Beautiful, Butchered Krell KSA-150 Class-A Amplifier Restoration - Avoid Trevor Lees Audio...
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- Опубликовано: 15 сен 2024
- This video covers my restoration of a beautiful, but butchered Krell KSA-150 class-A power amplifier. In this old photo story (my apologies for the dire production quality, yellow text, etc), I document my restoration of this wonderful amplifier.
I purchased this KSA-150 from an unethical Hi-Fi dealer in Melbourne, called Trevor Lees Audio, also trading as ChristophersAudiophileStore on eBay. Mr Lees misrepresented the condition and history of this amplifier both in writing and verbally, saying that no repair work had ever been carried out and that he sold the amp new.
Unfortunately, when I received the amplifier, I discovered that none of this was true along with a horribly executed repair job. Why not just send it back..? Because I was up for the postage BOTH WAYS - nearly $1000, all for the privilege of being lied to. No thanks to PayPal or greasy T and I like to call Mr Lees!
Long story short, I specialise in this sort of thing so I thought stuff it, I'll fix it myself, properly, and just wear the cost. Mr Lees feels hard done by, but never for a moment considered what I had to go through here. Why? Because he doesn't care!
Lees' technician was a little more ethical. He was so embarrassed by his work and that the amp was allowed to be sold in that condition that he called me and apologised, unreservedly, going directly against his employer in the process. That's gutsy. He explained that he had been forced to use the lowest quality parts and execute the cheapest possible repair.
NOTE: Trevor is trying to re-write history by now claiming a completely different story and even trying to say he never sold this KSA-150 to me when I still have the documentation! You can't make this stuff up.
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I did a similar restoration on another KSA-150 back around 2012 or so. That was fun! Grinding out the carbonized board where it had been burned, and rebuilding that area, was the hardest part of the job. Every silicon part was tested, any weak ones replaced, every electrolytic capacitors was replaced other than the main reservoir caps, which should be lifetime parts as they're computer grade.
This was really bad for sure, but not the worst that *I* have seen! I am the Service Tech at Krell. I have seen some SERIOUS BUTCHERY done by monkeys that called themselves Techs. I'll never forget the PAIR of KSA150's that came to us a few years ago. The owner was almost in tears. We told him that to bring them back to Krell Factor Spec was going to be expensive. He was willing to pay whatever it took to "get his babies back" and so, I took it on as a personal challenge, to restore those poor things to their former glory. It took more than 20 hours, but the task was worth it, to see the transformation! The poor things were completely inoperative when they arrived. The monkey had doodled with purple marker along several of the copper traces. (What? Why? It didn't look like someone tracing circuits. It looked like DOODLING!) The power supplies were butchered, wires were run on the boards.. they were a mess. I got them as close to "pristine" as I could. He was very happy to get them back, sounding as good as new. :) Now, I am curious about that burned trace on the power supply... did you run some copper braid across it, and flow solder into it? That's how I repair fried traces at Krell. Fortunately, they are rare. As for the severely BURNED parts of the board... someone BYPASSED the safety circuits, and let this unit BURN for SOME TIME! That had to have filled the place with THICK, acrid smoke! That did NOT just happen in a few seconds. That took MINUTES. Also, those beige sil pads are TOP OF THE LINE, made by Bergquist. They were chosen years ago by our Engineers at Krell for their VERY high performance. :)
Hi, and thanks for your comment! This was bad but keep in mind that it was 12 years ago and I've also seen worse since. Agreed re Berquist and I think most good repairers will be familiar with their products. I've mentioned them here for example: liquidaudio.com.au/krell-ksa-100s-amplifier-repair-restoration-review/ and use Berquist thermal pads in all my premium repairs. The type originally used in these builds tends to stiffen up over time and delaminate when removed, so I replace them as a matter of course. A big thank you to Krell's service department for their historical support, the team has always been extremely helpful in supporting my work as an independent, specialist repairer here in Perth, Western Australia.
@@LiquidAudio You are correct about them stiffening & coming apart, so we always replace them when we remove/replace transistors. If they are not damaged, we leave them be. As long as they haven't been separated, they remain. Sometimes, I've gotten units where someone re-used the old sil pads. Big no-no. As long as Krell exists, I believe we will provide support to the products we can, where QUALITY parts are still available. Once it becomes impossible to obtain QUALITY parts, then some units may reach "end of support". Sadly, there are a number of older digital devices in that category, where the needed chips are long obsolete. Also CD players, where the laser pickups are no longer available. (Cheap knock-offs don't count... and often don't work, or work for long.)
I just bought this of the person you sold it to in Perth , it sounds incredible, so glad i bought it !!😀👌
Very glad to hear you are enjoying her Craig! Amplifiers like this are a universe apart from the average consumer rubbish that most can afford. That's why I recommend this this sort of purchase is the best way forward for most people.
Absolutely brilliant and high quality workmanship Steve. You are the benchmark that all techs should aim for !
You are right that Trevor Lees will get his in the end !
Thanks Sam, it's Mike but I appreciate the comment!
Still so relevant after 8 years. I was educated, and thrilled. And, this is why art is eternally enlightened. Salute, dear friend.
That was a treat for my eyes, You sir, did an amazing job restoring that Krell. That must have been a satisfactory experience. Krell should really only be in the hands of those who appreciate it, I can tell you do.
Fantastic job, that's the way everyone should work on high end equipment or any equipment for that matter. To take the time and repair a unit as fantastic as Krell makes it's so gratifying...thanks for being so patient and caring about your work.
Kudos on the work you did. You're certainly a perfectionist!
Shame on dealers like Trevor Lees - 99% of the end users don't have your expertise and would have had to scrap this lemon.
I'll contact you separately about a KSA-200S I own.
I used to manage a repair shop in Los Angeles and have seen my share of dishonest repairs and sloppy work. Probably customers will never open their units to see what's been done but I have my own high standards to live up to.
As nice as Krell is those amps are their own worst enemy. The heat they generate significantly shortens component life especially capacitors. I have to admit in 40 years of repairing electronics that was the most sanctimonious repair ever. By the way I own a pair of MDA500 mono blocks and have recaped them twice. A close friend bought them from Andy Singer new and I bought them from him when he got the KAS. I have repaired probably a couple dozen Krell amps for others. Also you have to draw the line somewhere when you are doing the repair on someone else's dime. A loving restoration is nice when it belongs to you but it can get crazy expensive otherwise.
I purchased a pair of used KSA-100's and was totally happy for a number of years, bi-amping with big Duntech speakers. They were super reliable but times got tough and had to part with them. As mentioned by others, they had a completely enclosed casing and while they got warm, there were no dramas. Ventilation was the key.
In retirement I have used my knowledge to help friends in repairing/rebuilding their audio equipment and I am constantly amazed by the way previous amateurs have "gotten" at this gear. It just makes the repairs so much more costly as it's the labour component that makes these jobs painful for clients. I'm currently having to rebuild the relay and power supply PCB's on a Marantz Control Console and most of what I'm doing would have been unnecessary had a monkey not stuck his nose in and butchered everything.
As for Trevor and Michael Lees, I have my own opinion of them and it's interesting that they no longer have a shopfront and have pretty much resorted to selling on line.
Great comments and agreed on all fronts.
As much as I loved my MDA-500s ..... and I paid the money to prove that!..... well, as much as I loved the sound and the looks, they were just to damn HOT!!!.... I mean that as in HEAT!! ....and heat is not good. I was always having to send them back in about every two years to repair something. Even with saying that, I still have a soft spot in my heart for them. Now I have Mcintosh 1201's and have never looked back.
MDA-500s are an absolute beast and well done for even owning a pair. You are quite right though, Krell got a lot of things right with these designs, but a few things wrong and thermals were a part of that. Yes, these are class A amplifiers and will need regular maintenance, but there are some failure points that it would be better they didn't have. I'm not surprised the 1201s are good!
Incredible skills! Well done for putting that fantastic amp right, best wishes for your fight to hold Lee's to account
Bravo!!! Great repair on an awesome amp. I used to own a KSA-150, now I own a KSA-250.
Hi, nice repair. these amps always have a slight hum and slight transformer noise. Did your upgrades quiet the amp down ? I also own a KSA 150. Most people dont know these are very tube like amps and sound glorious. It is a piece worth looking for.
Very nicely done! I wish you were closer! I own the same amp and recently had mine completely refurbised by Krell Industries. Superb amp!
I've worked at an audio repair shop for a few months and I've quit that job because I've had to work this way not taking care when reapairing devices.
Thanks for honestly sharing this, good on you for quitting and sorry you had that experience. It's so common in the electronics repair space. I've created a whole page devoted to work like this: liquidaudio.com.au/hall-of-shame/
Exelent work!
And it's so nice to see this old Krells got a second life!
And that is thanks to you!
Very nice to see and nice video!
I owned a KSA-150, long time ago, loved it!
the best from Sweden!
Yes there are cowboys and there are real technicians. You sir, are a real technician and what a great job you have done. I also are a retired electronics technician and appreciate the time and effort that you took in the repair. Great job.
Thanks Stephen, very much appreciated coming from another tech.
Very nice restoration. You must be proud of yourself.
I don't know you, but you are a genius, and a true craftsman.
That looks really nicely done. They don't make class-A amplifiers anymore.
great video a few years back i bought a turntable from Trevor lees Audio on Ebay. Same situation as yourself, the turntable had been so badly repaired lots of damaged. had to get EBay involved, lost half my money and had to put the turntable in the bin karma will get theses bad people
Hi Ian, very sorry to hear you also had a bad experience with Trevor Lees, I wouldn't trust that guy as far as I could throw him. Luckily, I was able to repair the Krell and use it for many years, but I've never seen a worse job than that original repairer did. Lees' technician felt so bad he personally contacted me, we had a long chat and he apologised for the appalling work. I got the impression he felt pressured to do poor-quality work to make the repair as cheap as possible.
Spectacular. You obviously have a strong passion and an innate talent. Top notch stuff right there!
Congrats... is always a pleasure watch a ethical pro in action... keep it that way...
Another Trevor Lees unsatisfied customer has been there, never again. It would have been appropriate I think to send these pictures to Krell in the USA as they need to know what Trevor Lees is doing to their produce. Good to see someone like yourself bringing quality work to a shonky dealer like Trevor lees.
This model Krell gave me the most bass slam than any other amp ever.
Yes , It was a room heater, But what Power.
So true, I still miss mine for the grunt.
Watching this again as my passion is with class A's.
OMG, they uses solid copper bus bars for the speaker output terminals! Amazing!
Hi Mike, thanks for taking the time to demonstrate a painstaking repair of a formidable Krell amplifier. Your video has empowered me to ask a repair tech viable questions regarding the repair/rebuild process and his choice of components he may or may not use on my amp.
I have a Levinson No. 336 (18 years old+) that needs recapping and is offline (lost one channel). Levinson went under for a while (bought by Harmon) and has recently reintroduced itself back into the market. They no longer do any in-house repairs. I'm relegated to "authorized" repair centers that are familiar with ML. After seeing your video I'm concerned with the level of expertise of a given repair tech and have no way of knowing who is truly competent, such as you.
History: My 336 had known "issues" from the start. "Cheap" Phillips caps made in China (I was told) were the culprit that failed - twice. Levinson repaired them under warranty each time but I paid shipping one way (amp weighs 150 lbs)! The amp is amazing and I want to recap and explore a total rebuild/cleaning as you have demonstrated. Here is a quote from a guy who researched caps of varying companies for the rebuild of his ML amp:
** "Mark Levinson 332/333/336 uses 50000uF/125V for Filter supply and Levinson 335 used 50000uF/100V the original China made Philips were replaced by Levinson service bench with United Chemicon 50000uF/125V caps this is the most expensive cap made by United Chemicon. These UCC caps are okay but they have failed many times. Cornell Dubilier makes many types 50000uF/125V(51000uF/125V also Super expensive 51000uF/160V with 200V surge at 3 inches in Diameter and 5.8 inches long to fit in Levinson. These caps Cornell only makes when requested." **
I was made aware that going up on voltage is ok, but "uF must stay at 50k." Also told blue "Nichons" from Mouser were good - need "10% lower ESR" ? All of this is far above my limited knowledge.
My amp also had an issue with the button that brings it out of "sleep." When pressed, sometimes the amp would "double click" and not "wake up." I'd have to press the button 2-3x. Need to know what to say to the tech on consult.
Lastly, I installed three, 20 amp dedicated lines to my listening room (hospital grade outlets). My 336 finally had its own 20A line (before it had 15A shared). The power cord and plug are HD (not detachable IEC) and can handle high amperage. *The midrange opened up a lot.* However, I read that the 336 can handle up to 30A. Is it advisable to upgrade the power cord with a comparable 30A unit with a 30A plug/recepticle upon its rebuild? Thanks in advance for your patience and experienced commentary. - Rick (US)
Hi Rick, thanks for your comment, you raise some really interesting questions. Very good idea to stay with the rated C, but increasing V slightly is fine. The best thing is to measure V at the capacitor with the amp running, that way you can be sure of what rating to use. Caps are critically important. United make some awesome capacitors, as do RIFA/Kemet, Nippon Chemicon, Elna, Panasonic, Sprague, Vishay, Cornell and Nichicon. Get the best you can afford and check specs for ripple current - go with 105 degree C rated and the highest ripple current you can find. You'll see this parameter when sorting in Mouser or other parts suppliers.
The double click is likely switch 'bounce'. You may need to have a tech install a small capacitor across the switch to eliminate this. Finally, yes get good heavy duty copper power cable. Commercial or industrial stuff is often available and rated at over 15A. Bear in mind that the unit will not draw more than 15A, so this is a somewhat academic improvement, but still nice to do.
Let me knows how this one turns out, find someone good to do the work and you will be in business!
Enjoyed watching this.
I may message you for some advice on my Sony TA-N80ES power amplifier - it is working perfectly but the other day whilst checking the BIAS I noticed one of the capacitors is bulging.
Should be easy to replace, but advice is always a good thing.
Hi Craig, thanks for the feedback and feel free to make contact regarding your amp.
Well done!
I favour both of Dale`s resistors that you show in the amp,RN60 and the black power-resistors,there`s nothing better and the replace those with crap....So,once again,well done.
Goodness gracious what a great factory build, hard to believe this happened. Reminds me of Accuphase with build quality.
Subscribed. Glad I found you. (So I will make myself immediately unpopular by saying...)
I never really liked the Krells, apart from the early models. I rebuilt a KSA50, the original Krell, which was put together very differently to your later 150. The transistors were mounted to a pair of big square section heatsinks inside the chassis. This allowed the casework to be nice and clean, with nothing to snag on your trousers, or the cat to have a scratch against. Along with the massive power supply they were very simple devices.
They had a lovely relaxed sound.
Thanks Martin and I definitely know where you are coming from. I'm familiar with the earliest Krells, I'm not a fan of fan cooling (I know..) but these early amps are great sounding units. My 150 sounded excellent to, but only after extensive restoration.
@@LiquidAudio Thanks for the nice reply. I forgot to say well done, and sorry you had to put up with such poor service from someone who obviously isn't short of a few pennies...He is short on honesty and goodwill, though both of which will end up biting him hard on the backside - in time.
No problem and yes, this dealer is well known here in Aus and not well-liked. I've had many emails and calls from people thanking me for the video and wanting to share stories with me. The best one was a call I received from the actual Trevor Lees technician. He was adamant that he did not do the work you see initially in this video, very apologetic and really very embarrassed by the whole thing. It was clear to me that he did in fact make these repairs, but we has probably instructed to do them as quickly and as cheaply as possible!
@@LiquidAudio Even though management looks upon service departments as necessary evils, generating little profit and lots of headaches they can be great for the shop if word gets out they are helpful and thorough. I managed the service department in a large specialist HiFi shop in London W1 during the 80s and 90s and it would have been inconceivable that a Krell would go to a customer in that condition - and if anything the customer didn't like happened - we would bend over backward to make them happy. (Even if sometimes nothing could make them happy...There were a few of those). Surely this chap's customer base will dwindle as he shafts his way to profit. He will have seen your video - wonder what he is thinking?
PPS Which is why you will continue to be successful offering great service. It is the most important thing for a customer to know they can always get professional friendly and real quality help when they need it. Its the big difference between box shifters and specialists.
Thanks for the warning. I was just about to close a deal on a high end BR player and thought might check credentials.
Life is complicated enough without more headaches.
I live in Adelaide and will keep you in mind. I subscribed to your tube channel.
You have made a good work!
What was the value on the Bias you adjusted on the amp?
Thank you very much, there is no bias adjustment, the adjustment is for the DC servo.
How did you repair the damaged circuit board areas where the PCB substrate was charred?
I rebuilt a KSA-150 as well. The power control board up front that contains the inrush current limiting resistors was rather crispy. Frequently turning one of these amps on and off causes heat damage and a lot of it. The green circuit boards were baked brown and every solder joint had become a cold and failing joint from the heat stress. The KSA-150 is also apparently notorious for doing serious PC board burn damage whenever an output or driver decides to become a dead short. Really it may be a great sounding amp but they're slightly prone to self destructing.
Thanks for your comment and I agree. The front panel board is modified in later units and I do this for my customers, improving reliability and thermal performance in this area. I agree, these amps are rather fragile under certain circumstances and the results of output device failure are not pretty. Having said that, the design is incredibly robust in other ways, having the ability to drive a 1 ohm load continuously, for hours on end. I've found that careful, thorough restoration is the best way to insure longevity with these units and works well to improve reliability. I restored my own KSA-150 years ago and it is still running strongly with its current owner.
@@LiquidAudio I've been running a pair of KMA-160 monoblocks since 1997. And those have a history to them. They'd been in a house fire. They had not been burned, but they had been hosed down and put out along with the fire, then left to corrode, full of filth and corruption, for two years in a basement before I bought them for 500 bucks plus shipping. I put 40 labor hours into doing a complete restoration on the pair and they've been totally reliable and looking good for over 20 years now. Electrically speaking the amps were fine, just dirty. ONE output had failed but it had taken out its safety resistors as well so actually it would have run as soon as it was cleaned but I did the best restoration I could manage anyway. Those amps generate a lot of heat but they're first rate for reliability and yes, they're one ohm stable, though I do not need them to do that.
Great job with the deal and the rebuild on those. You've hit the nail on the head there though regarding the labor involved - nothing on this series of amps and others like them is quick and easy!
Liquid Gold, I heard Trevor Lees has renamed his rubbish company as Mr Bean Audio!
I was a big Krell fan in the past but have seen all too much of an increase in sub-standard repair/recondition work in used units being offered for sale. Not just dealers but private sellers watch a few RUclips videos and think they can offer products as fully serviced when they have used inferior parts and a can of Deoxit! I would only buy a used Krell now if it came with a full bill of health from Krell themselves.
Yes one must always be careful, I see a lot of the type of work you are referring to when it comes to me after having been somewhere else first. Thankfully, there are also those of us who specialise in this type of work and offer attention to detail and improvements beyond what even the factory can offer. It costs more to do the work properly of course, which is why folks often go for the other option!
Clearly a top class and capable engineer.
THIS is why I'm so scared trying to buy these amps used. You never know what kind of shoddy work was done to them in the past 20-30 years!
You make a very good point and this is why I encourage my customers to have a proper inspection done prior to purchase, wherever possible. That would have saved me a ton of time in this case.
Your welcome, it's nice to see another pro at work?
Awesome - Just curious what the cost for all the parts was. I think newer amps handle electrostatic speakers better than older ones,
Awesome vid.
@mikefitzman I have repaired many crest amplifiers that burn holes through the board when the PSU caps fail. I grind away all charred areas of the PCB with a dremel tool, then grind up some old PCB and mix with epoxy and fill in the hole or charred area and grind down flat once fully cured. this works well but I was curious if you had other techniques or methods. always looking to improve.
First class job, well done. Good luck.
Thank you for the good job, the ones that has nothing to hide will let any one see what
they are doing.
Hard to believe!
I know Trevour and his brother through few of the audio gear purchases. They are very honest and sincere people as far I know and from my experience.
Anyway, thats a beast amp and looks like a neat job.
Thanks for your comment and kind words. I'm glad you had good experiences, though sadly many folks did not and quite a few people have contacted me to discuss their own bad experiences. The technician who did this, under Trevor's instruction, rang me to apologise, the poor guy was in tears on the phone.
Sure wish I knew how to do this so that I could repair/refurbish my KMA160 mono blocks along with my KSP-7B preamp. I got them used way back in the lat 1980s. I used them fathfully up until 3 years ago when something went wrong and I couldn't tell you which one of the three components I've mentioned went bad. So now they sit collecting dust.
Congratulations, superb restoration.
+Andy Gallacher Thank you very much for the kind words!
Holy cow ..you’re a true artist 🤘
So, what did you do with the charred FR4 laminate under the burnt Emitter-resistors ? The only sensible thing to do, would be grinding it away with a dremel, and patching the hole with a new piece expoxied in. The charred board is conductive and will lead to problems down the road...
***** Hi, thanks for your question and this was an initial concern of mine before commencing the repair work. I may have covered this in a reply elsewhere, but I very carefully removed all the charred board and cleaned the damaged areas with isoprop before measuring the board resistance in the damaged areas. The board material measured within spec, after removal of charred board and thorough cleaning. There was enough thickness left on the board that reworking the surface with new material was not required and I modified the parts placement to lift the resistor bodies above the board, so that a similar failure in the future would not cause the same degree of damage. The damaged areas are all high-current, low imedance parts of the circuit, so marginal changes to the very high resistance of the board material are not actually much of problem here. Carbonised FR4 would be much more of problem in sensistive, high impedance parts of the circuit, but the burnt areas should still never have been left like that by the previous repairer.
What did you do to repair the charred areas of the PC board? Also how did you repair the burnt traces on the PC board you show us early in the video 0:41 ?
+GenerationXT This is a low impedance area and so the issue is mostly cosmetic, though it is still important to remove as much carbon as possible. I removed the carbon using mechanical methods and then scrubbed with isopropanol, repeating this process until I was happy with the result. Final testing involved measuring board impedance in the charred areas it was around the same as undamaged board after I had finished with it. Regards, Mike.
i like the music of this video ,let me know who is the composer
it's especially amazing when you're high as a kite!
Hi Mike, Do you know what kind of wire they used internally to the speaker binding posts?
I would like to replace that on my vintage KAV 500i.
Nice job on this one!
My apologies for the nine years delayed reply! No wire, just solid bus bars in the case of the KSA-150. The KAV series used a quality tin plated multi-stranded copper wire.
Liquid Gold you area genius a true professional artist! Your work is electronic artistry!
Thanks for this. My dad was going to go to Trevor Lees but I will tell him not to go there now.
puppydoglover29 Absolutely no problem, whenever this saves someone from having to deal with Trevor Lees I am happy, tell your Dad to take his business somewhere where they will look after him!
as you both look and sound pro in this sort of repair then you could maybe figure out what problem I have, I got MHC-WZ 5 sony, basically a home hi-fi, I can't hear a sound from the left tweeter but the speakers or tweeters are fine as I tested them both with different amp, so the problem is internal from the unit itself, what could causing this issue do you think?
25 years ago, i repaired an 5.1 amplifier. No sound no picture at the display. This device was NEW, never used. Two pins of the µ controller was in short circuit. The soldering machine was too generous. This device passed the control "successfully" went from japan to france and sell "successfully" as a normal device.
Beautiful amp , but when things go wrong , they really go wrong. All sorts of pretty serious damage. You would think Krell would be more heavy duty.
I agree, a lot of these amps have failed over the years and because of how they are made, it's a time consuming process to remove and test output devices, which tend to be the failure point. They are superbly well-made, but slightly fragile at the same time. The power supplies hold so much energy that when they fail, it tends to be ugly!
check the link you provided for who makes this music, because you have some funky disco music down there, and I hear some cool music to listen to while stoned in this video ...
Well done.
Really nice work. I have been wanting one of these KSA's or a Mark Levinson since I was reading Stereo Review as a teenager in the 80's. I couldn't afford one then and I certainly will not drop that type of cash on "new" today so why not adopt a 30 year old amp and connect with my teenage inner desires. I am sure the Krell will crush my Carver equipment. I can imagine that most of these amps have had some technical issues in the later part of their lives. I only hope that when I do find a good adoptee that it has not been in a barn fire like yours. I really need a gauge of what a 30 year old beast like this is worth on the secondary market. Any suggestions?
Thank you. Many of these will have suffered failures, this is not a problem if the repairs are made properly and with care as I did here. This amp is now better than most others, due to the quality of parts and my attention to detail, so don't be concerned, as long as it has been properly fixed. I'm selling mine at the moment, asking around 3.5K Australian. This is good value even for an unrestored example, let alone one that has recieved this kind of attention. They are also hard to find in really nice cosmetic condition like this. I hope you find one!
Shipping on something that heavy would be a deal breaker for me but thanks for the offer. I am looking at one or two units from a much closer high end reseller that have supposedly been recapped. I need to find out what their definition of recapped means! I have seen a range of prices from $1100 for a working uncapped unit to $2000 for a recapped unit. I am thinking that @ $1100 that may not be a bad deal. If I put another $1000 in new high end caps caps, insulators etc. it could be a win. The only thing I need is info on how to bias it correctly.
By the way I did not mind the music on your video as others have cited. Those folks haven't discovered the fact that the volume knob does wonders if they don't agree with the content :)
This is me to a T lol. Always wanted a big class A Krell or Threshold amp back then. And for years after. And Still!!
Wow ! beautiful amp.
I am located in Perth, Western Australia, for those who have asked!
Hi Mike,Can you help please, i have a 5 channel disco mixer (unpowered) and it has an annoying mains hum noise on the master out, even if all the inputs are turned off, whenever the volume is turned up you can hear the hum.
Ive already replaced 2 x smoothing caps in the psu 1000uf 35v but that didnt do it. It isnt a ground hum definetely mains, do you have any idea what could cause this,it sounds like a power supply noise through the outputs,could faulty diodes in the psu cause hum? or toroidal
Probably a great video, but could not bear the noise!
mute
I have owned a lot of Krell equipment over the years. Some of it sounds spectacular. Most of it is engineered way over the top. First and second generation Krell KSA can be kept running and output devices can be sourced. Every generation 3 and on you better pay attention to capacitors and resistors and keep the amp up with maintenance inspections as if you lose an output transistors you basically cannot repair that channel because matched sets of those transistors are no longer available. RoHS standards have made it impossible for parts runs by the manufacturer to keep these amps up and running. Prior the RoHS Krell could call Motorola and order a run of 400 matched transistors made to their specifications. If you own some this magnificent equipment use it sparingly. There are newer better solutions but boy does that have a price?
Thanks George, transistor matching is still possible and quite viable for Krell and other gear for that matter. You are quite right about the cost of new gear that is similar to this though. I suggest using and enjoying all equipment like this but having it periodically overhauled by someone competent, that's the key.
Krell was unbeatable at it's peak. Worth every penny spent on it's audio accuracy and build quality. Much love from me❤️❤️
Nice work..
Nice job Mike!
Do you have schematic of Slow Start board for KSA 250?
Hi and thank you! I have all the service data for this series, but I was asked to keep it private, which I feel I must respect. The slow start board was definitely a problem area in these amps.
Do you want to send me? I'll keep it deep private.
V. Maleta Krell released it to me, for servicing and repair purposes. Perhaps you should try them to see if they will also release it to you?
Trevor Lees Audio are in Kew aren't they, just near Kew Junction? I think there's also an audiologist in that group of shops, if it's the same store you're talking about I've often wanted to go into that store and have a look around because I'm very interested in stereo systems and electronics. I go past that Trevor Lees Audio store on the tram on my way to work, they have a design on the shop front that looks like a piano keyboard.
I wish you are here in Jakarta so I can often visit your laboratory workshop
what do'es something like this cost? i have been lugging some nad, and polk audio equipment around for 30+ years, time to get them running again. i have been watching many of these vids on fixing this stuff. i find it the most interesting.
The amplifier or the repair? Both are expensive! Thanks for watching the vid!
Good Job !!
Great job and a warning for me as i'm about to buy a Krell KAV 500 i
No problem and thank you. Don't be alarmed by this, but you need a really competent tech to tackle restoring these beasts properly. Visit liquidaudio.com.au for all the details on this restoration, and many others!
beautiful..work or art...
As you said it's really beautiful amp indeed
Was considering a purchase from TL but now will think twice.
nice repair
I wish you where in the US west coast, would love to have you service my Krell amp.
Where are you located? I just brought back from the dead a burnt out KSA300S.
Perth, Western Australia, details in the description.
@vegasvaron, where are you located, Las Vegas?
Profi works !
Very good work.
The big problem with KRELL amps is the layout of the circuitboard which places warm components *way* to close to eachother, thereby causing overheating that either destroys or damages the components.
The vaste majority of KRELL's that i've seen dropped in for repairs, is due to component overheating.
For such a pricy amp's, you'd think they had safer layouts that didn't endanger the components.
PS. You should rank as diamond-standard when it comes to repairs !. Very thorough and clean.
I would take my Marantz PM-84 Mk II to you for a full service if i could, but i live on the other side of the globe,
so i have to drop it in at Marantz in my country and have it serviced and bagged for future sale.
Very kind of you, thank you! Thermal design is critically important, no doubt about it. High component density is part of it and the high power dissipation of semiconductors in Krell designs, given the limited space available and lack of fans is a big factor. Many owners don't realise that class-A amplifiers need check ups and service more often than cool running A/B amps. People use their class-A amps typically until they fail. This is like running a car without changing the oil - at some point it's going to fail. Krell gear is nicely designed for the most part and very well built, but like all manufacturers, they made some goofs and too many of these big amplifiers fail, which is a shame.
Where are you based please?
Dear Are in the business of restoration of Mark Levinson 33X series, i have one 333 in original condition, can you please let me how we can access the condition of main &filter capacitor as long as amp is working in fantastic condition..
Yadvinder Buttar Hi, the only way to do this properly is to take measurements - you need to know about total C, leakage and ESR. The best way to check these parameters is to make sure you are measuring just the capacitor, not other parts of the circuit. Many capacitors will have to be removed to properly assess their conditon, but some may be able to be measured attached to the chassis, but not in circuit. If you don't have an electronics background, or access to proper test and measurement equipment, you may want to leave the assessment to someone who can properly determine their condition for you.
Old video but things never change and you can never take too many pictures. Bad sellers also alter paperwork and photo's - the serial number is one of their favorites (using photoshop), presenting the images to Ebay / Paypal and make you out to be the criminal.
I used to manage a repair shop...I doubt we would take the time and effort to do a repair like this. Maybe if the customer was willing to pay for it. I'd probably send it out to you instead.
Avoid Trevor Lees everyone!
Superb channel!
Thanks for the heads up
Wish you were in the united states i have a sencore sg165 that needs some tlc i cant seem to find the faults
Hm, i wonder what will give better results, sending such a amp to Krell Industries for restoration, or to someone like you...?
+lbochtler This is a good question. Krell is a different company now, compared to when these great amplifiers were made, though I am sure they still do good repair work. The trick is to find someone who really pays attention to the details, whether they work at Krell, or elsewhere. Once you find someone good, keep using them!
Mike Fitzpatrick
So basically its a do it yourself kind of deal then. I dabble in audio restoration myself, but i do not feel condiment enough to work on such a magnificent amp. I think ill just ask around a bit to see what experiences people have made with krell since the change. I need to clarify these things before going out and buying a KSA300 (thats the one i am most fond of look wise, and based on descriptions). Ill see what i can find out. Thank you for your help!
+Mike Fitzpatrick (Liquid Audio) BTW, i just rememberd one fun thing, i have only ever sent out one amp for restoration, a Marantz PM350. It was to a local hifi restorer, and well, to be honest it sounded better pre restoration, but sadly due to it half breaking it had to be done. After that i started restoring amps myself, and had good success so far. Heck i use 2 of the amps i restored to master music :)
+lbochtler Not sure what you mean about about the DIY bit, but definitely don't work on this yourself unless you know what are doing, they are very complex. I work on a lot of audio gear and the Krell stuff is right up there in terms of complexity. It's beautiful though, amazingly well engineered.
+lbochtler If it sounded better pre-resto, you definitely didn't send it to the right guy. I find that old amps respond amazingly well to a thorough overhaul. Again though, it all comes down to the details and many miss those, which is partly why I am now getting so much work in to restore. I don't have time to make videos now unfortunately!
Trevor lees audio ...is a pirate !!
Hello Mike Nice video Can You get a Krell AC3 DTS module ?
Danny Miller Hi Danny, I would have to ask Krell, I suggest you give them a call, ask for Patrick. Regards, Mike.
Or 2 ea dspi56009fj81
I hate PayPal because you can never count on them ,after 7 years and well over a million dollars worth of high end gear traded on Audiogon & EBay PayPal decided to " Freeze " my account ,of course they froze it right after I sold $28,000 worth of McIntosh Monoblocks ,Preamp & Turn Table ,after 7 months PayPal sent me a check out of the blue with no explanation and no answer to my lawyers multiple attempts at contacting them ,that swore me off of trading gear for good unless it's a pick up in person .
Love the Krell KSA like of Class A amps ,I've got a super clean KSA 100 in storage that previously powered my 2 center channel arrays ,one of these days soon I need to get it out & put it to good use .
I tend to agree, though eBay and PayPal have looked after me well since the Krell incident. I recently bought a Quad 405 which was dropped on the way to me. Worked perfectly but had cosmetic damage from the drop. eBay refunded me the full amount and let me keep the amp. I think they've really tightened up their support for buyers anyway. Get that KSA100 out of storage and making music!
you do fine work to far from ny
how much do you charge to restore a fpb600 my amp still works very well but I feel that its time
+Danny Miller Thanks for your query. Restorations are on a case by case basis, there are no set charges, but big amplifiers like the 600 require dozens of hours of work and hundreds of dollars worth of parts. Much depends on how far I go with the resto - do we install new main filter capacitors for example? This simple question can change the cost of the restoration by $1000!!
We don't know the condition of the main filter capacitors or anything else in the amp and that's the point - it always comes down to an inspection and going from there. Are you local, living in Perth somewhere? If you are overseas, shipping will just crush the deal unfortunately...
yes I'm overseas,thanks anyway
Yeah I've dealt with him too , dubious descriptions on eBay took money and never sent the goods . Advertised capacitors n.o.s never sent them out stay right away
please fix the audio the terrible sound hurts my ears.
Just turn up the volume a bit...
You mean turn it off completely ...
Nice job...Looks like one of the channels burned up. Luckily the previous guy..with all his grusome left over non-caring crap knew enuf to balance the amp. Which is the problem with fixing brands like ie: Nikko..transistors have to be balanced . I had enuf days when I picked thru barrels with my beta transistor checker in tow whew. With esr meters now things have gotten a mite easier for caps. especially the smd types
seems to me lots of show but no go....you do not show on the video what have you done to restore the damaged board, you only show the restored "good"board...did you just clean and scrape the carbon or did you apply new solder mask etc??also why replacing good quality parts then left that burned out sprague blue cap?i dont see any value on replacing good resistors, they are quality and not very drift prone so my view is just leave them alone and focus on restoring the burnt areas of the board because it can become conductive when heat damage occurs.there are masks and epoxy products to put that board new..that would be pleasant to see not just replacing good boutique components with new boutique components. anyway hope you take this as a constructive critic and also if you have restored the board actually and or if i missed that in the video, sorry.
+Hugo Barbedo Hi, I would take this as constructive criticism if it had any technical merit, but alas it does not! Your misunderstandings mean a response may be helpful for you and others, so here we go: I have received praise from around the world for my restoration! I did not replace any 'good' parts that were left, only bad replacements that were technically of lower standard than what should have been there. The burnt out areas of the board were very carefully cleaned, restored and tested for conductivity. They were no more conductive than other areas of the board, once they were restored. Also, as I am sure you would understand, these are very low impedance circuit nodes and traces. What this means is that the damaged areas have little or no impact on the flow of current through this part of the circuit. If this had been a radio and were dealing with high impedance RF circuits then things might have been different. Finally the big Sprague was only cosmetically damaged and tested perfectly, as clearly explained. As per your policy, there was no need to replace this very high quality part. Regards, Mike.
Sadly the last 18 months has put many small but high quality repairers out of business
This is true, though thankfully I'm almost always fully booked these days.