Why does flawed vintage amp sound so good [message #8281] |
Tue, 22 June 2004 08:48 |
hurdy_gurdyman
Messages: 416 Registered: May 2009
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Illuminati (1st Degree) |
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I been reading with interest some of the previous threads about what makes good sounding tube amps and the differences in them. Now, I wish someone could explain to my why my old Scott LK-48-B (222D in kit form)can sound so musical and just plain fun to listen to when the circuit is complex and has several subsonic and ultrasonic filters built into it. I’m sure this would make a square wave look horrible. But, after owning many vintage amps of good repute (tube and ss), this old Scott is the most musically satisfying I've had. I’m including a link to the schematic. The yellow highlights are the filters that I know of. Just one look at that spaghetti-looking mess of circuitry would convince most that it couldn't possibly sound good. Why does it sound good then?Always needing to know why Dave :^) http://f1.pg.photos.yahoo.com/ph/the_hurdy_gurdyman/detail?.dir=/6d5d&.dnm=5289.jpg
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Re: Why does flawed vintage amp sound so good [message #8282 is a reply to message #8281] |
Tue, 22 June 2004 10:21 |
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Wayne Parham
Messages: 18792 Registered: January 2001
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Illuminati (33rd Degree) |
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Hi Dave, Thanks for the link, that's cool. I couldn't see it very well, but maybe if I downloaded it and put it in an image viewer it is high enough resolution it would be crystal clear. Still, from what I could see, it looked like the basic amplifier was a pretty clean push-pull circuit and the "spaghetti-looking mess of circuitry" was mostly tone control circuits. When set flat or disabled, they wouldn't impact the sound at all. So it may be that the design is actually pretty basic and not alarming even to the low-parts-count purist. Then there is also the issue that a filter isn't necessarily made more pure by having a low parts count. If the components are linear and the load perfectly resistive, that's one thing. But if the load is not resistive, particularly if it is also non-linear, then a simple filter is often horribly wrong. In that case, a more pure filter is one that is more complex and compensates for load variations. I don't see that as being much of the case here, because it's really more of a loudspeaker issue than anything else. It's something to consider when making passive crossover components. But I thought it worth mentioning in the context of "circuit simplicity" verses "response purity." These two things aren't necessarily related. And then there's one more thing. This one makes me wince, but I think it's still important to say. Think about how many people make comments about a sound system they are particularly fond of, saying it sounds better than live, or words to that effect. If something sounds "better" than the original source, then it must be "different" than that source. If the goal is accurate reproduction, then this would seem to be a bad thing. Something was added that enhanced the original, or something that wasn't particularly good in the original was removed. But the enhancement was a change, and kept the reproduction from being true to the original. I really like what Siegfried Linkwitz says about the job of a good sound system being its ability to provide an illusion of reality. For many years, I strived to keep things as close to the original as possible, and I still think that's a worthy goal. But after reading his comments, I realized that he's right - No matter how much effort is placed in maintaining "accuracy," it's all an illusion. And being so, the fact is that the best facsimile is the one that is perceived as being best. This is where objective measurement and subjective perception meet. I guess the bottom line is that if this amplifier has done it for you, then the engineers have met their goal. Whatever inaccuracies are present don't seem to be noticable to you, and the things it does right, it must do very right. So maybe it isn't flawed after all. Wayne
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But seriously, folks..... [message #8284 is a reply to message #8283] |
Tue, 22 June 2004 12:08 |
akhilesh
Messages: 1275 Registered: May 2009
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Illuminati (3rd Degree) |
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The old amps, like yours had a few critical parts right....mainly the transformers and resistors. They also used decent capacitors, and almost always used inductors, since cap technology was expensive. This, alongwith not using the preamp section (meanng setting all tones & balance to zero) leads to a sweet sounding amp. The way to upgrade from there: build anew amp with high quality transformers, chokes & caps! IT will probably sound a bit better. But good vintage amps, like yours, Dave, will out perform most new tube amps, even if these cheap new amps have "few components". -akhilesh
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Thanks for the replies [message #8285 is a reply to message #8281] |
Tue, 22 June 2004 14:14 |
hurdy_gurdyman
Messages: 416 Registered: May 2009
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Illuminati (1st Degree) |
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Thanks guys. Whether this amp is "accurate" or not is not all that important to me at this time. It sounds great, so I'm keeping it. ;^) I just have been curious as to why, as the technical side of me is telling that this isn't the way amps are designed anymore. A nice side effect of those subsonic filters is that I don't get massive uncontrolled woofer fluntuations when playing warped records, even with an open baffle. Not sure why my schematic pic is fuzzy. I think maybe Yahoo photos doesn't have good enough resolution. You'd think that, being free, you should get great quality! Free just isn't what it used to be. Dave :^)
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Re: But seriously, folks..... [message #8289 is a reply to message #8286] |
Tue, 22 June 2004 16:36 |
hurdy_gurdyman
Messages: 416 Registered: May 2009
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Illuminati (1st Degree) |
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I don't know if it really makes any difference or not, but I've heard that after an output transformer has about 20 years or so aging put on it, the iron laminations in the core have "aged" enough to cause what is generally considered better sound then it had new. That's the only thing I can think of that would make a vintage amp any better then the same amp built today. BTW, I've noticed the same harshness in the upper mids on my Scott amp. It's small, but there. It seems to be more noticable on some speakers then others. I've heard it is caused by the cera-caps that are used throughout the curcuitry. Replacing these with good poly caps should cure this. I have replaced just the output coupling caps and have noticed a small improvement. One of these days I'll get around to replacing the rest. Dave
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Re: But seriously, folks..... [message #8291 is a reply to message #8286] |
Wed, 23 June 2004 06:49 |
akhilesh
Messages: 1275 Registered: May 2009
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Illuminati (3rd Degree) |
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HI John, Thanx for the post. What i meant was, older amps that use high quality trannies & chokes will outperform CHEAP new tube amps...with cheaped out output trannies & poor power supplies. BTW, taking an older amp like the scott, and doing mods like: eliminating the preamp section, recapping with high quality caps, changing some key resistors....can lead to a pretty darn good amp. I think there are people on the web who do just this. If you want your final amp (yeah right...you KNOW you have the bug and NOTHING is final), i would suggest an amp that is built new, with high quality parts. Should cost you between $500-$2000 in parts, depending on what kind of speakers you have, what circuit topology you need, etc. I agree with Dave's post below that output trannies sound slighlty better after being broken in. THis is typically a 1000 hours or so, depending on the iron. After that, in my OPINION, the differences will be almost too subtle to bother about. hope this helps. -akhilesh
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Re: But seriously, folks..... [message #8293 is a reply to message #8292] |
Wed, 23 June 2004 09:21 |
akhilesh
Messages: 1275 Registered: May 2009
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Illuminati (3rd Degree) |
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Hi John, One thing you may want to consider isa SET amp, with high efficiency speakers. While they don;t measure well....many folks think of these as their "final amps".-akhilesh
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