"R.M" brand capacitors

[japlytic]

In another DVD player I fixed, I found some "R.M" brand electrolytic capacitors (CD110 series, used by more than one Chinese manufacturer). They were not bulging nor were they causing any problems, but I wanted to know if anyone has seen such a brand. (Ignore the Daewoo units, they were all good)

(A little off topic, I found an 'LTEC' capacitor in the SMPS - I replaced it!)

[markiemrboo]

Re: "R.M" brand capacitors

Sorry for digging up a fairly old thread (I am not sure if you guys really mind, but the other computer forum I visit does. Personally I dont see much of a problem with it)

I just opened my amp and they're *all* R.M brand caps in there. I was about to come and ask about the quality and whether I should bother replacing them. Don't suppose anyone knows what they're like?

Google says...

Capacitors suit high pin count IC applications., Taiyo Yuden USA, Inc.
The extremely small size of the RM Series capacitors results in higher component placement density, efficiency and PCB real estate savings, an especially ...

I know Taiyo Yuden are quite well known for their high quality DVD dye stuff... but how about caps?

Also, my speaker crossover's have "Sounder" caps, with NP written on the end. I assume this means they're non polarity caps? Are Sounder any good?

[willawake]

Re: "R.M" brand capacitors

i doubt if they are the same. the TY caps are a series of ceramics

these are probably yours http://www.rme.cn

[markiemrboo]

Re: "R.M" brand capacitors

i doubt if they are the same. the TY caps are a series of ceramics

these are probably yours http://www.rme.cn

Ok, so are they any good? By the pictures on the website I think they might be the KLE series... http://www.rme.cn/enhtml/kle-1.htm ... Thought I guess pictures don't necessarily mean much. I didn't think to look at the model number when I had it open. Oops! They're the only black can ones with a stripe down them on their site though.

If I am going to be replacing them I can get a mix of Panasonic and Elnas from Farnell. Are the chosen ones below probably suitable replacements?

Original: 8x R.M - 50v, 2200uF, 85C
Replacement: 8x Panasonic FC - 50v, 2200uF, 105C

Original: 10x R.M - 63v, 100uF, 85C
Replacement: 10x Panasonic FC - 63v, 100uF, 105C

Original: 2x R.M - 50v, 1uF, 85C
Replacement: 2x Elna RJH - 50v, 1uF, 85C

Original: 6x R.M - 16v, 47uF, 85C
Replacement: 6x Elna RE3(?) - 16v, 47uF, 85C

Original: 1x R.M - 16v, 10uF, 85C
Replacement: 1x Elna RE3(?) - 16v, 10uF, 85C

Original: 2x R.M - 50v, 47uF, 85C
Replacement: 2x Elna RE3(?) - 50v, 47uF, 85C <-- OR --> 2x Panasonic NHG - 50v, 47uF, 105C

[linuxguru]

Re: "R.M" brand capacitors

Yes, they're all good replacements. Just check that none of the Elnas goes into a location which could get very hot - for example, next to an output power transistor.

[markiemrboo]

Re: "R.M" brand capacitors

Well i've placed an order for all those. I needed some other bits to fix a broken USB port on another computer, and they have a minimum order of £20. Figured I might as well

I can say one thing. The 2200uF ones (I assume they're for the power supply or something) seem to get rather hot. They were still hot (not just warm) to the touch at least 5 minutes after the amp being turned off! Those are fairly close to a big heatsink. I suppose the heatsink is where those transistors are? I dunno

[markiemrboo]

Re: "R.M" brand capacitors

http://www.rme.cn/enhtml/cd110.htm

They're *all* R.M CD110 series caps. Could someone tell me if they're any good? Whether it's worth replacing them?

The site says

High Characteristics

Suit for use in electronic complete sets of high quality.

But, hm!

[willawake]

Re: "R.M" brand capacitors

its worth a try but dont expect something spectacular

i would do them first and then decide if it is worth doing the rest.

Original: 8x R.M - 50v, 2200uF, 85C
Replacement: 8x Panasonic FC - 50v, 2200uF, 105C

personally i dont want china crap in any of my units

[markiemrboo]

Re: "R.M" brand capacitors

its worth a try but dont expect something spectacular

i would do them first and then decide if it is worth doing the rest.

Original: 8x R.M - 50v, 2200uF, 85C
Replacement: 8x Panasonic FC - 50v, 2200uF, 105C

personally i dont want china crap in any of my units

Yeah, those are the ones I was planning on (and did) first. I did three smaller ones then decided I needed music for a while!! I might do a few more tomorrow.

I'm thinking I am hearing more detail in the high mids that I wasn't hearing before, but that could be because I am listening harder or something. I don't really know. It's quite strange I swear I am hearing details that I wasn't before though.

[linuxguru]

Re: "R.M" brand capacitors

It's entirely possible that there's an audible improvement, but there are some caps that contribute far more than others. Generally, larger interstage-coupling, bias-stabilisation bypass, driver bootstrap, and power output coupling caps make much more difference than changing a bunch of power-supply decoupling/bypass caps.

Well-designed audio power amps have very high PSRR (Power Supply Rejection Ratio) anyway, so improving the supply bypass to suppress AC hum isn't going to make much of a difference. Every now and then you read about some clueless modder on audiophile forums who's replaced all the caps in the power supply with Black Gates or Cerafines, and claims that there's an audible difference. Maybe, but the returns are marginal compared to the signal path.

[markiemrboo]

Re: "R.M" brand capacitors

It's entirely possible that there's an audible improvement, but there are some caps that contribute far more than others. Generally, larger interstage-coupling, bias-stabilisation bypass, driver bootstrap, and power output coupling caps make much more difference than changing a bunch of power-supply decoupling/bypass caps.

You seem to know your stuff I've heard some of those different.... stages.... before, but I don't really know how to tell what caps do what in an amp. I suppose you kind of have to know a bit about how it all works and stuff.

If possible, could you take a lookie at the picture I have attached and try and guess for me what I am actually replacing? The pink circle is ones I have already changed (though in the picture the smaller caps in pink are still actually the originals, I didn't take pictures of the replacements there yet). The big caps there are 50v, 2200uF. The smaller ones there are 63v, 100u. I intend to replace all of the smaller ones in the pink circle and all of the ones in the yellow circle. Can't remember what the values of the yellow ones are, but I think either 50v, 47uF or 16v, 10uF.

Thanks!

The picture doesn't show the whole PCB, so it might be difficult to tell what does what? I can get a bigger overview picture if that would be better?

[willawake]

Re: "R.M" brand capacitors

it would help if you posted a pic from above of the whole board and then some more closer pics of each section.

[linuxguru]

Re: "R.M" brand capacitors

The large Panasonic FCs that you've put in are most probably the main PSU filter caps - there's nothing wrong in changing them, and you'll probably have better surge current capability. The smaller 100uF, 63v are also probably related to the PSU. My earlier peeve was the practice among many audio modders of indiscriminately replacing all their caps with expensive snake-oil stuff. Panasonic FCs are not expensive, and they will not be worse than what was already there - you'll be OK.

The ones in yellow are probably in the signal path, if they're in input circuitry or in circuitry related to the volume, bass or treble controls. You can safely replace them with Elna Rxx or Panasonic FC, and it definitely will not sound worse, and there's a good chance of an improvement.

My suggestion is to replace a few at a time, in carefully identified circuit blocks, followed by a few days of listening tests to determine if it actually sounds better. The human ear is a funny thing, and it perceives certain kinds of distortion as harsh, and other kinds as pleasing. Some of these mods may reduce the Total Harmonic Distortion (THD), but the ear may still perceive it as sounding harsher. OTOH, there are mods that will increase THD, but the ear may find it pleasing. A good ear is capable of discerning non-linearity and hysteresis in capacitors in the signal path.

[markiemrboo]

Re: "R.M" brand capacitors

The large Panasonic FCs that you've put in are most probably the main PSU filter caps - there's nothing wrong in changing them, and you'll probably have better surge current capability. The smaller 100uF, 63v are also probably related to the PSU. My earlier peeve was the practice among many audio modders of indiscriminately replacing all their caps with expensive snake-oil stuff. Panasonic FCs are not expensive, and they will not be worse than what was already there - you'll be OK.

Cool cool

The ones in yellow are probably in the signal path, if they're in input circuitry or in circuitry related to the volume, bass or treble controls. You can safely replace them with Elna Rxx or Panasonic FC, and it definitely will not sound worse, and there's a good chance of an improvement.

While gone I actually replaced all (well, all but two non polarized) the caps on the middle board with the large caps. Here's an overview, as will requested.



Right next to the large 2200uF caps were two little 50v, 1uF caps.



There were also two 16v, 10uF caps next to what looks like two variable resistors.



There's now only six caps left, on two different boards, all exactly the same values. Two of them lie on a large, rather empty board which has "Unity Gain Output Buffer" written on it.



The remaining four are in two seperate little similar looking (but different) circuits, near the bass and treble dials. All of these are 16v, 47uF caps.

My suggestion is to replace a few at a time, in carefully identified circuit blocks, followed by a few days of listening tests to determine if it actually sounds better. The human ear is a funny thing, and it perceives certain kinds of distortion as harsh, and other kinds as pleasing. Some of these mods may reduce the Total Harmonic Distortion (THD), but the ear may still perceive it as sounding harsher. OTOH, there are mods that will increase THD, but the ear may find it pleasing. A good ear is capable of discerning non-linearity and hysteresis in capacitors in the signal path.

Quite an interesting thing to know Thanks for taking the time to write that rather informative post!

[linuxguru]

Re: "R.M" brand capacitors

Thanks for the pics. You can safely replace the remaining caps with Panasonic FC or Elna Rxx.

If you're feeling a little more adventurous for the next stage of the mods, locate all the op-amps (for instance, on the unity-gain buffer, it is an NE5532 8-pin DIP). Carefully remove the NE5532, and put in an 8-pin DIP socket (preferably with machined gold-plated round sockets, Augat or similar). Now replace the NE5532 and listen to the sound carefully. Try an alternative, pin-compatible op-amp, like the Burr-Brown OPA2604A (with JFET inputs) or OPA2132, and listen carefully. The higher slew-rate of the OPAs may improve the highs, as well as the dynamic range, but YMMV.

There are a number of alternatives, but not all are pin-compatible or use the same package. Some may require additional compensation to work stably. Check out this page for more info on audio-grade op-amps:

http://tangentsoft.net/audio/opamps.html

[japlytic]

Re: "R.M" brand capacitors

i doubt if they are the same. the TY caps are a series of ceramics

these are probably yours http://www.rme.cn

The website has pictures of units matching my description.

[markiemrboo]

Re: "R.M" brand capacitors

The website has pictures of units matching my description.

Yeah, http://www.rme.cn/enhtml/cd110.htm <-- those would be the ones apparently. CD110's. Same ones I have got!

Thanks for the pics. You can safely replace the remaining caps with Panasonic FC or Elna Rxx.

Just need to figure out how the boards are removed now then

If you're feeling a little more adventurous for the next stage of the mods, locate all the op-amps (for instance, on the unity-gain buffer, it is an NE5532 8-pin DIP). Carefully remove the NE5532, and put in an 8-pin DIP socket (preferably with machined gold-plated round sockets, Augat or similar). Now replace the NE5532 and listen to the sound carefully. Try an alternative, pin-compatible op-amp, like the Burr-Brown OPA2604A (with JFET inputs) or OPA2132, and listen carefully. The higher slew-rate of the OPAs may improve the highs, as well as the dynamic range, but YMMV.

Sounds pretty cool. I'm reading the NE5532 isn't too bad? I'm also reading that the NE5534 is supposed to be noticably better though.

http://gainclone.com/phpBB2/viewtopi...c7b78404a4c154

I may try that if I can figure out if it's pin compatible with what is already there, and if I can figure out just which one I need to buy. A quick search on Farnell for NE5534 shows 6 slightly different models.

http://uk.farnell.com/jsp/endecaSear...&Ntk=gensearch

There are a number of alternatives, but not all are pin-compatible or use the same package. Some may require additional compensation to work stably. Check out this page for more info on audio-grade op-amps:

http://tangentsoft.net/audio/opamps.html

Thanks for the link

[mdelrossi]

Re: "R.M" brand capacitors

markiemrboo,
I've got an A500 Cambridge audio amp and I will be replacing the Caps as well (I'm having problems with the PS and output on one of the channels).
Did you do any other mods?
How did the sound change?
thanks.
mdr

[willawake]

Re: "R.M" brand capacitors

Last Activity: 09-01-2006 11:33 PM

might have to wait a while for that answer