RobertR

Guess you mean Cabin 10? If there were a Cabin 20, that really would be different... See you soon, wherever. RR

It's model number was MXR-180. If it really was working before storage but now after sitting a long time it pops the fuse, it likely has electrolytic capacitor failure. You'd need a DMM or volt-ohmeter, and a VARIAC would be useful too, to find what is most likely a shorted part. But even then, the other caps in there are equally old, and need renewal at this point, so Kevin's advice is most sensible; he knows those receivers probably better than anybody. It's a lady dog to work on - getting into the folded boards in front will test anybody's vocabulary. However, when it works, this unit is very good - more power than anybody else's at that time, cool running, and a very good tuner as well. But as you have learned, leave the remote unhooked. RobertR

The good news - OTD has opted to join us in Cabin 2 for the first week, so looks like it's all filled up. Deposit has been sent - total is up about $500 over last time, which was 2019; that's the bad news. RR

Once more I have to correct the error - there is no such thing as an MXR2000. You have an MXR-180 model number), commonly called The Receiver 2000. BTW, there is no 'MXR 900', either. Receiver 900, or MXR-90. RR

Many a C-1 has had that problem, and had it fixed with some Deoxit or other such product. Before trying anything else, spray those contacts, then work the switch a bunch of times. If this fixes it, the cure should last for years. RobertR

Welcome b-rider The Manuals and Specsheets section is an ongoing project, and the Carver Receivers section is still pretty new, and undergoing growing pains. Various members are still finding documents, and gradually they get posted. One immediate problem is that the 'MXR' designation is misused in a few places and some editing is needed. This confusion can be blamed largely on the Carver Corp. people at the time – marketing concerns (I guess) caused them to call their model MXR-130, their first receiver, simply “The Carver Receiver”. One looks in vain to find the actual model number on the unit, or in either manual. As Bob tweaked it to make it more powerful, it became the MXR-150, and finally the MXR-180. This last version topped out at 200 wpc (just barely) and was simply called “The Carver Receiver 2000”. There is no such model as an MXR 2000! Same problem occurs in the lower-powered model of that day, the MXR-90. It got marketed as “The Carver Receiver 900” (marketing loves to append a zero!). There is no such model as an MXR-900. And there is no MXR 6250 either! With the Audio/Video models 6200 and 6250 there is no MXR in front of their names. It seems that their actual model numbers were used, a nice improvement, if true. All the factory information I've seen about either model is already on the forum – just the Service manual for the 6200, [and it shows up in the wrong column; hopefully someone with access will fix that]. Doubtless there were some ECO's, SB's, etc. for these AV models, and that literature always uses the actual model number; maybe one day we'll find some, and know for sure. RobertR

magicsam, The Mk2 schematic I have was just submitted to the Forum; it's in the form of digital photos of Sunfire's drafts, and after some needed technical upgrading hopefully it will soon appear in the Sunfire Schematic section, along with a few others I had. The two boards are 653-010 Rev. B-1, and 653-011 Rev. C-3, meaning (as best I can guess) that they are the tenth and eleventh board designs that Sunfire ever produced; they're dated Jan. 1995. Hopefully the same as in the originals. Look on your boards for such numbers as those. The original 2-channel amp, Sunfire's first product, contains boards 653-001, 002, 003, 004, & 005, so you get the idea - 010 & 011 are early. In the True Subs I've fixed, all the electrolytics are usually pretty tired. If you have a cap tester, remove and try a few of the smaller ones. If they are labeled 4.7 at whatever voltage, the capacitance should test at least that high. Among these smaller electrolytics, new ones most always seem to test comfortably over spec. but old well-used ones start to sink below rated value before they crap out completely. One of the symptoms that shows up first is failure to stay on - automatic shutoff takes it back to standby mode right after the bass drum hit that got it to turn on at all. That shutdown circuit cutoff depends not only on the electrolytic that discharges over 10 minutes of no bass signal, but also on other caps that filter the regulated the DC supply that charges it in the first place. I'd strongly advise against trying to out engineer Bob Carver. That circuit is complicated, with lots of safety goodies. Best to leave it as Bob intended. For longevity, again I recommend unplugging it when not using it for any extended period. RR

The Mark II model came out in the mid-90s. If yours is a Mark II it should say so; otherwise probably the earlier model, with larger drivers. I don't have the older schematic, but I suspect it's very similar, and assuming it is, you are going to need more caps than you mentioned. Just 4.7 mf size alone probably number over a dozen, and after two and a half decades they are all ripe for replacement. Many involved in 12 and 13 volt DC supplies. Didn't mean to insult your intelligence about discharging caps, but figure better chancing that than somebody gets floored... RobertR

S/N says 1996 - probably an Original TS model – someone correct me if I'm wrong – never had one that old. Whatever the age, capacitor failure is certainly most likely, as your friend says, in fact it's a near-certainty, but I'd suspect the smaller electrolytics before the two biggest ones. Most of those smaller and mid-sized caps run all the time the unit is plugged in, filtering the low voltage DC supplies, and at this point ought to have been replaced long since. Use 105o types whenever you can get them – they really last longer. BTW, with those big caps, at least one of them stays charged quite a while after unplugging the unit, and it's got enough voltage (AC line voltage x 1.414) to make you wish you hadn't discharged it though your hand or whatever, if you get careless. If you're looking for the power transformer, check outside – it's that big thing that belongs to the electric company. The line voltage goes right to the rectifier diodes. Personally, I keep mine unplugged when not in use. As stated above, those low voltage supply filters never rest when she's plugged in, even though the output stage shuts off automatically. Another known problem, at least in later versions, is faulty/dirty controls, sometimes curable by the right spray cleaner and some repeated turning, end-to-end. Post a few pics if you can figure out how; if not, somebody will help you. RR

Hello magicsam and welcome! There are Truesub schematics, and we have a fair working knowledge of the typical problems that are encountered. There are several different circuits for the various models, so you need to tell us what model you need help with, and give some idea of what the symptoms are. RobertR

"Of all time" covers a lot, including before a single one of us was alive. With that in mind, I'd have to give the nod for the most over-rated (and hyper-hyped) Hollywood contribution to 1939's Gone With The Wind. Selznick's Technicolor fantasy-depiction of the Old South, it tells the story of Scarlett, who starts out as a self-centered brat and nearly four spectacular hours and a surfeit of popcorn later is still a self-centered brat. Gable wouldn't even attempt to sound the least bit Southern, Leslie Howard always turned my stomach, and Olivia deHavilland 's character was so wet you could irrigate Arabia with her. It gets worse - the original showing was in two parts, over two nights, so you had to pay up twice to see the whole gruesome production. RobertR

Hi pindrop - You can run the CF speakers on their original stands next to or in front of your AL3s and use the woofers only, bi-amped, using the original binding posts and fuse, but with the original crossovers bypassed. Maybe just turn the AL3 units sideways 90o so they don't present a big reflective surface, and see how good you can make them sound. With two amps and a DSP you're in business, and if/when you get back to the ribbons nothing is destroyed. I can send you some dsp settings that will get you started with pretty good sound; final tweaking for great sound is up to you - rooms, and locations within any room, are quite variable. If you want make it permanent, remove the ribbon and the entire vertical structure that holds it (leaves about 20 little screw-holes per channel), and then you can do as I have done and mount the little speakers on top of the woofer enclosure. The stands consist of your original flanges at the top end - two shortened uprights, length 23'' (that's two feet shorter if you want the CF speakers at the same height as now) - plus a pair of custom flanges about 4''x4'' at the bottom, bolted through new holes in the top of the woofer cabinet into four T-nuts you add inside the box. Speaker wire feeds from existing binding posts on the back plate, through the fuse (if you choose to use one), and bypassing the AL3 crossover, going right up through the upright support in the usual way to the little XLR plug for the speaker on top, where you use the original flange. Alex Sauter made mine for me, and I'm guessing he'd do more for others, at a reasonable price. You'll need the upright, cut to the right length and tapped; the bottom flange, drilled; and the flange mounting hardware bolts and T-nuts. You could have him get it powder coated for you if you like; I didn't bother. Or, you could shorten and re-tap you old upright yourself, and then cut the original floor base plate down to use as your mounting flange. Obviously those stands are now history- you can never use them again in their original configuration. The black (plastic over MDF) woofer cabinet could be finished a number of ways, anything from stick-on tape to rosewood veneer. Or just leave it ugly, like mine... RR

Oh yeah. Using a mini dsp with them, and that's what got me messing around with listening to various frequencies, looking for problems and trying solutions. RobertR

PMAT - I hope you try the plastic bag trick. It's so easy - just two Allen screws and the speaker is off the column. Tape or tie the wires so they can't slip down out of reach (if yours have the rear binding post option, no need). Then slide some bags in there – no need to tamp them in tightly; they just need to touch the walls at a number of places, all along. Now remount the speaker, take a knuckle or something and bang on the side of the support, near its center, and note the sound. Now bang on the other, unmodified channel. I'm betting you will notice quite a difference. If you're living in a state where single-use plastic bags are banned and therefore aren't so handy, many other things would work just as well – smaller-gauge bubble wrap loosely wadded up, for example. A small bonus is that when you take the speaker apart now, the wire is quite unlikely to slip down inside the support. And that wire can never vibrate in there, either. I hope somebody figures out the resonance frequency of the stock 47'' uprights – I'd do it in a minute, but my own full-height ones are many miles away at present. RR

Part 3 Now to cover specifics for this pair of Sonorous. A nasty sound in the neighborhood of 300 Hz could be a leaky end cap – you can find that by ear, or even by feeling the draft, when the tone is playing fairly loud. Travis sealed this pair very well, so I heard none of that. But there was a nasty buzzing evident, mostly in the right channel, though if I cranked things up and listened for it there was some in the left as well - midway between 164 and 172 Hz. Turns out to be nothing in the room; it's from the speaker itself. Sounds like a bad side-driver, but on examination it's not – surrounds all good, no voice coil rubbing, and it's not loose driver-mounting screw. Besides, the rotten sound is the same from all four. Suspecting that it's maybe a wire hitting against the back of a cone, I finally pulled out the tweeter and got right in there, but the wires are in no danger of hitting anything live. It turns out to be caused by sympathetic vibration of the power resistors in the crossover! There are five resistors in there and, being all the same physical size, they all vibrate at about the same frequency, sounding like a hornets' nest. Particularly if they are mounted slightly elevated off the board, at a certain volume they would scream their version of harmonic distortion whenever somebody hits the E below Middle C. The channel I had that was producing more of this garbage turned out to have its resistors mounted clearly looser, above the board (or above the coil in the case of the middle one). My solution was to dismount the speaker, lay it on its back, and with the tweeter and the central wad of fiber-fill removed, dab some flowable silicone sealer below, beside, and between those resistors – enough to render them virtually motionless. I used the thin stuff because it's easier to get some of it underneath things with little clearance. I used Windshield Sealer -VersaChem 75009 (from O'Reilly's; other auto stores sell Permatex 81730). If you do this trick, avoid coating the tops of the resistors too heavily, as they need to be able to dissipate heat, though I must add that the wattage spec of these resistors is far into the overkill range – they rarely get even slightly warm (recall that the famous torture experiment at the 2015 Fest, which sautéed the side-drivers, did no harm to the crossovers). A non-magnetic tool is almost mandatory for accurately applying this stuff among all those magnets. Wood works fine – I used a Popsicle stick; a throwaway chopstick would do the job as well. I also glued the circuit board edges on two edges, just for luck. The vibration in there is amazing. Did both channels the same way, of course, and let the silicone set a few hours, then replaced the fiber- fill and the ribbons. All done and seemingly ready to test, except there was another trick to play before remounting the speaker... Louder frequency glide testing had disclosed another problem, centered sharply at 325 Hz, at which point the upright supports in my custom setup do a lot of sympathetic vibrating, producing some quite audible buzzing – pretty nasty. [Note: my custom uprights are just 20” long, as they're attached atop two-foot high (AL3) woofers, and sit just six feet from my ears; the stock supports are 47'', and would therefore doubtless resonate at a different frequency.] Anyhow, the cure was to take a long-enough dowel (could have used a yardstick) and use it to shove some everyday empty plastic grocery bags into the column, to damp it. I used just 3, but the much longer originals would want maybe 7 or 8. Obviously you want to have the feed-through wire held in place before stuffing the bags in there. Anyhow, this trick tamed that resonance down to where it's no longer audible. Kind of Mickey-Mouse, but it works, and you'll likely never see it again. [Be sure to use audiophile-grade bags, though - none of that Walmart crap!] I put it all back together* and I revamped my response curve a bit, so now it's a bit flatter and simpler, for not having to reduce the gain at and around those lower midrange frequencies that sounded offensive before. At this point I have no hesitation is stating that the CF speakers sound cleaner than any of my seven pairs of 48'' ribbons. And the sound-stage produced in my trinaural LR setup with three of these little wonders is unbelievably, staggeringly huge. It's kind of mind-boggling how such small speakers can create this immense acoustic envelope, and then sort of vanish into it. Now that I have both systems running with AL3 woofers plus subs to augment just the bottom octave, they are truly full-range, four-way reproducers. There is a further advantage to these speakers over Amazings, and the older I get the more I appreciate it – one can lift these more easily, and by removing a pair of screws in each channel the load can easily be divided into two pieces. The CF speakers are not overly efficient, and, as has been observed by many, in a good-sized room a pretty powerful amp makes a noticeable improvement with them. Thus for example a TFM-45 is clearly preferable to a TFM-15. And I mean 'clearly' in a couple of senses... RobertR *Be sure you have the four little rubber feet between the bottom end cap of the speaker and the top of the mounting flange that it sits on. There is a lot of vibration, and they help quite a bit.

Sauters were big help in the physical mounting of the little CF speakers on top of AL3 woofer cabinets. Since that I'm on my own. I have the results page just about finished, discussing a couple of problems and how to deal with them. But no rush to post - I'm hoping those interested will find time to get into some 'room-debuzzing' sweeps, and note any frequencies where they hear problems from the speakers, not the room. RR

Part 2 Back to the Carverfest speaker mod, but first I should take a minute (a page, actually) and mention that everyone should do some frequency glide testing. You will discover little problems, sometimes easily solved, that degrade the overall sound of your system. If you don't have a sine-wave generator, just feed your laptop audio output into an AUX input, get on line and go to any of a number of free sites, the type that lets you change the frequency in a continuous sweep, with a mouse-drag or whatever. The one I used is Synalski (their default output level is 75% - I find that just 5% is better). Set things up so that you are in control at your usual listening position. First, do one channel at a time, and then repeat with both channels together. At a fairly high level, sweep at a moderate rate from as high as 2-3 KHz right down to the low bass; you will want to reduce the frequency more and more slowly as the frequency gets lower. Listen for increases or decreases in response – you will likely hear plenty of them. But also listen to the quality of the sine wave tone. If it gets to sounding 'buzzy' at some frequency, that's maybe distortion in the speaker. Or perhaps a resonance in the room - those can be anything – a lamp, a picture on the wall, a wooden side panel in a chest of drawers, or something in one of its drawers. Maybe some loose object on a table, or a storm window, curtain rod, or even the cover on your amplifier – everything has a resonance frequency, where it will vibrate, and if it's not somehow damped, you may well hear it. Might have to make the tone louder to help run down the offending gremlin, as you may suddenly not hear it when you change your location -but keep hunting – it's there, at your sweet spot. If you can hear it now in this test, you hear it during louder music playback as well, but likely won't identify it, buried as it is within the complexity of the music. It will add to the sound, but almost certainly subtract from your listening enjoyment. Some of the response dips you will hear are caused by the two speakers working against each other, right in the area of your listening. If you cut off one channel (or reverse the phase of just one speaker) and the sound gets louder, that is the case. This is a problem of room acoustics, not part of this discussion, but maybe solvable with a well-placed tuned trap. Also, at some frequencies there may be a peak or a dip just where you sit even if just one channel is playing. Peaks can be reduced with a notch filter, but dips – no so easy. If you move and the dip disappears (tone gets a lot louder), again, that's a room problem. Anyway, I always do this sort of testing, and the current speaker project was no exception. I found a few room noises, plus a couple of fixable things that were emanating from the speakers themselves, and may well be emanating from yours, as well. But today is a holiday for most, so I'll finish this post in another day or two. Meanwhile if you get a few minutes give the room de-buzzing sweep a try, and take a few notes on what you find. RR

Afraid I'm without a camera at the moment - mine got stolen, along with my whole carry-on, when changing flights a year ago. Keep thinking to get a new one, but don't know what to get, and shekels are a bit short... RR

At the end of the 2017 Fest, Kevin gave me a pair of stripped AL-3 woofer cabinets he was through with. I installed a pair of spare drivers I had, one used, one unused. Some months later Alex Sauter made me a pair of rear plates, to seal up the back, and we installed two pairs of speaker binding posts, but no crossovers or fuses. Then he cut several lengths of the original-type aluminum stock for upright supports. The original Sonorous Speaker stands use 47'' uprights, but these new ones are to be mounted atop the woofer cabinets, which are 24'' high, and listened to from my bed, with a somewhat lower head height than a normal chair. I was provided with lengths of 18, 20, and 22 inches; the 20'' turned out to be perfect. Also provided were new flanges for mounting to the woofer enclosures, into which Alex installed T-nuts for four machine screws. Pretty rugged, but I won't use it as a lifting handle. Skip ahead to the 2018 Fest, where I took the woofers and Travis sold me a pair of CF speakers, so now I could complete this experimental project without poaching a pair from my living room three-channel system. But when I fired it up system it became evident that the older woofer was in need of a new surround. Just like magic, Harry produced one and installed it, like new. (Speaking of Harry, I should mention that the concept of bolting a CF speakers atop woofers was his idea, a year earlier.) Travis had hard-wired the speakers to the feed wire that comes up through the stands, but for portability I wanted to restore the original-type plugs, so I did so. Then came some testing, and into an interesting learning curve. It was a no-brainer to opt to use a MINI dsp 2x4 for integrating these units. The basic $100 model with the parametric (“advanced”) software. Three things for the dsp to do: -Split the signal (crossover). This is easy, though I used the trick of setting the crossover-point a lot lower that -6dB, simply because I wanted a response cut in that area of frequency (turned out to be around 155Hz). -Balance woofers to top unit. The CF units retain their original passive network, and have good deal less sensitivity than AL3 woofers running straight out of a power amp, so they need to be turned down a bit. I always have found that getting the right amount of bass is the easiest part of voicing a speaker system. [Good thing, too, because any change in speaker or listener position screws it all up.] -Voicing/EQ-ing – Easier than for bi-amped AL3s, because, again, the CF speakers retain their original passive voicing. But still a fussy bit of tweaking, done over the course at least a month. This cheap Mini DSP is great – for the money nothing I know of can touch it – but there is a problem getting enough gain out of it without clipping the input (YUK!). Lots of playing with shelf filters before it's at its best. Each time I started over, some aspect sounded better. I have to pause here – other things to do – more on this later. RobertR

The guy needs to measure the dimensions again...

Ray - Have you tried them about half that far apart, but with SH? Huge! RobertR

Those cabinets were from the factory, and not uncommon. Remember, that model was the best selling Phase Linear model ever. The drawback with the PL1000 wasn't looks, it was that it had unusual dimensions, and thus didn't stack well with all the usual 19" stuff. The wooden case just makes that problem a bit worse.

You'll want a low pass filter, not a high pass! Just for fun, you might try using your amp in it's stereo configuration, and run one driver with left and the other with right channel information. Sometimes a bass instrument is recorded well to one side, and that can result a balance problem with a single channel hookup. RobertR

I'm guessing any SS amp. My first experience with this was with my homemade.power amp in the early '60s. Class B, though at the time I didn't know B from sausage.. Couldn't believe how hot it got running 10KHz - I thought just bass tested an amp. This was as far from Bob's amps as you can get - low power, and Germanium transistors - something that anyone who missed them because they were born too late should be grateful for. My brother, who was studying to become an EE, wised me up, same as Bob - "just don't do it." RR

fill wrote: Has anybody blown up an A-500/760x by feeding her high level/high freq tones? fill - I have no way of knowing that. I certainly haven't in any of mine, but then I'm not going to come even close to finding out. I do know that it happens to amps, and that a lot of guys are surprised when they first encounter it. We blew up a Lightstar that way a couple of years ago at the Fest. My cautions were dismissed then, too. I don't remember exactly how much power it was cranked up to, but as best I recall it was around 60%, at 10 KHz, into a pure resistive load..And of course that's a tracking power supply. .It was gone in mere seconds Bob heard about it afterward and said it was sure to happen - you just can't test SS amps in that way. Anyway, not looking for an argument - just want to be sure the guy with speaker troubles doesn't add amplifier troubles to the mix. RobertR