[stormlifter]

Okay well I wrote this 2 times

the forum died... oh well...

I'm want to make a Meta42 Headphone AMP, but I want it to be differant. I know you guys know a **** load of stuff and I wanted to run some of my ideas and questions through you...

*=- First off, I'm not too sure about the parts and stuff... I've been tohttp://www.tangentsoft.net/audio/meta42/parts.html and I've looked over most of that and understand most of it... I'm rather new to this whole AMP thing but I'm patient and willing to learn and spend tons of time. Throughout this post I hope you can begin to understand what I'm looking for in an AMP and be able to offer some opinions and advice as what I should do....

*=- I'm wanting to make a Portable AMP that can also draw power from a wall jack. I've got ideas for having it recharge the batteries while it's plugged in... I'd like to know some things about having like 2-5 9volt (or other) battiers tied in together inside the amp to power it and then when it is plugged in to recharge them... but i'm not sure how that would work... you all help.

*=- Question : Can i have like 3 outputs (assorted types) and will that effect the power of the output if I only have 1 plugged in at the time ? or will it only start to loose power when I plug something into the jack ? I'm planning on having like 2-5 3.5mm jacks for when others want to listen in... and then having a 1/4'' and a Component jack for listening to DVD's and other stuff...

*=- Buffers : Well if I can get all those batteries to work... I probably could get like 3 EL2001's stacked without to much problems... or anything else you guys think it would work with about 5- 9volt batteries or other...

<EDIT> - ADDED )*=- Hardware to build : What type of hardware am I going to need ?? What type of soldering iron do you suggest ?? and other things ?

I've got this idea about having the AMP change to more current drawing Buffers when it's plugged in... not sure if this is possible though, I was thinking having a switch that I could use to turn it to the higher power eating buffers when I plug my amp in...

I would probably need to regulate the power stuff really well... I 'm not sure about all that, Maybe just the same.

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Thanks ahead of time for your amazing help and be waiting for my post on when I get it done... I'll have some Pics and a guide if I think it's good enough !...

-stormlifter the Keeper of the Peace
"peace to the sTorMs of your mind....

 

[ppl]

I will only comment on the the batteries and Buffer issure. 9 volt batteries are not designed to be consistently charged and will become bad in a few mo. if do so. Use 16 AAA,s or AA these cells are designed for continious carging. a battery management IC like the MAX-712 is great for this type of Virtual Battery power.

If using tangents Board the EL-2001 or EL-2002 is the Buffers that will fit that board. I like a stack of (4) el-2001's or at least (2) and perfer (4) el2002. you can get a stack of (4) using a AD-8620 opamp and (4) EL-2001's the amp will draw about 20 mA. with a stack of (4) el2002 it will draw about 50 mA. However I like the mids and Highs better with the EL-2002.

 

[stormlifter]

Would that many buffers work with the batteries ?? how could I check the buffer to - battery ratio ?

 

[CaptBubba]

I would reccomend that you build something other than the final amp first, just to get the hang of soldering and placing parts. One cold solder joint could potentially make a $300 amp sound like a $30 one.

To get an idea for how long the amp will run, take the current draw per channel of the buffers, double it, add about 10mA fr the opamp, and then divide the battery capacity by that number. That's the max runtime (in hours) that you will get, really you will be looking at ~50% of that.

So, the actual runtime would be (using 1700mAh AAs):

2x2001= 28hrs
4x2001= 17hrs
4x2002= 7.7hrs

Using 9V batteries (200mAh):
2x2001= 3.3hrs
4x2001= 3hrs
4x2002= 1.5hrs

These are aproximite numbers of course. If you listen to music at loud volumes, time will go down, if you listen at low volumes time will go up.

 

[Gariver]

Hi ppl:

The MAX-712 is a fast charging system for batteries. Is this what you are talking about?

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1666

Why is it so hot?

 

[stormlifter]

Wow man... Thanks Gariver.. thats sweet thing... i'll have to read more about it... anyone else used this thing that he's talkinga bout ? think it would work with a portable Meta42 ?? wow ! ! that would be sweet... and 16 batteries is enough to run with 4x EL2002's for about 5 hours.. ! ! perfect ! ! and I'm still working on a way to have the AMP switch to EL2001's if I want it, maybe have a few switches for more battery life...

Keep 'em coming everything thus far has been helpfull... please keep it up

 

[CaptBubba]

That was actually a conservative estimate, I had already divided the max runtime in half to get that number.

 

[ppl]

The advantage of the MAX-712 is it will do up to 16 series connected cells vs 10 that other IC's will do. The schematic on the first page with the added cascode transistor showen within the data sheet. sory can't remember the page but look under high cell count or full 16 cell somthing along that. also search since this is an old thred that has been around for a few years.

 

[Gariver]

Thanks ppl! Boy, these people over at Maxim-IC have done a lot of work on batteries. It's really amazing! The link below is simply loaded with solutions. It will take me a while to digest this stuff. Take a look...

http://www.maxim-ic.com/PowerSupplies.cfm

Hey, Stormlifter! I'm glad you liked the previous link! Good luck to you!

 

[damonpip]

Yea, there's lots of sweet battery management ICs out there. I'm planning on making a smaller sized Meta that will run on two Li-Ion batteries. Linear Technologies makes many Li-Ion charinging ICs, they may make some for Ni-Cads too.

 

[stormlifter]

Well thats awesome info guys... I'm going to need to start a list of parts I need to get... could someone give me a hand ?? I want to deck it out... I can understand about buffers and stuff like that but the other parts that I need mystify me... I get the jacks and stuff though, I want to have like 4x 3.5mm and 1x of the 1/4's... and then a pair of right left composite plugs... I understand that bit... I have the list from Tangents but I know there has to be more...

Thanks so much for the help thus far ! I'll be sure to let you know how the project progresses...

stormlifter the Keeper of the Peace