LaScala for this room

[svberger]

I'm listening to the opening track of this now, fairly loudly, and not a trace, A TRACE, of distortion other then what Dave Rempis chooses to play. A better testament you won't have from me today.

 

 

 

[KT88]

1 hour ago, svberger said:

1.5 watts is fairly low in my estimate, and even for owner of a super efficient speaker like the LS one has to think that reaching that amount of gain would not be unusual. And therefore believing that distortion  could happen at a gain even lower then that is not asking for a lot. And as you point out, one's ears should quite easily be able to provide evidence as to that. Mine did.

 

Not to get too technical but just to be clear. When you say 2 watts, I assume you mean 2 watts in total that someone sends out of the amp. And yes, that is quite loud with a Lascala. But you are right, there are situations where someone sends more, e.g. in the peaks 5 watts or more into a Lascala. 10 watts would already be a doubling of the volume compared to 1 watt, which means sometimes hurting 110dB for the ear instead of the loud 104dB at one watt.

But to clarify, we are talking about the diodes only for the portion of the power that is converted at the tweeter.

In the old thread you linked, the ratio of the power distribution is very clearly described by a member:

 

Perfectly understandable, maybe this will give you and understanding of how the power is divided.

Your speaker is divided into 3 sections Woofer Mid and Tweeter, the woofer uses 85% of your power, the mid 13% and the tweeter 2% these numbers are just rough guesses to give you and idea.

For 50 watts in, the woofer is using 42 watts, the mid is using 6.5 watts and the tweeter uses 1watt. This is just a rough breakdown.

Dave

 

Even if the numbers of the member are only estimates, it is in principle true.

What does that mean for 2 watts from the amp into the Lascala. This means that at 2 watts in total the tweeter gets just 0.04 watt. The xover takes care of this, it filters the high-energy low tones and ensures that the tweeter does not get them.
So we are talking about 0.04 watt for the tweeter in our sound impression. 
But since already at this power (and quieter) the sound impression is different when you listen with or without diodes, it means that the diodes "in principle" cause something negative to the sound. I think there are even two types of influence. The one influence is the intended one, when from 1.5 watt on ONLY at the tweeter distortions occur as a side effect of the protection. The other influence is the principle behave of the diodes, which can make itself negatively noticeable already with quiet signals. Kind of like a "carpet" of irritations.

Sorry I did not want to go on longer on the subject and not bore you but it is important to distinguish between 2 watt in the whole and 2 watt on the tweeter alone.

[svberger]

22 minutes ago, KT88 said:

 

Not to get too technical but just to be clear. When you say 2 watts, I assume you mean 2 watts in total that someone sends out of the amp. And yes, that is quite loud with a Lascala. But you are right, there are situations where someone sends more, e.g. in the peaks 5 watts or more into a Lascala. 10 watts would already be a doubling of the volume compared to 1 watt, which means sometimes hurting 110dB for the ear instead of the loud 104dB at one watt.

But to clarify, we are talking about the diodes only for the portion of the power that is converted at the tweeter.

In the old thread you linked, the ratio of the power distribution is very clearly described by a member:

 

Perfectly understandable, maybe this will give you and understanding of how the power is divided.

Your speaker is divided into 3 sections Woofer Mid and Tweeter, the woofer uses 85% of your power, the mid 13% and the tweeter 2% these numbers are just rough guesses to give you and idea.

For 50 watts in, the woofer is using 42 watts, the mid is using 6.5 watts and the tweeter uses 1watt. This is just a rough breakdown.

Dave

 

Even if the numbers of the member are only estimates, it is in principle true.

What does that mean for 2 watts from the amp into the Lascala. This means that at 2 watts in total the tweeter gets just 0.04 watt. The xover takes care of this, it filters the high-energy low tones and ensures that the tweeter does not get them.
So we are talking about 0.04 watt for the tweeter in our sound impression. 
But since already at this power (and quieter) the sound impression is different when you listen with or without diodes, it means that the diodes "in principle" cause something negative to the sound. I think there are even two types of influence. The one influence is the intended one, when from 1.5 watt on ONLY at the tweeter distortions occur. The other influence is the principle behave of the diodes, which can make itself negatively noticeable already with quiet signals. Kind of like a "carpet" of irritations.

Sorry I did not want to go on longer on the subject and not bore you but it is important to distinguish between 2 watt in the whole and 2 watt on the tweeter alone.

Yes thank you.  Makes perfect sense.

[captainbeefheart]

I would look at it in terms of voltage.

 

The zeners are 1N3996 which have a reverse breakdown voltage of 5.1v and a forward biased drop of .637

 

Add them together and that gives us a peak waveform of 5.737 volts allowed to the tweeter. Anything over that will be clamped off. Transients like signals from cymbols are usually short duration so it's possible during loud listening you could have some content clamped off at 5.737 volts that may not necessarily burn out a tweeter. I believe this is why people can hear a difference when removing the diodes and their tweeters didn't melt away from doing so.

 

Thinking in terms of rms power change the 5.737 peak to rms = 4

 

4² / 8 = 2 watts

 

The tweeters are protected from anything over 2 watts of power or any signal over 5.737v peak is clamped, however you want to look at it.

[KT88]

36 minutes ago, captainbeefheart said:

I would look at it in terms of voltage.

 

The zeners are 1N3996 which have a reverse breakdown voltage of 5.1v and a forward biased drop of .637

 

Add them together and that gives us a peak waveform of 5.737 volts allowed to the tweeter. Anything over that will be clamped off. Transients like signals from cymbols are usually short duration so it's possible during loud listening you could have some content clamped off at 5.737 volts that may not necessarily burn out a tweeter. I believe this is why people can hear a difference when removing the diodes and their tweeters didn't melt away from doing so.

 

Thinking in terms of rms power change the 5.737 peak to rms = 4

 

4² / 8 = 2 watts

 

The tweeters are protected from anything over 2 watts of power or any signal over 5.737v peak is clamped, however you want to look at it.

CBH you also have Lascala with AA xover. I would be very happy and maybe other member also if you would join the experiment once soft to medium loud to hear without the diodes in the circuit?

Your equation is certainly correct. But I am interested in the phenomenon that even at much quieter SPL the influence of the diodes is audibly negative to my ears.

[captainbeefheart]

3 minutes ago, KT88 said:

CBH you also have Lascala with AA xover. I would be very happy and maybe other member also if you would join the experiment once soft to medium loud to hear without the diodes in the circuit?

Your equation is certainly correct. But I am interested in the phenomenon that even at much quieter SPL the influence of the diodes is audibly negative to my ears.

 

I'll do one better.

 

I'll hook up a distortion analyzer to the tweeter and see if there is any difference with them in or out. I think I'll measure with the actual K77 hooked up and then if I reach volumes where it's sounding annoying I'll also check with a resistor load.

 

 

[KT88]

9 minutes ago, captainbeefheart said:

 

I'll do one better.

 

I'll hook up a distortion analyzer to the tweeter and see if there is any difference with them in or out. I think I'll measure with the actual K77 hooked up and then if I reach volumes where it's sounding annoying I'll also check with a resistor load.

 

 

From a technical point of view it may be a better in the sense of more objective approach what you suggest but please share also the experiment of listening.

 

I believe there is something influencing the sound re the diodes. Is it possible that after all the decades a kind of resistance has grown to the diodes? Or whatsoever which makes a difference when listening with or without them?

Here we are at the interesting point if measurements are as good as our ears/listening.

[svberger]

Listening is where it's at. If I can hear how significantly the difference, dare I say improvement is, I would be shocked if anybody could not.  It's dramatic.

[captainbeefheart]

3 minutes ago, KT88 said:

From a technical point of view it may be a better in the sense of more objective approach what you suggest but please share also the experiment of listening.

 

I believe there is something influencing the sound re the diodes. Is it possible that after all the decades a kind of resistance has grown to the diodes? Or whatsoever which makes a difference when listening with or without them?

Here we are at the interesting point if measurements are as good as our ears/listening.

 

The resistance in the diodes changes dynamically depending on the amount of current flowing. No current will flow through the diodes unless you reach 5.737v peak, once this happens and current starts to pass the diode impedance starts decreasing as current is increasing. There are graphs in the datasheet that show current vs impedance for the specific diode.

 

When you are under 5.737v peak the dynamic impedance of the diodes is infinitely open.

[captainbeefheart]

2 hours ago, svberger said:

Listening is where it's at. If I can hear how significantly the difference, dare I say improvement is, I would be shocked if anybody could not.  It's dramatic.

 

But measuring answers the reasons why it sounds different which I just did the testing and can prove the diodes effect the sound.

 

Calculations show it should clamp at 5.737v which the testing confirms. BUT, there is a big difference in distortion below that as soon as you reach 4v peak. At 1 watt, which is quite a bit into the tweeter the distortion is the same, the instant you get to around 4v peak distortion starts to drastically increase with the diodes in circuit, out of circuit it stays clean. That is not the intention of that circuit, it's not suppose to do anything or effect the sound until you reach the peak clamp voltage and then it cuts the waveform right off as it should, the distortion is obviously unintentional and I am not sure if Klipsch even knows about it.

 

I will start a new thread to post my findings and discuss this further.

[svberger]

5 minutes ago, captainbeefheart said:

 

But measuring answers the reasons why it sounds different which I just did the testing and can prove the diodes effect the sound.

 

Calculations show it should clamp at 5.737v which the testing confirms. BUT, there is a big difference in distortion below that as soon as you reach 4v peak. At 1 watt, which is quite a bit into the tweeter the distortion is the same, the instant you get to around 4v peak distortion starts to drastically increase with the diodes in circuit, out of circuit it stays clean. That is not the intention of that circuit, it's not suppose to do anything or effect the sound until you reach the peak clamp voltage and then it cuts the waveform right off as it should, the distortion is obviously unintentional and I am not sure if Klipsch even knows about it.

 

I will start a new thread to post my findings and discuss this further.

I'm sorry I didn't mean that testing is useless or I'm not interested in it, rather that in this instance one should be able to hear the positive results without much effort. In my experience, testing in audio will often provide clear cut answers that the ears(at least mine) can't decipher.

 

My understanding is the PWK put the protection in place when solid state amps became big and started blowing tweets left and right and was costing the company lots of $$ to replace under the life long warranty. Evidently making sure it didn't affect the sound took a backseat to saving money.

 

[KT88]

38 minutes ago, captainbeefheart said:

 

But measuring answers the reasons why it sounds different which I just did the testing and can prove the diodes effect the sound.

 

Calculations show it should clamp at 5.737v which the testing confirms. BUT, there is a big difference in distortion below that as soon as you reach 4v peak. At 1 watt, which is quite a bit into the tweeter the distortion is the same, the instant you get to around 4v peak distortion starts to drastically increase with the diodes in circuit, out of circuit it stays clean. That is not the intention of that circuit, it's not suppose to do anything or effect the sound until you reach the peak clamp voltage and then it cuts the waveform right off as it should, the distortion is obviously unintentional and I am not sure if Klipsch even knows about it.

 

I will start a new thread to post my findings and discuss this further.

Thanks for your efforts, CBH. Regardless of the obviously lower than intended threshold where distortion appears is there also a negative  influence of sound when we focus on even lower voltage?

 

Another point, we want to have both benefits, a protection of the tweeter especially when a vintage item would not get an equal replacement re the coil/diaphragm and also we like a clean and nice sound as it would be without the diodes. Is it possible if someone wants to have a good sleep that the tweeters are protected in another way by replacing the diodes as a safety insurance with a fuse in series to the tweeter? Perhaps not at the point were the voltage is low (after both caps and the coil) but e.g. directly after the squaker before the caps and coil of the tweeter? In this case a fuse could perhaps react to higher voltage before the tweeter should get into danger? 

But I do not know if a fuse in series also would have a negative influence to the sound at all?

[captainbeefheart]

44 minutes ago, svberger said:

I'm sorry I didn't mean that testing is useless or I'm not interested in it, rather that in this instance one should be able to hear the positive results without much effort. In my experience, testing in audio will often provide clear cut answers that the ears(at least mine) can't decipher.

 

My understanding is the PWK put the protection in place when solid state amps became big and started blowing tweets left and right and was costing the company lots of $$ to replace under the life long warranty. Evidently making sure it didn't affect the sound took a backseat to saving money.

 

 

No worries, I know what you were saying. I get it that also many don't really care why it sounds better, just that it sounds better and they are happy with the results. I was just merely stating that I like measuring things for a why to quantify why it sounds different.

[svberger]

I have to wonder how many folks have tried all kinds of things to tame AA crossover  LS's,   from homemade remedy's to spending in some cases hundreds of dollars, or more, and yet have never tried this one simple little tweak?

 

I bet it's a lot.

[Islander]

My 1974 La Scalas have AA crossovers, and the protection diodes are in place and hopefully doing what they should, and not doing anything they shouldn’t.  All I’ve done to the crossovers was to replace the 32-year-old tin can caps in my Scalas with new Sonicaps.  I was immediately pleased by the new brightness and clarity that I was hearing.

 

As for the midrange “shoutiness’, that was the one thing that disappointed me when I first hooked up the speakers.  They didn’t have the sweet and clear sound that I was expecting.  Prior to the purchase, the only listening available was a few songs in the crowded store.  I mean really crowded.  There were no aisles as such, so you had to pick your way through all the speakers and electronics stacks to get to the counter at the back of the small shop.  It’s called Q-Electronic Services, and has since been relocated to a much larger shop on Douglas Street, the Main Street of Victoria, like Yonge Street in Toronto.

 

For me, the simplest way to tame the squawker was to add three layers of thin and stretchy black grille cloth to the inner side of the squawker’s mounting board, so the K400 horn now speaks through that.  I had no suitable gear to measure sound quality, other than level, but listening tests showed clearly that this worked.  I experimented with one, two, three, and four layers, and settled on three as giving me clear and clean sound, without having the sense that the person yelling at you was so close that you almost expected to be hit with his saliva.  That was my initial impression of the speakers, and taming it made them very pleasant to listen to, which they had not been at first.

 

Now those La Scalas are my Surround speakers, and when I’m listening at low volume late at night, with the loveseat fully reclined and the receiver set to 9-channel/all-channel stereo, the effect is very good.  Because of the presence of a baseboard heater on one side and a wood stove on the other side, the speakers couldn’t be located all the way at the side walls.  Instead, each La Scala is located about 4-5 feet/1.3-1.5 metres away from my head.

 

Since they’re much closer than the main speakers, about 1/3 of the distance from the mains, at low volume they dominate, which is just fine.  In that situation, they’re like the world’s biggest and most comfortable headphones.  That works for me.  The rest of the time, they complement the main speakers when I’m watching a show or movie that has surround encoding and the receiver is set to decode them.

 

Of course, for serious stereo listening, only the main speakers, the JubScala IIs, and the subwoofers are active.  This system does it all for me, and I feel lucky to have it.

[svberger]

Unfortunately as we’ve been discussing all day those diodes are doing things that they shouldn’t while most likely not really needed in pretty much all instances unless an overzealous use of gain is employed. Everything I’ve read over the last few days has provided much anecdotal evidence that there has been no failures of tweeters in these speakers caused by removing the diodes. Obviously if the speakers are being used as part of a powerful surround sound rig it is probably just as well leaving the diodes alone but as the main speakers in a 2 channel set up with quality amplification and judicial use of gain I would argue that the positives far outweigh any possible negatives. 

[Islander]

 

14 hours ago, svberger said:

Unfortunately as we’ve been discussing all day those diodes are doing things that they shouldn’t while most likely not really needed in pretty much all instances unless an overzealous use of gain is employed. Everything I’ve read over the last few days has provided much anecdotal evidence that there has been no failures of tweeters in these speakers caused by removing the diodes. Obviously if the speakers are being used as part of a powerful surround sound rig it is probably just as well leaving the diodes alone but as the main speakers in a 2 channel set up with quality amplification and judicial use of gain I would argue that the positives far outweigh any possible negatives. 

 

You may well be right.  I get the impression that tweeter failures were occurring at very high volume levels, like in dance clubs, or when music was played that somehow demanded top volume, like Pink Floyd or Boston.  And of course there’s that other situation, where the ill-informed music fans want max volume while vacuuming, or while they’re outside washing the car.

 

The very directional nature of these speakers means that when you’re not in front of them, like in another room, the volume drops off dramatically.  If I’m just two rooms away from the stereo, like in the kitchen preparing some food, and I use the Yamaha audio control app to bring up the volume to a pleasant volume level, so that I can make out every word of the lyrics over the sound of the microwave, or when water is running in the sinks, I get a surprise when I get back in front of the speakers.

 

When I return to the living room, with the stereo set to give enjoyable volume in the kitchen, IT’S LOUD in there!  There are some omnidirectional speakers that will “fill your home with music”, but these aren’t them.  They present music to the person who’s sitting in front of them, unaffected by reflections from the walls in the room.  Does that mean that Heritage Series speakers are for music purists, who want to hear their music as it was recorded, without distortion, with nothing added to or subtracted from  their music?  Yes, actually.  There’s a quote by Paul Klipsch in which he mentions that.  One of the members uses that quote as his signature line in his posts.  I don’t remember it exactly, but it goes something like “99% of people can’t tell the difference between good and bad sound.  I make my speakers for that 1% who can tell, and who are willing to buy these expensive speakers.”  If I come across it, I’ll put in the exact quote later.

 

Almost forgot:  PWK originally designed his first speaker, the Klipschorn, to accurately deliver the sound of a symphony orchestra at full volume, driven by a low-power tube amp.  Later, when transistor power amps became widely available, often with 100 watts per channel, tweeters started blowing, leading Paul to grumble about 100-watt “stoves” that were blowing his tweeters.  The Pro side of the company ran into a similar problem with concert hall sound systems.

 

The pro sound technicians weren’t familiar with the very high sensitivity of Klipsch speakers, so they’d hook them up to the power amps they would normally use.  The result was more blown speakers, sadly.

 

The thing is, just paying attention to the volume control and the sound of the speakers is all you need to do.  There’s a number of Forum members who use high-power amplifiers with Heritage and Pro Theater speakers, with no problems.  My main speakers are bi-amped, and driven by a pair of 500 Wpc 2-channel dual-mono power amps.  That means 1000 watts per channel, with 500 watts being available to the tweeters, and 500 watts to the woofers.

 

Sixteen years later, the system is fine.  I mostly run it at low volume, and on the rare occasion when I want to show its very high possible volume, the sound reaches painful level way before the amps approach their maximum output, so I don’t know how loud it actually goes.  It’s loud enough for me, that’s for sure.

 

Why use these high-powered amps, when most of their power goes unused?  I like them.  That’s all.  They have clear sound that lets you hear every instrument, all the way to the back of the stage.  Their wattage is almost irrelevant, but the high amount of headroom means that every sound is reproduced at its correct relative volume, no matter how low or how high the volume setting.  They were Yamaha’s statement amp, so there was only one model, and it was designed to be able to drive any speaker, of any kind of sensitivity, probably from 85 dB/W/m. to 108 dB/W/m.  Okay, there weren’t many, if any, 108 dB speakers when the MX-D1 amps came out in 2005, but if I ever get a pair of the new Jubilee speakers, I know I’m all set, apart from needing a home with bigger rooms.

[henry4841]

My '86 LaScala's came from the factory without diodes. I will assume they were out of them when my crossovers were built. I have never blown a tweeter myself but years ago my teenage sons did. Replaced under warranty. To prevent it happening again I fused my speakers and have never had a problem again. If fuses have any effect on sound I did not, have not heard any difference. Knowing a little electronics I am sure fuses, being smaller then the wire connecting the speakers does have some effect, damping factor maybe, but the sacrifice is worth the cost for me protecting my tweeters. Of course someone can always replace the tweeters with some of Crites which are rated inline with the mid driver if so inclined. Another reason for fuses with me is I am always replacing and building amplifiers and fuses are good insurance as well for what I do. Many speakers come from the factory with fuses installed. I think the instructions that came with my speakers recommend 1 1/4 amp slow blow fuses but those are kinda hard to find so I just use 1 amp ones. 

[KT88]

3 hours ago, Islander said:

 

 

You may well be right.  I get the impression that tweeter failures were occurring at very high volume levels, like in dance clubs, or when music was played that somehow demanded top volume, like Pink Floyd or Boston.  And of course there’s that other situation, where the ill-informed music fans want max volume while vacuuming, or while they’re outside washing the car.

 

The very directional nature of these speakers means that when you’re not in front of them, like in another room, the volume drops off dramatically.  If I’m just two rooms away from the stereo, like in the kitchen preparing some food, and I use the Yamaha audio control app to bring up the volume to a pleasant volume level, so that I can make out every word of the lyrics over the sound of the microwave, or when water is running in the sinks, I get a surprise when I get back in front of the speakers.

 

When I return to the living room, with the stereo set to give enjoyable volume in the kitchen, IT’S LOUD in there!  There are some omnidirectional speakers that will “fill your home with music”, but these aren’t them.  They present music to the person who’s sitting in front of them, unaffected by reflections from the walls in the room.  Does that mean that Heritage Series speakers are for music purists, who want to hear their music as it was recorded, without distortion, with nothing added to or subtracted from  their music?  Yes, actually.  There’s a quote by Paul Klipsch in which he mentions that.  One of the members uses that quote as his signature line in his posts.  I don’t remember it exactly, but it goes something like “99% of people can’t tell the difference between good and bad sound.  I make my speakers for that 1% who can tell, and who are willing to buy these expensive speakers.”  If I come across it, I’ll put in the exact quote later.

 

Almost forgot:  PWK originally design gamed his first speaker, the Klipschorn, to accurately deliver the sound of a symphony orchestra at full volume, driven by a low-power tube amp.  Later, when transistor power amps became widely available, often with 100 watts per channel, tweeters started blowing, leading Paul to grumble about 100-watt “stoves” that were blowing his tweeters.  The Pro side of the company ran into a similar problem with concert hall sound systems.

 

The pro sound technicians weren’t familiar with the very high sensitivity of Klipsch speakers, so they’d hook them up to the power amps they would normally use.  The result was more blown speakers, sadly.

 

The thing is, just paying attention to the volume control and the sound of the speakers is all you need to do.  There’s a number of Forum members who use high-power amplifiers with Heritage and Pro Theater speakers, with no problems.  My main speakers are bi-amped, and driven by a pair of 500 Wpc 2-channel dual-mono power amps.  That means 1000 watts per channel, with 500 watts being available to the tweeters, and 500 watts to the woofers.

 

Sixteen years later, the system is fine.  I mostly run it at low volume, and on the rare occasion when I want to show its very high possible volume, the sound reaches painful level way before the amps approach their maximum output, so I don’t know how loud it actually goes.  It’s loud enough for me, that’s for sure.

 

Why use these high-powered amps, when most of their power goes unused?  I like them.  That’s all.  They have clear sound that lets you hear every instrument, all the way to the back of the stage.  Their wattage is almost irrelevant, but the high amount of headroom means that every sound is reproduced at its correct relative volume, no matter how low or how high the volume setting.  They were Yamaha’s statement amp, so their was only one model, and it was designed to be able to drive any speaker, of any kind of sensitivity, probably from 85 dB/W/m. to 108 dB/W/m.  Okay, there weren’t many, if any, 108 dB speakers when the MX-D1 amps came out in 2005, but if I ever get a pair of the new Jubilee speakers, I know I’m all set, apart from needing a home with bigger rooms.

I don‘t remember which page but someone already mentioned in this thread that the protection of the tweeter took place not only because of the rising power capabilities of the then new sand amps but also because some models had no relays or other protection when switching on or off. Regarding a tube amp most failures of the design are shielded by the output transformer, such as voice coil killing DC or super sonic oscillations

 

the tubes must first warm up after being switched on. Nevertheless, I've also had nasty bangs in my speakers when the MC275 a power tube blew up when switching on.

One thing surprises me. Not so very few people here like to use the even older Xover Type A? (I don't like the sound that much except maybe with SET listening very softly but that's not the point now).

There are even Type A where the crossover frequency was lowered to 4500 Hz? Strange. With the Type A there is a funny fact. No one complains about the lack of protection when there is no protection. A little paradoxical, don't you think?
When comparing the schematics, it becomes clear that there are no diodes on the Type A (the two strange things that are drawn on the Type AA xover as the last across before the tweeter).
In addition to the worse protection: of Type A as you can see the Type A crossover is a 6 dB design with shallow slope (ok the voice coil must be added). So there is only one cap in series before the tweeter. This means that low tones that can damage the tweeter still remain comparatively loud and thus can damage the tweeter more.

Type AA instead has an 18 dB slope. You see in the high frequency tract a cap in series, then a coil in parallel and a second cap in series behind the coil towards the tweeter. This protects the tweeter disproportionately stronger already without using diodes. 

 

And this is the reason of my post, Type AA already does a lot for the protection already without diodes. Basically, I would argue that if anything in a living room environment, mostly power-on pops and power-off pops can cause damage, not the normal loud listening even not the occasions of party loud dance music listening.

With such an unprotected transistor amp unfortunately every time when switching on or off it bangs, with a tube amp it is very very rare if about a short circuit happens and if the fuse was too slow.

 

 

 

 

 

 

 

[KT88]

1 hour ago, henry4841 said:

My '86 LaScala's came from the factory without diodes. I will assume they were out of them when my crossovers were built. I have never blown a tweeter myself but years ago my teenage sons did. Replaced under warranty. To prevent it happening again I fused my speakers and have never had a problem again. If fuses have any effect on sound I did not, have not heard any difference. Knowing a little electronics I am sure fuses, being smaller then the wire connecting the speakers does have some effect, damping factor maybe, but the sacrifice is worth the cost for me protecting my tweeters. Of course someone can always replace the tweeters with some of Crites which are rated inline with the mid driver if so inclined. Another reason for fuses with me is I am always replacing and building amplifiers and fuses are good insurance as well for what I do. Many speakers come from the factory with fuses installed. I think the instructions that came with my speakers recommend 1 1/4 amp slow blow fuses but those are kinda hard to find so I just use 1 amp ones. 

I had this idea told yesterday here re the fuses instead of diodes for the home situation. Good to know that you have realized this solution, a true teenager protection😀 Where have you placed the fuse? in front of the total network or in front of the tweeter path within the network?

 

But I do not get hysterical without fuse (and without diodes anyway). As you say, damage is very unlikely and if the Klipsch factory has dispensed with the diodes on the late AA types then I can too….Yes I can😎