GeorgeBoles said:
Hi George, yes i meant the Zen 3 article.
I took a close look at your boardlayout, and I didnt find anything wrong. You should consider widening the tracks going from R34 to Q7, and from R26 to Q6 since they carry a lot of current. Actually I like the design, its pretty nicely layed out. Good work, George. I like the coupling caps
If you consider having protoboards made, i would like to be signed up for a pair
Steen
Hi Steenoe,
Thank-you for your thoughts. You might have missed where I wrote that those tracks are to be 5.5mm thick, and I just printed them out 1.0mm so that you could see the detail of the Bottom Copper layer.
Do you think I should go thicker than 5.5mm? I can go to 6.5mm, but after that the board starts to get crowded.
Regards,
George.
P.S. Unfortunately I have no way of making prototype boards ... just my wife's iron and Toner Transfer, and the quality for that varies a LOT when I do it!
Here is the Circad98 file if anyone is interested. It just needs the ground connections on the Top Copper layer to be put in. You will have to remove the .zip extension to get it back to the Circad98 .pcb file.
Thank-you for your thoughts. You might have missed where I wrote that those tracks are to be 5.5mm thick, and I just printed them out 1.0mm so that you could see the detail of the Bottom Copper layer.
Do you think I should go thicker than 5.5mm? I can go to 6.5mm, but after that the board starts to get crowded.
Regards,
George.
P.S. Unfortunately I have no way of making prototype boards ... just my wife's iron and Toner Transfer, and the quality for that varies a LOT when I do it!
Here is the Circad98 file if anyone is interested. It just needs the ground connections on the Top Copper layer to be put in. You will have to remove the .zip extension to get it back to the Circad98 .pcb file.
Those low Ohm high power resistors
Hi Choky,
Do you suggest that we use wire-wound resistors for the 0.22 ohm (0.33 ohm in the Babelfish-JX)?
The lowest ohm metal film resistors from Panasonic appear to be 0.47 ohm, which appears to be what everyone else uses as "standard".
I am probably worrying too much, I suppose, but the wire-wound will have some inductance ... problem or not?
Just chasing up these parts and I will be soldering!
Regards,
George.
Hi Choky,
Do you suggest that we use wire-wound resistors for the 0.22 ohm (0.33 ohm in the Babelfish-JX)?
The lowest ohm metal film resistors from Panasonic appear to be 0.47 ohm, which appears to be what everyone else uses as "standard".
I am probably worrying too much, I suppose, but the wire-wound will have some inductance ... problem or not?
Just chasing up these parts and I will be soldering!
Regards,
George.
Re: Those low Ohm high power resistors
Hi George
Its pefectly okay to parallel smaller wattage resistors. Say you can get 1 watt metalfilm (metalfilm is preferred for source resisors) paralleling 4 pcs 1r's will get you there. The absolute value is not wildly important. Match the value of the source resistors as good as you can.
Usually when adjusting the bias on the finished amp, finding that you cant hit the target, you simply adjust the value of the resistor that sits in series with the bias-trimpot, up or down, whatever is needed. Its not needed to change the source resistors. At least I didnt have to, yet.
Steen
GeorgeBoles said:
Hi George
Its pefectly okay to parallel smaller wattage resistors. Say you can get 1 watt metalfilm (metalfilm is preferred for source resisors) paralleling 4 pcs 1r's will get you there. The absolute value is not wildly important. Match the value of the source resistors as good as you can.
Usually when adjusting the bias on the finished amp, finding that you cant hit the target, you simply adjust the value of the resistor that sits in series with the bias-trimpot, up or down, whatever is needed. Its not needed to change the source resistors. At least I didnt have to, yet.
Steen
Re: Those low Ohm high power resistors
I'm way slower than Lucky Luke's shadow,and he's faster than his own shadow .........
well, you both have right answers
Yunick- I remember that I wrote you about that resistor for increasing bias
btw - wirewounds are still decent, at least in A class amps,not in those sissy C class KSAxx thingies ........
GeorgeBoles said:
Yunick said:There is a possibillity to parallell two panasonic 0.47 ohm for 0.235ohm
I have not tried that, but I use 0.27ohm wire wound.., This will not rais the bias enough in my babbelfish.. Ended up with 1.8A per side..
However my amp sounds great with wirewound resistors..
I'm way slower than Lucky Luke's shadow,and he's faster than his own shadow .........
well, you both have right answers
Yunick- I remember that I wrote you about that resistor for increasing bias
btw - wirewounds are still decent, at least in A class amps,not in those sissy C class KSAxx thingies ........
Khron said:Hi Choky / Zen Mod
I hope you'll find time one of these days, to advise me of the (exact) changes necesary to make a headphone amp out of your Babelfish
well - something like this
output mosfets - probably any of IRF5x0 or IRF6x0 thingies
for exact tweaking of output current - just play little with value of R13 , besides turning left and right funny WR2 ( increasing R13 increase current and vice versa ) .
schematic as is is drawn for approx. 500mA of current ;
it's wise to try - after finishing and setting circuit - switching off modulation of output CCS ( lifting one ond of R14, so base of R4 doesn't get modulation from output ) so output CCS is no more Aleph one ,but plain vanilla CCS
in that case little one became pure SE
if you have more Qs , just shoot
btw - that drek will make AKG 1000 sing like crazy
like always - all cudos to Papa
Attachments
I can't thank you enough for the assistance, and sorry for being so nagging
I hope these details will also help others... Or maybe even make this a "Babelfish HP" (for HeadPhones )
Thanks again,
Chris
Edit: If anyone's interested, i re-created the general layout of the Babelfish in Eagle, but i also customized it to my needs (film cap sizes and balanced input only). If anyone's interested, i could post the schematic and layout
I hope these details will also help others... Or maybe even make this a "Babelfish HP" (for HeadPhones
)Thanks again,
Chris
Edit: If anyone's interested, i re-created the general layout of the Babelfish in Eagle, but i also customized it to my needs (film cap sizes and balanced input only). If anyone's interested, i could post the schematic and layout
Khron said:........
I hope these details will also help others... Or maybe even make this a "Babelfish HP" (for HeadPhones
..........
I forgot to say - one of things (maybe ) needed for HP use is changing of overall gain ;
that is easy too, but I don't wanna scribe this now, because I'm lazy to cover both - balanced and unbalanced variant at once...
Khron said:Wouldn't reducing the 220k feedback R be enough to reduce gain?
exactly ;
but not reducing it to less than , say , 110K ;
wel , while we are at it - in both cases ( bal & unbal) you must reduce R9 and R2 in same time, to same value............. without digging in actual problematic of real differential gain,impedance etc.....
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