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Super 12 Tweaksfor the Hammer Dynamics loudspeakersGeneral InformationBy TweakBy ContributorNotes from the Full Range Driver ForumOther Links
These tweaks represent a work-in-progress. Some tweaks will work better than others, some are outdated. You should read all this page and determine what might work best in your situation. No information is guaranteed to work as described or at all! Use your best judgement. Pictures of Super 12sSome pictures can be expanded to full size by clicking on them. James's semi-gloss black 
Tim Adam's 
Mick Wolfe's 
Bob Hedberg's birch ply 
Stephen's quarter stripe mahogany 
Lee Hankins' beautiful Super 12s 
Super 12 DriverThe Thiele-Small parameters for the current Super 12 driver are Fs 46 Hz, Qts 0.38, Vas 112 liters. However, the Hammer Dynamics box design is nothing like the parameters would suggest. Editor's note: the current Super 12 box has a volume of approximately 7858 cubic inches or 129 litres (not counting reduction in volume from damping materials). A typical vented box alignment suggests a volume of 93 litres. John Wyckoff's description of the Super 12 (compared to the Eminence Beta-12LT)Cone composition: Beta-12LT is conventional Kraft type. Super 12 is slightly heavier (different mix of fibers). Voice coil: Super 12 has smaller gauge wire with a Nomex former. (I dropped the Kapton former after the first ten samples.) Beta-12LT uses Kapton former which is not quite as neutral in the mids. Super 12 coil is slightly lighter bringing moving mass to about the same. Super 12 uses one shorted voice coil turn to reduce inductance and improve high frequency response. Motor: Super 12 has a soft-iron polepiece to improve BL. Beta-12LT has low carbon steel. Super 12 has shorting ring at the base of the polepiece and is capped with an aluminum shorting ring (also called Faraday ring). Spider and suspension: Super 12 spider is woven Kapton fiber and is slightly softer. The suspension on the Super 12 is doped to be slightly stiffer. Glue: Super 12 uses a lower-mass, harder formulation, and less of it. Improves high frequency response. Driver ModificationsDo not touch or mess with the cone! Damp the steel basket using Moritite rope caulk. Press it firmly onto the legs of the basket and wrap it around the legs/magnet connection. Do not cover the vent hole on the rear of the magnet. Put pieces of Deflex (or carpet felt underlay using double sided tape) on the inside of the basket legs (facing the cone) to absorb cone rearward reflections. David Bardes wrote:
Remember to break-in your drivers thoroughly. John suggested blasting classical music (loud noisy stuff) with a solid state amplifier. Cover your speakers with blankets (don't hit the cone or tweeter) or run them while you are at work. Like other full-range drivers, the Super 12s take a long time to break in, probably at least 200 hours. They will take forever to break-in if you use a little one or two Watt tube amp and play at reasonable listening levels ! SupertweeterThe original kit contained a titanium dome Audax supertweeter. The current kit contains a fabric dome Audax supertweeter. User comments imply that the original titanium dome is somehow clearer, more extended, or more metallic and harsh, while the new fabric tweeter is softer and smoother. Some users appear to prefer one, some the other. Tim Adams has tried a Fostex tweeter, the Fostex FT17H, available from Madisound. Price $35 each. 
Now several other people including Michael Greene have tried it and all fully endorse this tweeter. "At Larry's suggestion, I ordered the Fostex FT17H tweeters for the Hammers and have just in the last couple of days, had a chance to hook them up. I have to say that if anything, these tweeters are under-hyped. I haven't heard much mention of how pretty they sound. This is the most unfatiguing yet extended treble I've ever heard—and that w/o much break-in. (Noting that I hate sizzle or exaggerated treble.) I am using a pretty good sounding (better than the original Benninc 1.7uF) 2uF mylar cap that Madisound is currently offering on its sale page bypassed with a 0.22uf Westcap--used more to get to 2.2uf for the crossover point than for tone. The x-over is first order on the tweeter. I still find that I get a little fuller sounding upper-bass with the original x-over configuration on the 12". I can now see how this mod (removing the last inductor on the 12") would be amp and room dependent. I tried the Fostex's on the original tweeter crossover too, but find that the first order still sounds better. Despite the efficiency match, I found that padding the FT17 down ~1dB made the treble integrate better with the 12" (although this could change with more break-in) Initially, the treble could be heard to be coming from the tweeter. After padding, the highs appear to originate from the instruments on the soundstage and thus the speakers disappear more. I used a "fixed" L pad of 1R shunted by 65R. Found a pretty convenient L-pad calculator at: http://www.eatel.net/~amptech/elecdisc/lpad.htm. If anyone disagrees with the numbers this thing spits out, please let me know. " - Michael. See Michael's current crossover mods below. These tweeters need some kind of mounting system. They are too big to go in front of the Super 12 driver. Tim mounts them on top and pointing down at the listening position. CrossoverSee new notes in the Discussion (below). 
These are Dick Olsher's values and the Hammer Dynamics kit contains slightly different values. I have heard that upgraded capacitors and resistors, especially in the tweeter network, helps a lot with removing any trace of harshness. Well, now the Zobel needs to be improved too (see Tim below). And the inductors. Actually, changing everything for higher quality parts is worthwhile. Don't forget to read the notes in the Discussion area. Michael Greene's current crossover with Fostex FT17H horn tweeter: 
Box ConstructionBracing of the cabinet is useful. Several options are helpful. One option is a simple stick brace running from the front panel just below the Super 12 driver to the back corner of the cabinet. This controls resonance of the front panel. However, it does not help control vibration in the side or rear panels. Another option is to make a "window" brace, which is a square of wood (MDF) with four squares cut out leaving a cross in the middle (looks like a window with four panes). This is fitted just below the Super 12 driver and is glued and fastened to the front and sides of the cabinet, and the rear panel screws to it. You might want to round off the inside of the windows with a router with round-over bit. A third option is to run lateral braces down the side walls and front and rear baffle (making them stiffer). Do not make a brace from the rear cabinet baffle to the driver magnet. According to John Wyckoff, this will simply transfer cabinet vibrations to the basket structure of the driver, messing with the sound. A stiff and damped driver basket is preferable. By Michael Greene:
Important note: the manual mentions using "drywall" screws. These have a fine thread and are not suitable for using in MDF. You should use "deck" screws with the coarse thread if you are building with MDF. Remember to build the cabinet with a removable back baffle if at all possible. It is very useful to be able to get inside and change stuffing / dampening materials at a later time. The manual describes building the box using "strips" of wood on the internal panels. These strips are simply to locate the edges properly so you get a reinforced joint (not a pure "butt" joint). John felt it was easier for an inexperienced woodworker to make these strips and build the cabinet this way. An alternative is to use a router (or similar power tool) and cut rabbets in the edges, making rabbeted joints. I would definitely encourage you to investigate this alternative. Ask woodworkers and cabinet makers for their advice. If necessary, consider renting a router for the day just to make the rabbets. I believe this would be easier, quicker, and make more accurate joints than the "strip" method. In both cases however, you need panels that are very accurately cut to size. If possible, you might want to get a professional cabinet maker to do just the panel cutting for you. The accuracy here really helps you out later on. Look into woodworkers forums for help and inspiration. If anyone tries building different types of enclosures or volumes, I would like to hear from them. Box VolumeThe current Super 12 box has a volume of approximately 7858 cubic inches or 129 litres (not counting reduction in volume from damping materials). You will probably want to keep to approximately that volume. The dimensions are also important, internal cross section is 13 x 13 inches (330 x 330 mm) and internal length is 46.5 inches (1180 mm). The reason is that the enclosure acts as a tuned pipe, resonating at about 500 Hz. This is supposed to compliment the driver and is part of John's design. Damping & StuffingIt looks like there is an improvement using Deflex panels (the large subwoofer 300 mm circular size) behind the driver. An old suggestion was to hang a 1/2 inch thick piece of carpet felt underlay so it drapes down behind the Super 12 driver, but the Deflex subwoofer panel is better. Room PositioningHere is a quote from John regarding room placement of the S12's. " I try to keep the S-12 on a 60 degree triangle with the listener at the peak. In other words: If the speakers are 6' apart (inside of cabinet to inside of cabinet) your head should be about 8' from the baffles. Toe-in should have the center of the drivers crossing a foot, or so in front of your head. Your results may vary, but this has been a good starting point for most owners. Remember, it's the 60 degrees that's important, not making sure the triangle is 6' x 8' " (James) I have found that pulling the speakers well away from the back walls helps a lot. My room has a very "live" end near the speakers, and this increases the bass output to the point where it tends to overwhelm the midrange. Bringing the speakers about 8 feet away from the rear walls, and 3 feet from the sides helps. Curtains and drapes over the windows (which are between my speakers) also helps. I have tried different toe-in positions. Facing straight at the ears is the most dynamic, but I get best results (slightly smoother sound and good imaging) with a little more toe in. The speakers cross about 1 to 2 feet in front of the listening position. The speakers are about 10 or 11 feet from the listening position. I would like to try a Behringer Ultracurve equalizer which should remove the worst room interactions. Update: (James) I have bought a dbx Driverack 260 and it has improved the sound of the Super 12s. (I am still using stock crossover and original titanium tweeter). The sound was "dark, closed in", and using equalization, the highs and upper mids are lifted, while various resonances are removed. The auto equalization is a bit agressive, but after auto EQ, I manually reduce the highs and mids, keeping the lower resonance changes. Speaker CablesJames's current speaker cables are 20 gauge Litz design from John Wyckoff used on the Super12s. They use 30 gauge silver-plated copper solid-core wire with Tefzel insulation, part number V1090-ND ( white ) from Digikey ( blue V1091-ND, orange V1092-ND, and yellow V1093-ND also available ). Price is about $20 per roll of 200 feet. Just take 10 lengths of 30 gauge wire ( put two nails in a board at the distance required for your cable length, then tie your wire to one end, then go down to the other end and back the required number of times - 10 strands total) and twist them together in an electric drill. I twisted them to about 3 turns per inch, then backed off ( reversed ) the drill to about 2 turns per inch, this prevents the cable unwinding violently! Now strip and solder the ends together. Two of these go to the wide range Super 12 drivers (i.e. 20 strands total, 10 for positive, 10 for negative). Now take 4 lengths and twist them together; two of these go to the tweeter (i.e. 8 strands total). Notes from John Wyckoff(Brad wrote): Hi John, I got the kit...and sent you the $25 for shipping. Some questions:
(John replied): >>>I use solid core 20 ga. silver plate copper with teflon to the woofer and 3 strands of 30 ga. tefzel wire-wrap wire per polarity to the tweeter. The stuff you mention will probably be OK, but I do prefer the solid core.
>>>There is no port tube in this design. It is tuned to the port being the 3/4" thickness of the baffle. I can recalculate for you if you want to go 1.5" on the baffle.
>>>See above
>>>Adhesive backed asphalt sound deadening panels are good. Carpet felt is good. But really you'll have to tune this to your liking.
>>>I have just started recommending a threaded-rod brace which mounts in the center of the baffle to the center of the back, two inches below the driver. I used 5/16" threaded-rod with O-rings, then washers then nuts, and lock nuts. Hand tighten only.
>>>The asphalt sheet, under the bubble wrap. It is available through Parts Express. 10" tiles are part# 268-010, they are $0.88 each. Use about 4 four per side and back, one on the top, and as many as will fit on the baffle. Also carpet felt glued to the inside of the struts on the driver chassis. Tim AdamsFor the best sound the tweeter must be aligned with the baffle in both planes and focused on the listening position. So far I used a Deflex Power Pads ($35.50 ea. from parts express) directly behind the driver and on top of the asphalt based material (bubble wrap removed). They are thicker than the panels. I still am using the asphalt based material and bubble wrap on the rest of the interior. Additionally I still have felt on the sides. I intend to use some Deflex on the sides and top soon. It is superior to the felt by a good margin… Upon further experimentation I have concluded that the Deflex is indeed FAR superior to the felt curtain, and should be used in lieu of rather than in addition to the felt. To use both — as John wanted me to try — robs the super12 of some midrange magic. I have made a real breakthrough with the controlling the backwave and also the basket resonance — Mortite. I used 5 lbs (total) in the cabinets. I completely covered the back of the basket and magnet on the drivers. Then I ROUNDED all corners of the upper half of the cabinet with the Mortite… Wow ! Vast improvement to an already great sounding speaker. Improved the clarity, upper frequency response, bass, the image is much wider and deeper. Hard to believe for such a simple tweak. Cheap too ($20). I replaced the notch filter components in each channel with the following: One 8 µF 100v Hovland Musicap bypassed by One 0.47µF 400v Hovland Musicap in parallel I am now using Northcreek wirewound resistors in both the Notch and the Zobel. A 10 ohm and a 50 ohm paralleled in the notch. I recently made a rather surprising discovery… It is very important to upgrade the parts quality of the Zobel. I replaces the 10 µF cap with a polypropylene one. An 8 ohm and 50 ohm Northcreek wirewound paralleled in the zobel. The sound is wonderful, very transparent. The upgrade is worth every penny. Bypassing the Caps in the tweeter network with .01 µF Teflon caps smoothes things out nicely too. I just installed a 10 ga Solen Hyperliz inductor in the 0.65 H notch filter (remove 1 turn from a stock .68), and replaced the other two (.3 H and .24 H) with 14 ga hyperlitz. By far the biggest single improvement I have ever made. The clarity is now astounding. Mick WolfeWhen I first began the Hammer Dynamics project, I encountered a few people ( including John Wyckoff ) who felt thin gauge solid core speaker wire usually created a good synergetic match with the Hammer. I experimented with a few different wires upon completion of the Hammer and its all important break-in period. My favorite going in was the Harmonic Tech Pro 11,but I've since found it a bit thick and overly warm with the Super 12.The edge and bite of the real thing was either missing or too "rounded". I turned then to a simpler , less expensive " thin" solid core. My choice (mostly on a whim and because I'm a tightwad at heart) was the Mapleshade Single Helix. This will run you all of about $85 for an 8 foot pair. My initial listening sessions with this wire were promising enough that I went ahead and ordered their outrageously expensive $65 Single Helix interconnect. To make a long story short… this combination has been outstanding with the Super 12. Highly recommended. BTW… my amps are Wright 3.5s. Update on cables: As Tim and I exchange notes on tweaking the Hammer, and the sound continues to evolve, certain things are becoming apparent. Over the last couple days I've come to a conclusion on wire and I have a confession. The wires that sounded the best with my Spendors are the same wires which are now synergizing much better with the Hammer. I have found the Mapleshade Single Helix speaker wire ,while still a viable option because of its price, is not in the same league as the Harmonic Tech Pro 11. Yes, there is a massive difference in price ,but the HT stuff is simply better in every way. A parallel conclusion can be drawn when directly comparing the Single Helix interconnect to the HT Truth-Link. While my enthusiasm has mellowed on the Mapleshade Single Helix wires, I feel it's still worth an audition for those on a budget. As the Hammer becomes more refined with various cabinet modifications, wires become a less attractive method of tuning this speaker. The Hammer continues to be a work in progress. As it changes, choices in wire that will best synergize are bound to vary as well. The Hammer now, unfortunately, places the least expensive Mapleshade under tougher scrutiny. ConstructionI've placed my Hammers on 11"x11"x 2 1/4" thick MDF platforms which in turn are spiked to the floor. For those who build the Hammer out of MDF ,here's one simple solution on getting that raw cabinet to finish look status. When I first embarked on this project ,my intent was to prime and spray paint the prepped raw cabinet. Eight cans of aerosol spray later, I realized two things. There isn't much paint in an aerosol can and I was never going to get an even professional finish on the Hammers unless I used a real spray painting set up. They're just too big. The other option ( and don't shutter here) was to roll on a latex interior paint. Why not… I'd already sealed and primed the cabinets with 8 cans of oil-based spray. I choose a flat interior latex that very nearly matches the walls in my listening room. I also choose a medium knap roller to give the Hammers a "dimpled" finish. Two coats later , I had a very professional looking finish that has drawn a lot of compliments and is very easy to touch up if needed. As a bonus, the Hammers don't call attention to themselves because I was more or less able to match the color of the listening room . Bottom line is that there are several ways to finish the Hammer. This is just one that might appeal to some because of its simplicity. (Editor's note: I did exactly this but using a very fine knap roller and used medium gloss black latex, see the results here). Hiding the peanuts……… Yeah, when I finished the Hammers and set them up, one thing I saw wasn't going to cut it — the sight of the packing peanuts through the port. A simple solution is to simply lay an 8"x8" piece of black vinyl sun screen ( Ace Hardware ) on top of the peanuts right at the mouth of the port. The sun screen just lays on the peanuts and doesn't impede the port in any way. Yeah, if you really get nosey , you can peer in and still see them, but for the most part, the port now just takes on the appearance of a black hole from almost any angle in the room. Deflex and Mortite I took Tim's lead here and eliminated the grey carpet "curtain" from the Hammer's interior. The grey carpet only remains at the top of the Hammer's interior. and was trimmed to slightly overlap the Deflex which is mentioned next. In place of the "curtain" and directly behind the 12" driver is a round Deflex Subwoofer panel . This is trimmed and glued( Weldbond) to the speaker's rear baffle. As Tim suggested.......leave the acoustic sound deadening panels in place and glue directly on top of them. I also added a standard Deflex panel below the Subwoofer panel. This is trimmed to fit with the scraps used to fill in the area at the top of the Subwoofer panel where the deflex will meet the grey felt at the speakers interior top. The rest of the cabinet's interior remains "stock" with bubblewrap, packing peanuts, etc. Once again at Tim's suggestion , Mortite or rope caulk can and should be used to damp the basket of the 12" driver. I did not use nearly as much as Tim, but I did manage to work some of the Mortite into the basket's interior frame . There's only a few areas (the driver basket's six "spokes" or framework between the openings in the basket) that can be reached safely, but it's worth the effort . BE CAREFUL ,however, as the driver is very close and the lead wires to the driver are especially in peril IF you get a little clumsy. If in doubt, don't do it. Damping the exterior of the basket is a relatively safe proposition and well worth the effort as well. One of the last conversations I had with John Wyckoff was concerning his trip to Las Vegas for "The Show". What I remembered most about the conversation was the fact that John was amazed how the Hammer transformed when they began using 845 based amps putting out between 25-30 watts per channel. Now, bear in mind, these were some very expensive designs by Cy Brenneman, ( spelling ? ) Recently I gave the Wrights a rest and put my CJ MV 75A1 back in the system. I hadn't used this amp since the Hammers initial break-in and just felt the drivers could use some more "exercise". I also kept recalling John's comments on the effect the "bigger" amps had on the Hammer. I decided to run the Ei KT 90 IIIs in place of the Svets because I felt its" leaner" nature would better synergize with the Super 12. No 845 triode magic, but indeed more power and around $9000 more in this tightwad's pocket, as I believe the above mentioned amps went for around 10 grand. I let things warm up a bit and returned to listen. Since I wasn't expecting much ,I certainly wasn't prepared for what I heard upon returning. To put it bluntly........the Hammer never sounded better. You'll never know the true weight and dynamic ability of this speaker until you give it some juice. The Wrights were just tickling the 12s by comparison. Do I miss the SET here? Well, certainly not yet, as the remarkable sense of ease this combination presents is very addictive in its own right. Time will tell , but for now let me say, don't be afraid to use a high quality P-P amp in the 30-60 watt range with the Hammer. You might be pleasantly surprised....even shocked. So, the good news is ......the Super 12 sounds pretty dynamic and gutsy with strong 2A3 amps such as the Wrights.....and the good news is......the Super 12 might even be more to your liking with a high quality, quiet P-P amp..... and it doesn't even have to use triodes as tightwads like me have discovered. The bottom line here is that you can enjoy this speaker with a wide variety of tube amplification. Michael GreeneWell... I didn't want to drag you down with minutia but since you asked :) I like the Super 12s a lot - the images are bigger and more life like and they have a larger range of micro dynamics, as compared to the typical multi-driver high end speaker. My other speaker is a Zalytron three-way using the ceramic Accuton drivers and somehow, the Hammers seem to have different kind of transparency that is on par with the Accutons. As I explained to a guy from the forum, one builds something like the Hammer because of word of mouth and word of mouth says that the tweaks make it even better, so I built it with all the tweaks from the site. (Except I did A-B tests with the crossover and notch filter, starting with the stock crossover). I used Deflex on the top and back inside panel behind the speaker. Bubble wrap everywhere else and covered the back and magnet of the speaker with Mortite. I have found bypassing to be interesting with the Hammers. I thought polystyrene bypass caps sounded better in the tweeter than teflon (I happened to have a couple of small Rel teflon caps from another project). On the notch filter, I bypassed a Solen with a smaller Hovland and used a Mills non-inductive for the resistor. On the crossover proper, I ordered the Alphacore inductors directly from Alphacore after having read that upgrading the coils was a good idea. Alphacore will make custom values for the same price as the next higher value from their pricelist. The total was about $80 for the six pieces and they arrived the next day! The Alphacores are definitely more transparent but initially less warm, after break-in though, I don't see any downside. A guy on the basslist wrote: " > What kind of differences were you hearing [foil inductors] compared to a standard air core? Considerably cleaner, less distortion, particularly in the lower midrange, where the largest caps and coils were located. The ribbon coils seemed to open up that frequency band (200 Hz to 1,000 Hz), revealing more detail. That is an area of the spectrum that I had not paid enough attention to, and I found that there is a lot more stuff going on there than I had thought. When it came through in more detail, the difference was immediately audible. Higher Tympany, kettle drums, Bassoon, and male voices were the mostly notable beneficiaries of the improvement. Were I using a passive filter on the bass, I imagine the improvement in the bass frequencies would also have been very noticeable. The coils seemed to make more difference than the change in caps. " I am also using Mills on the crossover and a variety of bypass caps. I found that a paper in oil cap sounds very good on the 12 (note that the Tannoy guys are very big on Jensens). I found that I liked polystyrene better than teflon for the tweeter (I happened to have a couple of small teflon caps from another project). Don't want to bore you with more, but I agree that the cabinet and the speaker in general could probably be optimized to a great degree with more work. I see that both Shun Mook and Tannoy (in its new concentric top of the line speaker) are both using birch ply for the cabinet walls... hummm. Pictures of Michael's modifications (Below) Detachable back panel showing the long ebony brace and deflex pad. The half moon shaped pieces were leftovers that happened to fit at the top. 
(Below) The top of the cabinet shot from below the speaker. Note that the deflex pad is split into three sections. The thin middle section covers an ebony brace on the top panel that goes from front to back. I had a lot of trouble finding an adhesive to make this stick long-term. I finally went with my old standby - Permatex liquid gasket from the autoparts store. The type marked "OEM certified" is non-corrosive. 
(Below) This pic shows driver damping; The zobel - consisting of 10uf Solen/2uf Hovland/0.1uf Crescendo - note that the zobel is tied to the driver by zip ties - one is tied around the magnet and the one around the zobel loops through it.; the bracing scheme is shown as well - the ebony front braces are shown above and below the speaker and the side braces of bocote are visible on the sides. 
(Below) External crossover using clip leads to make quick connections. This is my current bypass setup (not any more, see notes below in Discussion). I have realized that the Hammer 12" is transparent enough that it benefits from tweaking the crossover to accommodate the type of amp being used. Using 211's (bright sounding) I had an oil cap in the woofer network. With the Billies (300B), a 1uf Axon sounds great in conjunction with the large bennic. Lukas Finkas said a while back that Axons are great in crossovers, but I just happened to try it here on a lark and discovered that he is right. (The small gudeman oil cap as a bypass adds width and liquidity). 
Notes from the Full Range Driver ForumRegarding the Crossover: Written by Tim Adams at 01 Dec 2002 22:14:19: Lately I have been listening to the Hammers without a low pass filter [ 0.24 mH inductor - editors note ] on the super 12 driver.. and a 1st order high pass on the tweeter crossed(at present) at about 9500... It is a much..much faster and more open sounding speaker in this configuration in my opinion.... (and everyone else who has heard it) ... try it ..... :) In short... just a notch filter and zobel on the super 12 and a single cap on the tweeter... *** Written by Brad at 02 Dec 2002 20:40:31: A 1st order crossover at 9500hz for an 8 ohms tweeter, yields a cap value of 2.09uF *** Written by Tim Adams at 02 Dec 2002 20:48:26: 1.8mf Hovland.... still a tiny bit too low a cross point I think but very good....I will fine tune it with a friends spectrum analyzer when I get a chance. The huge improvement is getting rid of the low pass filter on the super 12 driver.... (.24mh if memory serves.. ) ... and allowing the driver to roll off naturally. I was using the best inductor I could find too.. (10ga Northcreek)..... frankly ... it is so much better without it that I am shocked one of us didn't try it sooner. *** Written by tianguis at 03 Dec 2002 00:46:19: Tim: Last night, I immediately leapt on my external X-O and made the mods, after checking into the correct value for a first order cap for the tweeter. My first post was incorrect about the value and I'm now using the awful 1.8 uf Bennics. Even so, I must say the difference is amazing. After about six hours of listening, I find them to be more "toe-tapping" good. The bass doesn't seem as taut and the highs aren't any sweeter, but overall listenability seems to have improved. I've also gained width in sound stage: the change seems to have affected off-axis performance. They're not as sensitive to placement and toe-in as before. I've been investigating recommendations for replacing all the x-o components. If this mod works, and it certainly seems to, I'd much rather spring for a pair of really great caps than have to take a chance on a combo of parts which may or may not perform much better than the parts they came with. I'm using the newer tweeter, but I'd be interested in hearing of your spectrum analysis and recommendations for caps. *** Written by GM at 03 Dec 2002 19:20:28: Have you tried paper/oil caps? This as good as it gets IMO, though they have to be periodically replaced to maintain peak performance. *** Written by Mike at 04 Dec 2002 16:22:48: After playing with removing the low pass filter as per "Super" Tim's thread below, I too am amazed. The speaker sounds more like real music - timbrally speaking. The high midrange distortion or hardness that I thought I was hearing (that made me wonder about long-term listener fatigue) seems to have been an artifact of a particular bypass cap I using - and went away when I took it out of the circuit. Dime store theory: It seems that after removing the low pass filter, the sound of each cap in the notch filter is laid bare, so to speak - i.e., it is very easy to hear the sonic signature of each different cap in the circuit. Could John have used the low pass coil to help mask the sound of of the typical low cost caps that made/make the kit affordable? *** Written by Tim Adams at 04 Dec 2002 23:47:04: I am happy that you have had good results.. I have been swamped with work this week.. but hope to get to the spectral analysis soon.. I have always favored the sound of a 1st order Solen Split over a butterworth... which would indicate a cap value something under 2mics... Fankly... I feared the hf breakup would be more fearsome than it is.... I find that the driver is now somewhat more unforgiving of problems upstream... Which is a very good thing IMO.. ON good recordings the improvement is very substantial to my ear ... tonality is much improved.... BTW if you want to make another real improvement... loose the peanuts and replace with a pair of Deflex subwoofer panels in the bottom. *** Written by Mike at 05 Dec 2002 16:41:13: I did a search on the Asylum this morning and it seems that the consensus is that the Audio Cap Theta is the best speaker cap available - not cheap though. Last night, I tried a pair of 1 uf Infinicaps (new) as a bypass for the Bennic with very interesting results. There was an immediate revelation of far more detail w/o brightness as well as good tonal color - as opposed to the VTV silver/oil which had more air. THe new line of infinicap includes speaker caps at a similar cost to Hovland and Theta. A 1uf axon tin foil was also pretty good w/o sounding bright in the bypass position. I read that the Axon Tin Foils sound a lot like the Thetas but AFAIK the largest value is 1.5uf. As Greg B says below, the AN Oil caps (not Jensen) are pretty dark sounding and not a panacea - although some claim that they need 300 hours break-in. I also thought of trying oil caps and poly in oil like the GE 97F which is current production, sold by Newark. I like the GE's a lot for power supplies and decoupling. If I break down and go for the Theta's I will report. *** Written by Greg B at 04 Dec 2002 21:45:10: > For the record, I am using the 7uf bennic (IIRC re the value) with a 1uf Ultratone silver and a 0.5uf AN copper in oil (new style) as a bypass. This is very smooth. So far, all other bypass caps, including some NOS paper caps, seem too bright. Maybe your source is bright? I have mixed feelings about PIO caps. I had some Jensens that I tried as coupling caps and hated them, so I tried to salvage some use out of them as bypass caps in a crossover. They ended up having much the same sonic effect, at first they seemed smooth yet detailed, but it shortly became obvious they were just masking things with their characteristic added distortion. They quickly grew fatiguing. Give me a high tech plastic flavorless Auricap anyday, IMHO. Strangely, in the larger sizes - say 50 uF - needed to cross over a full range or big horn to a woofer, oil caps seem to sound the best, IME. Any theories about this anyone? Anyone know where a good cheap source is for large PIO caps? I hear certain brands of motor run caps sound good. Greg B *** Tim Adams: I have finished with the crossover modification and have also found what may be the perfect tweeter for the Super 12. The tonal problems with the Super 12 were largly due, in my opinion, to the lack of phase coherence caused by the overly complex crossover(3rd order with notch).. (get those parts out of the path!) After removing the .24mh low pass filter and replacing the entire tweeter circuit with a 2mf cap (turned out best brad!) this was resoundingly confirmed.. The crossover now seems to be acting like a quasi-1st order.... with all of the inherent phase and tonal benefits.... I have been playing with some Fostex drivers of late and decided to try the Fostex FT17H with the super 12's... OH MY! Bullseye!... It is mounted on the top of the cabinet and angled towards the listening position.. What a wonderful tweeter!... extended, fast and dynamic... It provides near perfect integration with the Super 12 and is a much better match than either of the audax units that have been included in the kits. Imaging, dynamics (macro and micro) and musicality are all much improved. BTW Mike.... You were right about the Audiocap Thetas... To my ears there is no contest... much smoother than the Hovlands and... even more detail. I am using a 2mf on the tweeters and a .5mf bypass in the notch filter. Enjoy, Tim *** Various people have tried removing the Super 12 .24 mH low pass filter, and some prefer it, and some don't. Michael Greene has gone back and forth and prefers leaving it in. *** Several people are reporting very good results with the Fostex FT17H supertweeter. Top
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