Hi,
I am also new on this and have also been reading a lot trying to decide which configuration to build.
I agree that the LM3886 chip seems to be preferred as it handles speakers with lower impedance and less sensitive. I have single driver jordans JX92S (maybe with BSC): 6 Ohms and down to 85db and that's why I want to use the LM3886.
My idea is to start from the "begining" by using the very basic schematics of the original 47 Lab Gaincard (but using the LM3886 instead of the LM3857) as "translated" by Mick F (which includes the basic PSU without capacitors):
http://dogbreath.de/Chipamps/GainCardCopy/GainCardCopy.html
I do not intend to make the design as compact as Mick F but to start by doing what was recommended above by seventenths (thanks 7/10 for this simple good idea) using a proto-board following almost physically the schematic. This will 1) allow me to learn more than using a PCB 2) it will be much cheaper and 3) and will allow more room for future improvements to the configuration and layout. It might end up super compact and buffered, with a snubberized PSU, etc, etc who knows!
Mick F includes the part list (only 9 components like the original), so it seems seems like an easy project to start
I hope this thread keeps focused on the basics of chipamp building for newbees or as said before: '50 watt per channel Dual Dummies"
Thanks in advance to those willing to help or keep helping
Regards
Antonio
I am also new on this and have also been reading a lot trying to decide which configuration to build.
I agree that the LM3886 chip seems to be preferred as it handles speakers with lower impedance and less sensitive. I have single driver jordans JX92S (maybe with BSC): 6 Ohms and down to 85db and that's why I want to use the LM3886.
My idea is to start from the "begining" by using the very basic schematics of the original 47 Lab Gaincard (but using the LM3886 instead of the LM3857) as "translated" by Mick F (which includes the basic PSU without capacitors):
http://dogbreath.de/Chipamps/GainCardCopy/GainCardCopy.html
I do not intend to make the design as compact as Mick F but to start by doing what was recommended above by seventenths (thanks 7/10 for this simple good idea) using a proto-board following almost physically the schematic. This will 1) allow me to learn more than using a PCB 2) it will be much cheaper and 3) and will allow more room for future improvements to the configuration and layout. It might end up super compact and buffered, with a snubberized PSU, etc, etc who knows!
Mick F includes the part list (only 9 components like the original), so it seems seems like an easy project to start
I hope this thread keeps focused on the basics of chipamp building for newbees or as said before: '50 watt per channel Dual Dummies"
Thanks in advance to those willing to help or keep helping
Regards
Antonio
seventenths said:Antonio,
I just posted a 3886, dirt simple implementation in the chip amp photo gallery. When my camera battery is charged, I'll post a shot of my first breadboard effort and if I can find it, a VERY simple "dead bug" that was my first test effort.
I predict success
7/10
7/10
Thanks. Yes, I saw it. It looks very simple. Could you post a photo of the other side of the board?. Which schematics did you use?
Antonio
seventenths said:Antonio,
Sure thing... just waiting on that camera battery.
The 3886 is based on a Carlos FM schematic pulled from "Decibel Dungeon".
7/10
Thanks 7/10
Cool! that's also in my shortlist because I could keep going and implement step by step Carlos FM's snubberized PSU and also build his buffer or jfet preamp, which apparently are very good.
Look forward to see the photo later.
Antonio
Here's a quick sketch to give you a head start.
Supplies shown:
LM3875TF
Experimenter's board (phenolic with individual round pads)
hook-up wire
pack of 1/4w resistors
A 1w 4 ohm (3.9r) resistor for speaker zobel
200nF or 100nF polyester cap for speaker zobel
22uF Mallory SEK 200v ecap for position CI *note1
3x 4.7uF Mallory SEK 250v ecap *note2
4x 4700uF low-esr 50v or 63v ecap *note3
2x 470uf low-esr 50v ecap *note4
2x 100nF ceramic caps
A block bridge rectifier unit *note5
4x 10nF ceramic caps
Not shown:
transformer
heatsinks
cables
Notes:
1) Nichicon KZ 22uF 50v is another good option; A 47nF polyester cap can be added (paralleled) to give more "air" effect if desired.
2) Elna Cerefine 4.7uF 50v is another good option; although any capacitor can block DC, this component selection is more art than science. A 47nF polyester cap can be added (paralleled) to give more "air" effect if desired.
3) You can parallel additional 100nF or 47nF polyester to a pair of the 4700uF power caps, preferably closer to the bridge rectifier.
4) EDIT: You can use the 470uF shown although 220uF or 330uF are other options, and these options will sound different. Personally, I'd just choose the option that is most pleasant.
5) Although a popular "known good" bridge block is shown, it is perhaps safer to choose a similar option with an all-plastic body. To support a center tap transformer, the bridge block is "ringed" in 10nF ceramic (or polyester) caps, looking much like a propeller.
Additional note: Parts Express carries Tracon polyester, although most economy mylar / polyester will do.
This sketch is to help give an idea on how to layout for an E-board project. Dry fit components first. The power ground wire should be twice as thick as any other wire.
Supplies shown:
LM3875TF
Experimenter's board (phenolic with individual round pads)
hook-up wire
pack of 1/4w resistors
A 1w 4 ohm (3.9r) resistor for speaker zobel
200nF or 100nF polyester cap for speaker zobel
22uF Mallory SEK 200v ecap for position CI *note1
3x 4.7uF Mallory SEK 250v ecap *note2
4x 4700uF low-esr 50v or 63v ecap *note3
2x 470uf low-esr 50v ecap *note4
2x 100nF ceramic caps
A block bridge rectifier unit *note5
4x 10nF ceramic caps
Not shown:
transformer
heatsinks
cables
Notes:
1) Nichicon KZ 22uF 50v is another good option; A 47nF polyester cap can be added (paralleled) to give more "air" effect if desired.
2) Elna Cerefine 4.7uF 50v is another good option; although any capacitor can block DC, this component selection is more art than science. A 47nF polyester cap can be added (paralleled) to give more "air" effect if desired.
3) You can parallel additional 100nF or 47nF polyester to a pair of the 4700uF power caps, preferably closer to the bridge rectifier.
4) EDIT: You can use the 470uF shown although 220uF or 330uF are other options, and these options will sound different. Personally, I'd just choose the option that is most pleasant.
5) Although a popular "known good" bridge block is shown, it is perhaps safer to choose a similar option with an all-plastic body. To support a center tap transformer, the bridge block is "ringed" in 10nF ceramic (or polyester) caps, looking much like a propeller.
Additional note: Parts Express carries Tracon polyester, although most economy mylar / polyester will do.
This sketch is to help give an idea on how to layout for an E-board project. Dry fit components first. The power ground wire should be twice as thick as any other wire.
Attachments
Peter Daniel said:
Hi Peter!! (hey folks, his audiosector.com products are high quality and durable too).
Questions (2) in regards to Audiosector LM3875 Dual Mono Kit:
What do you think about a pair of these: http://www.alliedelec.com/Search/ProductDetail.asp?SKU=967-7475 dual-secondaries 48v transformers, as a nice compact option? I've been pleased with their center tap version, but haven't tried the dualie version (link).
Do you offer, or plan to offer, a preamplifier kit to match the LM3875 power amplifier kits? If so, that would be really helpful (edit) addition to most chipamp projects.
Thanks!
For beginners I'd seriously recommend reading everything you can at decibel dungeon:
http://myweb.tiscali.co.uk/nuukspot/decdun/gaincloneindex.html#top1
It covers some really good stuff and doesn't assume much prior knowledge. It really helped me building my amp. (thanks Nuuk!)
http://myweb.tiscali.co.uk/nuukspot/decdun/gaincloneindex.html#top1
It covers some really good stuff and doesn't assume much prior knowledge. It really helped me building my amp. (thanks Nuuk!)
Breaking silence only to comment. I've read another 6 hours today. It's nothing I haven't read before in the last year. I wish I could have put a link to all I observed in a multitude of designs that I believed would compose an anally retentive gainclone that an 8 year old could build because I do believe thats possible if they were properly laid out. They are not in my opinion.
I have yet to encounter anywhere a single site that takes you from start to finish on how to build a gainclone pictorially along with written instructions as to what it is you are doing and why you are doing it.
Generally speaking even photos have you squinting to try and figure out just exactly what is being soldered to what. Thats only part of the reason I stated a preference to point to point.
I believe, but won't speak for him, that Gychangs quest is to finally make this simple enough that an actual 'newbee' can build one that works . Dogbreaths is one , if not , the simplest I've seen. Mark Houstons design at D.D. ( baking pan) is so huge a novice solderer ought to be able to handle it . The problem is that if you look at either schematic and then look at their photos and you don't have a background in electronics you are still totally lost. Wondering out loud why you can't cut off unneeded leads on 3886 chip on dogbreaths design just to get them out of the way? Wondering out loud why resistors are looped as closely as they are to other chip leads when they appear to end up at both the electrolytics and star ground anyway? Seems to me only reason for doing such was desire for a compact amp and it would have been a much easier build for a novice to have spread out the design. Shorter signal paths are cleaner but a difference of inches is not critical in this application.
In the time ( more than I can count) in the last 18 months I read on these things , it seems to me all was inspired by the compactness of the 41z. Rather than rethink it practically for purpose of ease of build everyone simply thought to copy it. That concept won't work well for a newbee.
I'm betting there are a whole bunch of electronically illiterate people here on list that want to build a gainclone that don't want to invest $80 - $100 for a kit they aren't sure will work when they've never handled a soldering iron and need to purchase that as well.
I personally don't see these things as tough to do. I don't see kits as overpriced either when you consider the profit the manufacturer needs to make. However, I've read a few of their published manuals and they are not very good. If they won't answer e-mails pre-purchase you know they won't be there for customer support when you don't understand something.
Realized through reading today that the Apex JR available 3886 chip is not a good choice should consensus be 3886. I like Apex JR, no problem there. Found a couple of other good sources for some other parts as well as better chips.
Greg - Apologies for butting in , still your thread and your decisions , I just got excited about getting something going and a bit frustrated after all I'd read.
I don't want to leave anyone on a discouraging note. I'd like to see a bunch of people who have tryed and failed or were afraid to try see an actual example of a step by step easy to build low cost gain clone with a very high 1st time build success rate for total beginners. That takes some planning.
Bluto
I have yet to encounter anywhere a single site that takes you from start to finish on how to build a gainclone pictorially along with written instructions as to what it is you are doing and why you are doing it.
Generally speaking even photos have you squinting to try and figure out just exactly what is being soldered to what. Thats only part of the reason I stated a preference to point to point.
I believe, but won't speak for him, that Gychangs quest is to finally make this simple enough that an actual 'newbee' can build one that works . Dogbreaths is one , if not , the simplest I've seen. Mark Houstons design at D.D. ( baking pan) is so huge a novice solderer ought to be able to handle it . The problem is that if you look at either schematic and then look at their photos and you don't have a background in electronics you are still totally lost. Wondering out loud why you can't cut off unneeded leads on 3886 chip on dogbreaths design just to get them out of the way? Wondering out loud why resistors are looped as closely as they are to other chip leads when they appear to end up at both the electrolytics and star ground anyway? Seems to me only reason for doing such was desire for a compact amp and it would have been a much easier build for a novice to have spread out the design. Shorter signal paths are cleaner but a difference of inches is not critical in this application.
In the time ( more than I can count) in the last 18 months I read on these things , it seems to me all was inspired by the compactness of the 41z. Rather than rethink it practically for purpose of ease of build everyone simply thought to copy it. That concept won't work well for a newbee.
I'm betting there are a whole bunch of electronically illiterate people here on list that want to build a gainclone that don't want to invest $80 - $100 for a kit they aren't sure will work when they've never handled a soldering iron and need to purchase that as well.
I personally don't see these things as tough to do. I don't see kits as overpriced either when you consider the profit the manufacturer needs to make. However, I've read a few of their published manuals and they are not very good. If they won't answer e-mails pre-purchase you know they won't be there for customer support when you don't understand something.
Realized through reading today that the Apex JR available 3886 chip is not a good choice should consensus be 3886. I like Apex JR, no problem there. Found a couple of other good sources for some other parts as well as better chips.
Greg - Apologies for butting in , still your thread and your decisions , I just got excited about getting something going and a bit frustrated after all I'd read.
I don't want to leave anyone on a discouraging note. I'd like to see a bunch of people who have tryed and failed or were afraid to try see an actual example of a step by step easy to build low cost gain clone with a very high 1st time build success rate for total beginners. That takes some planning.
Bluto
Hi Valleyman -
I hope you can elaborate cause as you can see I've referenced D.D. twice in my postings and I really like that site , was one of the best I discovered over a year ago but I still don't see a simple start to finish build for a beginner over there yet. Alot of theory by many who have built as well as plenty on 'hot rodding ' amps and tons of 'tips' but nothing from A-Z newbee builds unless I've missed it somehow.
Thanks
Bluto
I hope you can elaborate cause as you can see I've referenced D.D. twice in my postings and I really like that site , was one of the best I discovered over a year ago but I still don't see a simple start to finish build for a beginner over there yet. Alot of theory by many who have built as well as plenty on 'hot rodding ' amps and tons of 'tips' but nothing from A-Z newbee builds unless I've missed it somehow.
Thanks
Bluto
Bluto said:
We could manufacture such a site.
EDIT: But, my writing skill is a sort of caveat.
The kits, such as Audiosector, are extremely durable, and if you have the three tools (FLUX!, soldering iron, desoldering iron), then those work, pretty much instantly.
However, if you're looking for a problem, its that there's scarce information provided about preamplifier/dc blocking needs.
Back on track at last. . .
The first decision is going to be: What chip?
In my opinion, LM3875TF (TF!!) is the safest and easiest option because the "TF" version of LM3875 is insulated so that it doesn't put voltage on the heatsink. Despite 11 pins, it has only 5 connections. See photo above. It also has a wider-than-usual voltage tolerance.
The problem of how to plug it in. . . is solved.
Here is my "Ladderback" power supply. You may use it for non-commerial, diy projects. This power supply would be even easier with a "block" one-piece bridge rectifier. But, you can see that its pretty easy as it is.
You can use four of 4700uF instead of eight 2200uF, either way, at your option.
Click photo below.
Attachments
I was actually going to do such a guide on DD but then I started writing/reviewing for TNT and became a question of finding the time. I also reckoned that the chip amp craze was waining and asked myself if it a sensible use of (a lot of) my time to create such a guide for a comparative few. Visiting this forum though indicates ther eis still a healthy interest in building these amps!
In fairness, it is not just the GC pages of DD that should be read. There is other stuff there on the basics like soldering and getting started. I have absolutely no training in electronics, and I built my first GC's and got them working first time. I had done a bit of DIY hi-fi before them though so knew what a resistor looked like, and how to solder it. But I read and read until I did understand the circuit.
As regards the compactness of the circuit, I agree it doesn't need to be ultra compact if it is going to be housed in a shielded eg metal, enclosure . Otherwise (and I prefer a non-metal enclosure) it is better to keep those connections as short as possible.
Finally, from the emails sent to me via DD, I can see that a large number of complete newbies have successfully built chip amps from the information provided on my site, and on the various forums.
Hi DWB -
The chip I was going to suggest based upon further reading was the 3886 TF. Apex only carries the T. I've read the 3875 has a warmer sound to it and some claim the 3886 is a bit too bright . My preference towards the 3886 was it's higher wattage capabilities and the fact that it also could be used in a 5 pin configuration. I am considering an FR line array in the future and that extra power would have been nice. My suggestions were selfish for those 2 reasons as well as the fact that my front mains aren't very efficient and the extra wattage would be helpful there as well. I have read testimony that the 3886 supposedly has a better mid. I have no experience. I agree with you that 1st decision is what chip and mentioned such to Greg.
Just realized earlier tonight that Mark Houston's design that I've referred to is called 'The Synergy'. I hadn't been there for ages either. Maybe it will ring a bell with people now. He uses a 3875.
I'm just tossing thoughts here, Gychang hasn't chimed in and I've told him I'm following his lead. C'mon Greg, what's more important - Medicine or Audio? I'm sick or wouldn't be up at this hour, c'mon over and take care of me and work on this at same time !
Manufacturing such a site was very much on my mind, I've been pretty irritated it didn't exist. Thank You for bringing it up. I'd like to see such to the point of being infantile as well as articulate for the educated. Quality photos, arrows and numbers. Mentioned same to Greg. A fairly good example would be the 'mod' sites for the old Sonic T - amps. Too bad no sooner than a couple guys put those together Sonic discontinued them.
I've intently read all you've said. You know your stuff. I can't read the notes but I know the Song well enough to hum. Does that make sense? You've already pretty much laid out a virtual roadmap here with all you've provided. Despite not being able to understand a great deal of it it's good to know you're here and I hope you stay interested, you're more than needed.
I agree as well regards pre-amp but don't understand DC blocking at all so an expert as yourself is needed in this quest. Stereo, dual mono, how many outs, etc., etc. Lots of questions. All need to be factored into design of easy to build amp so it integrates in the event builders desire to upgrade. This is part of reason I gave up last year. What I wanted just wasn't there, at same time I questioned why not?
I'm not getting a photo here... my computer? The fact that you design puts you way ahead of this guy. I'll check later and see if it shows up.
I'm good to go with whatever Gychang wants to do. Will help any way I can.
Bluto
The chip I was going to suggest based upon further reading was the 3886 TF. Apex only carries the T. I've read the 3875 has a warmer sound to it and some claim the 3886 is a bit too bright . My preference towards the 3886 was it's higher wattage capabilities and the fact that it also could be used in a 5 pin configuration. I am considering an FR line array in the future and that extra power would have been nice. My suggestions were selfish for those 2 reasons as well as the fact that my front mains aren't very efficient and the extra wattage would be helpful there as well. I have read testimony that the 3886 supposedly has a better mid. I have no experience. I agree with you that 1st decision is what chip and mentioned such to Greg.
Just realized earlier tonight that Mark Houston's design that I've referred to is called 'The Synergy'. I hadn't been there for ages either. Maybe it will ring a bell with people now. He uses a 3875.
I'm just tossing thoughts here, Gychang hasn't chimed in and I've told him I'm following his lead. C'mon Greg, what's more important - Medicine or Audio? I'm sick or wouldn't be up at this hour, c'mon over and take care of me and work on this at same time !
Manufacturing such a site was very much on my mind, I've been pretty irritated it didn't exist. Thank You for bringing it up. I'd like to see such to the point of being infantile as well as articulate for the educated. Quality photos, arrows and numbers. Mentioned same to Greg. A fairly good example would be the 'mod' sites for the old Sonic T - amps. Too bad no sooner than a couple guys put those together Sonic discontinued them.
I've intently read all you've said. You know your stuff. I can't read the notes but I know the Song well enough to hum. Does that make sense? You've already pretty much laid out a virtual roadmap here with all you've provided. Despite not being able to understand a great deal of it it's good to know you're here and I hope you stay interested, you're more than needed.
I agree as well regards pre-amp but don't understand DC blocking at all so an expert as yourself is needed in this quest. Stereo, dual mono, how many outs, etc., etc. Lots of questions. All need to be factored into design of easy to build amp so it integrates in the event builders desire to upgrade. This is part of reason I gave up last year. What I wanted just wasn't there, at same time I questioned why not?
I'm not getting a photo here... my computer? The fact that you design puts you way ahead of this guy. I'll check later and see if it shows up.
I'm good to go with whatever Gychang wants to do. Will help any way I can.
Bluto
Thake a look at http://electronics.dantimax.dk/Kits/Preamps_-_poweramps/10980564722.html
This is an almost complete set. Ad a trannie and some in- and outputs....
Voila !
Did 4 of them myself for an extended surroundset. Very easy and very effective.
Good luck.
This is an almost complete set. Ad a trannie and some in- and outputs....
Voila !
Did 4 of them myself for an extended surroundset. Very easy and very effective.
Good luck.
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