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Post by jdn on Oct 23, 2007 18:46:14 GMT
I have looked through the DIY resources sticky and looked through a few of the websites .... Rapid, RS, Farnell, Maplin etc etc but can't seem to find what im looking for.
I am going to carry out the B-tech BT928 mod and want to use some nice bits. From what i have been told (im a bit of a newbie) the following are good capacitors:
Chemicon - KZE/KZH Rubycon - MBZ Nichicon - Any series with "H" as the first letter. HZ being the best. Panasonic - FM
Apart from the Panasonic FM's i can't find any of the others, and would like to try something new. (I have built gainlcones and always used FM's so its getting a little dull).
Cheers for help in advance.
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Deleted
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Post by Deleted on Oct 23, 2007 21:30:34 GMT
jdn Send Pink Floyd a PM. It is quite likely that he can supply some of them, or alternatives that he recommends.
SandyK
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Post by PinkFloyd on Oct 23, 2007 22:28:05 GMT
I have built gainlcones and always used FM's so its getting a little dull What's getting dull? The SQ? Or is it just the look of the capacitor that's getting a bit dull? You may find the caps you have listed at uk.farnell.com/jsp/home/homepage.jsp I think the info you have gleaned is from computer forums such as forums.extremeoverclocking.com/showthread.php?t=178236 (check thread #6) and not from audio forums... what's good for a computer is not necessarily good for audio usage when it comes down to SQ.
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Post by jdn on Oct 23, 2007 22:38:27 GMT
Haha, never even heard of extremeoverclocking.com before now.
I did some research and came across the Nichicon KZ which looks like it would be good, but again, i have no idea where to get them from.
I did e-mail a couple of places in the vein hope they can help, but i think they are mass distributors and not for likes of me!
What would you recommend Floyd?
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Post by PinkFloyd on Oct 23, 2007 23:00:26 GMT
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Post by PinkFloyd on Oct 23, 2007 23:03:03 GMT
What would you recommend Floyd? Save your pennies mate. I REALLY must update (wipe) parts of my website
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Post by PinkFloyd on Oct 23, 2007 23:06:33 GMT
If you want to throw money into the BT-928 contact "mayday" (grotto member) jaws_of_steel@msn.com he has apparantly taken it to the "max" ;D
<message to self.... remove B-Tech pages from website ASAP>
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Deleted
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Post by Deleted on Oct 23, 2007 23:07:26 GMT
jdn
You just can't slot a particular type of capacitor in any location and expect an improvement in SQ. Experienced people like Mike choose the type and make of capacitor/ resistor to suit the actual location, based on what they feel needs improving, AND hands on experience of the particular piece of equipment.
SandyK
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leo
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Post by leo on Oct 24, 2007 0:11:12 GMT
I missed this thread. Anyway my advice is stay clear of a lot of the low esr caps in analogue circuits especially Rubycon MBZ, these are good caps but you really need to be cautious where you stick these, not just problems in the circuit but can take the skin off your teeth regarding sound the Panny's FM's and FC's are also excellent caps but you can't expect them to work well in all gear, unfortunately modding a particular piece of gear for the first time is not an easy task, Mike will know something like X-cans inside out and probably spent many hours fine tuning it. Nichicon KZ's are not bad, I find these can be a little too smooth and personally prefer the cheaper Fg series over these, again it depends where they are being used
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Post by jdn on Oct 24, 2007 7:04:18 GMT
Cheers for the advice so far guys. I understand what you are saying, and im in no hurry to just throw something together. This was supposed to be a bit of fun, cheap amp so if i cock it up it i don't mind that much, learn some bits, and at the end of it have something nice to listen too. I enjoy taking things to pieces and 'messing' with them, this just happens to be the first real time im trying it with such a device.
I am of course going to replace the OP amp .... forgot to mention that.
Floyd, i don't think you should wipe this from your website, it is a good little project for beginners. Technically its not that complicated to complete, but as sandyk says, its the choice of capacitors than needs the thought.
Im not expecting to take this to the 'max' or make out like im going to make it sound a thousand pounds, id just like to 'customise it' have some fun in the process and enjoy it after (while i write many hundreds of hours worth of coursework and dissertation).
So all your help is really appreciated, and i hope you don't mind bearing with me just a bit longer.
Cheers!
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leo
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Post by leo on Oct 24, 2007 23:38:03 GMT
If theres some form of circuit diagram it gives us a better idea and will help to give you advice/idea's to try
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Post by jdn on Oct 25, 2007 9:21:20 GMT
Ok cool, there seems to be absloutely nothing online, so once it arrives ill see what i can do. (Cash flow has just stopped dead so won't be until the beginning of next month now) Damn i hate being a sutdent.
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Post by mayday on Oct 25, 2007 21:05:37 GMT
The Pana FM's are good, so is os-con, I used Black Gates from www.acoustic-dimension.com and also the superb Kiwame resistors. I'm using AD827 or AD8066 op-amps. Thinking of trying a new one LM4552 I think it's called, but I might be mistaking. I've also raised the BIAS current in the op-amp using resistors. One of the most rewarding updates is to put film caps, like WIMA across all lytic caps and from from(on the opamp) V+ in to stargnd and V- in to stargnd or closest gnd point on PCB. I improved the wallvart by adding a bigger cap and better diodes, but then I jus made a stabilised PSU myself using a oversized trafo, byv27-150 diodes as rectifiers, snubbed them, 4400uF pana FC as bank and then regulated it using an LM317 regulator. All lytic caps with film caps across, Wimas, also the diod in the b-tech was replaced by a BYV27-150 and snubbed. And of course I put a fuse int the PSU.
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Post by mayday on Oct 25, 2007 21:07:08 GMT
All filmcaps I used were 0,1uF
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Post by mayday on Oct 25, 2007 21:33:32 GMT
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Post by mayday on Oct 25, 2007 21:35:50 GMT
Alps blue and AD8066
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Post by mayday on Oct 25, 2007 21:43:08 GMT
There's obviously a lot of money in my b-tech, but I thought I'd be fun to go all out. And it Does sound GOOD. Many complain about a 50hz humming, this is from the wallvart. I also advice you to be careful when soldering on this PCB, since it's basically crap and solderislands will come of if not careful.
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mrarroyo
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Post by mrarroyo on Oct 25, 2007 22:13:33 GMT
mayday, would cleaning the op-amp sockets and the surrounding area lead to a better sound?
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Post by PinkFloyd on Oct 25, 2007 22:39:56 GMT
If theres some form of circuit diagram it gives us a better idea and will help to give you advice/idea's to try best I can come up with Leo: Lose the tone control, just desolder it and also lose the two green ceramic caps adjacent to it. I have contacted Jonas "Mayday" and hopefully he will be over to advise further, he "maxed" his out and I'm sure he won't mind me hotlinking to these photos:
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Post by mayday on Oct 26, 2007 9:02:53 GMT
mayday, would cleaning the op-amp sockets and the surrounding area lead to a better sound? Please explain what you meen, remember, English is not my first language.
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Post by mayday on Oct 26, 2007 9:05:50 GMT
Pink: I removed the brown/orange ceramics as well. Of course I don't mind, feel free to use the pics.
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Post by mayday on Oct 26, 2007 9:08:31 GMT
heatsink is used for cooling memry chips on graphics card, but is perfect for this purpose. Not necessary if you don't raise bias current. One advantage though is that if you connect the heatsink to gnd, you have more or less shielded the opamp.
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leo
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Post by leo on Oct 26, 2007 11:54:43 GMT
It looks like an oversized Cmoy So I presume you have resistors on the op-amps output to its supply rail? instead of resistors why not use J-fets with a resistor through them for setting the current. Are those 47uf caps for decoupling or the output coupling? An op-amp like the AD827 likes a quality decoupling arrangement to sound its best
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Post by mayday on Oct 26, 2007 12:15:42 GMT
Resistors are pin1 -> pin4 and Pin7 -> Pin4. I like this arrangement, since I can just remove the socket to change bias back. Sockets are piggybacked. Decoupling is done w filmcaps on the underside of the PCB. Like to easily be able to change opamp without touching anything else...convinient.
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Deleted
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Post by Deleted on Oct 26, 2007 12:20:59 GMT
Perhaps there now isn't much more left to extract from the basic circuit. Have you tried it with high performance regulated PSU ? SandyK
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