Topic: another DIY preamp and some links

[kuuan]

Built another preamp, see circuit: http://sound.westhost.com/project13.htm

I made the figure 2 modified version for 12 Volt, point to point soldering, fit it into a small box and power it with an 'external' 9 Volt battery, see below.
OK, it is not a beauty, I had bought cheap parts in a local shop in Thailand, but it works that well that I plan on building one more once I find a nice metal box. It made lots of fun to build and really is very noise free.

Of course I made two circuits to have stereo and added a 9 Volt plug-in power supply. I simply terminated it with two stereo mini females, one for Mic-in, one for 'out', one power switch, one pot for gain control and one switch to turn on/off mic in power supply ( as the AT822 does not, but the Giant Squids and the coming CMC4s want the 9 Volts )
 
With the AT822 no noise at all noticable, but with the Giant Squids there is some noise.


However I wonder if I had better changed some values of resistors to optimize it for 9 Volts, but I do not know how to calculate them. For the mic-in power I used 6,8 kOhm Res. and 22uF Caps and though it works I am not sure if their value could better be changed.
Anybody here who can answer this questions?
I asked them here: http://sound.westhost.com/phpBB2/viewtopic.php?t=1086 ( answer 3, username kuuan ) but there are no answers yet.

If you only consider ballanced see:
http://sound.westhost.com/project66.htm
a simple unballanced to ballanced solution:
http://www.fivefish.net/diy/balanced2/default.htm resp. http://www.fivefish.net/diy/balanced/default.htm
to understand ballanced: http://www.tangible-technology.com/power/Phantom_Power_connect.html

mixers:
http://www.aaroncake.net/circuits/mixer2.htm
http://home.maine.rr.com/randylinscott/may20.htm
http://sound.westhost.com/project94.htm ( this one I really would like to build, but have many questions - which I posted at the forum of that site in section 'preamp', but no replies yet - somebody here will check it out? )

linkpools:
http://www.izatech.ro/linkuriaudio.htm
http://www.epanorama.net/




http://

[celticrogues]

Cool stuff!
Hof hard was this to build?
I am relatively new to DIY, but have built a couple of mics and was thinking about getting into some preamps next. Thanks!
-Mike

[kuuan]

I found it very easy to build, I even had much fun building it. However some previous experience with soldering electronic parts could be essential. I really recommend making it yourself as it is a lot of fun and doesn't cost much.

I had bought all parts to build one more but this time inside a metal box, and I just arrived in Japan where I know a shop where I can get nice metal boxes. In case I will make that other one I could sell the first one which can be seen on the foto, if interested you could make me an offer.
BTW I also had found a very nice product, an Audio Technica Mic Preamp which is only sold in Japan, see: http://www.audio-technica.co.jp/products/dj-plus/at-ma2.html
I could find the time to buy one and send it to anybody who want one and is willing to pay a small premium for my efforts, e.g. 80 USD plus shipping. For this prize I'd include an external 9 Volt battery box with the right connector soldered to it to power the unit.

[Nick's Picks]

while this project is interesting, I find this more interesting:
"Everything you do through out the day, every thought and every feeling leaves an impression stored inside you.
These impressions create tendencies, their sum total is your character."

[kuuan]

while this project is interesting, I find this more interesting:
"Everything you do through out the day, every thought and every feeling leaves an impression stored inside you.
These impressions create tendencies, their sum total is your character."

Hi Nick,

I am happy you like that quote.

It is a personal abbreviation of contents taken from a small booklet called:
'The Probem is You, the Solution is You' by Swami Dayanand Saraswati. ( A foremost teacher and expounder of 'Vedanta', the essential teaching of the ancient scriptures of the Vedas of India )

The booklet can be ordered for 2 USD here: http://www.arshavidya.org/ at the bookstore section.
Get a good introductory article online clicking 'readings' on the main page.

I hope nobody minds this post for being off topic.
In case the admin. decides to delete this post please be so kind and send it as a PM to Nick first.
thank you.

and: disclaimer: I am not affiliated to the organisation mentioned and personally believe that there is too much sold as the only truth or in other way exclusive to the interested in the spiritual.

[poorlyconditioned]

I found it very easy to build, I even had much fun building it. However some previous experience with soldering electronic parts could be essential. I really recommend making it yourself as it is a lot of fun and doesn't cost much.

I had bought all parts to build one more but this time inside a metal box, and I just arrived in Japan where I know a shop where I can get nice metal boxes. In case I will make that other one I could sell the first one which can be seen on the foto, if interested you could make me an offer.
BTW I also had found a very nice product, an Audio Technica Mic Preamp which is only sold in Japan, see: http://www.audio-technica.co.jp/products/dj-plus/at-ma2.html
I could find the time to buy one and send it to anybody who want one and is willing to pay a small premium for my efforts, e.g. 80 USD plus shipping. For this prize I'd include an external 9 Volt battery box with the right connector soldered to it to power the unit.

Did you buy that preamp?  Can you take a picture of the insides?  I might be interested in getting one.  Please PM me a price *without* the battery box to power it (I would do this myself).

Thanks!
  Richard

[Chuck]

Yeah, that pre-amp interests me too. Like Richard, I'm not interested in the battery box option either.

[kuuan]

Richard and Chuck,

Are you interested in the AT-AM2
or the DIY preamp I had mentioned in the beginning of this thread?

If it is the AT-AM2:

• I have one which I could send you right now from Japan, but it would come without the 110 Volt DC adapter
• I could send you 'mine' including the 110 DC adapter after about 10 days from Austria ( where I had left the DC adapter ) note: it as as much as new, bought abt. 3 months ago, but the paint of the screws has come off somewhat as I had opened the box to have a look inside
• Or I could go to downtown Osaka tomorrow to get two new AT-AM2s and send them to you directly from Japan ( I will go downtown tomorrow anyway to get some electronic parts, and if it was getting two AT-AM2 it would be worthwhile the extra detour I'd have to take )

here is a Pic of the AT-AM2's inside:
http://i39.photobucket.com/albums/e190/kuuan/IMGA2558.jpg

If it is the DIY preamp:
You could get the one in the foto http://i39.photobucket.com/albums/e190/kuuan/IMGA2584.jpg which consists of two of those: http://sound.westhost.com/project13.htm circuits with an added 9 Volt Mic-in powering function which can be switched on/off
or I could make a new one considering personal preferances of it's finishing ( connectores etc. )

Please let me know soon ( max. 20 hours from now ) as tomorrow  is my last chance to go downtown Osaka before leaving Japan to either get the AT-AM2 or the parts to make the DIY preamp.

[Chuck]

Richard and Chuck,

Are you interested in the AT-AM2
or the DIY preamp I had mentioned in the beginning of this thread?

If it is the AT-AM2:

• I have one which I could send you right now from Japan, but it would come without the 110 Volt DC adapter
• I could send you 'mine' including the 110 DC adapter after about 10 days from Austria ( where I had left the DC adapter ) note: it as as much as new, bought abt. 3 months ago, but the paint of the screws has come off somewhat as I had opened the box to have a look inside
• Or I could go to downtown Osaka tomorrow to get two new AT-AM2s and send them to you directly from Japan ( I will go downtown tomorrow anyway to get some electronic parts, and if it was getting two AT-AM2 it would be worthwhile the extra detour I'd have to take )

here is a Pic of the AT-AM2's inside:
http://i39.photobucket.com/albums/e190/kuuan/IMGA2558.jpg

If it is the DIY preamp:
You could get the one in the foto http://i39.photobucket.com/albums/e190/kuuan/IMGA2584.jpg which consists of two of those: http://sound.westhost.com/project13.htm circuits with an added 9 Volt Mic-in powering function which can be switched on/off
or I could make a new one considering personal preferances of it's finishing ( connectores etc. )

Please let me know soon ( max. 20 hours from now ) as tomorrow  is my last chance to go downtown Osaka before leaving Japan to either get the AT-AM2 or the parts to make the DIY preamp.

kuuan:

Thanks for taking the photo. After seeing the interior, I'm no longer interested in that pre-amp.

Chuck

[poorlyconditioned]

Richard and Chuck,

Are you interested in the AT-AM2
or the DIY preamp I had mentioned in the beginning of this thread?

If it is the AT-AM2:

• I have one which I could send you right now from Japan, but it would come without the 110 Volt DC adapter
• I could send you 'mine' including the 110 DC adapter after about 10 days from Austria ( where I had left the DC adapter ) note: it as as much as new, bought abt. 3 months ago, but the paint of the screws has come off somewhat as I had opened the box to have a look inside
• Or I could go to downtown Osaka tomorrow to get two new AT-AM2s and send them to you directly from Japan ( I will go downtown tomorrow anyway to get some electronic parts, and if it was getting two AT-AM2 it would be worthwhile the extra detour I'd have to take )

here is a Pic of the AT-AM2's inside:
http://i39.photobucket.com/albums/e190/kuuan/IMGA2558.jpg

If it is the DIY preamp:
You could get the one in the foto http://i39.photobucket.com/albums/e190/kuuan/IMGA2584.jpg which consists of two of those: http://sound.westhost.com/project13.htm circuits with an added 9 Volt Mic-in powering function which can be switched on/off
or I could make a new one considering personal preferances of it's finishing ( connectores etc. )

Please let me know soon ( max. 20 hours from now ) as tomorrow  is my last chance to go downtown Osaka before leaving Japan to either get the AT-AM2 or the parts to make the DIY preamp.

Thanks for the generous offers, but I'm not interested either.

But, if you want to upgrade this yourself, you could add your own opamp there.  One obvious choice would be something like OPA2228.  This will improve the sound quite a bit.  There are lots of other opamps to try if you can't get that one.  Even the NJM2068 would be an improvement over what is in there now.

Why don't you put a socket in that sucker and try out some different opamps?

Thanks again!
  Richard

[kuuan]

Chuck, as you could tell only from the foto this is not a high quality but a simple preamp.

However it is of a sturdy built and has some nice features like it's on/off switch of mic-plug-in power, mono/stereo switch, gain selector and even a clipping light. As it is quite small, operates with a single 9 Volt battery and certainly is way better than the built-in preamp of e.g. the iRivers it does make a quite useful tool for somebody who owns an iRiver and wants a cheap, very portable and reliable preamp solution which also powers mics! - like the SP-CMCs. ( a battery box only costs not much less $$ )

Richard, thank's a lot for the suggestions. I shall try to get the opamp(s) you mentioned just for the sake of experimenting and playing.

I slightly prefer my selfmade preamp mentioned in the beginning of this thread which does without any opamp for being even smaller and because it's sound is cleaner, it's self sound almost zero.

[Church-Audio]

Chuck, as you could tell only from the foto this is not a high quality but a simple preamp.

However it is of a sturdy built and has some nice features like it's on/off switch of mic-plug-in power, mono/stereo switch, gain selector and even a clipping light. As it is quite small, operates with a single 9 Volt battery and certainly is way better than the built-in preamp of e.g. the iRivers it does make a quite useful tool for somebody who owns an iRiver and wants a cheap, very portable and reliable preamp solution which also powers mics! - like the SP-CMCs. ( even a battery box alone usually sells for more $$ )

Richard, thank's a lot for the suggestions. I shall try to get the opamp(s) you mentioned just for the sake of experimenting and playing.

I slightly prefer my selfmade preamp mentioned in the beginning of this thread which does without any opamp for being even smaller and because it's sound is cleaner, it's self sound almost zero.

Try the OPA2227A as well thats a nice sounding opamp, I use this one for some of my preamps.

[kuuan]

thank's a lot everybody, also Chris for your additional opamp suggestion.

How would you Guys, who can read electronic circuits and have a lot of experience, qualify the DIY preamp?
Certainly also nothing for pros, but what's your take?
Maybe you even could tell me how to optimize it for the operation of 9 Volts? ( it was built for 12 Volts )
and if the 6,8 kOhm Res. and 22uF Caps I chose for the Mic-plug-in power are correctly chosen?

- and I did have some problem with the gain control and had changed it's design to make it work -
if someone wants to help I'll elaborate.

[Church-Audio]

thank's a lot everybody, also Chris for your additional opamp suggestion.

How would you Guys, who can read electronic circuits and have a lot of experience, qualify the DIY preamp?
Certainly also nothing for pros, but what's your take?
Maybe you even could tell me how to optimize it for the operation of 9 Volts? ( it was built for 12 Volts )
and if the 6,8 kOhm Res. and 22uF Caps I chose for the Mic-plug-in power are correctly chosen?

- and I did have some problem with the gain control and had changed it's design to make it work -
if someone wants to help I'll elaborate.

I like 10k for bias and 10uf for decoupling caps on a preamps front end. I don't think you need to go to 22uf I think this circuit will run on 9 volt no problem. As far as telling what its going to sound like its very hard I have seen the most stupid schematics for a preamp design sound great. So you can not tell by looking I don't like all the electrolytic caps in the circuit so it would not be a design I would consider just for that reason. That is not to say its a bad preamp. Never judge a preamp by its schematic, or cover listen first judge second.

[kuuan]

thank's a lot Chris.

I don't think you need to go to 22uf

better to substitute them with 10 uF?

I don't like all the electrolytic caps in the circuit

could I substitute them with ceramic caps and would that improove the it's performance?

about the gain selector problem I had:
In the circuit drawing it shows the symbol of a simple resistor but as it should be adjustable I used a potentiometer instead. I connected line from between R1 and C1 to the Terminal 3 of the pot., terminal 2 went to the output, and I connected terminal 1 to ground. However it did not work propperly, therefore I tried all other possible connections but it never worked.
In the end I simply connected the 'output' of the circuit to the terminal 3 of the pot and terminal 2 became the new 'output'. ( and terminal 1 I connected to ground, though leaving it without connection also worked )

Why would the pot with the original wiring not work? or more imprtantly, is my 'work around' OK?