What a wonderful collection of beautiful, unique pieces. Would love to see some interior shots if you have them! The green hammertone is particularly fetching. For a moment there I thought you had sprayed your play counter with it as well.
Done tuning DC offsets (blue) of this phono preamp over a variety of op-amps...no coupling or chopping needed. Final response 20-20k is the last two plots. Has about 1/2 of "Neumann 4th pole" EQ to take over above cartridge loading's resonance. I started a new design, after plugging away at phono ideas for a while; no capacitor higher than 100nF to facilitate SMT PP, subsonic filtering -30dB at 9Hz. All E6 series resistors and caps from the bin. Running rail-to-rail at 0.08% THD. With the other optimizations, might be one seriously quiet MM when TI gets my chips back in stock... That mid-stage sub-bass hump: also a more efficient crossfeed for side-channel rumble killer.
Same here! Saw them at Bogarts in Cincinnati sometime 91 or so. If I recall they opened for 7 seconds.
Ahh a man of wealth and taste. I'm not a Freecell guy, but I am a Spider Solitaire guy and play the same Microsoft game suite. I'm at level 64 on Spider.
And just to finish off this little project, below with the new 10" alumina ceramic arm wand in action, playing the incredible side 2 of one of my all time favorites, David Bowie Low. This the nice sounding 1980 RCA International master cut by Denis Blackham (Bilbo) at Tape One in London, think I have the whole series, they sound great but they skimped on the covers a bit (no gatefolds) since it was a lower cost series...
Yea, mastering is great on that series but wish the pressings were just a little better. Early 80s was kind of like now in some ways, quality often wasn't very good, my copy of Low isn't centered very well and not the quietest vinyl. Wanted to make a sample recording with the new arm wand, so what else, "Subterraneans" it is Dropbox - bowie_subterraneans.flac - Simplify your life
While on the subject of alumina (aluminum oxide) derived tonearms, like my alumina ceramic one above, Kuzma has now introduced a new flagship arm with tubing made from another type of aluminum oxide, sapphire. It's part of the corundum family of aluminum oxides, and with similar properties, but generally a little harder, and a lot more expensive than common alumina ceramic. They are using a pretty big diameter tube for extra stiffness, not sure what wall thickness it is, but they list effective mass at 60 grams! Wow, that's a pretty hefty tonearm mass, and surprisingly they list compatible cartridges as 25cu and less, but they also say 5-7Hz resonance is the preferable range. Even with my arm and a 25cu cartridge like the AT-OC9XML, I'm down in that range. I really designed it for a lower compliance cartridge, like my Benz Micro, but it still works fine with around a 6Hz resonance. Oh yea, and the Kuzma arm costs 20,000 euros
I saw that arm on another site, where they alluded to, but didn't mention the actual price. How does 60g compare to the linear trackers? I know some have quite high horizontal masses due to the weight of the trolley.
The ones with a trolley are generally servo controlled, so the arm pivots a small amount at the trolley, which is moved via a sensor and motor. So the arm isn't directly seeing the effects of the trolley inertia, only its own inertia as a short pivoted arm, it is decoupled, and the servo system is handling the trolley. But the air bearing arms do have to contend with a larger lateral inertia, so the arms are generally very lightweight and the part of the air manifold attached to the arm is also lightweight. Still, most of them will have some degree of cantilever movement on off-center records, especially with the more compliant cartridges.
I completed the latest of many DIY room acoustic treatment projects this past week. While I designed this latest project in it's entirety, I should mention that I had professional assistance with several of the elements which were beyond my skillset.
Today's project is upgrading the crossovers in my Monitor Audio Gold 100 speakers. I originally replaced the capacitors with some better ones I had on hand, but have wanted to do it right for a long time, and now is that time. Replacing the 4 capacitors, 3 resistors, and one coil. The new capacitors are WEET aluminum foil and polypropylene capacitors, replacing what were originally three Bennic-type metallized polypropylene, and one polyester capacitors. All the cement resistors are replaced with Mills MRA12 wirewound, and the woofer iron-core inductor replaced with a much heavier gauge air core with about the same resistance. Three of the capacitors and one resistor are relocated to the bottom of the PC board since there isn't room on top... Original ...
How are the first impressions? No pics but yesterday I swapped the RIAA caps on my phono preamp back to the originally supplied cheap green polyesters, from the upgraded PP. Perhaps the PP I had used were inappropriate for my application, but the Mylar caps sound better/smoother to my ears. Most every change I've made to the preamp has been undone. About the only change I've kept, is replacing the input and output coupling caps with the correct values per the silk screen (to fix the bass roll-off issue created by value substitutions made by the manufacturer). The guys @ Techtalk (Parts Express) that seem to know crossovers don't like Mylar caps in crossovers, some of them use pretty expensive PP caps.
Just a question or two. Your construction looks second to none, I am just wondering, with that huge obviously worthy woofer, what would have happend if you had exceeded the 1 cu ft box? I assume you are going to pack it well with acoustic material, as we are always told, with some good packing the driver sees a "larger" box! I'm just curious what would have happened sonically, if you had opted for a bit larger box???
To be completely honest I'm not sure what would the effect would be. This is the suggested size for best sound quality. I got it mounted up this weekend and was simply amazed at how great it sounds. It's definitely not a one note home theater sub. A very flat response.
First impression is very good, some delicate shimmer in the cymbals comes through that wasn't obviously missing before, the sound seems better integrated overall, I only have one speaker upgraded right now so that I can compare old to new, and letting the new one get a little play time, then I'll more seriously compare, and if all seems OK, do the other one. So may be a couple days before I finish both. What cap values are you using in the phono preamp, is that the TC-750 with 3300pF and 12000pF? Capacitors are kind of a complex subject, but even moreso in speaker crossover applications. Probably too big a subject to get into here, you have to look at them as more an electro-mechanical element, and there is solid engineering behind many of the better audio capacitors. But the better foil ones can get expensive fast, so probably not a good upgrade for common speakers. My speakers are a little above "common", but kind of borderline in deciding if the upgrade cost is worth it. I'm really attached to their sound at this point, so that puts it over the line for me, and worth the upgrade, though cost would've been too much had I not gone with the WEET capacitors. The ones I used are the WMH series, which are aluminum foil and polypropylene film capacitors, and made to compete directly with the highly regarded Jantzen Audio Alumen Z 100V capacitor, almost the exact same dimensions, but at a much lower cost. Jantzen Audio is in Denmark, though I think production is in Poland. In any case, they are EU products and have gotten very expensive in recent times, especially at places in the US like Parts Express you mentioned. The WEET caps aren't available through distributors yet so I went through their sales team in China to get the ones I needed. I'll followup on my DIY post above when both speakers are done and settled in
Yep, the TC-750 w/ the 3300pf and 12000pf caps. I think the KEMET capacitors I tried sounded a little grainy (maybe even harsh sometimes) compared to the original polyester caps. It took hours and hours of listening, but over a wide-variety of material, the crappy green ones won. I very closely matched the values, but perhaps the series of KEMET I used wasn't ideal for RIAA. I predict you'll hear even more improvement once you have both speakers upgraded. Let us know.
What type of KEMET capacitors did you try, they make a lot? Surprised you noticed so much difference, were they the exact same marked values? Maybe off in tolerance? Anyway, that is a location that will tend to amplify differences, and nothing wrong with liking the stock ones more. I tend to prefer the tightly wound film and foil caps in the cylindrical axial lead style over the flattened radial type, they seem to have more clarity and transparency, but hard to generalize, there are always exceptions, and polyester caps can sound great too in some form factors. For instance, I'm a fan of the ERO MKT1813 metallized polyester caps, they can sound great, very tightly wrapped cylindrical package, they are part of Vishay nowadays. But for RIAA caps, I'd always go with the best reasonably priced polystyrene film and foil caps I can find, especially if you can find some tin foil types (I know we've talked about this before). Anyway, cool that you were able to settle on the ones you like and not worry about it anymore Sounding pretty good, been playing the Melanie De Biasio Blackened Cities over and over, love this record, can listen all day ...
Yeah there are probably capacitors more suitable to RIAA circuits. I used the PHE426: https://content.kemet.com/datasheets/F3294_PHE426.pdf I ordered ten of each and selected the two closest to the measured values of the originals. Not perfect, still a couple percentage points off (IIRC). But the difference I hear is in violins. Outstanding recordings still sounded outstanding with the KEMET (but no better). Marginal recordings start to sound harsh/shrill, I have recordings I just didn't enjoy with the KEMET caps but which sound nice with the stock caps.
Yea, I moved both speakers next to each other in the center, and then mixed one of my favorite songs from the Melanie De Biasio No Deal album down to mono, then played the file and set balance to either left (upgraded) or right (original), and the differences were pretty big. The left side sounds more like it is in stereo, more depth with natural ambient cues, more height sensation, instruments and vocals in their own space, whereas the right is a flatter sound, everything gets a little bunched up, it's a lot more obvious that only a single speaker is playing. Anyway, gonna do the other speaker now, very much an improvement, don't really hear any downsides. Overall tonal balance seems about the same, just a more open and inviting sound with the changes. Pretty happy with the results.
I found all of that to hold true when I was working on a crossover network for my open baffles. Starting with inexpensive capacitors for some of the initial listening test proved to be a double edged sword as I could easily tell they were robbing my drivers if the dynamics and transparency they were more than capable of.
Yea, I've made a few crossovers in the past, though not with capacitors of this quality, generally just with decent sounding metallized polypropylene types, and maybe something more special on the tweeter. I just checked the current pricing of Jantzen Audio Alumen Z-Caps at Parts-Express, which should be a close equivalent to the WEET WMH caps I used, and the price is about $600 to do the pair of speakers, and that's without shipping and tax. They've gone up a lot in recent times, when I checked pricing in the past I could almost justify the cost, but that would be way too much now to dump into these speakers. The WEET caps were $146 total, and then another $60 to FedEx them from China, so that made it worthwhile. Add six Mills resistors and a couple big gauge air core inductors, and all set for under $300 upgrade cost. For a large manufacturer, I can understand not wanting to put much extra money in the crossover, it's hidden and most people don't appreciate how much difference it can make using better quality parts. But some manufacturers don't even use better parts on their very expensive top models, sometimes I wonder if they have evaluated the difference between crossover components, or just assume that it couldn't make much difference. I know we tend to exaggerate differences between components, we all have our own audio priorities and value some aspects of the sound differently, but like you said, it does leave a lot of performance on the drawing board when you don't optimize the crossover components.
