Nice job man. 
Very nice match for the kooka. 😀
Great work on the HS, cool idea.
Now the important question. How do you like it?
Cheers!
Russ
Very nice match for the kooka. 😀Great work on the HS, cool idea.
Now the important question. How do you like it?
Cheers!
Russ
Member
Joined 2003
So far, loving it. Subtly stronger midrange over the Rev.A, but I am also using different coupling caps (Solen MKP), so that could be part of it.
I was an idiot when I hooked everything up to my test speaker (Tang-Band 15W 3" driver), I plugged the power cord into the preamp, but the RCA cable I just went straight from my CD player to the amp. Blared some Big Sugar through that little speaker as loud as the amp possibly could for about 5 seconds. I'm suprized that little speaker is still alive.
I was an idiot when I hooked everything up to my test speaker (Tang-Band 15W 3" driver), I plugged the power cord into the preamp, but the RCA cable I just went straight from my CD player to the amp. Blared some Big Sugar through that little speaker as loud as the amp possibly could for about 5 seconds. I'm suprized that little speaker is still alive.
Nice amp and layout Dcibel. Room for two T/F even, although one works fine for me.
Give it time to run in - you'll get some improvement.
Audie.
Give it time to run in - you'll get some improvement.
Audie.
Hello, long time lurker, first post. I finally ordered a RefC kit, and while I wait for it to arrive I'm starting to get the missing parts.
I have some 12V, 150VA toroidals, and I think that connecting them in series of 2 will give me 24V, 300VA. Am I right?
I have some 12V, 150VA toroidals, and I think that connecting them in series of 2 will give me 24V, 300VA. Am I right?
Member
Joined 2003
You are right, however the Mauro amp requires +-24V, not +-12V. You need a 48VCT transformer, or a 24V + 24V dual secondary transformer, or with your method you will require two 24V single secondary transformers.
Uh, right, I forgot the center tap. Quantity is not really a problem, I can get them for about 4 US$ each, much cheaper than a regular transformer. For a prototype, they'll do (I hope).
Hi,Mauro!
I see the electric circuit of your LM3886, liking your this kind of DIY spirit very much, making the one do simple LM3886 extraordinary electric circuit, I respect and admire very much!!
Excuse me, have new electric circuit of design to come out recently?I also want use you of the electric circuit come to DIY, can you help me?
Thanks!
DIY fancier:Vincent Lee
I see the electric circuit of your LM3886, liking your this kind of DIY spirit very much, making the one do simple LM3886 extraordinary electric circuit, I respect and admire very much!!
Excuse me, have new electric circuit of design to come out recently?I also want use you of the electric circuit come to DIY, can you help me?
Thanks!
DIY fancier:Vincent Lee
Something I read kept haunting me, so sorry for the delayed response.
Are we to understand that you will be removing the gain/buffer stage infront of the actual chipamp in the new version?, I can't find the post were I got this impression from now, but yeah, as I said, it keeps bugging me when I am trying to listen to music instead (sorry, major addictive personality disorder).
Oh and Brian, If you haven't tried the REV C with Fran'z valve buffer, you are missing out, I thought the first tube I tried it with was good, but it is plain horrible compared to what I'm hearing now. Impossible to believe that 4 resistors and a valve can sound that good... The first tube gave a slight memory of old valve hardwarde sound, but the second tube I tried sounds like, erm , well, silicon, just better!🙂
Are we to understand that you will be removing the gain/buffer stage infront of the actual chipamp in the new version?, I can't find the post were I got this impression from now, but yeah, as I said, it keeps bugging me when I am trying to listen to music instead (sorry, major addictive personality disorder).
Oh and Brian, If you haven't tried the REV C with Fran'z valve buffer, you are missing out, I thought the first tube I tried it with was good, but it is plain horrible compared to what I'm hearing now. Impossible to believe that 4 resistors and a valve can sound that good... The first tube gave a slight memory of old valve hardwarde sound, but the second tube I tried sounds like, erm , well, silicon, just better!🙂
We are not making any substantive changes to the circuit in the new version. Just added space for discrete rectifier diodes, a bigger input cap (now including a 1uF Wima MKP10 as input cap), and improved the traces.
If I find some time, I'll try the valve buffer. Seems easy enough.
If I find some time, I'll try the valve buffer. Seems easy enough.
Hi Nordic,Nordic said:
This advice is not really directly only to you, and I want you to know I think you are a very cool and nice guy.
Just to help you understand the circuit, there never was a buffer. The LM318 in MyREF is not a buffer at all. This is absolutely critical to understand. This is a misconception that many people seem to have and it is actually quite understandable.
You cannot do a MyREF amp without the second opamp as it is. When you get a chance read through the technical documentation here:
http://www.diyaudio.com/forums/showthread.php?postid=815025#post815025
You will see what I mean.
One other misconception which even a member of the forum who people consider an audio demi-god around here held for the longest time, is that the input impedance is 3.3K. It of course is not (as Mauro pointed out early on). He too made lot of statements about the circuit without even understanding how the input stage worked.
The input impedance is in fact 100K. I only point this out because that same sort of misconception leads to all sorts of misunderstanding about how the amp works and leads to ideas that are so far off base that useful conversation about them is really impossible.
So if you (actually anyone who cares) have a spare half hour or so read through the document and anything you don't understand (which was a lot for me until recently) go google it, or search the forums. And please, have your demi-god filter on full tilt. One good thing to remeber when you are learning any sort of engineering is to respect the engineers that went before you, but to treasure more the changeless facts. I know from my perspective (I have only been doing this 1 year) you will get the most out of this hobby when you really try to understand (at least as best you can) the engineering behind the designs, and in this case Mauro has laid it all out for us.
Once again, this is only meant to be encouragement.
Cheers!
Russ
Yeah, I admit I was not 100% sure how it worked thats why I used the slash... but my understanding was also that it was critial to the whole amp's implementation. 😎
Finally got all the parts and tried to build one channel which does not work 🙂
The relay clicks, the lm3886 gets real hot after a few seconds and I get no sound.
Has anybody posted a step-by-step mounting guide with checkpoints for newbies (something like solder this and this, measure this and it should read xxxV)?
I read this monster thread entirely but I couln't find something like that.
Any tips on debugging ?
J.
The relay clicks, the lm3886 gets real hot after a few seconds and I get no sound.
Has anybody posted a step-by-step mounting guide with checkpoints for newbies (something like solder this and this, measure this and it should read xxxV)?
I read this monster thread entirely but I couln't find something like that.
Any tips on debugging ?
J.
Nidhogg,
here it is - in italian, but that should not be a big problem for You.. 😉
http://www.audiofaidate.it/sito.asp?goto=my_ref
Ciao, George
here it is - in italian, but that should not be a big problem for You.. 😉
http://www.audiofaidate.it/sito.asp?goto=my_ref
Ciao, George
Hosed!
Check rail voltages, output offset voltage, and such. The clicking relays sez you are getting power to that circuit and low dc on offset.
First recheck all the components, proper placement, and orientation. Then redo all solder connections.
It has to be either a part in the wrong position, bad solder joint, or power wiring.
Is this the mono board set or the older stereo version? The stereo version required several wire links because those are single sided boards.
George
Nidhogg said:
Check rail voltages, output offset voltage, and such. The clicking relays sez you are getting power to that circuit and low dc on offset.
First recheck all the components, proper placement, and orientation. Then redo all solder connections.
It has to be either a part in the wrong position, bad solder joint, or power wiring.
Is this the mono board set or the older stereo version? The stereo version required several wire links because those are single sided boards.
George
Hi,
It's the rev C mono board, single sided version that Russ posted as PDF files a while ago.
I was checking the supply voltage on the LM3886 yesterday and I shorted something when measuring so now I guess the LM is pretty much useless (there are bad burn marks on 2 of the pins ...).
Anyway I posted some pictures here : http://stup.org/MyRefC/.
Sorry, I can't get a clear closeup shot of the solder side (crappy camera).
Before I shorted the lm I got this far :
The trafo wiring looks like this
I wired black and orange together to PGND, red to AC1 and yellow to AC2. Is that right ?
I measured about 26V out of the trafo per rail with no load. At the diode bridge output I got something like 55V (can't remember the exact value. I measured about 60V as input to the LM (pins 1 and 4 I think) just before I shorted the pins 🙁
I'll try to build another channel, is there a way to build it step by step and make sure each step is working ? Like power supply stage first, op amp next , lm last for example ?
The italian site shows how to solder the components but I don't think there are checkpoints with measurements so that I can validate it step by step.
Thanks for your help !
J.
It's the rev C mono board, single sided version that Russ posted as PDF files a while ago.
I was checking the supply voltage on the LM3886 yesterday and I shorted something when measuring so now I guess the LM is pretty much useless (there are bad burn marks on 2 of the pins ...).
Anyway I posted some pictures here : http://stup.org/MyRefC/.
Sorry, I can't get a clear closeup shot of the solder side (crappy camera).
Before I shorted the lm I got this far :
The trafo wiring looks like this
An externally hosted image should be here but it was not working when we last tested it.
I wired black and orange together to PGND, red to AC1 and yellow to AC2. Is that right ?
I measured about 26V out of the trafo per rail with no load. At the diode bridge output I got something like 55V (can't remember the exact value. I measured about 60V as input to the LM (pins 1 and 4 I think) just before I shorted the pins 🙁
I'll try to build another channel, is there a way to build it step by step and make sure each step is working ? Like power supply stage first, op amp next , lm last for example ?
The italian site shows how to solder the components but I don't think there are checkpoints with measurements so that I can validate it step by step.
Thanks for your help !
J.