case of balanced interconnect, the signal is carried by the + and - lines, and that is basically all that is required to convey the full signal information to the next piece of equipment. In this case, the GND or shield connection serves a role in screening the cable from outside interference. Thus, the term 'shield' is more appropriate to describe it's function. The connection is not strictly necessary in order for a balanced interconnect to function, although it does also serve to help keep the grounds of different pieces of equipment at the same potential, and can thus help prevent large common-mode voltages appearing at the inputs of a circuit. It is common for professional equipment to include a ground 'lift' switch to allow this shield to be disconnected, where safety ground paths are present through other connections - usually the mains power wiring. This ground can be useful in breaking noise-inducing ground loops, but care <i>must</i> be taken to ensure that all equipment is provided with a proper safety ground! And by the way... the shield line of a balanced interconnect does NOT qualify as a proper safety ground.
By contrast, unbalanced interconnect relies on the GND wire for use as a voltage reference for the signal line. Thus, both + and GND connections can be considered signals, as they play a direct role in conveying information between equipment. In this case, taking the GND 'signal' all the way to the PCB is actually very important if you want to avoid noise problems.
By contrast, unbalanced interconnect relies on the GND wire for use as a voltage reference for the signal line. Thus, both + and GND connections can be considered signals, as they play a direct role in conveying information between equipment. In this case, taking the GND 'signal' all the way to the PCB is actually very important if you want to avoid noise problems.
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