carlosfm said:
No problem Carlos🙂 I'll try it out and post the results, the SR's gave fanatstic results with the Naim based Air-Guitar pre and various cdp's etc, its also suposed to work very well powering Guido's crystal Oscillator.
Fingers crossed it works well with the AD815😀
Nuuk said:
You don't mean that I am corresponding with criminal elements?
Has Carlos been a naughty boy
Super Regs and all that
Hello T.
Can I suggest that you try both the ALW SR as well as the simple 317/337 route I tried?
I also have some of those SR's but frankly if the 317/337 after the initial 317/337 is good enough then I can use the SR in other parts of the system!
Carlos, would be interesting to see if you got similar results. The AD815 rocks!
Hello T.
Can I suggest that you try both the ALW SR as well as the simple 317/337 route I tried?
I also have some of those SR's but frankly if the 317/337 after the initial 317/337 is good enough then I can use the SR in other parts of the system!
Carlos, would be interesting to see if you got similar results. The AD815 rocks!
Re: Super Regs and all that
Ok, thats easy enough, I can add the extra regs on a bit of vero board to compare.
BTW have you tried adding something like a TL431 on the adjust pins?
Dr.H said:
Ok, thats easy enough, I can add the extra regs on a bit of vero board to compare.
BTW have you tried adding something like a TL431 on the adjust pins?
Re: Super Regs and all that
I'll see if I find an easy way to compare, maybe a switch between two PSUs.
It's not easy to take the pre out of my system... too many cables connected there.
The 6 inputs are full, the 3 tape outputs too, the two pre outs too.
😛
Dr.H said:
I'll see if I find an easy way to compare, maybe a switch between two PSUs.
It's not easy to take the pre out of my system... too many cables connected there.
The 6 inputs are full, the 3 tape outputs too, the two pre outs too.
😛
TL431 on ADJ pins
Hi T.,
Neil Mcbride had an interesting scheme using LM329DZ on the ADJ pin to lower noise. I have some lying at home. It could be worth trying.
From his site:
"This second regulator stage is slightly different and incorporates a voltage reference, which improves the output stability, line regulation, thermal regulation, drift and noise by a factor of about 7, and in use it's a lot better audibly than the first one".
See the following for discussion: http://www.neilmcbride.co.uk/preamp.html
Hi T.,
Neil Mcbride had an interesting scheme using LM329DZ on the ADJ pin to lower noise. I have some lying at home. It could be worth trying.
From his site:
"This second regulator stage is slightly different and incorporates a voltage reference, which improves the output stability, line regulation, thermal regulation, drift and noise by a factor of about 7, and in use it's a lot better audibly than the first one".
See the following for discussion: http://www.neilmcbride.co.uk/preamp.html
What is an acceptable level on dc offset?
Got it all together wondering wether to plug into my main setup, getting around 0.09 v at the moment I think. Is this too much?
phil
Got it all together wondering wether to plug into my main setup, getting around 0.09 v at the moment I think. Is this too much?
phil
filholder said:
Yes, it's too much, but not a problem if you have an input cap on your amp.
You need to adjust DC offset with a pot of the same value you will use on the pre (10k~20k), set at 9~10 o'clock position. Without the pot (only the 100k resistor to ground), DC is higher.
You adjust to 0 mv at this pot setting (which is what you use most of the times), and then you'll have some 20~30mv at max volume setting, which I hope you will never use when listening to music. 😎
My values are different
I am using a 25K pot and 1800 ohm dcr input transformer on the input side of mine. There is a 1.3K resistor in series with the AD815.
The dc only varies 8 mv. Got it nulled to about -2 mv, goes up to about 6 mv and then back to -2 mv at the other end of rotation.
I cannot recommend using this circuit without a cap either on the output of the pre or the input of the amp.
I will build another one in a month or so. This time two AD815's and two nulling circuits. Along with discrete widebandwidth regs. I like the idea of using the LM327DZ references on the 317/337 regs also. But the drawings were confusing.
George
carlosfm said:
I am using a 25K pot and 1800 ohm dcr input transformer on the input side of mine. There is a 1.3K resistor in series with the AD815.
The dc only varies 8 mv. Got it nulled to about -2 mv, goes up to about 6 mv and then back to -2 mv at the other end of rotation.
I cannot recommend using this circuit without a cap either on the output of the pre or the input of the amp.
I will build another one in a month or so. This time two AD815's and two nulling circuits. Along with discrete widebandwidth regs. I like the idea of using the LM327DZ references on the 317/337 regs also. But the drawings were confusing.
George
Re: My values are different
That's exactly what I recommend.
Eiter, not both.
The only dc coupling caps I use are on the inputs of my amp.
Even my dac doesn't have (and doesn't need) them.
Panelhead said:
That's exactly what I recommend.
Eiter, not both.
The only dc coupling caps I use are on the inputs of my amp.
Even my dac doesn't have (and doesn't need) them.
Right well my 815 preamp aitn working at all, getting a pulsing sound and that about it. Rudi if you about any hints on fault find? Sorry to be a pain. I thought by getting the PSu up and running it wouldnt be that tough.
Oh well.
Oh well.
Hi Phil
don't dispair.
1-first do not connect the LED. leave them out for now.
2-check that all your caps are the right way round
3-check that you haven't swapped the 317 an 337
4 check for solder bridges or a track that didn't etch properly.
5-check that you have your diodes the right way round
6-check that the opamp is the correct way round
i know all these things are common sense but have another look at it
send me a picture of the top of the PSU and of the daughter board. and the same of the bottom.
don't dispair.
1-first do not connect the LED. leave them out for now.
2-check that all your caps are the right way round
3-check that you haven't swapped the 317 an 337
4 check for solder bridges or a track that didn't etch properly.
5-check that you have your diodes the right way round
6-check that the opamp is the correct way round
i know all these things are common sense but have another look at it
send me a picture of the top of the PSU and of the daughter board. and the same of the bottom.
Thanks a lot Rudi I'll take some pictures tonight and start my checking, sorry i just got a bit dishearten last night and end up walking away and play xbox till 3 to cheer myself up. Bad move, todays all going a bit hectic from lack of sleep. And to make things fun the DNS server went down at work and we ha d afew minutes to fix it. Joy.
Ill be in a better state of mind tonight.
Phil
Ill be in a better state of mind tonight.
Phil
filholder said:
Eventually you will get used to it
when i started with this stuff it drove me insanefilholder said:
No problem, but yes it was a bad move.
You would be better spending your time watching Benfica-Liverpool. 😀 😀 😀
No i had already had the pleasure of watching a heavy injured and patched up Arsenal rip apart Real, now that was a shocking and truly fun games.
Not least becuase the missus is from Madrid so every time i shouted with joy she gave me a punch.
Not a good night for my project but a great night!!
Well done against Liverpool
Not least becuase the missus is from Madrid so every time i shouted with joy she gave me a punch.
Not a good night for my project but a great night!!
Well done against Liverpool
Back to a better sounding preamp
I am slowly delving into the power supply options. Read the info on improving the Naim power supplies. Wish those were split rail circuits.
Found a drawer with LT1086 regs today. Can these work okay used like the LM338 is with two used to do +/- rails? Does not look like LT has a matching reg here.
If so, will those LM329DZ's be useable on an upside down reg? My next trip into the AD815 will be getting away from heavy passive filtering and getting more modern.
Gunna cop Borbely's reg circuit with more modern parts and then try a spiffed up 3 pin board also. Borbely uses those 6.9 volt references in his discrete circuit.
I do not know if a better reg will improve my line buffer. But it cannot hurt. Power supply improvements always seem to pay big benefits.
George
I am slowly delving into the power supply options. Read the info on improving the Naim power supplies. Wish those were split rail circuits.
Found a drawer with LT1086 regs today. Can these work okay used like the LM338 is with two used to do +/- rails? Does not look like LT has a matching reg here.
If so, will those LM329DZ's be useable on an upside down reg? My next trip into the AD815 will be getting away from heavy passive filtering and getting more modern.
Gunna cop Borbely's reg circuit with more modern parts and then try a spiffed up 3 pin board also. Borbely uses those 6.9 volt references in his discrete circuit.
I do not know if a better reg will improve my line buffer. But it cannot hurt. Power supply improvements always seem to pay big benefits.
George
Hi Guys,
I was busy last trying out a few things with the regs
First thing was dual regs which was wired up on a piece of vero, listening impressions, well I got mixed results, the bass did sound deeper but it sounded a little artificial to me, the mids seemed sweeter but wider.
I think I'll have to play about with this, it could be due to my bodged extra circuit, value caps, I'm not sure.
Now the strange thing was when I fitted the LM329 as on the McBride site posted by Ryan, Did I get your name right🙂
This changed the tone, its hard to explain but definately had an effect according to my ears😀
I'm going to spend some more time on this, it may prove to be a good mod, first I need the dual regs to sound right before going further with the LM329's
The last thing to be tried was ALW SR's, there was an imediate difference with these😱 lots of power,speed and width, maybe a little too bright and forward but bloody impessive🙂
I've lowered the 100uf smd cap that was on the daughter board to 10uf, the SR's like to see lower capacitance.
I've also changed some of the caps on the SR's, they was all originally Rubycon ZA's, I've replaced the output caps to 47uf Stargets which calmed the forwardness down
Theres now more experimenting to be done but it does prove the psu on these AD815 are important😉
I was busy last trying out a few things with the regs
First thing was dual regs which was wired up on a piece of vero, listening impressions, well I got mixed results, the bass did sound deeper but it sounded a little artificial to me, the mids seemed sweeter but wider.
I think I'll have to play about with this, it could be due to my bodged extra circuit, value caps, I'm not sure.
Now the strange thing was when I fitted the LM329 as on the McBride site posted by Ryan, Did I get your name right🙂
This changed the tone, its hard to explain but definately had an effect according to my ears😀
I'm going to spend some more time on this, it may prove to be a good mod, first I need the dual regs to sound right before going further with the LM329's
The last thing to be tried was ALW SR's, there was an imediate difference with these😱 lots of power,speed and width, maybe a little too bright and forward but bloody impessive🙂
I've lowered the 100uf smd cap that was on the daughter board to 10uf, the SR's like to see lower capacitance.
I've also changed some of the caps on the SR's, they was all originally Rubycon ZA's, I've replaced the output caps to 47uf Stargets which calmed the forwardness down
Theres now more experimenting to be done but it does prove the psu on these AD815 are important😉
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