qwerter Posted September 7, 2012 Posted September 7, 2012 (edited) I am going to replace capacitors in my preamp (yaqin ms12b). They are 1 uf. Is the voltage (200 or 220v) critical? Thanks. Edited September 7, 2012 by qwerter
Guest Muon Posted September 7, 2012 Posted September 7, 2012 They are rated at 275vac by that schematic, and while I can't see what the caps are getting across them, I would just use 1uf caps that are the same 275vac or higher. Most film caps come in that sort of value, but remember those stock caps are spec'ed in AC voltage, so if the replacements are rated in DC the value will be noticeably higher.
qwerter Posted September 7, 2012 Author Posted September 7, 2012 Thanks datafone, it is all greek to me. I can operate the soldering iron, but that is where my electronics knowledge ends. What might happen if I replace them with 200v? What is the potential problem?
LogicprObe Posted September 7, 2012 Posted September 7, 2012 The problem would be failure. They have a tolerance built in so they may work for a while.
qwerter Posted September 8, 2012 Author Posted September 8, 2012 In other words, do you say that I can't use anything below 275vac?
Guest Muon Posted September 8, 2012 Posted September 8, 2012 (edited) That's correct, and often the voltage most of the time will be a fair bit lower than the rated component, but you can have surges at power on and off that are higher. So best to sub with the same or higher voltage values, also consider that a cap that is rated at 275v in AC will handle higher voltages in DC, so if rated in DC go for something like 500vdc or 600vdc capacitors, 400vdc or 450vdc may be OK, but best to play it safe. That's not an accurate comparison of AC & DC ratings, but ya' get the idea. Edit: Geez...does that make sense I suck at writing Edited September 8, 2012 by datafone
RoHo Posted September 8, 2012 Posted September 8, 2012 Total sense, Datafone. I think a "conversion" factor of about 1.4 is safe when comparing AC vs DC cap voltage ratings. A 400VDC cap would be fine. Also the schematic shows the main PS caps are 350V rated, use that as a guide.
Addicted to music Posted September 8, 2012 Posted September 8, 2012 Not only voltage is important, size is the other issue, the higher uf and voltage, the cap increases in physical size so you have to ensure to take physical dimension into consideration. Changing to MKPs can get big, very big!
Guest Muon Posted September 8, 2012 Posted September 8, 2012 Wouldn't change the capacity of the caps, but yeah, some caps of 1uf can be big compared to the stock caps....especially Teflon's
Addicted to music Posted September 8, 2012 Posted September 8, 2012 Wouldn't change the capacity of the caps, but yeah, some caps of 1uf can be big compared to the stock caps....especially Teflon's Expensive, need to be Bill Gates to get those Teflons
qwerter Posted September 8, 2012 Author Posted September 8, 2012 Thanks guys. Will have to find some caps with the right voltage.
Guest Muon Posted September 8, 2012 Posted September 8, 2012 Clarity Cap ESA, Obligatto MPK and Mundorf Supreme are all reasonably priced caps.
Monkeyboi Posted September 8, 2012 Posted September 8, 2012 Albeit the caps in question are rated at 275 V a.c., the powersupply capacitors for the HT supply are only rated at 330 volts, suggesting that the hghest voltage above the 0v rail (earth) couldn't be higher than this. 275v a.c. rating is equivalent to a tad under 780 volts d.c. What type of capacitors are currently in the posistions you intend to replace? Most stock capacitors with 275v a.c. rating are normally Class X2 mains suppression capacitors with self healing dielectrics. These would be an unusual choice for audio coupling applications. If you were to play it overly safe you could use capacitors rated at 1000 volts, but IMHO and in consideration of the circuit voltages, it would be a bit of an overkill. Anything rated over 350 volts would work just fine. Just ensure they are mounted clear of heat producing devices to prevent premature failure. Cheers, Alan R.
LogicprObe Posted September 8, 2012 Posted September 8, 2012 Just out interest, why have you decided to change them and what caps are in there now?
qwerter Posted September 8, 2012 Author Posted September 8, 2012 The original capacitors are some cheap chinese ones. There are a lot of mods done to these preamps and they say that the biggest improvement comes from replacing the above mentioned 6 caps.
Addicted to music Posted September 8, 2012 Posted September 8, 2012 (edited) If you dont use vinyl you you can save by just changing just two 1-2uf caps on the o/put of the circuit. If the stock caps have MKP letters marked on them, then I really see no benefits in doing so, Some of the expensive caps with audiophile names are just rebadged and probably come from the same factory! Edited September 8, 2012 by pchan
Monkeyboi Posted September 8, 2012 Posted September 8, 2012 If the stock caps have MKP letters marked on them, then I really see no benefits in doing so, Some of the expensive caps with audiophile names are just rebadged and probably come from the same factory! You'd be surprised at the placebo effect an expensive audiophile brand component can have. Many audiophile brand "manufacturers" are reluctanct, if not down right secretive when it comes to revealing what makes their part superior to a competitors, even if the competitor is a regular well known reliable brand. I often wonder what significant differences exist between capacitors of the same type from one manufacturer to the next. In electronics, choosing the right type of capacitor for the application is IMHO more important than the brand alone. Of course it would be important to chose one from a manufacturer with good quality control and high manufacturing standards. IOW avoid the no name cheapies. Cheers, Alan R.
qwerter Posted September 8, 2012 Author Posted September 8, 2012 Some people had great results with Russian PETP K73-16 1uF Capacitors. They can be bought for peanuts (http://www.ebay.com.au/itm/1uF-5-400V-PETP-K73-16-Capacitors-10-pcs-NOS-/251009557854?pt=LH_DefaultDomain_0&hash=item3a7155e55e). I will try and will let you guys know how it works out.
Addicted to music Posted September 8, 2012 Posted September 8, 2012 Some people had great results with Russian PETP K73-16 1uF Capacitors. They can be bought for peanuts (http://www.ebay.com....=item3a7155e55e). I will try and will let you guys know how it works out. Give them a miss, check this out instead: http://www.humblehomemadehifi.com/Cap.html knock yourself out MonkeyBoi This guy gives PEPT a very average rating. Stick to the MKP or anything that is MKP.
qwerter Posted September 8, 2012 Author Posted September 8, 2012 This amp is not in my main system, so will be great for experimenting with caps!
qwerter Posted September 8, 2012 Author Posted September 8, 2012 This guy gives PEPT a very average rating. I couldn't find him talking about PEPT??????
Addicted to music Posted September 8, 2012 Posted September 8, 2012 (edited) They come under the brand WIMA MKS, roll down to the end of the article of the link http://www.humblehom...fi.com/Cap.html Or here: WIMA MKS 4 100VDC – 10% tolerance Technical specifications (according to manufacturer): “High volume/capacitance ratio; Self-healing; Typical applications for general DC-applications e.g. bypass, blocking, coupling and decoupling. Dielectric: polyethylene-terephthalate (PET) film; Capacitor electrodes: vacuum-deposited; Encapsulation: solvent-resistant, flame retardent plastic case with epoxy resin seal; Terminations: tinned wire.†Sound: Good overall neutral sound that is never harsh but does have a bit of a “plastic†sounding treble. The top-end is silky and smooth. Imaging is a bit flat with not much depth. In direct comparison to the Vishay MKT1822 there is more transparency but less coherency. Verdict: 6 If you really want to notice an improvement use anything with MKP. Why MKP? High dv/dt lower absorbtion rate almost all are self healing The main 3 characteristic that determind the quality of a capacitor use in signal pass through. If you cant find polystyrenes(MP) use polypropolyne(MKP) Even Silicon Chip are documenting there find that using MKP instead of traditional ceramics for psu decoupling and RF reduction, switching to all MKP actually reduces distortion and enhances the S/N ratio of there latest ULD 3 power amp modules. This was a total turnaround on the use of MKP before they tested them. Going from electrolytic to MKP using the same uf, opens up the soundstage, better clarity and transpency, voices are more natural and the timbre in intruments are more defined, its like a veil has been removed and the increase smoothness reduces the edginess. the increased dv/dt gives you increased PRAT. Say away from PETP if you want to notice an improvement, you maybe better off with the stock originals Edited September 8, 2012 by pchan
LogicprObe Posted September 8, 2012 Posted September 8, 2012 Going cheap! (but there's only 5 of them) http://www.ebay.com.au/itm/5pcs-long-copper-leads-yellow-Axial-Polyester-Film-Capacitor-1-0uF-630V-amps-/160878592207?pt=AU_B_I_Electrical_Test_Equipment&hash=item25751c80cf
Addicted to music Posted September 8, 2012 Posted September 8, 2012 Going cheap! (but there's only 5 of them) http://www.ebay.com....=item25751c80cf Logicprobe, see if you can find some MKPs cheap on ebay
LogicprObe Posted September 8, 2012 Posted September 8, 2012 Logicprobe, see if you can find some MKPs cheap on ebay I was only looking for high voltage caps.
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