[Avro_Arrow]

 
OK, when I have free time I will start laying out the board.

I'll keep everyone updated

 

[backspace119]

If I could help in any way I would but I am very inexperienced. I have a HUGE interest in things like this and I was just about to try to build a PPA v2 from tangent's site....I'm guessing now that this amp is rather out dated and there are better options out there....Honestly if there could be 2 designs for this (one designed completely for space considerations and one made for quality considerations) that would be incredible.
 
P.S. I would really like to get into this stuff if anyone here would mind giving me a bit of help in this. I have some experience with circuit building and none with designing (Although I understand how a lot of things work and I am a quick study) The only amp I've built so far is a CMoy that I managed to add bass boost to (with my own design) but I would /love/ to get into real design.

 

[Avro_Arrow]

  If I could help in any way I would but I am very inexperienced.

When it comes time to build one of the prototypes, put your name in...

 

[Avro_Arrow]

  I have a HUGE interest in things like this and I was just about to try to build a PPA v2 from tangent's site....I'm guessing now that this amp is rather out dated and there are better options out there....

I wouldn't say the design is outdated.
The only thing I would do differently, is if it
were to be a desk amp and not portable, I
would use a dual rail power supply and
either balance or single ended...but not
three channels.
The three channel amp is a compromise
for the sake of using batteries. I know there
is the option of center tapping the battery pack,
but that has it's own set of drawbacks...

 

[vixr]

   
OK, when I have free time I will start laying out the board.
 
I'll keep everyone updated

 

[backspace119]

 
When it comes time to build one of the prototypes, put your name in...

I would love to. I'm a bit strapped for cash but if the components are within the 100-200$ range I could possibly fork out enough to get by.....the money going to the PPA v2 is still going to it or a version of it so I'm fairly certain I won't have it when it comes time to build this.

 

[backspace119]

 
I wouldn't say the design is outdated.
The only thing I would do differently, is if it
were to be a desk amp and not portable, I
would use a dual rail power supply and
either balance or single ended...but not
three channels.
The three channel amp is a compromise
for the sake of using batteries. I know there
is the option of center tapping the battery pack,
but that has it's own set of drawbacks...

That would help a lot with costs because the PCB for the batt pack is expensive (if bought from ExpressPCB) do you have a link for a good dual railed PSU? would this require heavy modification to the amps design or no? (I haven't reviewed the design just yet because I'm not able to order parts just yet (I'm still in high school and without a job so I only occasionally have cash)) Thanks in advance.
 
P.S. As far as quality goes what is the best DIY headphone amp? the PPA? or would this "Trident" be better? (again i'm inexperienced and I understand a bit about the circuitry and such but I don't have enough experience to really know whats best....)

 

[backspace119]

I'll still help any way I can. thanks for linking me here I think I have an idea of what to do now.

 

[scootsit]

 
I have a HUGE interest in things like this and I was just about to try to build a PPA v2 from tangent's site....I'm guessing now that this amp is rather out dated and there are better options out there....

I wouldn't say the design is outdated.
The only thing I would do differently, is if it
were to be a desk amp and not portable, I
would use a dual rail power supply and
either balance or single ended...but not
three channels.
The three channel amp is a compromise
for the sake of using batteries. I know there
is the option of center tapping the battery pack,
but that has it's own set of drawbacks...

I recently heard that someone (likely many) were releasing NiMH batteries that had higher charge densities than lithiums at a third the price, and with faster charge cycles, supposedly coming out this year. It might be something to consider.

 

[wakibaki]

I recently heard that someone (likely many) were releasing NiMH batteries that had higher charge densities than lithiums at a third the price, and with faster charge cycles, supposedly coming out this year. It might be something to consider.

 
It would be nice. Have you got a link? It doesn't sound very likely to me.

 

[scootsit]

I recently heard that someone (likely many) were releasing NiMH batteries that had higher charge densities than lithiums at a third the price, and with faster charge cycles, supposedly coming out this year. It might be something to consider.

It would be nice. Have you got a link? It doesn't sound very likely to me.

This is the last sentence of the NiMH wiki. "In October 2009, ECD Ovonics announced that their next-generation NiMH batteries will provide specific energy and power that are comparable to those of lithium ion batteries at a cost that is significantly lower than the cost of lithium ion batteries.[31]"

The company made most of the batteries for hybrid cars. It looks like they went out of business in 2012, selling to BASF, who licenses the technology. I'm assuming they're in production, I just haven't found them yet. I am finding pp3 NiMH batteries with upwards of 300mAh, but not quite the 600mAh oh lithium ion.

 

[scootsit]

Not much different price wise than lithium, but it would mean a simpler charger.

I found these at 500mAh: http://m.ebay.com/itm?itemId=151214530672

And these at 450: http://m.ebay.com/itm/400657400342?nav=VI

 

[wakibaki]

First link doesn't work.
 
Interesting, 450, that's quite a lot more than the 200mA Uniross I've got, but Chinese-sourced batteries often claim more capacity than they have in practice. Unfortunately I don't have a lithium 9V battery, and I can't find any rechargeables on the internet. It's a bit more complicated to make comparisons for single cells since a lithium AA with 3.6V 2000mAh would have 3 times the energy density of a NiMh AA @ 1.2V 2000mAh. It's quite obvious, however, that a 1.2V NiMh AA would require 6000mAh just to equal a 3.6V 2000mAh lithium AA.
 
Just equal energy density, cheaper and with less charging problems would be good, though.
 
w

 

[scootsit]

  First link doesn't work.
 
Interesting, 450, that's quite a lot more than the 200mA Uniross I've got, but Chinese-sourced batteries often claim more capacity than they have in practice. Unfortunately I don't have a lithium 9V battery, and I can't find any rechargeables on the internet. It's a bit more complicated to make comparisons for single cells since a lithium AA with 3.6V 2000mAh would have 3 times the energy density of a NiMh AA @ 1.2V 2000mAh. It's quite obvious, however, that a 1.2V NiMh AA would require 6000mAh just to equal a 3.6V 2000mAh lithium AA.
 
Just equal energy density, cheaper and with less charging problems would be good, though.
 
w

I posted from my phone. If you put the item number in, it still works. Nevertheless, it's a company called LiteLong, here's another auction for the same basic item: http://www.ebay.com/itm/161219678869

Interestingly, if you google LiteLong, you will find that they actually have Lithium Ion batteries rated up to 880mAh, which, if true is nearly an alkaline!

I still like the idea of using a qi pad to charge, it would allow for a smaller case. The pads are  ~$5 and only about 1/8" thick, as I understand it. Soldering could be a tad tricky, but it might be possible to stick it onto a board with smt pads on the bottom for power. Here's one for a Samsung, there is a standard implementation of lead spacing, too: http://www.amazon.com/Samsung-Standard-Wireless-Charging-Receiver/dp/B00BCC2B1Q/ref=pd_sim_cps_2

 

[wakibaki]

Thanks for that.
 
I found a few people who had tried these high-cap batteries. They were doing comparative tests, so what impressed them, impressed me.
 
Also the qi pad was new to me, this is a possibility for a design, but there are some outstanding problems that, IMO, mean that the absolute performance will not equal that of designs with an offboard transformer. 
 
w