KLH Model Nine’s Incoming

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JonFo

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I’m not sure the CJ is the best amp for these speakers. It seems to run out of steam when I try to turn it up loud. I need to experiment with some other amps to figure out what will work the best. These speakers max out at 100 wpc @ 16 ohms (equivalent to 200 wpc @ 8 ohms), so I can’t drive them with too much power. I’m afraid to hook up my Sanders 800 wpc monoblocs for fear of frying the speakers. But I do think the would benefit from a more powerful amp than my CJ.
Go ahead and give the Sanders a try, I don't think they can damage the units unless you really crank it.

ESLs are voltage driven, and the Sanders monoblocks can put out around 70v (or more, can't remember the spec, the stereo ESL Amp can deliver up to 64v per channel).

If the Model 9 is truly limited to a given power input, then I'd hope David has added a requisite fuse in the circuit to protect the drivers.
However, most drivers get fried by too little power, and amps going into distortion with damaging harmonic content.
 

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This photo shows the back of the power supply before I attached it to the speaker. All the electronics are potted in wax.

Congratulations on getting them set up and running!

Interesting approach to solving two problems: corrosion resistance (no air or moisture access) for XO elements, and nice side-effect of IP protection (can't see the stuff) 😉
 

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Go ahead and give the Sanders a try, I don't think they can damage the units unless you really crank it.

ESLs are voltage driven, and the Sanders monoblocks can put out around 70v (or more, can't remember the spec, the stereo ESL Amp can deliver up to 64v per channel).

If the Model 9 is truly limited to a given power input, then I'd hope David has added a requisite fuse in the circuit to protect the drivers.
However, most drivers get fried by too little power, and amps going into distortion with damaging harmonic content.
Yeah, David said I don’t need to give them more than about 40 volts. Above that, the woofer panels can arc and put pinholes in the film. I think I may try the Sanders anyway and just be very careful with the volume knob. Ultimately, I think these won’t play as loud as the Summits due to not having a cone woofer for the bass.
 

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Yeah, David said I don’t need to give them more than about 40 volts. Above that, the woofer panels can arc and put pinholes in the film. I think I may try the Sanders anyway and just be very careful with the volume knob.
Ah, glad he shared a specific limit.

This is why I love my DriveRack; I'd just whip out Excel and calculate the input voltage to the amp necessary to have output reach 40v, and then set a limiter on the outputs of the DBX to clamp the signal, so it never exceeds that. The DBX limiters are highly configurable soft limiters with few audible side effects (plus, one hopes the overall system is designed so they are only worst-case scenario protections.

An example is the feed to my Infinite Baffle sub, which can be driven to over-excursion with very low wattage, so limiters are a necessity there. Thankfully, I had them configured, and when I had an oopsie with a connection from the pre-amp while the rest was powered on, my IB drivers (and the Monolith Woofers) were saved by the limiters.

Not that it helps you in the least right now, but worth a thought as folks move further into active systems.

If you deploy a DEQX processor, you could integrate some mid-bass modules and subs with the Model 9 and address the expected gap in those regions. Plus, you can apply limiters to the mains out. That and the speaker EQ plus room correction might put the Model 9 in a whole new league.
Adding the MBM to my rig allowed me to lower the overall volume level by 3 or 4dB, so the ESL is running at a lower level now.
 

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Oh man , what a lucky guy. Now I want a pair! Just kidding, my wife would kill me. Enjoy your listening.
 

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If you deploy a DEQX processor, you could integrate some mid-bass modules and subs with the Model 9 and address the expected gap in those regions. Plus, you can apply limiters to the mains out. That and the speaker EQ plus room correction might put the Model 9 in a whole new league.
Adding the MBM to my rig allowed me to lower the overall volume level by 3 or 4dB, so the ESL is running at a lower level now.
That would be an ideal way to set up these speakers. But alas, not in the cards for me. I’ll put these in my den in the new house, where I’ll never need to play them too loudly. Besides, I’ve got my Summits for when I want to really crank it up. And they’ll be in a soundproof acoustically-treated room.
 

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Been awhile since I posted and I wanted to update you guys on my journey with these vintage speakers. The sound of the refurbished pair of Model Nines is sublime. Imaging and detail in spades. Better even than any ML I’ve listened to (and I’ve heard a lot of Martin Logan’s!). Being a full range electrostatic that puts out down to 40 Hz., they still can’t match the Summits in the low bass. Those Summit woofers provide a solid bottom end that I’ve found is absolutely necessary for my musical enjoyment. So I’ve paired them with my Descent subwoofer, which is good enough for now. I have plans for the future, though, and I’ll get into that later. But first, a story..,

Things were going so well with the Sanders Sound 800 wpc monoblocs. Even though the Model Nines are rated for closer to 100 wpc. I was very careful not to turn the volume up and send too much voltage to the speakers. They can handle about 35 volts max, and the Sanders amps can double that. I was going directly from my PS Audio Direct Stream DAC into the amps and the sound was perfect. But hey, I’m an audiophool. Can’t be satisfied with good enough. Right? So I started wondering whether the sound might improve if I connected my ARC Ref 3 preamp into the mix. It’s always sounded great with the Sanders amps. Great idea! Right? Right? Wrong.

I haven’t used the Ref 3 in a few years. It’s been sitting gathering dust. I hooked it all up, turned on the preamp and let it warm up for a minute (not long enough, obviously), and turned on the amps. The preamp was still on mute, so I was covered. Right? Wrong again. The power tube of the preamp started arcing, like little lightning bolts going off inside the tube. And a loud crackle came across the speakers (even though the preamp was muted!). I didn’t have time to react before the speakers shut down. Silent. They never put out another sound. I checked the amp with another speaker and it was working fine. Checked the speakers with another amp and nada. Nothing.

So I worked with David to troubleshoot. I checked the fuses. The main fuse is slow blow and opaque, so you can’t tell if it’s blown. I checked it with a multimeter and was showing some low ohms, so I didn’t think it was blown. It should have read out of range, but it didn’t. So I sent the power supplies back to David, thinking I had blown the transformers. But, nope. Blown fuse. He replaced the fuses and sent them back. Most expensive fuses I have ever purchased and I wasn’t even mad. Still beats the cost of replacing vintage transformers. By a long shot!

Put it all back together and it sounds just as wonderful as ever. Whew! So, no ARC Ref 3 for these speakers. And I’ve moved the too powerful Sanders amps out and replaced them with my Pass Labs X350.5. It’s still more power than they can handle, but by being careful with the volume control and not having any tubes in the chain to go bad, I think I’m pretty safe. I have to say, the Pass sounds even better. The Sanders are more neutral. The Pass, outputting the first 25 watts or so at Class A bias, is a bit warmer. But it sounds heavenly with these speakers. I’m quite content for now. I’ll try to get a photo to post with the Pass Labs amp next time I have a listening session.

But I’m still thinking that the low end could be better. The single Descent is a bit limiting. It doesn’t have a lot of adjustability, and I’m a firm believer in multiple subs for evening out the bass response. So I’ve decided that I’m going to purchase a pair of PSA 15” subs to pair with these speakers in the next house. I’m also seriously considering getting an antimode 2.0 dual core for room correction of the bass and to help me integrate the new subs with the speakers. Not sure when I’m going to make the purchase, but that is my current plan. Love to hear any thoughts or suggestions on that. I’ll try to get a new pic posted in the next few days. For now, I’m just enjoying the music on these speakers that are older than me. And at some point I guess I’ll have to contact Audio Research to source a new power tube for the Ref 3. Can’t wait to get this system and these speakers into the den of my new house. They sound incredible and are such a great conversation piece for all those folks that haven’t a clue about electrostatic speakers.
 

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Been awhile since I posted and I wanted to update you guys on my journey with these vintage speakers. The sound of the refurbished pair of Model Nines is sublime. Imaging and detail in spades. Better even than any ML I’ve listened to (and I’ve heard a lot of Martin Logan’s!). Being a full range electrostatic that puts out down to 40 Hz., they still can’t match the Summits in the low bass. Those Summit woofers provide a solid bottom end that I’ve found is absolutely necessary for my musical enjoyment. So I’ve paired them with my Descent subwoofer, which is good enough for now. I have plans for the future, though, and I’ll get into that later. But first, a story..,

Things were going so well with the Sanders Sound 800 wpc monoblocs. Even though the Model Nines are rated for closer to 100 wpc. I was very careful not to turn the volume up and send too much voltage to the speakers. They can handle about 35 volts max, and the Sanders amps can double that. I was going directly from my PS Audio Direct Stream DAC into the amps and the sound was perfect. But hey, I’m an audiophool. Can’t be satisfied with good enough. Right? So I started wondering whether the sound might improve if I connected my ARC Ref 3 preamp into the mix. It’s always sounded great with the Sanders amps. Great idea! Right? Right? Wrong.

I haven’t used the Ref 3 in a few years. It’s been sitting gathering dust. I hooked it all up, turned on the preamp and let it warm up for a minute (not long enough, obviously), and turned on the amps. The preamp was still on mute, so I was covered. Right? Wrong again. The power tube of the preamp started arcing, like little lightning bolts going off inside the tube. And a loud crackle came across the speakers (even though the preamp was muted!). I didn’t have time to react before the speakers shut down. Silent. They never put out another sound. I checked the amp with another speaker and it was working fine. Checked the speakers with another amp and nada. Nothing.

So I worked with David to troubleshoot. I checked the fuses. The main fuse is slow blow and opaque, so you can’t tell if it’s blown. I checked it with a multimeter and was showing some low ohms, so I didn’t think it was blown. It should have read out of range, but it didn’t. So I sent the power supplies back to David, thinking I had blown the transformers. But, nope. Blown fuse. He replaced the fuses and sent them back. Most expensive fuses I have ever purchased and I wasn’t even mad. Still beats the cost of replacing vintage transformers. By a long shot!

Put it all back together and it sounds just as wonderful as ever. Whew! So, no ARC Ref 3 for these speakers. And I’ve moved the too powerful Sanders amps out and replaced them with my Pass Labs X350.5. It’s still more power than they can handle, but by being careful with the volume control and not having any tubes in the chain to go bad, I think I’m pretty safe. I have to say, the Pass sounds even better. The Sanders are more neutral. The Pass, outputting the first 25 watts or so at Class A bias, is a bit warmer. But it sounds heavenly with these speakers. I’m quite content for now. I’ll try to get a photo to post with the Pass Labs amp next time I have a listening session.

But I’m still thinking that the low end could be better. The single Descent is a bit limiting. It doesn’t have a lot of adjustability, and I’m a firm believer in multiple subs for evening out the bass response. So I’ve decided that I’m going to purchase a pair of PSA 15” subs to pair with these speakers in the next house. I’m also seriously considering getting an antimode 2.0 dual core for room correction of the bass and to help me integrate the new subs with the speakers. Not sure when I’m going to make the purchase, but that is my current plan. Love to hear any thoughts or suggestions on that. I’ll try to get a new pic posted in the next few days. For now, I’m just enjoying the music on these speakers that are older than me. And at some point I guess I’ll have to contact Audio Research to source a new power tube for the Ref 3. Can’t wait to get this system and these speakers into the den of my new house. They sound incredible and are such a great conversation piece for all those folks that haven’t a clue about electrostatic speakers.
I just looked at the PSA subs and it looks like they only have 12 inch and 18 inch now. I dont see 15 inch listed. Those subs all look nice. Just looked again and it does seem there are some. The drop down menu at top only has 12 and 18 for some reason. Looks like you have to drop down to sealed and ported to get them to show up.
 

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I just looked at the PSA subs and it looks like they only have 12 inch and 18 inch now. I dont see 15 inch listed. Those subs all look nice. Just looked again and it does seem there are some. The drop down menu at top only has 12 and 18 for some reason. Looks like you have to drop down to sealed and ported to get them to show up.
I’m thinking about a pair of these: S1512

Not too large for the den, but capable of a lot of quality bass output. And these PSA woofers are fast. Stop and start on a dime. Perfect match for electrostats.
 

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I’m thinking about a pair of these: S1512

Not too large for the den, but capable of a lot of quality bass output. And these PSA woofers are fast. Stop and start on a dime. Perfect match for electrostats.
Nice! I thought you were more for using ported subs? Maybe since this will be for your den and music only, you figure sealed? When I finally build a new place with a dedicated home theater, I figure on using some of PSA subs. The value of them seems incredible. I bet just one of their twin 18 inch subs would be plenty for a home theater.

Do you think that sub would sound good for music too? I think I will probably do the same as now and use the same room for music and theater.
 

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Nice! I thought you were more for using ported subs? Maybe since this will be for your den and music only, you figure sealed? When I finally build a new place with a dedicated home theater, I figure on using some of PSA subs. The value of them seems incredible. I bet just one of their twin 18 inch subs would be plenty for a home theater.

Do you think that sub would sound good for music too? I think I will probably do the same as now and use the same room for music and theater.
I will be using ported subs in the theater. I think ported subs are absolutely a necessity for home theater applications. They simply have more output in the lower regions so critical for movie effects. But I prefer sealed subs for music-only applications. And sealed just happen to be smaller, which is exactly what I need for the den. But yes, I think the big ported PSA subs will still sound great with music.

Yes, those TV3613’s are amazing and just one of them would definitely blow you away. But more smaller subs are better for evening out room modes and getting better bass across multiple seats. Two separate 18” subs, properly located, would give you better sound overall than a single one of those. For home theater, two subs are always better than one, and four or even more are best to get the smoothest bass response across multiple seats.
 

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Put it all back together and it sounds just as wonderful as ever. Whew!
Wow, what a scare; glad it was just the fuses.

I’m also seriously considering getting an antimode 2.0 dual core for room correction of the bass and to help me integrate the new subs with the speakers. Not sure when I’m going to make the purchase, but that is my current plan. Love to hear any thoughts or suggestions on that.
Anything that allows for time alignment and EQ is a win. A few ms of delta can make a difference. The AntiMode does detect and set delay automatically for the sub.

If using more than one sub, though, now you have a challenge with time alignment depending on where it is located.
 

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I will be using ported subs in the theater. I think ported subs are absolutely a necessity for home theater applications. They simply have more output in the lower regions so critical for movie effects. But I prefer sealed subs for music-only applications. And sealed just happen to be smaller, which is exactly what I need for the den. But yes, I think the big ported PSA subs will still sound great with music.

Yes, those TV3613’s are amazing and just one of them would definitely blow you away. But more smaller subs are better for evening out room modes and getting better bass across multiple seats. Two separate 18” subs, properly located, would give you better sound overall than a single one of those. For home theater, two subs are always better than one, and four or even more are best to get the smoothest bass response across multiple seats.
Yeah, I was thinking that too. As long as the room is large enough. I think that's the benefit of having the two driver subs like that which are stacked. Smaller foot print.
 

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Wow, what a scare; glad it was just the fuses.


Anything that allows for time alignment and EQ is a win. A few ms of delta can make a difference. The AntiMode does detect and set delay automatically for the sub.

If using more than one sub, though, now you have a challenge with time alignment depending on where it is located.
How do you coordinate two subs then? If you have them connected through the LFE terminals, won't the preamp or receiver do that for you when running its DSP? My Marantz seems to do that with Audyssey.

Not sure how that antimode works. If a sub uses PBK, you'd run that on each sub independently.
 

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Wow, what a scare; glad it was just the fuses.


Anything that allows for time alignment and EQ is a win. A few ms of delta can make a difference. The AntiMode does detect and set delay automatically for the sub.

If using more than one sub, though, now you have a challenge with time alignment depending on where it is located.
Given that they’ll be in the den, the subs will be placed based on esthetics vs. where they would sound the best (and we all know from experience that those two factors rarely coincide). Which is one reason I want some room correction for the bass. Most probably the subs will be on the front wall, just behind each speaker, (positioned at about 1/3 and 2/3 of the length of the wall) and they should be equidistant from the main listening position.
 

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Given that they’ll be in the den, the subs will be placed based on esthetics vs. where they would sound the best (and we all know from experience that those two factors rarely coincide). Which is one reason I want some room correction for the bass. Most probably the subs will be on the front wall, just behind each speaker, (positioned at about 1/3 and 2/3 of the length of the wall) and they should be equidistant from the main listening position.
Rich,

So glad you're enjoying these fantastic speakers. I would add that if you have the room, they sound even better when multiple pairs are setup, side by side. KLH even made a bracket to connect two pair. The bracket was about a 30 degree angle. I own 7 pair of KLH Nines and have experimented with them in various configurations. When setup and working properly, they are truly remarkable. J. Gordon Holt had them as his only "Class A" speaker for many years. I might also add.. The classic combination used by Saul Marantz and Henry Kloss to power the KLH Nines were the Marantz Nine amplifiers, named for that purpose.

Enjoy!!
 
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Rich,

So glad you're enjoying these fantastic speakers. I would add that if you have the room, they sound even better when multiple pairs are setup, side by side. KLH even made a bracket to connect two pair. The bracket was about a 30 degree angle. I own 7 pair of KLH Nines and have experimented with them in various configurations. When setup and working properly, they are truly remarkable. J. Gordon Holt had them as his only "Class A" speaker for many years. I might also add.. The classic combination used by Saul Marantz and Henry Kloss to power the KLH Nines were the Marantz Nine amplifiers, named for that purpose.

Enjoy!!
Cosmos, thanks for the reply. I am familiar with the bracket and the benefits of putting two pairs together. Unfortunately, I don’t think my wife would allow that in our den. Maybe some day. Can’t believe you own 7 pairs of these! That’s insane! Have you had any of them refurbished by David Janssen? If not, I can highly recommend his refurbishment and upgrade service. He brings them back to better than original condition and is really focused on continuing his father’s legacy and giving new life to these aging, but amazing, speakers.

I know the Marantz and some Macintosh tube amps were the standard for these back then. I found I couldn’t go as loud as I wanted with my Conrad Johnson Premier 140 tube amp before I ran into clipping. No problems with the Pass Labs. I get the volume level I want (low 80’s dB’s average) without clipping or sending too much voltage to the speakers. At the dynamic peaks, I’m seeing voltage peaks of close to 24 volts and David said I don’t want to feed them more than 35 volts. So I think I’m in a safe range, and the amp stays in class A bias and sounds incredible. Thanks so much for your input. Would love to hear more about your journey with the Model Nine’s. How on earth did you end up with seven pairs?
 

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Cosmos, thanks for the reply. I am familiar with the bracket and the benefits of putting two pairs together. Unfortunately, I don’t think my wife would allow that in our den. Maybe some day. Can’t believe you own 7 pairs of these! That’s insane! Have you had any of them refurbished by David Janssen? If not, I can highly recommend his refurbishment and upgrade service. He brings them back to better than original condition and is really focused on continuing his father’s legacy and giving new life to these aging, but amazing, speakers.

I know the Marantz and some Macintosh tube amps were the standard for these back then. I found I couldn’t go as loud as I wanted with my Conrad Johnson Premier 140 tube amp before I ran into clipping. No problems with the Pass Labs. I get the volume level I want (low 80’s dB’s average) without clipping or sending too much voltage to the speakers. At the dynamic peaks, I’m seeing voltage peaks of close to 24 volts and David said I don’t want to feed them more than 35 volts. So I think I’m in a safe range, and the amp stays in class A bias and sounds incredible. Thanks so much for your input. Would love to hear more about your journey with the Model Nine’s. How on earth did you end up with seven pairs?
Yeah, 7 pairs is incredible. I bet they are really hard to find too. Just finding that many must not be easy.
 
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