Marvel

Dean, the second reviewer puts rocks on top of his gear to stop resonance.... That is REAL Voodoo!

One way is to use a defunct tube and insert/remove a few times. If you have an old tube, you can wrap it with tape ( a lot of tape) so if you break the glass you might not hurt yourself. Or take an old tube and remove the glass and mount a wooden handle in it. You used to be able to get old octal and other bases for mounting your own circuits. One of those could be used the same way. Maybe you could just solder them in... when one goes bad you replace the whole assembly. Bruce

I'm in the NW burbs almost every weekend and check out Saturday's Audio pretty frequently. Thanks much for the invite.........I would definitely like to get a listen. In fact, I will be attending the AK (tube) fest next Saturday in Northbrook. I'm bringing my JM Peach, other members are bringing tube pre's, tube cdp's, tube amps and various speakers. I'm curious to check out the Dynaco ST-70..........seems like they're everywhere. Kev, I'm curious how you would compare the Wright's with your Moondogs. Maybe you wish you hadn't passed them on to someone else? Bruce

I couldn't agree with you more, Craig. I think that is one of the reasons my LaScalas are working so well with my Moondogs. The crossovers are a constant impedance, which the low powered tubes like. It works for me. That's why I am not sure how the Heresies would work, or the RB-75s. They have different crossovers, even if the efficiency is almost the same. I am sure they won't work the same on any given amp. My old JBL 4311s are only rated at 89db, yet JBL indicated they could be used with a 10 watt amp for monitoring purposes. It will depend a lot on the amp matching up with the design of the crossover. Bruce

I keep telling myself to hook up my Moondogs to my Heresy IIs, so I could give my own opinion/half baked/ partially qualified answer. The Heresies aren't as efficient as the LaScalas, etc., which I have my 2A3 amps hooked up to. Almost the same efficiency as the RB-75s (RB-75 is higher). I've not heard the RB-75s, so I don't know the sound of them. They are rated slightly lower in the bass than the Heresies. All that being said, I don't listen to my HIIs at a very high volume level. I might find it acceptable.

Of course I spoke too soon. I don't know the differences for the Khorn compared to the LS, which is what I have. Dean is right about just replacing the caps on the ones you have first. I think that will be a huge improvement for very little cash outlay.

You know that Bob can just refresh your crossover with updated parts, keeping the same specs. I built a set of DHA2 crossovers, a constant impedance type with fairly low cost parts (Dean sent them to me). I got the autoformers from Bob. I can look up how much it all cost if you want an idea. Bruce

As everyone is going on about how much they like their SET amps, I think the big problem will be the efficiency of the RB75s. After hearing the higher power on the HT system, using the lower power on the RB75s for two channel will probably come across as a bit weak. There are very good tube amps in all kinds of flavors covering a wide price range... just take your time and try some others out if you can. Bruce

If what you have is a push-pull, most SETs aren't going to be what you want. Does your MiniMax use the 6BM8 tube? This is pretty much the power you will get from a SET: A SET made with a 45 output tube is only about 1.5 watts, 2A3 tube about 3.5 watts, 300B tube 8-10 watts. You can get some SET amps made with higher powered exotic tubes, but they will cost you a lot more money. YMMV Bruce

I have two of the HK430 receivers. My youngest uses one at school on a pair of JBL L46 and I use one at home to feed my pair of Heresy IIs. Great little receivers. They are a good match and you certainly should be able to get one for < $100. Bruce

Welcome Stuart! To post pics (and we all love to see pics of our purchases...) you do the following" At the top of the reply window, there are five tabs. Compose, Options, Related, Preview, Smiles Library. On the options tab is a button for a file attachment, labeled Add/Update. Click on it and browse to where your pic is on your pc. Once you do that, you will probably have to scroll to the right to see the save button. Once is is saved, you can post it. Unfortunately, unless you host your pics somewhere else, you can only put one per post. Bruce

I would say that Klipsch built a lot of them, too. Andy, aka HBDR Builder, posted this, commenting on his time at Klipsch. Someone had asked how long it took to build cabinets. Heresys, mitered, chain w/clamp build: Normally one builder used. Everything running smoothly and not including prep time, about 7-10 minutes each. Heresys, mitered, pneumatic assembly jig: Normally one builder used, about 5-6 minutes each, not including prep time and provided everything went smoothly. Heresys, birch decorator, flush front style cabinet: normally one builder used. Provided everything ran smoothly, about one every 3-5 minutes, not including prep time. Heresy, birch decorator, drop-in front style cabinet: One builder, about one every 3-5 minutes, provided everything went smoothly and not including prep time...Often the builder had a helper to install the rear glue blocks, caulk them up, and then install the drop-in front. When Heritage speakers were the only home speakers Klipsch made, the Heresy was the bread and butter speaker, profit-wise...especially the decorator versions! The Klipschorn made Klipsch famous, but the Heresy, with its ease of assembly, low cabinet material costs, and HUGE numbers of sales, etc...made the company GROW! Not bragging, but I normally built at least 200 birch Heresys in a full day...SOLO!...and quite often built far more than that. With a good helper, that number regularly exceeded 400 in a day!

I believe Klipsch also did five tweeters on one of the MCM systems. Mostly for power handling.

Just enclosing the cabinet isn't as smooth and distorion is increased. Porting evens out the repsonse and lowers the distortion levels, as Dennis mentions above, but I have copied here:"Simply making the box larger gains at 31hz, but you lose 3dB at 50, 63, and 80hz. The vented (without EQ) has about 3dB more output than stock at those same frequencies. While the vented has only 2dB more output than large sealed at 31hz, it's 7dB more than stock. When EQ is applied things change. EQ applied at 31hz will cause distortion and increased cone motion on the sealed system, on the vented system the EQ is at Fb and thus does not eat up cone motion or increase distortion" Mike just needs to build one of these and try it. (As do I, and adding the box underneath is easy. I'll do it with mdf or particle board, at least for testing)

Do you know the details of this testing? I went ahead and plotted the numbers on a graph, which seems to be showing that the port is essentially doing nothing compared to simply making the rear volume larger...the measurement also looks to be swamped by the modal distribution of the room the speakers are in. I have no idea how they did the testing, but a 2db gain at 31hz is not bad, on top of the 5db from the box volume change from stock to Pete's 4.5 cu ft. Dennis is figuring 4.8, probably not enough of a difference to change the results much. Does anyone have accurate numbers for the area expansion rate on the lascala? I would like to dump them into hornresp and model what the port should theoretically be contributing to the system (and then compare to the measurements provided). I should have whipped together a graph way earlier on, because it's showing mostly what I would expect from the system... Dennis posted this before: The taper rate of a LaScala is 100hz,The mouth area is good for 125hz. Below this it is a big woofer in a small sealed box. If we plug the T/S parameters for the K33E into a box program we will see that the Qtc=.85, the Fc=82.5hz, and the F3=70.9hz. If we close in the back of the high frequency cabinet and open the woofer rear chamber up into this volume and fill with fiberglass we now have Qtc=.577, Fc=58.2hz, F3=73.6hz . I think Dennis has said that under 125hz, you only need to think of it as a sealed or ported box. The horn has little to no effect. He did post about room gains when using the filter ahead of the amp: Boost is applied ahead of the amplifier and is usually Q=2 at Fb. Fb is sort of experimental with the smaller magnet woofer liking the shorter ports. Part of this has to do with room modes. The small sized bass horn does nothing below about 100hz, but floor to ceiling gives us boost in the 70hz~75hz region (7-1/2'~8'), and wall to wall (short wall) in the 47hz~51hz region (11'~12'). An Fb around 31hz~35hz seems to work best with these room sizes and speakers. If you have an actual wall for the third wall (most newer homes don't, they have a large opening into a 'dining' area) and it is around 16'~20', you may have to lower the Q of the boost. It should be pointed out that most recordings are rolled off in this area and a little extra boost is nice.

Don't you still have about four months before the ice goes out? []

I haven't actually checked with Klipsch about it yet. My youngest is headed to Europe for an orchestra tour in May, and it's $3200. So....between that and a couple of other things going on in my life, the cash isn't there. My plans are always bigger than my wallet! [*-)]

With a quick calculation it should fit on one sheet. And if you would rather do a slotted port, Dennis gave me these figures: The vented LaScala as I described runs to about 4.8 cu ft net. Two 4" ID by 7.25" long ports gives an Fb=35hz. A 15" by 1" port would need to be about 5" long for a 35hz Fb. A 13" by 2" port would need to be about 8-7/8" long for a 35hz Fb. A 15" by 2" port would need to be about 10-5/8" long for a 35hz Fb It helps to have a good software port model, the long narrow aspect ratio requires a different length than the same area in a square or round port. It also helps to start out a bit long, and trim it shorter to reach your target Fb.

Have a read... they worked out some wiring issues, etc. I am really wanyting to do this myself. http://forums.klipsch.com/forums/t/100889.aspx?PageIndex=1

Pete Fowler and his buddy built a new set of cabs with the added space. Testing, they came up with the following figures (I think with no eq filter between the pre and power amp): 200 160 125 100 80 63 50 40 31 25 20 HZ 77 80 79 73 72 78 68 60 61 52 51 dB Stock, mouth braced 76 78 78 73 69 75 65 60 66 56 52 4.5 cuft, no ports 76 78 77 75 74 80 70 60 68 54 54 Two 4"dia 10" ports 76 79 78 76 75 80 71 60 68 54 53 Ports cut to 7" The interesting thing with 10" ports is the boxes went deep, but the snappy, fast horn sound was lost! Cutting the port length to 7" brought the snap and speed back to same as stock, plus the lows remained, esp. at the 31Hz box tuning point. This data is with K33E driver and light stuffing. We think a K43E in this box would be superb, but haven't tried it yet. Neither of us is going back to stock. Pete

Speakerfritz, This is for all the cowards out there who would like to hear what it sounds like without putting any marks on their present cabinets. Also, some have said they wanted to raise up the cabinet some. This is ten inches, which to me would make them too high. Of course, since most people don't have their LS all the way against the wall, you could adjust the depth and lower it some. If you don't like round ports, you could do a slotted port as well. I might find that more attractive. Here is the mod done to the top:

Without a filter between the pre and power amp, Dennis says the bass can sound a bit lean. " The net volume was found to be correct for 6th order tuning for the K43 woofer (B6) or quasi 6th order tuning (C6) for the K33 woofer (in the stock LaScala). Vents are typically two 4" diameter by 7"~10" long. Longer is tuned lower, in general the larger magnet woofer can handle the lower tuning. Boost is applied ahead of the amplifier and is usually Q=2 at Fb. Fb is sort of experimental with the smaller magnet woofer liking the shorter ports. [i.e., the K43 could use the 10 inch ports, while the K33 works better with the 7 to 7.5 inch ports] Part of this has to do with room modes. The small sized bass horn does nothing below about 100hz, but floor to ceiling gives us boost in the 70hz~75hz region (7-1/2'~8'), and wall to wall (short wall) in the 47hz~51hz region (11'~12'). An Fb around 31hz~35hz seems to work best with these room sizes and speakers. If you have an actual wall for the third wall (most newer homes don't, they have a large opening into a 'dining' area) and it is around 16'~20', you may have to lower the Q of the boost. It should be pointed out that most recordings are rolled off in this area and a little extra boost is nice."

Here are the basics, gathered from some users who have built this mod to the La Scala bass bin. thanks to djk for all the design, input and figures. First, let's assume you only want to try this out and not make any permanent changes to your precious LS cabinets. Sounds fair to me. Build a box to go underneath the cabinet, after first removing the bottom cover. This box will have a matching opening to mate with the LS bottom, and two ports, using 4 inch pvc for your favorite building supply store (Home Depot, Lowes, Menard's, etc). Considering the LS is about 125 pounds, I certainly wouldn't use anything less than 3/4 inch. Dennis says this for the size: "I'm looking for a total net volume of about 4.8 cu ft. I figure the stock back volume is about 2.25 cu ft. Call it an internal height of about 9" (22.5 X 22.5 X 8.70 = 4404 cu in = 2.55 cu ft). Two 4" ID by 10" long ports displace about .15 cu ft so 10" outside is close enough." Comments made by some folks who have built this, have lead them to shorten the ports to around 7 inches. This retains the snappiness of the horn but gives the lower bass. Here's a simple drawing:

wrinkles - I'll start another thread for this... so this one won't stray too much more off course. Bruce

I have most of the data that Dennis posted about the bass mod, including the filter at the front of the power amp. Nice to do that on the Crown... I made the 3D drawing of the mod, and can give you dimensions, but it is just a box with the ports in it. Three quarter inch material (mdf or ply), ten inches tall, to match the width and depth of the LS. You have the port sizes to go with it. I'll dig out the details and email them to you. Bruce