Natural Sound
- Thread starter PeterA
- Start date
I guess that’s what happens when you don’t use a product correctly …As far as I was able to follow it this ML3 has a long career as a "dust collector's special" ...
As far as I was able to follow it this ML3 has a long career as a "dust collector's special" ...
As far as I was able to follow it, this ML3 was never used with appropriate speakers. It is a great design, but as Brad wrote, it has to be used properly.
Yes, Peter, any Lamm equipment having less than three boxes can not be superb ...
Utterly false! These types of comments followed by silly emojis have become quite tiresome.
Thank you Amir. I am really enjoying the improvement. I have a pretty good handle on the differences now between the LP2.1 and LP1 Signature. I will share my thoughts over the weekend.
Dear Peter,
Fantastic, Nice to hear you are enjoying the improvement.
One of the best experience to me is buying New audio equipments and opening the box of audio jewelery.
When for the first time I saw your audio system in this forum I really enjoyed it.
goodluck
Peter are you going to post your listening impressions of the new system configuration?
I don't want to post here until you have shared your thoughts, even though I've been --yet again-- the beneficiary of your generosity in sharing your system as you bring it ever forward into listening nirvana.
I don't want to post here until you have shared your thoughts, even though I've been --yet again-- the beneficiary of your generosity in sharing your system as you bring it ever forward into listening nirvana.
Salectric, I do not have many mono records. One plan for the future is to buy a third arm with a mono SPU. Perhaps after sailing season.
Hello David,
Yes, I am finishing putting my thoughts to paper. I will post a link to an essay of my listening impressions later today. I am always happy to share the system with friends, and you have indeed been one of the frequent visitors. I look forward to reading your impressions.
Lamm Industries LP1 Signature phonostage
The Context: How and Why
A couple of months ago I sent one of my ML2s to the Lamm factory to be diagnosed and repaired. One of the tubes went bad and replacing it did not solve the problem. I was in pretty close contact with Elina Lamm, widow of Vladimir during this time, so I asked her if she was ready to start producing new product, specifically, an LP1 Signature phonostage.
I had heard the LP1 twice at David Karmeli’s house in Utah. I had not directly compared it to the LP2.1 Deluxe which I subsequently bought, but I spoke to several owners who had done the comparison, and they described to me what they heard in their own systems. I had been looking for one on the used market for quite a while, but they are difficult to find. It looked like I would have to buy a new one. Elina Lamm told me that she could make one for me. I told her that I wanted the sale to go through David and he then arranged the details.
It took about two weeks to assemble, break-in and test the three units. Lamm then measured it for compliance to specifications, and crated it for shipping. Lamm requires all shipments to be via air freight. I received three new wooden crates from FedEx two days later.
Lamm recommends three or four additional days of break-in. Adding the extra two boxes for the mono power supplies requires me to add another small rack to my equipment area. I now have seven boxes for the phono and preamp. I have designed a new smaller rack and will build it in the next few weeks. In the meantime, I am using a temporary plywood platform on dolly feet with two 140 lb steel plates, one for each power supply.
The set up is very straightforward. The LP1 control unit replaces the LP2.1 on the main rack’s top shelf, next to the turntable. It is connected to each power supply by an umbilical cord. Each power supply is plugged into a Hubbell industrial duplex outlet on a dedicated circuit to a dedicated audio-only electrical panel. The two LL1 power supplies are also plugged into their own Hubbell duplex on a separate circuit to the same panel. All four power cords are ddk’s Ching Cheng cords. All Lamm gear is powered on 24/7.
A few weeks after I had decided to buy the Micro Seiki SX8000II turntable and returned from my first visit to DDK in Utah, I received two large pallets with the new turntable and two phono stages, the Lamm LP2.1 Deluxe and the van den Hul Holy Grail. Based on what I had heard at David’s house, I wanted to compare these to my Pass XP27 phono stage. I preferred the LP2.1 to both the Pass and the vdH, and thus began my switch to full Lamm electronics and eventually to my new LP1 Signature phono stage.
To be continued...
The Context: How and Why
A couple of months ago I sent one of my ML2s to the Lamm factory to be diagnosed and repaired. One of the tubes went bad and replacing it did not solve the problem. I was in pretty close contact with Elina Lamm, widow of Vladimir during this time, so I asked her if she was ready to start producing new product, specifically, an LP1 Signature phonostage.
I had heard the LP1 twice at David Karmeli’s house in Utah. I had not directly compared it to the LP2.1 Deluxe which I subsequently bought, but I spoke to several owners who had done the comparison, and they described to me what they heard in their own systems. I had been looking for one on the used market for quite a while, but they are difficult to find. It looked like I would have to buy a new one. Elina Lamm told me that she could make one for me. I told her that I wanted the sale to go through David and he then arranged the details.
It took about two weeks to assemble, break-in and test the three units. Lamm then measured it for compliance to specifications, and crated it for shipping. Lamm requires all shipments to be via air freight. I received three new wooden crates from FedEx two days later.
Lamm recommends three or four additional days of break-in. Adding the extra two boxes for the mono power supplies requires me to add another small rack to my equipment area. I now have seven boxes for the phono and preamp. I have designed a new smaller rack and will build it in the next few weeks. In the meantime, I am using a temporary plywood platform on dolly feet with two 140 lb steel plates, one for each power supply.
The set up is very straightforward. The LP1 control unit replaces the LP2.1 on the main rack’s top shelf, next to the turntable. It is connected to each power supply by an umbilical cord. Each power supply is plugged into a Hubbell industrial duplex outlet on a dedicated circuit to a dedicated audio-only electrical panel. The two LL1 power supplies are also plugged into their own Hubbell duplex on a separate circuit to the same panel. All four power cords are ddk’s Ching Cheng cords. All Lamm gear is powered on 24/7.
A few weeks after I had decided to buy the Micro Seiki SX8000II turntable and returned from my first visit to DDK in Utah, I received two large pallets with the new turntable and two phono stages, the Lamm LP2.1 Deluxe and the van den Hul Holy Grail. Based on what I had heard at David’s house, I wanted to compare these to my Pass XP27 phono stage. I preferred the LP2.1 to both the Pass and the vdH, and thus began my switch to full Lamm electronics and eventually to my new LP1 Signature phono stage.
To be continued...
Last edited:
Continued...
The Sound: What I hear
After installing the LP1 and hooking up the two sets of phono cables, I let it warm up for an hour or two and then did some initial listening. Unlike my previous phono stage comparisons where each unit sounded remarkably different with specific attributes and characters, this sound was very familiar. It did not deviate from what I have come to expect from Lamm: namely, natural sound. However, the delta between the LP1 and LP2.1 startled me. The improvement was immediate and obvious. I have listened for five days and now have a pretty good understanding of how the two phono stages sound different.
The first impression is simply of “more”. Aspects of the sound are not emphasized or enhanced, but every aspect of the sound has improved, more or less evenly. The listening experience has become more like what I hear with live music. It is a big shift. Everything remains in balance, but instruments and voices, and the context in which the music is being made, simply sounds more real. There is greater dynamics, both micro and macro, but also an increase in dynamic range. The noise must be lower because I hear more nuance and more ambiance. There is more of a sense of flow and it is easier to follow musical lines. There is more energy, yet listening seems more relaxed. I am not as interested in details per se, the kinds that draw attention to themselves and perhaps distract from the music, but I do appreciate hearing more of what is on the recording. The LP1 seems to allow more of what is extracted by the cartridge to pass through to the preamp. Basically, the LP1 allows more of what it receives to pass on unrestricted. It allows the listener to hear more life and energy and whatever else is captured in those grooves. It opens the spigot and allows the music to pour forth.
Here are some specific examples of what I hear when playing some of my favorite LPs:
Musica Nuda, Fone, 106/1Lp. Ferruccio Spinetti’s double bass has more raw energy, more gravitas from the opening bows on “Eleanor Rigby” to that final plucked note in “Guarda Che Luna”. The transient is more precise, instant and convincing, the sustain has more weight and body, and the decay hangs in the air longer. The launch is more pronounced and the fade has more overlap with what comes next. Petra Magoni’s voice is both more aggressive and subtle, more articulate and nuanced. Together, they draw you more in with their presence and enhanced expressiveness and musical interactions. These two play with and off of each other, and this interplay is now more easily appreciated.
Art Pepper + Eliven, Contemporary Stereo S7568: I just love this music as it reminds me of big bands to which I danced years ago at dances in NYC. It was some of my first exposure to loud live music at close range. The energy, the loudness, the different horn tones, the rhythm, it is all here. The horns have more blat. This LP used to fill the front wall of my listening room. It now fills the whole room. Horn solos were isolated, the musician seemingly separated from the rest of the band, alone in his bubble to make a mark. With the LP1, that musician is now with the band, in their space, a part of it, but now doing his own thing while the bandmates stand and wait to reenter. It is a strange thing, but there is a distinct sense that the players are all there in the room now, just taking turns, when before those not playing disappeared for a while. The clarinet in “Anthropology” now reminds me more of the instrument with which I struggled in middle school, but I will never forget that tone, and I hear it more convincingly now. Finally, the bass line in “Walkin”, always nice, is now easier to follow with greater presence and nuance.
Ella Fitzgerald and Joe Pass, Take Love Easy, Pablo 2310 702: I always loved the song “Lush Life” first heard on CD sung by Clifford Jordan on “Live at Ethell’s, Mapleshade. In fact, I never heard a different version of this song until visiting DDK in Utah and hearing Ella Fitzerald sing it next to Joe Pass in his listening room. Ella sang RIGHT NEXT TO Joe Pass for me and @tima. I had to buy that record. With the LP2.1, it was very good. The LP1 takes it further, putting me right back in front of Ella and Joe. It is the nuance in her voice and his playing, and the sheer presence that bring them to life in my living room. It is a slightly different presentation that it was in Utah, but they are right there in front of me now too. The beauty of that voice captured and played back for me. This is why we have such systems.
Virtuoso Clarinet, BIS LP-62 Stereo: I struggled with the clarinet as a child. My mother played her piano in our living room while we sang Christmas charols. The sound of these two instruments is burned into my memory. Rodion Sjtjedrin, Basso Ostinato is a wonderful piano/clarity piece, side two, track one. It is full of energy and drama. The weight of the Bosendorfer and reedy/wooden tone of the clarinet are more convincing now. Vladimir Lamm spoke about the left and right hands of the pianist and how they should sound distinct and separate. One should “hear” the different hands. I understand now why he mentioned this to DDK. The clarinet sound and beauty here and on the Stravinski piece is now more palpable and meaningful to me, and they take me right back to my childhood and the memories of those sounds and times.
Vivaldi, Les Concertos pour Mandolines, Erato STU 70545: This is interesting music because it combines the intimate, small scale of the two mandolin players on stage right there on the stage with a small chamber orchestra of about eleven players. The shift in scale from intimate to semi-grand and the distinction between the two groups is now more pronounced. The two mandolins are more clear, their back and forth duet, more playful and engaging. They are more grounded on the stage playing side by side. There is more emotion in their playing, the plucks are more immediate and clean. The decays reverberate longer in a more defined space. The massed strings have more power and a more colorful tone. They are no longer simply in the background. The shift in depth between the two solo mandolins and the orchestra is more evident. The presentation is less flat, the performance more convincing.
Sonny Rollins, Way Out West, OJC-337 (S-7530): There is a lot that can be described here, but I want to give a specific example not covered elsewhere: Shelly Manne’s drum playing. The drums always seemed kind of subdued or recessed to me. The sound improved following various changes to the set up of my former system, then even more with my current system. The drums were gradually moved forward with more energy and dynamics. Nuance with brush work became more apparent. With the LP1, the drums have real attack, weight and pressure. The brush is cleaner, more articulate, and the skin on the drums is now a part of the character of the music. There is more detail but also the way it is presented is more as if the Manne is now a part of the trio, not just to keep the rhythm any more. The same for Ray Brown’s bass. The LP1 brings more information and presents it more realistically that did the LP2.1.
To be continued...
The Sound: What I hear
After installing the LP1 and hooking up the two sets of phono cables, I let it warm up for an hour or two and then did some initial listening. Unlike my previous phono stage comparisons where each unit sounded remarkably different with specific attributes and characters, this sound was very familiar. It did not deviate from what I have come to expect from Lamm: namely, natural sound. However, the delta between the LP1 and LP2.1 startled me. The improvement was immediate and obvious. I have listened for five days and now have a pretty good understanding of how the two phono stages sound different.
The first impression is simply of “more”. Aspects of the sound are not emphasized or enhanced, but every aspect of the sound has improved, more or less evenly. The listening experience has become more like what I hear with live music. It is a big shift. Everything remains in balance, but instruments and voices, and the context in which the music is being made, simply sounds more real. There is greater dynamics, both micro and macro, but also an increase in dynamic range. The noise must be lower because I hear more nuance and more ambiance. There is more of a sense of flow and it is easier to follow musical lines. There is more energy, yet listening seems more relaxed. I am not as interested in details per se, the kinds that draw attention to themselves and perhaps distract from the music, but I do appreciate hearing more of what is on the recording. The LP1 seems to allow more of what is extracted by the cartridge to pass through to the preamp. Basically, the LP1 allows more of what it receives to pass on unrestricted. It allows the listener to hear more life and energy and whatever else is captured in those grooves. It opens the spigot and allows the music to pour forth.
Here are some specific examples of what I hear when playing some of my favorite LPs:
Musica Nuda, Fone, 106/1Lp. Ferruccio Spinetti’s double bass has more raw energy, more gravitas from the opening bows on “Eleanor Rigby” to that final plucked note in “Guarda Che Luna”. The transient is more precise, instant and convincing, the sustain has more weight and body, and the decay hangs in the air longer. The launch is more pronounced and the fade has more overlap with what comes next. Petra Magoni’s voice is both more aggressive and subtle, more articulate and nuanced. Together, they draw you more in with their presence and enhanced expressiveness and musical interactions. These two play with and off of each other, and this interplay is now more easily appreciated.
Art Pepper + Eliven, Contemporary Stereo S7568: I just love this music as it reminds me of big bands to which I danced years ago at dances in NYC. It was some of my first exposure to loud live music at close range. The energy, the loudness, the different horn tones, the rhythm, it is all here. The horns have more blat. This LP used to fill the front wall of my listening room. It now fills the whole room. Horn solos were isolated, the musician seemingly separated from the rest of the band, alone in his bubble to make a mark. With the LP1, that musician is now with the band, in their space, a part of it, but now doing his own thing while the bandmates stand and wait to reenter. It is a strange thing, but there is a distinct sense that the players are all there in the room now, just taking turns, when before those not playing disappeared for a while. The clarinet in “Anthropology” now reminds me more of the instrument with which I struggled in middle school, but I will never forget that tone, and I hear it more convincingly now. Finally, the bass line in “Walkin”, always nice, is now easier to follow with greater presence and nuance.
Ella Fitzgerald and Joe Pass, Take Love Easy, Pablo 2310 702: I always loved the song “Lush Life” first heard on CD sung by Clifford Jordan on “Live at Ethell’s, Mapleshade. In fact, I never heard a different version of this song until visiting DDK in Utah and hearing Ella Fitzerald sing it next to Joe Pass in his listening room. Ella sang RIGHT NEXT TO Joe Pass for me and @tima. I had to buy that record. With the LP2.1, it was very good. The LP1 takes it further, putting me right back in front of Ella and Joe. It is the nuance in her voice and his playing, and the sheer presence that bring them to life in my living room. It is a slightly different presentation that it was in Utah, but they are right there in front of me now too. The beauty of that voice captured and played back for me. This is why we have such systems.
Virtuoso Clarinet, BIS LP-62 Stereo: I struggled with the clarinet as a child. My mother played her piano in our living room while we sang Christmas charols. The sound of these two instruments is burned into my memory. Rodion Sjtjedrin, Basso Ostinato is a wonderful piano/clarity piece, side two, track one. It is full of energy and drama. The weight of the Bosendorfer and reedy/wooden tone of the clarinet are more convincing now. Vladimir Lamm spoke about the left and right hands of the pianist and how they should sound distinct and separate. One should “hear” the different hands. I understand now why he mentioned this to DDK. The clarinet sound and beauty here and on the Stravinski piece is now more palpable and meaningful to me, and they take me right back to my childhood and the memories of those sounds and times.
Vivaldi, Les Concertos pour Mandolines, Erato STU 70545: This is interesting music because it combines the intimate, small scale of the two mandolin players on stage right there on the stage with a small chamber orchestra of about eleven players. The shift in scale from intimate to semi-grand and the distinction between the two groups is now more pronounced. The two mandolins are more clear, their back and forth duet, more playful and engaging. They are more grounded on the stage playing side by side. There is more emotion in their playing, the plucks are more immediate and clean. The decays reverberate longer in a more defined space. The massed strings have more power and a more colorful tone. They are no longer simply in the background. The shift in depth between the two solo mandolins and the orchestra is more evident. The presentation is less flat, the performance more convincing.
Sonny Rollins, Way Out West, OJC-337 (S-7530): There is a lot that can be described here, but I want to give a specific example not covered elsewhere: Shelly Manne’s drum playing. The drums always seemed kind of subdued or recessed to me. The sound improved following various changes to the set up of my former system, then even more with my current system. The drums were gradually moved forward with more energy and dynamics. Nuance with brush work became more apparent. With the LP1, the drums have real attack, weight and pressure. The brush is cleaner, more articulate, and the skin on the drums is now a part of the character of the music. There is more detail but also the way it is presented is more as if the Manne is now a part of the trio, not just to keep the rhythm any more. The same for Ray Brown’s bass. The LP1 brings more information and presents it more realistically that did the LP2.1.
To be continued...
Continued...
The King Singers, A French Collection, EMI CSD 3740: Myles Astor introduced me to this recording when I visited him in NYC a few years ago. I told him I liked choral music and he pulled this from his impressive collection and told me that this was one of the best vocal performances, both musically and recording quality, that he knew. I have been enjoying it ever since, but the LP1 brings the singers to life. They are more distinct in space as singers with individual voices, apart on the stage, and yet when they sing together, they fill the room better. The individual timbres are more distinct. There is better inflection and nuance. They are more present. Their voices are projected more into the room and the presentation is more dimensional. There is also more overlap with the sounds as they fills the space. They are individuals singing taking turns than together as a group. The improvement is fairly subtle, but significant in terms of imagining people in front of you and in terms of thinking less about the sound, and more about the music.
Holst, The Planets, Mehta, London, CS6734: I liked this recording mostly for the sound, shifts in scale, all the different instruments in the orchestra, and the sheer magnificence of it all, the grandeur and the delicacy. As with the other recordings, I hear more information now, and it is presented in a more natural way. The orchestra has a presence it did not have before, in a hall that is more real. There is more atmosphere and I am reminded of the clarity I hear live at the BSO. The contrast between the strings, the brass, the percussion. The complexity presented clearly with convincing and beautiful timbre. And like with the other recordings, I now think less about the sound on the recording and more about the music once performed in Los Angeles.
Conclusion: Crossing the Rubicon
It is hard to describe the differences between the LP2.1 Deluxe and the new LP1 Signature in sonic terms beyond the snippets I have written above. If I were to use one word to describe the sound, it is “regal”. The sound is more open and big. Timbre is more accurate. Horns have more blat, strings have more texture, drum skins are more taught, bass strings are looser, cello bodies are more woody. There is greater scale, not in image size but in the more realistic portrayal of the sound in the space where it was recorded. There is more of a physical presence to the sound, what DDK describes as “mass”. These are the things I hear and how I describe them.
More interesting, and important to me now, is how the listening experience has changed. I am paying more attention to the music. It draws me in more. I am more in the here and now of the moment and where the moment might take me. It may sound corny, but I have an easier time imagining the intent of the composer and the interpretation of the player, the message as they say. This new LP1 has me crossing the Rubicon. The river separating sound from music is not as wide anymore, and it has become easier to cross. I am just thrilled.
The King Singers, A French Collection, EMI CSD 3740: Myles Astor introduced me to this recording when I visited him in NYC a few years ago. I told him I liked choral music and he pulled this from his impressive collection and told me that this was one of the best vocal performances, both musically and recording quality, that he knew. I have been enjoying it ever since, but the LP1 brings the singers to life. They are more distinct in space as singers with individual voices, apart on the stage, and yet when they sing together, they fill the room better. The individual timbres are more distinct. There is better inflection and nuance. They are more present. Their voices are projected more into the room and the presentation is more dimensional. There is also more overlap with the sounds as they fills the space. They are individuals singing taking turns than together as a group. The improvement is fairly subtle, but significant in terms of imagining people in front of you and in terms of thinking less about the sound, and more about the music.
Holst, The Planets, Mehta, London, CS6734: I liked this recording mostly for the sound, shifts in scale, all the different instruments in the orchestra, and the sheer magnificence of it all, the grandeur and the delicacy. As with the other recordings, I hear more information now, and it is presented in a more natural way. The orchestra has a presence it did not have before, in a hall that is more real. There is more atmosphere and I am reminded of the clarity I hear live at the BSO. The contrast between the strings, the brass, the percussion. The complexity presented clearly with convincing and beautiful timbre. And like with the other recordings, I now think less about the sound on the recording and more about the music once performed in Los Angeles.
Conclusion: Crossing the Rubicon
It is hard to describe the differences between the LP2.1 Deluxe and the new LP1 Signature in sonic terms beyond the snippets I have written above. If I were to use one word to describe the sound, it is “regal”. The sound is more open and big. Timbre is more accurate. Horns have more blat, strings have more texture, drum skins are more taught, bass strings are looser, cello bodies are more woody. There is greater scale, not in image size but in the more realistic portrayal of the sound in the space where it was recorded. There is more of a physical presence to the sound, what DDK describes as “mass”. These are the things I hear and how I describe them.
More interesting, and important to me now, is how the listening experience has changed. I am paying more attention to the music. It draws me in more. I am more in the here and now of the moment and where the moment might take me. It may sound corny, but I have an easier time imagining the intent of the composer and the interpretation of the player, the message as they say. This new LP1 has me crossing the Rubicon. The river separating sound from music is not as wide anymore, and it has become easier to cross. I am just thrilled.
Yes! I have noticed that happening to Glenn Gould Bach Goldberg Variations more and more as time has gone on, and the system here has continued to evolve. The weight across the entire keyboard is very very different, and as you start to practice and study piano, you begin to hear the pounding elements of how the hammer is making the note...and so the 'weight' of the notes becomes something as you say that is burned into your memory a bit. It feels right when you hear it.
Peter is telling it as he hears it; he is telling it like it is. Last year I had a similar experience as Peter describes when the LP1 Sig replaced the LP2.1 in my own system where it had been in-house for review. My very first impression was: 'ahh, more better Lamm goodness". If any designer bridges the gulf between love of music and audiophilia it is Vladimir Lamm.
Again, congratulations Peter! Great read and I am glad your are getting such fantastic results.
I am just curious about the 24/7. I always thought that keeping tube gear on was just too hard on the tubes. Does switching them off and back on the next day degrade the sound that much? How long does it take to come on song?
Good questions. I'm not Peter but I have long time tube experience. There are periods of time when my tub electronics are turned on 24/7 -- sometimes that is 3-4 days, it can also be 3-4 weeks. Your electricity bill will go up.
The more difficult time for a tube is when it is changing state -- when it goes from cold to fully operational and vice versa. Warm up time depends on the tube and circuit. Lamm recommends a minimum 45 minute warm-up. If cold, I will give the system 90 minutes warm-up before critical listening.
Imo, keeping tube gear on is not hard on the tubes. It is how they are meant to be used. Many tubes can last for years at their operating temperatures. However performance will drop over time for certain tubes. In the ML2/2.2 amps Peter and I use there is a pair of tubes (6NCP output driver) in each monoblock that Lamm suggests changing out once every year or two years, depending on whose documentation you read. The large more expensive 6C33C tubes will last 2-3 years of constant operation assuming plate voltages are properly maintained; best to keep those a bit under maximum. The large GM-70 tubes in the ML3 amps have a recommended 1-1½ year change out period.
Nonetheless heat is the enemy of any electronic gear. It is important to keep tubes clean. Handling them with your bare hands can transfer skin oils and dirt onto the glass. If the glass gets dirty, heat dissipation goes down and internal temperature goes up. Wipe them off with a cloth lightly dampened in alcohol and hold them with a cloth when inserting or removing. Wait for a fully dry surface before turn-on.
Decent ventilation in-rack is very important. Lamm front-end components are ~5½ inches tall. I suggest at least that much room above the component in a rack. On my SRA Scuttle racks there is ~10 inches above the component to the bottom of the shelf above. Optimally racks/shelves should be open front and back. It is not unheard for people to use small fans in tight racks when not listening. I will not put amplifiers in racks.
Given the variable availability of present day manufactury I suggest having two complete replacement tube sets for each component. Perhaps expensive but worthwhile peace of mind and you'll be thankful when/if a tube is no longer available. Russia cut off tube export when the Ukrainian conflict began. Among others, the popular Svetlana 6550C used in ARC power supplies and other gear remains out-of-stock at most US tube dealers.
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