It was first published in Silicon Chip magazine (Aust. ) in November 2005. Alex
Good to see someone actually mention the people who deserve the real credit. The guys at Siliconchip design and test the circuit, create a nice PCB and then write the article and instruction sheet that's easy to follow.
Jaycar just stick the bits in the bag and post it to you.
BTW: I find Weetbix taste better using a soup spoon rather than a desert spoon. The difference is not as much as the difference between Weetbix and VitaBrits. One of my friends doesn't agree with me but she likes VitaBrits so she must have a cloth tongue. Strange but true.
Couldn't agree more Leo! Bloomin' horrid things that suck the soul out of the sonics.... much better strapping a good old class X2 cap across the IEC L/N tags.
You don't happen to have any LM4562 kicking about do you Leo? I went hunting for mine today and couldn't locate them for the life of me I'll be happy to do a swap with you if you do have any at Leo HQ.
Sorry I'm late getting back mate, been busy, not had time to fart
I only had one of the LM4562 DILs BUT I do have one SMD LM4562 in my stash, would that be ok for you? it obviously needs to be mounted on a browndog if you have one
That would be great Leo.... I do have a spare B-Dog
BTW guys the circuit for this amp looks SOOOO similar to a commercial unit out there which is FAR from cheap ;D
Any hints? NAIM or Sugden?
L*****n ;D Just had a look at the schematic, its not exactly the same but is easily converted, well be no problem for the experienced bodger The feedback is different and a bit of the output section, all it takes is a bit of altering
I'd actually put a small bet on it this cheapo will beat it once its been modified
I've ordered up a PCB etching kit & it looks like I should be able to make up 3 or 4 JLH boards (the mini type) as easily as making up 1, so if anyone wants to try it when they get their kits let me know.
I won't be waiting for the amp kit so with a bit (lot?) of luck I should have a few done pretty soon.
I picked up the headphone amp and PSU kit from Jaycar over the weekend. It cost about 21GBP ( I won't know exactly until the bill arrives ) as I managed to get at trade rates so it wasn't much more than ordering from the UK and at least I now have one.
There was another amp and PSU on the shelf so if anyone in the UK wants me to get it for them I will try but I can't say if I will be able to get trade rate again, it will then need postage on top once I get back home. PM me if interested.
Alex, would I be better off getting a toroidal from Jaycar or asking Mike for a traffo? Also the kit says that a pot is needed any ideas? Do jaycar to a good one?
Rossman If you can get a 15-0-15 20 VA toroidal from Jaycar, and are not worried about the little extra weight in your luggage, why not ? Just one thing less to worry about later on, and they aren't too expensive here.(30VA would be a little better, but only Altronics stocks them over the counter) You could use ordinary 50K dual logarithmic pots initially, then upgrade to something like Alps Blue Velvet later on. Mike may be able to supply one of those ? Did you get the kits at Hornsby ? If so, you better grab the other HA kit before I do !( just kidding, I have another to modify in the full SC Studio Preamp! ) Alex
mistergreen and Miguel Due to the short lengths involved,any kind of shielded audio cable is fine. I often buy a 1 metre length of S-VHS cable, and strip the sheathing to obtain the thin shielded red and white cables inside it. For power supply wiring I usually use the 3 conductors from inside a short length of 7.5A or 10A mains cable. Use the yellow-green (or green) for earth wiring. I normally use the blue for -VE DC , and brown for +ve DC. SandyK
kittenyberk A chance is if you are able to contact Rossman by PM,( or other means). He did say that for anyone wanting one, that he could bring one back, plus postage at your end. I understand that Jaycar at Hornsby still had one left on the shelf after his visit. He hasn't been on line since earlier yesterday. SandyK
I had a quick prod about under the bonnet today, was pretty zonked so didn't do a lot, basically whipped the inductors out of circuit, replaced the 47R with a 33R (33R sounded better to my ears), removed the 10uf input caps (slight improvement again) and then fitted the LM4562 (cheers Leo).
LM4562 was quite nice in circuit but not the bassiest of chips is it? Not offensive, quite nice presentation but ever so slightly wishy washy sounding in places.... "airy" yes but satisfying overall? No. Not so far anyways, I'll try it again once performing all of the AK mods and fitting the JLH.
Fired my original AD-843's (on B-Dogs) back in and "aha", the bass had returned.... a lot warmer sounding than the LM4562 however.
Then rolled in an AD8066 which I currently prefer to both the 4562 and 843 being not only generous in the bass department but also extremely detailed, spacious and musically involving.... I'll let this puppy burn in for 24 hours and see how she sounds then but so far, excellent.
I haven't bothered with any component changes (apart from 4 x 100uF fine gold) and will be doing one thing at a time and evaluating the changes..... deffo better with the input caps removed, the inductors removed etc. and I expect it to get better and better the more it's tweaked.
Great little amp to work on too, those pads will withstand a fair bit of abuse I'd imagine
Mike AD8066 is one of my favourite chips too. BUT keep it running at + and - 15V, and BURN might be the result. Leo and myself recently had a discussion with the Singapore Stallion about this. Even if it survives, it will deteriorate. 24V in this case, is + and -12V. Analog Devices data sheets are worded differently to the others. (5V =+ -2.5V)
Re the LM4562 being bass shy : Trust me, this won't be a criticism when the JLH is fitted ! Alex
AD8065/AD8066 FEATURES FET input amplifier 1 pA input bias current Low cost High speed: 145 MHz, −3 dB bandwidth (G = +1) 180 V/ƒÊs slew rate (G = +2) Low noise 7 nV/ãHz (f = 10 kHz) 0.6 fA/ãHz (f = 10 kHz) Wide supply voltage range: 5 V to 24 V Single-supply and rail-to-rail output Low offset voltage 1.5 mV max High common-mode rejection ratio: −100 dB Excellent distortion specifications SFDR −88 dB @ 1 MHz Low power: 6.4 mA/amplifier typical supply current No phase reversal Small packaging: SOIC-8, SOT-23-5, and MSOP APPLICATIONS Instrumentation Photodiode preamps Filters A/D drivers Level shifting Buffering
Miguel No thoughts on those . The general consensus at the moment is that the LM4562 (or the LME named one) is the chip to beat if properly implemented. Naturally, I have fitted a quality DIL socket ready for the next greatest since sliced bread. Don't take too much notice of the rersults with different chips before a JLH is fitted. Leo and Allan will vouch for the fact that things are very different when using a JLH. Alex P.S. EMAIL sent.
Jaycar Headphone Amp Kit availability problems. In Silicon Chip magazine's May issue, Altronics has the Headphone Amplifier kit at the reduced price of AU$25. I understand that they do export as far afield as the USA. Their catalogue no. is K5503. Enter the kit no. into "Search" Their catalogue no. is K5501 for the Power Supply (AU$15.95)