rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Nov 30, 2006 2:32:42 GMT
Thems fightin' words bub ! and if the years had not taken such a toll on me I'd consider swimming over there ASAP and gettin' some friggin' respect !!!! would that be the same "rapid delivery" service that it took two months to get a package to my door ? TOOT,TOOT.........
|
|
|
Post by PinkFloyd on Dec 6, 2006 13:21:45 GMT
What's happening your end xerxes??? keep us updated man.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Dec 6, 2006 14:53:49 GMT
|
|
|
Post by PinkFloyd on Dec 6, 2006 14:59:32 GMT
?? No mention of a Corda HA-1 Mkll there Rick, just a WNA MKll and a Pimeta.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Dec 7, 2006 0:43:39 GMT
You are absolutely correct Mike but in my defense I was A-overslept so was not entirely awake yet and had not had my first cup of java B-was heading out the door totally disorganised and in a semi "panic" knowing i would forget something because of the highly out of character late wakeup and the "trying to make up time" state of chaos i was in. In my experience rushing ANYTHING will normally not only make the thing you are trying to do NOT happen faster (unless the happen faster is trying to dump your date 'cause rush that act and she will be gones so fast the only evidence she was ever there will be the faint smell of "female" ) but in fact will take longer when in the rush you make mistakes that need to be corrected so taking more time.
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Dec 7, 2006 1:06:12 GMT
At the moment the Corda HA-1 MkII is a rather expensive paperweight with an LED that illuminates if you power it up. I've scrutinised the solder joints, scrubbed the PCB with a toothprush and flux clean, held it up to the light, probed it with a volt meter. I can confirm that current gets all the way from one end of the circuit to the other, but it doesn't actually, er, amplify. Short of going to college and studying electronics, which I don't really have time for, I don't know what else to do.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Dec 9, 2006 23:57:37 GMT
damn shame Owen but don't give up man ! There is not a doubt in my mind it is some silly little thing easily overlooked and not a total washout going on here with my money on something jack related (melted internals from the excess heating required to get heavy metal to flow solder and why I use a BEHEMOTH solder gun for all things mechanical soldering related )
|
|
|
Post by PinkFloyd on Jan 14, 2007 23:27:59 GMT
Had a good old probe under the bonnet Xerxes and the reason your amp is giving 11.5V at the output is because you've fitted 1500ohm resistors between the non inverting inputs and the negative voltage rail. These should have been 15M types (15 "megohm") ...... only a few million ohms "out" but enough to cause such massive offset. You've also fitted 22ohm instead of 0.22ohm in the PSU which would explain the 27.7V between the outer pins of the buffers instead of the typical 30V. Both of these are easy mistakes to make, maybe mistaken colour codes for the resistors etc..... I'll send her back over to you and you can fit the 15megohm and 0.22ohm resistors, it would be a shame if I finished your absolutely superb job off, you know what the problem is now so only proper you see the build through to completion. I've got to say Xerxes, and I'm being absolutely serious here, your soldering is the best I have seen from any DIYer.... it's 100% spot on, in fact it's the best soldering I've seen for quite some time be it DIY or commercial..... excellent workmanship. Your panel work is also top notch, that's one seriously professional looking amp throughout If you ever decide to try FET opamps in the HA-1 MKll then be sure to remove the 15Megohm resistors (don't jumper over the pads, just remove them) otherwise you'll suffer equally mind blowing levels of offset. The pads here are extremely fragile so you may want to fit sockets here if future opamp rolling is envisaged.... ie: if you want to try a FET opamp you just unplug the 15megohm resistors. All the best. Mike.
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Jan 17, 2007 14:50:16 GMT
Hi Mike, The amp arrived back safe and sound and hour or so ago. It's Alive!What's a few million ohms between friends. ;D Apparently, enough to turn a working amp into one that doesn't. Why I decided that 15M = 1.5K will have to remain one of life's little mysteries. Tell me about it, one of the little buggers decided to go for a burton when I removed one of the 1.5K resistors. I managed to get round that though. Having got it all back together and working, I think I'll leave it alone. Thank you very, very much for the parts and having a look at it for me and to Rick for the board as well.
|
|
Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
|
Post by Sol on Jan 17, 2007 14:59:46 GMT
Thank you very, very much for the parts and having a look at it for me and to Rick for the board as well. Photos? Inside and Out?
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Jan 17, 2007 15:42:17 GMT
You can see the amp here.
|
|
Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
|
Post by Sol on Jan 17, 2007 15:54:37 GMT
You can see the amp here. Nice looking those hammond cases - and your work inside the case looks betetr than my hamfisted attempt at electronic assembly! So .. the real question on my mind is, of course, what does it sound like?
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Jan 17, 2007 16:26:02 GMT
Shhh! Don't let Rick here you say that. Pretty good. I have only my recollection to go on, but I'd say similar to the unmodified WNA MkII, which is hardly surprising as it uses the same LM6171 op-amps. It's very smooth, but like the un-modded WNA, slightly lacking in "bite" and low end punch. My now modified WNA, currently using three OPA627 comfortably betters it with a bit more of everything. I have also got some AD843s on order to try in the WNA - when they eventually turn up. To be honest I wasn't expecting the Corda to better the WNA, Mike's had both amps and given the amount he wrote about the WNA, I'm sure we would have heard about it if the Corda was a better sounding amp. ;D This was my first "from the PCB up" build and it was really a case of seeing whether I could do it. It seems I can, albeit with the end result having to make a round trip to Scotland for a once over from someone that actually knows what they're doing before we get it up and running.
|
|
|
Post by PinkFloyd on Jan 17, 2007 17:56:10 GMT
Glad you got her going at last Xerxes The 15M thing was an oversight and an easy enough mistake to make.... don't beat yourself up over it, the rest of the build is 101% professionally executed.... flawless. I agree, it's a pretty lightweight sound but a "nice" sound. certainly not fatiguing or shrill just nice and light / airy. Of course it'll fill out a bit more as it burns in, they all do. All the best. Mike.
|
|
xerxes
Been here a while!
Posts: 1,115
|
Post by xerxes on Jan 17, 2007 18:22:22 GMT
Absolutely, it's not an unpleasant sound in any way shape or form. Just not as good as the modded WNA; the WNA mods have given it a considerable boost, prior to the mods, I don't think there would be much in it at all.
|
|