EdipisReks
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Here is my promised and long overdue PPX3 review/6CG7 tube-rolling guide. First, let me describe the equipment used. My source is a Yamaha DV-S5770 universal disc player with the DAC 192 kHz oversampling feature enabled. It is connected to my Singlepower PPX3 by the RCA cables that came with the dvd player. I am currently awaiting a pair of Magwire interconnects, and while I am generally not a big believer in cables making a difference (I bought these mostly due to their quality construction and non susceptibility to RFI, which is a problem in my apartment), I will update this review if I find the Magwire IC’s do make an audible difference. The amplifier is a point-to-point wired PPX3 with the Solen stage one power supply cap upgrade. The headphones are my Sony CD3000’s. Both the amp and dvd player are powered from an APC UPS/surge protector using standard unshielded power cables. For the sake of simplicity, I am only using one CD, which is King Crimson’s The ConstruKction Of Light (from here on called tCoL). This album was chosen due to the fairly varied nature of the songs, and the density of sound that it presents. In my experience, audio equipment usually shows flaws most clearly when playing complicated, dense, fast music, and tCoL presents this in spades.
For the tube-rolling section, the following tubes and combinations were used: gain RCA Cleartop 6CG7, output 2x RCA Cleartop; gain Ei 6FQ7, output 2x RCA Cleartop; gain Sylvania 6CG7, output 2x RCA Cleartop 6CG7; gain Ei 6FQ7, output 2x Ei 6CG7; gain Sylvania 6CG7, output 2x Sylvania 6CG7; gain Sylvania 6CG, output 2x National Gold Line matched 6CG7; gain RCA Cleartop 6CG7, output 2x GE JAN (joint army navy) 6CG7; gain Sylvania 6CG7, output 2x GE JAN (joint army navy) 6CG7; output Sylvania 6CG7, output 2x Cryo-Vac cryogenically treated 6CG7; gain RCA Cleartop 6CG7, output 2x Cryo-Vac cryogenically treated RCA Cleartop 6CG7; gain Cryo-Vac cryogenically treated 6CG7, output 2x RCA Cleartop 6CG7. I also have 1 Marconi 6CG7, 1 Marconi 6FQ7, and one Electro-Harmonix 6CG7, but I am not totally comfortable reviewing single examples of tubes. I will say this, the Marconi 6CG7 sounds VERY good in the gain position. In cases where I only have 2 examples of a particular tube, I avoid using one as gain. This prevents me from doing long term listening on some good combinations, but I wish to keep the total hours on pairs fairly equal across both tubes. All vacuum tube combinations were given 10 minutes of warm up before listening began. I have found that 10 minutes gives all of the tubes a chance to present most of their sound quality, though they continue to improve until about half an hour of use. If anyone has any particular combination of these tubes they would like me to try, let me know and I will do so.
Since I now have a fairly large selection of vacuum tubes to use, I have made a few very important observations about this amp since I made my initial impressions a couple months back; 1, while the amplifier has certain characteristics that present themselves with all tubes used, the tube selection has a dramatic effect on sound, 2, the output tubes have the most effect on the sound, and 3, the gain tube is an important factor in making up for deficiencies in the output tubes or for reinforcing output tube strengths. Since the vacuum tubes used in this amp have such a dramatic effect on the overall sound quality, I find that I am unable to make a “general” review of the amplifier, as there is no one PPX3 sound. This has been a large factor in why my review has been so long in coming, as I could no simply sit down and write a review of the amplifier. Instead, I have had to become very familiar with all of the tube combinations that I commonly use.
Much like other members of this forum (I’m looking at you, SACD lover) who use tube amps, and Singlepowers in particular, I find myself changing tubes a great deal during longer listening sessions, as I can tweak the sound to be just right for whatever music I’m listening to. To me, this is a major strength of the PPX3, and I’m not “stuck” with any particular sound. I can see why some people would find this to be a liability, as tubes can be quite expensive and it does take some time away from actually listening to the music. I like it.
For the sake of brevity, I will give fairly general impressions of each tube combination.
Gain: RCA Cleartop 6CG7
Output: 2x RCA Cleartop 6CG7
This combination is what I consider to be the “middle of the road” set up. The Cleartops are often described as being very good tubes, and I generally agree with this. I do not think that they are amazing tubes, however. I have 2 distinct types of RCA Cleartops, one that has a sharp prong at the top of the glass tube and exposed, fairly bright filaments, and the other has a rounded extrusion at the top of the tube and filaments that are not as exposed or bright. I cannot tell any difference in sound quality between these tubes, but I tend to match 2 of either type in the output position when I use them, and a single example of the other type in the gain position, as I like how this looks. Onto the sound, I think it is good, but not great. There is nice warmth to the sound, though it is not overly “tubey”. The speed and detail is decent, but there is a tendency of slight congestion in fast, and densely layered sections. For instance, in track six of tCoL, FraKctured, there is fast, dense, layered guitar playing at around the 6 minute mark. With these tubes, the separation between the instruments “vertically” is slightly muddy, and the guitars run together a small amount. It is not unpleasing, but it lacks the clarity that I have heard with other tube combinations and with my previous Meier Audio Corda HA-1 Mk. II, which is a solid-state amplifier. The sound is highly textured, however, and the guitars certainly sound like guitars. The bass is slightly grainy, but is deep and present enough for the musical style. Treble is extended and detailed, and does not seem to have any appreciable roll off. Overall, these are good tubes, and I use them more than any other tubes, both because I have 8 of them and they are expendable, but also because they are very pleasing for non-critical listening, which I do a lot of while on the computer. There is a slight tendency for long term listening fatigue, which I consider to be a symptom of a slightly harsh treble.
Gain: Ei 6FQ7
Output: 2x RCA Cleartop 6CG7
This combination is very similar to the above, but the sound is slightly warmer while at the same time slightly less textured. It is a pleasing combination, but not one that I would go out of my way to use. I do not think that the Ei tube being used as a gain helps out the Cleartops.
Gain: Sylvania 6CG7
Output: 2x RCA Cleartop 6CG7
Ah, now we are talking! The Sylvania tubes are very warm, with a balance that is slightly tilted towards the bass, and this fills in the deficiencies of the Cleartops. The muddiness in layered music disappears, with vertical separation becoming very pleasant and apparent. Bass becomes more upfront, and more textured, and I consider the tonal balance to be very good, with the warmth making most music more enjoyable. I consider this tube combination to be very good, and I suggest that Cleartop users try to find a Sylvania or two for experimentation.
Gain: Ei 6FQ7
Output: 2x Ei 6CG7
This is the tube combination that came with the amp, and I can’t say anything about it other than it’s ok. The sound is slightly warm, slightly slow, slightly muddy, and slightly rolled off at the treble. This, of course, is in comparison to other, better tubes that I have: when I first heard the PPX3 with the Ei tubes, I thought it sounded amazing. These tubes are inexpensive, and very forgiving and non-fatiguing. Those are good qualities in and of themselves.
Gain: Sylvania 6CG7
Output: 2x Sylvania 6CG7
This is a very good combination for some music, but may be too warm and laid back for some. I generally use this combo when listening to woodwind music, but for King Crimson it is too warm for my taste, almost as if the instruments are wrapped in a wooly blanket. This is not to say that it is muddy, or under detailed, because they are clear and as detailed as anything else, the sound is simply too warm for me when it comes to rock and roll. There is no fatigue with these tubes, however, and I have listened to them for upward of 8 hours before.
Gain: Sylvania 6CG7
Output: 2x National Gold Line matched 6CG7
Wow. This combination is simply amazing. If I had more of these tubes, I might never take them out. The sound is super extended in both bass and treble, with a midrange to die for. The sound is highly detailed, yet totally non-fatiguing. The sound is very fast, and separated; in the song FraKctured, Robert Fripp’s guitar has this amazing attack at the beginning of each note, and the decay between the notes starting at around 2:15 is just right. The bass is just perfect, and doesn’t get in the way of the music at all. Songs with big booming bass have big booming bass with this combo, and songs with tight, deep, highly textured bass have tight, deep, highly textured bass. I actually have a hard time describing this combination of tubes, it just sounds so right, so natural. The National Gold Lines do well with other tubes in the gain position, but the Sylvania is definitely the best match, as it brings a touch of controlled warmth to the sound. I love this combo.
Gain: RCA Cleartop 6CG7 or Sylvania 6CG7
Output: 2x GE JAN 6CG7
The GE JAN tubes are bass machines. They are detailed, textured, and extended, but the bass brings a slight unnaturalness to the sound. Having said that, they sound really good. The GE’s are very smooth sounding, yet convey lots of data to the ears. The RCA Cleartop in the gain position seems to give the GE’s a bit more extension than the Sylvania tube, but the Sylvania tube gives a slightly warmer sound and a slightly sweeter midrange that is great for vocals. The Sylvania tube also seems to give a slight treble roll off, but this isn’t apparent in most music. In general, I like the RCA/GE combo for rock, such as King Crimson, and the Sylvania/GE combo for classical music, especially piano. The GE tubes also look very cool. If you can stand a bumped up, slightly unnatural bass, you’ll probably like the GE JAN tubes.
Gain: Sylvania 6CG7 or RCA Cleartop 6CG7
Output: 2x Cryo-Vac cryogenically treated RCA Cleartop 6CG7
I don’t have too much to say about the Cryo Cleartops, as I don’t like them and I can’t bring myself to listen to them for long at all. When SACD Lover gave them to me, he said that they had a weird treble that he didn’t like. I was a bit skeptical, as these can be pretty expensive and a lot of people like them, but the proof is in the pudding. Well, SACD lover was totally correct. There is a quality to the treble that verges on the painful, at least to my ear. If it makes sense, I would call the treble slightly “tizzy”. It’s almost like fingernails on a chalkboard, but it’s not totally audible. I don’t hear scratchiness, per se, but as soon as I put them on I get a weird “high pitched” pressure in my ears, which immediately goes away when I take the phones off. This is unbearable with a RCA Cleartop as the gain tube, but the Sylvania tubes are smooth enough that I can listen to the tubes for a little while. Part of this might be a lack of synergy with the CD3000’s, so I won’t completely make up my mind until I get to pair them with Sennheisers, but I’m not holding my breath. I think it’s a real shame, as I can hear a very good bass and midrange presentation when paired with the Sylvanias, but I can’t stand to listen to them long enough to really tell.
Edit: July 10, 2005
I've been listening to the Cryos in the output position every day for the past couple weeks, and i've found that i've gotten used to the tubes and no longer feel discomfort. I'm going to keep the initial impressions in case anyone else tries the Cryos and feels the same discomfort that I did. Now that I'm used to the tubes, i think they sound really great! They take everything the regular Clear Tops give and racket it up a notch, with crystalline, crisp treble, smooth midrange and great detail. I do think that they require a slightly bassy gain tube, as the Cryo Clear Tops seem to have slightly less present in the bass than the regular Clear Tops, but the Sylvania and GE JAN tubes provide this bass kick with no problems.
added June 21st, 2005
Gain: Cryo-Vac Cryogenically treated RCA Cleartop 6CG7
Output: 2x RCA Cleartop 6CG7
This combination was brought to my attention after i first posted my review. I hadn't tried it as i didn't want to use tubes that i only have 2 examples of as gain, as i want to match the hours they were used as much as possible. This was a mistake, as this combination sounds great! It is right up there with the Sylvana+National Gold Line combo, but strikingly different. Whereas the Sylvania+National combo is smooth and warm, but fast and detailed, the Cryo+Cleartop combo is slightly cold, fast, extended and almost crystaline. It is a great combo, which really brings out detail and shimmers at the top end. It fixes the slight seperation problems that i had with the Cleartops, and they really sing. I think that the Cryos might just be too much when used as output with the CD3k's, and really shine when used as gain. The CD3k's are pretty treble heavy phones, so i think it's probably natural that the Cryos, which have extended, crisp treble, has an adverse effect when paied with the Sonys. I am now very much looking forward to trying the Cryos with slightly more laid back phones like the Sennheiser HD600's or 650's.
July 10, 2005 edit to the June 21st addition: I got used to the Cryos. i'm not sure what caused the discomfort I was feeling, but a couple weeks of acclimation fixed it. I no longer think the Cryos are "too much" when used in combination with the CD3k's, and I now very much like them.
added June 22nd, 2005
Gain: Cryo-Vac Cryogenically treated RCA Cleartop 6CG7
Output: 2x National Gold Line Matched 6CG7
This combination is great. The Nationals give the sound a smooth sweetness, while the Cryo Cleartop in the gain position keeps the extension and crystalline quality that i liked so much in the Cryo+Cleartop combo. I think that for lighter rock, acoustic, chamber music, etc, the Cryo+National combo is a great one, though i miss the "center mass" for Symphonic and harder rock music that the Sylvania+National combo gives.
I hope that this little review was helpful, and if anyone wants more specific details on any tube combo listed, or you would like me to review tube combinations not listed, let me know. Thanks for reading!
For the tube-rolling section, the following tubes and combinations were used: gain RCA Cleartop 6CG7, output 2x RCA Cleartop; gain Ei 6FQ7, output 2x RCA Cleartop; gain Sylvania 6CG7, output 2x RCA Cleartop 6CG7; gain Ei 6FQ7, output 2x Ei 6CG7; gain Sylvania 6CG7, output 2x Sylvania 6CG7; gain Sylvania 6CG, output 2x National Gold Line matched 6CG7; gain RCA Cleartop 6CG7, output 2x GE JAN (joint army navy) 6CG7; gain Sylvania 6CG7, output 2x GE JAN (joint army navy) 6CG7; output Sylvania 6CG7, output 2x Cryo-Vac cryogenically treated 6CG7; gain RCA Cleartop 6CG7, output 2x Cryo-Vac cryogenically treated RCA Cleartop 6CG7; gain Cryo-Vac cryogenically treated 6CG7, output 2x RCA Cleartop 6CG7. I also have 1 Marconi 6CG7, 1 Marconi 6FQ7, and one Electro-Harmonix 6CG7, but I am not totally comfortable reviewing single examples of tubes. I will say this, the Marconi 6CG7 sounds VERY good in the gain position. In cases where I only have 2 examples of a particular tube, I avoid using one as gain. This prevents me from doing long term listening on some good combinations, but I wish to keep the total hours on pairs fairly equal across both tubes. All vacuum tube combinations were given 10 minutes of warm up before listening began. I have found that 10 minutes gives all of the tubes a chance to present most of their sound quality, though they continue to improve until about half an hour of use. If anyone has any particular combination of these tubes they would like me to try, let me know and I will do so.
Since I now have a fairly large selection of vacuum tubes to use, I have made a few very important observations about this amp since I made my initial impressions a couple months back; 1, while the amplifier has certain characteristics that present themselves with all tubes used, the tube selection has a dramatic effect on sound, 2, the output tubes have the most effect on the sound, and 3, the gain tube is an important factor in making up for deficiencies in the output tubes or for reinforcing output tube strengths. Since the vacuum tubes used in this amp have such a dramatic effect on the overall sound quality, I find that I am unable to make a “general” review of the amplifier, as there is no one PPX3 sound. This has been a large factor in why my review has been so long in coming, as I could no simply sit down and write a review of the amplifier. Instead, I have had to become very familiar with all of the tube combinations that I commonly use.
Much like other members of this forum (I’m looking at you, SACD lover) who use tube amps, and Singlepowers in particular, I find myself changing tubes a great deal during longer listening sessions, as I can tweak the sound to be just right for whatever music I’m listening to. To me, this is a major strength of the PPX3, and I’m not “stuck” with any particular sound. I can see why some people would find this to be a liability, as tubes can be quite expensive and it does take some time away from actually listening to the music. I like it.
For the sake of brevity, I will give fairly general impressions of each tube combination.
Gain: RCA Cleartop 6CG7
Output: 2x RCA Cleartop 6CG7
This combination is what I consider to be the “middle of the road” set up. The Cleartops are often described as being very good tubes, and I generally agree with this. I do not think that they are amazing tubes, however. I have 2 distinct types of RCA Cleartops, one that has a sharp prong at the top of the glass tube and exposed, fairly bright filaments, and the other has a rounded extrusion at the top of the tube and filaments that are not as exposed or bright. I cannot tell any difference in sound quality between these tubes, but I tend to match 2 of either type in the output position when I use them, and a single example of the other type in the gain position, as I like how this looks. Onto the sound, I think it is good, but not great. There is nice warmth to the sound, though it is not overly “tubey”. The speed and detail is decent, but there is a tendency of slight congestion in fast, and densely layered sections. For instance, in track six of tCoL, FraKctured, there is fast, dense, layered guitar playing at around the 6 minute mark. With these tubes, the separation between the instruments “vertically” is slightly muddy, and the guitars run together a small amount. It is not unpleasing, but it lacks the clarity that I have heard with other tube combinations and with my previous Meier Audio Corda HA-1 Mk. II, which is a solid-state amplifier. The sound is highly textured, however, and the guitars certainly sound like guitars. The bass is slightly grainy, but is deep and present enough for the musical style. Treble is extended and detailed, and does not seem to have any appreciable roll off. Overall, these are good tubes, and I use them more than any other tubes, both because I have 8 of them and they are expendable, but also because they are very pleasing for non-critical listening, which I do a lot of while on the computer. There is a slight tendency for long term listening fatigue, which I consider to be a symptom of a slightly harsh treble.
Gain: Ei 6FQ7
Output: 2x RCA Cleartop 6CG7
This combination is very similar to the above, but the sound is slightly warmer while at the same time slightly less textured. It is a pleasing combination, but not one that I would go out of my way to use. I do not think that the Ei tube being used as a gain helps out the Cleartops.
Gain: Sylvania 6CG7
Output: 2x RCA Cleartop 6CG7
Ah, now we are talking! The Sylvania tubes are very warm, with a balance that is slightly tilted towards the bass, and this fills in the deficiencies of the Cleartops. The muddiness in layered music disappears, with vertical separation becoming very pleasant and apparent. Bass becomes more upfront, and more textured, and I consider the tonal balance to be very good, with the warmth making most music more enjoyable. I consider this tube combination to be very good, and I suggest that Cleartop users try to find a Sylvania or two for experimentation.
Gain: Ei 6FQ7
Output: 2x Ei 6CG7
This is the tube combination that came with the amp, and I can’t say anything about it other than it’s ok. The sound is slightly warm, slightly slow, slightly muddy, and slightly rolled off at the treble. This, of course, is in comparison to other, better tubes that I have: when I first heard the PPX3 with the Ei tubes, I thought it sounded amazing. These tubes are inexpensive, and very forgiving and non-fatiguing. Those are good qualities in and of themselves.
Gain: Sylvania 6CG7
Output: 2x Sylvania 6CG7
This is a very good combination for some music, but may be too warm and laid back for some. I generally use this combo when listening to woodwind music, but for King Crimson it is too warm for my taste, almost as if the instruments are wrapped in a wooly blanket. This is not to say that it is muddy, or under detailed, because they are clear and as detailed as anything else, the sound is simply too warm for me when it comes to rock and roll. There is no fatigue with these tubes, however, and I have listened to them for upward of 8 hours before.
Gain: Sylvania 6CG7
Output: 2x National Gold Line matched 6CG7
Wow. This combination is simply amazing. If I had more of these tubes, I might never take them out. The sound is super extended in both bass and treble, with a midrange to die for. The sound is highly detailed, yet totally non-fatiguing. The sound is very fast, and separated; in the song FraKctured, Robert Fripp’s guitar has this amazing attack at the beginning of each note, and the decay between the notes starting at around 2:15 is just right. The bass is just perfect, and doesn’t get in the way of the music at all. Songs with big booming bass have big booming bass with this combo, and songs with tight, deep, highly textured bass have tight, deep, highly textured bass. I actually have a hard time describing this combination of tubes, it just sounds so right, so natural. The National Gold Lines do well with other tubes in the gain position, but the Sylvania is definitely the best match, as it brings a touch of controlled warmth to the sound. I love this combo.
Gain: RCA Cleartop 6CG7 or Sylvania 6CG7
Output: 2x GE JAN 6CG7
The GE JAN tubes are bass machines. They are detailed, textured, and extended, but the bass brings a slight unnaturalness to the sound. Having said that, they sound really good. The GE’s are very smooth sounding, yet convey lots of data to the ears. The RCA Cleartop in the gain position seems to give the GE’s a bit more extension than the Sylvania tube, but the Sylvania tube gives a slightly warmer sound and a slightly sweeter midrange that is great for vocals. The Sylvania tube also seems to give a slight treble roll off, but this isn’t apparent in most music. In general, I like the RCA/GE combo for rock, such as King Crimson, and the Sylvania/GE combo for classical music, especially piano. The GE tubes also look very cool. If you can stand a bumped up, slightly unnatural bass, you’ll probably like the GE JAN tubes.
Gain: Sylvania 6CG7 or RCA Cleartop 6CG7
Output: 2x Cryo-Vac cryogenically treated RCA Cleartop 6CG7
I don’t have too much to say about the Cryo Cleartops, as I don’t like them and I can’t bring myself to listen to them for long at all. When SACD Lover gave them to me, he said that they had a weird treble that he didn’t like. I was a bit skeptical, as these can be pretty expensive and a lot of people like them, but the proof is in the pudding. Well, SACD lover was totally correct. There is a quality to the treble that verges on the painful, at least to my ear. If it makes sense, I would call the treble slightly “tizzy”. It’s almost like fingernails on a chalkboard, but it’s not totally audible. I don’t hear scratchiness, per se, but as soon as I put them on I get a weird “high pitched” pressure in my ears, which immediately goes away when I take the phones off. This is unbearable with a RCA Cleartop as the gain tube, but the Sylvania tubes are smooth enough that I can listen to the tubes for a little while. Part of this might be a lack of synergy with the CD3000’s, so I won’t completely make up my mind until I get to pair them with Sennheisers, but I’m not holding my breath. I think it’s a real shame, as I can hear a very good bass and midrange presentation when paired with the Sylvanias, but I can’t stand to listen to them long enough to really tell.
Edit: July 10, 2005
I've been listening to the Cryos in the output position every day for the past couple weeks, and i've found that i've gotten used to the tubes and no longer feel discomfort. I'm going to keep the initial impressions in case anyone else tries the Cryos and feels the same discomfort that I did. Now that I'm used to the tubes, i think they sound really great! They take everything the regular Clear Tops give and racket it up a notch, with crystalline, crisp treble, smooth midrange and great detail. I do think that they require a slightly bassy gain tube, as the Cryo Clear Tops seem to have slightly less present in the bass than the regular Clear Tops, but the Sylvania and GE JAN tubes provide this bass kick with no problems.
added June 21st, 2005
Gain: Cryo-Vac Cryogenically treated RCA Cleartop 6CG7
Output: 2x RCA Cleartop 6CG7
This combination was brought to my attention after i first posted my review. I hadn't tried it as i didn't want to use tubes that i only have 2 examples of as gain, as i want to match the hours they were used as much as possible. This was a mistake, as this combination sounds great! It is right up there with the Sylvana+National Gold Line combo, but strikingly different. Whereas the Sylvania+National combo is smooth and warm, but fast and detailed, the Cryo+Cleartop combo is slightly cold, fast, extended and almost crystaline. It is a great combo, which really brings out detail and shimmers at the top end. It fixes the slight seperation problems that i had with the Cleartops, and they really sing. I think that the Cryos might just be too much when used as output with the CD3k's, and really shine when used as gain. The CD3k's are pretty treble heavy phones, so i think it's probably natural that the Cryos, which have extended, crisp treble, has an adverse effect when paied with the Sonys. I am now very much looking forward to trying the Cryos with slightly more laid back phones like the Sennheiser HD600's or 650's.
July 10, 2005 edit to the June 21st addition: I got used to the Cryos. i'm not sure what caused the discomfort I was feeling, but a couple weeks of acclimation fixed it. I no longer think the Cryos are "too much" when used in combination with the CD3k's, and I now very much like them.
added June 22nd, 2005
Gain: Cryo-Vac Cryogenically treated RCA Cleartop 6CG7
Output: 2x National Gold Line Matched 6CG7
This combination is great. The Nationals give the sound a smooth sweetness, while the Cryo Cleartop in the gain position keeps the extension and crystalline quality that i liked so much in the Cryo+Cleartop combo. I think that for lighter rock, acoustic, chamber music, etc, the Cryo+National combo is a great one, though i miss the "center mass" for Symphonic and harder rock music that the Sylvania+National combo gives.
I hope that this little review was helpful, and if anyone wants more specific details on any tube combo listed, or you would like me to review tube combinations not listed, let me know. Thanks for reading!
