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    Tape & Vinyl at center stage in The Lab


    2016 - 05.23

    Recently I decided to take some glamour shots of my stereo setup in “The Lab” and post them to a vintage audio usergroup for others to oogle and discuss. Some of the elements shown here have already been written about individually so I won’t recap that (get it?) in detail here. Clicking on any image will enlarge it, then right click again on the enlarged image if you want to see if in 100% resolution.  Below is a list of the components and links to more descriptive posts on these where available:

    The Cast of Characters:

    Speakers: Marantz HD-770
    Amp: Fisher CA-2310
    Turntable: Marantz 6100
    Reel to Reel: Ampex 960

    The Leslie Model 205 and Electric Trumpet v3.5


    2016 - 01.27

    I’ve made several tweaks to my electric trumpet setup over the last few months and I’m feeling fired up about the results. Most notably, I managed to score a Leslie rotating speaker off Craigslist, which is a rightous acquisition on many levels. I’ve been at many live shows and studio sessions that used a Leslie for organ amplification and having stood next to one, I can attest that although there are many rotary emulations and good quality recordings of rotating speakers out there, there’s simply nothing like being in the room with the real thing. There’s a rich 3D quality when you hear it in person that needs to be experienced in realtime. For a long time I’ve always thought it would be so cool to have one, and now it’s sitting in my living room!!

    My Leslie is a model 205, which is a weird, obscure model. It sat on Craigslist for over a month before I showed up to buy it, probably because it’s a rotosonic model. Rotosonic means that instead of the traditional double horn on top, this model has a rotating drum with a Jensen 6×9 speaker inside of it. Since organs sort of need that screaming, bright sound that a horn gives, most keyboard players would scoff at this substitution. However the trumpet is bright and screamy enough already so the 6×9 speaker works out well for my needs.  Here’s an album of pictures I took (click the arrows to see more):

    Leslie Model 205

    The model 205 is also weird in several other ways as well. It incorporates 5 separate speakers which are independently amplified by a large tube amp and selectable with a relay box. There’s the rotating drum up top with two 6x9s inside (one on each side), another single 6×9 on the bottom inside the rotating drum which spins in the opposite direction, a stationary downward firing 15″ inside the center portion of the cabinet, and a stationary 6×9 which is mounted in one corner on the top. The top drum has a two speed motor for fast and slow rotation and the bottom drum has a fixed, fast-speed motor. The cabinet itself is also slightly unusual, with a different number of louvres than most Leslies and no split in them.

    All in all, it’s a total oddball, but one that I think I can configure nicely to fit my own preferences. When I searched for pictures of this model online I could not find any photos of it, only a single video on YouTube from a guitarist who had reconditioned one. For that reason I have posted a lot of photos here in case someone else is trying to research this obscure model.  The top drum itself is also different than the bottom drum despite the fact that they appear to hold identical 6×9 drivers.  For some reason the designers at Leslie decided the angle the top speakers downward slightly, and added that lightning shaped baffle which partially covers them.  Why?  It just is.  Roll with it.

    Getting this Leslie is a major coup for my little home recording operation, and also for the realtime enjoyment of the sounds as they’re being created. It’s gotten me thinking about the major shifts I’ve gone through in the evolution of my electric setup into what it is now. This feels like the beginning of a new era for me. Looking back, I think I could group my setup into three distinct phases:

    Version 1 (The Muse Cafe Dawning):
    Yamaha Silent Brass as pickup, softshell pedal case on the floor, amplified by a Mesa Boogie wicker-faced guitar amp

    Version 2 (The Crystal Gravy Setup):
    Audio Technica wireless mic as pickup with feedback suppressor and SWR bass amp for amplification with pedals in a hardshell case on top of a keyboard stand

    Version 3 (100% Juice Style):
    Barcus Berry brass transducer as pickup, custom wooden pedalboard on top of keyboard stand, SWR bass amp, DI input box for recording pedalboard (later a Behringer mixer), shure SM57 on straight stand for acoustic sound

    Version 3.5 (The Acropolis Refinements):
    Leslie rotating speaker, PedalGenie rental pedals adding variety, powered Mackie mixer for recording pedalboard, Sennheiser E609 Silver on boom stand for acoustic sound

    Anyhow, I’m very excited about this baby.  You can hear it on this recent recording which I uploaded to my YouTube channel.  It’s being used by the organ in that recording, which is the traditional, easily identifiable way to hear it.  Note that the keyboard is not adding its own leslie effect, so the warbling and the tremolo you hear on the organ is all due to this speaker.  Man this thing is neat!  I’ll have some trumpet recordings with it in the near future…

    Legit 70’s Firepower: The Marantz HD-770s


    2015 - 04.17

    Marantz HD-770 top-end drivers and L-pad array

    As posted about previously, I had encouraged my drummer to get the Marantz HD-440 speakers, since I have very much enjoyed owning a pair of their big brothers, the HD-770s. The “High Definition Series” speakers have walnut veneer cabinets and were built sometime in the 70s. In the Marantz 25th anniversary catalog (dated 1978) they are for sale as the medium tier product underneath the “Design Series”. For a mid-tier product though, these are extremely nice. And as an aside, that 25th anniversary catalog is a feast for the eyes if you’re into this kind of thing… here is a link to it at HiFiEngine.  You’ll need an account to view it but it is easy to create one… it’s worth the effort to check out that super sweet catalog.

    It’s clear they put some thought into the design of these units. The most attention-grabbing feature for me was the 1″ dome driver, which is labeled as a tweeter. I’d call that a misnomer though, since the overall frequency response is given as 33-22kHz +/- 3dB @ 125W of “program material”. Crossover Frequencies are 750, 2300, 5000Hz so that 1-inch “tweeter” is handling 2.3k-5kHz.  I have always been a big fan of dome midranges for their lifelike sound, especially on anything of an earthy, organic variety like acoustic guitar, piano, or exposed vocals. Dome mids do a great job of putting those things “in the room” with you. Interestingly the HD-770 has a stated efficiency of 90dB which is very high for a speaker depending on a 12″ woofer to handle the low end, since the woofer is almost always the limiting factor on efficiency and high efficiency woofers are relatively rare in larger sizes.

    marantz HD series lineup... HD-770s are 2nd from the left

    From the factory HD series units were supplied with a “Vari-Q damping acoustical plug” which you could insert to tune the port if you wanted to change the bass response. The trade-off was more definition in the 50-75Hz range, at the expense of anything below. My speakers were bought secondhand off Craigslist and did not come with this accessory. I see some on ebay with the mention that the original foam is long gone… a running theme. Like the HD-440s, the woofer foam on the HD-770s also crumbles away with time. In my case the previous owner swapped out the original woofer for a replacement driver instead of re-foaming it. This can easily be spotted by the convex woofer dustcap; the original was concave. Given the apparent attention that the Marantz engineers paid to driver selection, I wish he had re-foamed the original. If an opportunity ever presents itself, I would like to acquire the original driver and restore these to their intended stock configuration, although the replacement is doing just fine for the time being.  After searching a while on eBay that seems like a pipe dream though, since a pair in need of re-foaming recently sold for $227.50.  That says something though–one, the original drivers were good and two, the market of people out there enthusiastic about keeping theirs in prime condition remains hot.  My set is also missing the metal ring which mounts around the largest woofer, which is too bad because it does look cool.

    The HD-770s have a three-section resistor (aka L-pad) control panel on the front which allows you to individually adjust the volume of the super tweeter, dome midrange and cone mid-bass drivers. When I built the green speakers for my brother I definitely learned that L-pads are a tremendous asset to any speaker design. They really allow you to tweak the “voicing” of the sound to whatever suits your liking. It can’t be over-emphasized just how much of an impact this has on the sound. Put it this way: never again would I built another set of speakers without L-pads.

    These units have a really funky grille, which has brown fabric which comes outward at the center. I can’t decide if they look cooler with out without the grille on, so I keep the one closer to the door equipped with the grille to protect it from passing foot traffic and the one near the window exposed so I can enjoy the neat appearance of the drivers. Hopefully these units will last me a long time. They are certainly ready to pump out some serious dB’s but still have a soft touch for nuance at the same time. That’s a real nice combination.

    no grille... ... or yes grille?

    A VHS Dubber’s Dream, and a Stereo Pre-Amp Sleeper: The Yamaha AVC-50


    2015 - 04.11

    Having acquired the KM-209 Kenwood power amp, I knew I needed a pre-amp to power it. Since it would be in the living room hooked up to the cable box, I knew it also needed to have a remote control. I’ve never been super into surround sound, so I figured I’d look for something stereo-only. Naturally I wanted to get something older, hoping for a better build quality than modern products… and I didn’t want to pay much. After spending a decent amount of time searching for untis with those qualities, it became clear the best deal would be a receiver or integrated amp which had pre-amp outputs, since a strict pre-amp is overtly aimed at the hi-fi crowd who will spend money for discretes. Remotes began to appear in the early 80s so I looked there, and ended up zeroing in on the Yamaha Natural Sound series.

    In short I was looking for a sleeper: something with great specifications that got lost in the mountains of A/V choices out there, forgotten by the advances of time and the piling-on of unneeded features. And I think I found it. The AVC-50. It’s got inputs from sun-up to sun-down, it’s stereo-only, has a remote, and a killer set of numbers behind it.

    Yamaha AVC-50

    If used as a pre-amp, the AVC-50 has some astoundingly good specs. Specifically it has a 103dB noise isolation between channels and a Total Harmonic Distortion of 0.005% which is… stupifyingly low. That’s not a typo, there’s really two zeros before the 5 in that. That’s very formidible for any pre-amp, even at a snobbish level of audiophile haughtiness. Yet here it is in this obscure seemingly mid-level Yamaha. Sort of strange.

    As to the sound quality, so far I’m very pleased. Between this and the Kenwood power amp that’s doing the grunt work, I can discern a notable improvement in the quality over the outgoing Aiwa. The AVC-50 needed some de-oxit spray to get rid of the crackling when the main volume control was turned, but that was it. I also like the switched power outlets on the back which feed my tape deck and the power amp. Hearing the relays inside all three of them go CLICK when you turn it on is neato.  One thing I do wish it had is tone controls.  There is no bass/treble control and I do miss that, although the speakers it’s driving are already balanced just about right anyway.  It does have a bunch of functions I’m not in need of though: this thing would be amazing for copying VHS tapes back in the day.  There’s a huge amount of video inputs, you can select any audio source while recording video, and it even has a video enhancing circuit with sharpness control.  If you were copying tapes, this thing would have been stellar.

    You could probably find one of these for about $50 if you were patient and persistent. Me, I paid a little extra at $75 to get this one off eBay which came with the remote (many didn’t) and manuals. Although the pictures didn’t really show me, I had a hunch that if it came with the manuals it was probably well-cared for. Indeed it proved to be, and not only did it come with the manual, it also had the receipt for extended warranty (long since expired) and, most interestingly of all, the promotional literature. Retro advertisements can be pretty entertaining to look at sometimes, so I’ve scanned in several pages of this for any who may be interested. The pictures date it. And there’s a lot of effort put into explaining the capabilities of the unit. It’s a long sell. Something that I haven’t seen for a modern product of equivalent standing. Below are all the interesting pages of the large brochure… Check it out:

    Residual Greatness: The Kenwood KM-209 Power Amp


    2015 - 04.09

    So I spent a bunch of time on Craigslist not long ago helping a friend pick out components for his first “real” stereo and when I started doing this I knew that certainly I would come across something for myself that would prove too good of a deal to resist. Predictably that expectation came true in the form of a Kenwood KM-209 power amp from the 80s that I got for just $50. It’s nothing special to look at but it’s got some significant power: rated at 150W RMS into 8Ω with 0.015% THD–from 5Hz to 200kHz (according to HiFiEngine). That’s more wattage than any sane or reasonable person would ever need. And yet here we are.

    Kenwood KM-209

    For a very long time now I’ve had an old Aiwa receiver that’s been the heart of my living room stereo setup. I bought that receiver at Best Buy in the 90s, back in the era when Aiwa minisystems were the bomb and everyone had to have one of those. I admit, the trademark green source buttons with the active one lit in red both looked cool and was quite functional from across the room as well. But an Aiwa is an Aiwa, even if this was their attempt to break out of the minisystem market and be seen as something more legit in the hi-fi world. The receiver is still working, although some of the EQ and DSP buttons seem to have a mind of their own these days.

    Probably what won me over on this unit was the excellent experience I’ve had listening to the Kenwood KA-8300. And also the performance of the Marantz PM750DC Integrated Amp… The KA-8300 said ‘hey Kenwood was actually pretty serious, way back when’, and the PM750DC said ‘products built shortly after the peak of a manufacturer’s greatness can be a great deal’. 80’s Marantz gear worked out pretty good. Let’s give this Kenwood a go. For $50, I couldn’t pass her up.

    The sound is neutral, as far as I can hear.  It certainly goes plenty loud.  As for the unit itself there’s a glowing red display in the center labeled “Power Indicator” which has LED indicators which light up on either side of it for left and right channels. There’s also a toggle switch which lets you switch between 1x and 0.1x for the meters, which is a key feature for power meters.  Nothing exotic or amazing here, but some very solid numbers for a cheap price!

     

    A Relic of their Apogee: The Kenwood KA-8300


    2015 - 04.06

    The Kenwood KA-8300

    Probably the coolest piece of audio gear I have is this 1975 Kenwood integrated amplifer, the KA-8300. Kenwood’s not typically a brand associated with hi-fi now, but back in the day they built some real beasts. And beastly the ‘8300 is, weighing in at 35 pounds. It looks and feels like Kenwood had something to prove with this unit. Power is 80W RMS per channel into 8Ω with 0.1% THD rated from 20Hz to 40kHz. That power rating, being from ’75, is surely conservative. It can also handle 4Ω or 16Ω speakers too, which is somewhat unusual for this time period. The most obvious distinguishing features of the amp are those sweet-looking meters on the front. Watching these is a pleasurable novelty and has actually taught me a bit about the amount of wattage required for typical listening levels…not much! There is a toggle button which swaps the meter range between 3W and 100W. This switch is almost always left on 3W if you want to see the needles bump at all. That surprised me, just how little power is actually used for most listening.

    The KA-8300 has pre-amp outputs which can be used simultaneously with the speaker outputs if you want. When I bought a power amp off Craigslist those came in handy for testing it out. But maybe the most useful feature on this unit are the turnover controls, which are 3-position levers that affect the frequency of the “bass” and “treble” tone knobs. Having the option to move those frequencies around actually makes quite a difference in the usefulness of the bass/treble knobs since it allows the user to tailor the controls to match the speakers being driven. Similarly, the “Loudness” EQ adjustment (which boosts highs/lows for better listening at quiet volumes) has two settings. When listening on the Marantz HD-770s which have a 12″ woofer, setting #2 definitely sounds better whereas on their little brothers, the Marantz HD-440s, switching to setting #1 gave a better bass sound. Loudness is a nifty little circuit which I do prefer to use when the volume is at a low/normal level.

    Although this model was not Kenwood’s top-of-the-line unit, I believe it was only a rung or two below that. For the extreme collector, there is a rare copper-colored faceplace and a slightly higher wattage unit that was otherwise virtually identical in feature-set to this one. Those amps command a much higher asking price but I felt this one hit the sweet spot of equalization features and power for the dollar.

    The KA-8300 is totally built like a tank. The proof is in the pudding too, since when I bought this unit on eBay from a vintage-electronics restoration shop, the faceplate was in perfect condition. As you can imagine, I was quite disappointed to see that it arrived with a bend on the upper right corner despite the fact that the unit was very well pacakged by being wrapped up with bubble wrap and styrofoam around that. 1/4″ aluminum plate doesn’t bend easily and after attempting with a large pliers and channel locks, I gave up and decided to call it character. What I learned in the process is that it would take a lot of force to bend that faceplate, meaning the unit sustained a pretty good impact and has kept right on ticking, functionally. All the knobs and switches work good and I hope this one should be a centerpiece of my audio collection for the rest of my life. Here’s to many late nights of musical enjoyment…

    IMG_5317 v3

    Hi-Fi Entry Point: The Marantz HD-440s


    2014 - 10.25

    Marantz HD440s rightyThe other day at work I was talking with a coworker about stereo equipment and the brand Marantz came up.  I wanted to show him what their amplifiers look like so I did a Google image search for the word Marantz and what do you know, a photo that I took came up in the first couple pages of results!  That’s pretty neat, I thought.  Maybe I ought to post more photos of cool audio equipment that’s made its way into my house.  And thusly begins the first in a series of posts…

    First up is another piece of Marantz gear, the HD-440 speakers.  These actually belong to the drummer I jam with.  He scored them locally for $50 with worn out foam on the woofers.  We spent a couple hours drinking beer and re-foaming them and viola, pretty damn good speakers on the cheap.  They look pretty svelte too, as you can see in the pics.  Those aluminum trim pieces really make them look great with the grilles off.

    While we had the woofers removed for refoaming we took a peek inside.  There’s a lot of foam batting and the crossover consists of two large capacitors, that’s it.  Clearly the Marantz engineers were thinking ‘let’s use good components but use as few parts as possible’.  Since there are only caps that means neither the woofer nor the midrange have a high-cut filter.  They must have purposely selected drivers that had roll-offs close to the capacitor high-pass frequencies.  Either that or they depended on a summed response where the two drivers would combine to form a mostly flat curve.

    This was also my first time trying to re-foam an old woofer.  It wasn’t very hard although it was time consuming.  We also used scotch tape to try pulling out the dustcaps which had been pressed inward.  It worked decent on the woofer but the high range woofer had a dustcap made of fiberous material that started to lose some strands even from the light tug of scotch tape so we quickly gave up on that idea.  I would do a refoam operation again if I found some speakers which I knew were oldies-but-goodies and just needed a new surround to make their triumphant return to greatness.  As with the HD-440s…

    Marantz HD-440

    That Vinyl Sound: The Marantz 6100 Turntable w/ Grado Green & +1%


    2013 - 03.17

    So I picked up one Svelte (with a capital S!) looking turntable a little while back: the Marantz 6100. It had been up on Craigslist for quite some time and I had been eyeing it up, especially since it would match my Marantz amp I like so much. Finally I pulled the trigger. Immediately when I got it home I started noticing a series of issues. This post chronicles all that I’ve done to upgrade and fix it, for anyone who should want to do the same to theirs.

    First thing wrong with it was that only one channel worked. Yikes, that’s a showstopper! Step one was to diagnose: swap the L/R channels as they were connected to my amp to make sure it was the turntable at fault and not the amplifier. It was the turntable. I took the bottom off and used the “beep”/continuity test setting on my multimeter to see where the signal was getting lost. Note that on older turntables like this, with no internal pre-amps, the four connecting pins off your turntable needle/cartridge are, electrically, connected directly to your receiver/amplifier. That means if you’re missing a channel, it’s a continuity problem: The guts of the turntable are simply wires.

    First, I checked the continuity between the connections right at the needle and the solder joints on the inside of the deck. All beeped, so they’re good. Then I checked the solder connections to the end of the RCA ring/tip connectors. Sure enough, one was bad! I was surprised that old RCA jacks would actually fail like that. Hmph. I took a spare RCA cable, and cut off one end. Then I stripped the wires, revealing four different wire paths. I unsoldered the old one and soldered in the new one, making sure to leave a stress-relief knot, so the cable couldn’t be yanked out by accident.

    Second thing I noticed was that the speed of this turntable is slightly slow. I searched around online and found that this is a well-chronicled issue with the model 6100 turntable. It’s driven by an AC motor, so a simple adjustment of the input voltage to the motor won’t remedy this issue. Somewhere online in a forum I saw someone recommend getting a slightly shorter belt. I called a few hi-fi stores and came to the conclusion that 25″ belts are common but 24.9″ belts, in fact, do not exist.

    Then I got the idea of adding something to make the motor shaft very slightly larger in diameter, since that would effectively make it turn the belt faster. Scotch tape, maybe?? Sure enough, it works! At first I added two layers of tape and now my speed went from like 5% slow to like 5% too fast–a thin layer sure goes a long way. I took off one layer of the scotch tape so now it’s just a single loop around the motor shaft. With only one loop, now the turntable runs very, very slightly fast; maybe like 1-2% faster than normal. It’s the kind of thing where, if you’re listening hard for it, you could pick it out with effort, but if you sat down not knowing that the table was ever so slightly fast, you’d probably never notice.

    At first I wondered if it would annoy me (5% too slow DEFINITELY annoyed me!) but after listening to a whole bunch of albums, I think I actually enjoy everything sped up by an almost imperceptible amount. It’s not enough to affect the pitch of familiar records; or if it is, being slightly sharp is less offensive to my ear than being flat. It does add a subtle extra ‘kick’ or energy, having that increase in tempo–an extra bpm or two. I’m digging it!

    Lastly, I was getting distortion in the sound, like the signal was being overdriven or something. I figured since the turntable is nothing more than wires and mechanical support for the stylus, it was probably the stylus. Spoiler alert: it was. The old stylus was a Pickering VX-15 with a dust brush on the front. That dust brush seems like a great idea in theory, but it sort of sucks in reality: seems like it makes the record skip more, and you need lots more tracking force to prevent that. I’m not sure how old that needle was, but from the looks of it… OLD.

    The Pickering was swapped out with a Grado “Green 1” cartridge. Ka-BAM! This baby breathed a whole new life into the 6100. The anti-skate weight was missing from my deck, so I improvised with a couple zinc washers and some thread. I kept getting skips at the very start of every record, even when I had a lot of tracking force on the arm. Adding the anti-skate weight got rid of those skips at the beginning and allowed me to dial back the amount of tracking force needed. It’s still probably too much right now, but it is nice not getting any skips at all even on records which have known spots prone to it. I’ll keep dialing it back in the weeks to come.

    The 6100 has two simple but nice features that I’ve enjoyed: auto-return and auto-shutdown, and buttons to toggle between 33/45 rpm. My other deck, the venerable Pro-Ject Debut III doesn’t have either of these. Auto return/shutdown means that you don’t have to worry about accidentally letting the turntable skip on the last groove all night because you forgot to shut it off, which I’ve totally done. The 33/45 buttons are a very basic feature the Pro-Ject lacks–you actually have to remove the platter and move the belt by hand, which gets old. Maybe that sounds lazy, but you end up yanking on the spindle too much to get the platter off, and I worry about long-term wear that might be causing. It just makes me nervous doing it, so I listened to less 45s on that deck. No longer!

    But oh man, this Grado Green cartridge is awesome. The Pro-Ject Debut III has an Ortofon OM 5E cartridge, and that turntable sounds excellent. For the Marantz, I wanted to get a different brand, for the sake of sonic variety. Since I love my Grado headphones, it was a logical choice to try out their cartridge line. I’d describe the Ortofon as the “cleaner” of the two, and the Grado as the “warmer” of the two. That said, it’s not a jaw-dropping difference between them.

    I hooked up the headphone extension cable and put on my Grado SR-225 headphones for a long listening session this last weekend… now that was really enjoyable!! Laying on the carpet with my eyes closed, blasting familiar recordings and oh yes, hearing a bunch of new details within them, thanks to yet another different listening setup. It’s chicken soup for the soul, just doing nothing but soaking in the awesome sounds of your favorite albums. After the soldering, reassembly, and tweaking this is the reward; not critical listening but blissful listening. I’m going to make it a point to just hang out and listen to records over the next few weeks, reaquainting myself with the collection again and enjoying the tunes. That’s what it’s all about!

    Are you sure you’re sure there’s nothing to an amp?


    2011 - 12.12

    Finding out you’ve been wrong about a long-held assumption is both a triumph and a defeat in the same breath. On one hand it’s awesome learning something and then moving forward with newly discovered truth; on the other hand, oh the wasted years!

    Maybe that’s a tad overdramatic for this particular instance, but I did learn an important lesson this week: amps matter! Being a loudspeaker-building hobbyist, I’ve long been of the opinion that if you’re getting a stereo, you should spend like 90% of your money on the speakers and then just get whatever crappy amp and CD player you find for the cheapest price possible, within reason. I mean, my living room stereo with my large main speakers have been powered by an Aiwa receiver for over a decade now, and it sounds extremely, extremely good. I spent somewhere around $1500 building those speakers and I power them with an amp that costed maybe $150, tops? And the resultant sound quality is, to my ears, better than any speaker system I’ve ever heard in any showroom, anywhere… with the exception of the DALI Helicon 800 which I heard at Decibel Audio in Chicago. Those were mind-blowing speakers. I forget how much those retailed for, but it was well over 5k. And hey, Danish Audiophile Loudspeaker Industries (DALI)? The danes know their speakers. If I have to lose out to someone, it’d be them, for sure. But I digress…

    For the last several months, I’ve had the speakers I built for my brother hooked up to an Onkyo TX-8210 reciever. I figured hey Onkyo is a Japanese brand, reputable name, should be a solid unit, fidelity-wise. When I finally got the speakers finished and started doing my critical listening, I was very happy with the treble, but disappointed in the bass. It sounded a bit bloated, boomy. Certain basslines would have notes that were noticably louder than the rest of the bassline. That should never happen. Some songs which happened to be rooted on those notes were almost unlistenable. I double checked my enclosure math, tried messing with the port length, added more stuffing inside the enclosure. Still boomy. I checked the driver response curves and scratched my head–these drivers both have very flat curves, with the exception of a slight dip at 2.5kHz (the crossover point). Man, did I mess up the enclosure somehow?? It should not be sounding like this. I kinda felt let down, like I was disappointed in my own skills. Maybe I’m not as good at this as I thought.

    Fast forward to last week, when I spotted this puppy on Craigslist for $80–a Marantz PM 750 DC integrated amp from circa 1982 with 80W per channel into 8Ω. Score!

    I’ve always really dug the looks of vintage Marantz gear, with that slightly-gold-tinged silver finish, and the fancy looking typography. It just looks quality, substantial, solidly built, you know? So I jumped at the chance to join the owners club for cheap. This baby was rescued from a junk pile, so it has a few scratches and dings, but so far it seems to be working as it should. All the LEDs light up and all knobs, sliders, and inputs seem functional. There is plenty of crackling when I hit the EQ switches, but hopefully some deoxit on its way in the mail will clear that up. I see on this guy’s page that none of those potentiometers are sealed against dust, so it figures that they’ll be crackly (update: DeoxIT worked wonders, even restoring the right channel which had gotten mighty cracklin). I may also follow his footsteps and swap out the caps in there too as they do wear out with age. This baby’s at least 25 years old. He also notes that maybe ’82 was a little past the golden years for Marantz, but stilllllllll:

    This unit has made a tremendous difference in the sound. As in, major, immediately noticable difference. All the boominess is gone and the treble seems even clearer yet. Those Scan-Speak tweeters sounded awesome before–they are spellbinding now. I’ve been kinda glued to this stereo in the evenings this last week, going back through my playlists, re-listening to favorite tracks, and evaluating the bass on ones that I remember were previously problematic. I’m sort of shocked by the fact that everything now sounds perfect. No more weird notes popping out in the basslines anymore. I had no idea an amp could cause weird EQ issues like that! For what it’s worth, I ran it with any EQ functionality on the Onkyo disabled, and anyway a bass EQ should not cause single-note resonances like that. So STRANGE!! I’m still kind of scratching my head, thinking WTF, that was the AMP causing this, that whole time?! And an Onkyo amp at that?

    So I’ve reached three conclusions:

    1. This Marantz unit rocks. It’s clear. Clean. Detailed. And all of those things at authoritive volume levels. Two nights this week as I laid down to go to sleep I noticed that my ears were ringing! That’s a definite indicator of a quality stereo: one that you keep turning up the volume because it just sounds so good!–until you’ve turned up the volume well beyond a reasonable level and you don’t even realize it because the sound quality remains solid. I definitely fell head first into that trap with the Marantz. Searching around the internet I see plenty of people scoffing at this amp saying that it’s not as good as Marantz’s older stuff.  That may be true, but it’s a giant step up from that Onkyo, and to my ears it sounds excellent.  I’m really impressed with the detail on Telefon Tel Aviv’s “TTV” from Fahrenheit Fair Enough (a reference listening electronic track, to be sure): I had the intro, filled with quiet sonic subtleties, cranked up VERY loud. Unreasonably loud. And when the beat drops, I had my hand resting on the volume control, expecting to need to turn it way down. I didn’t have to. Because:

    2. My bro’s speakers are like 5-10X more badass than I even knew they were. The TTV bassline and kick drum came in at seriously thumping volume, tight and clear, with no distortion or buzzing. That means that those Silver Swan woofers can pump out the volume, and without the bloated notes I was getting from the Onkyo. Oh man. It’s a combination of relief and delight. Turns out I didn’t screw up the design afterall, and not only that, the finished product ended up sounding superlative. These babies can’t top my living room system, but they can nip at its heels. WOW. And as mentioned previously, the Scan-Speak tweeters now sound even richer, more full of detail.  Cymbals sound more present, acoustic guitars seem richer.

    3. I’m suddenly beginning to seriously question if my Aiwa receiver in the living room shouldn’t be replaced. It’s sounded excellent for many years now, but the lion’s share of the credit (and then some) goes to the speakers. I now have an itching curiousity to know what my full-size units would sound like with a better amp supplying the juice. Maybe this weekend I will hook up the Marantz and do some listening.