Meta 42, high pass filter help needed.
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Dreamslacker

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Well, hello everyone.. My first post here after observing for a few days.


I've just got the parts to build the the Meta 42 amp. I'm following the schematics only so I'd not be using the PCB from tangent.

The problems comes with C1 & R2 of the setup. Since it's stated that using a 0.1uF cap with a 100K resistor would have "significant attenuation and phase distortion", I've got myself some 0.22uF Metalized Polypropylene Capacitors (Evox PMR's; The best I can get in Singapore) and 1M, 1% resistors for C1 & R2.

I'm not too sure about how to read the graphs from the Micro-cap 7 graphs but I assume the lower frequency to flat out on the graphs is better?

So it'd be fine if I used C1 as 0.22uF & R2 as 1 megaohms? Or should I raise C1 to 0.44uF?

It's alright to change their values at the moment since I've at least 1 week before the Farnell delivers to the shop I've placed the order for my EL2001CN's (I hate having to order; The shop is earning 20% from me).
 
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Dev

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Hello and welcome to Head-Fi!


It is good idea to use as bigger cap as it's possible, I guess. Sound love the great elements
. You will minimize cap's influence also, by this way...
 
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Dev

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Hmm... But if this is placing troubles... Well, as you wish
.
 
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Okay, thank you. Anyone else has any advice? I'm going to use a pair of Burr Brown OPA134PA's in there since I can't get the AD's or other BB Op-amp's without ordering. (yeah! another chance to get ripped off!)



I was looking at the Evox PFR5 series of Polypropylene film w/ metal foil capacitors but they only go up to 0.01uF for that series. The dissipations factor seems to be much better than with the PMR's I've got.

Although there is no way I can & will parallel 10 of these capacitors per channel. Not to mention the cost.
 
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puppyslugg

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You can order directly from AD and BB (TI). They both have 'sample' programs, too.


The Evox PFR5 caps would be a better choice. If your source has a cap at it's output or it has very low dc offset, you could eliminate the cap entirely. Which would be the best for sonics. Once again, if you wish to try it without a cap, check for offset.

It was cheaper to buy el2001/02 through the shop than directly from tangent?

Good luck.

 
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Quote:

Originally posted by puppyslugg
You can order directly from AD and BB (TI). They both have 'sample' programs, too.


The Evox PFR5 caps would be a better choice. If your source has a cap at it's output or it has very low dc offset, you could eliminate the cap entirely. Which would be the best for sonics. Once again, if you wish to try it without a cap, check for offset.

It was cheaper to buy el2001/02 through the shop than directly from tangent?

Good luck.


Well..

I live in Singapore (T.I.'s factory near my place packed up and left a few years back). So I've to place my orders with the shop. The shop gets their stuff from Farnell.
I did contemplate calling Farnell and ordering directly from them but I do not know if they would entertain my small orders. heh...
I might call them up later to check if they do since I forgot to fill in an order for a Netrik jack with the Elantec's!
They don't seem to have any decent dual-potentiometers with them. No Clara's, Nobles, Alps or anything.
So I'll either stick with some crappy dual pot or build my own control with a multi-pole switch. (Not possible for more than 3 settings due to size constraints)

As for the PFR5 capacitors, they don't have anything larger than 0.022uF. I can get the 0.01uF's & 0.022uF's at the shop though.

I do suppose I could pair them (0.022uF PFR5) up with the 1 megaohm resistors I've got. The graph in micro-gap seems to be identical to that of 0.22uF with 100K ohm resistor. Do you think it's better?
 
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puppyslugg

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Dreamslacker:

I would suggest paralelling the 2 or more of the .22 you have +.02uf PFR5 in paralell.
 
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Quote:

Originally posted by puppyslugg
Dreamslacker:

I would suggest paralelling the 2 or more of the .22 you have +.02uf PFR5 in paralell.


Hmm.. That is very possible. Thanks.

I've still got the problem of the volume control to solve. BUt I think it's alright to try and use a 3 way switch to make a Lo/Mid/Hi control.
 
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puppyslugg

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Dreamslacker:

You may want to try one those 'fake' alps. They're not too expensive and they are in Hong Kong.

wkleung8@163.com
 
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I don't intend on buying things online actually. But thanks anyway.. Will post pictures when I'm done with the amp. The shop gave me the wrong resistors.. Damn.. 220K ohms became 22K ohms.. And I've 2 less 1K ohm resistors (I forgot to count them in for the CCS).
 
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Hmmz... It's working fine now. I've jumpered the 3 sockets for the EL2001CN's. The shop just gave me a call earlier to tell me that they've received the stock from Farnell.



Even without the buffers, it's extremely LOUD! w00t.... Pretty darn good, I must say..

Only thing is my dual voltage splitter just uses 2 22K ohm resistors as I can't get TLE2426 (are there subsitutes?). No diodes as I'm having problems with them.

Just a functioning Cmoy amp. at the moment.. Until I plug the buffers in tomorrow! hehehee..
 
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