Dave MacKay

Thanks for the feedback. The THTLP is as close to a corner as I can get it. It's about 10" from one wall and about 3" from the other. I was keen to sort out how to "tune" the THTLP for my peculiarities of my room and my restricted options for placement so that I was interested in using a DSP with it. I considered two alternatives: a MiniDSP 2x4HD with an external amp a plate amp with built-in DSP (Dayton SPA250DSP) To support the MiniDSP, I had considered using a Crown XLS1002 amp with the THTLPs. But, in reply to a question I posed on the BFM forum, Bill Fitzmaurice recommended getting a plate amp instead of the Crown since the Crown was way bigger (1100 watts into 4 ohms) than what the THTLP would need. If I'd gone with a Crown amp, I wanted to use a MiniDSP 2x4HD with it for the THTLPs. But I wasn't at all clear on how I would feed the MiniDSP from my Yamaha R-N803 receiver. I figured I'd have to forgo the simplicity of LFE, send the MiniDSP a "full range" signal, and then just work with the frequencies that would be applicable to the subwoofers. Also, I was concerned that doing so would would likely render the Yamaha's YPAO ability useless. In the end, I went with the SPA250DSP because: it was simpler it was less expensive it provided a DSP capability making the THTLP a powered subwoofer gave more flexibility in placement The SPA250DSP plate amp provides 260W at 4 ohms and deals with frequencies from 10Hz to 200Hz. I'm feeding it via the LFE output from my Yamaha R-N803 receiver. Since I'm crossing over at 100Hz (with, I believe, a 12 dB slope), it shouldn't see much signal above that frequency. Figuring out how to configure the DSP has been a puzzle. Actually doing the config is easy, but knowing what to set the config values at seems like a black art (for now, at least). I have a UMIK-1 microphone and have been playing with REW. It's pretty complex software about an area (acoustics) that I'm not terribly familiar with. I've seen several Youtube videos about REW. However, my background hasn't been sufficient for me to have gleaned much from them. But I'll keep trying. Even at the rudimentary settings I'm using now the sound is magnificent. That's very encouraging.

I just added a THTLP subwoofer to supplement my La Scalas today. It'll be one of a pair, but the other THTLP won't be finished until sometime next month. The THTLP is the third subwoofer I've mated to my La Scalas. The first was a low-end Klipsch unit, the second was an SVS SB 1000 Pro. The Klipsch unit was underpowered and couldn't keep up with the La Scalas, but the SVS SB1000 Pro was a nice piece of gear. However, it couldn't keep up with the La Scalas either --- the bass was a bit anemic; there was no "feel" from it. Even with just a few hours listening to the THTLP, I can attest that it's in a whole different league. It's output is clean and distortion-free. Even at moderate volume (65 to 75 dB), you can feel the bass. The THTLP is pretty efficient too: I have a 250W plate amp driving it, and that's likely way overkill --- I doubt that I'll ever use more than 50W. There are some downsides though: you have to build the THTLP yourself (or hire someone to build it) it's enormous. I built the smallest possible size but it's still 72"H x 15"W x 18" D. But then perhaps a washing machine-sized speaker deserves a refrigerator-sized subwoofer. 🙂

Blackberry was actually based in Waterloo, Ontario. Waterloo is just over an hour's drive from Toronto and a little less than an hour from Hamilton. Mike dropped out of the University of Waterloo EE program in his 4th year after getting a contract (from GM for some displays, IIRC). For a while, Blackberry did all sorts of different things (including inventing a means to sync audio on films, for which they won a technical Oscar) before going on to invent the smart phone.

I first learned of Klipsch when I visited a stereo store in Windsor, Ontario (Canada) with a classmate, Mike Lazaridus. We were researching what to get for a sound system for dances for our high school. Mike was about the only kid in high school who knew anything about electronics. He was incredibly enthusiastic about Klipsch. If I recall correctly, Mike told me that Klipsch was used in labs to recreate sonic booms. (We'd believe anything back then). Mike went on to found Research In Motion, which he later renamed Blackberry.

I wasn't able to open either image. If others are having the same problem, would you please re-post them?

A few days ago I replaced the original tweeters (K-77M drivers and standard lenses) in my 1986 La Scalas with SMAHL v2 lenses and DE-120 drivers from @Dave A The improvement made by the new tweeters is nothing short of astounding! My La Scalas are as original except: I reinforced the cabinets by laminating 3/8" baltic birch to the sides, top, and bottom to reduce resonance (and to address some cosmetic damage) I replaced the original AL networks with new AA networks from Crites To be frank, having wanted La Scalas for more than 40 years before finally getting a pair (in July), I was a bit underwhelmed by them. Sure, the music was clean and free of distortion, and they could play louder than I could stand, but some music (e.g., Springsteen, U2, Prince) just didn't sound as good as I'd hoped. Changing the tweeters has fixed that. I am absolutely delighted! I used REW to take some measurements before and after changing the tweeters. Because I was focused on the tweeters, I measured a range from 4500Hz to 20kHz. The room conditions, equipment, and all parameters were kept the same. I took three measurements before and after changing the tweeters. I "burned in" the new tweeters for about 8 hours before measuring them. This chart shows the average of the measurements, with 1/12 smoothing: Here are my old tweeters: And here are the new SMAHLv2/DE-120 tweeters: I had planned to paint the SMAHL v2 lenses black, but they look so good I may just leave them as they are. Others might not be keen on such a change, but I couldn't be happier. YMMV, but I wanted to share my experience on the forum. I'm grateful to members of the forum ( especially @ClaudeJ1) for making me aware of the SMAHL and to @Dave A for an excellent product.

Today I received a pair of new tweeters from DaveA for my 1986 La Scalas. The new SMAHL v2 lenses and DE-120 drivers will replace the K-77M Ceramic (square magnet) tweeters that are currently in the speakers. New tweeters I had planned on painting the new lenses black, but they look so good that I'm reconsidering that. Old tweeters I plan to run REW before and after installing the new tweeters to see what difference they make.

No photos were posted. Location and photos, please.

I'm about 1/3 of the way through. Today I hope to affix panel 5 (of 10) and cut the speaker baffle. It is my first speaker build. I've found the build instructions to be excellent. Even though I'm just an average woodworker, I'm optimistic that I'll be successful with the project. The adhesive only cures above 19 degrees F so that I'm in a race to see if I can finish the build (in my unheated garage) before the cold weather really sets in. I've actually ordered the parts for 2 THTLPs, but building the second one will have to wait for spring when the weather warms up. Will the results be worth the effort?

Well ... I've been out in the garage building a THTLP. That's a different type of enjoyment. 🙂

Sorry for having to ask about what's already well known ... Dave's tweeter and lens have had much praise on the forums. Where can one find out more about them?

This may be the wrong place to ask but ... Would you please share a bit about what equipment could be used and how one would set up the DSP? I'm especially interested in what one could use (that doesn't cost an arm and a leg) to replace both the input section (streamers, etc.) and the amp section of a receiver. I'd like to experiment with having a DSP replace my crossovers, but I'd like to do so without a spending thousands. I've purchased a UMIK and have played with REW but I'm really just fumbling around with it. If this should be raised in a separate thread, I'll create one.

I didn't think that I could run a DSP with my setup. I would benefit from some education about how they are employed. I drive my La Scalas with a Yamaha R-N803 receiver. My understanding is that, to use a DSP, I'd need to replace my receiver with a separate input stage (tying together a streamer, etc.) and a separate amp. In fact, I thought I might need as many as 3 amps. The signal would be sent from the input to the DSP. The DSP would then go into the amps (one for each pair of tweeters, squawkers, and woofers). The existing networks would be disconnected. The exercise seemed too expensive and disruptive to be attractive. Please correct me where my understanding is faulty.

I enjoy Radio Paradise. It plays a great, eclectic mix and has introduced me to music and artists that I wouldn't have heard otherwise. Because it's listener supported there aren't any commercials.

What would be involved if one wanted to modify an AA to drop the crossover point to 4500 Hz?

Another consideration is your location. I'm in Canada where used La Scalas come to market very infequently. Because of that scarcity, I paid about US$2200 for a pair of 1988 La Scalas in the summer. I replaced the old AL networks (crossovers), with new AAs from Crites. That was about US$500. Simply re-capping the old networks would have been about half the cost. I figure that the materials to repair and refinish my cabinets will end up costing about US$700 by the time I'm finished. I'm doing the work myself, so that there's no cost for labour. All told, my ~US$2200 La Scalas will end up costing about US$3400. I look with some envy at what I see in the "Alerts" and "Garage Sale" sections of the forum. Better speakers than mine come up frequently, and at quite attractive prices.

Welcome to the forum! I'm interested in your perspective. I recently acquired a pair of 1988 La Scalas. They came with AL networks. Because I needed to take the speakers apart to refurbish the cabinets, I figured that, while I was at it, I might as well replace the >30 year old caps. When I looked into the cost, it turned out that buying new caps was more than half the cost of brand new networks from Crites. Not having had experience with La Scalas, I looked to others --- and this forum --- for guidance. The consensus was overwhelming that AA networks were an excellent choice and superior to the AL networks. Consequently, I purchased a pair of new AA networks from Crites. I'm not a particularly discerning listener and I didn't listen to the AL networks for long but I didn't notice much difference from the change in networks. I still have the ALs and plan to swap them in and out to see what differences I can discern. Your experience will make my testing more interesting.

I was able to find the terminal strips I was looking for at an electronics surplus shop. In case the information might be useful for others, I'll share the product information here. They are made by CINCH Connector Division and are called a "barrier block". They are CINCH part number 2-142. Here's the web page that describes them: https://www.belfuse.com/product/part-details?partn=2142 The connector is rated to carry up to 30A and/or 7500 Watts. It can accommodate up to a #10 wire. The data sheet can be found here: https://www.belfuse.com/resources/datasheets/cinchconnectivitysolutions/industrialcinch/ds-CCS-IND-barrier-blocks-142-series.pdf They take an 8-32 machine screw. A screw of >2" will allow me to mount two back to back on either side of a 3/4" panel. They should do nicely for what I need.

Yes. Although I found terminal strips at Parts Express, I didn't find any with an open back.

Thanks for pointing that out, but it has a closed back so that two can't be connected on either side of a panel.

I've been trying to find the terminal strips that connect the inside of the bass bin to the squawker/tweeter "shelf" on my 1988-era La Scalas. I think they're "dual row, 2 pole, open back" terminal strips (or barrier strips). (I don't need them for my La Scalas, they're for a subwoofer I'm building). The terminal strips are mounted back-to-back, one on either side of the wood panel that forms the top of the bass bin. The one on the inside of the bass bin is connected to the woofer. The one on the opposite side of the wood panel (i.e., the bottom of the compartment for the tweeter and squawker) is connected to the network. Each pole on the two terminal strips is connected to its mate on the other terminal strip with machine screws that pass through the wood panel. The tricky bit is that it must be possible to connect the two strips; the ones I've found are solid plastic (not open backs) which makes them unsuitable. I've looked for suitable terminal strips at my local electronics suppliers, but have not been successful. Similarly, I haven't found what I'm looking for at Parts Express. If they're in the Digikey or Mouser catalogues, I haven't been able to narrow the choices down to find what I need.. I'd appreciate it if anyone could point me to where I could find these terminal strips. Thanks in advance.

Thanks. I've been trying to correlate the -80 dB to +16.5dB that my Yamaha R-N803 receiver displays for volume to what I see on my SPL meter. But I haven't been successful. I recognize that the dB numbers shown on the receiver aren't dBA (i.e., sound presure level) but are instead a measure of the receiver's electrical output. I also noticed that a 96 dB range is what woud be expected of a 16 bit value. I expected that max volume would be at 0 dB and that everything lower than that would represent how much attenuation was in force (restriction from full power) so that all numbers would all be negative. But since my receiver goes -80 to +16.5 dB that didn't make sense. I then thought that perhaps 0 dB was set to max power before a certain level of distortion. If that were the case, any numbers above 0 dB would have increasing levels of distortion. That seemed sensible, but I couldn't get the numbers to work. When I deconstruct the receiver's published max power specs at different impedences (e.g., 100W at 8 ohms, 140 watts at 4 ohms) using watts = volts^2/impedence, I get different voltages for the max power (28.3V RMS @ 8 ohms but 25.3V RMS @ 4 ohms). Peak-to-peak that would equate to 40V or 36 V. I had expected that the voltages would have been the same. I had thought I'd hook up the receiver to an 8 ohm resistor and measure the voltage at different volume levels when I input a signal (like a sine wave). However, the biggest 8 ohm resistor I have is rated at 50W which would only be good for 20 volts peak-to-peak (i.e., 14 volts RMS). That won't let me turn up the volume too high on the receiver; in fact I wouldn't even get out of the negative numbers. Any suggestions?

Will you please explain how one would calculate watts used, particularly so that peaks could be included? I'd be interested in finding that out for my system. I've been stymied by the changing mix of frequencies in music, and the different impedances that different frequencies present.

I bought an SVS SB1000 Pro about a month ago and have been very pleased with it.

Will your system support SSDs? The performance difference between HDDs and SSDs is remarkable.