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Post by joey808 on Sept 12, 2014 9:01:09 GMT -6
Been looking around, does anyone here know how to do it? I know zen pro audio does them, can't afford to send them out. Any help would be appreciated.
Thanks.
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Post by jimwilliams on Sept 12, 2014 9:21:08 GMT -6
They use BB OPA2134 opamps, long in the tooth and not the best part for a transparent monitor. I would try National LME49720's. Add .1 uf psu bypass caps from the power rails to ground. Replace the film crossover caps with Wima MKP-2 or FKP-2. Replace the el coupling caps with Panasonic FR series, enlarge the values, doubling gets an additional octave extension in the low end. Bypass with a quality poly film cap like Wima.
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Post by svart on Sept 12, 2014 9:31:11 GMT -6
Heh, I remember when Jim was all about those OPA2134..
Seems like the greatest difference people are reporting is removing the "limiter" circuit. I don't see any instructions on this though. If you can find schematics, we can find it and instruct you on removing it.
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Post by joey808 on Sept 12, 2014 14:56:38 GMT -6
Thanks Guys! I Appreciate it, Schematics and instruction would be awesome!
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Post by jeromemason on Sept 14, 2014 22:36:30 GMT -6
Hey joey808Here's the Schematic for the Hs80m, I don't know if it will help but I believe they are similar. www.dropbox.com/s/g3865cyvf463thr/HS80M_HS50M_Schematics.pdf?dl=0I did the mod on my HS80's sans the opamps. I would say just clipping the limiter jumper will amaze you. Even at low volumes the limiter is working, and when you clip it all of a sudden they seem much more like NS10's in regards to transient response. And, I've had them very loud…. they aren't going to blow, just treat them as you would a pair of passive speakers and all will be find. I used Wima where the mylar caps are in the signal path, also a few that go to group with Wima's. I replaced all the electrolytics with Elna Similic II with a value of 22uf in the 10uf locations. I used the same values for the rest of the electrolytics with the better Elna's. It did take a way a lot of harshness and the lowend felt better as well. I would love to replace the Opamps, I've got the Op2134's to replace the 4558's with, but the PCB is extremely sensitive to heat, you'll peel a trace quick if you don't watch what you're doing and take your time, and that's just on the caps replacement. jimwilliams do you know of a good way to get those SMD 4558's off? |
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Post by svart on Sept 14, 2014 22:54:01 GMT -6
Best way is a hot air solder station.
You can use two irons if you are coordinated, just put big solder blobs across each row of 4 pins and place the irons in those blobs until the chip moves.
A good solder tech can get them off with a little solder and a hot iron, though.
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Post by joey808 on Sept 15, 2014 0:24:20 GMT -6
Thanks Jerome!
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Post by jimwilliams on Sept 15, 2014 10:17:58 GMT -6
www.chipquik.comTry this stuff. It's a super low temp lead based solder that you spread across the pins after soaking it in the low temp flux that comes with it. Then it lifts off quickly at a lower temerature than regular solder will melt. Using a hot air station risks melting the solder on nearby tiny SM passive parts that will tend to swim away...
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Post by svart on Sept 15, 2014 11:47:38 GMT -6
www.chipquik.comTry this stuff. It's a super low temp lead based solder that you spread across the pins after soaking it in the low temp flux that comes with it. Then it lifts off quickly at a lower temerature than regular solder will melt. Using a hot air station risks melting the solder on nearby tiny SM passive parts that will tend to swim away... Only if the station's air flow rate is too high.. |
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Post by jimwilliams on Sept 15, 2014 12:41:18 GMT -6
Or if the density is too high. Tiny SO8 chips next to a bunch of 0808 passives is going to be a b*tch as the air flow is almost impossible to focus that tight. It does work well on larger chips like dsp and processors.
Another alternative is to use a very fine tipped shear and cut the leads off next to the die. Then a Hakko 808 tool with the larger nozzle will suck it all up leaving a clean pad. That requires a light touch and skills.
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Post by svart on Sept 15, 2014 12:46:56 GMT -6
You have to watch out for copper less than 1oz in cases of clipping leads like that. The shearing force will push the lead upwards and if the copper isn't thick enough and with enough width to keep it bonded to the PCB, then the pad and everything will pop up off the fiberglass.
I may or may not have been guilty of doing exactly that many times over the years.
I've blown off my share of parts with hot air too, but on low profile parts like resistors, it's not as big of a deal as a high profile capacitor or inductor. Usually if the solder pad is large enough, the bonding strength of the solder's surface tension will still hold it in place.
Personally I just run a bead of solder along both sides of the part with a lot of heat and speed and lift it away with tweezers. But then again I have 20 years experience doing SMD work too..
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Post by Deleted on Sept 15, 2014 16:52:42 GMT -6
Another tricky method is to cut the legs of the ICs with a Dremel tool.
Has to be done with extreme care and control to not accidentally damage the PCB, cut the legs as near as possible to the package, then, if the package is not glued to the PCB, it drops off, no heat involved yet.
If this succeeds, you can desolder each leg rest independently, which is muuch easier...
Another method is to put a strand thru underneath the IC package, solder and heat one side first and pull the strand in this side's direction.
The strand will lift the legs of this side off the pcb. Then you can desolder the other side much easier.
Both techniques will shorten the critical heating times significantly and help to avoid board damage.
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Post by jeromemason on Sept 15, 2014 23:47:52 GMT -6
Ugh you guys are making me want to put my Opa2134's in now lol….. I had to buy an input board that was like $150 because I attempted this and broke a few traces. The input board is extremely sensitive on this speaker, it's really easy put pull a pad or break a wire.
The way I tried it was I used a desolder wick and quickly pull the solder from the IC pads, Then i cut the legs from the IC and one foot at a time heated it and lifted them off. Did pretty good and got confident and then, boom pad came up with one of the feet and I couldn't fix the board. So I just elected to clip the limiter and swap the electrolytics and I've been happy with them, but from folks I've talked to, swapping those op amps makes an amazing difference in the sound. I might just send them to someone that can do it for me if they don't charge me an arm and a leg.
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Post by svart on Sept 16, 2014 6:42:21 GMT -6
Ugh you guys are making me want to put my Opa2134's in now lol….. I had to buy an input board that was like $150 because I attempted this and broke a few traces. The input board is extremely sensitive on this speaker, it's really easy put pull a pad or break a wire. The way I tried it was I used a desolder wick and quickly pull the solder from the IC pads, Then i cut the legs from the IC and one foot at a time heated it and lifted them off. Did pretty good and got confident and then, boom pad came up with one of the feet and I couldn't fix the board. So I just elected to clip the limiter and swap the electrolytics and I've been happy with them, but from folks I've talked to, swapping those op amps makes an amazing difference in the sound. I might just send them to someone that can do it for me if they don't charge me an arm and a leg. That's pretty much what I was talking about. Never ever clip the leads on SMD packages (unless you know what you are doing, and even then it'll probably end badly..).. |
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Post by Deleted on Sept 16, 2014 8:03:54 GMT -6
Yupp, clipping legs of SMD package with pliers is a lot of mechanical stress on the pad...
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Post by Warhead on Sept 29, 2014 21:11:47 GMT -6
We tried several models of op-amps before choosing the 2134 by the way, as it sounded the most natural within this design.
Fits like a glove in our experience, and far detailed enough for excellent transient response and opens them right up.
Others tended to sound more metallic or had a sheen to them.
Who cares if something specs out higher, but sounds bad within a particular design?
The speaker is far more limited physically than most op-amps are electronically.
I'm not a technical guy, I use my ears.
We both agreed on the 2134, and marched on with it.
Feel free to experiment if you can do this on your own, but be aware all that work on those delicate parts and traces will probably earn you a ruined speaker or two.
We use Panasonic FR series and WIMA caps as replacements as well.
War
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Post by jeromemason on Sept 30, 2014 2:33:32 GMT -6
We tried several models of op-amps before choosing the 2134 by the way, as it sounded the most natural within this design. Fits like a glove in our experience, and far detailed enough for excellent transient response and opens them right up. Others tended to sound more metallic or had a sheen to them. Who cares if something specs out higher, but sounds bad within a particular design? The speaker is far more limited physically than most op-amps are electronically. I'm not a technical guy, I use my ears. We both agreed on the 2134, and marched on with it. Feel free to experiment if you can do this on your own, but be aware all that work on those delicate parts and traces will probably earn you a ruined speaker or two. We use Panasonic FR series and WIMA caps as replacements as well. War Still gotta send my input cards to you to have those 2134's put in. Shoot me an email soon to let me know what that's going to run me if you don't mind. BTW Warren and his guy definitely cracked the code of the HS8/HS80m's, I was fortunate enough to work out a deal with him, so he helped me with the caps selection and opamps. Just cutting the limiter, replacing the caps is a huge improvement, and from what Warren is saying the 2134 goes above that even more, I want to get that done ASAP. Hit me up as soon as you can buddy. |
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Post by francolargo on May 19, 2015 20:04:48 GMT -6
Been looking around, does anyone here know how to do it? I know zen pro audio does them, can't afford to send them out. Any help would be appreciated. Thanks. I just happened across this thread... I'm a DIYer testing a new Linux-based bit perfect music player and high end DAC. My whole 'big system' is down for upgrades. So I'm using my monitors for testing - either Mackie MR5s or the Yamaha HS8s. I was surprised to hear the 5" Mackies 'out-punch' the 8" Yamahas and researched the cause, which brought me here. Long story short - I disabled the Yamaha limiter circuit and it significantly improved the performance. ...heard especially on vocals, jazz bass, etc. For my uses, would I go whole-hog and replace the caps and op-amps? I don't think so - the drivers are OK, but at the end of the mods I expect they would limit the results. One COULD mod the drivers too, and I've done it in other systems, and then you'd have something. That 8" cone needs some work, IMHO. ...and in my experience, the LM3886 chips sound better at 22-24 volts. Here they are only getting 15. But that's another story. The schematic above for the HS80M is the correct one. The initial disassembly is not hard but is a bit surgical - you have to operate in tight space to detach the speaker wires. [One of mine was tighter than the other] In particular, the tan 2-wire connector for the front LED is bundled with the speaker wires and needs to be desoldered from the amp board. Nearby there is a zip-tie around the speaker wire bundle that needs to be clipped. The other connectors pull off as predicted, and then the whole power assembly will lift out. Detach the internal heat sink from the external heat sink. The amp board is single sided with various wire jumpers on the non-copper side. The jumper wire labeled R622 is the cleanest place to disconnect the limiter, merely by cutting. On my HS8, the label for R622 was covered by the bracket that mounts the board to the heat sink. It is parallel to and right beside a 1/4 W 1K resistor that measures 1.1K ohms in place. The jumper wire should have continuity with pin 3 of the LM3886 amp chip (IC601). Cut the R622 jumper wire and you are done. Add more thermal paste when you put the heat sinks back together, and clean up the amp board holes to reinsert the LED connector. You'll have to resolder if you want the LEDs to work. Here are two photos - the tan LED connector to the amp board, and the jumper wire to cut, immediately next to the mounting bracket. Attachment Deleted |
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Post by francolargo on May 28, 2015 12:05:33 GMT -6
FWIW, I've been listening to the modded HS8s using a very 'high purity' balanced signal from ESS 9018 DAC. They are SO FATIGUING after the limiter circuit was removed! More punch, yes. But I'm sorry I did it. I like to be able to test presentations at any volume. That 8" driver just can't handle the signal it gets. Maybe the other circuit mods will clean up the signal a bit, but that still doesn't say much for the driver! What it needs is either a full 'Enable' treatment (search on DIYAudio), or to be replaced with a more capable 8" unit! So, unless your ears are very close to the HS8s, when it comes to mods I suggest "all or nothing at all".
Frank
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Post by jeromemason on Jun 3, 2015 17:57:27 GMT -6
You need to fully modify them. Audio grade electrolytics and a good poly's in the eq and pre sections. Increasing to 22uf extends the lowend, you could even try 120nf where the 100nf are if you wanted to go deeper, although, they go plenty low after the 22's. Elna Similic II is the cap of my choice, Wima's for poly's, in the amp section I believe I went with some nichicon audio's as well, there's only a couple near the signal. You could also experiment with a lower ESR in the power section.
What you're hearing is the speaker being opened up after cutting the limiter. NS10's, HS80's etc are not that flattering of a speaker, they will produce ear fatigue on their own, even with the limiter, you've only opened the speaker up now, you're not being spared anything. This is a positive though, you're not being spared, but you're not being fooled. Replace the caps, if you can, the op amps with opa2134's in the pre board. I think those opamps in it are like JRC's, I think, not really ideal for smoothness. The cap swap will sweeten the top and pull out the bottom though.
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Post by jeromemason on Jun 13, 2015 3:19:58 GMT -6
Had some extra time tonight after I got done working and went ahead swapped the opamps to the opa2134's. Really does open the monitor up and improves the imaging. Sound was instantly smoother and more punchy. You'd have to spend a ton to match these monitors if you were buying off a shelf, the clarity and and overall sound is outstanding.
A word of wisdom here guys, if you're not familiar with swapping SMD parts don't attempt this, especially on this speaker. The input boards have probably the most sensitive PCB I've ever worked on, it's extremely easy to over heat and lift a pad/trace. I had to really take my time on these and gently work those opamps out, even more so when cleaning and prepping the pads.
If anyone is wanting this done shoot me a message. Definitely is a whole new world from the stock versions.
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Post by hammer8994 on Dec 28, 2015 22:05:34 GMT -6
hey francolargo, sorry for the late post. but did you mod a HS8 or HS80? im a HS8 owner, and the insides look very different to your photos. but yes would love to cut the limiters inside my HS8s but cant find enough specific info to actually do it. a user on Groupdiy has estimated that the removal of an SMD resister would complete the task, (R409). but again there seems to be no confirmation. cheers guys!
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Post by jazznoise on Dec 29, 2015 18:22:17 GMT -6
Any knowledge of the how to's for HS50'? Is the PCB the same?
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Post by hammer8994 on Dec 29, 2015 21:02:34 GMT -6
Pretty sure the HS50s use the same Pcb as the HS80s, the service manual for yours are easy to find on the net. And then just find the jumper they talk about above
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Post by leoaudio13 on Apr 30, 2020 2:32:46 GMT -6
Hi Sirs,
Which OPA2134 should i order ? Just did the limiter bypass yesterday and it gave such wonderful result. I came up on Mouser and there are like 8 types of OPA2134 to choose from ? A recommendation is highly appreciated.
I live in Vietnam so sending my pair to Zenpro is not a good option so I decided to seek for alternatives to mod my HS8 monitors. Im also seeking for a complete part lists for the mod but seems like it is impossible so. Any help would be awesome. Thank you so much.
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