Tizman
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Posts posted by Tizman
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On 1/8/2022 at 8:04 AM, KT88 said:
That today almost every ordinary and many of the more expensive speakers provide a division of the bass and treble connections is good for the perhaps 2% of customers who bi-amp. For the 98% who don't it has rather disadvantages. For manufacturers, it's a catch-22. 35 years ago, bi-wiring terminals were a USP for a few manufacturers. Today many consumers without technical knowledge look during the purchase decision whether the "option bi-wiring" is there or not...Simply: "Is it there"...but not "does it make sense for me".
For some consumers, disadvantage 1 is that manufacturers and Hifi magazine tempt them to spend money on expensive superfluous cables. For many unsuspecting consumers, it must seem like a "norm" or a "standard", with the constant call to supposedly "upgrade". Most manufacturers naturally want to offer this option to customers who want to bi-amp, which is understandable in the competitive market. The final winner is the cable industry.
Disadvantage 2 is a technical one so that the split ports do not sound as good as a single port for the whole freq. region because of the additional contact zones when you connect only one cable.
Here's a tip. When long thin connecting rods between bass and tweeter input are given it has helped me if I tighten the threaded connections very! very! carefully with a pair of combination pliers. Between the pliers and the threaded connection (where you put the bananas in) I take a thin kitchen towel to not scratch anything.The goal is to turn only a little tighter than your fingers can do, but not to break anything. As a result, the treble sounds noticeably silkier when I plug the cable into the bass. The reason will be that the connectors vibrate less and there is less micro-interruption of the contacts.
For connectors that use flat plates between bass and tweeter input I would suggest the same principle. But here I would recommend even more to try a short piece of speaker cable, bare without solder at the ends, instead of the flat thin sheet and tighten it in the same way.
I have had better results when the cable is in the bass clamps. Some companies, like Tannoy, recommend plugging the single run cable into the tweeter. Here I would just try what is better in your case and to your ears.
The completely crazy thing is that many people prefer the sound of bi-wiring only! because for the first time the four contacts are right due to the cable plugs.
The most stupid (or the most clever) thing is that now short pieces of cables are offered that make a divider before the speaker terminals for people without bi-wiring, two inputs and four outputs. This gives you four additional superfluous and quality-reducing contact points.
Such very short distribution cables can cost hundreds of dollars each. So the cable industry also benefits from some consumers with a single run of cable.It seems likely that much of the perceived benefit of bi-wiring is, as you say, due to a better connection being made by the home user when they bi-wire. Perhaps I am missing something, but I can’t see how it would make a difference to attach two sets of wires to your amplifier’s output rather than splitting the power at the speaker. What’s the difference? That said, splitting a crossover into parts and powering each part with a separate amp does make a difference. The source is split so that two stereo amplifiers get the same signal. In the case of a two way, one amplifier is connected to the LF section, and the other amplifier is connected to the HF section. The amplifier responsible for the HF feeds a driver with far lower power requirements. This amplifier is not called upon to power the LF portion of the signal, and therefore HF reproduction is not affected by the work required to power the LF as when one amp feeds both LF and HF. The HF amp has an easier job, and avoids the modulation of its output by the needs of the LF section. This is based upon my online research a few years back. Basically, I was trying to figure out if a tube amp output transformer would be impacted by receiving the full signal from the source, and amplifying that signal into a passive high pass filter that kept the LF frequencies from reaching the driver. This was in order to build an HF tube amp with smaller, less expensive output transformers that also, in my experience, produce better quality HF response than that from large OPTs. The answer I got at the time was that if an amp powers an HF crossover, the LF portion of the signal that doesn’t draw power also doesnt affect the amps performance any more. It’s effectively not there. This may be entirely incorrect, but it’s what I got out of my questions at the time.
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Using two amplifiers into a divided passive crossover, with the bass portion separate from the mid and tweeter section, has obvious audible benefits. When I do this, I use an RCA splitter on my source so that I can plug into two separate power amps. One amp powers the bass portion, and the other amp powers the mid and treble portion in a three way, or the single HF driver in a two way. At least one, but ideally both amplifiers should have a volume control. Using two amplifiers instead of one confers multiple benefits. This makes it possible, for example, to use a 45 amp on the highs, and a push-pull EL34 amp on the lows. Obviously, it depends on the existing crossover as the crossover needs to be split, but that should be doable in many cases using the parts in the existing crossover. For most of the Klipsch crossovers I’ve seen, it’s pretty easy.
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On 12/12/2021 at 7:56 AM, Deang said:
You're saying you changed out the capacitors for new ones?
Are those old autoformers really T2A's?
Yes, T2As. The crossovers are newer than the bass bins. I replaced the capacitors for new ones of the same values.
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I ended up with the stock AA crossover values for the capacitors. The KHorns sound muddled overall as compared to my La Scalas. I feel that the midrange could be louder as compared to the bass. Perhaps I'll try changing the autoformer tap so that the squawker is 3 DB up. Something is off. The KHorn has deeper bass, more bass and better quality bass, but the La Scalas sound much more cohesive in the higher frequencies.
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Leaving the speakers playing music overnight greatly improved the sound. They sound much better. The ‘74 La Scalas still sound more cohesive in comparison, and more “real”. The Khorns have much more and better bass. Perhaps I’m just not used to the more full range character of the Khorns? I haven’t tried going back to the original 2uF/.245mH/2uF tweeter crossover section. I am using the higher Q 2.2uF/.16mH/6.7uF recommended by ALK. Any opinions on this modification to the AA?
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On 11/27/2021 at 7:14 AM, KT88 said:
Perhaps the lascala is simply better than the klipschorn when it comes to connecting the mids to the bass.
I suggest the following test: Build all the parts from one of the Lascalas, squaker, xover and tweeter into one of your Khorns.
Then you can compare...
1) Khorn original against Khorn with Lascala parts. If you hear differences, there is potential here.
2) Khorn (with Lascala parts in midrange, treble and xover) against the second Lascala that you have not dismantled.
If you still hear a difference here basically in the same way you have not liked and mentioned as such before then it is 100% due to the fact that they are different bass horns. There are no other influences.
If you still don't like what the Klipschhorn reproduces in it‘s midrange and treble compared to the Lascala, then it's probably the worse connection in the 400 Hz region of the Khorn from bass to midrange (which also affects the perception of treble).
BTW are both, the Lascala and Khorn the first of their kind which you experience?
I have three pairs of La Scalas. My daily drivers are a
pair of ‘74s with AA networks. I also have two pairs from 1989 with AL-3 networks. I prefer the ‘74s. The Khorn is my first. I hope it’s not an issue with the match between bass bin and the HF section. I have switched the tweeter portion of the crossover from the original 2uF/.245mH/2uF to 2.2 uF/.16mH/6.7uF on the original board, and have an extra outboard tweeter section that uses the original values to compare. I am currently burning in the speakers as they haven’t been used for a long time. This may be part of the problem.
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16 minutes ago, captainbeefheart said:
Yep, high powered, high distortion at high frequencies when clipping, and unstable oscillations started blowing much more tweeters vs tube predecessors.
Well thank goodness it’s all tubes for me. I suppose the protection diodes can be safely omitted in my case.
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8 minutes ago, PrestonTom said:
You do realize that AA crossovers are NOT 1st order (the Type A were however). Maybe this was a typo. The tweeter filter is 3rd order. I hope no one gets confused about this. However, I do agree that the filter on the tweeter may not be that critical since there is so little energy (from program material) up that high anyway.
The entire crossover is not first order, but the crossover to the woofer is just a 2.5mH inductor. Isn’t that by definition first order?
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1 hour ago, captainbeefheart said:
Take a look at the third picture down of the tweeter frequency response I posted 4 posts ago, you can easily see this bump at 9kHz. I can simulate whatever you want to try so you can see what will happen. I will add an inductor into the simulation where you suggest to see what happens.
That would be great. Thanks.
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44 minutes ago, henry4841 said:
Would be close enough in my world. AA's are 1st order crossovers where values are not that critical. I noticed that CBHeart wants your old square caps. Technicians know film caps in crossover networks, and for that matter old electronic gear, rarely just fail and hold their values pretty good. Not a hard working electronic piece in a crossover network. Unless they are leaking probably still good. That being said they are sure ugly and I would probably replace just because. I restore old equipment and just replace the electrolytics and leave the films alone unless they are known to fail such as really old tube electronics. The theory being destroying the old sound many enjoy. I really do not know any restorer of old equipment either in person or online sources that replace film caps in old equipment. I cannot see why crossover networks would be any different except from those trying to sell such. It is a crap shoot if replacing caps will be an improvement. Many claim too bright after doing so.
I have limited measuring equipment, so I’m not certain if my “close to spec” measurements are close enough. I am currently using a DMM, an LC meter, and a cheap LCR-T4 component tester. My Klipschorns definitely have potential. Their bass response is much deeper and better sorted than my La Scalas. That said, they don’t sound right overall. The speakers don’t image well and sound confused in the treble as compared to my La Scalas. Something is amiss. Old film caps that I have measured with my limited equipment have been mostly good. If the caps are good, what is causing the problem? The drivers seem to be in good shape, and are wired properly. The speakers are in the corners, and the corners are two block walls. The room is partially treated with sound absorbing panels and sounds good with the La Scalas. If not the caps, what?
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John A has posted that including a .35 to .4mH inductor between the T2A and the squawker helps to take out a hump in the K-77 squawker’s response at 9K Hertz. Is this something I should include?
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1 hour ago, captainbeefheart said:
You would have to place them in series to get the inductance you want, they are the reciprocal of a capacitor remember. You would have to measure/calculate the DCR of them all in series to get an idea if it's worth it.
Here is my XO, my meter reads .4 ohms and that is with the cheapo long test probe cables which most likely add .1 to the total, so in actuality the stock core inductor is more like .3 ohms.
I am using extra long probes that add .2 Ohms or so, so I’m probably actually at .8 Ohms. That is .5 Ohm above the stock inductor. The other associated issue with the extra .5 Ohms is that I use mostly single ended triode connected tube amps, which have a high output impedance. Perhaps not a great idea. I’m not too concerned about the losses created by the additional .5 Ohms, as the Klipschorns in my room are a bit bass heavy, but the decreased damping might be an issue. I’ll try both and see.
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I also have several .51mH air core inductors that I could parallel to get a .255mH value. Is that close enough for replacing the .245mH value in the schematic?
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4 minutes ago, RandyH said:
why even bother messing with the old board , it may have a Collector Value on the Garage Sale , you can build a new crossover on a wood board using the parts you have -
Sounds like a plan.
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11 minutes ago, captainbeefheart said:
Check the DCR of that air core inductor and compare it to the stock inductor, I highly doubt you are bringing the stock one into core saturation which is the only benefit of having an air core inductor, no core interaction. The air core will add resistance into the woofer circuit lowering your damping factor and increasing the loss across it. They make super core inductors with extremely low DC resistance that won't saturate the core, I would choose those over an air core any day of the week.
I checked the resistance across the 2.4mH inductor with a DMM set to resistance, and it is 1 Ohm. It is reasonably beefy.
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9 minutes ago, captainbeefheart said:
Tizman- if you do end up replacing the capacitors please message me as I would like your old ones as spares for my original crossovers. I like the Aerovox caps. The 13uF is an odd value to find today so I wouldn't mind some spares if mine go south. At the very least I will spend the time to see if they are worth keeping as backups instead of just blindly throwing them in the trash.
I’m going to keep the original caps so I can return the crossover to original for any future sale. I will let you know if I change my mind though.
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Thanks for all the replies. I’m going to replace all the caps, check for the brass screw and keep the rest for now. I have a bunch of Solen caps in the correct values, including 13uF, taken from a stack of three way crossovers I bought from a theatre redo. I also have a bunch of inductors including 16 gauge 2.4mH ones. Would these be close enough to replace the 2.5mH ones in the AA?
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Hi All. I picked up a pair of Klipschorns! They are bass cabs from the 50s with K-33-E in them, k-400 horns with K-55-V drivers and square magnet K-77 tweeters. They sound a little off as compared to my La Scalas and sound flat with fuzzy imaging. I was about to switch out the capacitors, but measured the ones that could be measured in circuit, and they measured reasonably well. I haven’t seen these caps before in a Klipsch crossover so I was hoping on getting your opinions on switching them and the need for it. Please have a look at the attached photos.
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On 9/27/2021 at 11:34 AM, Panelhead said:
I will be pulling the crossovers out of mine soon. Can trace it out.
These latest crossovers are constructed with very high quality parts. Nothing like motor run caps of old. Are you hoping to upgrade yours or diy one?
Just wondering if you took them out and had a chance to look at them. I read somewhere that they don't use an autoformer anymore. Any details you may have would be much appreciated as I can't find anything about them online.
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7 hours ago, RandyH001 said:
no-all it does is aid the stock magnet to a slightly tighter bass -
Thanks!
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For the purposes of speaker design, are the effects on the driver parameters significant enough to keep me from using the normal K-48 parameters?
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8 minutes ago, RandyH001 said:
a magnet was added on top of a k45 , by drilling 3 holes , simple answer
Interesting. What impact to parameters is normally expected when adding a magnet like this? My intended use is in a large horn subwoofer.
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Hi All. I picked up this woofer last week and was hoping someone could help me identify it. It came with a couple of drivers that the seller identified as being Klipsch in origin. The lot included a K-48-KT. This driver has a cast frame and looks most like a K-45. The ribbed spokes on the basket are the same, and the rear vent and cone look the same. The big difference is the extra magnet attached to the back. Any insight would be much appreciated.
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Here are a couple of REW screenshots comparing the bass response of my La Scalas to my two ways with Eminence Kappa 15C in a Peavey FH-1. The two speakers were measured in the same position with the microphone at the same height and pointing at the mid horn for the La Scalas, and the HF horn for my two ways. The microphone was 4' from the speakers.
I understand that the 15C gives up a few DB at the bottom in exchange for better performance at the top of its range, but this measurement shows a drop of more than a few DBs. Subjectively, my two way is obviously bass shy compared to the La Scala. My question is whether this is normal, or not? Is this due to my improperly installing the 15Cs in the cabinets, or is this the missing "few DB at the bottom" that is normal? Any insight would be much appreciated.
La Scala is red and 15C in FH-1 is green.
Bi-wiring La Scala's
in Technical/Restorations
Posted
The explanation I got was that because the crossover doesn’t pass the LF portion to the speaker, the current draw that would otherwise happen isn’t there anymore. In other words, the driver is the load, and if the driver isn’t drawing current for the LF that is filtered out by the crossover, the amp doesn’t need to supply the power to the missing LF portion. Again, this information is based on my questions about using small output transformers on an amp built for just the HF section of a horn two way.
I currently own three electronic crossovers. I would love to use them, but I have found that every one adds too much noise for my very quiet listening room, and that passives just sound better. I wish it wasn’t so, because using an active crossover would simplify things greatly, but it is.