[mminutel]

Well guys, I love DIY now thanks to all of you and want to build a PIMETA to use as a stationary computer type amp. I have a couple of questions if you don't mind. Notice that it will be run strictly off of DC until I decide that I need it as my portable.

1. Do I need to build the TREAD as well? If so, why? I know that it is for power but what is it needed for?

2. Which case do you recommend?

3. 1/8" input jacks or RCA input? Why?

4. Is there a great difference in sound over the CMOY?

5. To stack the buffers or not to stack the buffers?

6. Do I need to use the crossfeed?

7. Is there a way to make it powered by batteries and or wall wart? I would sort of like to make this my portable if I feel like it. It won't be at first but I would like the option to be available, it not then no worries. Ill just build two

8. Anything else that I should know?

Also, I will have more questions as time permits, that I am sure of. TIA!

 

[MisterX]

1) No. Power regulation
2) This is DIY.... figure that part out for yourself.

3) RCA, durability.
4) Yes.
5) Stack them.
6) No.
7) Of course there is.

 

[mminutel]

Thanks. I have read almost everything on Tangent's site but I still don't quite understand what the crossfeed is for. If it is good to have then I will use it.

 

[MisterX]

Have you read CMoy's headwize article about crossfeed as well?

http://headwize.com/projects/showfil...=cmoy1_prj.htm

 

[MASantos]

1. Do I need to build the TREAD as well? If so, why? I know that it is for power but what is it needed for?

The tread regulates the power coming out of the transformer( internal or external). You can use an unregulated power supply, but IMO a tread or steps is one of the best things you can add to pimeta. If you don't want to build one you can also get an elpac PS which is regulated, but if you check tangents power supply comparison, you'll want to use a tread.

2. Which case do you recommend?
It really depends on your budget and preferences. Usual choices are hammonds extruded aluminium 1455 series.

3. 1/8" input jacks or RCA input? Why?
You will probably want to go with RCA. As MisterX said, they're more durable. The great thing about DIY is that you can do it as you want, so you can have rca and 1/8 at the same time.

4. Is there a great difference in sound over the CMOY?
IMO, yes. There is a vey big diference.

5. To stack the buffers or not to stack the buffers?
I my pimeta I stacked only the buffers on the L/R channels. I stacked ground but I didn't hear any difference so I just went back to a single ground buffer.

6. Do I need to use the crossfeed?
You don't need to use it. Crossfeed puts a bit of the left channel sound in the right channel and vice versa. This way you get a sound which is more similar to speakers. Some people like it some don't. This is something you can add later down the road.

7. Is there a way to make it powered by batteries and or wall wart?

The easiest way would be to throw a couple of 9v battery straps and be done with it. You can also add a simple trickle charger and save some money on batteries. (search for trickle charger and a thread should come up created by member tomb. He has a good photo guide to build one.)



Hope it helps. When you finish it, post some pictures in the gallery!

Manuel

 

[Calroth]

To answer question 2 specifically, one thing you should do is browse the "Post pics of your builds" thread - it's stickied to the top of this forum. You'll find plenty of PIMETAs (amongst other things). Find one that looks good... there's usually commentary on what the enclosure is and where to get it. If not, you can ask!

 

[rb67]

Quote:

Originally Posted by mminutel /img/forum/go_quote.gif Thanks. I have read almost everything on Tangent's site but I still don't quite understand what the crossfeed is for. If it is good to have then I will use it.

Crossfeed changes the soundstage of the headphone. My closest description would be it makes it sound as if you are listening to speakers. That is the sound is placed in front of you instead inside your head. If you were to close your eyes it would sound like there are speakers there. If you use foobar2000, you can download a dolby headphone plugin that lets you experience this. It is quite creepy.

 

[ferencvaros]

I built my second pimeta with soic opamps and buffers, I soldered them directly on the bottom side of the board.Now I would like to try buffer stacking..
Would it be possible to stack soic and dip buffers together ???

 

[MisterX]

Quote:

Would it be possible to stack soic and dip buffers together ???

You sure can.

 

[mminutel]

Alright, thanks everyone. I had looked at the DIY projects, that is actually what turned me on to the PIMETA. The PPA looks awesome but I don't think I can tackle it yet, and the Millet looks a little expensive if I mess it up. I have up to $100 possibly $150 because I have some Visa gift cards lying around so if money permits I will get the TREAD as well.

MASantos: I saw your PIMETA and liked it really well, especially the switchable input jacks. I think i'm going to snag the case that you have. The only thing that I was worried about is not being able to fit everything because I am not sure of the exact dimensions of it all.

Thanks again for all of the posts. I think ill add RCA up close to the top so I can add a 1/8" later on.

 

[ferencvaros]

I built Pimeta, Millett, Soha and CK2III...
In my opinion is easiest Millett and most complicated Pimeta.
On the Millett PCB you have enough place, board is big enough. If you do some mistake it is very simple to repair it. Instead of BUF634 you can use OPA551, which is easier to find and for me also cheaper.
Pimeta's PCB is smaller and every mistake cost repair lot of effort (They are for sure other more hard to build project like AlienDAC). Also good opamps costs lot of money.

I started my DIY journey with Pimeta, but now I would definitely start with Millett, which sounds better to my ears than Pimeta (but it is very subjective).

 

[mminutel]

unfortunately the millet is a little out of my price range. i only have about 100$ to spend because i am picking up a sound card amongh other things.

when i make the TREAD, does the mA of the wall wart matter much? Also, do wallwarts come with their own input jack because I don't see one on the parts list.

 

[FallenAngel]

You might be hard pressed to build a pimeta within 100, but it's doable.

The mA rating of the wallwart does matter, just make sure it's enough to power your amp. For Pimeta, there's very little current draw, even like a 100mA would be enough, but might as well go for something like a 400mA to be able to use it for other amps later.

No, wallwarts don't come with their own input jacks, they have prongs to plug into the wall and an output plug (stardard sizes are 2.1mm and 2.5mm). You will need to buy a DC power jack of the same size to plug the wallwart into.

 

[tomb]

Quote:

Originally Posted by mminutel /img/forum/go_quote.gif unfortunately the millet is a little out of my price range. i only have about 100$ to spend because i am picking up a sound card amongh other things. when i make the TREAD, does the mA of the wall wart matter much? Also, do wallwarts come with their own input jack because I don't see one on the parts list.

500 ma is a good round number, although the PIMETA won't use all of it. The nice thing is that if you build the TREAD separately, you can use it for the Millett, the PPA, and the M3 - among others. That 500ma will handle them all. A simple way to do this is to make a dongle out of the TREAD and a small Radio Shack project box ($2.99). Splice the TREAD into the walwart leads at a convenient point, taking care to get the polarity right on the output - the walwart connectors are typically center-positive. Such a combination will give you more flexibility for your investment.

As long as you include a decent heat sink, you are better off with a 24V AC-AC walwart. That's because with rectification, you'll get a minimum of 32V into the regulator. That will give you voltages as high as 29-39VDC into the amp (the regulator burns a few volts). Many of these amps will perform better with the higher voltages. (Be careful with some opamps - they are limited to 24V total - AD8620/8610 is one that comes quickly to mind.) The downside is that if you don't use that higher voltage capability, you have to burn it off in heat through the heat sink on the regulator - but that's a fact of life for many of us. That said, the PIMETA will develop very little heat in the TREAD regulator.

As for an input plug - yes, you have to purchase one separately. Take note of the walwart plug - most are 2.1 or 2.5mm connectors. You need to be sure to buy the corresponding socket of the same internal diameter. I settled on 2.1mm for everything I build, but 2.5mm seems just as plentiful.

EDIT: wrote too much as usual, and Fallen Angel beat me to it.

 

[mminutel]

Thanks everyone. Here is another question. Should I just get Tangent's packet that has everything or should I order more solid components?