Description

After receiving some legacy gear, which included the power amps and a Lexicon DC-1 Digital Control Center, I have done some low-level, low-cost experimenting. Even though it was a better music system than I'd ever had (I'd never *really* had one), I was having trouble. The DC-1 could be configured to sound great for some things, but I never found an acceptable universal setting. At this time, my source was a Sony BDP-S360 BluRay player, and the system doubled as a two-channel av, including Cox Cable. When our cheap projector died, I prevailed upon my wife to perhaps take a hiatus on the av solution. We cancelled cable and moved the BluRay player to the computer in our bedroom. Netflix, DVD's, etc. all through a 24" HD-compatible monitor. Sure, it's a dorm-level solution, but it suits us for now. What was once our main entertainment area suddenly was freed up for two-channel dedication. I briefly used an old Panasonic DVD player as my source. It was old, stored for years, and began skipping a few weeks into use. Probably could have saved it, but I was eager to be rid of it anyway. In my haste, I took what pocket cash I had to the pawn shop around the corner and picked up the more-or-less "current" basic Sony cd changer. I had not yet given up on the DC-1.

Not too long later, a passive preamp showed up on Craigslist. I'd been paying attention to Craigslist long enough to know that this was unusual. I didn't care about the brand--at 50.00, I considered it worth the risk. I was already intrigued by the passive preamp notion, which I think is a natural curiosity for a non-technical person: the simplicity makes it seem easier to grasp and appeals to the logical purist in all of us. Performance was a big question mark, as I had no experience with passives in the least. It turned out to be a PS Audio "PS VK Control Center, and very little info is available online. But how much can be said about such a simple device? I'm sure is was an oddity in 1981 and considered by many to be unworthy of review. I imagine many would have thought it equivalent to reviewing a light switch. Anyway, that's my impression. PS Audio's website reports that it was not well received.

I disconnected the Lexicon and put the VK in its place. I was immediately impressed by the lack of "sizzle." I also, however, sensed the roll-off issue often reported in discussions and tutorials about passives. Looking into this a little, my poor non-technical brain was able to grasp some simple instructions regarding impedance matching/bridging when using a passive pre. Apparently, the roll-off issue is rooted in impedance, and the most important figures to note are your source's output impedance and amplifier's input sensitivity. A couple of sources indicated that an amp's input sensitivity, expressed in ohms, should be at least 10 times the output sensitivity of the source. Well, this Sony cd changer's output impedance was listed at 10 kOhms (up to 50 kOhms), and the input sensitivity of my amps is 33 kOhms. I couldn't ignore the mismatch.

I hemmed and hawed over whether to replace the cd source or just get a dac. I decided that when I would get a dac, it would be a real investment. If I could find a used one for 300.00 that I liked, I would have moved on it. As it turned, out Stereo Design in San Diego had a used Rotel cd changer (I know, changers aren't "audiophile"--I like it anyway), output impedance of 75 ohms. Now that I have a decent source matched well with the amps, the system seems to have clicked.

It all comes out the speakers. I found these Sony SS M3's on Craigslist for a song. Although little is available online, all user reviews are positive. The flagship of this series, the ES SS-M9, was lauded by Stereophile. Anyway, I am quite fond of them. Although I miss low end--these use a 4th order crossover bass reflex with a 6.5" woofer only rated down to 70 Hz--I nevertheless enjoy what I hear. Near field two-way bookshelf listening is plenty of fun. They are biamped using two Rotel RB980BX stereo amps (120 wpc). Way more power on tap than I need. I don't know the engineering principles, but my sense is that the over-amplification helps my passive pre solution perform. I'm guessing the amps are operating Type A most of the time, but I'm still stymied by the whole A/B amplification topic.

I'm always interested in feedback. I'm chilling out for awhile to enjoy the music. I will probably work on finishing this solution before adding more sources. So, power conditioning, as yet unaddressed, is on my radar. I also need some speaker stands. I had them on the floor. Right now they're on dining chairs, the fabric of which is helping to isolate them surprisingly well. My wife is unenthusiastic about this development. I also need a rack for my components, which are currently stacked on an old steamer trunk partially filled with old clothes. I have little doubt that this object colors the sound worse than any other room factor, more because of sound bouncing off of the hollowish object rather than component vibration. components. Following proper room treatment, I'm expecting the sound stage to open up and relax a bit. Currently, I feel that the speakers "disappear" impressively up to medium-high volumes. I think this will improve slightly, and I believe the bottom end roll-off will sweeten. As it is, the move to a passive pre improved the bottom-end roll-off tremendously.
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Components Toggle details

    • Rotel RCC-1055 HDCD
    5 cd carousel 2003 model
    • Rotel RP-1100Q
    Found this on Ebay, non-working. Just needed a new belt. Early 70's.
    • Rotel RC-980bx
    companion piece to amps
    • Rotel RB-980bx
    120 wpc ss stereo amp. I have two of these in a vertical (passive) biamp.
    • Sony SS-M3
    2-way, biampable, cherry veneer. 20kHz-70hz. 1998
    • Mapleshade Bedrock
    These are a nice complement to the speakers.
    • Vertical Audio Cable E312655
    14 awg, 4 cond, 41 stranded oxygen free. In-Wall cable provided by a friend who does av installation. 2m lengths. Four cables housed, each of which used for biwiring.
    • Blue Jeans Cable LC-1
    1' cdp to preamp 2' preamp to amps (2 stereo sets)

Comments 9

You've done well with your system. My first real higher-end piece was a Rotel cdp so I have a fondness for the brand. And I've always loved one brand electronics, because much of the guesswork of mismatched electronics is removed. I just picked up a Rotel tuner and love the sound so as of late I'm looking into a '90s Rotel kit. I'd love to see a photo of your system posted.

mjcmt

Owner
Timrhu, thanks for your kind and encouraging words. I actually read through your system thread a few weeks ago--yeah, the whole thing. :) I also enjoy learning about others' process as they go through components. Yours is a great a read and a very nice system indeed.

I may go the passive route again down the road, Mjcmt. I'm very close to an active biamping project. I think I'll use a Behringer CX3400 or equivalent for awhile and eventually upgrade to a Marchand. If I use an active line level (he does offer a passive line level), then I would consider replacing the active with a passive once again. My amps' input sensitivity is also 1v, but the input impedance is only 33kOhms, not so great with pots. Using this standard active preamp, which is the preamp intended to be matched with these amps (for whatever that's worth), the dynamics are much better and the timing seems tighter. I do miss the smooth transparency of the passive, though.

poprhetor

Owner
Hi Jim,

I've been happy with the stands. I haven't had these speakers on any others, but they're certainly better than no stands at all. The low mids tightened right up and now the sounds seems more effortless. I also like the styling very much. I wish I had the thicker ones, but these will do for the foreseeable future.

poprhetor

how do you like the mapleshade bedrock stands? very unconventional, but i've great reviews.

jimbojrjb

Owner
System edited: Updated sme info. Still need to post pics of my room.

poprhetor

I like the choice of your source, pre, amp, and speakers. Sounds like it should be a nice match.

I've had very good luck w/ passive preamps and sources w/ variable output thereby by-passing a preamp altogether. My current tube amp outputs full power w/ only 1 volt input sensitivity so it is a natural matching w/ passive preamps and really sings w/o the added component to complicate things.

Enjoy!

mjcmt

You've made some interesting choices here with a thorough explanation. Very nice. I have a Harman Kardon amp of the same vintage as your Rotel amp. This amp has a simple design that sounds wonderful. Unfortunately it is sitting in the closet as I don't have a preamp to mate with it.
I've come to believe that exceptional sound can be had very cheaply. Well matched equipment properly setup in a good room can take you there.

timrhu

Cool system and story. I have shopped Craigslist as well.

coolkane

Owner
On second glance, I should have edited more. Oh well, nothing tragic. :)

poprhetor

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