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Yes, I've been reading and learning a lot today, from JBL literature and a sister board to this one for JBL: http://www.audioheritage.org/vbulletin/index.php I was mistaken, the Potato Smasher horns and Acoustic Lenses are mutually exclusive. Thanx for the link. Does Jersey have a monopoly on JBL stuff? [] Another place was recommended to me from the AudioHeritage board also in NJ.

They say a picture's worth a 1000 words... [H] I just did impedance measurements the other day (shocking midrange hump with the network from the autoformer I'm assuming) . Will be doing frequency tests soon. Thanx everyone for the replies. It was very helpful. I see the impedance peaks a tad around 450 and drops relatively above 500 (while on an upward slope) so my amp will correct for that dip a bit; more on that later. The impedance is affected by horn loading (shows rough peakiness) up to 1.5k but I dont' think I'd want to go there. I decided the 'Potato Masher' JBL Horn (needs an Acoustic Lens) on eBay now would not be a good match. I've inexplicably always wanted a speaker that uses an Acoustic Lens every since I first saw it decades ago. That lens isn't good down to 500 unless used with a verticle baffle; I don't think the edit:K701 K401 location is enough of a baffle above it and the bass horn is below it. (where's that boo hoo smiley) [:'(] Hell, maybe I'll try it anyway though. I actually have the 701 horn and newer driver, but I'm sure all that valuable information holds just as true with that. What may come as a surprise though, is I'm planning on removing the passive network from the picture, and tri-amping using a transconductance amp (aka constant current, aka variable voltage, aka variable gain, aka impedance follower [8-|] ) of my own design. Parts should begin arriving in the upcoming weeks and I'll begin breadboarding and testing after. If I like that but decide the 'gainclone' IC (for DIY simplicity & most importantly low $$$) that I'll be using isn't 'audiophile enough', I have some transconductance tube amp designs I may give a try and build.

Thanx very much. I decided I'm going to go for it. Yes, reading up on the technology I believe it would not work well in front of the K701 and I need a Potato Masher horn with it, as the concentric circle screen they employ enters into the dispersion through the lens --- but I've still wanted one for a long long time for some unexplainable reason so I think I'll pull the trigger. Thanx again.

Hello, Wondering if someone can help me. What is the 'clean' upper frequency capability of the La Scala's bass horn? When I put a tone sweep to it w/o the x-over network, it puts out nice level even up over 1K. However I know that doesn't mean the cone won't operate in break-up mode with a complex and powerful music signal. Also, I'm pretty sure the horn may/will become 'beamy' or lose effectiveness above a certain frequency as it does at a certain low frequency. So taking the horn and driver capabilities into account, what would be the highest frequency I'd want to cross the La Scala horns over to the mids? I ask because I'm toying with using a mid horn that isn't capable of going down to 400hz. Does the bass horn do well to 600, 800 or 1000 Hz? Thanx very much. p.s. anyone know the power handling of the K-55 driver with x-over @ 450 or 500, as well as dispersion of the edit:K701 K401 horn?

A bit OT, maybe not. Insired by the pic I see above, I've actually been wondering about replacing the stock horns & mid driver of the La Scala with the Altec or a JBL in its place (removing the tweeter from where it is of course), and seeing if I can find some used JBL 2404H tweeters and mount them on top ... what do you think? Am I straying too far from the Klipsch camp if so? Otherwise I'd keep the mid horn and just replace the tweeter with something 'better'. Any opinion? The latter would be better to have sitting under a bigscreen, as I wouldn't have a tweeter sitting up above the speaker. [] Thanx again.

Hmm... interesting proposition. Would you be providing the bass driver, mid horn & driver, and tweeter, or would I? I don't need passive x-overs. E-mail me through the board to let me know what the price would be. Thanx very much, Steve.

Has anyone ever tried an acoustical lens on a mid hor on the La Scala? Specifically, the JBL 2310 Lens, which is 20x7 ??? http://www.jblpro.com/pub/obsolete/Acoustic_Lens_Family1.pdf I have a day to decide how bad I want it. Would love to hear your thoughts on how the Klipsch horn mates to an acoustical lens. If it's a good match, I have to of course consider one on the tweeter then too... [] EDIT: corrected the title (I hope that changes the title on the main thread too)

Sorry if I missed the post saying so, but are the La Scala clones still for sale? If still for sale, anyone in his area interested in just one, for a center? I'm in need of a single for my center, and would love to go in 1/2s with you; however I need that single shipped up to me in LI. I bought my current La Scalas from down south and they were shipped up to me here in nice big boxes. Boxing seemed pretty easy, just big.

I finally got my Terrasonde out to do impedance measurements (had been so long the battery won't hold a charge anymore). I need to transfer them to the PC before I can display them (unless I take a digital photo of the display []) I did each speaker as a unit and then each driver individually w/o network. I don't think I'm up to the task of the simulation based on what you're describing mixing T/S parameters and horn theory sadly though. Regarding my measurements, all I can say is I'm floored, shocked and dismayed! The impedance hump in the midrange is frightening in its 'massiv-isity-iness'! Now I see what Al K had been 'soapboxing' about and against in the past. Also surprising is the bass horn got into the low 3 ohms, with the mid driver+horn remaining above 10 or 11. I'm going to have to produce a higher current constant current amp then I had 1st planned for the bass; easy though with the LM4780 'gainclone' chip I settled on. BTW, very interesting what you're saying about the mid & bass horn response. Based on 'by ear' tone & sweep tests (yes, will do those advanced time domain tests I purchased for the Terrasone that can measure frequency response and basically removed a room's interaction from the measurements) directly driving the driver (no network), I see how I want to x-over the mid horn at 450 or 500. I thought the bass horn did fairly well above 400 hz myself (again, sans network). I don't know about the bass horn's polar response though. BTW, do you happen to know the K-55 mid horn driver's electrical power handling? I've come to discover that's somewhat of an enigma based on a search of this board. -steve

By my final thought, I meant maybe I'd do just one amp and re-do the x-overs at the higher combined impedance of the source & load. Either way, this got more expensive; there's no "cheap" way to enter into this experiment ... Either I have to go fully active with three cc amps, or one cc amp and new x-overs. I thought I could just 'try it out' but see now it's a bit more of a comittment.

Ah, now I understand the error of my ways!!! I didn't understand the whole issue. Based on this post here, I now understand: http://www.audioasylum.com/forums/tubediy/messages/60883.html The operative statement being: I have a three-way with xover at 300 and 3500Hz. The output impedance of the amp is in series with the impedance of the speaker drivers, so the crossover must be modified for approx 55ohms, and not 8ohms. It's so simple makes me ask "why didn't I think of that". Looks like before trying anything I'll be pulling out my good old Pioneer SF-850 selectable electronic crossover and will need to build three, not one, transconductance power follower. Argh! ...though, I have built plenty of x-overs in the past. We'll see.

hmmm... I know overal acoustical output is affected "un-naturally" (vs if the driver was driven direct) because @ constant current the input voltage level 'follows' the impedance curve, which is altered by the network components in addition to the driver's impedance .... but that doesn't 'stop' a capacitor's impedance from rising as frequency goes down, or inductor's impedance from rising as frequency goes up. I do know the equalization you mention is more trouble then good to the frequency response / acoustical output when driven this way. I was sure x-over still functions though. I will be approaching this with 'measured' steps, both figuratively and literally. Meaning applying power cautiously, as well as actually measuring the response to the input terminals of the drivers measured with one of these that I have: http://www.terrasonde.com/products/color.php. Using the Little Dot III+ headamp/preamp/poweramp already has transconductance-like drive characteristics when driving speakers; output impedance is much higher then a typical amp. That's what 1st whet my whistle to this. That, and the fact that, - transconductance drive of the squawker driver provides a natural dip in power to the mid portion of its operating region where impedance is low - transconductance drive of the hors, bass horn especially, provides a natural increase in power delivered at frequency where the impedance is high. Thanx for the warning. I'll be sure to perform as FFT/RTA scan of the frequencies each individual driver is seeing when driven by a constant-current source.

As the title reads, I'm wondering if anyone has driven k-horns or la scalas with a transconductance [constant-current] amp before? Did you try it tri-amp'ed? I plan to do so driving my la Scalas using a modified power-follower circuit driven by my Little Dot III+ amp. Anyone try it before? I heard transconductance drive works well with horns, so thought I'd give it a try. Ideally, transconductance amps should be connected right to a full range drivers without typical parallel type crossovers designed to be driven by a voltage source amp inbetween the amp and driver. My finish line is using one custom built tube pre + ss constant current power follower per bass, squaker & tweeter, electronically crossed over of course. But trying this route with the three drivers + parallel x-over network driven by one constant-current amp for now.

Thanx for the references. Found one and will look for the other shortly. I realize I actually should go the reverse engineering route with manual interpolation I think. I took Terrasonde's offer to upgrade my AudioToolbox to the latest one (haven't actually used it since though!). I can very accurately measure the impedance of the whole speaker system across the audio frequency spectrum, or each driver individually, each network node, whatever; the system's what I'm looking for right now I guess. I can then create a complex LCR circuit to match the impedance I measured through manually interpolation. I did this with my Martin Logan Sequel IIs actually as just a test to see if I could a few years back. The impedance of my circuit was darn close to what I'd measured. ...call it the "brute force" method I guess. [] EDIT: BTW, I see you like the JBL 2404H a lot. I was thinking about using them on my La Scala then discovered they were discontinued. What do you recommend be used now? (and why on earth would JBL do that?)

Does anyone else remember the massive thread that was finally deleted by an Admin where some guy posts he has an amp for sale? In his handle it reads "have you ever heard of... ..." to which Al responds ya I've heard of it and they are the biggest crap ever ... run away ... yada yada yada ... Turns out that guy is a lover of that tech and bought up all the old stock -- and Al feels he has to make it his unending mission to change that guys mind about those tweeter or at least make sure no other unfortunate soul ever makes the mistake of buying or perhaps even listening to them ever in the future. What an off topic hate / flame fest that turned into; don't know if the OP ever sold that amp. ...well I personally decided I'd never buy x-overs from Al from that even though I was seriously considering it just weeks before, and the reason I was checking in the forum at that time when it was all going down (I showed how green I was as I'd first though he was 'bob' and said I wouldn't buy tweeters from him in that thread - lol & duh). Anyway, I completely lost all respect for him no matter how 'god-like' he may seem given his knowledge. To tell you the truth, I've hardly been back to this forum since then due in large part to seeing what/who was held in the highest of regard. It's a loss yes. But I've seen both sides of the coin.

From what I recall from a few dozen years back is I think it has to do with dampening factor of the driving circuit and how that affects the contol of the bass driver. One cone on the amp terminals sees the output impedance of the amp. Two cones in series causes the output impedance of the driving circuit to follow the curve of the other bass speaker. What -real- effect that has on the electro-mechanical properties of both cones and the acoustical effects it produces is something I can't speak about though other then I think that can result in more resonance when the speaker impedance is high.

Thank you John. A long time audio hobbiest and speaker builder myself but about 15 years out of the hobby, I have a new-found interest in audio engineering spurred on by first, purchase of La Scalas and Heresys, then getting into the headphone hobby with purchase of several pure tube headamps and hi-end headphones. One of those headamps, the Little Dot III+ can actually drive the La Scalas decently; a DH-SET OTL head amp that comes with speaker terminals capable of 2.7watts in triode mode and 3.5watts in pentode mode. I have a desire to experiment with constant current amplification of the La Scalas -- my end goal is a tube-based crossover integrated with a special purpose constant current triamp sections driving each horn independently. But for now I'll stick with a single amp with the passive crossovers in the picture (yes, I know that constant current drive is best used to a single driver w/o passive crossover) I found an intriguing MOSFET Single Ended Constant Current Class-A Power Follower circuit I could build to be used as a buffer and placed between the Little Dot III+ amp and La Scalas to really get things [air] moving --- enter the spice modelling! I'm experimenting with changes to the circuit using a speaker subcircuit, and that's what spurred me to post here. (btw, after trying many software packages, I too find myself ending up on LTSPICE.) I'm hoping to create a -complete- spice model of the 3-way horn-loaded drivers plus crossover network, to use as the load on the circuit. Btw as an aside, coming from one who has built quite a few custom crossovers with great success, your crossovers look exceptional! Even given that my goal is to replace the passive crossovers with active x-over and constant current amplification, I'm tempted to request if you're interested in making a set and selling them to me until I get done ... which I should be honest and admit will end up being a -long- time from now given I'm prone to procrastination [:$] But I digress.... I read your article on Modeling Loudspeaker Performance using LTSPICE with great interest. It was great to come upon this thread at this time. If I make progress on my own I'll post back here. -steve

I do not; I'm in the 'shopping' phase myself. But I've read or heard about many on head-fi.org where I've been spending a lot of time lately. Just pointing links to the places I'm considering them from. I have some pretty 'sik chit' too, and wouldn't consider 'mall-fi sound' myself; but there is some great stuff coming out of China and Taiwan lately (especially tube headamps), where most [all?] of those mentioned comes from, so I'm down for saving some money that way. If anyone's interested, I recommend searching for each on head-fi.org to read thoughts; and google each of course.

I'd ask "define affordable?"... but to speed things up at risk of being on the wrong end of "one man's affordable is another man's 'what the frack, I said affordable', MHDT seems like a good value. Go to eBay and search for items for sale by user mhdtlab. The top of the line is [WAS?!] the Paradisa with a tube buffer output, next the Constantine which is basically the same w/o the tube. Though now I see a "Renaissance II" ; dunno if that's a re-branded Paradisa or a different model. Tube DACs are a buy-it-now of $499. Click for Pacific Valve and their large line of DACs of every form there is; NOS, Tube DACs, Oversampling DACs, and Upsampling DACs.

Thank you 3dzapper. Could be a contender; transformers seem to be the lion's share of cost of it. I love that circuit diagram. I was expecting to see an embossed shadow of a napkin as the background of it.

I know it does and yes I do. ...that is, when the harmonics are of the specturm of the strongest being 2nd order, almost equal 3rd & 4th order, and almost none of the higher order harmonics. Like I mention. I have -clean- tube power already. I want the 'sound' of a DHT SET amp and all that that implies with higher power capabilities then a watt or two ... now that I got a taste of it from the LD III+. Thanx for the candid reply; it's appreciated. And thanx for linx WPM.

I'm looking for an amp recommendation that I can use with my La Scalas in 2-ch mode. I thought I'd ask here. I -would- be interested in a Kit, or even just a circuit that I could build and experiment with. Yes, I know there's NOSValve and many others. I already have a Butler hybrid 5-ch amp and a pair of Audio Research Classic 150 Monoblocks... Both amps extremely powerful radically differing hybrid tube variations. I'm looking for something quite different; pure tube (doesn't have to be OTL) but most importantly I'm looking for one that uses a Directly Heated Triode Tube, in SET configuration I assume. I know those specs are usually in something that measures power output in single digits, and uses a 300 tube. Are there any 20 or 30 watt amps like that? Any that aren't in the thousands of $$$? edit: I'll add ... asking because I got a taste of this hooking up my Little Dot III+ directly to the La Scalas (I posted a thread on it last night). Rated as 2.7W in Triode mode; but me thinks if you want to keep distortion in check you need to keep the draw under 1W. It becomes obvious to me that while it's capable of driving speakers, it's -way- out of its comfort zone doing it. (comfort zone is as a preamp and most specifically as a headphone amp). Thanx for all informed replies.

...guess what I decided to try today.... . . . . . . . ...by that, I mean... This is a mirror off a post of mine from head-fi.org ... The Little Dot III+ is a pre-amp, headphone amp, and power amp. A wider view. I disconnected the Klipsch's from the Butler 5-ch amp and decided to see what the Little Dot III+ had in it. I used a iPod G5 to drive it instead of my DVD (dunno why ; it was easier? ; more easily varied music selection I guess) 3.5W in Pentode mode; 2.7W in Triode mode. I spent about 1 minute in Pentode mode. ...I sooooo like Triode mode. And this uses a direct heated triode power tube ... talk about a throwback to days gone by! But that played a big role in why I chose Little Tube, and I was right in choosing it. Sweet doesn't come close to describing DHT sound. So back to my experiment. It was ......... well ......... errr, ummmm, interesting? Ok, Ok, I thought "WOW" at first. What an interesting sound. Most notably "phase coherent" (sic) I'd say -- smooth, and you actually -felt- the pressure of the music change as phase would change in the music. That hadn't ever happened before. So smooth. Soundstage was huge. (I gotta replace my HT preamp ) That soon became a "this isn't for me" after a while though, when I wanted 'more'. Got ok loud, in an indoor voice; probably 100db? Distortion was high and bass rolled off a lot though. That obviously is attributable to the OTL design using a coupling cap made for impedance of phones, which isn't nearly big enough for an 8 ohm load. I knew I wasn't playing the right kind of music (too much energy; too much bass). But then I realized a series of things. 1) "Lets try this with Classic Rock". Beatles '67 - '70. ....nnnnnice! 2) "Hey I got two M&K Subs" ... Disconnect them from the HT preamp and plug it into the LD III+; check. (that's the wire you see going across the bottom of the screen) Set the subs to variable volume & set to 0db; check. Turn on 24db roll-off @ 80hz ; check. Turn on iPod EQ to "bass rolloff"; check. ....ahh... THAT's what I needed Now w/o much bass signal going to the LD III+ I was able to put it on max volume and not get noticable distortion or much (there is some) compression on transients; there's massive compression driving a full bass signal loud. With that now and all that bass of the M&Ks, Dang, that was frigg'n pretty loud. Sound wasn't perfect, but it was engaging and pleasurable. It's a successful experiment I'd say. One I plan on revisiting many more times, not just this once.

If I were to make a move, I'm leaning towards the BEC myself... though if you believe in the psycho-acoustic benefits an extended frequency range that supre-tweeters brings you how about keeping the stock Klipsch tweeter and supplament it with one of these fostex super tweeters up top crossed over @ say15KHz or so with a 1st order network (to ensure flat phase between the two tweeters)...? http://www.madisound.com/cgi-bin/index.cgi?pid=349 or the big guns... http://www.madisound.com/cgi-bin/index.cgi?keywords=horn ....then scroll to the bottom of the page. edit: Woa... purrty: http://www.visaton.com/english/artikel/art_410_1_7.html but man, are they beamy. I thought they'd be directional but I didn't think that bad ; down about 12db @ 45degrees off axis. I wonder why no manufacturer uses a lens on the supertweeters to widen the dispersion... Haven't found a price on them yet.

..."subtle" would be the word. Let me guess, you didn't read the thread...? You'd read I realized I was a dope and no, it was probably not the direction of the cable but the oxidization on the RCAs that were never connected to for years and years which scraped off on removing and reconnecting the cable.