First post on this forum. I have aquired the p-diyab-2v20 boards from the store, plus downloaded the build guide and bom. I am about to begin sourcing the required components to get on with this project. I have been reading through the 2 major threads and noticed there is a lot of discusion about certain part types and values etc, most of which, I admit I don't understand. My major concern is that if I follow the published BOM is that going to give me a satisfactory result? An area where an option is available, namely D3, what is that going to acheive? Also the G1 and G2 on the schematic, different potential? Forgive me for being technically inept when it comes to electronics, its not my first calling, but that doesn't dampen the interest.
Welcome aboard pthep.
I built my HB using the published BOM exactly, and am very happy with the sound. One catch is that the holes for D3/R18 are too small for the recommended D3. I was able to widen them with a 1/32" drill bit on a Dremmel.
Also, the recommended power resistors (R43 to R48) are no longer available, and no one (that I know of) has been able to find a replacement with the same lead spacing. So I mounted wirewound resistors standing upright, which is what I think others have done.
Have fun!
I built my HB using the published BOM exactly, and am very happy with the sound. One catch is that the holes for D3/R18 are too small for the recommended D3. I was able to widen them with a 1/32" drill bit on a Dremmel.
Also, the recommended power resistors (R43 to R48) are no longer available, and no one (that I know of) has been able to find a replacement with the same lead spacing. So I mounted wirewound resistors standing upright, which is what I think others have done.
Have fun!
To answer your other questions:
I didn't understand what is gained by the "zener reference design" over the "Luxman" way either. But the Luxman design was described as "crude" in the build guide, so I guessed it must be somehow inferior.
You can follow the trace from the ground-end of D1, D2 and R4 (G2) all the way to the star ground (G1) so they're not at different potentials. I really can't guess why they are written at G1 and G2 on the schematic.
I didn't understand what is gained by the "zener reference design" over the "Luxman" way either. But the Luxman design was described as "crude" in the build guide, so I guessed it must be somehow inferior.
You can follow the trace from the ground-end of D1, D2 and R4 (G2) all the way to the star ground (G1) so they're not at different potentials. I really can't guess why they are written at G1 and G2 on the schematic.
a ground is a ground is a ground, and a ground, should all have zero voltage...
regarding r18/d3, i pressolderd the resistor to the zener, clipped leads and soldered the combination into the board...
i had to enlarge some of the holes to facilitate lead insertions, a pcb drill came in handy...
regarding r18/d3, i pressolderd the resistor to the zener, clipped leads and soldered the combination into the board...
i had to enlarge some of the holes to facilitate lead insertions, a pcb drill came in handy...
I guess that depends on your definition of 'inferior'. A zener reference will maintain a constant voltage reference which is the same regardless of the voltage on the input voltage rails (within certain limits) while the Luxman simple resistor design will give a constant voltage that is proportional to the rail voltage and so may require a little calculation based on the planned voltage rails. Additionally, if there is variation on the voltage rail for any reason (such as voltage sag at high current draw) then the reference voltage will vary proportionally. How much of an issue those drawbacks represent is a matter of personal judgement, and for most users in most circumstances the simple Luxman style voltage divider will be adequate. However, for the tiny price difference I went for the zener reference.
As noted by others, some devices had _very_ tight lead clearances, and the zener was one of these for me, if I recall correctly. I didn't have to drill out any holes, but I did have to force a few leads through with more force than I would have liked.
My understanding of the differing grounds is that they are effectively 'local' grounds, all interconnected via a star system. It is used both to restrict tiny variations in potential and to allow 'noise' a direct path to earth rather than flowing past multiple devices. This is the basic principle behind star grounding. Although in theory an earth is always 0.00V and is uniform, the reality is that this is not always the case and star grounding helps limit adverse effects and current flows. The short story is that Ostripper has done all the hard design work and we get to use the fruits of his labour.
I have attached my BoM for the Honey Badger, as a Mouser shared cart available at the URL below. Note that for me at least this is based on Australian pricing.
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8080aaf520
Device selection was based on recommendations from Ostripper, component availability and price. Some items drift in and out of stock and so this will no doubt need some modification. Mouser stock a range of metal film resistors from TE Connectivity which I chose preferentially when possible as they are 600mW and a small form factor, but they didn't have stock in all values.
My selection preferences for electrolytic caps was long life and relatively low ESR, along with high voltage rating. This has resulted in a pair of relatively tall capacitors. I tried to use polypropylene rather than polyester caps for the audio signal path.
Note there there is no enameled wire, no heat sink compound and no Red LED.
I sourced the 0.22 ohm resistors from AnalogMetric. Lead spacing isn't exact but is easily widened.
Cement 0.2 Ohm 5W Non-inductance Resistor_Cement_Resistor_Analog Metric - DIY Audio Kit
I can attach a spreadhseet with my component selections if that's easier, otherwise I'll leave the Mouser BoM.
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8080aaf520
Device selection was based on recommendations from Ostripper, component availability and price. Some items drift in and out of stock and so this will no doubt need some modification. Mouser stock a range of metal film resistors from TE Connectivity which I chose preferentially when possible as they are 600mW and a small form factor, but they didn't have stock in all values.
My selection preferences for electrolytic caps was long life and relatively low ESR, along with high voltage rating. This has resulted in a pair of relatively tall capacitors. I tried to use polypropylene rather than polyester caps for the audio signal path.
Note there there is no enameled wire, no heat sink compound and no Red LED.
I sourced the 0.22 ohm resistors from AnalogMetric. Lead spacing isn't exact but is easily widened.
Cement 0.2 Ohm 5W Non-inductance Resistor_Cement_Resistor_Analog Metric - DIY Audio Kit
I can attach a spreadhseet with my component selections if that's easier, otherwise I'll leave the Mouser BoM.
Follow the build guide pg 28,
2.The small CCS just has a 20 turn 200R trimmer (R7). This CCS controls the LTP current. The small CSS can be adjusted between 1.8ma to almost 6ma, and this is achieved by adjusting R7 to between 70 and 100 ohms, which will result the desired output of 3.5ma at the "tail" of the LTP. 3.75mA gives roughly 8.25V across R14. Before powering on the amp, set R7 to 85ohms
James
2.The small CCS just has a 20 turn 200R trimmer (R7). This CCS controls the LTP current. The small CSS can be adjusted between 1.8ma to almost 6ma, and this is achieved by adjusting R7 to between 70 and 100 ohms, which will result the desired output of 3.5ma at the "tail" of the LTP. 3.75mA gives roughly 8.25V across R14. Before powering on the amp, set R7 to 85ohms
James
A few questions about the build...
If you are only seeking a single mono configuration would this transformer
http://www.antekinc.com/pdf/AN-5445.pdf
be an acceptable alternative to the recommended
http://www.antekinc.com/pdf/AN-8445.pdf
What is the maximum current required from the transformer for the Honey Badger?
Are there other models with lower ratings that could fully utilize this amp in mono?
What is the orientation of the Zener diode? - This was not clear on the PCB
-Phil
If you are only seeking a single mono configuration would this transformer
http://www.antekinc.com/pdf/AN-5445.pdf
be an acceptable alternative to the recommended
http://www.antekinc.com/pdf/AN-8445.pdf
What is the maximum current required from the transformer for the Honey Badger?
Are there other models with lower ratings that could fully utilize this amp in mono?
What is the orientation of the Zener diode? - This was not clear on the PCB
-Phil
Monobloc (or dualmono)? Probably the 400va will do fine. Antek - AS-4445 EDIT: This also looks good: Antek - AS-4440 for longevity/durability
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