useless...um I mean useful information
Mar 28, 2006 at 9:07 PM Thread Starter Post #1 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
The only RIGHT way to do tone controls,filters,even a simple "loudness" control is the old CLR filters and NOT opamp "synthesized" filters so why is this method not seen as a often ?

cost and no more !

the coils cost a small fortune usually and when you weight the cost of an opamp with a couple of resistors and caps against the price of just one quality inductor,then add up all you need for say a 10 band EQ and it is easy to understand why manufacturers shy away and then go on to "con" you into beleiving the cheap method is actually the best method (all about selling you a product folks,that and a line of bull).


Here is a lnkmthat can shave the cost a LOT but means you do the work.
DIY X 10
tongue.gif


http://recording.org/users/kev/Inductors.htm
 
Mar 29, 2006 at 12:15 AM Post #2 of 37

Garbz

Headphoneus Supremus
Joined
May 19, 2004
Posts
3,573
Likes
12
Dammit if I wasn't trying to fit my next amp in the same space as a 9v battery I'd be all over this
frown.gif
 
Mar 29, 2006 at 12:48 AM Post #3 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
very_evil_smiley.gif
I have a link some to some really tiny inductors that actually work at audio frequencies well in case you change your mind
very_evil_smiley.gif


BTW-last pice of the puzzle arrived today so when I get to it and pack the shipment then get my a*s to the post office I have coming at you :

1-Mixed Signal Hardware and Housekeeping Techniques
2-Op-Amp hardware and Housekeeping Techniques
3-A Designers Guide To InAmps
4-Switches and Multiplexers

A nice little collection of I.C. circuit design reference books

wink.gif
 
Mar 29, 2006 at 3:32 AM Post #5 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
That joint is crazy in price but the principles are definately worthy,just not using the products from that site.

I use a variation on the tapped transformer volume control every day
icon10.gif
 
Mar 29, 2006 at 1:11 PM Post #6 of 37

Garbz

Headphoneus Supremus
Joined
May 19, 2004
Posts
3,573
Likes
12
Quote:

Originally Posted by Tomo
Check out the COST!! ... Nearly gave me a heart attack.


For a moment i laughed and thought he didn't see that it said Swiss Francs (CHF). Then i looked again and remembered the Swiss Franc has a bid price of 1.08 to the auzzie dollar. That price is insane!!!!

Quote:

Originally Posted by rickcr42
A nice little collection of I.C. circuit design reference books


You ain't wrong. I can't thank you enough for that.


Quote:

Originally Posted by rickcr42
very_evil_smiley.gif
I have a link some to some really tiny inductors that actually work at audio frequencies well in case you change your mind
very_evil_smiley.gif



Link me. I need a 10mH and a 2.2mH inductor for this tiny project anyway to notch out nastyness in the ER-4P earphones.

Btw generally how do you rate inductors in the audio signal path. I've already ordered reasonably generic inductors in the right values for the notch filter. On a nastyness of 1-10, 10 being an electrolytic or cermaic cap?
 
Mar 29, 2006 at 3:54 PM Post #7 of 37

setmenu

Strongly opposes a DBT-free chair forum.
Joined
Nov 26, 2001
Posts
2,093
Likes
21
Quote:

Originally Posted by Garbz

Link me. I need a 10mH and a 2.2mH inductor for this tiny project anyway to notch out nastyness in the ER-4P earphones.

Btw generally how do you rate inductors in the audio signal path. I've already ordered reasonably generic inductors in the right values for the notch filter. On a nastyness of 1-10, 10 being an electrolytic or cermaic cap?



Hi Garbz
How tiny do want the inductors to be?
The bobbin inductors I use in my ER4 filter network are pretty small.

http://www6.head-fi.org/forums/attac...3&d=1123840257

I would be interested to see the 'tiny' inductors Rick is speaking of.
What frequencies are you attacking on your ER4's?


As for the effect of such filters or their components on the signal path, well
without them I am not too keen on the ER4 sound and with them LOVE it.
Not very purist audiophile I know but then again plenty of people don't think
using headphones is either..
So I am not shy about using a bit of [lcr] filtration these days, though the
temptation to spend time tweaking and the values can become compulsive.
redface.gif



.
 
Mar 29, 2006 at 4:23 PM Post #8 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
will get back on the "minis" but has anyone used these trafos/inductors ?

http://www.carnhill.co.uk/

you can see a sorta cross reference here

http://www.vintagedesign.halmstad.ne...ross_table.htm

Back OT :

Quote:

Btw generally how do you rate inductors in the audio signal path. I've already ordered reasonably generic inductors in the right values for the notch filter. On a nastyness of 1-10, 10 being an electrolytic or cermaic cap?


Using a simple line level bridging trafos as the example you need to realise that like a cap there is a sonic "trait" to some audio transformers likie for instance the Jensen/CineMags tend to the nutral side and the Lundahl/Sowters tend to romantic.


Using ANY cap as the comparison on a 1-10 scale an inductor/trafos is a -2
tongue.gif


...but you need also be aware of any AC fields and layout IS critical if you don't want to build a hornets nest (all hum and buzz
very_evil_smiley.gif
)

Gotta jet for a few hours but will get thos link s out later
wink.gif
 
Mar 30, 2006 at 3:19 AM Post #9 of 37

Garbz

Headphoneus Supremus
Joined
May 19, 2004
Posts
3,573
Likes
12
Hmmm seems to be small enough.

Trying to get a TPA6120 + 3db in bass below 140hz, -4db notch at 2.5k -6 db at 7k and a 74ohm resistor to convert the 4P->4S along with 2x9v batteries, or 8x AAA batteries and psu buffer/filter into a case the size of a credit card
basshead.gif


You say it's impossible yeah so do I, but if I aim that high I may just get close.
 
Mar 31, 2006 at 12:22 PM Post #11 of 37

Garbz

Headphoneus Supremus
Joined
May 19, 2004
Posts
3,573
Likes
12
It maybe. The only trouble is sourceing them. I did get my inductors today. THey are round and FAT not thin and long as advertised. Means I need to re-think the layout
frown.gif


I'd love to go SMD except there's no place which doesn't sell them without A) a minimum order of 50, or B) $25 shipping from the states.
 
Mar 31, 2006 at 1:18 PM Post #12 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
Quote:

I'd love to go SMD except there's no place which doesn't sell them without A) a minimum order of 50, or B) $25 shipping from the states.


$25 shipping,$5 in parts.An old story man,even for us in the States for some goods available only at certain outlets.Have you tried manufacturer direct ?
 
Apr 1, 2006 at 12:30 AM Post #13 of 37

Garbz

Headphoneus Supremus
Joined
May 19, 2004
Posts
3,573
Likes
12
Not yet I haven't. Mind you I have another interesting problem now. Thoes inductors I ordered are 10mH and 2.2mH, The 10mH have a DCresistance around 50ohm and don't notch out anywhere near enough, and the 2.2mH in their place have a Q that's waaaay to low, and require way to high of a capacitance to get the filter down to 2.5k

So the question is this. I have the option of getting new inductors, possibly better, possibly smaller, or raising the output impednace of the amp from 20ohm to 100ohm.

I'm ordering from Wes since they are the cheapers in Australia w.r.t shipping but their catalogue has no data on them (otherwise i wouldn't have ordered the 10mH ones in the first place :S). They have the long resistor like RF Chokes (which I bought), and compact 6x8mm inductors (round) which say Q60-80 minimum. I don't know what this means but I'm wondering if they would have a lower DC resistance Typically.

If I can't confirm anything I'll re-think the design and maybe just go the 100ohm output resistors.
 
Apr 1, 2006 at 3:35 PM Post #14 of 37

rickcr42

Are YOU talkin' to me?
Joined
Jun 21, 2001
Posts
13,874
Likes
14
Quote:

So the question is this. I have the option of getting new inductors, possibly better, possibly smaller, or raising the output impednace of the amp from 20ohm to 100ohm.


line stage ? If yes then 100 ohms (or even 300 single ended) is more than fine
 
Apr 1, 2006 at 4:16 PM Post #15 of 37

setmenu

Strongly opposes a DBT-free chair forum.
Joined
Nov 26, 2001
Posts
2,093
Likes
21
Hi Garbz
I found that I did not really need much cut at any frequency.
My inductors range from dc r of around 9 for 3.3mh and 40 for the 10mh.
My own filter cuts a little at 2.5k boosts a little over 10k and produces
a gentle hump centered around 220hz this is coupled with very low end boost from the amp.
The filter uses a 27 ohm input R [the source R for the notch cuts]followed an 47ohm r to make up the S resistance.
The boost notches bypass the 47 ohm attenuator to achieve their gain.
Using my circuit to achieve a gain in low bass would need pretty large values
of cap and inductor, and being on the amp output also a low Dc R inductor which means bulk.
That why my low end is done at the amp.
Perhaps I am misunderstanding you?



.
.
 

Users who are viewing this thread

Top