Thanks for the kind words ZMan and 
. These are fantastic amps.
X - Got the other boards today. They look fantastic! Waiting on the rest of the parts, then I'll build the temp rig to match components. After I get that done, I'll schedule a day with the guys to build. You've created a product worthy of envy in my circle. I'm glad I ordered extra boards...I think...
. These are fantastic amps. X - Got the other boards today. They look fantastic! Waiting on the rest of the parts, then I'll build the temp rig to match components. After I get that done, I'll schedule a day with the guys to build. You've created a product worthy of envy in my circle. I'm glad I ordered extra boards...I think...
Just wanted to let folks know that the readily available Toshiba 2SK209 can be used if you can’t find BF862’s. I will post the revised resistor setpoints needed. It also depends on GR or BL grade. But we have been using 2SK209’s with the PCA daughterboard for the Aksa Lender preamp main board and also the PCA daughterboard for the Yarra preamp.
This is very good news for future builders, but I bet the BF862's sound better - unobtainiums always sound better.
Hello X my dad has been using the class A hearing aids every day 24x7 and he loves them. I charge them every night. They drop from 16.5v to about 15.4-15.6v in about one day.
My dad can tell the sound quality goes down once it goes below 15v "we tried charging every 2 days but don't sound as good the 2nd day lol".
I'm upgrading his speakers to Knowles RAB-32063-000 Ive heard good reviews on them. I'm going to try to mount them in his old hearing aid cover. Do you know anybody that has worked with balanced armature speakers?
Ive seen some pictures of people with shure shells using them.
Anybody know of where I can get parts?
Thanks
Potatopie
My dad can tell the sound quality goes down once it goes below 15v "we tried charging every 2 days but don't sound as good the 2nd day lol".
I'm upgrading his speakers to Knowles RAB-32063-000 Ive heard good reviews on them. I'm going to try to mount them in his old hearing aid cover. Do you know anybody that has worked with balanced armature speakers?
Ive seen some pictures of people with shure shells using them.
Anybody know of where I can get parts?
Thanks
Potatopie
I use KZ ZX-6 quad driver balanced armature earphones. They have 3 balanced armatures and 1 dynamic driver for bass. Definitely best sounding $40 IEMs anywhere. About 114dB/mW and pair with the PCA very nicely.
My batteries last only 4hrs tops. Get two pairs and swap out when they lose charge.
My batteries last only 4hrs tops. Get two pairs and swap out when they lose charge.
Hi folks, it’s been a while since I have done anything on this thread or amp. I have noticed that there are over 100 views per day for this pocket amp on my Etsy shop. However, hand building them was way too tome consuming for me so I basically stopped offering it as an option. Recently I have gained some experience with having boards fully populated with SMT components by robots in China/HK for reasonable prices. This resulted in the SSR DC protect circuit.
Would there be interest in having this amp fully populated with the SMT parts, minus the through hole parts and mint tin case? I can’t offer matched FETs or anything like that but they would be consecutive parts from a reel so should sound fine.
The populated boards would be fitted with a power JST connector and tested to ensure they work. The user could then install their choice of caps (cap upgrades are your call). The headphone 3.5mm jacks, the volume pot, and the LED. Easy through hole stuff that can be done in an hour. I could do a group buy for a batch at this price if we could get interest.
The price will depend on level of interest but I would say prices will be in the $75 range.
Please add your name, number of boards, and country in the list below:
Would there be interest in having this amp fully populated with the SMT parts, minus the through hole parts and mint tin case? I can’t offer matched FETs or anything like that but they would be consecutive parts from a reel so should sound fine.
The populated boards would be fitted with a power JST connector and tested to ensure they work. The user could then install their choice of caps (cap upgrades are your call). The headphone 3.5mm jacks, the volume pot, and the LED. Easy through hole stuff that can be done in an hour. I could do a group buy for a batch at this price if we could get interest.
The price will depend on level of interest but I would say prices will be in the $75 range.
Please add your name, number of boards, and country in the list below:
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I am also offering the PCA as a Kit with everything needed except the mint tin. Per-orders being taken for $189.
Pocket Class A PCA Headphone Amp Kit SMT prepopulated / | Etsy
Pocket Class A PCA Headphone Amp Kit SMT prepopulated / | Etsy
Very very tempting X! Ironically a friend of mine gave me two Altoids tins last week after returning from a holiday in the States. Altoids you will not find in our part of the world. But the tins are empty.
I must say - my PCA amp is still one of the best (and most satisfying) diy projects I did since I started soldering 3 years ago - even if my amp is not in a mint tin (yet). It looks like a snail without a shell, but boy oh boy - it sounds fantastic!
Very very tempting X! Ironically a friend of mine gave me two Altoids tins last week after returning from a holiday in the States. Altoids you will not find in our part of the world. But the tins are empty.
I must say - my PCA amp is still one of the best (and most satisfying) diy projects I did since I started soldering 3 years ago - even if my amp is not in a mint tin (yet). It looks like a snail without a shell, but boy oh boy - it sounds fantastic!
I still listen to my pca often as well!
Hi Twocents,
You should put it in the tin and let it liberate you as you can move about. I recall you have golden ears and were the only one to successfully identify all of the drivers in the Virtual Blind full range driver thread. The PCA was your prize, and well deserved!
Don't forget the template for the holes for the tin is here:
https://www.diyaudio.com/forums/att...ass-headamp-gb-pocket-class-hole-template-pdf
Use a paper hole punch for the holes for the 3.5mm jacks and the volume pot to start it then use a reamer to enlarge. A regular twist drill just rips the tin.
Btw, the BF862 JFET is EOL and so is the ZVN4306 MOSFET, so I just ran a new simulation using the 2SK209BL ( I know that only GR's seem to be available so I reduced the current to about 5mA to be compatible). I replaced the ZVN with a ZXMN10A08 MOSFET. Both parts seem to have Spice models.
The interesting thing is that it all seems to work with basically the same settings as before with slight change of R3 to 1k1. I am recommending that the output bleed resistor be changed to 1k so that it does not pull down the impedance too much when using lower impedance cans.
Here is revised schematic:
63mA bias at 16.3v and 76mA at 18.2v supply.
Here is predicted THD (0.06%)and FFT (mostly H2 and less H3 and nothing else) for 1Vpp into a 250ohm load:
I am going to have to test it out - but looks like it can all work.
You should put it in the tin and let it liberate you as you can move about. I recall you have golden ears and were the only one to successfully identify all of the drivers in the Virtual Blind full range driver thread. The PCA was your prize, and well deserved!
Don't forget the template for the holes for the tin is here:
https://www.diyaudio.com/forums/att...ass-headamp-gb-pocket-class-hole-template-pdf
Use a paper hole punch for the holes for the 3.5mm jacks and the volume pot to start it then use a reamer to enlarge. A regular twist drill just rips the tin.
Btw, the BF862 JFET is EOL and so is the ZVN4306 MOSFET, so I just ran a new simulation using the 2SK209BL ( I know that only GR's seem to be available so I reduced the current to about 5mA to be compatible). I replaced the ZVN with a ZXMN10A08 MOSFET. Both parts seem to have Spice models.
The interesting thing is that it all seems to work with basically the same settings as before with slight change of R3 to 1k1. I am recommending that the output bleed resistor be changed to 1k so that it does not pull down the impedance too much when using lower impedance cans.
Here is revised schematic:
63mA bias at 16.3v and 76mA at 18.2v supply.
Here is predicted THD (0.06%)and FFT (mostly H2 and less H3 and nothing else) for 1Vpp into a 250ohm load:
I am going to have to test it out - but looks like it can all work.
Attachments
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Just a crazy idea for the future...
What about a Ready to Run (RTR) fully assembled PCA Mk II with integrated LiPo battery charging (via micro USB) and management system, DC-DC step up, capacitance multiplier soft start, and STL files for making your own 3d printed case? Or use same mint tin if desired.
JPS64 has been busy again...
What about a Ready to Run (RTR) fully assembled PCA Mk II with integrated LiPo battery charging (via micro USB) and management system, DC-DC step up, capacitance multiplier soft start, and STL files for making your own 3d printed case? Or use same mint tin if desired.
JPS64 has been busy again...
Attachments
More progress from JPS64. The amp will have a 4100mAhr LiPo battery. It will for either the 3D printed case (will provide STL file) or the traditional Altoids tin.
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