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Post by PinkFloyd on Jan 1, 2009 14:29:43 GMT
Come on guys, you've built the amp now it's time to show us the finished article! I'm away from home at the moment but as soon as I return I'll take pictures of mine and include them here (great excuse to test out the new camera!) so come on...... let's see the pRon
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Post by Deleted on Jan 2, 2009 1:32:00 GMT
The M1 Am 1 - Early testing phase. (Not completed)
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Post by Deleted on Jan 2, 2009 5:46:13 GMT
When I give it a good workout and possible tweaking, then change it to U.S.A. mains voltage, I could send a couple of those recovered 4.7uF polyprops with it for you to fit ! (I have a spare couple after fitting the 4.7uF Auricaps in my power amplifier.) BTW, you may have noticed the very recent post by another Sydney member about fitting those caps ? Alex P.S. The JLH has a small mod for you to evaluate,(you will see tiny added 2.7K resistors hard up against the top and bottom 2.2uF red Wima capacitors) and yours has green LEDs just to be different !
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Will
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Post by Will on Jan 2, 2009 10:01:27 GMT
OK, the SCHA built by Mr Woodvine (me). Please forgive the festive tablecloth! The only mod left to do is swap out the 470uF on the main amp board ps rail, over to 100uF. The wires to the headphone socket are not as tight as they seem, either. Case is from HiFi2000. Really need to find something to fill all that space in..
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Post by Deleted on Jan 2, 2009 10:23:26 GMT
Wilbur A nice clean layout,and looks good . Having room to move in a nice case like that makes all the difference! You could always fit a selector switch for at least one more input, and a pair of extra RCA sockets to go with it. If you have a Power Amplifier, you could also consider another pair of output sockets as per the recent post in the SC HA Tweaks thread. Alex
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robertkd
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Post by robertkd on Jan 2, 2009 12:33:36 GMT
Wilbur, your case it a Galaxy 230*200*60?? incidentally well done, alas I need to get a case for mine until then it sits on the desk
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Will
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Post by Will on Jan 2, 2009 13:52:23 GMT
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Post by traf on Jan 2, 2009 18:45:18 GMT
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Post by Deleted on Jan 2, 2009 20:03:57 GMT
What,no front panel LED ? Spectacular build, though !
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Will
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Post by Will on Jan 2, 2009 23:33:41 GMT
What,no front panel LED ? Spectacular build, though ! Your right, it is spectacular, probably the best conventional build posted in the Jaycar threads, IMO. As for unconventional, I think cjarchez would be the one for my vote. As for anybody else, I suppose you could consider the gauntlet firmly thrown! Come on, get posting!
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Post by PinkFloyd on Jan 3, 2009 11:30:12 GMT
Traf, a very nice job indeed! I will eventually rehouse mine in something more streamlined but ONLY when I've finished faffing about with it. The cheap Maplins enclosure may be pug ugly but it facilitates FAST removal of each individual board when it comes to swapping out capacitors etc. I'll get some pictures of my road accident uploaded as soon as I return home.... it aint pretty but she sounds nice ;D
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Post by PinkFloyd on Jan 3, 2009 11:32:57 GMT
By the way guys.... what's all this headphone socket at the back of the amp lark all about, am I missing something here? I always go front mounted.... rear entry has never really appealed to me ;D
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Post by Deleted on Jan 3, 2009 12:17:36 GMT
By the way guys.... what's all this headphone socket at the back of the amp lark all about, am I missing something here? I always go front mounted.... rear entry has never really appealed to me ;D Other than suiting the layout of the PCB, it helps amplifier stability by keeping input and output wiring well separated. That is even more important with wide bandwidth designs with later I.C.s, particularly with the way some people take liberties with cabling of the unshielded type. Besides, not everybody collects headphones like Imelda Marcos collected shoes , so that means that the headphone lead can be kept out of the way of size 9s. (hopefully!) Geez, next you will want to give it juice into a front panel I.E.C. FEMALE socket ! Anyway, because of several requests from the Miami headphone collector extrordinaire, you will notice that the photo of the almost finished replacement actually has a front panel headphone socket. Anyway, why do most affordable headphone sockets have to look butt ugly?
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Post by PinkFloyd on Jan 3, 2009 12:43:40 GMT
Pedantic man, pedantic..... No reason at all why the headphone socket should be strapped on the rear other than you Australians do everything upside down,,,, hell, even the water in your toilets flushes the wrong way round ;D
Front mount the head socket and position all the power gubbins over to the right of the amp board.... twisted pairs mate, perfectly good for keeping shit out...... I see ZERO practical advantage having the head out positioned at the back....... some people have their amps in racks and what a pain in the arse it is having to fumble about the backside looking for the hole to insert your plug in.....
ALSO...... and it's a BIG also...... cable strain..... with a rear mounted head out you are effectively doubling the cable (going into the jack) over and, with time, this will weaken resulting in broken internal wires.... PLUS if you DO trip over the cord you'll end up with a ripped cord AND an amplifier on the floor with this rear mount implementation..... if it's front mounted and you trip over the cord the jack will (9 times out of ten) come out of the headout.....
So, you can see there is a very good reason why nine out of ten head outs are front mounted and it's not for "looks".
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Post by Deleted on Jan 3, 2009 13:24:00 GMT
quote] twisted pairs mate, perfectly good for keeping shit out...... [/quote] Tell that to Graham Slee ! If you are going to extend leads from the rear to the front of an amplifier,(or the other way around) they should be well screened.Twisted leads are O.K. for short distances, but only when not in close proximity to an input circuit, if the lead is on an input or volume control, or vice versa if the lead is an output lead . Bite your bum, or I will ask Richard Dunn to give you a lecture about magnetic fields and Waveguides ! I seem to remember someone even going to the trouble to shield polyprop caps, and earth denuded electro cases ?
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Post by PinkFloyd on Jan 3, 2009 15:49:55 GMT
Yeh, I'll fit some shielded stuff when I get home.... I'm pretty much satisfied with the sound now and doubt I'll be doing any more tweaking so will lose the cheap hook up string and employ something a bit more suitable.
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Post by PinkFloyd on Jan 3, 2009 15:52:02 GMT
Next someone will suggest a wooden case! The ultimate enclosure would be a coffin.... that way, when you die, you can be buried inside your amp..... cool or what? Oooops !
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Post by Deleted on Jan 3, 2009 20:22:00 GMT
Yeh, I'll fit some shielded stuff when I get home.... I'm pretty much satisfied with the sound now and doubt I'll be doing any more tweaking so will lose the cheap hook up string and employ something a bit more suitable. Mike If you zoom in on the photo I posted of the M1Am 1, you will notice a couple of ferrite beads on the input links.I am not sure what happened to cause Miguel's HA burnup when fitting those big polyprops, but in case there is a source of bad EMI locally, that may have contributed to oscillation, and Miguel didn't cause it, I decided to further minimise the risk. I believe you recommended similar with the WNA due to it's wide bandwidth ? Alex P.S. I would have fitted ferrite beads to the 100 ohm output resistors of the I.C. , but it was too hard to implement.
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Post by Deleted on Jan 3, 2009 23:59:57 GMT
Miguel As it is unique to yours,and most likely not necessary anyway, I will email you a modified photo. Alex
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Post by jeffc on Jan 5, 2009 8:57:30 GMT
"Next someone will suggest a wooden case!" Miguel, Now that would be a novel idea!!! I used a wooden box because I had it, as the boards fitted nicely and of course as we all know wood sounds way better than plastic, steel or aluminum. Looks OK too. Here's my SCHA in an appropriate setting. cheers.. jeffc
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Post by Deleted on Jan 5, 2009 9:47:24 GMT
jeff Interesting construction. However, even after enlarging the photo,I am unsure as to how the mains side of things is actually wired. I presume that it is a ferrite suppressor core that some of the wiring is going through ? Are you able to supply more detail of your mains wiring, perhaps in a rough drawing ? The on/off toggle switch also has what appears to be an exposed solder lug that could have benefitted from a small piece of heatshrink tubing, or similar. Your wiring may be perfectly safe, and meet safety standards, but I feel sure that Mike would agree with me, that the moderators and admin, MUST encourage safe mains wiring practices, for the protection of members and their families, so please do not be annoyed at me for asking for additional information. Alex
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insomniac
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Post by insomniac on Jan 5, 2009 22:51:32 GMT
"Next someone will suggest a wooden case!" Miguel, Now that would be a novel idea!!! I used a wooden box because I had it, as the boards fitted nicely and of course as we all know wood sounds way better than plastic, steel or aluminum. Looks OK too. Here's my SCHA in an appropriate setting. cheers.. jeffc Better not leave that on damp ground for too long... it might sprout roots Seriously though....nice amp...I like it!
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Post by jeffc on Jan 5, 2009 23:37:01 GMT
Hi Alex, Yes there does need to be a couple of changes made under the hood for safety. That said, its safe enough with the lid on, I think. Wiring. Power cord through hole, large cable tie fixed tightly so it can't pull out. Active wire in and out of a fuse holder under the dark rectangular piece of stiff cardboard bluetacked above. job #1 replace with a covered 'in line' fuse holder or similar. Active and neutral continue to the pins of the X2 mains cap in the corner next to the switch. Cap bluetacked in very firmly on 2 sides so I'm happy with the safety of this, pins are inaccessible. Active in and out of the front switch. job #2 to shrink-warp this and the bare solder joint linking the power cord and transformer neutrals. The rest is OK I think. Transformer secondaries run through a ferrite clamp scavenged from a computer monitor video cable. Mains earth wire hooked straight in to the 0V in point of the PSU board. Additional heat sinks with some fins trimmed to miss caps added to help dissipate heat from the regulators, which can get quite hot in this box. job #3 is to drill a few ventilation holes. OK, confessional over, resolutions made and sins hopefully forgiven once the jobs are fixed. Anything else you can see to use me as an good example of what not to do if one wishes to play with things 240V safely. ;D cheers..Jeff Insomniac, Left there of a day or two it sure would get lost beneath that elephant grass I've just gotten laid that needs mowing twice a week over summer, pain in the it is. Re the amp build, cheers, space left between the attenuator and HA board to fit big HQ PP caps like copper-clad Obbligatos should I get the urge one day. Miguel, Good spot. Ages ago I bought 30 ft of 0.5 mm dia audio-grade silver wire for cheap so I thought this would be good place to use some of it up. Being the I am I also used it for links on the HA board, again just because I have it sitting in the draw waiting to find use.
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Post by Deleted on Jan 6, 2009 0:01:52 GMT
jeff You have covered the main point of interest, the obligatory .5A fast blow fuse in the primary that most Toroidal transformer manufacturers request. The main reasons that I fitted a piece of aluminium under the toroidal were to earth the transformer in case of an insulation breakdown. (for whatever reason) This would cause a mains fuse/circuit breaker to operate. One of the other reasons was to spread the heat of the transformer a little, particularly as most cases would be plastic, or the occasional wooden case like yours. The remaining reason was to provide a convenient earth point for the shaft of the volume control/attenuator, to keep hum out, as well as prevent hand effects when adjusting the volume. Alex P.S. I didn't want to be seen as too picky, so I didn't mention those leads that Miguel referred to. A better option, but trickier to implement, is to use short lengths of low capacitance screened cable. I find S-VHS cable from either an old lead, or bought by the metre from places like Jaycar is ideal. You do need practice though, to avoid cutting off too many of the screens wires, or cutting through the centre coductor, when you only want to remove a short section of insulation for terminating it ! When you use your method,(see photo) you are increasing the chances of EMI ingress, as well as reducing the HF separation between channels. This reduced separation would be a shame, particularly when an attenuator is used, which not only improves bandwidth, but possibly aids channel separation in the better attenuators, which are a bonus on top of the higher resolution available. Alex.
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Post by PinkFloyd on Jan 6, 2009 0:10:06 GMT
Yes, I agree Alex... safety is paramount and should be encouraged at all times, hell.... we don't want our members spontaneously combusting or electrocuting themselves or others DIY is just that though and when people "do it themselves" there is very little you can do other than advise them on the best practices to adopt..... if they decide to probe the IEC inlet with their tongues to check voltage then, so be it.... there's nothing we can do.
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