Re: my findings
Hi Rudi, I trust you meant the LM318 not 317.
I had talked about this with Brian Donegan (The different pin out of the 318) when I first built my Rev C prototype. It does indeed make it quite impractical to try any other opamp for RevC. For Rev A just about any solid single opamp will work, but a high slew rate is desirable, bandwidth, while not to be neglected, is not as imprtant, 7-8mhz or more should be just fine. One nice feature of the 318 is its great slew rate, and I think its an important part of why things sound so good.
There are a few other opamps that use pin 8 like the LM318 does, but non of them are really the same sort of opamp.
I would agree that exchanging the LM318 for an opa627(or 637 for that matter) in a REV A circuit has no sonic benefit, though if you are the sort who feels better when you throw more money at an amp you may like it better.
I do like the REV C better than Rev A now that I have as many or more hours listening to Rev C.
Rev C passes the "long term listenability" test, you simply don't get fatigued listening to it for hours on end. Rev A is also very good for long sessions, but C just seems better.
The biggest win for the C is more precise soundstage. You really almost have to do a direct A/B test to detect it (which I have) but it is real.
Good work Rudi!
And thank you for the kind words!
Mauro, thanks to you for such a marvelous and fresh approach to the chip amp.
Now back outside to fish (I am on vacation)
Cheers!
Russ
rudi said:
Hi Rudi, I trust you meant the LM318 not 317.
I had talked about this with Brian Donegan (The different pin out of the 318) when I first built my Rev C prototype. It does indeed make it quite impractical to try any other opamp for RevC. For Rev A just about any solid single opamp will work, but a high slew rate is desirable, bandwidth, while not to be neglected, is not as imprtant, 7-8mhz or more should be just fine. One nice feature of the 318 is its great slew rate, and I think its an important part of why things sound so good.
There are a few other opamps that use pin 8 like the LM318 does, but non of them are really the same sort of opamp.
I would agree that exchanging the LM318 for an opa627(or 637 for that matter) in a REV A circuit has no sonic benefit, though if you are the sort who feels better when you throw more money at an amp you may like it better.
I do like the REV C better than Rev A now that I have as many or more hours listening to Rev C.
Rev C passes the "long term listenability" test, you simply don't get fatigued listening to it for hours on end.
Rev A is also very good for long sessions, but C just seems better.The biggest win for the C is more precise soundstage. You really almost have to do a direct A/B test to detect it (which I have) but it is real.
Good work Rudi!
And thank you for the kind words!
Mauro, thanks to you for such a marvelous and fresh approach to the chip amp.
Now back outside to fish (I am on vacation)
Cheers!
Russ
Hi Russ. you are absulately right. LM318. could be a serious typo and somebody might blow something up.
I am glad to hear you confirm my findings regarding the op-amps. i just had to try it to satisfy my curiosity.
well i am glad the changes on C are for the better. nothing like a system that fatigues you..
well it is winter here (or suppose to be) and i have to work
cheers
Rudi
I am glad to hear you confirm my findings regarding the op-amps. i just had to try it to satisfy my curiosity.
well i am glad the changes on C are for the better. nothing like a system that fatigues you..
well it is winter here (or suppose to be) and i have to work
cheers
Rudi
bg40403 said:
I have only used con 3 to power a diodes. Used two 3.5 volt 20 ma in series. Looks about right, it is not too bright.
Some of these diodes with do permanent eye damage if cranked up too high.
You are on your own with the fan, it looks to have the same voltage without the 6.8K current limiting resistor.
George
bg40403 said:
Ed,
For conn2 the speaker protection circuit will trip (and thus no sound) very easily with most 12V fans, so really unless you have a very low current drawing fan it will not work. I have tried.
Conn3 work perectly for the LED, though I found 6.8K results in a very bright LED, so I went with 12K which works great with the blue super-brights I use.
Cheers!
Russ
I think for fan use, you need either a really low current coil relay, or drive the base of a transistor for more current.
Russ, on the RevC, perhaps you could add another small transistor for driving a fan or other higher current load? Yes, I am causing trouble.
PS: I don;t think a fan is really needed unless your heatsink if very very small.
-b
Russ, on the RevC, perhaps you could add another small transistor for driving a fan or other higher current load? Yes, I am causing trouble.
PS: I don;t think a fan is really needed unless your heatsink if very very small.
-b
Actually I am just omitting that "feature" as I think in reality a cheap 12V trafo is like $4 and you only need one.BrianDonegan said:
Your PS is right on the point. I can't imagine why anyone would "need" a fan, and if they where building such enclosure I am sure they would plan for a fan.
So unless I hear a pretty good case for the fan circuit, I am not sure why I should add it. Since it will likely be just waste.
What do you think?
Cheers!
Russ
If there is enough demand I suppose it would be easy enough to just run a couple of traces from the ~15V supply to the SP circuit prior to the SP circuit (so that it does not trip the relay), but that will likely be too hot for most fans. We could also run a second 12V shunt regulator or a 7812 or something to get 12V, but that seems like a lot of fuss for a dang fan.
Cheers!
Russ
Cheers!
Russ
How could someone just wire in a 12V wall wart to mains to power a 60mm computer cpu fan? A computer HSF is alot more affordable than a $20.00 heat sink from some guy in Michigan.
I'm amazed at some of the GC cases around here. Are there any advantages to one material over another ? Has anyone ever seen a gainclone in plexiglass ? Is there a prefered RCA jack or Speaker terminal thats a great buy ? Is there a prefered jumper wire and routing or looming system ? a Best place for the trafo ?Can I use a mains plug from an old computer supply ?
I've read Nuuk's FAQ but am so new to DIY electronics I couldn't make sense of it all ? I was thinking of building in the back of my 1/2din equalizer with aluminum angle and socket head cap screws; would this work ?
Ok, I am getting ready with the RevC kits. They will include everything you need to stuff the boards, RevA or RevC. They will be a bit more than the RevA kits were for two reasons:
1) I don't feel like loosing money again (almost broke even, but not quite)
2) With the seperate boards, there is a little bit of parts duplication (what once was one, is now two, etc).
I am going to ballpark it at $60 per stereo pair ($30 per channel).
Differences from RevA Kit:
- All EL caps are Panasonics instead of Nich. Digikey has better availability with them than Mouser with the Nich's.
- The red-hot 1W resistors from the first kit are now 2W Xicons. R14 is now a Xicon, but still 1W. These are larger and should be cooler.
- Yageo ceramic 5W resistor is now a vertical Xicon 7W to fit the board.
New (RevC) additions:
- new caps are all Panasonic
- except 22pF and 10pF caps, which are Waldom Silver Mica. Willing to entertain other ideas here, as these are over a dollar each. Didn't want to pick cheapo ceramics, as I knew it would be unpopular (I used cheapo Ceramics on mine and it sounds fine FWIW)
- Relay is now an Omeron G5LE-14-DC24 and you get two, one per board
- I will include non-polar pin headers
- other stuff, like now there are twice as many transistors, etc
Question: do people want sockets for the LM318s? Since there isn't much point in swapping opamps, maybe best to just solder them in.
Give me your feedback.
Also, I am trying to gauge interest in kits. Not taking orders yet. If you think you might be interested, drop me an email at:
RevCKit at gmail.com (replace at with @)
Won't be considered a committment, just trying to figure out how many I should be ordering.
Thanks!
1) I don't feel like loosing money again (almost broke even, but not quite)
2) With the seperate boards, there is a little bit of parts duplication (what once was one, is now two, etc).
I am going to ballpark it at $60 per stereo pair ($30 per channel).
Differences from RevA Kit:
- All EL caps are Panasonics instead of Nich. Digikey has better availability with them than Mouser with the Nich's.
- The red-hot 1W resistors from the first kit are now 2W Xicons. R14 is now a Xicon, but still 1W. These are larger and should be cooler.
- Yageo ceramic 5W resistor is now a vertical Xicon 7W to fit the board.
New (RevC) additions:
- new caps are all Panasonic
- except 22pF and 10pF caps, which are Waldom Silver Mica. Willing to entertain other ideas here, as these are over a dollar each. Didn't want to pick cheapo ceramics, as I knew it would be unpopular (I used cheapo Ceramics on mine and it sounds fine FWIW)
- Relay is now an Omeron G5LE-14-DC24 and you get two, one per board
- I will include non-polar pin headers
- other stuff, like now there are twice as many transistors, etc
Question: do people want sockets for the LM318s? Since there isn't much point in swapping opamps, maybe best to just solder them in.
Give me your feedback.
Also, I am trying to gauge interest in kits. Not taking orders yet. If you think you might be interested, drop me an email at:
RevCKit at gmail.com (replace at with @)
Won't be considered a committment, just trying to figure out how many I should be ordering.
Thanks!
BrianDonegan said:
What EL caps did you replace with Panasonics? What type?
BrianDonegan said:
- What Panasonic types? Polypropylene?
- Most people seem to forget polystyrenes and many times they are better than silver mica. Xicon has a whole line of them: they are much cheaper than silver mica. Certainly no need to go for ceramics. But even if you go for mica, Dubilier types can be quite competitive.
BrianDonegan said:
A good point indeed.
Carlos E. Martínez