Did you try listening with a lower impedance headphone? That would raise the corner frequency of the bypass, so you'd hear the electrolytics covering more of the sound spectrum. Or you could just listen without a bypass in place, or try a much smaller bypass value. I think you must be right though. With 250 ohm cans the 1uF WIMA bypass dominates the sound signature to the point that electrolytic selection may not matter much.
My lower impedance cans are Sony MDRV6 about 60ohms. One side (left) is damaged from an unfortunate incident with a DC coupled amp where a component on one 20v rail of a +/-20v rail let loose with the headphones connected. I heard a pop and a fizz sound.
So only right channel works now. I would like to get them fixed but replacement driver is $40 and new phones is $70. I am a bit leery of DC coupled amps now. The Agdr Super CMOY has a lot of built circuits (comparator and mosfet opto switches) to protect against rail imbalance. It's s lot of work. Why not just cap couple.
a little late to the party, but are there any plans to make a board using mostly through hole components?
for me its not so much an issue of soldering but more an issue of sourcing SMDs. There's not many places I know of in Australia to get SMDs, and of those they do usually have minimum order quantities - eg, SMD resistors are minimum order of 50 at RS components...surprisingly the FETs can be ordered singly haha.....
for me its not so much an issue of soldering but more an issue of sourcing SMDs. There's not many places I know of in Australia to get SMDs, and of those they do usually have minimum order quantities - eg, SMD resistors are minimum order of 50 at RS components...surprisingly the FETs can be ordered singly haha.....
welcome to the party! it's true there's usually a minimal qty for SMD resistors, but they are pretty cheap, depending on where you get them. you can have 100 for under a dollar or so. and getting the exact quantity you need is probably not a good idea anyway, it's pretty easy to lose a tiny 0805 resistor. if you only need the SMD parts, i can mail some to you at no cost (except for the transistors, as i dont have any left at the moment, but i'm getting some soon). send me a PM if interested.
Bogde,
That's mighty nice of you to offer to send SMT's care package from Finland (IIRC) to Australia!
Yourownbuzz,
My suggestion is to order about 100 ea. At least in the US with Digikey itnworks out to be the most economical at $0.77 for 100. SMT resistors are superior to through hole equivalents in many ways. Most importantly they allow a very tight layout with only mm in between the critical front end network where stray noise pickup can be an issue. One of the reasons this amp has such clean low noise performance is in part, the very tight layout using SMTs. I don't have any plans for a through hole board. It won't fit in a mint tin.
That's mighty nice of you to offer to send SMT's care package from Finland (IIRC) to Australia!
Yourownbuzz,
My suggestion is to order about 100 ea. At least in the US with Digikey itnworks out to be the most economical at $0.77 for 100. SMT resistors are superior to through hole equivalents in many ways. Most importantly they allow a very tight layout with only mm in between the critical front end network where stray noise pickup can be an issue. One of the reasons this amp has such clean low noise performance is in part, the very tight layout using SMTs. I don't have any plans for a through hole board. It won't fit in a mint tin.
i figured that since those components are so tiny i can put them in an envelope and send them as a regular letter for cheap. i _didn't check_, to be honest, but it shouldn't be more than one euro or so. and the components are practically nothing since i got a lot more than i needed (i'm talking about the smd resistors and caps).
honestly, i was hoping more people would _actually_ join the party and share their builds and experiences, i think only three or four gave feedback after building their amps.
however, this was the first time i actually joined a GB here on diyaudio, that's probably why i'm so excited, so please don't mind me. cheers!
honestly, i was hoping more people would _actually_ join the party and share their builds and experiences, i think only three or four gave feedback after building their amps.
however, this was the first time i actually joined a GB here on diyaudio, that's probably why i'm so excited, so please don't mind me. cheers!
Yes more boards are available.
Bogde,
I am hoping that it's because folks are not as fast as building their amps as you and the few others that we have not heard more. It sometimes can take a while to gather parts of ne hasn't ordered the BOM prior to ordering the board. One thing about this amp though is it is an easy build. I have had 100% sucess rate (7 amps) with builds running the first time at first power-on. That's actually rare for me.
Bogde,
I am hoping that it's because folks are not as fast as building their amps as you and the few others that we have not heard more. It sometimes can take a while to gather parts of ne hasn't ordered the BOM prior to ordering the board. One thing about this amp though is it is an easy build. I have had 100% sucess rate (7 amps) with builds running the first time at first power-on. That's actually rare for me.
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Those Sonys are classic. When I took piano lessons as a kid in the nineties, my piano teacher had a pair of those exact 'phones permanently affixed to a synthesizer in her living room. When my lesson on the real piano was over and it was my brother's turn for his lesson, I would eagerly go sit down, put on those Sonys, and just mess around with cheesy synth sounds for an hour. It was pretty awesome.
"...Why not just cap couple?" For maximum transparency, maybe? Did you just hint that an output capacitor-less (OCL) version of this amp might be possible?
I for one would be very interested in that option, even if it was extra work.
It is a lot more work and I looked into designing such an amp. It would require an opamp servo to maintain zero DC offset. It would necessitate a relay to prevent turn on thump which could blow a headphone. It would require dual voltage supply rails (twice the components for the PSU alone) and you would probably cap couple the input stage anyway to prevent your source DC from blowing your cans. So it's not like you are completely skipping caps. Although if you are sure your source is AC coupled already, you could skip the input caps.
Anyhow, themany negative trafeoffs is sort of not inspiring me to pursue this.
However, I have embarked on the next super desktop amp with 4w of output capability into 50ohm cans and can drive 8ohm speakers to 10w even. Still SE Class A with CFP topology. Hugh Dean has been a very generous and super helpful in providing me a wonderful amp design to go with here. Initial sims are very encouraging - predicted FFT for 320mW into 50ohms (4v p-p) is 0.04%THD with a harminic profile similar to this pocket amp.
Anyhow, themany negative trafeoffs is sort of not inspiring me to pursue this.
However, I have embarked on the next super desktop amp with 4w of output capability into 50ohm cans and can drive 8ohm speakers to 10w even. Still SE Class A with CFP topology. Hugh Dean has been a very generous and super helpful in providing me a wonderful amp design to go with here. Initial sims are very encouraging - predicted FFT for 320mW into 50ohms (4v p-p) is 0.04%THD with a harminic profile similar to this pocket amp.
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If anyone wants the whole BOM from one source, I think I've got everything on this cart from Digikey:
Invalid Request
Epcos through hole film caps and a Bourns pot (sorry WIMA and Alps crowd).
$26
Invalid Request
Epcos through hole film caps and a Bourns pot (sorry WIMA and Alps crowd).
$26
Thanks Sodacose. That makes it much easier for some of us who are diehard Digikey fans or just plain lazy
Epcos is good stuff. Just doesn't come in a cool red molded package. Bourns is good too however I prefer look of that machined aluminum shaft over a die-cast knurled split shaft. No one will know once knob is on though.
Epcos is good stuff. Just doesn't come in a cool red molded package. Bourns is good too however I prefer look of that machined aluminum shaft over a die-cast knurled split shaft. No one will know once knob is on though.
Bodge & xrk971 - you guys were right, the SMD resistors don't cost that much even when the minimum order is 100. Turns out the SMD parts were the easy part to get ahold of.....
I've managed to find most of the components... With the ones I'm having trouble with, will these caps be suitable substitutes for the WIMA ones? Looking at the sizes these are physically a bit bigger....(WIMA are available...but the shipping costs of Farnell/element14 make it quite silly... AU$12 postage for a few dollars in caps)
B32529D0225J000 | EPCOS 2.2μF Polyester Capacitor PET 63 V dc 5% B32529 Series | EPCOS
B32529C0105J000 | EPCOS 1μF Polyester Capacitor PET 63 V dc 5% B32529 Series | EPCOS
And does anyone know of any suitable substitutes for the Switchcraft connector? They are available, but the price is a little crazy.. AU$30 for a pack of 5, when I see digikey has them for about US$2....
I've managed to find most of the components... With the ones I'm having trouble with, will these caps be suitable substitutes for the WIMA ones? Looking at the sizes these are physically a bit bigger....(WIMA are available...but the shipping costs of Farnell/element14 make it quite silly... AU$12 postage for a few dollars in caps)
B32529D0225J000 | EPCOS 2.2μF Polyester Capacitor PET 63 V dc 5% B32529 Series | EPCOS
B32529C0105J000 | EPCOS 1μF Polyester Capacitor PET 63 V dc 5% B32529 Series | EPCOS
And does anyone know of any suitable substitutes for the Switchcraft connector? They are available, but the price is a little crazy.. AU$30 for a pack of 5, when I see digikey has them for about US$2....
i think the 1uF will fit, but the 2.2uF wont. but i think you could try to solder one of them on the smd side, or use 1uF everywhere (but you should probably wait for X to share his opinion on that). X also shared an alternative build in this post: http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-42.html#post5019147
Those Switchcraft are special fit to the board. I have seen a low cost (not as high quality) option on aliexpress but in qnty 200 for $40.
200PCS/lot 5PIN 1/8" 3.5mm Jack Stereo Headphones Socket nut PCB Panel Mount Chassis from ruinor freeshippng-in Connectors from Home Improvement on Aliexpress.com | Alibaba Group
Not sure that helps though.
200PCS/lot 5PIN 1/8" 3.5mm Jack Stereo Headphones Socket nut PCB Panel Mount Chassis from ruinor freeshippng-in Connectors from Home Improvement on Aliexpress.com | Alibaba Group
Not sure that helps though.
GB2 Update
Quote:
Turbon - 1 board and 2 sets matched FETs - SHIPPED
Schlomoff - 1 built and tested board and 4 SMT populated boards with matched FETs - DELIVERED Mar 11 (per tracking no.)
pranavkr - 1 board - SHIPPED
Potatowedge - 2 boards and 1 set of matched FETs - RECEIVED
pcgab - 2 boards - SHIPPED - RECEIVED
bogde - 4 boards - SHIPPED - RECEIVED
adn6244 - 2 boards - SHIPPED - RECEIVED
tcpoint - 2 boards - SHIPPED
funch - 2 boards and 2 matched sets of FETs - RECEIVED
Wanfai - 1 board and 1 matched sets of FETs - SHIPPED
883bkong - 2 boards - SHIPPED
Kylej1015 - 2 boards - SHIPPED - RECEIVED
Jammer55 - 4 boards - SHIPPED
Tupam - 2 boards - SHIPPED - RECEIVED
aud1out - 2 boards - SHIPPED - RECEIVED
tommylck - 2 boards & 2 sets of matched FETs - SHIPPED
slaterlovesspam (Head-Fi.org) - 1 PCB and 1 special parts kit - RECEIVED
drpro - 1 board & 1 set of FETs - SHIPPED
mds2004 (head-fi.org) - 4 boards & 4 sets of FETs - SHIPPED
Gikigill (head-fi.org) - 1 fully built NHB amp with desktop convertible option - SHIPPED
Quote:
Turbon - 1 board and 2 sets matched FETs - SHIPPED
Schlomoff - 1 built and tested board and 4 SMT populated boards with matched FETs - DELIVERED Mar 11 (per tracking no.)
pranavkr - 1 board - SHIPPED
Potatowedge - 2 boards and 1 set of matched FETs - RECEIVED
pcgab - 2 boards - SHIPPED - RECEIVED
bogde - 4 boards - SHIPPED - RECEIVED
adn6244 - 2 boards - SHIPPED - RECEIVED
tcpoint - 2 boards - SHIPPED
funch - 2 boards and 2 matched sets of FETs - RECEIVED
Wanfai - 1 board and 1 matched sets of FETs - SHIPPED
883bkong - 2 boards - SHIPPED
Kylej1015 - 2 boards - SHIPPED - RECEIVED
Jammer55 - 4 boards - SHIPPED
Tupam - 2 boards - SHIPPED - RECEIVED
aud1out - 2 boards - SHIPPED - RECEIVED
tommylck - 2 boards & 2 sets of matched FETs - SHIPPED
slaterlovesspam (Head-Fi.org) - 1 PCB and 1 special parts kit - RECEIVED
drpro - 1 board & 1 set of FETs - SHIPPED
mds2004 (head-fi.org) - 4 boards & 4 sets of FETs - SHIPPED
Gikigill (head-fi.org) - 1 fully built NHB amp with desktop convertible option - SHIPPED