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Greg_L
Banned
That's what I meant. They still work, but cause the sound to be bad.
That's what I meant. They still work, but cause the sound to be bad.
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ecc83
Well-known member
Modern decent quality capacitors are nigh on "perfect". You will see in audiophile circuits electrolytics in both decoupling and coupling modes shunted by a smaller foil cap to "take over" at frequencies that the electro supposedly cannot cope with. Well no more, not needed.
It is true that if there is a significant AC signal voltage across an electrolytic coupler it will produce some distortion but only about 0.01% at worse. Horrific to the audiophool, about 10times better than a valve PI at about 1/2 full chat in a gitamp!
In similar vein some foil caps types produce up to 10X more distortion than others but since we are talking of only about 10 times a level that is barely detectable by the very best analysers, I think guitarists need not worry!
There is no peer reviewed proof that different types of capacitor produce different sound "qualities". Nor do cables or indeed op amps if run within their ratings.
People! Please don't bother with endless, anecdotal "evidence". Well documented, repeatable tests with accompanying .WAV (not MP3!) A and B clips only please!
Dave.
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Greg_L
Banned
antichef
pornk rock
Last year I picked up a 1971 JMP 50 watt head with all original parts. I just assumed the filter caps were bad. They were fine.
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ecc83
Well-known member
Hi Greg,
Well bit of fun and interesting but! Where to begin?
Value of old caps and new?
Ripple voltage on +B before and after?
Are sound levels and gains consistent?
The signal should be identical both times, i.e. re-amped.
I asked for .wavs not MP4 that probably started with MP3.
Did the player know which amp condition was which?
Why were WE told which was which?
Basically you cannot trust anything you see, read or hear on the infernalweb.
Dave.
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Greg_L
Banned
Lol. Including yourself? You strut around talking technical jargon, are we not to trust you?
Look I'm just saying, can bad or going bad parts and pieces affect the tone of an amp? Yes. Is that even debatable?
I don't know if that video is 100% scientifically infallible, but fuck it, what does the guy that uploaded that video gain by lying about it? Do you think Sprague Atom or F&T is gonna cut him a check for potentially convincing billions of people to change out all of their caps? I get it, don't trust anything, but that doesn't mean everything is 100% bullshit with an agenda behind it.
Look I'm just saying, can bad or going bad parts and pieces affect the tone of an amp? Yes. Is that even debatable?
I don't know if that video is 100% scientifically infallible, but fuck it, what does the guy that uploaded that video gain by lying about it? Do you think Sprague Atom or F&T is gonna cut him a check for potentially convincing billions of people to change out all of their caps? I get it, don't trust anything, but that doesn't mean everything is 100% bullshit with an agenda behind it.
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ecc83
Well-known member
Lol. Including yourself? You strut around talking technical jargon, are we not to trust you?
Look I'm just saying, can bad or going bad parts and pieces affect the tone of an amp? Yes. Is that even debatable?
I don't know if that video is 100% scientifically infallible, but fuck it, what does the guy that uploaded that video gain by lying about it? Do you think Sprague Atom or F&T is gonna cut him a check for potentially convincing billions of people to change out all of their caps? I get it, don't trust anything, but that doesn't mean everything is 100% bullshit with an agenda behind it.
No, don't trust me, that doesn't bother me. What does bother me is people ripping others off flogging cables and components that they claim will improve "fidelity" "tone" or whatever. Yes, that video is harmless since no one is being asked to buy "Bloggin's Wondercaps".
"Jargon" is just words you don't understand...Yet. I for instance have no idea what a Sprague Atom or F&T is, but I could try to find out. Six or so years ago I would not have had a clue what most of the people on HR were talking about but I read, learned, asked, made myself look a tit and now have a better idea.
There might be some confusion here between a capacitor that is faulty, lost capacitance or gone leaky and one that is of a different brand. I maintain that if it says 100mfd at 450V on the tin it is as good and will "sound" the same as every other 100mfd. Yes, there are capacitors that are made for specialized jobs. High frequency switch mode power supplies and others for elevated temperature conditions but neither would make a blind bit of difference to a guitar amp.
Dave.
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ranjam
New member
What I noticed the most is that his playing sped up. Maybe new caps make you play faster? 
The sound was practically identical. I heard no objectionable hum, noise, or blocking distortion ('farting'). Maybe playing clean shows more of a difference? But from the before to the after, the tone was similar.
Sort of unrelated, but Guitar Player did this years ago to test guitar cables, where they showed screen shots of the recorded waveform to really try and make you believe cables affected the tone to any appreciable degree. Maybe some screen shots of the recorded riffing?
The bottom line for me that it is 'accepted' that the human eye can tell the difference between 7,000,000 and 10,000,000 colors, depending on which reference you choose to believe. The human ear needs a +5 cent difference to distinguish pitches.
So, to the original question; rather than spend money on an unneeded cap job, check the bias and the tubes!
The sound was practically identical. I heard no objectionable hum, noise, or blocking distortion ('farting'). Maybe playing clean shows more of a difference? But from the before to the after, the tone was similar.
Sort of unrelated, but Guitar Player did this years ago to test guitar cables, where they showed screen shots of the recorded waveform to really try and make you believe cables affected the tone to any appreciable degree. Maybe some screen shots of the recorded riffing?
The bottom line for me that it is 'accepted' that the human eye can tell the difference between 7,000,000 and 10,000,000 colors, depending on which reference you choose to believe. The human ear needs a +5 cent difference to distinguish pitches.
So, to the original question; rather than spend money on an unneeded cap job, check the bias and the tubes!
G
Greg_L
Banned
I do trust you though, even though I don't understand your brit speak much of the time.
But I'm not talking about cables and shit like that. I'm talking about parts that are failing, but haven't failed yet. It can be an amp, a TV, a car, anything. I'm not a TV electrician, but I've had TVs that still work, but don't work well. Something has failed or is failing. It affects the performance of the TV. A cracked spark plug can still work in an engine, but it won't work well. The engine will run poorly. The same goes for the tiny bits and pieces in an amp. Know what I'm saying? I'm not suggesting everyone replace everything because it's old. I'm saying things can go bad before they go totally kaput. Surely you understand.
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ecc83
Well-known member
Yes, I do understand Greg. Certainly a cap coupling anode (forgive Britspeak!) to grid can go leaky and shift the bias on the next valve so that it becomes distorted. Or an HT filter cap can lose its capacity and cause hum. But generally those faults are short lived until the valve burns out or the hum becomes intolerable. the filter cap might eventually go pop!
But these problems are things of the past in my experience, components are vastly more reliable than when I started in electronics (a service man could make a good drink those days!) . As I say, apart from idiots putting caps in the wrong way round and them suffering "collateral damage" they just don't fail anymore.
What I am against is..
1) The idea that because an amp, or any other electronic device, is 10 or so years old the caps MUST be forked and therefore need changing. Ain't Necc' So.
2) Said capacitors MUST be replaced with special types that give an "improved tone". That IMO is bollocks.
Of course some amps etc are such a fuckaroo to get into that IF you suspect a cap problem it can be economically best timewise to do a blanket swap.
Of course, we are now seeing (over here anyway) a flood of very cheap and some say quite good valve amps coming in. Do they use caps etc of the quality of which I speak? Don't know. Time will tell.
Keep rockin' G!
Dave.
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Greg_L
Banned
Yes I don't disagree with any of that, glad we're finally on the same page.
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ecc83
Well-known member
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Greg_L
Banned
You're totally right about people going bananas over brands of caps and stuff. I'm in the process of working on one of my amps right now, I don't know what I'm doing but I'm trying to learn it, and I've been reading all sorts of stuff about how electrolytic cap A sounds sweeter and rounder than cap B, etc. I have to preserve as many of my vintage resistors as possible. I'm like fuck, how bout I just get some stuff that works? I'd be totally okay with that.
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Rski
New member
If that amp was fabricated on surface mount technique, it would be difficult to fix, however, the tube sockets would factor that technique out.
Point to point is sometimes harder to fix, due to multiple component leads soldered onto one lug.
Circuit cards I've seen on some recent builds are somewhat delicate, some tender care on using the right soldering iron, for the job..
Technique is a repair technician craft, that is how to pin point that noise, simply pull the right tube to zero in on the problematic area, then home in on the root cause.
Much like some other repair personnel I duly manage daily, they tend to throw in a plethora of new parts hoping they nail it, not cost effective for the service or the customer.
Point to point is sometimes harder to fix, due to multiple component leads soldered onto one lug.
Circuit cards I've seen on some recent builds are somewhat delicate, some tender care on using the right soldering iron, for the job..
Technique is a repair technician craft, that is how to pin point that noise, simply pull the right tube to zero in on the problematic area, then home in on the root cause.
Much like some other repair personnel I duly manage daily, they tend to throw in a plethora of new parts hoping they nail it, not cost effective for the service or the customer.
fat_fleet
Swollen Member
Yeah, I'm sure I coulda fixed it. The guy didn't charge me anything and even referred me to a couple guys who had more experience (both of which I knew already). He wasn't trying to hose me.
But anyways I sold that amp and bought the Twin.
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ecc83
Well-known member
The skill of the technician is the nub here. Manufacturers do not make product that are easy for any old Joe to fix. Instead they make them as economically as possible* in order to compete and survive in a very hard market. Yes SMTechnology IS very fiddly and difficult to repair but that is why 99% of makers put "No user serviceable parts inside"!
But! Well designed stuff just does not go wrong other than valves. In 4 years total I NEVER had a cap, foil or electrolytic fail in an amp. Never had a metal film resistor fail. I lie! ONCE! A single instance of a 220k very wee MF anode load in a pedal and I saw 100s of those pedals (for valves, bits broke, noisy pots) and tens of 1000s have been sold. I have had fewer than 5 instances of a carbon comp' resistor going noisy (well noisiER, fekkin archaic things!). It IS possible to design even valve amplifiers such that even a gross valve failure doe not damage other components.
*This does NOT mean cheap! It means using components with an adequate safety margin and some "overengineering" of critical parts such as OP valve cathode bias resistors.
It means testing the finished product at elevated drives, mains input voltages and for long periods of time way out of normal usage.
Be it point to point, turret tag, PCB or SMT, If YOUR amp keeps going wrong maybe you bought the wrong brand?
Dave.
rayc
retroreprobate
A bloke I played with had a Fender Twin - early 70's jobbie. he was a hippy and into organic/vintage everything. When it was stolen he replaced it with an original SANSAMP. That was 15 years ago & I'm still scratching my head.
fat_fleet
Swollen Member
Actually been kinda tough to get a good recorded sound out of it. Sounds great in the room but the mic'd sound I'm getting is pretty shrill.
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Greg_L
Banned
Are you close miking it? If so, back that shit off. Try the mic like 6 inches to a foot off the grill pointed halfway to the edge of the cone. Works good for bright cleans.
fat_fleet
Swollen Member
Yeah, I started out close mic'ing with a 57, but now I'm getting some improvement 2-3 feet back. And I switched to an LDC.
It has a line level direct out too, and the tone sounds really good, but there's a shitload of ground loop hum.