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Old 17th December 2006, 08:35 PM   #1
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Default Preamp - DIY vs Audio Research (or similar)

As I'm planning my build of a preamp, I can't help but wonder if I'm going about it the right way. While DIY will give me a solution that's perfectly customized, how will the sound compare to a commercial unit... say the latest tube preamp from Audio Research?

In particular, I'm planning on building the popular fig. 2 on:
http://www.users.globalnet.co.uk/~va...PreProject.htm

Provided I use the design in fig. 2 with decent components (gold clad relays, stepped attenuator, etc), how will it compare to offerrings from Audio Research? BTW, this will be driving an Adcom 5802 amp.
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Old 17th December 2006, 09:37 PM   #2
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A perfectly good question indeed. IMO it will sound very different to an ARC pre. Whether you consider this a good or a bad thing is really a matter of priorities.

ARC really like negative feedback and use lots of it. They also like very stiff power supplies and silicon rectifiers. Pretty much the opposite of your chosen design.

Otoh, other high end preams like Conrad Johnson, started with high feedback designs and gradually 'evolved' to zero feedback.

Finding out what's best for you will cost you either money or effort. Or very possibly both. Good luck.
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Old 18th December 2006, 02:13 AM   #3
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Thanks for the feedback!

Would you mind commenting on the effects of the mentioned characteristics?

I'm not pursuing an AR imitation, but rather a proven design that's nicely balanced. I've blindly chosen the mentioned schem. after seeing multiple references to it on this board. While I understand that it's a matter of personal preference, would you have a different suggestion?
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Old 18th December 2006, 04:25 AM   #4
Sheldon is offline Sheldon  United States
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You might consider the Aikido from www.tubecad.com. You can do it completely DIY - all the documentation is available. A table for a variety of tubes is supplied for choosing gain. As a first timer, you also have the option of getting first class boards for both the preamp and a stepped attenuator. Another advantage it offers is that it offers a very good PSRR, making the power supply simpler.

In the other direction is the 12B4 preamp is a large thread here. It's essentially the same topology as shown in your reference. Simple to build, well documented here. Does require a better power supply to get the best result.

Oh, and this being a DIY site, the answer should be obvious - go DIY.

Sheldon
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Old 18th December 2006, 05:03 AM   #5
Glowbug is offline Glowbug  United States
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I run an ARC SP-9MKII with my homebuilt amps, and the sound quality and build quality are great...although, one of my primary reasons for getting it was a decent MM phono stage. If you don't have a turntable, your options open up a lot. Good phono stages aren't too difficult to build, but making one that's dead silent is a step up from making a quiet line stage.

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Old 18th December 2006, 04:11 PM   #6
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One large advantage of DIY is it opens the door to using higher quality parts. Parts quality is perhaps one of the largest three factors determining sound quality. Most commercial offerings use low-grade, noise and distortion inducing parts: poor resistors, bad capacitors, lower grade transformers and inductors, contacts, switches and, not the least, volume controls.

For an interesting pre, don't forget to consider the passive approach. While not everyone's cup of tea, passive pres get you off the mains, which solves many, many a headache. Search "lightspeed attenuator" for an interesting passive version.
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Old 18th December 2006, 05:20 PM   #7
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I built a linestage (tube rectified, tube regulated - triode connected EF86 with a 6DJ8 white cathode follower) for a friend of mine who also has an ARC SP-8.

He prefers the sound of my DIY unit but is keeping the SP8 as a benchmark and the phono stage. The SP8 uses two sections of a 12AX7 with a feedback loop driven by a 6DJ8.

The best thing about DIY gear is the 'I Made This' feeling and the easy tweakability. The best thing about commercial gear is the quality look (though I prefer my stuff!) and brand recognition.
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Old 18th December 2006, 05:34 PM   #8
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Quote:
Originally posted by kstagger
The best thing about commercial gear is the quality look (though I prefer my stuff!) and brand recognition.

Yeah. And that it has a resale value
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Old 18th December 2006, 09:21 PM   #9
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Quote:
Originally posted by serengetiplains
One large advantage of DIY is it opens the door to using higher quality parts. Parts quality is perhaps one of the largest three factors determining sound quality. Most commercial offerings use low-grade, noise and distortion inducing parts: poor resistors, bad capacitors, lower grade transformers and inductors, contacts, switches and, not the least, volume controls.
None of this really applies to AR, does it ? Last time I looked inside an AR preamp it was full of top quality parts. Not insanely priced snake-oild products, just solid engineer's top shelf stuff.
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Old 18th December 2006, 09:28 PM   #10
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by kstagger
I built a linestage (tube rectified, tube regulated - triode connected EF86 with a 6DJ8 white cathode follower) for a friend of mine who also has an ARC SP-8.

He prefers the sound of my DIY unit but is keeping the SP8 as a benchmark and the phono stage. The SP8 uses two sections of a 12AX7 with a feedback loop driven by a 6DJ8.

The best thing about DIY gear is the 'I Made This' feeling and the easy tweakability. The best thing about commercial gear is the quality look (though I prefer my stuff!) and brand recognition.

at least 4 DIY constructions known from here will run in circles around SP8,soundwise........
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