What are the bassis of this comment:
- How many have built this amp?
- How many who built this amp also have the best commercial offerings?
- How many who have built this amp, and has the best commercial offerings, expressed that it can beat the best commercial offerings?
xrk has created half a dozen threads about the headamps he built, advocating how good his amps are, and attracted the resonance of a few. That's OK, as long as it stays DIY, but when it turns into a commercial operation, then it's good for the potential customers to be reminded of what they're buying into, and whether it's fair value - so the price does matter. It's nice that we have someone like needtubes, who took the risk to be the unwelcomed whistleblower
Moderator: I'm wondering if this thread should be moved to the Vendor's Bazaar, it's full of eBay (and etsy) advertisement in the last two pages.
Weitan,
The fact remains that I still provide the PCBs at a reasonable cost typical of most group buys. People are welcome to build it for a minimum cost of parts and their labor. Anyone not interested in a prebuilt unit is welcome not to buy it prebuilt. As far as the sound quality - the Pocket Class A was one of two amps in the Blind Virtual audition thread that got a statistically high number of votes. How many people have built it? At least 6 that I can count, but there are over 100 boards are out there right now in various stages of build but some folks don't report back whether or not they build it. The amp is currently being reviewed by Headfonics.com. For the record, they contacted me about providing a review sample based on user recommendations.
To thank Needtubes for being a "whistleblower"? That would imply that he was calling out some illicit activity that needed to be brought to attention? Yes, we all need to be protected from unscrupulous forum members offering to sell prebuilt amps for more than the cost of the amp.
The fact remains that I still provide the PCBs at a reasonable cost typical of most group buys. People are welcome to build it for a minimum cost of parts and their labor. Anyone not interested in a prebuilt unit is welcome not to buy it prebuilt. As far as the sound quality - the Pocket Class A was one of two amps in the Blind Virtual audition thread that got a statistically high number of votes. How many people have built it? At least 6 that I can count, but there are over 100 boards are out there right now in various stages of build but some folks don't report back whether or not they build it. The amp is currently being reviewed by Headfonics.com. For the record, they contacted me about providing a review sample based on user recommendations.
To thank Needtubes for being a "whistleblower"? That would imply that he was calling out some illicit activity that needed to be brought to attention? Yes, we all need to be protected from unscrupulous forum members offering to sell prebuilt amps for more than the cost of the amp.
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Nice! I'm buiding a desktop version with 16 V feed, but I coud crank it up to 18-19 V very easily if I change the rail caps to 25 V version. Any easy and effective ways to improve cooling? I was thinking of some kind of aluminum bar connected to the larger fets.
I would remind you that your misguided questions should be aimed to XRK, not to Prasi, who had layout control - no more, no more. Why should you consider the moral ground; perhaps this is tall poppy behaviour. What is to you? Will you buy one? Do you regard others who do decide to purchase that they are idiots, and have no judgement?
The entire carriage of this product has been laid bare by XRK on this forum. Only the pcbs are offered to the group buy; the full products are offered elsewhere. All the protagonists are all out in the open, including me. Why is it inevitable that someone with drive, determination, intellect and energy, who puts up something fully described through all the detail posts, and then offers a pcb for peanuts, and then further decides to sell full plug 'n play product through commercial channels attracts so much enmity?
Anyone - anywhere - anytime - takes a risk to produce any product. The R&D always precedes the sale of any product, and a lot of time and effort and money is invested in this, and related, products. I know more than most; I do the same thing, and have been involved in freebie for forum members on the FetZilla, for example. I have even sold the pcbs for profit - yet never attracted any criticism.
Why for XRK?
I'll tell you what, Weitian, why don't you offer something here on this forum, start out with cheap pcbs, and see how you go? Or, is it true that you have an interest in selling electronics yourself? Whistleblower, I have never seen anything so ridiculous......... keyboard cowboys stuff. Pay the peanuts for the pcb, build yourself, and then know for yourself. And bear in mind that Prasi should not be criticised either. You might post to Ebay and tell them they are doing a terrible, immoral act selling HPA. What about all the other product there that is five times more expensive? Do I hear you criticise them too?
This should be the end of the matter.
Hugh
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There is a thick silicone heat sink spacer sheet material (blue color used for CPUs) that is conformal. Cut a piece to cover the MOSFETs and the resistor arrays and the copper pads on the Drain of the MOSFETs. Clamp a small aluminum heatsink with fins to it somehow.
Use this pad:
http://m.ebay.com/itm/131319336180?
Cut this down:
http://m.ebay.com/itm/5pcs-x-100-25...ip-for-IC-LED-Power-Transistor-/171070417214?
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To credit the right person, it's BDHM who made the layout. prasi is the one who expressed the statement "most will agree that xrk has created a piece of equipment that can beat the best commercial offerings" though.
I asked questions on statistical facts, and it seems you don't like factual questions. Let's see what judgemental words you've used in your post: "misguided", "tall poppy behaviour", "ridiculous", "keyboard cowboys"
Would you kindly not to put words into my mouth, please.
At long last, we have an agreement on this. Indeed I also think this is a commercial product development, which is why I suggested to move it to the Vendor's forum. Apart from raising the questions on some statistics, did I say anything bad about the product in my post?
It amuses me everytime you jump to xrk's defense, xrk is certainly man enough to defend himself. While he didn't give all the statistics I asked for, in post #522 he's calmly provided info about the virtual audition and the review by Headfonics.com, providing ground for rational reasoning, instead of launching negative words for a meaningless fight.
Another thing we agreed. My intention is to offer my viewpoint and support to needtubes, once and for all, after that it's people own judgement if they want to buy this product. Your post compelled me to reply another time, I hope I won't need to make another post in this thread.
^^Thanks X!
The thermal compound is a great idea, just ordered some. I think I'll try to connect the FETs to my chassis' aluminum bottom plate and if that's a no go I'll get the heat sinks too. See below my build. Most of the space is covered by LDR volume control board.
The thermal compound is a great idea, just ordered some. I think I'll try to connect the FETs to my chassis' aluminum bottom plate and if that's a no go I'll get the heat sinks too. See below my build. Most of the space is covered by LDR volume control board.
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That will work very well for a desktop amp. Simply clamp board to chassis plate with squishy thermal pad. Wish I put M3 screw holes on the board LOL
You can also use a clamp bar across 3.5mm jacks which seem very sturdy.
What's the you are using for a PSU? Looks like it had an IC?
You may need to double up thickness of pad to prevent certain pins from touching. Chassis since they are sharp and poke through silicone. Maybe add layer of Kapton tape on chassis underneath silicone to be safe. That silicone works real well. I use it for some class A MOSFETs dissipating 30 watts no problem.
You can also use a clamp bar across 3.5mm jacks which seem very sturdy.
What's the you are using for a PSU? Looks like it had an IC?
You may need to double up thickness of pad to prevent certain pins from touching. Chassis since they are sharp and poke through silicone. Maybe add layer of Kapton tape on chassis underneath silicone to be safe. That silicone works real well. I use it for some class A MOSFETs dissipating 30 watts no problem.
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Weitian,
You made a statement that last 2 pages are full of ebay and etsy ads, pl go and read again, one post is informing the ebay listing and another post is informing that ebay listing has ended due to its new member rules and its been moved to esty. do you call this as two pages (20posts) of ads? wow!
If you will read my post again and try to think what I am trying to convey, you would realize that its the time, effort and R&D of a single person that has built the amp that makes its special and he has the right to keep the price that he considers as rewarding for his individual efforts. Same goes for needtubes, you and everyone else, everyone's time and effort is valuable and its that individual's discretion on what monetary value he puts to it.
Everyone who has read the thread or cared to read post No.1 (I suggest you do that) and few posts following(post no.45), can immediately come to know what would be the price of buying a PCB and components (from a linked digikey cart) and building it themselves, so the "whistle blowing" comment is rather uncalled for and "some might" even consider it as bordering more on trolling than being helpful in this context..
reg
Prasi
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I feel obliged to post again since everyone keeps including my name in their comments...
I appreciate that xrk responded mostly kindly to weitian in post 522, however it feels like both xrk and prasi were somewhat less than kind toward me in posts 509 and 510, respectively. That's fine, but please refrain from putting words in my mouth. Seems everyone is taking this very personally and inferring some insult toward the product itself when none is intended. It seems to be a fine amp and is a nice looking product. It isn't my thing, though, for two reasons: I have a nice digital audio player for portable use which includes a fine amp section, and if I listen to headphones at home, I already have an assortment of nice wall-powered amps from which to choose (and more designs in the queue...).
My initial post (#508) was made after a long week, and I was tired. Seeing the phrase "special price" rubbed me the wrong way since the price seemed quite high. My other comments about credit are likely attributable to the "snapshot" way in which the forum posts documenting the project appear. Reading many of the development posts makes it appear to me as though a large portion of the design work is attributable to others. Again, this is just how it reads to me at times, and is likely due to the fact that we only get snapshots over time. Each can draw one's own conclusion, and no one but those involved really know how development proceeded. No disrespect intended, so please don't take offense. I see no point in discussing the matter, as it will only lead to further conflict. And it just isn't worth it to me to have my experience on the forums marred with conflict...
Finally, I would like to let the record reflect that after xrk and prasi replied to my post, I contacted moderation to have all three posts remove since they were off-topic and would likely generate further conflict. However, moderation did not comply or respond... And so we find ourselves arguing still.
I appreciate that xrk responded mostly kindly to weitian in post 522, however it feels like both xrk and prasi were somewhat less than kind toward me in posts 509 and 510, respectively. That's fine, but please refrain from putting words in my mouth. Seems everyone is taking this very personally and inferring some insult toward the product itself when none is intended. It seems to be a fine amp and is a nice looking product. It isn't my thing, though, for two reasons: I have a nice digital audio player for portable use which includes a fine amp section, and if I listen to headphones at home, I already have an assortment of nice wall-powered amps from which to choose (and more designs in the queue...).
My initial post (#508) was made after a long week, and I was tired. Seeing the phrase "special price" rubbed me the wrong way since the price seemed quite high. My other comments about credit are likely attributable to the "snapshot" way in which the forum posts documenting the project appear. Reading many of the development posts makes it appear to me as though a large portion of the design work is attributable to others. Again, this is just how it reads to me at times, and is likely due to the fact that we only get snapshots over time. Each can draw one's own conclusion, and no one but those involved really know how development proceeded. No disrespect intended, so please don't take offense. I see no point in discussing the matter, as it will only lead to further conflict. And it just isn't worth it to me to have my experience on the forums marred with conflict...
Finally, I would like to let the record reflect that after xrk and prasi replied to my post, I contacted moderation to have all three posts remove since they were off-topic and would likely generate further conflict. However, moderation did not comply or respond... And so we find ourselves arguing still.
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Personally, I think that one of the greatest things about this project is the fact that several people have collaborated to bring this amp to fruition. I watched the development thread during that phase, and I was pretty amazed to see what amounted to a crowd-sourced R&D effort built on goodwill and camaraderie. I'm grateful to all of the contributors. You folks have an obvious and contagious passion for this hobby.
Wish I put M3 screw holes on the board LOL
You can also use a clamp bar across 3.5mm jacks which seem very sturdy.
I am also thinking on how to mount this board for a desktop amp. It seems there is a growing need for a desktop version of this board.
These look like just the ticket. I just want to double check with you before ordering these. The listing says that the size is 13x21mm and the brand is something different in the photo...says Chenbin or something. So is this link indeed the correct listing? Thanks.
It's probably fine but if you want the actual ones I got, it's from this shop - a bag of 50, so more than you need but look around, maybe they have smaller quantities.
https://www.aliexpress.com/item/Fre...minum-Electrolytic-Capacitor/32677236564.html
I am also thinking on how to mount this board for a desktop amp. It seems there is a growing need for a desktop version of this board.
I am developing a true high power SE Class A desktop amp now - maybe a few months away from production but we are talking 4w into 50ohm load or 10w into 8ohm load. 3 transistors in audio path. About 60 to 70w dissipation per channel. Maybe too much heat for most people.
I am also working on a larger desktop version of current pocket amp with 100mA bias so should handle 50ohm cans better.
I have built three of the four boards that I have received. All use the 2200uF/16V rail
cap's, and the stock Wima 2.2uF at C1. The first two use unmatched MOSFETs, the
third, and eventually fourth, have a matched set from X, and are from the second
group buy.
The first uses 100uF/25V Silmics/Wima 1uF at C2. (I used the 25V Silmics because I already had them on hand.) Bias is 57.5/59 mA using 33R at R4.
The second one is completely stock (except for the rail cap's). Bias is 58/59 mA using
47R at R4 (33R produced only 49 mA).
The third uses OSCON 1000uF/16V at C2, with Wima 6.8uF as bypass. Bias on this one
is 58/58mA with 33R at R4 (can you tell that it uses the matched MOSFETs?)
I've also tried the Nichi UKA 47uF/Wima 1uF combo as well.
I don't have any good low impedance 'phones, using only my HD800's. I may pick up
a pair of the Massdrop Fostex Th-X00's, which have an impedance of 25 ohms, to try.
So far, my preference at C2 are the Silmics. To me, the sound is more involved with better spatial imaging, and not quite as aggressive as the OSCONs.
I still stand by my earlier observation that this amp scales quite well with better
'phones/sources. It's just a matter of futzing with cap's and bias to match your 'phones.
cap's, and the stock Wima 2.2uF at C1. The first two use unmatched MOSFETs, the
third, and eventually fourth, have a matched set from X, and are from the second
group buy.
The first uses 100uF/25V Silmics/Wima 1uF at C2. (I used the 25V Silmics because I already had them on hand.) Bias is 57.5/59 mA using 33R at R4.
The second one is completely stock (except for the rail cap's). Bias is 58/59 mA using
47R at R4 (33R produced only 49 mA).
The third uses OSCON 1000uF/16V at C2, with Wima 6.8uF as bypass. Bias on this one
is 58/58mA with 33R at R4 (can you tell that it uses the matched MOSFETs?)
I've also tried the Nichi UKA 47uF/Wima 1uF combo as well.
I don't have any good low impedance 'phones, using only my HD800's. I may pick up
a pair of the Massdrop Fostex Th-X00's, which have an impedance of 25 ohms, to try.
So far, my preference at C2 are the Silmics. To me, the sound is more involved with better spatial imaging, and not quite as aggressive as the OSCONs.
I still stand by my earlier observation that this amp scales quite well with better
'phones/sources. It's just a matter of futzing with cap's and bias to match your 'phones.
Thanks for the update Funch. I wonder if it's because my DT880's are kind of laid back on the top end that I don't find oscons harsh? When using DT770's things were definitely more forward. Maybe I will try a no oscon but Silmic amp to see if that tames the in my face DT770 sound. I think there is a big peak at 10k and it extends quite a bit higher for treble.
Hey Funch,
Glad you've had three successes. I may try the 33R at R4 in my second board as you did, just to get that extra bit of bias current. I haven't heard the Silmics (I'd try them, but I have 50 Ohm Sennheisers) but anyway I thought the OSCONs were pretty smooth and the Nichicons more transparent. What did you think of the 470uF Nichicons? I used the 25V version. Speaking of which, you probably came out ahead using 25V Silmic caps on the output. I've been reading up on caps and have been trying to assimilate Cyril Bateman's work--even geeking out and graphing some of his data. A 25V rated cap with a 6.5V bias is close to the sweet spot for low distortion. Good to know that the 6.8uF WIMA fits in there too!
Glad you've had three successes. I may try the 33R at R4 in my second board as you did, just to get that extra bit of bias current. I haven't heard the Silmics (I'd try them, but I have 50 Ohm Sennheisers) but anyway I thought the OSCONs were pretty smooth and the Nichicons more transparent. What did you think of the 470uF Nichicons? I used the 25V version. Speaking of which, you probably came out ahead using 25V Silmic caps on the output. I've been reading up on caps and have been trying to assimilate Cyril Bateman's work--even geeking out and graphing some of his data. A 25V rated cap with a 6.5V bias is close to the sweet spot for low distortion. Good to know that the 6.8uF WIMA fits in there too!
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