Author Topic: SB2: to pre-amp or not to pre-amp?  (Read 6375 times)

chadh

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SB2: to pre-amp or not to pre-amp?
« on: January 27, 2007, 04:13:10 PM »
I've had my Bolder modified SB2 in my system for about six months now.  I've been using it with a 6sn7-tubed pre-amp (the QA-001 from Space tech labs) into CI Audio VMB1 monoblocks (chip amps), and now have Omega Super 3 XRS speakers.

This morning, I had my very first little experiment with running the SB2 directly into my amps.  Not a serious attempt to discern differences.  But just   a quick and casual experiment to see what hit me in the face.  To be honest, I was a little scared:  all the comments I'd heard had been that the SB2 direct to amps was definitely the superior way to go.  I'd hate to discover that I've been wasting time (and money) for six months with the pre-amp in the system.

Well, my immediate reaction was - wow.  This sounds so much more airy and spacious.  I felt I got a lot more detail from the music too.  But after a little while, I didn't find myself tapping my foot quite as much.  The sound seemed thinner somehow.  Not thin.  Just thinner than before.

I think the best comparison I can give would be to soup.  Some soups are fragrant with well defined flavours - very tasty and also sophisticated.  Others are hearty, with more robust but less distinct flavours.  Depending on your mood or need, one or other will be more satisfying.  In this case, I think I found the heartier soup (i.e. using the pre-amp) more satisfying.

Some of this may have something to do with the major weakness I perceive in my system.  The upper registers aren't quite as sweet as I would like.  I'm not sure what does this:  maybe the fostex drivers aren't really what I need; maybe (well, without a doubt) my room isn't helping things, and my set-up is compromised.  I think that taking the pre-amp out of the chain emphasized this.

I should also say that my modified SB2 is being used with one of Wayne's original "basic" power supplies, so I have yet to experience the fabled majesty of the SB2 experience with an ultimate II power supply.

Anyway, this is all preliminary, but I thought I'd float it out there to see if anyone had any suggestions, observations or encouragements in any direction.

Chad

Double Ugly

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SB2: to pre-amp or not to pre-amp?
« Reply #1 on: January 28, 2007, 07:18:36 AM »
What modifications were performed to your SB2?

chadh

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SB2: to pre-amp or not to pre-amp?
« Reply #2 on: January 28, 2007, 10:56:16 AM »
I had Wayne do analog mods on the SB2.  No bybees, and with Gen 2 bypass caps.  At the time, Wayne was offering an option to have both Gen 2 and platinum bypass caps, and I can't remember whether I sprung for the platinum or not.  Probably not.

Chad

chadh

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SB2: to pre-amp or not to pre-amp?
« Reply #3 on: January 28, 2007, 11:05:00 AM »
Actually, I'm more profligate than I imagined.  I did get the Gen2 and platinum bypass caps.  But still, no bybees.

Chad

Double Ugly

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SB2: to pre-amp or not to pre-amp?
« Reply #4 on: January 28, 2007, 02:38:29 PM »
For frame of reference, I began w/ a full-up RWA version of the SB2+battery PS, had it bested by Wayne's 'Basic' mods and PS, and finally had the 'Basic' absolutely trounced by the 'Ultimate' PS and additional SB2 mods.  Consequently, the comments to follow are in reference to using the 'Ultimate' PS and my latest addition, a Maui Mods/Aberdeen Components Transporter.

In my system, every addition I've tried so far - be it a preamp, or even a power conditioner - has resulted in some sort of degradation in the sound.  The 'Ultimate' PS immediately took care of any perceived thinness I heard w/ the 'Basic' PS, and my experience w/ the modified Transporter is the same.  Far be it for me or anyone else to claim to have a definitive answer, but my initial thought is that you may want to give the 'Ultimate' PS or a Maui Mods/Aberdeen Components Transporter a listen.  

Point being, it sounds like your system is resolving enough to highlight the limits of your current mods, and it may be necessary to either add a preamp back into the chain or change your current mod configuration to get the musicality you seek.  IME, going direct to my amps w/ a fully modified Transporter or 'Ultimate' PS gave me the air and spaciousness you heard, but with the fullness and organic presence you seek.  

We all have different things we seek from our systems, and it may be that your desire for fullness or warmth or whatever is more than any mods can offer.  In that case, a preamp is probably your best bet.  Even so, I'd definitely try a full-up version of something else before deciding to add another component into the chain.  Once you hear the clarity and air a direct connection offers, it's awfully hard to go back.  In my case, it's proven problematic in that I'd like to have more than one source, but I've yet to find a pre- that doesn't rob me from some aspect I've become accustomed to hearing.  Consequently, until I find a preamp I can't hear, my system will remain single-source.

Given the quality that single source produces, I'm OK with that.  

Obviously other system components (amp(s), cabling, speakers) have a profound impact on what you hear, too, but I really think you should consider trying something almost universally accepted by everyone who's heard it ('Ultimate' PS) before changing anything else.

Hope that helps, even if it's just a little.  :wink:

Take care,

-Jim

tonyptony

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SB2: to pre-amp or not to pre-amp?
« Reply #5 on: January 28, 2007, 04:12:40 PM »
Jim, do you have the Ultimate or Ultimate Mk.II?

Double Ugly

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SB2: to pre-amp or not to pre-amp?
« Reply #6 on: January 28, 2007, 04:47:01 PM »
I owned the very first 'Ultimate' PS, but sold it a few months back to help pay for a modified Transporter.  It was a leap of faith (I hadn't heard a stock Transporter, much less a modified version), but I believe it was (at worst) a lateral move.

That said, I understand the Mk.II is several steps beyond what I had.  If true (and I have no reason to believe otherwise), it should be an amazing PS.

chadh

  • Guest
SB2: to pre-amp or not to pre-amp?
« Reply #7 on: January 29, 2007, 07:47:24 AM »
Thanks for the input, Jim.

I'd be happy to believe there is an uber-power supply for my SB2 in the near future.  But as they are expensive, it's probably not going to happen anytime soon.  Of course, everything's relative, and the power supply looks cheap compared to your modified Transporter.

Anyway, it's nice to float some things by people once in a while to check that I'm not going crazy.  Considering your experiences (and others'), I think you're probably right:  my experiment showed that I could get more out of my system.  Hopefully I'll find out soon enough.  For the moment, though, I'm really enjoying how things sound with the pre-amp in there.  And I think that my next order of business will be to experiment with Louis's new 4.5" hemp drivers for the Super 3 XRS speakers.  I think this is most likely to fix the biggest problem I have, with some brittle sounding upper frequencies.

Who knows:  with new drivers, perhaps I'll actually prefer the SB2 direct to amps even without the power supply upgrade.

Alternatively, while I continue to operate in an untreated room with sub-optimal speaker placement, perhaps all my efforts are essentially polishing a turd!

Chad

miklorsmith

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SB2: to pre-amp or not to pre-amp?
« Reply #8 on: January 29, 2007, 08:00:03 AM »
Interesting stuff.  I'm using (well, server problems aside) a RWA SB3 as transport and feel that it's very nice in this regard.  I have a friend with a Boulder unit that I'll hopefully get to hear soon for comparisons.

For the "sweetness" in the top end, you may want to look into supertweeters.  As good as the Fostexes can be in the top end (pretty nice, I have some 206E boxes), they aren't dedicated drivers to the purpose.  My thought is you won't be giving up much if any of the cohesiveness and beauty of the XOverless sound by adding a ST.

I think they hook directly to the speaker terminals and take a passive feed directly from the main amp.  Since they sit on top of the speaker, you can aim them to "gel" the sound best and also move them front/back to eliminate possible phase problems.

chadh

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SB2: to pre-amp or not to pre-amp?
« Reply #9 on: January 29, 2007, 03:20:16 PM »
Quote from: "miklorsmith"
For the "sweetness" in the top end, you may want to look into supertweeters.  As good as the Fostexes can be in the top end (pretty nice, I have some 206E boxes), they aren't dedicated drivers to the purpose.  My thought is you won't be giving up much if any of the cohesiveness and beauty of the XOverless sound by adding a ST.

Thanks for the suggestion.  I'm completely in the dark on this stuff.  Does your suggestion imply that the weakness I'm hearing is potentially due to the driver not extending far enough in the upper frequencies?  

Any tests I've tried have suggested that my hearing extends to about 17kHz, and the Super 3 XRSs extend to about 18kHz.  I've been wondering whether it's an extension problem, or a system synergy problem, or an acoustic problem, or just a characteristic of the driver.

Chad

miklorsmith

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SB2: to pre-amp or not to pre-amp?
« Reply #10 on: January 29, 2007, 03:41:08 PM »
I don't know that particular driver, but how far a driver extends at the top end is not a qualitative measure of how it sounds that high up.  While the Fostex 206E has a fair amount of energy up high, it can sound a bit hard up there.  Certainly, a dedicated driver can "sparkle" better, leading to the XO/multiple driver arrangement.

I don't know your system, but this might be electronic/cable related too.  I certainly have noticed my Fostexes sound better in the treble (and everywhere) with better upstream stuff.

I've never tried a supertweeter myself, though my Definition Pros have tweeters only above 12 khz.  They seem to be varied in features and design.  Some have variable outputs and frequency where they kick in.  Reports have generally been good from what I've read but how important 50 khz extension is when the redbook format has a native 20 khz brickwall filter is at least questionable.

I haven't seen any reviews comparing use of these devices with hi rez digital or analog vs. redbook.

Two concerns:  I don't think a supertweeter will reduce the output of your mains in the treble.  If their output is "bad", as opposed to just rolled off, a supertweeter won't help that.  Also, if the issue is related to something upstream causing problems, accentuating the upper frequencies might actually exacerbate that.

Pursuing the last 1% indeed.