I worked with a bunch of P2200s (the metered option) back in the late 70s / early 80s so Mark fixing a Yamaha P2201 was Old Home Week for me. But Lord have mercy, the previous guy who "worked" on it was a butcher. And not a good one.
I recall from looking inside a few the sticky residue inside was not from dry ice but cigarette smoke, and the output transistors had covers on.
I recall from looking inside a few the sticky residue inside was not from dry ice but cigarette smoke, and the output transistors had covers on.
I always smile when I see a hand-held, IR-camera being utilized to quickly identify an over-heated component on a board with many possible suspects. If we ONLY had access to such an instrument back in the 1980s. If a bad component weren’t obviously overly warm to the touch, it meant desoldering and lifting a leg of all those in parallel to stumble across the component loading down the supply.
Absolutely. They're useless for genuine temperature measurement but superb for finding the component that is dragging a rail down.
This is interresting. Does that apply for California only or to the US as a whole/rest of the world??
The reason I ask, is I´ve been "fighting" with Jim White of Aesthetix over an IO-Signature.
He got exposed on WhatsBestForum, and when he finnaly "showed up", he claimed a lot of "bull" about having extensively trained
technicians in licensed workshop all over the world. (They don´t).
Fact of the matter is, that NO ONE outside the factory is allowed a schematic of the riaa and the psu.
He never replied to emails before getting on the forum, and after a lot of bull about spam-folders a.o. he finally replied and was pretty
nice, sending some measuring schemes promising to help out.
That didn´t last long though. After third question HE decided, that the gear should be returned to the factory, and after that....... Total silence.
These weigh a small ton. PSU alone with 4 big EI-cores, and shipping these from EU a.o. are extremely expensive (around a couple of thousand
Euro´s).
The thread grew showing several unsatisfied customers stating, that they had been waiting for more than 6 months to get their units back.
If any USA guy (or Californian) could help using that law to help with a factory schematic, it would mean the world to me
Only California. Four states so far have approved similar right to repair laws and Biden made an attempt that was largely ineffective.
It's worth raising the question of "why is this an issue?" when you would not, in a rational world, expect people to buy products that cannot be repaired. I remember the first phone I bought with a battery that could not be replaced. Fought against this as long as possible but the manufacturers have won out by making this uniform practice.
Here's what is missing: the standard business practice of competition. If a company would offer an audio product with both an attractive warranty AND a promise to support right to repair for a specified time (say 20 years) then it would get my attention. But the reality is all manufacturers are doing business only for the bottom line believing that cut-throat pricing is the only way to success. To some extent, suspect that they are right.
Batteries can not be replaced because the phone has to control your movement all the time 🙂 It is on a partial joke or not a joke at all
His closing remarks, and the comments are golden.
Fire up your artisanal popcorn makers, folks
All of this with pesky tantalum coupling caps? I didn't read the entire whining 20 pages but looking at the picture there must be over hundred of them in that thing . That's already a few $$ grands just in caps using good 1:10 rule 🙂
Absolute Sound gave a trophy to Naim Nait 5 amp as a product of a year in category of up to $2000 USD integrated amps. The public was gobsmacked how sublime it sounded having seven Elna 47uf/35V standard el caps as an audio couplers in whole chain from input to output. Still probably better than what most here built 🙂
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I learned this from somebody here: if the capacitor impedance is much smaller than the load impedance it doesn't much matter what the cap is, whether polypropylene, tantalum, or electrolytic, because any non-linearities will be lost in the noise. For example, the impedance of a 47 uF cap at 20 Hz is about 130 ohms, so if the next stage has an input Z of 2.5 ish kohms then a 1% nonlinearity in the capacitor impedance is only 0.05% referenced to the load -- and it's a truly horrible cap to have that much distortion. Cyril Bateman found that only a ceramic disc would have 0.5% distortion; anything else was well below 0.01%. If you're really fussed about electrolytics in the signal chain then use nonpolars because their distortion is an order of magnitude lower than standard ones.
Leakage is another consideration. If you're driving a DC-coupled power amplifier then a few microamps across a 10 K resistor could be a problem, but since electrolytics' leakage is a function of voltage across the device then that might not be a problem assuming the pre-capacitor output stage residual voltage is not far from zero. Here again bipolars do better than their polar brethren.
Moral of the story: if you must use electrolytic coupling capacitors, use big ones, preferably nonpolar unless you have steady bias from the output stage.
Leakage is another consideration. If you're driving a DC-coupled power amplifier then a few microamps across a 10 K resistor could be a problem, but since electrolytics' leakage is a function of voltage across the device then that might not be a problem assuming the pre-capacitor output stage residual voltage is not far from zero. Here again bipolars do better than their polar brethren.
Moral of the story: if you must use electrolytic coupling capacitors, use big ones, preferably nonpolar unless you have steady bias from the output stage.
The original YouTube video has been reposted here:
Mend It Mark The £25,000 Pre Amp that went Wrong Tom Evans Mastergroove SR MKIII
Mend It Mark The £25,000 Pre Amp that went Wrong Tom Evans Mastergroove SR MKIII
Not sure what the all fuss is about. Tom Evans audio has a right to charge $100k for a rusty junk with a poop inside if there is interest. Manufacturer service is always expensive. Don't expect less than $600 from Audio Research for single $ 0.20 resistor change ( shipping included). You want a re-cap ? Prepare $2000 plus . Video should not be posted because it is making people who bought the preamp looking like they were taken while the preamp may actually sound better than $50k phono preamps ( if they are any ) from other manufacturers. Since almost none of you have any meaningful experience with equipment on this price level what is the point in discussing it ?
Douglas Self has researched this. The elcap distortion is related to the signal voltage across the cap. So if you overdimension the cap, the signal voltage across it gets lower. Basically supporting your case.
We should also realise that a cap in the signal path that distorts 0.05% does not mean the amp distorts 0.05% - it will be much lower due to feedback.
I hear nobody whining about the need to replace a transistor that distorts 5% or more (check the curves!) by another one that distorts 'only' 1%.
It's all folklore and good for business!
Jan
I worked in industrial electronics product development for about 7 years. Tantalum’s were used a lot because unlike electrolytics they don’t dry out and they have a very long shelf life. But, they don’t like over voltages or high charging currents. Personally though, I don’t know why one would use these in an audio product. It’s not really a good fit applications wise.
Some of us are engineers who've been doing this for decades and we can determine whether a design is truly innovative or well done. Scraping the labels off chips to obfuscate an ordinary circuit does not impress people who've been around the block some.
Y'know what impresses me? World class performance and decent construction at a reasonable price, which requires Actual Engineering instead of copying selected chapters from the National Semiconductor Applications Manual and sticking the result in a box costing ten times what the electronics do. People like Schiit, Pass Labs, Kef, deliver value for money because they think. As Isambard Brunel said: "An engineer can do for a penny what any fool can for a pound."
The classic case of audiophoolery is Wilson Audio (cue goosed maiden aunts clutching pearls across the Galaxy). Almost none of them come anywhere close to even frequency response, whether on-axis or integrated across the radiation field. Moreover, those architectural looking sub-boxes for the mids and tweeters are reflection factories, which waterfall plots show to a fare-thee-well. But, but, but, the cabinets are made of acoustically perfect synthetic material! Whoop-dee-freaking-do.
Meanwhile the Kef Blade Meta 2s are even on and off-axis, are designed to have minimal reflections and thus a clean waterfall response, and as a result the consensus is that they're a fine sounding speaker which does well in many rooms. By the way, the cabinets are also made of an inert synthetic material, no quarter million dollar price tag necessary. Matter of fact, the top-of-the-line Kef is one twentieth the price of the biggest Wilson, with performance better in every way.
Just as examples to show this isn't a one-of, the big Dynaudio speakers cost more than the Kefs but still way less than the Wilsons, and their behaviour is impeccable. Dutch & Dutch, the same. Dunlavy, idem. And so on and so on and so on.
For the record, I've designed Very Expensive audio gear myself. In the pro audio field, mind you, but there's nothing like a stage monitor laying down a 115 dB sound path +-2 dB from 60 to 15000 Hz to separate the sheep from the goats.
So let's not have this "Oh, oh, you don't know how High End Expensive Audio components should be evaluated!" malarkey. We can measure it and we can listen to it, and I can tell you a whole lot of emperors are wandering around wondering about the chill in their nether regions.
No need to hear, there's enough clues in the video: lots of ICs, too many parts, built like a high school science project...
"Just another preamp" is an adequate description; add "... for 25K" and it's an absolute no no.
KeF Blade and the whole line based on that engineered driver was one of the most hateful sounds I heard from the speaker. While Kef does sometimes engineers nice drivers their speakers are atrocious and mostly engineering types buy them based on the white papers they read. The rest buys them because of aggressive advertising UK audio industry is known for.
IT HAS TO to cost $30k or nobody serious will buy it. Evans has the right to charge $30k for his statement product because he proved himself on the market for decades and no internet repair schmuck has the right to kill his milk cow by making statements by association.
IT HAS TO to cost $30k or nobody serious will buy it. Evans has the right to charge $30k for his statement product because he proved himself on the market for decades and no internet repair schmuck has the right to kill his milk cow by making statements by association.
" No need to hear, there's enough clues in the video: lots of ICs, too many parts, built like a high school science project...
"Just another preamp" is an adequate description; add "... for 25K" and it's an absolute no no."
Oh dear,... my friend owns it and I can hear it anytime I want. It is a nice product but doesn’t make his system better 🙂
I owned JC-1 amps and they were just the amps. Sold them without a hint of regret.
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"Just another preamp" is an adequate description; add "... for 25K" and it's an absolute no no."
Oh dear,... my friend owns it and I can hear it anytime I want. It is a nice product but doesn’t make his system better 🙂
I owned JC-1 amps and they were just the amps. Sold them without a hint of regret.
.
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