JRC makes clones eg. the RC4558 is a TI chip but JRC makes some the VCAs are Mitsubishi, but JRC makes some too, send them an e-mail, they can send you infos about obsolete components, but you might receive it after a couple of months. Note: I saw they rebuilt the site, maybe the support has changed. It's NJR.COM (NewJapaneseRadio's logo is JRC) "nelsonj_sce" <nelsonj_sce@...> wrote: > >Hack update: >Since my last note I replaced the other two op-amps with socketed Burr >Brown OPA4228. Replacing these two other op-amps did reduce noise >levels noticeably. There is still some noise but with 1)the these >four super clean op-amps, 2)using Multi, 3)routing everything to a >sinlge output on the multi rather than mix, and 4)using my noise gate, >noise is really not an issue any more. I would love to try and >replace the VCAs also, but I have not been able to track down a spec >sheet (or any other info on the) on them so I do not have a clue as >what might works as an upgraded part. > >If anyone can help, the VCAs are part M5222L and they are from >the same off-brand Japanese JRC company that is used elsewhere in the >K5. If anyone can help me with details on the M5222Ls I will see if I >can find a replacement parts. > >My bottom line: If you are willing to lay-out $30 for the four BB >OPA4228 and sockets, and you if you are willing to remove some >tough-to-remove parts, I highly recommend this op-amp replacement >hack. My K5 has much less noise and just sounds much warmer/classier >with the new parts. I would love remove more noise, but right now it >sounds very good and I am not very motivate to continue hacking. (I >do still plan on replacing the headphone circuit though since I >already made the new circuit and all I have to do is wire it up.) > >An interesting aside: After I did the latest op-amp replacement, >everything sounded great in multi, but when I went to single I had >serious problems. Various ranges of the keyboard worked fine, while >other ranges sounds like a fried amp circuit. It turns out that while >I was removing IC8 I accidentally pulled part of the circuit board >trace off that connected pins 1 and 2 on IC8. This trace provides the >feedback loop between the (-) and output of line G2. Once I tracked >down the problem I was able to reconnect pins 1 and 2 and then >everything in single mode worked great. What I conclude from this is >that the K5 in single mode is splitting different ranges of the >keyboard to different op-amps. I am not sure what K% is doing in >multi but multi (ouput 1) DOES NOT use the opamp in IC8 pins 1-2-3. > >Hack on. > > >--- In k5synth@yahoogroups.com, "antdes45dragonmaster" <antdes45@n...> >wrote: >> >> Not exampe, example >> >> --- In k5synth@yahoogroups.com, Antoine Desch\ufffdnes ><antdes45@n...> wrote: >> > Removing the opamps one by one could help: >> > exampe. You remove the 2nd last opamp and there is no more noise, >then >> > noise source is not at final stage. >> > >> > nelsonj_sce@y... a \ufffdcrit: >> > >> > > >> > > Per one of my earlier notes, I took out my BB opamp part U4 and >> > > replaced it with a rewired Tl074 where I lifted the ground pins >3, 5, >> > > 10, 12 and rewired them to a different ground. Bottom line: >Using a >> > > different ground for U4 made very little improvement in noise. >It did >> > > reduce it a bit, but the noise reduction is not worth the >effort. I >> > > even tried 4 different new ground locations,including the main >ground >> > > by the xmfr, but none of the grounds resulted in any meaningful >noise >> > > reduction. >> > > >> > > Anyway, this hack is not worth doing. Back to the drawing >board... >> > > >> > > --- In k5synth@yahoogroups.com, Antoine Desch\ufffdnes ><antdes45@n...> >> > > wrote: >> > > > Good opamps might not change the noise amout that much. But I >know >> > > wiaht >> > > > 2 opamps in parallel are doing with noise is like what 2 >resistors >> > > in >> > > > parallel are doing: reduce it(noise in the case of opamps if >it's >> > > not >> > > > series, I've read this somewhere) >> > > > >> > > > antdes45@n... a \ufffdcrit: >> > > > >> > > > > Well, in my case, the mixer is pretty niosy too(A Kawai MX8R >> > > mixer >> > > > > from the same year), and I've never found Multi louder than >Single >> > > nor >> > > > > Singles louder than Multi, nor that Mix is more noisy than >> > > > > Singles(Tried with VU meter too, maybe it's the same for you >since >> > > you >> > > > > changed your opamps, but maybe you haven't changed the 4 >opamps >> > > as I >> > > > > did). I've already plugged the K5 directly in the SBLive >line >> > > in(Which >> > > > > is -90dB), but obtained a -46dB at the volume I get a -90dB >> > > without >> > > > > source on the SoundForge VU Meter. >> > > > > >> > > > > It's pretty noisy I know it, idtheory.com has a 6MB MP3 made >with >> > > 2 >> > > > > K5s in 1991. >> > > > > >> > > > > nelsonj_sce@y... a \ufffdcrit: >> > > > > >> > > > >> >> > > > >> You wrote: "I only use MIX output and headphones" >> > > > >> I don't use the MIX now, rather, I stack everything in a >Multi >> > > to a >> > > > >> single output , Out 1 usually. It makes the sound cleaner >> > > because you >> > > > >> skip one of the op-amps. You might want to try this trick >to >> > > help >> > > > >> clean up the sound. >> > > > >> >> > > > >> --- In k5synth@yahoogroups.com, Antoine Desch\ufffdnes >> > > <antdes45@n...> >> > > wrote: >> > > > >> > You told a couple of replies before "I suppose you now >have >> > > socketed >> > > > >> > opamps, like me", well I don't have some, I forgot to ask >them >> > > at >> > > > >> the shop. >> > > > >> > >> > > > >> > "U1 if you use MIX" >> > > > >> > I only use MIX output and headphones. I don't have >time/want to >> > > build >> > > > >> > some 4 \ufffd m wires. And my mixer is 8 channels : 2 for >the >> > > first >> > > Roland >> > > > >> > D110, 2 for the second one, and 1 for the K5, if I would >do >> > > that, I >> > > > >> > would lose all the 3 other inputs, which I use sometimes. >> > > Also, I >> > > > >> don't >> > > > >> > use the K5 for recording or anything else, I modifiy it >even >> > > if I'm >> > > > >> just >> > > > >> > playing it when I've got nothing to do. The K5 is just a >kind >> > > of toy >> > > > >> for >> > > > >> > me(And my father owns it, and uses it rarely to use it >as a >> > > controller >> > > > >> > in Finale). >> > > > >> > >> > > > >> > nelsonj_sce@y... a \ufffdcrit: >> > > > >> > >> > > > >> > > >> > > > >> > > You wrote: "They connected the non-inverting(+) >input(if I'm >> > > > >> right) to >> > > > >> > > the DG?!?" >> > > > >> > > Not directly. The schem show that the (+) is >connected to >> > > the >> > > > >> AG, but >> > > > >> > > it appears from the wiring board layouts that the AG >and DG >> > > have >> > > > >> > > ground planes that connect in several places. So >basically, >> > > there is >> > > > >> > > no physical seperation of the AG and DG ground planes >on >> > > board >> > > > >> MI-004. >> > > > >> > > As a result the (+) is connected to this single ground >plane >> > > that has >> > > > >> > > both A and D parts on it. >> > > > >> > > >> > > > >> > > >> > > > >> > > You wrote: "What's the VCA's ground?" >> > > > >> > > The same dirty AG/DG ground as that of U4. The VCAs >are >> > > parts >> > > > >> IC6 and >> > > > >> > > IC7. The ground is pin 3, there is also a ground >through a >> > > cap on on >> > > > >> > > pin 5 but this look like protection rather than ground. > I am >> > > not >> > > > >> sure >> > > > >> > > if pin 3 is the third pin from the top or from the >bottom, >> > > but pin 4 >> > > > >> > > is -A6. It can't hurt to move the VCA's grounds to a >clean >> > > ground >> > > > >> > > also. Note that it looks to me that the VCA's do not >play >> > > the >> > > > >> role of >> > > > >> > > traditional synth VCAs, but rather the are connected >directly >> > > to the >> > > > >> > > main volume slider via pin 5. They don't seem to have >any >> > > other >> > > > >> > > control voltages so my guess is that all the VCAs do is >> > > control the >> > > > >> > > overall volume of the keyboard. If that is the case, >I am >> > > note sure >> > > > >> > > that a dirty ground will inject noise. But again, it >can't >> > > hurt to >> > > > >> > > make sure they have a clean ground. >> > > > >> > > >> > > > >> > > So here is my plan: Step 1 is change the ground on U4 >(and U1 >> > > if you >> > > > >> > > want to use the Mix output). Step 2 is change the >ground on >> > > the >> > > > >> VCAs. >> > > > >> > > Parts U8 and U9 are set up as non-inverting amps and >do not >> > > have any >> > > > >> > > direct connections to ground so no grounding to change >here, >> > > but they >> > > > >> > > have that shielding that we may be able to improve as >Step 3. >> > > > >> > > >> > > > >> > > I may be able to do step 1 tonight - it all depends on >how >> > > sleepy my >> > > > >> > > baby is! >> > > > >> > > >> > > > >> > > >> > > > >> > > --- In k5synth@yahoogroups.com, antdes45@n... wrote: >> > > > >> > > > Pulling the DG from the boards not PSU >board(Impossible, >> > > without >> > > > >> > > removing a bridge rectifier), I've already used the PSU >> > > without the >> > > > >> > > big brown connector full of wires for power and ground >of the >> > > boards. >> > > > >> > > > >> > > > >> > > > They connected the non-inverting(+) input(if I'm >right) to >> > > the >> > > > >> DG?!? >> > > > >> > > > Well, sure it will make noise, if that ground is that >much >> > > noisy, >> > > > >> > > that would be like to plug a phono playing in the >input and >> > > wondering >> > > > >> > > why you hear it.(Well, that's what I think) >> > > > >> > > > >> > > > >> > > > What's the VCA's ground? >> > > > >> > > > >> > > > >> > > > Also, they put two mono DACs for 4 channels, so (My >> > > theory) the >> > > > >> > > analog sound is passing thru a kind of flip-flop that >> > > switches >> > > > >> rapidly >> > > > >> > > the input from 1 to 2 to 1 ... and the other with 3 and >4. As >> > > I only >> > > > >> > > have a part of the output board, the opamp section and >the >> > > > >> PSU(Thanks, >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > "nelsonj_sce" <nelsonj_sce@y...> wrote: >> > > > >> > > > >> > > > >> > > > > >> > > > >> > > > >Antdes, >> > > > >> > > > >Ok, I still have more work to do but I did look >more at >> > > the schems >> > > > >> > > > >while on a plane today. Some thoughts... >> > > > >> > > > >1) DO NOT simply remove the DG ground on the power >supply >> > > and >> > > > >> reroute >> > > > >> > > > >it to the AG (black transformer wire). If you do >this >> > > the >> > > > >> inverter >> > > > >> > > > >for the backlight (as well as several caps and part >D6 >> > > WILL NOT BE >> > > > >> > > > >GROUNDED. Basically the DG does not terminate on >MI-010, >> > > rather >> > > > >> > > > >MI-010 needs the connection <CN1> in order to be >> > > grounded. I >> > > > >> am still >> > > > >> > > > >looking at things but it seems the main ground for >the >> > > MI-003 >> > > > >> &MI-004 >> > > > >> > > > >comes from where they are screwed in to the K5 case. >> > > > >> > > > > >> > > > >> > > > >2) Although I am not 100% sure, it appears that for >some >> > > > >> reason, on >> > > > >> > > > >board MI-004 the DG and AG are actually connected. >Board >> > > > >> MI-003 is >> > > > >> > > > >all digital so the ground is pure digital. If I am >> > > correct, >> > > > >> and the >> > > > >> > > > >AG and DG grounds are not separated on MI-004, this >may >> > > be the >> > > > >> source >> > > > >> > > > >of the noisy ground. The bad news is that there is >no >> > > quick >> > > > >> way to >> > > > >> > > > >separate the grounds on MI-004. >> > > > >> > > > > >> > > > >> > > > >3) Part U4 (the op-amp right after the VCA that we >have >> > > both >> > > > >> replaced) >> > > > >> > > > >has my attention. It has four inverting op-amps, >where >> > > the "+" of >> > > > >> > > > >each amp is connected directly to the dirty ground. > It >> > > is >> > > > >> possible >> > > > >> > > > >that the dirty ground is basically injection noise >to >> > > these amp. >> > > > >> > > > > >> > > > >> > > > >I think we both have replaced this op-amp and it is >now >> > > in a >> > > > >> socket. I >> > > > >> > > > >plan on taking out the amp(this is a total hack but >if it >> > > works >> > > > >> I can >> > > > >> > > > >make it look nice later), and then bending >connections 3, >> > > 5, >> > > > >> 10, 12 >> > > > >> > > > >(the grounds) out so that they do not connect to the >> > > socket/dirty >> > > > >> > > > >ground on board MI-004. Then, I will wire these >> > > connections >> > > > >> directly >> > > > >> > > > >to the K5's case to try and get a clean ground. >> > > > >> > > > > >> > > > >> > > > >4) If that does not help lower the noise, I am >looking at >> > > lines >> > > > >> g0-g7 >> > > > >> > > > >that feed the op-amps U8 and U9. These are the only >> > > analog signal >> > > > >> > > > >lines that have Faraday shielding. These are low >level >> > > lines >> > > > >> early in >> > > > >> > > > >the analog signal chain. If nosie gets in to these >> > > lines, the >> > > > >> nosie >> > > > >> > > > >will get amplified in each of the following amp >stages. >> > > > >> Perhaps there >> > > > >> > > > >is a way to improve the shielding on these lines or >to >> > > change the >> > > > >> > > > >grounds related to these singal paths...but I have >to >> > > think >> > > > >> about how >> > > > >> > > > >to do it. >> > > > >> > > > > >> > > > >> > > > >Anyway, I will let you know what happens after I >reground >> > > U4. >> > > > >> > > > > >> > > > >> > > > > >> > > > >> > > > > >> > > > >> > > > > >> > > > >> > > > >--- In k5synth@yahoogroups.com, antdes45@n... wrote: >> > > > >> > > > >> That's it, AG is analog ground, DG digital ground, >+A6V >> > > dc >> > > > >> analog >> > > > >> > > > >6v. . . >> > > > >> > > > >> The kind of fork for the analog ground is an other >sign >> > > for >> > > > >> ground, >> > > > >> > > > >maybe they mean different connection places, as the >fork >> > > like >> > > > >> is used >> > > > >> > > > >for antenna too. But I think it's just a >country/continent >> > > > >> difference. >> > > > >> > > > >> >> > > > >> > > > >> "nelsonj_sce" <nelsonj_sce@y...> wrote: >> > > > >> > > > >> >> > > > >> > > > . . . Cut the file, was 62k. >> > > > >> > > > >> > > > >> > > > -- >> > > > >> > > > Antoine Desch\ufffdnes >> > > > >> > > > aka DragonMaster >> > > > >> > > > http://thehotcom.deep-ice.com/ >> > > > >> > > > Files:http://angelfire.com/ca7/hotcomcenter/ >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > ____________________________________________ >______________________ >> > > > >> > > > Switch to Netscape Internet Service. >> > > > >> > > > As low as $9.95 a month -- Sign up today at >> > > > >> > > http://isp.netscape.com/register >> > > > >> > > > >> > > > >> > > > Netscape. Just the Net You Need. >> > > > >> > > > >> > > > >> > > > New! 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Groups Links >> > > > >> > > >> > > > >> > > * To visit your group on the web, go to: >> > > > >> > > http://groups.yahoo.com/group/k5synth/ >> > > > >> > > >> > > > >> > > * To unsubscribe from this group, send an email to: >> > > > >> > > k5synth-unsubscribe@yahoogroups.com >> > > > >> > > >> > > > >> ><mailto:k5synth-unsubscribe@yahoogroups.com?subject=Unsubscribe> >> > > > >> > > >> > > > >> > > * Your use of Yahoo! Groups is subject to the >Yahoo! >> > > Terms of >> > > > >> > > Service <http://docs.yahoo.com/info/terms/>. >> > > > >> > > >> > > > >> > > >> > > > >> > >> > > > >> > -- >> > > > >> > antdes45@n... >> > > > >> >> > > > >> >> > > > >> >> > > > >> >> > > > > >> > > > > -- >> > > > > antdes45@n... >> > > > > >> > > > > Yahoo! Groups Sponsor >> > > > > ADVERTISEMENT >> > > > > >> > > <http://us.ard.yahoo.com/SIG=129d83doj/M=315388.54 >> > > 97957.6576270.3001176/D=grplch/S=1705032144:HM/EXP >> > > =1098058092/A=2372354/R=0/SIG=12id813k2/*https://w >> > > ww.orchardbank.com/hcs/hcsapplication?pf=PLApply&m >> > > edia=EMYHNL40F21004SS> >> > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > -------------------------------------------------- >> > > ---------------------- >> > > > > Yahoo! Groups Links >> > > > > >> > > > > * To visit your group on the web, go to: >> > > > > http://groups.yahoo.com/group/k5synth/ >> > > > > >> > > > > * To unsubscribe from this group, send an email to: >> > > > > k5synth-unsubscribe@yahoogroups.com >> > > > > <mailto:k5synth-unsubscribe@yahoogroups. >> > > com?subject=Unsubscribe> >> > > > > >> > > > > * Your use of Yahoo! Groups is subject to the Yahoo! >Terms of >> > > > > Service <http://docs.yahoo.com/info/terms/>. >> > > > > >> > > > > >> > > > >> > > > -- >> > > > antdes45@n... >> > > >> > > >> > > >> > > >> > > Yahoo! Groups Sponsor >> > > ADVERTISEMENT >> > > >> ><http://us.ard.yahoo.com/SIG=129m2cs7f/M=315388.55 >00238.6578046.3001176/D=grplch/S=1705032144:HM/EXP >=1098142001/A=2372354/R=0/SIG=12id813k2/*https://w >ww.orchardbank.com/hcs/hcsapplication?pf=PLApply&m >edia=EMYHNL40F21004SS> >> >> > > >> > > >> > > >> > > >> ------------------------------------------------ >------------------------ >> > > Yahoo! Groups Links >> > > >> > > * To visit your group on the web, go to: >> > > http://groups.yahoo.com/group/k5synth/ >> > > >> > > * To unsubscribe from this group, send an email to: >> > > k5synth-unsubscribe@yahoogroups.com >> > > ><mailto:k5synth-unsubscribe@yahoogroups.com?subject=Unsubscribe> >> > > >> > > * Your use of Yahoo! Groups is subject to the Yahoo! Terms >of >> > > Service <http://docs.yahoo.com/info/terms/>. >> > > >> > > >> > >> > -- >> > antdes45@n... > > > > -- Antoine Desch\ufffdnes aka DragonMaster http://thehotcom.deep-ice.com/ Files:http://angelfire.com/ca7/hotcomcenter/ __________________________________________________________________ Switch to Netscape Internet Service. As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register Netscape. Just the Net You Need. New! Netscape Toolbar for Internet Explorer Search from anywhere on the Web and block those annoying pop-ups. Download now at http://channels.netscape.com/ns/search/install.jsp
Message
RE: [k5synth] Re: Notes on Schems...update on grounding experiment
2004-10-24 by antdes45@netscape.net