According to X's post a few days back there were boards still available:
http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-48.html#post5026205
http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-48.html#post5026205
So, contacted the ali seller about smaller quantities, neither wanted to do it, and at $40ish for some 200 connectors... well the price is right but the quantity is ridiculous!
I found these on ebay, 10PCS 3.5mm Stereo Female Socket Audio Jack 5Pin PCB Panel Mount Connector Black | eBay
I think they will work but obviously ones with nuts would be preferable for mounting....
xrk971 - if say I wanted two boards would you be able/willing to stick some sockets in along with them (happy to pay cost of the connectors, unless it works out to be more than US$4.50 each)? or would that change the postage costs?
I found these on ebay, 10PCS 3.5mm Stereo Female Socket Audio Jack 5Pin PCB Panel Mount Connector Black | eBay
I think they will work but obviously ones with nuts would be preferable for mounting....
xrk971 - if say I wanted two boards would you be able/willing to stick some sockets in along with them (happy to pay cost of the connectors, unless it works out to be more than US$4.50 each)? or would that change the postage costs?
Those eBay units won't work as pin locations not correct. Also you need the screw mounts.
I can get you the 3.5mm plugs but shipping does indeed go up. It's a "package" now and that adds about $5. The 3.5mm jacks (not plugs) are $2.50. ea. So $10 extra for a set of two Switchcraft 3.5mm jacks added. But you get USPS priority mail with tracking and it comes in 2 days.
Yeah, even if those ebay ones had fit it would've been less than ideal.
Surprisingly, one of the local suppliers has dropped their price to a more reasonable AU$3.4 (US$2.50) per socket (let's hope that they don't raise it back up before I can order...)!
Thanks xrk971 for being willing to post the sockets, but I guess now I can just buy it locally.
xrk971 - could I get two boards please?
Surprisingly, one of the local suppliers has dropped their price to a more reasonable AU$3.4 (US$2.50) per socket (let's hope that they don't raise it back up before I can order...)!
Thanks xrk971 for being willing to post the sockets, but I guess now I can just buy it locally.
xrk971 - could I get two boards please?
New photos for eBay listing - special limited time pricing of complete amp ready to use.
Pocket Class A Headphone Amplifier / Desktop Amplifier | eBay
Pocket Class A Headphone Amplifier / Desktop Amplifier | eBay
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I see nothing special about the price... Except that you are profiting upwards of $120 for an amp built on PCBs laid out by someone else, from a circuit which was largely optimized via the suggestions of someone else... Where is their credit? Are they paid for their effort which helped bring this project to fruition?
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Needtubes,
People are still welcome to build the DIY version themselves for cost of the board ($12). The labor that goes into making these info a fully functional and tested amp is substantial - what I am offering here for those either unable or who don't have time to make it themselves. Credit for layout fully goes to BDHM with the initial outline of board shape and pots/jacks provided by Agdr. As far as the design of the circuit - this was developed with Hugh's help but it is my design. I don't think anyone is complaining except you.
People are still welcome to build the DIY version themselves for cost of the board ($12). The labor that goes into making these info a fully functional and tested amp is substantial - what I am offering here for those either unable or who don't have time to make it themselves. Credit for layout fully goes to BDHM with the initial outline of board shape and pots/jacks provided by Agdr. As far as the design of the circuit - this was developed with Hugh's help but it is my design. I don't think anyone is complaining except you.
needtubes,
have you ever built any amps/headamps/preamps...? I think you must have... have you stopped for moment to think the effort spent? its enormous. can you value it?
I have built some complete amps, I know the effort and time that goes into building and testing them....
most will agree that xrk has created a piece of equipment that can beat the best commercial offerings, so the price is fair for the effort spent, as he has the go ahead from AKSA, BDHM and ADGR. If it was a mass produced item, yes, I agree that price could be lower, but unfortunately its not..., its all effort and time of a single person. I hope I can get hold of one too, but simply not in a financial position to do so... hopefully xrk can somehow mass produce offer at a lower price, i will take it.
why should you have a problem with the price?
best regards
Prasi
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Some playing around with my personal cap-rolling test-bed.
On inputs: Wima 2.2uF + Elna Silmic II 4.7uF
On outputs: Wima 1uF + Elna Silmic II 100uF + Panasonic OSCON 390uF
On power rails: no-name (Chongx) 2200uF 24v (12mm dia x 20mm long fits) this will let me try a higher power supply voltage of 19v.
Spent some time last night listening to it - very very nice combo and fits nicely on the board. Super bass extension and midgrange smoothness and treble clarity with no harshness or sibillance. I just got some DT770-250's for a friend and listened to them for a while. I like the DT880-250's better. The 770's are sealed back and bass reflex (with a small port) - they isolate sound well, but for my ears, sound a tad too bright. Looking at measured curves shows more HF extension and a peak near 10k compared to 880's. If your hearing is soft on the highs, you may like 770's better for their treble enhancement.
On inputs: Wima 2.2uF + Elna Silmic II 4.7uF
On outputs: Wima 1uF + Elna Silmic II 100uF + Panasonic OSCON 390uF
On power rails: no-name (Chongx) 2200uF 24v (12mm dia x 20mm long fits) this will let me try a higher power supply voltage of 19v.
Spent some time last night listening to it - very very nice combo and fits nicely on the board. Super bass extension and midgrange smoothness and treble clarity with no harshness or sibillance. I just got some DT770-250's for a friend and listened to them for a while. I like the DT880-250's better. The 770's are sealed back and bass reflex (with a small port) - they isolate sound well, but for my ears, sound a tad too bright. Looking at measured curves shows more HF extension and a peak near 10k compared to 880's. If your hearing is soft on the highs, you may like 770's better for their treble enhancement.
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caps trouble
Busy drafting my BOM for ordering, but have trouble deciding on the caps.
Cannot seem to find 2.2uF Wimas (with 5mm pitch) here - will EPCOS do? They're not red.
If I plan to implement this amp as a desktop amp using a 19V PSU, doing duty as both Head Amp (low impedance phones) and Preamp - what would the recommended cap values be? Size is not an issue here.
Busy drafting my BOM for ordering, but have trouble deciding on the caps.
Cannot seem to find 2.2uF Wimas (with 5mm pitch) here - will EPCOS do? They're not red.
If I plan to implement this amp as a desktop amp using a 19V PSU, doing duty as both Head Amp (low impedance phones) and Preamp - what would the recommended cap values be? Size is not an issue here.
Due to miscommunication, this cart had a 16V rail cap on it. Please use the following with a 1000uf 25V rail cap (10mm diameter, 20mm length):
Digikey Cart
Actually, just talked again with XRK. Either may be fine. The two 9V batteries measure slightly over 16V when fresh when loaded, but quickly drop below 16V total.
That's a nice one-stop shopping BOM Sodacose - thanks!
If you want to run the amp in desktop mode with a 19v PSU - I recommend a higher rated rail cap. I found a non-name Chongx 2200uF 24v from Aliexpress that is 13mm x 20mm but can fit perfectly in the tin (see photo of above PCB now fitted into tin). I have not been able to find an equivalent 2200uF cap from a major label. The Chongx, btw, measured better than the Nichicon on my LCR meter with 0.06ohm ESR (10kHz) and 2000uF. Over 3 samples pretty consistent. $1.39 for bag of 10. Will take 3 weeks to get to you though.
https://www.aliexpress.com/item/25V...rs-25-V-2200-UF-size-13-21mm/32741284380.html
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Busy drafting my BOM for ordering, but have trouble deciding on the caps.
Cannot seem to find 2.2uF Wimas (with 5mm pitch) here - will EPCOS do? They're not red.
If I plan to implement this amp as a desktop amp using a 19V PSU, doing duty as both Head Amp (low impedance phones) and Preamp - what would the recommended cap values be? Size is not an issue here.
EPCOS is a fine brand - go for it and don't worry. Vishay, AVX, TDK, are also fine. Just make sure it is a film cap. And for the record, the first hand made PCB prototype used cheap Aliexpress CBB brand MKT's - sounds fine and beat the other amps while costing only $2.50 for a bag of 10.
https://www.aliexpress.com/item/Fre...mm-Metallized-Film-Capacitor/32381386816.html
Most folks like to build amps with the best quality parts at a reasonable price and Wima's have a great reputation (German made and used often in many good projects), but if you build dozens of amps for prototypes, inexpensive no-names get the job done. I am by no means a capacitor snob as most people probably already know. This is my first amp with Elna Silmics (which really are not too expensive).
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The eBay listing ended for the pre-built amp and I can't relist for 30 days since I am a new seller. If anyone wants to order more pre-built amps, I also have an Etsy listing here:
https://www.etsy.com/your/shops/XRKAudio/tools/listings/522023157
https://www.etsy.com/your/shops/XRKAudio/tools/listings/522023157
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