My first DIY attempt!

[indialogue]

Hi guys, just wanted to share my second build with you all. Its a 3-channel Cmoy amplifier, built from a kit procured from Fred's Amplifiers a few weeks back. The best thing about this kit is that it actually fits inside an Altoids tin, unlike the previous kit which claimed to be an Altoids fit, but turned out otherwise

I made one significant change in this soldering session - I used a liquid rosin-based flux that I procured from Lajpat Rai Market. Wow! What a difference it made - I was able to do pretty consistent high solder joints most of the time.

Obligatory pics follow:

Much more packed PCB than my previous attempt

Cleaner solder joints thanks to the liquid flux

It fits in an Altoids tin!

I do have a couple of questions on which I'd appreciate some inputs on from the experienced members here:

1. The liquid flux was great but it leaves a sticky residue behind. I tried brushing it off with some alcohol and a tooth brush (and some tissue paper) but I've not been able to get it all off. Any suggestions on good techniques?
2. As I'll be putting this PCB in a metal tin, I'd like to insulate the leads at the bottom. I had an idea of using something like silicon glue but I dont want to spend any money on more tools! I tried using some black electrical tape but adhesion is quite poor and it keeps coming off. Any suggestions please?
3. Finally, while I like the concept of an Altoids tin amp, i'd really want to put it inside a nice metal enclosure. I've heard of people using enclosures from Hammond etc., any ideas on how it'd be possible to search for enclosures with given dimensions?

Ideally, I'd want an enclosure like below (not my pic):

Finally, I'll be getting my Super Simple Preamp from sachu888 tomorrow!! Cant wait to start on that, and I have the Starving Student Tube Headphone Amplifier as well for which I'm collecting parts. Going to be a fun few weeks! Thanks for reading guys

 

[manniraj]

Try aliexpress.com I think I saw some similar kind of cases out there.

 

[tcpip]

My soldering learnings

I find that clean soldering is largely a matter of how obsessively you clean the legs of the components and the PCB. I used to get dull joints a lot, till I realised that hard work pays off! :lol:

• I use some very fine-grade emery paper to rub down all component leads before I solder. I never skip this bit. After this, I need to wipe my hands clean to get the metal dust out and blow away the dust from the component surface.
• I use a clean dry towel and rub the PCB solder pads hard, to remove all traces of oil/ grime. Some solvent may be better.
• I keep a clean towel next to me when I work, and wipe my hands on it to remove sweat from fingers whenever I feel metal dust or sweat is collecting
• I try to touch the component leads carefully, so as not to get sweat or grime on them
• I use a soldering sponge, wet it with a thimbleful of water, and keep wiping the tip of the soldering iron on it as I work. Somehow, a good soldering sponge is not available at every corner store, and I have seen usable soldering-iron stands with lousy soldering sponges. So I use those stands but keep a separate small bowl with the sponge and water.

I am really sorry if all this is known to you, and I don't want to sound like I'm lecturing. But in my case, I actually did a lot of soldering, built a lot of stuff, before I realised that these things were not very obvious (to me!) but made a big difference. These became even more challenging when handling thick (4 sq-mm or more) wires during speaker building.

I never had the problem with solder quality which you refer to. Maybe I was just lucky.

I also believe that it's a very good idea to use alcohol to rub down and clean the post-soldered PCB, but I haven't started doing it. Maybe I should.

 

[tcpip]

Fred's Amplifiers is a great source of very good kits -- seems to be designed to give you good quality without the audiophile gold-plated hype. Am particularly curious about the crossfeed kits -- very few headphone amps today seem to have this option, and I feel it may make a big difference. Any opinions from anyone about crossfeed?

 

[tcpip]

Getting parts from the MNC resellers

Procuring from Lajpat Nagar and Lamington Road (the Bombay gulli for these things) is great as long as it works. But there are huge problems there too...

• For power transistors, you almost know they are fakes. For a lot of expensive chips, e.g. high quality opamps which have cheap look-alike alternatives, they are often fakes. I've seen even fake Bourns 3296 trimpots on L.Road. Electrolytic capacitors are often re-labelled. A lot of DIYers either do not know how common fake components are, or choose to live with the illusions.
• You will not get the better-quality parts which even sensible audio DIY builders may want, e.g. good film-and-foil capacitors or even MKP/ MKT caps which are preferred for speakers, signal pass-through caps, etc.. I am not even talking about boutique brands here, just simple Epcos/ Rifa, Solen etc.. Just try getting even an X-capacitor or X2-capacitor locally in ones and twos. :sad:
• You will never get slightly specialised things like 0.1% resistors (very useful for accurate active filters of any kind, including phono preamps) in small quantities. Ditto, non-inductive power resistors for emitter degeneration in power amps.
• I suspect you will find some of the more interesting chips very hard to get, e.g. LME498xx series, even the LM4702, the speaker-protection chips, etc.

I routinely buy 1% metal film resistors (the quarter-watt kind), ceramic and electrolytic caps, non-critical power resistors, common chips and transistors, etc locally. I get excellent E+I transformers made locally to order and excellent R-core transformers from Delta Transformer, again to order. Ordering such stuff from abroad would be super-expensive and probably not much use.

I find a lot of DIYers complaining for months on end while they try to get the rarer parts from various local sources, constantly posting about their difficulties, asking for suggestions -- but they will not order from RS, Digikey, and the like. I have found people refusing to spend Rs.600 to buy an LM3886 (admittedly a high price), even after months wasted looking for a cheap and reliable alternative source. I guess, for them, the thrill of part-hunting is part of the pleasure. I have never been able to enjoy that aspect.

I have often ordered from these big resellers when I haven't found the local parts looking right. I have realised what an expensive hobby DIY audio is in terms of time and effort, and saving money on slightly cheaper parts doesn't seem worth the effort. Totally a personal decision.

 

[suraj]

Fred's Amplifiers is a great source of very good kits -- seems to be designed to give you good quality without the audiophile gold-plated hype. Am particularly curious about the crossfeed kits -- very few headphone amps today seem to have this option, and I feel it may make a big difference. Any opinions from anyone about crossfeed?

I did make the modified linkwitz cross feed from Tangent's site,on a hand etched pcb.I made it only on a whim after i made my first cmoy(i had a lot of spare dale resistors).How good was it?I cannot say because I never used it for too long and dismantled it due to poor quality switches ruining the sound(it became scratchy).I like the effect though-it made the sound move if thats how one describes it.

I find a lot of DIYers complaining for months on end while they try to get the rarer parts from various local sources, constantly posting about their difficulties, asking for suggestions -- but they will not order from RS, Digikey, and the like. I have found people refusing to spend Rs.600 to buy an LM3886 (admittedly a high price), even after months wasted looking for a cheap and reliable alternative source. I guess, for them, the thrill of part-hunting is part of the pleasure. I have never been able to enjoy that aspect.

I have often ordered from these big resellers when I haven't found the local parts looking right. I have realised what an expensive hobby DIY audio is in terms of time and effort, and saving money on slightly cheaper parts doesn't seem worth the effort. Totally a personal decision.

I still whine about non availability of good parts locally
My issue with buying from retailers overseas is the 40$ shipping,more so,when i have ordered and realize i am missing one or two critical but very small parts.
Another problem is,minimum order quantity.But the real joy of "hunting" for parts locally is to find some unknown shop with a drawer full of exotic NOS parts!

 

[indialogue]

I am really sorry if all this is known to you, and I don't want to sound like I'm lecturing. But in my case, I actually did a lot of soldering, built a lot of stuff, before I realised that these things were not very obvious (to me!) but made a big difference.

Thank you so much for your advice and quite a bit of this is not known to me at all! This is just my 2nd-3rd soldering attempt and I have a lot to learn.

I do use alcohol to wipe down the board before and after soldering (with cotton ear buds) but some of your tips like wiping down the leads and not touching them, will definitely be kept in mind when I do my next kit. On solder, I wonder if using old solder makes a difference (does the flux core dry up for example) because the solder I have is around 4-5 years old now.

Procuring from Lajpat Nagar and Lamington Road (the Bombay gulli for these things) is great as long as it works. But there are huge problems there too...

• For power transistors, you almost know they are fakes. For a lot of expensive chips, e.g. high quality opamps which have cheap look-alike alternatives, they are often fakes. I've seen even fake Bourns 3296 trimpots on L.Road. Electrolytic capacitors are often re-labelled. A lot of DIYers either do not know how common fake components are, or choose to live with the illusions.
• You will not get the better-quality parts which even sensible audio DIY builders may want, e.g. good film-and-foil capacitors or even MKP/ MKT caps which are preferred for speakers, signal pass-through caps, etc.. I am not even talking about boutique brands here, just simple Epcos/ Rifa, Solen etc.. Just try getting even an X-capacitor or X2-capacitor locally in ones and twos. :sad:
• You will never get slightly specialised things like 0.1% resistors (very useful for accurate active filters of any kind, including phono preamps) in small quantities. Ditto, non-inductive power resistors for emitter degeneration in power amps.
• I suspect you will find some of the more interesting chips very hard to get, e.g. LME498xx series, even the LM4702, the speaker-protection chips, etc.

I routinely buy 1% metal film resistors (the quarter-watt kind), ceramic and electrolytic caps, non-critical power resistors, common chips and transistors, etc locally. I get excellent E+I transformers made locally to order and excellent R-core transformers from Delta Transformer, again to order. Ordering such stuff from abroad would be super-expensive and probably not much use.

I find a lot of DIYers complaining for months on end while they try to get the rarer parts from various local sources, constantly posting about their difficulties, asking for suggestions -- but they will not order from RS, Digikey, and the like. I have found people refusing to spend Rs.600 to buy an LM3886 (admittedly a high price), even after months wasted looking for a cheap and reliable alternative source. I guess, for them, the thrill of part-hunting is part of the pleasure. I have never been able to enjoy that aspect.

I have often ordered from these big resellers when I haven't found the local parts looking right. I have realised what an expensive hobby DIY audio is in terms of time and effort, and saving money on slightly cheaper parts doesn't seem worth the effort. Totally a personal decision.

I have to be honest, I would much prefer not to do the Lajpat Rai/Lamington Road market rounds at all and just order from the convenience of home, even if does come at a slight premium. But I think RS India only sells to companies (though I do have a Service Tax number if that helps) - are there any online stores that you would recommend, and Digikey/Mouser seem to ship their stuff from the UK and that gets expensive too

 

[jawedsoft]

Re: Getting parts from the MNC resellers

Hi TPCIP,
I have followed your posts on this forum. My experiences are much like yours.

I am looking for a transformer. I understand that you get yours from Delta. I too am planning to get mine from them.

I spent a long time at Lamington Road on Saturday..but there, my experience was same as yours...very few knowledgeable persons.
Where do you stay in Mumbai?

thanks,
Jawed
7738109225

 

[tcpip]

My issue with buying from retailers overseas is the 40$ shipping,more so,when i have ordered and realize i am missing one or two critical but very small parts.
Another problem is,minimum order quantity.But the real joy of "hunting" for parts locally is to find some unknown shop with a drawer full of exotic NOS parts!

Try farnell.in first, then try kitsnspares.com. They are two separate fronts for the same business, the former for B2B and the latter for B2C due to India's rules about FDI in retail, I guess. They are part of the element14 group, which is a very big retailer worldwide, I believe. If you find something on farnell.in, you will get exactly the same item at the same price from kitsnspares.com. If you can't see the item on the kitsnspares Website, you must email them and give them the Farnell part number, and ask for it. Tell them you cannot see it on kitsnspares.com. They will put it there on the kitsnspares.com site -- I have had responses in 48 hours. Then you can order from kitsnspares.com.

To order, you must go to the kitsnspares.com site, then click on the "Element14" tab, and then search for your requirements there.

These prices are higher than the local L.Road prices, but they bill you in Indian rupees and do not add any international shipping. Basically, if they cannot find anything in their local Indian warehouses, they will bulk-ship your items with the rest of their customers' orders from abroad to their Indian dispatch centres, and then dispatch your items from there to you. Therefore, this can take 2-3 weeks.

I have ordered some panel-mount RCA sockets from them -- a Neutrik brand item. Their prices were marginally higher than what I would have paid if I was living in the US and ordering from their US site. However, this is more expensive than what you pay for cheaper items sold on L.Road.

I have not ordered anything from digikey.in. Their .in site takes you to the product catalog of the US site, and all prices are in USD. But maybe they have made some arrangements for local shipping -- we need to try placing an order to confirm. If they are bothering to open a digikey.in site, I am sure they will be doing local shipping too, somehow.

 

[tcpip]

Re: Getting parts from the MNC resellers

Where do you stay in Mumbai?

In Navi Mumbai.

 

[tcpip]

I still whine about non availability of good parts locally

By all means, sir. It's seriously fun, isn't it, with a bit of bitching and cribbing amidst a bunch of good friends?

My issue with buying from retailers overseas is the 40$ shipping,more so,when i have ordered and realize i am missing one or two critical but very small parts.

Yes, if you've missed a part or two, then it's really infuriating, but otherwise, Digikey seems to be shipping to India at a flat rate of $40. This may not be cheap if you are ordering $20 of parts, but if you are ordering large amounts of stuff, then Rs.3000 seems an affordable mark-up to pay. (On top of that will be Customs Duty, of course...:sad: )

Unrelated: I just bought Rs.4500 worth of capacitors from L.Road a couple of days back. These are 64 Elna capacitors, 4,700uF, 105 deg-C, 25mm dia, 40mm height. Original Japanese import. The cheapest online alternative I was seeing was some Cornell-Dubilier caps, 4,700uF, 85 deg-C, snap-in types, from farnell.in, at Rs.140 each. I think I got myself a good deal.