Life experience has taught me that there's no such thing as an overachieving capacitor!!! You would think that capacitors are like every other storage device but they are not! When measuring their capacity, because of leakage they take longer to charge, giving the impression that their capacity has gone up! They certainly don't get better with time! A good LCR Bridge Meter would have shown their true colours... The two power supply filter capacitors also showed over achieving which is a dead giveaway that they are leaking DC and dragging down the transformer, I bet if you put a watt meter on the AC supply and take power consumption measurements before and after the filter capacitor change, you will see a difference! That's a beautiful amplifier, no doubt there! I would have checked the tolerances of everything!!! Yeah I realize that it takes time and time is money, but there are some things in life that are just worth doing! I bet that amplifier would be able to get a clean output a full power all the way to 30Khz no problem... I'm happy to see that you changed capacitors, would love to see more of that!!

@Digiquarium

3 жыл бұрын

This is the truth. To calculate capacitance, the meter uses a calculation based on how long the capacitor takes to charge, so a higher capacitance value always infers an electrically leaky capacitor. Quite a thing to not know about as an engineer...

@zulumax1

3 жыл бұрын

DC leakage will cause capacitance reading to read high, and so will high internal series resistance. Both cause the capacitor to take more time to charge. Measuring capacitor value has little meaning with old capacitors. In my experience, and opinion, DC leakage is more relevant in high voltage tube gear, and ESR readings more relevant in low voltage applications.

@PeterMilanovski

3 жыл бұрын

There's two common capacitor failure modes, the first and most popular one that everyone always checks either visually or with an ESR meter is the capacitor that fails due to high ESR, this failure modes will cause it to heat and either evaporate or leak it's electrolyte or expand it's top or explode! But generally it destroys itself and stop's the equipment from working altogether or properly, simply replace and all is good! The second and least understood is low EPR (Equivalent Parallel Resistance), this failure mode is far worse and is sometimes confused with an ESR failure but it's not. EPR will not show any external sign's of a problem, one giveaway clue is that it's capacity will show up much higher than what it's rated for, this failure mode is the one that will destroy the next component in line with it... Unlike ESR which shows up a lower capacity, EPR is the opposite! To test for EPR, you need an LCR Bridge Meter which usually has a reading for EPR but they chose to call it disapation, usually just the letter D... You can't just look at capacity and ESR when testing capacitors, there's EPR, Quality, phase angle as well... If you don't have an LCR Bridge Meter, one tip I will give you is, get one that can display all the parameters at the same time on one screen! With most you have to push a button to scroll through all the details, there's a good meter on eBay for under $100 that can display full screen! There's an excellent video showing how to use it (it's bloody easy).. if anyone is interested in the video to see if they might want one before they spend any money, just reply to this post and I will post a link to the video, I will warn you though, once you see what this thing can do, you will wonder how you got by without it and you will want one just like I did... Honestly I couldn't get it fast enough LoL... Even if you are not interested in making repairs, you will know how good the capacitors are before you solder them in... So don't delay, get one today!

@mrnmrn1

3 жыл бұрын

You're right capacitance won't go higher with age in case of electrolytics, but they can be way higher than the rated capacitance right out from the factory. Tolarence can be -5/-10...+20/+50% in case of old electrolytics. In case of big reservoir caps, the factory tolerance might be -20...+80% ('Z' tolerance code), because they aimed the highest possible capacitance that they were able to cram into a given package, so there's some 'spare' capacitance to loose from as they age. Newer caps doesn't do that, because they're overly miniaturized, no room for 50% extra capacitance. my.execpc.com/~endlr/table_8.gif But yes, excessive leakage can screw up capacitance measurement readings. Don't forget he measured the big filter caps in-circuit, so they surely had some parallel resistance across them.

Wow: Was not expecting to see the 60V supply drop as much as it did! Thanks!

@zvotaisvfi8678

2 жыл бұрын

Also Regarding recaps - It takes about 75 hours I would guess before caps really "sound burned in" or the rest of the components "settle" again. I agree new caps on first listen are often funny sounding in a way.

One of the best amplifiers I ever owned was the Denon PMA 250 mk1 back in 1988; I was a student living in student accommodation and it got stolen after only a few months; I was gutted. I owned the mk2 and SE versions of the amp subsequently but never thought they lived up to the mk1. I've owned a lot of amps since then, including (falsely) highly regarded amps from the likes of Naim and very highly regarded American amps. I renovated an old Mission Cyrus 1 which blew away a very highly regarded American amp and now proudly sits in my equipment rack, fed by a Benchmark DAC1 and feeding a pair of Focals; incredible sound. Nonetheless, I still go on Ebay every now and then deliberating whether to get a PM250 mk1 for renovation and maybe use it as a headphone amp; such was the impression it left on me when I owned it.

@asbcustom

3 жыл бұрын

My Mission Cyrus 1 is absolutely my favorite amp, feeding a pair of Dick Sequerra Metronome 7's in a smallish room. I never fatigue of that pair-up.

@markmiwurdz202

3 жыл бұрын

@David Griffin. You may already know this. I'm sure I read a glowing review of the Denon PMA 250 Mk1 somewhere back in the last century (1980's). Apparently when Denon were trying to get into the UK hi-fi market, they looked at all the high end U.K. equipment. Denon then designed and built the PMA 250 amplifier with the UK "audiophile" in mind but at an "entry-level" price. I think this amp. is where Denon got their foothold in the U.K. market and built their reputation on. Stay safe and well.

@davidgriffin79

3 жыл бұрын

@@markmiwurdz202 I remember a review in "Hi-Fi Answers" (1988) where the reviewer preferred the Denon to a highly respected Audiolab (I think it was the 8000 that was out at that time).

@markmiwurdz202

3 жыл бұрын

@David Griffin. The Audiolab 8000 amplifier was a piece of kit that I aspired to own, but never did. I vaguely remember Audiolab getting in to financial problems and they were partnered/bought out by TAG. TAG subsequently re-badged/facelifted the various components. Fortunately Audiolab re-emerged under their own name.

Congratulations on reaching 100K subscribers on the KZread there Mr. Dave ! ! !

Thank you for showing the scope setup and connection details. I learned a lot from your detailed description.

We believe in Dave! Consistently knowledgeable and the occasional anecdotes are immensely entertaining. Thank you Dave, we appreciate what you do!

Thanks for sharing Dave, Congrats on the 100K subscribers.

100k subscribers! I don't think you had that a few weeks ago when I learned of your channel. Congrats!!!!!

The 10Khz, 15Khz and 20Khz tests at the end are a fail and show the amp still needs work

@12voltvids

3 жыл бұрын

Signal generator needs work.

@Astralify

3 жыл бұрын

@@12voltvids My phone is my signal generator. I mostly use LuxDeLux's "frequency generator" app. If I need to test things above 22kHz, I generate some FLACs in audacity with the desired frequency, and play them on players (like USB Player Pro) that have the option not to downsample to android's 48kHz system wide resampling. Thankfully, the DAC on my phone goes to 192kHz if for some reason I need higher frequency, but in the range that it matters (20hz-22kHz) for audio equipment testing, it is clean and distortion free. We have it so easy these days.

Very nice work.

Great video always like your work.

Thank you for sharing 👍

On a schematic, how are those thermal diodes oriented with respect to the base, emitter and collector of the transistors?

thanks for sharing

45mA bias at least through outputs makes a huge difference.. Even the wave form at higher frequency will look better.

@pliedtka

3 жыл бұрын

It often makes the amp a bit more stable, depending od the circuit design and out pair matching.

Great inspection, nicely done. Do you work on vintage portable stereos (boom boxes)?

What are your overall thoughts on the quality of Denon amps? I’ve had a couple of Denon receivers over the years and have had good service from them. I currently own a Denon AVR X2600H and so far so good with this one too. Was wondering what your experience has been quality wise with the brand through the years.

If you are measuring the output power of the power supply, why did you hook up your alligator leads to the two positive terminals of the main filter capacitors instead of grounding one lead and hooking the other up to the filter capacitor output lead? Frank Reiser

@12voltvids

3 жыл бұрын

I didn't. I connected the positive to the positive lead of the positive supply and the negative lead to the negative terminal of the negative terminal to measure rail to rail voltage. I know why you were confused because I used 2 red jumpers. Jumper color means nothing.

What can be done to further improve on the high frequency distortion. It looks still horrible even after replacing the caps.

@12voltvids

3 жыл бұрын

Not the amp, Sig gen has some issues I need to investigate.

Why are you not using the duel channel function of your scope?

@12voltvids

3 жыл бұрын

Why do I need to use the dual channel? I can measure each one by itself. Also one of the probes is fuxed.

I have been following for a long time. I have a problem with Sony camera ccd-trv238e Can you help me with this

A sawtooth @ 15khz?!? Fixed?!? Think you still have some bad caps that you haven't found yet. Use your scope and track it back.

@pliedtka

3 жыл бұрын

Sounds bad, measures badly..., saw tooth at 15k 🙄, seriously. Who knows what the circuit topology is. Put 3886, or 3875 inside, problem fixed.

@1959Berre

3 жыл бұрын

Exactly. That 'sinus' looks horrible. The pre amp (tone control) needs a full recap. He should feed the signal in between the pre amp and the end stage to determine where the signal is corrupted by bad parts.

@12voltvids

3 жыл бұрын

It's the generator. Distortion is in the output and guess what the amplifier amplified it.

@12voltvids

3 жыл бұрын

The signal generator is faulty. The distortion actually changes depending on the setting of the output level. Could be the switching power supply that powers the generator. (usb brick) The distortion is there on the input.

@12voltvids

3 жыл бұрын

@Seventh Anubis I don't think there are any in it. It is one of there cheap digital units but it is powered by a usb phone charger and that is where the problem is i think. Will try a different power brick.

Hi , please make a video showing on a circuit diagram to explain the thermal bias. Thanks for this video.

By the way, any time someone makes "moar powa" without unwanted distortion is a time for an e-beer. MOAR POWA!!! :) Sine wave looks nice where it counts most, in the "bulk of the sound" range. Awesome man.

Higher than rated capacity can also be an indicator of a leaky capacitor cause the capacity meter measures the time it takes to charge the capacitor.

@12voltvids

3 жыл бұрын

Electrolytic caps have a +20 -10% tolerance rating. A 1000uf willbmeasure 900 to 1200 and be in spec.

Why was the waveform so badly distorted at higher frequencies? It doesn't look like crossover distortion, looks more like odd order harmonic distortion, just a guess.

Specifications. Power output: 40 watts per channel into 8Ω (stereo) Frequency response: 20Hz to 40kHz. Total harmonic distortion: 0.05% Damping factor: 35. Input sensitivity: 2.5mV (MM), 150mV (line) Signal to noise ratio: 70dB (MM), 90dB (line)

I wonder if when caps age, does their rated maximum power decrease. For instance, take a 25v cap new. In ten years, do you think 25v is still the appropriate value for its rating in real life (not the label itself?) My guess is probably not but it is only a guess. What do you think?

@PeterMilanovski

3 жыл бұрын

No, that won't be a problem! The two problems are ESR and EPR. A capacitor with high ESR will heat and either expand or leak it's electrolyte on the PCB or evaporate it, as it dries out, it will give a lower capacity reading, the worst case scenario is that it explodes or the equipment just stops working.... EPR (Equivalent Parallel Resistance) on the other hand is a little different, there are no signs of failure to see visually, the first clue is the measurement of higher capacity than what it's rated for! Low EPR will leak DC like there's no tomorrow! Whatever component it's connected to will be the one that dies! If you check it's ESR, it would show up extremely low giving the impression that it's in excellent condition but it's not... The only way to know for sure is to use an LCR Bridge Meter which should have the ability to check for disapation, as I said earlier, if the capacitor shows much higher capacity, and you don't have an LCR Bridge Meter, just change it anyway and be on the safe side because if the next component is something that is no longer available, you might as well chuck it out... Also, when replacing capacitors that have or are failing, always check if you can fit the same value but higher voltage version of it, usually the higher voltage version have a lower ESR rating and you will get longer life out of them...

Nice job for an entry level amp. Anyway, it could be interesting to probe the signal coming out the preamp, just to check if the distortion and bandwidth limitation had nothing to do with a decoupling cap there, or a bad transistor. Anyway, these low cost models drom the late 70' were rarely that well built, many of these had unsufficient performances to comply with DIN norms about HiFi quality material. But I also guess you can't expect better results without a lot more time, and an eventual circuits replacement that could definitively solve the problem. Here come limits in budget, and the intention to keep this original.

@12voltvids

3 жыл бұрын

The distortion is the cheap signal generator. Remember this is a 0.05 thd amp which is quite high. Better units were closer to 0.01 and the really good ones 0.003.

Besides no distortion up to a few more watts, you eliminated the crossover distortion.

Hi! Did You know d405&d406 parameters? I have broken one… Thanks!

@12voltvids

8 ай бұрын

I guessed.

Even with the new caps its pretty dire, could use some more work but great vid, are you gonna revisit it ?...considerably better than when you started !...cheers.

@12voltvids

3 жыл бұрын

It's the generator. Bad power to it. When i put it on the scope by itself at higher frequencies it looks the same.

For calibrating the amp to 40 W, why do you turn the chassis-mount pots for each wattmeter to 40W instead of measuring the actual power at the pots (by measuring voltage across, and current through, to each pot lead)? The meters may be off. There may be some components connected to the wattmeters that have drifted over such a long time. I can't believe that there is no scratchiness to the controls.

@mraaron1584

3 жыл бұрын

i cleaned them with Dexoit before sending it in to Dave. when i got both units the volume on the amp was crackly and the selector switch was touchy. the tuner also had touchy switches that would make the stereo light not come on at first i though it was a dead bulb but when u would fiddle with the switches the light would come on after cleaning it went away. also the power switches on both units were very very stiff after cleaning they were smooth as ice.

@PeterMilanovski

3 жыл бұрын

@@mraaron1584 I hope that you are going to finish off the amplifier by replacing the rest of the capacitors! The main filter capacitors showed up a higher capacity than what they should be, that means that they have a low EPR and are leaking DC, this type of failure is the type that will definitely destroy something else and never itself! They always will show low ESR and since this is the only thing that people check, it gets missed. It's a beautiful amplifier and it would be a great shame if it lost its original silicon...

@mraaron1584

3 жыл бұрын

@@PeterMilanovski if dave says it needs that then ill do that but if he don't think it needs it ill trust his judgment.

@PeterMilanovski

3 жыл бұрын

@@mraaron1584 it's your choice at the end of the day, I have spent my life in understanding electronic components and their most fundamental level, and I know that when I see a capacitor showing a higher capacity than what it should be, that is the first clue that they are preparing to destroy something else! An ESR measurement will show them as perfect but I will assure you they are not! The reason why they show up a higher capacity isn't because they are getting better with time, they are in fact leaking DC which they shouldn't be and in this type of failure mode they don't get hot, they don't show any signs externally. People don't realise that there are two different types of failure, ESR is only one! Capacitors with high ESR only destroy themselves and the equipment just stops working. Yeah you shouldn't believe everything you read on the internet and that's a given... But sometimes it's the truth and if I'm right, you will have a major failure on your hands eventually. EPR is the worst failure mode! And since the capacitors in question are in the power supply, the transformer is at risk on one end and who knows what else on the other end? I bet if you put a current clamp on the negative DC just after those filter capacitors and turn up the volume you will see just how badly the transformer is struggling to keep up with demand... I personally have 100's of amplifiers and speakers that were designed for all sorts of applications... This is my passion and life's work! What I don't know isn't known yet! The only way to test a capacitor is with an LCR Bridge Meter, an ESR or capacity meter is simply not enough! Those two will not show up the worst failure mode! There's another channel called Mr Carlson's Lab, you might already be watching his videos, if you have then you will be familiar with his own capacitor tester design and how it good it works, well his tester only looks for capacitors which have bad EPR (Equivalent Parallel Resistance). Do yourself a favour and research it! You will see a lot of people who only check for ESR but you will know when you find someone who shows that ESR is like a resistor in series with the capacitor and EPR is like a resistor across the capacitor in parallel... Understand what effect these have on a capacitor... Then you will change out the rest of the older capacitors because you will know...

Why bother with dummy load resistors when your oscilloscope functions as the load?

@12voltvids

3 жыл бұрын

Scope is a very high impedance load. Might as well not even be there.

@PeterMilanovski

3 жыл бұрын

LoL the silly things that people say! I have a better idea, why use the oscilloscope when you can use a multimeter! It's cheaper to replace if something goes wrong... They both have the same impedance, it's not the 4 or 8 ohm's of the load resistor but hey, you never know.... It might work.. let me know how it goes for you.

NEC B617 - NEC D587 (genuine pair, who knows?) Price ranging from $ 10,00 -> $ 33.00 on Ebay.

I just bought the ESR Meter kit that's the same as yours. If it's OK with you I can post some details here on how to obtain one?

@12voltvids

3 жыл бұрын

Go ahead.

@petertryndoch8857

3 жыл бұрын

@@12voltvids You can get the kit from Altronics in Australia. Catalogue number K2574. I'm sure they will ship internationally. But be quick as there are less than a dozen left and they don't intend to restock. Maybe if enough people inquired they may? Failing that you might be lucky in contacting Silicon Chip who own the rights to it. They may sell you the board, code or even a kit, don't know.

@PeterMilanovski

3 жыл бұрын

@@petertryndoch8857 yeah nah don't waste your time, it's just an ESR meter! It doesn't tell you capacity, disapation (EPR Equivalent Parallel Resistance), Quality, phase angle... With just an ESR meter, you are only going to see just one failure mode, a capacitor with low EPR will also show low ESR and yet it will destroy transistors and IC's, a capacitor with high ESR will only destroy itself! Get yourself an LCR Bridge Meter, without it, you don't really know what condition a capacitor is in... A good clue to what you might find in a high ESR capacitor is low capacity, but a capacitor with low EPR will have a much higher capacity than what it should have, EPR level should be as high as possible....

Do you know the production year of the Denons? I don't find a listing for them in the Orion Audio Bluebook 1997. Overseas models perhaps?

@mraaron1584

3 жыл бұрын

i am the owner of them. as far as i can tell they were made some time around 1972-1974. also in North America They seem to have been sold exclusively in Canada I've never seen a us person selling one and when u look at the back of the units they only have a CSA Canada sticker on them no UL sticker. they did appear though to have been sold in Europe and maybe Australia they seemed to be much more common in those areas in the time i was searching for them many popped up for sale in Europe. took me 3-4 years of looking to find these and all past sales i could find seemed to be from Canada none from the us. They also were sold in Japan but Branded as Columbia the one i saw for sale from there had a wood case although idk if that was stock or something someone custom made.

@zulumax1

3 жыл бұрын

@@mraaron1584 Thank you for responding, I have always had a fondness for Denon. I have a Denon DP59L direct drive turntable which is a daily driver, and a Denon DCD-1560 CD player that is a 40 lb. tank, but it needs repair, it won't spin the CD anymore. Still one of the best sounding CD players I have heard, even over the Sony ES series players I have had. Been watching 12voltvids to learn more about these, he is a hard working great guy.

@mraaron1584

3 жыл бұрын

@@zulumax1 i wanted to get a hold of this one because my older bother gave me one when i was younger. but the one he gave me had issues with the right channel making random loud popping sounds had it into a shop back in the 90s 4 times they could never figure out what was wrong with it. so i ended up giving it away. the thing was awesomely loud though these people who lived next door would stay up all hours of the night playing drums so the next day id crank up the denon amp and blast them out with loud rock music lol.

@zulumax1

3 жыл бұрын

@@mraaron1584 I still have my Sansui AU-7700 which is 54 watts per channel and the matching TU-7700 tuner. Have all the owners manuals, service manuals, and brochures. Just replaced the caps that were bad that had failed and the speaker relay. The tuner does not have a dial lamp, but has a red led that runs in a groove. Owned the amp since 1978 and I am kind of emotionally attached to it.

@mraaron1584

3 жыл бұрын

@@zulumax1 just looked one of those up its a nice looking set. i was born in the 80s but idk something about those 70s audio gear they look so much better then the black plastic crap that came after. brushed aluminum, lit up vu meters analog tuner dials a bunch of switches and big knobs it all just looks so much cooler then the crap they make now a days.

I know that it is a 1970s amp because of its metal controls and panel. I would have expected eight TO-3 amplifier transistors. The components, except for that relay, are small. i once worked on a 1970s receiver that had 7 fuses. Three of them kept blowing, and it was due to four shorted TO-3s, but I could not find all of the shorts in the unit. For TO93 transistors in circuit, where I have no idea of pin configuration or if they are NPN or PNP, I just quickly look for shorts between any pin, looking for near 0 ohms. I also look for, with my DMM set on transistor/diode mode, infinite resistance, or a 1 between leads in the other direction. If I get near 0 ohms either way between leads, I assume that the transistor is bad. I know that attached, in circuit resistors fail by increasing their resistance or opening, so I rule out 0 resistance as a fault from attached resistors to the transistor leads. Am I right to check transistors in circuit this way?

Not sure why you're getting that much distortion. I can usually getting a totally clean sine wave up to 20khz plus.

I never understood why you would need a dummy load in place of the speakers for testing audio equipment. I never do in my shop and I get buy with accurate measurements. Thank you for your time with all of my annoying, stupid questions. I only have an NRI diploma in Video Audio Servicing. I am not an EE.

@12voltvids

3 жыл бұрын

If you don't load the output you will get the voltage measurements but since no current is flowing it is not an accurate measurement. I dare you to crank up a tube amplifier with no load. Actually that would be a learning moment for you and then panic mode sets in when the output transformer shorts the primary. Think about why that happens.

@frankreiserm.s.8039

3 жыл бұрын

@@12voltvids How could the primary of a transformer short since there is a lot of impedance in the winding. I could see high current flowing through the primary wire and causing it to melt and open.

@12voltvids

3 жыл бұрын

@@frankreiserm.s.8039 Vacuum tube amplifiers operate at high voltages. The B+ is fed to the primary of the audio output transformer and then to the plate (plates on push pull) which have a grounded cathode. When the tube conducts the electrons flow from the plate to ground which causes a magnetic field in the transformer core which is coupled to the secondary and then to the speaker which produces a magnetic field in the voice coil that moved the cone. With no load there is nowhere for that magnetic energy to go as the field is expanding and collapsing to follow the audio. When the tube goes into cut off (and the opposite tube starts to conduct) there is an instant of high magnetic flux that produces a very high voltage in the primary and remember the primary already has 400+ volts DC on the winding from the power supply. When the field collapses it can easily generate over 1KV in the winding, and because this is a very fine wire, it has very little insulation and that KV or so arcs between the layers of the winding welding the winding in the process and FUBARing the transformer.

Another great video. How was the KFC?

@12voltvids

3 жыл бұрын

What?, Then i remember that receipt. That was actually a note someone had given me with a part number written on the back. I never eat KFC because i know the secret recipe and just make my own! Don't ask what it is. I could tell you the spices but if i gave away the mix ratio i would find myself in big trouble.

I'm not sure that the two power supply caps are pulling there weight, i would gob a couple of 2200uf across both reservoir caps and see if that helps. I imagine if it is the transistor bias, one channel should be different. Just my jibbering lol.

@1959Berre

3 жыл бұрын

The main filter caps are reading too high. Contrary to what much people believe, they are not over achieving. It just means they are "tired" and somewhat dried out, which brings the electrodes closer to each other, hence the higher capacitance reading. I would replace those caps anyhow, it is time.

@zx8401ztv

3 жыл бұрын

@@1959Berre I don't think your comment was supposed to be for me as i said nothing about over achieving, always comment on the very top line.

@srtamplification

3 жыл бұрын

@@zx8401ztv I think that was his way of saying that he agrees with you. Maybe that didn't translate into English. LOL

@zx8401ztv

3 жыл бұрын

@@srtamplification Ooops, i think it's going to be one of those days today :-D

@maxwarfield6699

3 жыл бұрын

NOOB question: By electrodes closer, do you mean the layers of insulation/conductivity within the cap? If so, would that result in a shorted cap? When a cap dries up, doesn't it become open? Please clarify, I'm trying to learn more about caps. Thank you kindly

Might have improved the power output somewhat but the amp still needs a lot of work that distortion is absolutly horrible.

@12voltvids

3 жыл бұрын

Signal generator it kicking out distortion at higher frequencies.

@PeterMilanovski

3 жыл бұрын

@@12voltvids LoL I think that it would have been easier to just make another short video about it than trying to tell everyone in the comments, sure it's always great to get a response but I really feel for you man! I would have not known that the problem was with the sig gen had I not came back to see what's going on in the comments section... Well I hope you get it fixed...

@12voltvids

3 жыл бұрын

@@PeterMilanovski I did make a video on the sig generator.

@PeterMilanovski

3 жыл бұрын

@@12voltvids oh! Okay 👌 either I have missed it in and amongst other notifications or it hasn't shown up... I will look for it.. I really want to know what it was that caused the distortion at the higher frequencies!

Rayed at 40w/channel.

I think it sounded better with the old caps. Audiophile grade caps would have made it sound better.

@12voltvids

3 жыл бұрын

Audiophile grade caps? Snake oil, but if someone willing to pay 20.00 per cap or more is going to be the only one that thinks 8t sounds better. Same goes for cables. I had a guy try to convince me that his 1000.00 directional cables improved the sound. I couldn't hear the difference. I offered to do a blind test where i would switch the cable and had him tell me which cable was which. Guess what. He picked the cheap cable as his expensive cable. Snake oil.

@andershammer9307

3 жыл бұрын

@@12voltvids I used to modify stuff for a living. I only made changes where I heard a difference and you don't need to spend a lot of money. Sometimes education is required to hear the differences. I never did any snake oil.

@andershammer9307

3 жыл бұрын

@@12voltvids If you can't hear a difference then I guess it doesn't matter but what if it did sound better and maybe over time you would get to hear the difference and maybe you would listen to the music more due to less fatigue.

@12voltvids

3 жыл бұрын

@@andershammer9307 As a musician i think I have pretty good ears. My personal system is all tubes and is probably one of the best sounding systems i have heard. I can listen to it all day every day. What I am getting at is many people believe the hype and think the expensive part sounds better. As i demonstrated with a guy I used to work with. He had thousands invested in cables. I changed all his cables for dollar store cables and asked him which ones I had on. When he could see the cables he picked the expensive ones. When he couldn't sometimes he picked the expensive ones and other times the cheap ones. It's psychological in most cases. Same goes for HDMI cables. People think they can see the difference. Yes there are different grades. Higher speed cables required for 4k, and they are required as you will get no picture with lower grade cables, but as long as the cable is hdcp 2.0 it doesn't matter if it is a 9.00 cable or a 900.00 cable the results are exactly they same. Snake oil.

@andershammer9307

3 жыл бұрын

@@12voltvids I may not be a musician but I was known for my ears. I only change things when I can hear a difference. I have a system that is both tube and solid state with full range electrostatic speakers. I worked at a stereo store years ago and we had 2 customers who were part of the Pittsburgh symphony. I have my system tweaked to a point where it sounds the same to me as a live symphony at Synod hall in Oakland PA. I never paid attention to price till after I listened to the product.

I don't understand the point of trying a variety of sine waves...put in a 20kHz square wave and if it comes out as a sine, it has fidelity at 20KHz. Run the power up, and when it clips, THAT is an upper end power delivery. Similarly, do 20Hz square wave (yes, there will be ringing), and find the power limit there. NOW you have legit power ratings--yeah, "the industry" allows more forgiving ratings, but this is honest. Next, check that power through some "flat" speakers with white noise, and give a spectrum analysis--if it ain'tvery flat, then the power rating is BS.

@robertdubard7959

7 ай бұрын

Sorry, that was harsh. This is a GREAT video, with good analysis. I just wish there was a legit standard for power ratings.

Over 60V power rail that gives you 30 V peaks and RMS value of that peak is 21V therefore a maximum of 56W into 8 ohms is possible with this supply. Edit 😺your scope showed it delivering 35W at clip? That has to be low. I continue watching.... Edit again 😺😺and at the end you were getting 42W. I looked at the specs and lo and behold it is rated for 40W into 8 ohms. I still think some power is missing. I would expect it to deliver closer to the theoretical maximum at clipping. Some 10W has gone wandering off? Third edit..😺😺😺The only item that can rob significant power would be those reservoirs (voltage under load must be dropping - do they get warm?). The owner may have to bite the bullet and open his wallet.

@PeterMilanovski

3 жыл бұрын

They will only get warm if they are high in ESR, but not if they are low in EPR (Equivalent Parallel Resistance) which is the failure mode that leak's DC.

@martinda7446

3 жыл бұрын

@@PeterMilanovski For anyone else looking in - Capacitors that approach ideal do not dissipate power. In practice they do a little and if old or faulty - possibly a lot. When you load up a transformer supply by drawing current you will see the voltage drop (in simplest terms) due to the DC winding resistance of the secondary and ant other resistances dropping voltage, wires fuses, switches etc. If the supply has drooped as measured at the reservoir caps, it may be wise to ask if they have become leaky to DC. If they are drawing any appreciable current they will droop the supply and get hot. I have seen this a million times with ancient caps and sometimes they don't just get warm, they get red hot. Reservoir capacitors are in parallel with the supply of course so I don't really understand what Peter was saying. I assure you though big caps in parallel with a supply can and do get very hot when faulty and can cause a droop especially on unregulated simple supplies.

@PeterMilanovski

3 жыл бұрын

@@martinda7446 what I am trying to say is that a capacitor with high ESR will heat! As you have already noted, but a capacitor with low EPR will leak DC and don't get hot themselves, they tend to cause other components to heat which usually results in death for those components, the capacitor itself doesn't show any signs of failure... Please understand that there are two different failure modes to Capacitors... High ESR capacitors heat up and leak electrolyte or bulge their tops and their capacity goes down! Low EPR capacitors don't heat because now they have a capacitor bypass resistor slowly working it's way into a short circuit, and because they are leaking DC, a capacitor tester will take longer to test it, giving the impression that it has more capacity than it should... I don't know how much more specific I can be about the two fundamental failure modes of capacitors? A capacitor with low EPR (which is bad) will also have extremely low ESR, so if all you have is an ESR meter, you will never find the real problem... You need an LCR Bridge Meter which will show everything... Otherwise you will be like trying to see a signal without an oscilloscope!

@martinda7446

3 жыл бұрын

@@PeterMilanovski I will be quite honest and say even though I have been in the industry for over 40 years and have a lovely collection of scopes and bridges I've never come across EPR or its effects...To my knowledge (which is zero..so er..). I knew the equivalent circuit had an Rp (Your EPR?) and I guess I lumped all resistances together...What mechanism it physically takes in a practical device when faulty? I am still thinking where does any dissipated power go if not to heat the device up? If you had low ESR and lowish Rp? I will take your word and brush up..It was NOT on the syllabus in 1980 😸. Thank you Peter.

@martinda7446

3 жыл бұрын

@@PeterMilanovski PS I liked your playlists! Are you in Australia? I lived there in 1976-78 and loved it so much.

PIONEER A-80 NO SOUND LEFT CHANNEL