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Post by PinkFloyd on Dec 16, 2006 0:03:45 GMT
This is where the heat comes from folks! Not so much the transistors but from the 5W 100ohm resistors, put your finger on one and you'll see what I mean! HOT eh? I added a bit of supplementary heatsinking round this are and actually bonded a sink onto the sides of both the 100ohm resistors with stuff similar to JB weld, so powerful is this gear you'll never get it off, the resistors now run warm to the touch so job well done.... the grey epoxy steel looks a bit mickey mouse but believe me it does the job very well. Next on the hit list was fitting a dip8 socket to enable opamp rolling. I went for a good quality gold plated, turned pin type. The surrounding area is "tight" (to say the least) so you've got to make a bit of space so you'll be able to roll in opamps easily. Move the 100nF cap under the board (the yellow one) and carefully bend the LED legs flush with the front panel.... ensures there's enough room to fit / remove opamps. 2 x 16V 4700uF general purpose Jamicon capacitors are fitted as stock (and in my example were fitted the wrong way round!!) I absolutely detest these capacitors so removed them pronto! There is also provision for snap in capacitors to be fitted so that's just what I went for........ First in were a pair of el cheapo Suntan 105C 35V 10,000uF. I also swapped out the 2 x 100uF stock Jamicons for a couple of 35V 100uF ELNA Cerafines. HUGE improvement to the sound, the extra capacitance pays off BIG time, and then some. Suntan 10,000uF and 100uF Cerafines in position. Satisfied that the 10,000uF made a major improvement I removed the Suntans and fired in a couple of 105C 10,000uF 105C dubiliers... no difference to the sound but a cap I like to use when I can. Also Replaced the stock 1N4002 diodes with UF4007 (1000V) ultrafast types.... again, subtle but noticeable improvements to the overall timing and clarity. Model number written on the side of the cap. I've also replaced all the 63V film caps with 400V film caps (polyester) all bypassed with small polyprops (EVOX) (ie: 100nF polyester bypassed with a 10nF polyprop, 470nF nF polyester bypassed with a 47nF polyprop) Most of this is under the board and under board mounted film caps are all supplemented with a blob of hot melt glue (before soldering into position) to ensure strain relief, mechanical integrity. Another thing I did was replace the "thread" like hook up wire to the head socket with some good quality thick copper gear.... doesn't necessarily sound any better but a bit more of a reassuring look to it as far as integrity is concerned. From what I can see there's really not a lot else can be done to improve this amp further..... the designer has put all the right holes in the right places but, in parts, populated those holes with cost effective parts..... Alpar (from HEED) has already mentioned that if budget were no object these holes would be populated with more expensive (mostly more capacitance) parts and he agrees "of course it will sound better there's no doubt about that" To put the amp to market at $350US or £250GBP compromises have to be made somewhere. Fortunately it won't cost the earth to populate the holes with parts the designer would have liked to have used if cost were no object. About £4 for the two 10,000uF caps, a few pence for the Ultrafast diodes, a quid for the heatsinks, pennies for the opamp socket (dip8)........ very cheap but VERY effective mods. The stock opamp is the NE5532 (an opamp I love) some people will call you the antichrist if you even dare suggest they sound good, I think they are lovely sounding devices ;D (and considering they're universally used in most recording studios.........) Do they sound best in the HEED though? A question I'm in the process of answering....... To date I have rolled in AD-843, OPA2227 and OPA2107. The three of them each displaying their own unique / signatures / characteristics. AD-843 - Grainy, raw, open, organic, A realistic wellies and bucket listen, all four seasons in just one day... warm, cold, wet and dry, imagine apples falling off the tree then fast forward to basking in glorious sunshine on a beach.... to my ears 8.5/10 OPA 2107 - Velvety, smooth, easy listening, laid back like an overripe grape basking in the sun, no hurry, don't rush the brush type of presentation..... nice if you like that style..... to my ears 8.5 /10 OPA2227 - best of the bunch in the bass department (to my ears) toe curling depth / extension. Fruity in places yet decidedly mellow in others..... fun 8.5/ 10 NE5532 - Warm, rich, sprinkled with sugar and cinnamon... a doughnut like, easily digestible, fast food, satisfying signature that will appeal to a broad palette time and time again 8.5 / 10 Next up under the hood are OPA627BP (on Bdogs), AD8620 , LM6172 and OPA2111KP. Stay tuned.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 16, 2006 1:03:54 GMT
Hey Mikster,have you attempted any "resistor rolling" in the power resistor position ? I have found that in a similiar circuit,the Szekeres type Single Ended Class-A Follower the source resistor (Emitter resistor in the above being a bipolar transistor) selection made DRAMATIC changes in the microdynamics area,better even than a full blown CCS with the absolute worst being one of those sand cast resistors shown in the above pics followed closely by one of those fancy "built in heat sink" types.
think non-inductive here man
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 16, 2006 15:31:39 GMT
Not sure what you can source in the UK Mike but the Mills and Reidons are good here.Not really expensive when you consider what some parts cost www.thlaudio.com/MillsohmE.htmwww.welbornelabs.com/mills.htmwww.soniccraft.com/mills_resistors.htmIf you need something dead nuetral to slightly brighter side of nuetral that bolts up to a heatsink there are the Caddocks in the power tab package but they are VERY expensive,to me personally no bargain. Another point,try a carbon comp if there are any non critical signal path resistors such as input networks,any resistors between the op amp and the driver stage but NOT feedback loop.Do the DMM Left/Right resistor match thing and go to ballpark values and the bad press on carbons from lab rats (as opposed to music lovers) can be ignored.Stay with prescion parts in prescision circuits but do try and stay away from hard sounding MF resistors,beyshlkags (yeah i know it is mis spelled ) are workable have fun dude
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xerxes
Been here a while!
Posts: 1,115
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Post by xerxes on Dec 16, 2006 19:43:52 GMT
Hi Mike, I ordered the voltage regulator from Welbourne labs today, as a chrimble pressy, I got you some 100 ohm resistors, 2 Mills and 2 Reidons, so don't get any of those.
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Post by PinkFloyd on Dec 16, 2006 21:14:47 GMT
Oh xerxes, that's really kind of you mate I'll have great fun trying those out and, Rick, thanks for the inspiration if they sound good you'll have me firing these into all my amps My present to you xerxes, get that HA1 MKll over to me after the Christmas postal madness has subsided
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Post by PinkFloyd on Dec 16, 2006 23:24:14 GMT
Hey Mikster,have you attempted any "resistor rolling" in the power resistor position ? I have found that in a similiar circuit,the Szekeres type Single Ended Class-A Follower the source resistor (Emitter resistor in the above being a bipolar transistor) selection made DRAMATIC changes in the microdynamics area,better even than a full blown CCS with the absolute worst being one of those sand cast resistors shown in the above pics followed closely by one of those fancy "built in heat sink" types. think non-inductive here man You've got me chomping at the bit now Rick, resistors are one area I've never really bothered with when it comes to SQ, as long as they measured close (per channel) that was good enough for me. David White used to waffle on about the benefits of low temp coeff resistors, others waffle on about Welwyn RC55Y.... I never, honestly heard any difference over carbons or standard 1% metal films in cool running amps. However! The resistor in question in the HEED runs as hot as a burger griddle so now we're talking about a resistor that could really benefit from being low temperature coefficient and non inductive (as you have pointed out) what about these from www.rapidonline.com part number 62-0018 ? I'm open to all suggestions in this area and will be trying the wirewound types you linked to in your post when they arrive. For the time being I've been going into depth with the opamps (reminds me of the rolling fever I had with the WNA amps!) to my ears, so far, the AD-823 is the one for me, with it onboard my test tracks (tracks I listen to for about 4 hours a day 365 days a year... seriously ) sound spot on, just the way I expect them to sound. Yello "the eye" track 5.... the bass drops (3 seconds in) go down a couple of octaves deeper than the rest of the chips I've tried..... pom pe pom pom, pe pom pe pom pom (bass drop) wammmmmmm...... more extended, no roll off... goes right down without being wooly or rounded.... nice and tight. Yello "the eye" track 14. Plenty of engineered midrange noise artefacts on this track, AD823 brings them out superbly (the other chips didn't come close) There's also a snap and immediacy to the midrange with the 823 that's missing with the other three, they sounded a tad more congealed with nothing really shining through. I like the occasional kick in the head when listening to music and the AD-823 obliges.... I expect a drum whack to "whack" and the rasp of a trumpet to sound like the rasp of a trumpet (not like a bee farting) AD-823 delivers. A few more to try (quite a lot more to try actually ;D) but, so far, AD-823 is my favourite out of the OPA2227, NE5532, OPA2107 bunch.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 17, 2006 0:03:52 GMT
Likely the reason you never had noticed any benefit "rolling" resistors is your experience mostly runs to Op Amp based circuits and "all one flavor" resistor per wattage so for instance every 1/2 watt resistor would be Brand-X I deal mostly with discrete stages or valves so the surrounding parts per stage (single transistor/mosfet/triode) take on a more important role thus ARE audible in the choosing with some more than others depending on location in the circuit. The source (mosfet) or emitter (transistor) current setting part in a class-A stage is one of the more audible areas and why you see so many passive and active variations.i have pretty much gone through them all and while each has merit I personally find a good non inductive resistive load sounds the most natural,more relaxed and pleasing letting music flow through rather than the effect of an active stage here that to me sounds more accurate and with tighter bass at first but that over time takes on an "electronic" sound,a sound where the amp dominates the music and not the other way as it should be. Actually I have pretty much sworn off metal film resistors as a class of parts unless I need that extra margin of stability considering even the good ones to have too much of an "electronics" sound. The flip side of that is use all one type,all one brand and you choke the amp into producing a "one note" sonic profile where everything that flows through takes on the same exact "tone" and that means again amp domination over music instead of the amp being just a means to get from A to B with proper drive levels. Cap rolling is usually the dominant mod most partake because caps are GROSS correction devices.Resistors can be considered more of a FINE correction device,one that you hear more in the details than in the overall tone but that once you get right you get that "Oooooh yeah ! THAT's what I'm looking for" smile listeing to music.It is the resistor that will take your sonics to hard and cold or blood and guts,from sterile to lively,from "etched" to "round" . If you can get the R/C combos to work harmoniously as in clean caps with no grit or glare,that edginess and smearing of details caps are known for you can then dial in the overall "tone" by using resistor choice and don't beleive the crap about "a resistor is a resistor is a resistor and if it adds to the sound it is a bad one" because they ALL add to the sonic imprint so the trick is to try and get balance instead of saying "this is the BEST". Another point.Large wattage resistors (like large votage caps) SOUND better so a 1 watt sounds better than a 1/2 watt so if you have the space always move up when possible.that and choose non-inductive which usually means WW or carbon comps www.tubedepot.com/r-30bj500.htmlwww.tubedepot.com/r-cc-1-nos.htmlthe above are nice directly in the signal path (coupling) with non inductive WW usually the best choice in any circuit location that draws current.If the rest of the circuit is capable of reproducing a clean signal these puppies will flesh it out
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 17, 2006 0:23:50 GMT
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darynalexander
100+
will probably give you some sort of disease.
Posts: 179
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Post by darynalexander on Dec 17, 2006 0:40:55 GMT
You must forgive me because this will be the first time I ever solder anything, let alone use the word. My Canamp will be here in a few weeks, and I plan on getting the most out of it (I'm not keen on special editions and the like).
I was planning on using the Panasonic 35v 10000uF you were talking about earlier, PinkFloyd. Along with uf4007's and Elna Silmic II"s. Would it make much of a difference if the Silmics were 25V instead of 35?
I looked for heatsinks, but couldn't find any in that size (again, new at this. pretty dumb). I'd also be interested in swapping resistors, but honestly don't know what type/how many to get.
Thanks for the information, all.
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Post by harleymileage on Dec 17, 2006 5:15:19 GMT
Mike:
Hello from Pittsburgh, PA. I am going to order parts from Digikey. I believe that I am clear on all but two issues. Would you please advise me Mike?
1. Regarding the 1J63 and 1K63. You stated you would replace with EVOX polyprops OR bypass with small value polypropylenes. I am unclear as to what to specifically order from Digikey. Also, what about any polarity issues during installation? You also mention bypassing all the other film caps for the time being with 4n7J 100V EVOX polyprops. How many, and what specifically do I order?
2. I want to hardwire an upgraded power cord. I take your point about being able to easily reverse the two prong plug if the mains are incorrect but I am just planning to use this at my place wherein the outlet wiring is correct. Is there a way I can be sure I am hardwiring the power cord with the correct polarity inside the Heed as opposed to relying upon listening to what sounds better? I can pull the outlet to identify the specific wires and correctly trace prior to the proper installation.
Thank you Mike for being so generous with your knowledge. You are a great guy!
Harleymileage (Alan)
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 17, 2006 5:27:36 GMT
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Post by PinkFloyd on Dec 17, 2006 15:25:24 GMT
I was planning on using the Panasonic 35v 10000uF you were talking about earlier, PinkFloyd. Along with uf4007's and Elna Silmic II"s. Would it make much of a difference if the Silmics were 25V instead of 35? 25V will actually be better simply due to the smaller size of the capacitor, they should fit in nicely without the need for funky positioning. I used "63V" 100uF Cerafines in my purely as I had them to hand.... they were far too big, the legs were too thick and I had to drill through the board to get them on.... so, yes, 25V 100uF is perfect. Hold on the heatsinks for the time being, the resistors Rick mentioned may be a better bet and they can run without heatsinks. Actually, the stock 5W 100ohms can run without heatsinks, I just fitted a couple because I had them to hand, they're really not necessary at all here.
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Post by harleymileage on Dec 17, 2006 16:27:47 GMT
Rick, Thank you for that great link; it was right on the money!
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 17, 2006 17:06:17 GMT
Glad you found it useful.Many contend AC polarity makes little difference and maybe in their case it does not but I am fully convinced when you deal with the little things system wide from source to output the accumulative of all the "right" choices makes for a system that is so lucid anything introduced into the signal path later is more easily recognized for what it is while with a comprimised system,one that glosses over problems by nature of it being a "wanderer" in SQ (may sound good today on one recording,may sound like crap a day later with a different recording or source) nothing you do can screw it up any more so even suspect gear will sound just fine not being the weak link. just opinion understand and I'm sure you will find opposing views but when something is a cost free "fix" like the above or trying for absolute polarity correctness on the audio signal does no harm to at least try it out then make up your own mind if the accumulative is a plus,a minus or just the same rickmongo like cheap
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Post by PinkFloyd on Dec 17, 2006 20:04:38 GMT
Hello from Pittsburgh, PA. I am going to order parts from Digikey. I believe that I am clear on all but two issues. Would you please advise me Mike? Hi, I'll do my best OK. The 1J63 and 1K63 are 100nF 63V film caps (the yellow ones) I've replaced these with Wima MKS4 100nF 100V and bypassed them with EVOX 4n7 polypropylenes. www.rapidonline.com pt. no: 10-1780 for the 100nF Wima or you can use EVOX polypropylenes 100nF 250V from www.rswww.com part no: 414-7614 The little 0.0047 polypropylenes from www.rswww.com are part no: 544-1412 You can do a few things with the yellow film caps. you can just bypass them with the 0.0047 polypropylenes or you can remove them and fit either the MKS4 or EVOX 100nF polypropylenes. If fitting the MKS4 you can also bypass them with the 0.0047 polyprops. Remember that both the WIMA or EVOX 100nF caps will be larger than the little yellow ones you're replacing so will have to be fitted under the board. I find it best to actually attach the caps onto the board with either double sided sticky tape or a blob of glue and then solder the legs to the pads, provides maximum strain relief. The 47 / 63V yellow cap is 470nF I just replaced it with a 0.47UF 250V and bypassed it on the underside of the board with a polypropylene 0.0047 (4.7nF) www.rapidonline part no: 10-4152 There are two pads for Live / neutral on the board. Looking at the board from the top with the front of the amp toward you (ie: volume knob to the front) the pad that's to the left is for live and the pad to the right of it is for neutral (directly behind the internal fuse) so live to the one on the left, neutral to the one on the right. I haven't got to the 10n yellow caps on the diodes yet.
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Post by harleymileage on Dec 17, 2006 21:11:38 GMT
Rick, you make perfect sense.
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Post by harleymileage on Dec 17, 2006 21:22:17 GMT
Mike, Thanks! Here's a few more. Hope I am not pushing my luck but if you would clarify:
1. Does a film cap have a polarity? If so, can I identify correct placement on the board?
2. Does a polypropylene have a polarity? If so, can I identify correct placement on the board?
3. I understand replacement of a part. I think I understand bypassing a part (but it's a guess!) and I know that I am confused when you state that you replaced a part AND then bypassed it with another. (sorry if this is novice)
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Post by PinkFloyd on Dec 17, 2006 21:46:49 GMT
1. Does a film cap have a polarity? If so, can I identify correct placement on the board? No. You can fit them anyway round. Non polar No. You can fit them anyway round. Non polar Basically I am bypassing the polyester caps with small value polyproplylene caps to give the cap some polypropylene "flavour" Not enough room in places to fit one big polyprop so the next best thing, imo, is a polyester film cap bypassed with a small polypropylene. All bypassing means, in this instance, is you're soldering one cap directly onto the other one in parallel. I'll go and draw a diagram which will make this clear. Mike. So basically you're just soldering one cap directly onto the other so you now have a polyester / polypropylene combo. As I say, this is not essential but something you may wish to play around with. You can also bypass the electrolytics with a film cap, not essential but you can If bypassing say the 100uF electrolytics then try paralleling on two different types of film cap such as a 1uF polyester and a 10nF polypropylene..... nothing set in stone here, just saying you can try it
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Post by harleymileage on Dec 17, 2006 22:38:44 GMT
Mike, I am indebted to you. Thanks!
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Post by PinkFloyd on Dec 17, 2006 22:57:39 GMT
Mike, will you mod the Heed for those who would send you one? If not would you generate a part list or a kit? Thanks. Hi Miguel, The amp itself weighs quite a lot so will probably be quite costly to ship to the UK, the mods themselves are relatively cheap and easy to do so it would really be a case of whether or not people were prepared to pay that much in shipping costs. I'm happy to mod them at parts cost plus a couple of beers but will have to work out the exact cost to ship back over the pond from the UK. If you could weigh yours, add on say 400gram for packaging and find out what it would cost to ship to the UK it'd be appreciated. Obviously fully insured and trackable not standard airmail. Once I'm finished with this one I'll be more than happy to provide a parts list. As I say, there's not that many parts to be changed but those I have changed have brought about incredible improvements to the sound quality, across the board, so let me try these resistors and a few other bits and bobs. When I'm 100% finished evaluating the tweaks I'll provide a comprehensive list with step by step instructions. I doubt I'll be offering a kit, packing capacitors into jiffy bags can become extremely time consuming and honestly not what I enjoy doing. Custom mods at a bread and butter price..... maybe it will depend on the demand. As I've already said, I'll do yours for shipping + parts, it's always good to have a second opinion on the effectiveness of the tweaks and I trust your ears Miguel
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Post by PinkFloyd on Dec 17, 2006 23:08:28 GMT
Mike, I am indebted to you. Thanks! Another thing to buy is a dip8 socket: Handy when it comes to rolling in different opamps. One word of warning, desoldering the existing NE5532 opamp should only be attempted if you're competent at soldering. This is one area where pads can be lifted VERY easily so please don't attempt it if you've never used a soldering iron before. If you're good at soldering / desoldering though the Dip8 socket is an absolute must as it makes chip rolling as easy as pie.... once it's in position it's simply a case of plugging in the opamp you want to try, when you're ready to try another you just unplug the existing one and plug the new one in..... essential if you're a seasoned roller
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 17, 2006 23:20:14 GMT
welllllll.........um.............OK,I'll shoot it out there and see if it sticks to anything While not directional in a traditional sense where there is an actual "+" and "-" polarity film caps ARE directional in that one side is attached to the foil so at the minimum you want to orient your caps so that the left and right channel pairs are inserted in the same direction (usually a stripe at one end of a cap and if not have all writing face the same direction so when looking from the side of the pcb you either se ALL writing or ALL blanks ). There is also a school that says you should attach the foil end to the point where the ground potential is at its lowest which is the upstream end of the signal path,where it comes from not where it is going to.Even those who follow this rule of thumb find with certain capacitors they actually sound better "backwards" so it is a good idea to try them both ways if at all possible.either way,same direction no matter what direction is the way to go
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Post by PinkFloyd on Dec 17, 2006 23:42:54 GMT
Of course, that's the done way, goes without saying, just the same way I like to "dress" screws when I tighten something up but Rick, there's nothing on a film cap which says "foil end" and nothing in the spec sheets to suggest they should be orientated in a particular direction.... I hear what you're saying but think we're entering into the pedantic zone on this one.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 18, 2006 0:50:26 GMT
actually Mike many types have a small "slash" or band at one end to note foil connection some use a colored wire cover like the Auricaps and others you have to just go on faith that the writing is consistant with orientation (usually is though) and if you check the manufacturer sites and download all the literature you will find many times they DO actually mention cap orientation. the thing is,the little shit that can make a difference is totally lost if there is already a boatload of system infractions elsewhere because it is always the MOST that covers up the least with in this case low level resolution being the least and blurred imaging or wandering notes the most. you know me Mike and know I don't fall for all that audio vooddo crap and know i try and use sound principals or a common sense low budget approach to audio but when there are things we can do for FREE like using proper grounds (more than just HUM in an improper ground buss),proper layout,proper wiring for part of circuit path,proper parts orientation (ALL caps are directional,no resistor is),good vibration and microphonics isolation............ you add all the little shit up and do it system wide then try and get a positive phase on EVERY OUTPUT then clean up the AC Mains feed and you reach a point,and it took me a damn long time to get there bud,where you introduce something new and any flaws are easily recognised for what they are hence easier to correct. I don't much worry about tonality thinking we have NO IDEA what a recording is meant to sound like TONALLY unless we have the exact same monitors but I DO worry about loss of information,extraneous noises (hiss,hum,RFI,mains induced crapola) and an image that wanders or widens when the music get loud then shrinks as the voltage levels decrease and that means precise left/right channel matching (far more important to have stereo PAIRS of a thing than the exact value ) and why I make it possible in my own system to flip overall signal polarity AND trim the left/right balance. so bottom line,yeah,i personally beleive it makes a difference if it is followed consistantly from front end to transducer but that it makes less of a difference if only certain points in the signal path are corrected. it also come down to being free so why take a chance on being off base when the solution is such an easy one to implement ?
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 18, 2006 1:35:48 GMT
From Vacuum tube Valley (yup,the folks who produce the magazine ) "Capacitor Installation Tips: Remember to connect the inner foil side facing the output. In coupling caps, this means connecting the inner foil to the grid of the output tube and the outer foil to the plate of the driver tube. On some caps, the color of the wire indicates the inner foil side, on some the inner foil is marked and on others it is typically the right side of the cap when reading the value. On older caps, the outer foil is indicated by a band around the cap."www.vacuumtube.com/capacito.htmand no,I will NEVER pay close to a C-Note for a single 1uF cpacitor.Just aint gonna happen ;D
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