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Old 27th December 2011, 04:18 AM   #1
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Default Tubes: Are they worth it?

Recently I posted a build on reddit.com, which is a forum for almost anything if any of you are familiar with it. However, at some point it turned from just checking out the amp to arguing about the merits of different kinds of amps. I was wondering if there is any sense to the following message?

They're rated to 1% THD at full power, so 400W RMS. THD isn't proportional to power though, it skyrockets in the last 100 watts or so as the output filter approaches saturation.
To give you an idea:
From 20Hz<f<20kHz, at half the rated power and under, typical THD will be 0.01%, max THD will be 0.05%
At 1W, from 20Hz<f<20kHz, Max THD will be 0.004%, but wait, there's more.
This performance is virtually independant of load, and frequency. THD Vs Frequency is ruler flat, and with stepped loads changes very little, arguably insignificantly, so you have a very high degree of neutrality and transparency.
It suffers a very small degree of signal compression on the highs towards saturation, which is similar to what tubes do. The only difference is that instead of compressing further once it reaches clipping, it hard clips. I avoid all that ******** by by running it at half gain and, for now, half power. On the bright side, my speakers are rated at 102dB 1w/1m, and I can run my system at 11 clip free compression free and distortion free 24/7 without it ever breaking a sweat, not so much for the neighbours though.
The nice thing about class d is that you can put this kind of power and performance into it without a large portion of the cost going into heatsinking. It's cooled by convection and conduction to the plate that it's bolted to and nothing else. If you tried that with a class A amp you'd likely have to double your total cost just in metal and it would still be ******* hot.
Once you get into the range of hundreds of watts all you are doing is buying headroom for spikes which are hardly even necessary.
BS excuses... I've heard them all. There are amps out there that **** the bed completely just from having too capacitive a set of speaker wires attached. You need power built into it to supply the reactive loads without overburdening the amp and supply, otherwise it sounds like ***.
It's kind of amusing in a way to see a guy with a tube amp argue against the need for clean dynamics.... I'll let you off this time. I say that because modern crap that passes for music is largely free of dynamics, but when you crank that **** up it sucks even more power.
You should be aware that the kind of guys from which such arguments originate are really full of it, because they sell "first watt" single transistor 10 dollar worth in parts amps for 10X that. What happens to distortion after that 1W is ******* ugly. What happens to distortion with load is ******* ugly. What happens to distortion with frequency is ******* ugly.
So they get these "first watt" amps, that can only produce reasonable THD for a very specific set of very unrealistic working conditions that it won't ever see in practice, and couple them to room sized horn loaded speakers to get some loudness out of it. They act like instruments in themselves, because "analytical is cold" and they think that has to be other extreme to "warmth" and "musical", with no accurate in between.
What you wind up then with is a system that sounds ******* amazing, if you only ever play simplistic jazz /horn recordings with no dynamics.
On the other hand, while not absolutely perfect, my system can go from Tool, to electronic, to orchestral, which btw, takes a motherload of power and accuracy, to unreal tournament, to the space shuttle blasting off, cars running laps, any movie soundstrack and special effect and sitcom laugh tracks... doesn't fukn matter it rocks them all.
But my amps are also extremely unique, especially in class d land. You would have a very difficult time discerning my amp from any class A... it would sound better in some ways and slightly worse in others. But generally class D will sound like *** even with a good design. Proper effort just doesn't go into them and most everyone lacks the knowhow both in design and all aspects of realization.

Built my first amplifier kit : Music
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Old 27th December 2011, 04:42 AM   #2
GloBug is offline GloBug  Canada
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Don't sweat it.

I was a solid state user, Hifi AND guitar. - It's a generation thing.

I am over 18 months clean.

About the only things tubes to good, is play music.

I can hear it, I can hear what others are talking about. I felt what other guitarists felt.

I would take the slightly higher distortion any day of the week.

I don't know much about class-D amps, and yes there are some nice SS amps out there, but they are few and far between and need to be designed well.

Most tube amps sound good.
Most SS amps are lacking.

Even an idiot like me can build a tube amp that sounds better then anything I can buy at Futureshop, so what does that tell ya.
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Old 27th December 2011, 05:43 AM   #3
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The guy in the reddit thread claims he needs hundreds of watts. He might with the right or even wrong set of speakers. His argument with the First Watt amps is the same against tubes. Don't forget that everyone you meet on the internet is an expert in everything along with being an internet tough guy.

He's happy with a few hundred watts and I'm happy with 10. Who is right?
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Old 27th December 2011, 06:32 AM   #4
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Old 27th December 2011, 07:13 AM   #5
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Quote:
Originally Posted by milsman2 View Post
Recently I posted a build on reddit.com, which is a forum for almost anything if any of you are familiar with it. However, at some point it turned from just checking out the amp to arguing about the merits of different kinds of amps.
Never heard of reddit.com before. My wife calls it a social bookmarking site. Not exactly a place to learn about amplifier design, or the differences between them. Some of the posts below yours are kinda scary.

BTW, tubes are worth every penny, especially the cheap ones.

jeff
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Old 27th December 2011, 07:40 AM   #6
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IMO the best thing to do with a post like that is to shrug and go onto the next one

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Old 27th December 2011, 07:49 AM   #7
Gilgy is offline Gilgy  United Kingdom
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I'm not sure I understand his distinction between "analytical" and "accurate". And I'm not sure I want to understand. Sounds like a typical uninformed internet poster.
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Old 27th December 2011, 09:30 AM   #8
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So he's basically said that class D saves on heatsinking vs class A, which is true enough. He's also saying it's nicely linear throughout its usable range.

Also mentions the lack of dynamics available from low-powered designs. Fair enough - clean headroom is needed to get a large dynamic range. He also points out there's diminishing returns past a couple of hundred watts. This figure will, of course, depend on how loud you like it, listening conditions, speaker sensitivity, etc.

Then he goes on to say that his system is one of the best in the world, being able to play anything you like, loud as you like. He obviously likes it, and thats all he needs in the end.

If it wasn't for all the expletives, I wouldn't mind posts like this so much.

Chris
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Old 27th December 2011, 11:08 AM   #9
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Some of the best solid state designs I've heard are the ones that take advantage of tricks to make up for the problems that SS has. For example, my home theater reciever sounds pretty nice because it takes a digital signal, has nice DACs right next store to the discrete chips that amplify the signal and there is all kinds of EQ stuff to play with that modifies the signal in the digital domain. The trick is to use a good signal, HDMI audio supports some very high resolution sources. I wish people cared more about that be no one says a word and we are stuck with music CDs. You can spend billions of dollars making your CD's sound good but it's still a CD.

I think if you were to take the amp section out of the reciever and just have rca plugs on it no one would be interested.

I have heard some really nice sounding SS amps for the record. One was some kind of ebay tripath board that ran directly off an SLA battery. Really suprised me. Kinda high maintenance though.

I have head some super expensive solid state stuff that was just good but not great. Heaps of power of course. That guy was right about orchestral music needing a lot of power. That's why I like solid state, POWER.

Anyone have an active crossover system with tubes above 200hz and SS below that to a woofer? Maybe that would be the best of both worlds.

BTW, you guys who build your own amps are cool! One day I will get into that but I don't feel up to it just yet.
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Old 27th December 2011, 03:51 PM   #10
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Kinda like arguing the merits of Blondes and Brunettes isn't it???

Steve
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