[Whitebread]

Quote:

Originally posted by dokebi Any estimate on when the boards will be available?

I was just about to ask that. Just give me a board, parts list and instructions.

 

[guzzler]

you could make an array of those buffers and attach them to the relevant pads on the PPA board if space allows, remembering however that the PPA is optimised for the HA200x buffers

g

 

[ppl]

Quote:

Originally posted by tangent You could configure a PPA with just one set of op-amp rails, remove all the TLEs, jumper the TLE-G position, tie PS ground to the ground plane and the PS V+ and V- to the appropriate places. That should work. But, to what end? I doubt it'd perform as well, and the premium for the dual supply is likely more than what you saved by removing the TLEs.

Yes Tangent I agree. this would create more problems than it would solve by having all those power supply wires running all around in side the Amp. These is nothing Wrong with the Power supply I used in this Amp.. I would however as stated before would have liked to add cap multipliers on each rail this would add another 30 dB of isolation

Jupiter> I have been working on a discreet buffer that will Plug into the 4 Buffer sockets on each channel. I will prototype sometime next week using Quad Complimentry transistor arrays in the 16 pin dip. these are based upon the now discontinued MPQ-7551. this contains two match pairs of NPN/PNP transistors. I do not like Mosfets or jfets as an output stage since the BJT is a current device domain device and drive low impedance loads real well without the stability problems or high dropout voltages of Mosfets. I am open to sugestions as to the Actual device types so make any sugestions hear. BJT only

it appears that this firm is second sourcing these. this is good as i have used these alot as buffer transistors and thay work great. only 50 MHz. Ft and Hfe of 25 not alot of gain or bandwidth however bandwidth is ok for the AD-8610 multilooped and by using a Dimond buffer the gain will go up. These transistor arrays were intended to drive the Old TTL logic. thay are well matched and sound god if Biased corectly. http://www.centralsemi.com/quads/index.html

 

[guzzler]

would it perhaps be possible to use the Walt Jung discrete buffer as this is a simple design consisting of commonly available parts??

g

 

[ppl]

Have not tried it in the PPA however it sould work fine as long as you can confirm the Buffers bandwidth at at least 70 MHz with the AD-8610 opamp with your intended load

 

[morsel]

We discussed discrete buffers, but are sticking with the HA5002 for the PPA. Discrete class A buffers tend to use a lot of space and power.

There is no ETA on boards. We will let you know when we know.

Read http://elvencraft.com/ppa/ for a basic summary of the PPA.

 

[ppl]

if i get my discreet component buffer to the point that it sounds to me better than a 5002 it will be a plug in module that will fit the 4 5002 sockets so as i can listen to differences and make corrections in addition to finding a way to offer this to Builders of the PPA through tangent if he is interested

 

[morsel]

PPA v0030 layout and schematics are up for viewing at http://elvencraft.com/ppa/

Changes:

Caps are renumbered. C1-->C1, C2-->C2, C3-->C4, C4-->C5, C5-->C7, C6-->C3, new ground channel feedback cap = C6. Sorry for any confusion, but it makes more sense this way.

added opamp rail jumpers for those who wish to use one TLE for all 3 opamps
added wire passthrough slots
moved Alps pot away from edge and mounting holes into corners
removed extra LED current source
moved LED current source to rear of board
removed D2 as the battery board has diodes
added Molex KK 3 pin power header
replaced CRD with a pad that a CRD can be wired to along with an RLED pad to save space
C4 electrolytics are larger in RL than specced, spread them apart so they seat properly
replaced R6G with C6G to suppress a transient 1MHz ring on the ground channel during power on and off
removed R5G
deprecated R3G
removed extra ground pads near the rear inputs as they would be confusing on a soldermasked board
made C4 labels more legible

We are now in polishing mode. Consider the light at the end of the tunnel to be in view. Comments, suggestions, and requests are still welcome.

 

[Whitebread]

*Scratches head in amasement* Excuse my ignorance, but the last time I check this thread, it had 2 pages!! Could some quickly give me a sumation of the advantages of this amp over the META42? And, about this battery board thing, I don't plan on taking any DIY headphone amp anyplace except my desk, so do I have to use the whole battery charger thingy??

(I know what I'm talking about, lol)

 

[morsel]

The battery charger is not required, you can build the PPA as AC only. Advantages over the META42 include better buffers and differential output, which results in better sound. Read the PPA website and this thread for more details.

 

[tangent]

The battery board is indeed optional, but you may still choose to use the battery board for listening at your desk. A NiMH battery pack delivers exceptionally clean power compared to most wall power supplies.

 

[Whitebread]

That would require multiple cells (like you've said) and constant recharging. Even if I used the battery pack, would it be connected to the wall so the batteries would be constantly be recharging?

 

[printed_jim]

What kind of NiMH cells will the PPA be using? Will those be the gumsticks? And how many cells compose the battery pack?

Any estimated battery life yet?

 

[Whitebread]

He said that the battery board was designed for AAA batteries and the charge rate was selected assuming you were using these size batteries. I guess you could mod the board so that it would charge C or even D cell battery packs as I believe he said it could put out over 100mah.

Edit: I believe you can stuff as many as 18 cells in there.

 

[tangent]

Quote:

Even if I used the battery pack, would it be connected to the wall so the batteries would be constantly be recharging?

When the amp is plugged into the wall, the batteries are charging but the amp is running solely from the wall power. If you then unplug the wall supply, the amp runs from the batteries.

Quote:

What kind of NiMH cells will the PPA be using?

AAA's or AA's.

Quote:

how many cells compose the battery pack?

As many as you want, up to 18 AAA's or 10 AA's. (Or more if you chain battery boards together in an external battery pack.) This isn't the time to go into details, but suffice it to say that it will often make sense to go with fewer cells than the maximum the board will accept. The documentation will go into all the gory details to help you figure out what configuration makes the most sense.

Quote:

Any estimated battery life yet?

Depends on the battery configuration and the amp configuration. As a very vague handwaving range, figure 7 to 45 hours, depending on many factors. Again, the docs will cover this when I get around to writing them.

Quote:

I guess you could mod the board so that it would charge C or even D cell battery packs as I believe he said it could put out over 100mah.

I think you need a few more zeros in there....

And no, you wouldn't want to try and mod the board to use large cells. It would be a waste because most of the board would be unused, but you'd still have to pay for it. Instead, a smaller standalone charger board that lets you hook up off-board battery holders would make more sense here. There are no plans to make such a thing at the moment.