| SimontY |
Hi everyone, this is probably one for novice modders, like myself.
I decided to try wiring in bypass/additional caps in my amplifier's PSU (Roksan Caspian integrated). These caps were mostly spare/used and are:
-22nf/400v film x2
-8.2uf/400v metal film MKP x2
-180uf/200v x2
-330uf/200v x2
-470uf/200v x2
10 caps in all, about 2,000uf to add to the existing 13,600uf.
The sound:
First impressions are of a cleaner, more sterile sound, uninvolving but powerful.
After some hours of play the sound has warmed up a lot and has more solid and controlled bass than ever before.
Overall, [probably] positive, and free! (because the caps weren't otherwise used)
I am going to try adding 4x 10,000uf to really beef it up, and we'll see what that does for the bass...
-Simon |
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| SimontY |
Some pictures to go with that description....
Here is the amp in question. |
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| SimontY |
| Here is a poor pic of the unmodded internals, you can see the two 6,800uf 50v Aerovox reservoir caps. |
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| SimontY |
| Here is the back of the main pcb, this wasn't much fun to remove, and I really am surprised and pleased the thing still works! |
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| SimontY |
| I used some Shark (or is it Sharc?) 10ga. speaker cable to connect the new caps to the back of the original ones, all the little strands made it a real nightmare job. Oh, that and me being **** at soldering :rolleyes: |
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| SimontY |
| Testing for explosions etc. with the MKP film caps. - bypassing with these seemed to be a big improvement in itself actually, even just with the leads shoved in the wire... ;) |
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| SimontY |
| Testing with the first electrolytic cap. I put newspapers over the open amp and ducked down when turning it on, I get so scared of stuff blowing up or electrocuting me! :) I wired the caps in parallel with the original caps btw, one of each type per side. I must say, the reservoir caps seem to be wired in a funny way, it makes no sense to me! The + side of one is wired to the common ground - maybe someone technical can explain this phenomenon... |
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| SimontY |
| Here are the five 'new' caps on one side. |
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| SimontY |
Here is the lot completed, the caps are glue-gunned on with the loc-tite glue gun seen in the bg. I apologise for the file size for those with old, analogue modems, and I hope at least one person gains a modicum of happiness from seeing this basic mod ;)
-Simon |
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| analog_sa |
| I'd be very surprised if any of these mods improved the sound at all. What a waste of pictures. |
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| SimontY |
Thanks!
(they did) |
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| KevinLee |
Hello Analog Sa,
Instead of being so negative, why not try giving some advice or opinions?
Simonty, I do believe you probably heard a difference. When I parallel caps I have learned to keep the signal path as short as possible and I use only solid core wire inside my projects.
You might also try the 10% rule: You should not add a cap unless it is 10% the size or smaller than the cap you are paralelling.
Experimentation is everything. I would try adding the 8.2uf and 22nf caps first and then listen. You might like what you hear.
Also I have learned from other forum members (Peter Daniel & Peranders) that capacitor quality plays a more important part than sheer size or capacitance.
Good luck and keep us updated.
Cheers
KevinLee:) |
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| moamps |
| quote: | Originally posted by SimontY
I must say, the reservoir caps seem to be wired in a funny way, it makes no sense to me! The + side of one is wired to the common ground - maybe someone technical can explain this phenomenon... |
Your power supply is symetrical (+/gnd/-). Look connection of C2 on pic.
| quote: | Originally posted by KevinLee
Simonty, I do believe you probably heard a difference. When I parallel caps I have learned to keep the signal path as short as possible and I use only solid core wire inside my projects.
Experimentation is everything. I would try adding the 8.2uf and 22nf caps first and then listen. You might like what you hear.
Also I have learned from other forum members (Peter Daniel & Peranders) that capacitor quality plays a more important part than sheer size or capacitance.
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:up:
my suggestion |
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| SimontY |
Thanks for all the advice, it's greatly appreciated. I was intitailly quite upset by ..sa's curt and dismissive remarks, it made me wonder if there was any point in posting here.
KevenLee: I tried the 8.2uf caps alone first, and I believe I heard some improvement (sweeter), I can't say if it was more or less improvement than after putting them all in together. I will bear in mind the 10% rule in the future... though it happens with most of them: 6,800uf>470uf>8uf>22nf. re: quality - I'd like to put BGs in, but for £100/cap or whatever they would be in a PSU, I can't afford/justify the cost!
Moamps: thanks for the diagram, I will have a closer look later, when I'm not at work ;)
tbla: I'd considered what changing those diodes might do, what would it do? Can I assume they aren't good/Shottky diodes in place already? (I can't see those pdfs on this **** pc, again will look later)
I am ordering 4x10,000uf caps, as the cost isn't huge for Samwha 63v units. I initially got the urge to 'beef up' the psu because I felt this amp was always a little too reserved and soft at higher volumes. I guessed improving/enlargening the reservoir might add some welly - it worked for my sub's plate amp which I tried first...
Thanks for your time, and sorry about the pics, I realise I went ott, now that I am on quite a slow pc!!
-Simon |
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| tbla |
| your amp will sound cleaner, easier, quicker, better bass - more musical.......and btw when you choose to put more caps in your amp, the inrush current (when starting up) could damage the original rectifiers.......:RIP: |
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| deskmate88 |
>>I was intitailly quite upset by ..sa's curt and dismissive remarks, it made me wonder if there was any point in posting here.
Please don't be upset. Sa's comments like that is not welcomed nor a norm on diyaudio. Sa just forgot that he used to be a beginner also. Usually people are very helpful here.
For your mod, just a few points:
1. keep your wires to the additional filtering caps as short as possible, and use solid-core thick wire.
2. Get yourself some Panasonic FA or FC 10000uF caps.
3. Next step you should look at the regulator (if any) and coupling caps in the signal path.
Have fun and enjoy.
P.S. Nice pictures BTW. |
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| millwood |
| quote: | Originally posted by SimontY
Thanks for all the advice, it's greatly appreciated. I was intitailly quite upset by ..sa's curt and dismissive remarks, it made me wonder if there was any point in posting here.
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SimontY, don't get upset. This is a place for people to exchange ideas and your post and picture did nothing but that.
While I do agree with analog_sa that the mod did not make a difference sonically, it is the fact that you tried that matters at the end of the day.
and I for one like to see more people trying and I can tell you that I enjoyed your pictures. |
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| analog_sa |
| Of course i can explain the 'dismissive remarks', although there's hardly any need. Adding random types of capacitors to a finely tuned device like the Caspian is taking random shots in the dark with a very inaccurate gun. The Roksan folks have a good reputation for sound at a modest outlay and have definitely listened to dozens of caps before choosing the types which produce the best bang for the buck in that particular design. I would be hesitant to recommend cap replacements with even 'approved'' audiophile types, as even BGs and nice films (Multicaps, Hovlands etc) may change the sound balance in a less than musical way. Is it possible to improve upon a mid range good sounding amp? Certainly, but it will take a good set of ears, carefully auditioning each change, a lot of experience in what really makes for a positive and worthwhile change and a fairly good idea of what you're doing. Oh, and a circuit diagram or good understanding how the circuitry works is certainly beneficial. I would have had a less dismissive attitude if the original poster had at least taken the trouble to take the circuit diagram off the board, including bias currents, use of dc servo etc. Why do we need to see pictures of wire and caps? Is there anything actually being built? I would be more interested to see pics of Simon's pet dog. |
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| SimontY |
I don't have a dog, but I will endeavour to post some pictures of my pet cat for you ;)
Once again, thanks a lot for the help/support/advice.
ps-on the Caspian, IMHO it isn't so good that it can't be improved easily - common sense tells me so much, it's barely ahead of the much cheaper Kandy (more refined, but far less powerful sounding/and on paper). |
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| analog_sa |
| quote: | | but I will endeavour to post some pictures of my pet cat |
Sounds good. I love cats.
| quote: | | I am going to try adding 4x 10,000uf to really beef it up, and we'll see what that does for the bass... |
It will likely turn it into a not very powerful subwoofer amp. Adding capacitance certainly changes the sound and i remember well how in the 80s all the american mags were coming up with monstrous capacitance banks projects; the authors, likely eligible for deaf disability payments, all claimed tremendous improvements in all areas. All areas bellow 100Hz, that is :) Adding capacitance above a sensible limit, in particular to a class AB amp is very likely going to destroy the subjective dynamics, especially microdynamics; dull the timbre and also put excessive strain on both transformer and diodes. It will probably also increase the diodes switching noise. And your cat won't appreciate it.
peter |
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| SimontY |
2 nights ago I added 2x10,000uf 63v Samwha, as I suggested I might. Rectifiers/transistors are ok so far, but I haven't added that much capacitance or played it for a party - in this house?!? ...not happening
I looked for results with a very open mind, and the knowledge that my Caspian "will likely turn it into a not very powerful subwoofer amp" ( analog_sa)
Before 'warming up/system bedding in/caps running in' the amp sounded unfamiliar, different but not necessarily improved or unpleasant. Hints of extra richness came through from the start, accompanied by some apparent loss of clarity in the mid/top-ranges.
Extended listening shows, I believe, a good sound improvement in overall musicality (rock, electronic, dance listened to mostly). Bass is very impressive, as predicted - it's richer, deeper, and less hard, sounds really effortless. And loud is lots of fun - it just gets louder - much better!
The idea that this sort of modding would make no difference made me wonder if people had tried much and actually listened, not starting an argument here - just saying I know what I heard. And the suggestion that adding much more capacitance would make it a low-power sub amp make me chuckle - this is utter nonsense in my case - and it's very powerful!! (with 91db speakers and a healthy sub, in a small room :) ) I reccommend trying cheap caps to rump up the reservoir storage to anyone with a less than mega-buck amp.
Thanks for reading.
-Simon |
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| SimontY |
ooh, almost forgot ;)
He is called Leo, and doesn't give a flying feck about hi-fi... |
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| SimontY |
Hi tbla,
Those rectifiers look like some nice beasts, but they are 'TO-220AC' package. How could I connect them? Or even better, is there an alternative in the normal diode package? (sorry, I don't know what it's called...)
-Simon |
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| analog_sa |
Simon
I am really glad that you like it - there is absolutely no reason why we should share the same sound preferences - we probably don't listen to the same music either and all this is a question of taste. What is certain, though is that your ears function well :)
There should be no prob replacing your diodes with TO 220, you might have to extend the pins slightly.
peter |
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| Luke |
| quote: | Hi tbla,
Those rectifiers look like some nice beasts, but they are 'TO-220AC' package. How could I connect them? Or even better, is there an alternative in the normal diode package? (sorry, I don't know what it's called...)
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Hi Simon,
if your not sure about making bridges out of discrete diodes, try going to http://www.percyaudio.com/ and download his catalog, have a look at his IXYS bridges, they are allready made up for you and only have to replace your existing ones. If you can spare the cash try getting a couple of Nichion KGs and replace all your caps with 2 nice 10000 uF caps. I think cap quality may do more than actual amount (unless your building class A monsters
;) ) This way you have a higher quality cap and about 30% more capacitance.
BTW If you can pull that off, your almost ready to build a gainclone:) |
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| tbla |
hi simon,
the biggest problem is actually stripping the hole amp apart once more......but you'll get used to it ;)
you could cut the original diodes legs and solder the new ones on to them.....BE CAREFULL its high voltage - so do it proberly...!
go for it !!! |
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| SimontY |
Thanks Peter,
Glad you're happy now, I am too ;)
I actually ordered four of those large caps, but decided to try two first, I won't bother with the other two as I'm quite happy with the result... still plenty of other ways to improve/tailor my sound I'm sure!
re: the diodes, which I am now quite interested in:
Farnell sell axial/DO-204AR Schottky types up to 9A@45v at 2.45ukp each - seems pricey, but if they're really good then 10 pounds or so will be good price for the upgrade, for the four.
Alternatively there are Schottky diodes as DO-220 which look nice, and can take more current. Or there is 15A T0-220AC for £1.79 - this one is 'ultra fast recovery'. Another option could be 'soft-recovery'/do-220/15A/400v.
Can anyone tell me which sort is most appropriate for upgrading an amp psu? Farnell have so much to choose from!
Cheers :)
-Simon |
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| SimontY |
Aha! More options and things to try, thanks chaps. I'd actually started writing that last reply several hours ago and left the room/house, so I'd not seen the previous 2 posts.
Percy audio sell some amazing stuff! Good to look at, though I don't like to order things from the States. Mind you, if I can think of enough things I can't get hold of here... I see what he says about the 'soft recovery' diodes - just what most amps need, I'm sure. I take it the t0-220 or silimar type packages are the ones commonly used for the serious diodes then...
"the biggest problem is actually stripping the whole amp apart once more" - dam right, it's a royal pain in the buttocks. I'm totally used to it with my cd player though - done it so many times to tweak/change things, but I've only just worked up the courage to fiddle with my amp, as it's so much more expensive!
-Simon |
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| analog_sa |
Dunno about the diodes you mention. They may well be good. If you'd rather play it safe i suggest the MUR860 which seem to be generally liked. I get them dirt cheap even in SA - about 50p.
cheers
peter |
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| millwood |
| quote: | Originally posted by analog_sa
If you'd rather play it safe i suggest the MUR860 which seem to be generally liked. I get them dirt cheap even in SA - about 50p. |
but do they sound good tho.? :) |
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| tbla |
| it's one or the other.....go...!:bfold: |
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| SimontY |
MUR860 is 85 pence from Farnell, so about a dollar/euro or more with tax.
Looking at the datasheet, I see MUR820/40/60 are "designed for use in switched mode psus..." Is there significance in this design goal?
Also, what does 'soft-recovery' mean? Are they lower noise? MUR860 doesn't appear to be 'soft-recovery'.
Cheers,
-Simon |
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| SimontY |
Hmm, here is an interesting question for you all.
Has anyone tried bypassing diodes with film caps e.g. 22nf or 220nf, (which I have some of)?
Is this safe, and is it worthwhile? If so, I will try this before replacing the diodes, and see if there is any noticable difference to sound-q. I would position the caps across the tops of the diodes, the legs would just reach each of the diodes' legs.
Any thoughts?
-Simon |
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| SimontY |
Thanks tbla, I searched Farnell for that part no. and found it, it's £3.06 - pricey, so I hope they're good ;) I will order them soon I reckon...
Meanwhile I've shielded some caps and a chip in the amp - yeh, I know it shouldn't make much difference, but I like to do these things :) (worked in my cd player, I think)
Tbla, you seem to know the Caspian well :) I saw some caps, Wima I think, near the diodes and wondered if these were 'bypass' - I wouldn't know without turfing the board out!
Will keep y'all posted....
-Simon |
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| SimontY |
Oh my word, they're one quarter the price!!!
Have you ever heard the phrase 'rip-off Britain'...? This is a perfect example. And I believe one needs a trade account to buy goods from RS here :( Oh well, it's only 4 I need, so it's not a huge amount in total.
BTW there are three voltage regulators with large heatsinks on them, are these likely to be critical? I think two are in the pre-amp section, so I guess they are very important. The sinks get incredibly got, even with the outer cover off - is it wise to apply some good thermal paste inbetween the reg. and sink? Or even to fix on a larger heatsink? I remember reading how they work better at lower temps... though my amp sounds better as it gets hotter - as they all (class a/b) seem to.
-Simon |
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| tbla |
yes, its a rip off - but schuro has some very good prices too.....
and you only need 4 of them so perhaps farnell is the way to go.
if you want to do anything else to your amp, i strongly advice you to get a service manual and study it closely..... |
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| trwh |
Simon,
| quote: | | Have you ever heard the phrase 'rip-off Britain'...? This is a perfect example. And I believe one needs a trade account to buy goods from RS here Oh well, it's only 4 I need, so it's not a huge amount in total. |
Anyone can order goods from RS - via their website at www.rswww.com.
See ya,
Tim.
BTW - for reasonably priced no nonsense components in the UK, Rapid Electronics, at www.rapidelectronics.co.uk, are easily the most competitive. |
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| trwh |
Also Simon,
Just to say that I liked seeing your pics - I always enjoy seeing inside electronic equipment. However, my gut reaction was similar to analog's, I am afraid that products such as these will not benefit from, as someone put it, crude "shots in the dark". Nevertheless, you seem to be enjoying yourself, so who am I to stop you? Just be sure not to damage the product, for instance I would be cautious of adding more reservoir capacitance.
See ya,
Tim.
PS - How much did the unit cost? |
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| SimontY |
Thanks Tim, rapidelectonics looks promising.
The Caspian integrated is £900 new, but mine was 2nd hand.
About the shots in the dark - the amp, and my hi-fi as a whole has never been brilliant musically, or even in some certain basic hi-fi terms/areas. Modding has usually worked on other components - cd players, speakers, well the last two pairs were home made or kit.
When I mod. I can tailor the sound to my personal preferences, and I have just about enough knowledge to get away with it, or have done so far. And that brings me to another point, this is a learning experience, and hands-on is the way I learn best. I really don't care for the opinion that "the manufacturer knows what he is doing, leave it alone". It doesn't hold weight for several reasons: Firstly, things like my amp are designed, then built down to a cost, and made easy to manufacture/repair etc. and are made to be reliable. Performance is certainly high on the list of priorities, but when so little is actually spent on the components, 15% maybe(??), even on a £900 amp this is quite little, one can expect to be able to improve performance with some fairly careful tweaking.
Furthermore I believe most products, like my Caspian, are designed to produce a sound that will sell itself, get a good review, or be easy to listen to, or if possible all of these, though that is a contradiction as I see it.
In large chains such as Richer Sounds and Sevenoaks, *the* large chains in the UK, the products people tend to buy are the ones that have been well-reviewed by What Hi-Fi, and sometimes the other mags. This fact alone puts pressure on middle-market manufacturers such as Roksan to knock out units which will sound impressive if not good, on a first listen, and not necessarily be satisfying longer term.
My number one complaint for over two years now has been harshness in equipment, and that typical mushiness, but that's just being picky. Without guided and shot-in-the-dark modifications, my hi-fi would be seriously unlistenable. I honestly cannot say for sure why my old amp (Roksan Kandy) sounded so much more harsh than the current one, the Caspian. What I can say for sure though, is I know what I like, and I'll take whatever measures are necessary to achieve my goals - and bear in mind I'm poor so I can't just buy the ideal solutions :)
I am actually at a fairly happy point now - I can listen at high volumes without feeling dizzy and having my ears close up, I can hear details reminiscent of live music, and have a relatively deep, rich, solid, and punchy bass...
However, I could really do with better midrange presence (that might be what I'm after), even less harsness/glare/brightness/whiteness and more solidity in the bass.
I really felt the need to explain myself at this point, I hope you don't take it the wrong way :)
-Simon
ps. I've just taken on part time work in a hi-fi shop, so I can compare and see if my 'souped up' system really is better £ for £ than original stuff... so far it's promising ;) |
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| trwh |
| quote: | | I really felt the need to explain myself at this point, I hope you don't take it the wrong way |
Not at all! Having read your reply, I respect your viewpoint. You must understand that I am currently tending to look at audio from an increasingly objective viewpoint. This is down to my uni course, and my live sound work.
Anyway, good luck with your HI-FI, and do try Rapid at some stage.
See ya,
Tim. |
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| SimontY |
Tim, I can certainly understand your angle too. I wish I had the mathematical nouse to be able to deal with an EE course. Maybe one day I'll try, it would certainly help with the hobby :)
tbla, I recently replaced 6 or 7 diodes (according to tnt audio's cd63 modding pages) with Schottky types. At the same time I added a .33uf mains cap. Combined this was a stunning improvement - finally I can hear truly sweet treble through my speakers - but only if it's on the disc in the 1st place! Also, .33uf is a surprisingly potent amount for discharging into ones wrist :bigeyes:
-I'll not be making that mistake again!
re. opamps, I bought some new ones a while back: analog devices ad825, but they are 1/2 the correct size, doh!!
I've since decided to leave them alone for now, though with all the mods I've done, it's probably about time, though I guess I'll also need to buy a solder pump for this one!
How can I be sure of buying the right package opamp? When I made my mistake I looked at the datasheet and saw a familiar 8-pin thing, so took it as safe...
-Simon |
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| SimontY |
| Haha, this'll make you smirk... |
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| SimontY |
And the top, where 2 were replaced. They are too large :rolleyes:
Large improvement to smoothness/listenability though, very happy with it. And I still have trouble believing it works, after half destroying two areas of the pcb!! |
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| tbla |
| how'sitgoin'....?:xfingers: |
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| SimontY |
Not had much time last few days, I've not ordered anything or done anything, apart from a small cd player mod. Replaced the output caps for some tiny film ones, and it was a sonic disaster, so they will be changed back, maybe tonight.
http://www.diyaudio.com/forums/show...&threadid=18172
btw I don't know where to buy that opamp from, and is it definately a 'drop-in' replacement for my current ones?
-Simon |
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| SimontY |
Hi tbla, this may or may not be of interest:
I removed those film caps from the output of my cd player, and completed the circuit with silver wire, which I had spare.
A veil was removed, but I need to listen more to appreciate fully what has happened.
Also, I notice the last thing in the signal path here is a 200ohm resistor, which on one channel measures 198ohms and on the other measures 200ohms. Is this discrepency enough to upset the left-right balance? Is it worth changing these for high quality, tight tolerance resistors?
Cheers,
-Simon
ps. maybe I should start a new thread just to beg for help with my cd player :goodbad: |
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