xerxes
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Post by xerxes on May 3, 2006 17:58:34 GMT
Having messed around and built a couple of silly things like crossfeeds and battery power supplies I fancy having a go at something a bit more ambitious.
I've never really tried valve gear, so I'd quite like to build something tube based. I have pretty low efficiency, 86dB/w monitor type speakers, so a low power, sub 50w per channel, integrated or power amp is a bit of a non starter, so perhaps a headphone amp.
I'd like something that is fairly straight forward to build, even for a relative novice. Not too expensive, but something that will sound reasonably good, at least on a par with the WNA amp and that will give me a flavour of "the valve sound", if there is such a thing, to contrast with the solid state stuff I'm familiar with.
I don't mind whether it's a kit or a PCB, provided that the PCB only route doesn't involve sourcing lots of hard to find parts from all over the world and ending up costing a fortune for postage.
Any suggestions?
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rickcr42
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Post by rickcr42 on May 3, 2006 18:40:41 GMT
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Stormy
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Advocates putting smokers in a "Sin Bin"
Needs to learn to keep his big mouth shut.
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Post by Stormy on May 3, 2006 19:08:57 GMT
My supervisor at work (the pro-ROHS fiend that everybody hates) pointed me at World Audio during my interview for my job. I was interested, but at the time my soldering wasn't up to much, and I'd kind of set my heart on an X-Can of some description (cheaper, for a start). I'd like to know how the HD-83 compares to its MF rival(s), but I'm not sure I want to start down Mike's dark "can't move for headphone amplifiers" path. I suppose I ought to resign myself to the fact that I'm a hoarder and it's going to happen at some point!
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rickcr42
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Post by rickcr42 on May 3, 2006 19:31:52 GMT
pretty much. just by posting in the thread tells me you are screwed and will at some point bite the bullet BTW-I like the WAD site update a lot.I always felt it was very lacking which did not inspire me into wanting any of the products even though likely very good products/kits.
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xerxes
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Post by xerxes on May 4, 2006 0:45:06 GMT
Hi Rick, I like the look of the WAD HD-83 kit, no Manhattan skyline. And it doesn't look too complicated from the internal shot (famous last words ;D): I just wish I could find a bit more information on how it sounds. In any case, I think I'll fire off an E-mail to them and ask what else is required to complete the kit.
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rickcr42
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Post by rickcr42 on May 4, 2006 1:18:26 GMT
Actually it is a two stage topology but because the tubes have both a triode (front end gain) and a pentode (power stage) in the same envelope the appearance is of simplistic. Notice the output is trafos coupled and that is a nice touch meaning they paid attention instead of just rushing out with a design to have a headphone kit offering.Iron is not cheap either Think ASL Wave-8 for a direct triode/pentode "Spud" amp (one tube so single tubor.A tubor is also a potato thus SPUD amp ) type comparison or even one of the many Single ended EL84/6AQ5 based designs with a triode front end . I don't KNOW how this amp sounds but have a suspician being familiar with how it works that it does. Plus the price is not too shabby and it is definately not ugly unless you are the type that needs to SEE the tubes as many are even though about the worst possible way to build an amp....................
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xerxes
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Post by xerxes on May 4, 2006 15:48:12 GMT
Well most of that is Greek to me Rick, but it's encouraging that you think that the kit appears to represent good value for money. While trying to find out a bit more about it, I did come across this: homepages.tcp.co.uk/~nroberts/article84.pdfThe component count looks fairly low and the PCB layout is uncluttered, so it should be relatively easy to assemble for even the most ham-fisted soldering iron user. ;D It's a shame they made the case wider, the old style narrower box would actually have suited me better, ho-hum. I wonder idf it's available without the case. ;D
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rickcr42
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Post by rickcr42 on May 4, 2006 17:33:53 GMT
The wider box could be a blessing if the old one had hum from the close proximity of the power trafos to the output trafos.Using a toroid means you get less "in the box" radiated hum and noise with a traditional or even split bobbin power transformer having no shot at being in a box that size unless there was serious shielding (mu metal $$$) I personally am no fan of the toroid which is extremely sensitive to any DC riders on the AC mains (and yes it is there),can take off and buzz for no apparent reason and does not filter out mains crap nearly as well as does a split bobbin type but things what they are it is expected if the equipment is to be taken seriously and/or has the PS in the same box for cost. Not knocking the amp,it looks to be a real bargain,but making a personal observation on taste
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Post by PinkFloyd on May 4, 2006 20:18:55 GMT
radiated hum and noise with a traditional or even split bobbin power transformer having no shot at being in a box that size unless there was serious shielding (mu metal $$$) Please don't laugh Rick. You know the baked bean tins with the grooves on the side? OK, cut one of those to size using one of the grooves as a guide for the saw, cover the trafo with it and araldite onto the PCB. Works wonders and if you buy the beans at Lidl the trafo cover will only cost you 9 pence "and" you get to eat the beans too. If the bean tin is too small then shop around, pineapple tins or sweetcorn tins........ you're sure to find a size that will fit. This cheapskate tweak brought to you in conjuction with LIDL, the smarter place to do your shopping where the most expensive thing in the shop is the pound you put in your trolley and, shit, you get that pound back when you park your cart!!
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xerxes
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Post by xerxes on May 4, 2006 20:28:15 GMT
When you're too pikey for Asda!
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rickcr42
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Post by rickcr42 on May 4, 2006 20:49:39 GMT
Not if I don't look I won't !No way I could live with myself I would rather continue the "two box" method which allows guys like me to test new power supplies without a total circuit re-design.just plug 'er in and wait for the magic smoke to escape
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Post by PinkFloyd on May 4, 2006 21:08:19 GMT
Seriously man, that wasn't a joke, a tin can cut in half and covering a toroid is gooooood! You can even make flaps at the bottom, punch them and attach the tin cover via bolts through the PCB..... all for pennies and "spray" them and you'd swear they were custom made jobs I'll put one together and take a pic and you will "gasp" with delight I promise you
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on May 4, 2006 21:56:52 GMT
I was actually joking a bit.I do use split bobbins in casing way too small but use a proper grounded shield and careful placement. It never ceases to amaze me how shifting the angle of a transformer in relation to the active circuitry or slightly moving a single wire can make an amp go from humming bastard to dead quiet. I prefer two box but sometimes just not practical (shelf space,added cost of the second box plus connecting cable).
I also use split bobbins for heater supplies feeling a little extra filtration never hurt anyone rserving the B+ trafos LV secondary strictly for rectifier tube heaters but now we are talking about some serious power section real estate for even a lowly line stage once the choke is added in to the equation (plus it weighs a LOT)
Still better than the alternative of "toroid" though.They flat out piss me off and if not for the "cool look" combined with customer expectation/ad copy I am not sure if we would see them in anything but high power SS power amplifiers
They offer little mains "crud" filtering,start up way too quick for many devices (surge current),HATE DC on the AC so the damn thingssound like there is a nest of honets inside the amp when DC hits the primary (which we ALL have in our homes at some point during the day)
Using a toroid means :
1-Block DC at the primary 2-Slow down the AC to the primary 3-Slow down the AC from the secondary to save the recifiers from stressing out (the next stage,the electrolytic is a dead short on startup) 4-RFI filters to both the primary and secondary sides 5-more actual power supply bypassing
in short way more work than the returns suggest are a good tradeoff yet used in just about every single piece of high end audio gear made.
then again maybe it is just me who is cursed with "Toroiditis" since many apprently good sounding amps DO use them..........
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FritzS
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Post by FritzS on Jun 6, 2006 13:47:59 GMT
For all who can read german: ITM CapoTube www.praktiker.at/prjkha01.htmThe only way to get the schema and description is to pay ITM praktiker No. 11 / 2005 and N0. 1-2 / 2006 - for case description cantact praktiker. "Bauanleitung in ITM praktiker Nr. 11 / 2005 und Nr. 1-2 / 2006. Bauanleitung für Gehäuse folgt." The "ITM CapoTube" developer Wolfgang Paltauf, Rainer Thöress, Alexander Seidler are some of the best engineers for tube amps in Austria/Germany
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jun 6, 2006 23:54:09 GMT
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