Russ White said:
Actually... I just thought of something
It could be your V- rail is reading high because there is no load!!! The lm7912 needs at least a small load to regulate.
Things are probably just fine. I would attach everything and fire it up.
maf_au said:
Michael,
Glad to help! Sorry I did not think of this earlier, but one way to be sure th LM7912 is OK would be to put a ~2K 1/4W resistor accross the regulator output(V- rail) and ground, and then measure that rail. That will load the regulator with about 7.5ma if you then get ~12V on the negative rail then you are ok.
Cheers!
Russ
Ok, the preamp is up and running.
I measured the ma with shorted inputs and it was zero or 0.01mv, so given that Russ reckons the -ve rail will behave under load, I closed the case and connected it to the system.
I've had a listen, and I can state categorically that the FreeBird blows my Musical Fidelity amp to the weeds. The sound is both more open and detailed. My MF PreAmp is by no means their best, and it must be nearly 20 years old, but it's not a bad thing to beat either 🙂
Turn on is noisy if the poweramp is already running. anything I can do about that?
I'll try and give a critical opinion after work tonight.
Piccy attached of the FreeBird reigning over the test system...
Michael
I measured the ma with shorted inputs and it was zero or 0.01mv, so given that Russ reckons the -ve rail will behave under load, I closed the case and connected it to the system.
I've had a listen, and I can state categorically that the FreeBird blows my Musical Fidelity amp to the weeds. The sound is both more open and detailed. My MF PreAmp is by no means their best, and it must be nearly 20 years old, but it's not a bad thing to beat either 🙂
Turn on is noisy if the poweramp is already running. anything I can do about that?
I'll try and give a critical opinion after work tonight.
Piccy attached of the FreeBird reigning over the test system...
Michael
Attachments
maf_au said:
Well... You could add a turn on delay circuit and a relay, ala Mauro's ref amp, I am thinking baout making a board dedicated for that purpose as well. 😉
Michael, you did a superb job with your boards. You are a great sport. 🙂
Thanks!
Russ
Russ White said:
Careful, we might start a mutual admiration society
Wait till I remove the white paint from the aluminium volume knob and remove the blue protective coating from the case...
That's a good idea (the dedicated board) Be nice upgrade for a lot of gear I expect. I'll have some of them 🙂
Will you offer the Jaycar pot pcb as part of the preamp GB?
Regards,
Michael
FreeBird Construction and Listening impressions.
This preamp was completed this morning at around 8AM. It's been running continuously since. I don't know if these units will break-in, but it certainly isn't sounding worse each time I enter the room it's in!
Component selections and construction.
The parts used were basic items purchased mostly at Jaycar and futurlec. I've discovered Altronics locally, who seem to stock a greater variety of electronic stuff in some areas than Jaycar, and some parts came from them, including the case.
I used normal hookup wire for signal wiring, most of it Jaycar 13x0.12 cat# WH3000. I am sure there is better OFC etc wire to be had, and this stuff is light, and seems to harden and become brittle after soldering, I'd search for something better next time. If anyone has any favorites, I'd be happy to hear about them.
Mains wiring is all 240V or better rated. Not worth mucking around here. The transformer is a Jaycar MT2086 15-0-15v toroid. Fuse is 500ma slowblow. I have not yet installed a front panel led.
Russ kindly supplied the low-esr caps. I sourced the OPA627's via ebay at something like 80% discount off local prices.
If I was doing the construction again, things I'd change would be: Assemble in the box, not the plate. Use better/different signal wire. not much else.
I should mention that many of the tasks carried out over the last week or so to finish this project were shared by my son Hugh, who has high functioning autism. Some people might die of shock to hear that, but experience has taught us to follow his interests, and electronics is one of them. As soon as I open a package with components or PCBs these days, he tries to take over. There is no slacking on my projects, I'm not allowed to!
Listening Impressions:
I inserted the preamp into my 'test' system comprised of bit 'n pieces of cast off or excess gear that any hifi buff will have lying around:
I have a bit of Musical Fidelity gear that I either bought new on close-out, or from ebay, and some of it is in the test setup:
MF The Preamp 3a, MF P170 PowerAmp. The P170 was bought recently on ebay, and arrived in working order, but with a nasty PCB burn that I decided to fix myself. There's a thread in the solid state forum about it. It has upgraded (LM318 to OPA627) opamps, and new capacitors (almost) throughout.
Rotel 965BX CD player, and Tannoy 603 bookshelf speakers. (you may remember these by their 6-sided case construction) All good, dated but not great components.
The test system has been assembled and running for over a month since the arrival of the P170. We're familiar with how it sounds (respectable) there is one last job on the P170 which is replacement of the largish 20,000uf PS Caps.
Room is a large, bright kitchen/dine. No carpet, lots of wood and glass. The system sits on a 6' x 3' pine table. (The Dining table, actually) 😀
Enough rambling about the gear. Once the preamp was tested as behaving, I shut down the 3a, and inserted the new preamp:
Initial impressions: Wow. This is a lot more open and detailed. I swapped a few CD's, couldn't find anything that I could call a downgrade, everything was improved!
So what has changed? I'm hearing a lot more detailed and focussed soundstage. Instruments have been given more life. Bass is more defined and controlled, even though it is certainly lacking in these speakers, it's a lot better than it was. A good example of the difference is on Cohen's 'ten recent songs' Those of you familiar with this recording will know that there is a lot of bass in it, and previously, the CD was enjoyable, but there was a lot of mud down in the bass region that veiled the individual instruments both in their location and detail. No more. Leonard is now placable as is each of the instruments. I should dig out my Christy Moore 'Smoke and Strong Whisky', there is a very bass-heavy and awesome track on there called 'Burning Times' which will probably gain extra punch here. Well recorded female vocals are standout (they were great previously, but the extra soundstaging is welcome) Gillian Welch 'Soul Journey' visits to sing, mostly she stands just to the left of the right speaker. Great voice and delivery, well accompanied, and great recording made better by this terrific little preamp!
So, my first completed DIY Audio project is a success! I'm thrilled with the sound, and very happy with the whole result. I'd like to thank everyone, especially Russ for creating the preamp in the first place, being patient with my newbie questions, and even sending the board off to the other side of the planet in the hope that I would actually get them going. Pre dinner drinks are on, I'm off to do some more listening!
Regards,
Michael
P.S. I'll update my gallery in the next day or so, most of the project photo's are in this thread though.
This preamp was completed this morning at around 8AM. It's been running continuously since. I don't know if these units will break-in, but it certainly isn't sounding worse each time I enter the room it's in!
Component selections and construction.
The parts used were basic items purchased mostly at Jaycar and futurlec. I've discovered Altronics locally, who seem to stock a greater variety of electronic stuff in some areas than Jaycar, and some parts came from them, including the case.
I used normal hookup wire for signal wiring, most of it Jaycar 13x0.12 cat# WH3000. I am sure there is better OFC etc wire to be had, and this stuff is light, and seems to harden and become brittle after soldering, I'd search for something better next time. If anyone has any favorites, I'd be happy to hear about them.
Mains wiring is all 240V or better rated. Not worth mucking around here. The transformer is a Jaycar MT2086 15-0-15v toroid. Fuse is 500ma slowblow. I have not yet installed a front panel led.
Russ kindly supplied the low-esr caps. I sourced the OPA627's via ebay at something like 80% discount off local prices.
If I was doing the construction again, things I'd change would be: Assemble in the box, not the plate. Use better/different signal wire. not much else.
I should mention that many of the tasks carried out over the last week or so to finish this project were shared by my son Hugh, who has high functioning autism. Some people might die of shock to hear that, but experience has taught us to follow his interests, and electronics is one of them. As soon as I open a package with components or PCBs these days, he tries to take over. There is no slacking on my projects, I'm not allowed to!
Listening Impressions:
I inserted the preamp into my 'test' system comprised of bit 'n pieces of cast off or excess gear that any hifi buff will have lying around:
I have a bit of Musical Fidelity gear that I either bought new on close-out, or from ebay, and some of it is in the test setup:
MF The Preamp 3a, MF P170 PowerAmp. The P170 was bought recently on ebay, and arrived in working order, but with a nasty PCB burn that I decided to fix myself. There's a thread in the solid state forum about it. It has upgraded (LM318 to OPA627) opamps, and new capacitors (almost) throughout.
Rotel 965BX CD player, and Tannoy 603 bookshelf speakers. (you may remember these by their 6-sided case construction) All good, dated but not great components.
The test system has been assembled and running for over a month since the arrival of the P170. We're familiar with how it sounds (respectable) there is one last job on the P170 which is replacement of the largish 20,000uf PS Caps.
Room is a large, bright kitchen/dine. No carpet, lots of wood and glass. The system sits on a 6' x 3' pine table. (The Dining table, actually) 😀
Enough rambling about the gear. Once the preamp was tested as behaving, I shut down the 3a, and inserted the new preamp:
Initial impressions: Wow. This is a lot more open and detailed. I swapped a few CD's, couldn't find anything that I could call a downgrade, everything was improved!
So what has changed? I'm hearing a lot more detailed and focussed soundstage. Instruments have been given more life. Bass is more defined and controlled, even though it is certainly lacking in these speakers, it's a lot better than it was. A good example of the difference is on Cohen's 'ten recent songs' Those of you familiar with this recording will know that there is a lot of bass in it, and previously, the CD was enjoyable, but there was a lot of mud down in the bass region that veiled the individual instruments both in their location and detail. No more. Leonard is now placable as is each of the instruments. I should dig out my Christy Moore 'Smoke and Strong Whisky', there is a very bass-heavy and awesome track on there called 'Burning Times' which will probably gain extra punch here. Well recorded female vocals are standout (they were great previously, but the extra soundstaging is welcome) Gillian Welch 'Soul Journey' visits to sing, mostly she stands just to the left of the right speaker. Great voice and delivery, well accompanied, and great recording made better by this terrific little preamp!
So, my first completed DIY Audio project is a success! I'm thrilled with the sound, and very happy with the whole result. I'd like to thank everyone, especially Russ for creating the preamp in the first place, being patient with my newbie questions, and even sending the board off to the other side of the planet in the hope that I would actually get them going. Pre dinner drinks are on, I'm off to do some more listening!
Regards,
Michael
P.S. I'll update my gallery in the next day or so, most of the project photo's are in this thread though.
And i who have a half-finished Grounded grip Pre-amp (Bruce Rosenblit) lying around.......
Well, one can have many pre-amps.
I must say that i'm looking forward to the potential GB on boards 😀
Well, one can have many pre-amps.
I must say that i'm looking forward to the potential GB on boards 😀
Well, it's there when they arrive! Russ did it 🙂
I think he uses the same method as for the copper side: Print onto photo paper, Iron on with mum's best iron from the laundry, remove paper, leaving the overlay printing and clean it up, then, instead of etch, just lacquer it to make it permanent.
This is from memory of what Russ posted before. You should be able to find his post, maybe in the Mauro thread...
Michael
I saw the images of his boards right after I posted the ?... Sorry... The question was for Russ. 🙂
Hi Erik! Hi Michael! 😀
Yes its pretty simple.. Michael had it dead on pretty much.
You print out the component side mirrored with a laser printer on injet photo paper. I drill the mounting holes on the PCB which helps me line things up prior to ironing. Place the toner side on the component side, use the holes in the PCB to find the hole marks on the paper. Use some masking tape to hold it in place omce you get it lined up. Then get a piece of plain paper to put over the photo paper to help keep things from sticking to the iron(the back side get almost as sticky as the front of the inkjet paper) then put the iron on high and iron for a minute or two pressing very firmly but not so firmly as to cause the paper to shift which will blur things. Then pick the thing up (careful its freaking hot) and run it under luke warm water until its about room temp. And peel off the paper in one quick motion. Voila!!
Cheers!
Russ
Yes its pretty simple.. Michael had it dead on pretty much.
You print out the component side mirrored with a laser printer on injet photo paper. I drill the mounting holes on the PCB which helps me line things up prior to ironing. Place the toner side on the component side, use the holes in the PCB to find the hole marks on the paper. Use some masking tape to hold it in place omce you get it lined up. Then get a piece of plain paper to put over the photo paper to help keep things from sticking to the iron(the back side get almost as sticky as the front of the inkjet paper) then put the iron on high and iron for a minute or two pressing very firmly but not so firmly as to cause the paper to shift which will blur things. Then pick the thing up (careful its freaking hot) and run it under luke warm water until its about room temp. And peel off the paper in one quick motion. Voila!!
Cheers!
Russ
Member
Joined 2003
Hi Russ,
I am sorry that I am being slow in assembling the preamp to see how it works. We just got a huge order in at work so I am working 10 and 12 hour days and have not had time for anything really besides eating and sleeping. From what I hear thuogh the preamp sounds fantastic even when compared to some real high end gear. That's nice to hear, and I am very exited to get this project finished.
I am sorry that I am being slow in assembling the preamp to see how it works. We just got a huge order in at work so I am working 10 and 12 hour days and have not had time for anything really besides eating and sleeping. From what I hear thuogh the preamp sounds fantastic even when compared to some real high end gear. That's nice to hear, and I am very exited to get this project finished.
Hey DcibeL,
No need to apologize. 🙂 Real life should come first. 😀 No woories man, you just take care.
Cheers!
Russ
No need to apologize. 🙂 Real life should come first. 😀 No woories man, you just take care.
Cheers!
Russ
DcibeL,
Don't feel bad, I actually got mine completed quicker than I thought. My helper was harrassing me, so I gave in and we finished all the PCB's over a couple of nights, and then I went crazy motivated to get it working.
Today, I have removed the protective film from the case, and cut the paint off the volume knob. Looks extra good now, will post some piccies in the morning.
Extra sidebar regarding the difference in the soundstaging between the old preamp and the freebird:
My wife asked me tonight why the drums had moved 'there', and if that was 'supposed to happen', while she pointed to an exact spot behind the gear. We were listening to one of the Gillian Welch tracks after dinner. We've always had a soundstage with our gear, but it's significant that she has percieved the difference without prompting.
Michael
Don't feel bad, I actually got mine completed quicker than I thought. My helper was harrassing me, so I gave in and we finished all the PCB's over a couple of nights, and then I went crazy motivated to get it working.
Today, I have removed the protective film from the case, and cut the paint off the volume knob. Looks extra good now, will post some piccies in the morning.
Extra sidebar regarding the difference in the soundstaging between the old preamp and the freebird:
My wife asked me tonight why the drums had moved 'there', and if that was 'supposed to happen', while she pointed to an exact spot behind the gear. We were listening to one of the Gillian Welch tracks after dinner. We've always had a soundstage with our gear, but it's significant that she has percieved the difference without prompting.
Michael
Getting ready for GB
I am about to do Group Buys for both the FreeBird and the YardBird as well as the PS to go with either or both. 🙂
I want some opinions on adding input caps to the designs. If you don't use it you will need to jumper it, but it will allow those with DC coupled gear to use the pre-amp by using the cap. I would probably simply add a space for a .4" or .6" lead spaced cap(MKT etc).
Right now you could use a cap, but you would have to P2P to the pot or on the board. I think it makes things a little cleaner for those who want the safety of the input cap.
What do you think?
Cheers,
Russ
I am about to do Group Buys for both the FreeBird and the YardBird as well as the PS to go with either or both. 🙂
I want some opinions on adding input caps to the designs. If you don't use it you will need to jumper it, but it will allow those with DC coupled gear to use the pre-amp by using the cap. I would probably simply add a space for a .4" or .6" lead spaced cap(MKT etc).
Right now you could use a cap, but you would have to P2P to the pot or on the board. I think it makes things a little cleaner for those who want the safety of the input cap.
What do you think?
Cheers,
Russ
Hi Russ,
Do it. 🙂
More flexibility is good, it won't impact the performance or construction for those who don't need the caps.
Michael
Do it. 🙂
More flexibility is good, it won't impact the performance or construction for those who don't need the caps.
Michael
Providing the extra space for a cap will only make the board bigger and therefore more expensive. If one uses a cap with leads it can be easily soldered between the RCA connector and attenuator and save on two extra solder joints this way. This is just my opinion on the subject.
Cheers
P.S: Really need to finish those boards
Cheers
P.S: Really need to finish those boards
maf_au said:
GeWa said:
He he he, funny thing is at different times I agree with both of you!
😀I think I could do it without add much space, just a few mm. I think the price will still be pretty low.
Cheers!
Russ
Russ,
My vote is to put it on the board. Won't add that much to cost for a board this size. If someone does not like the extra connections, they can run the cap off board and solder it into the second hole.
Craig
My vote is to put it on the board. Won't add that much to cost for a board this size. If someone does not like the extra connections, they can run the cap off board and solder it into the second hole.
Craig
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