LampizatOr Horizon - Tube Rolling Paradise

[steve williams]

well its been over a year since I received my Horizon and for most of that time my preferred tube set has been TS KT170, TungSol 6SN7GT VT231 with round plate and black glass along with the fabled Takatsuki 274B rectifier. These three tubes in my room and with my 32 wpm Class A SET gear have produced sonic bliss contrary to many of the comments here . What is readily evident is that tube rolling to me is tantamount to changing cartridges to listen to vinyl. It is all system specific and user preference. Adding the KT 170 enhanced over all sonic and the Takatsuki added a very tight and articulate deep bass whereas the TS 6SN7GT added so much more detail that at the end of the day I was very happy. The one thing however that was always on my mind was that as good as the Tak 274B is , t impart a dark texture to the music. Further I was quite interested that several users found distortion at higher levels with the TS KT170. This is something that I also noticed but it never really bothered me because I rarely plated at high levels. So along the way as I stay current with this thread I have read some things which caught my interest

1. Sampajanna constantly commenting about his strongly positive thoughts about the Mullard ECC32 Brown base vs my favored TS 6SN7GT

2. The general feeling that as much as I loved the Tak 274B it does impart a darkness to the sonic impression

3. The fact that the KT 170 has audible distortion.

4. My friendship with Goran and Laszlo and over the years their recommendations are always something I pay heed to

Hence over the past 4-5 weeks I have systematically changed each tube kind with their preferred and the following chronicles my impressions. FWIW, I remain still very partial to the TS 6SN7 GT as well as the Tak 274B but along the way David and his slingshot have squashed my Goliath

Firstly I became very interested in the Tungsram OS1 (needs adapters) after many conversations with Laszlo and Goran. I had this ache in my chest knowing that any time I talk to either, it costs me $$$

All after due consideration I felt obligated to check this tube out and found 2 perfectly matched NOS quad sets (I will use only a pair rather than the quad as I run the Horizon single ended-I put a pair ok TS KT 170 in the right bank of pentodes . I was also fortunate enough to find adapters for these tubes. So 4-5 weeks ago the KT170 was removed and the Tungsram OS1 was inserted. Day 1 of listening imparted a very beautiful and open midrange which I had not heard with the KT170 but the deep bass and tightness of such was no where as good as the KT170. I had my doubts but this was day 1. The tubes were played for the rest of the day and on day 2 I began hearing some of the magic of the OS1. The bass was beginning to sound much more articulate and tight but it was the openness of the midrange and the top end which caught my interest. By day 3 the tube was sending like nothing Ive heard in my system. Gone was the distortion I heard from the KT170 played at high volume. There was an ease of presentation. I hate to use the word "natural" but for my ears I was indeed hearing something that sounded somewhat darker wit the KT 170 than what I prefer. The OS1 over the past 5 weeks has continued to open and it is a sound that is truly breathtaking even with my Tak 274B



2. The biggest tube which totally blew me away was the swapping of the Tak 274B for a 90year old rectifier from 1934, the Telefunken RGN 2004 Klangfilm. This is a 4 volt tube and requires a special adapter containing a resistor which steps down the voltage from 5v to 4v. There are adapters for this tube to fit the Horizon but noe of these adapters contain this resistor. Again I was fortunate enough to obtain the proper adapter. In a few short words, this rectifier changed my concept completely of my preferred sound. This is a fabulous rectifier so much so that I also found a back up as this is a rectifier that is open, airy, natural but with simply beautiful bottom end. Nothing is colored as it sounds top to bottom neutral and without coloration. There are many versions of this tube but it is this one from 1934 that will make your jaw drop. The blackness from the Tak 274B was gone and everything sounded better than what Ive heard. This rectifier has been in my system now for the past 2 weeks and it is a keeper. The sound was beautiful even with my TS 6SN7 GT



This tube when powered on imparts the most beautiful blue purple color that is a joy to watch



Finally I come back to to Sampajanna's comments about the Mullard brown base ECC32 that he felt it always trumped my TS 6SN7GT. It was no easy task finding this storied tube but I found 2 sets measuring strong and a 3rd set that is made by Mullard but branded Chelmer . So bottom line these have been in now for this past week and there is no question that Sampajanna is dead on with his evaluation. Adding this tube was the icing on the cake. No adapters needed. The dynamics and presentation is simply explosive. it is so organic with a sense of reality that I feel the musicians and singers to be in the room with me.

To get back to tube rolling and deciding what is right is not always the same for two different systems and rooms but what these 3 new tubes added to my overall sonic experience was like nothing have ever heard before. So when I say I am not a tube roller, I have been pulled back in but when Goran and Laszlo talk , people listen ( I know I did). I now have this as my preferred tube kit and continue to keep the KT 170, TS 6SN7 and Tak 274B as a back up tube kit.

IIRC it was Sampajanna who stated not to skip on the price of tubes when playing a $50K Horizon DAC. I tend to agree (wish it weren't so) as these 3 tubes along with back ups, adapters and special adapter has set me back $6800. For me this was quite a stretch but the synergy imparted to the sound fro these three tubes is beyond what I've ever heard thanks to Goran and Laszlo who always find the Magic Bullet to pull me back in

 

[steve williams]

I usually put this storied quote up when I refer to Emile but the same quote applies to Goran and Laszlo when it comes to tube rolling and system synergy and also thanks to Sampajanna

 

[Golum]

Very very nice report Steve and I'm glad you love the end result. Synergy of this trio of tubes is just amazing.

 

[hifirabbit]

well its been over a year since I received my Horizon and for most of that time my preferred tube set has been TS KT170, TungSol 6SN7GT VT231 with round plate and black glass along with the fabled Takatsuki 274B rectifier. These three tubes in my room and with my 32 wpm Class A SET gear have produced sonic bliss contrary to many of the comments here . What is readily evident is that tube rolling to me is tantamount to changing cartridges to listen to vinyl. It is all system specific and user preference. Adding the KT 170 enhanced over all sonic and the Takatsuki added a very tight and articulate deep bass whereas the TS 6SN7GT added so much more detail that at the end of the day I was very happy. The one thing however that was always on my mind was that as good as the Tak 274B is , t impart a dark texture to the music. Further I was quite interested that several users found distortion at higher levels with the TS KT170. This is something that I also noticed but it never really bothered me because I rarely plated at high levels. So along the way as I stay current with this thread I have read some things which caught my interest

1. Sampajanna constantly commenting about his strongly positive thoughts about the Mullard ECC32 Brown base vs my favored TS 6SN7GT

2. The general feeling that as much as I loved the Tak 274B it does impart a darkness to the sonic impression

3. The fact that the KT 170 has audible distortion.

4. My friendship with Goran and Laszlo and over the years their recommendations are always something I pay heed to

Hence over the past 4-5 weeks I have systematically changed each tube kind with their preferred and the following chronicles my impressions. FWIW, I remain still very partial to the TS 6SN7 GT as well as the Tak 274B but along the way David and his slingshot have squashed my Goliath

Firstly I became very interested in the Tungsram OS1 (needs adapters) after many conversations with Laszlo and Goran. I had this ache in my chest knowing that any time I talk to either, it costs me $$$

All after due consideration I felt obligated to check this tube out and found 2 perfectly matched NOS quad sets (I will use only a pair rather than the quad as I run the Horizon single ended-I put a pair ok TS KT 170 in the right bank of pentodes . I was also fortunate enough to find adapters for these tubes. So 4-5 weeks ago the KT170 was removed and the Tungsram OS1 was inserted. Day 1 of listening imparted a very beautiful and open midrange which I had not heard with the KT170 but the deep bass and tightness of such was no where as good as the KT170. I had my doubts but this was day 1. The tubes were played for the rest of the day and on day 2 I began hearing some of the magic of the OS1. The bass was beginning to sound much more articulate and tight but it was the openness of the midrange and the top end which caught my interest. By day 3 the tube was sending like nothing Ive heard in my system. Gone was the distortion I heard from the KT170 played at high volume. There was an ease of presentation. I hate to use the word "natural" but for my ears I was indeed hearing something that sounded somewhat darker wit the KT 170 than what I prefer. The OS1 over the past 5 weeks has continued to open and it is a sound that is truly breathtaking even with my Tak 274B

View attachment 108964

2. The biggest tube which totally blew me away was the swapping of the Tak 274B for a 90year old rectifier from 1934, the Telefunken RGN 2004 Klangfilm. This is a 4 volt tube and requires a special adapter containing a resistor which steps down the voltage from 5v to 4v. There are adapters for this tube to fit the Horizon but noe of these adapters contain this resistor. Again I was fortunate enough to obtain the proper adapter. In a few short words, this rectifier changed my concept completely of my preferred sound. This is a fabulous rectifier so much so that I also found a back up as this is a rectifier that is open, airy, natural but with simply beautiful bottom end. Nothing is colored as it sounds top to bottom neutral and without coloration. There are many versions of this tube but it is this one from 1934 that will make your jaw drop. The blackness from the Tak 274B was gone and everything sounded better than what Ive heard. This rectifier has been in my system now for the past 2 weeks and it is a keeper. The sound was beautiful even with my TS 6SN7 GT

View attachment 108965

This tube when powered on imparts the most beautiful blue purple color that is a joy to watch

View attachment 108966

Finally I come back to to Sampajanna's comments about the Mullard brown base ECC32 that he felt it always trumped my TS 6SN7GT. It was no easy task finding this storied tube but I found 2 sets measuring strong and a 3rd set that is made by Mullard but branded Chelmer . So bottom line these have been in now for this past week and there is no question that Sampajanna is dead on with his evaluation. Adding this tube was the icing on the cake. No adapters needed. The dynamics and presentation is simply explosive. it is so organic with a sense of reality that I feel the musicians and singers to be in the room with me.

To get back to tube rolling and deciding what is right is not always the same for two different systems and rooms but what these 3 new tubes added to my overall sonic experience was like nothing have ever heard before. So when I say I am not a tube roller, I have been pulled back in but when Goran and Laszlo talk , people listen ( I know I did). I now have this as my preferred tube kit and continue to keep the KT 170, TS 6SN7 and Tak 274B as a back up tube kit.

IIRC it was Sampajanna who stated not to skip on the price of tubes when playing a $50K Horizon DAC. I tend to agree (wish it weren't so) as these 3 tubes along with back ups, adapters and special adapter has set me back $6800. For me this was quite a stretch but the synergy imparted to the sound fro these three tubes is beyond what I've ever heard thanks to Goran and Laszlo who always find the Magic Bullet to pull me back in

View attachment 108967


View attachment 108969

Hi Steve
Where can you order the special adapters?
Best

 

[plasmod3]

well its been over a year since I received my Horizon and for most of that time my preferred tube set has been TS KT170, TungSol 6SN7GT VT231 with round plate and black glass along with the fabled Takatsuki 274B rectifier. These three tubes in my room and with my 32 wpm Class A SET gear have produced sonic bliss contrary to many of the comments here . What is readily evident is that tube rolling to me is tantamount to changing cartridges to listen to vinyl. It is all system specific and user preference. Adding the KT 170 enhanced over all sonic and the Takatsuki added a very tight and articulate deep bass whereas the TS 6SN7GT added so much more detail that at the end of the day I was very happy. The one thing however that was always on my mind was that as good as the Tak 274B is , t impart a dark texture to the music. Further I was quite interested that several users found distortion at higher levels with the TS KT170. This is something that I also noticed but it never really bothered me because I rarely plated at high levels. So along the way as I stay current with this thread I have read some things which caught my interest

1. Sampajanna constantly commenting about his strongly positive thoughts about the Mullard ECC32 Brown base vs my favored TS 6SN7GT

2. The general feeling that as much as I loved the Tak 274B it does impart a darkness to the sonic impression

3. The fact that the KT 170 has audible distortion.

4. My friendship with Goran and Laszlo and over the years their recommendations are always something I pay heed to

Hence over the past 4-5 weeks I have systematically changed each tube kind with their preferred and the following chronicles my impressions. FWIW, I remain still very partial to the TS 6SN7 GT as well as the Tak 274B but along the way David and his slingshot have squashed my Goliath

Firstly I became very interested in the Tungsram OS1 (needs adapters) after many conversations with Laszlo and Goran. I had this ache in my chest knowing that any time I talk to either, it costs me $$$

All after due consideration I felt obligated to check this tube out and found 2 perfectly matched NOS quad sets (I will use only a pair rather than the quad as I run the Horizon single ended-I put a pair ok TS KT 170 in the right bank of pentodes . I was also fortunate enough to find adapters for these tubes. So 4-5 weeks ago the KT170 was removed and the Tungsram OS1 was inserted. Day 1 of listening imparted a very beautiful and open midrange which I had not heard with the KT170 but the deep bass and tightness of such was no where as good as the KT170. I had my doubts but this was day 1. The tubes were played for the rest of the day and on day 2 I began hearing some of the magic of the OS1. The bass was beginning to sound much more articulate and tight but it was the openness of the midrange and the top end which caught my interest. By day 3 the tube was sending like nothing Ive heard in my system. Gone was the distortion I heard from the KT170 played at high volume. There was an ease of presentation. I hate to use the word "natural" but for my ears I was indeed hearing something that sounded somewhat darker wit the KT 170 than what I prefer. The OS1 over the past 5 weeks has continued to open and it is a sound that is truly breathtaking even with my Tak 274B

View attachment 108964

2. The biggest tube which totally blew me away was the swapping of the Tak 274B for a 90year old rectifier from 1934, the Telefunken RGN 2004 Klangfilm. This is a 4 volt tube and requires a special adapter containing a resistor which steps down the voltage from 5v to 4v. There are adapters for this tube to fit the Horizon but noe of these adapters contain this resistor. Again I was fortunate enough to obtain the proper adapter. In a few short words, this rectifier changed my concept completely of my preferred sound. This is a fabulous rectifier so much so that I also found a back up as this is a rectifier that is open, airy, natural but with simply beautiful bottom end. Nothing is colored as it sounds top to bottom neutral and without coloration. There are many versions of this tube but it is this one from 1934 that will make your jaw drop. The blackness from the Tak 274B was gone and everything sounded better than what Ive heard. This rectifier has been in my system now for the past 2 weeks and it is a keeper. The sound was beautiful even with my TS 6SN7 GT

View attachment 108965

This tube when powered on imparts the most beautiful blue purple color that is a joy to watch

View attachment 108966

Finally I come back to to Sampajanna's comments about the Mullard brown base ECC32 that he felt it always trumped my TS 6SN7GT. It was no easy task finding this storied tube but I found 2 sets measuring strong and a 3rd set that is made by Mullard but branded Chelmer . So bottom line these have been in now for this past week and there is no question that Sampajanna is dead on with his evaluation. Adding this tube was the icing on the cake. No adapters needed. The dynamics and presentation is simply explosive. it is so organic with a sense of reality that I feel the musicians and singers to be in the room with me.

To get back to tube rolling and deciding what is right is not always the same for two different systems and rooms but what these 3 new tubes added to my overall sonic experience was like nothing have ever heard before. So when I say I am not a tube roller, I have been pulled back in but when Goran and Laszlo talk , people listen ( I know I did). I now have this as my preferred tube kit and continue to keep the KT 170, TS 6SN7 and Tak 274B as a back up tube kit.

IIRC it was Sampajanna who stated not to skip on the price of tubes when playing a $50K Horizon DAC. I tend to agree (wish it weren't so) as these 3 tubes along with back ups, adapters and special adapter has set me back $6800. For me this was quite a stretch but the synergy imparted to the sound fro these three tubes is beyond what I've ever heard thanks to Goran and Laszlo who always find the Magic Bullet to pull me back in

View attachment 108967


View attachment 108969

Amazing ! So good to hear the you got the tubes and they work well Steve. As mentioned these tubes had GM scores of more than 130% . Ie very very strong true nos

 

[Sablon Audio]

Hi Steve
Where can you order the special adapters?
Best

Is that Wai Lee? You can get the adaptors on ebay. There’s a chinese seller called xulingmrs who sells lots of different adapters and the b4 type socket needed for the rgn series (and many other vintage 4 volt rectifier models) can be further customised with different value resistors to suit the heater filament current requirements of types 1054 / 1064 / 2004 / 2504 / 4004 (and pv200/600) if you tell him which valve you plan on using. The 2.3a of 2004 is pretty widely used through.

 

[hifirabbit]

Is that Wai Lee? You can get the adaptors on ebay. There’s a chinese seller called xulingmrs who sells lots of different adapters and the b4 type socket needed for the rgn series (and many other vintage 4 volt rectifier models) can be further customised with different value resistors to suit the heater filament current requirements of types 1054 / 1064 / 2004 / 2504 / 4004 (and pv200/600) if you tell him which valve you plan on using. The 2.3a of 2004 is pretty widely used through.

Hi Mark,
Thanks for the quick reply!
So the Horizon rectifier needs 5 volts and one needs to order the adapter for the 2004 rectifier to be used?
What resistor value should one specify when one orders?
Best

 

[Sablon Audio]

Hi Wai Lee, this is the link you want though I would also recommend asking for a second unit tailored for pv200/600 as that is a great alternative available for pocket money and a lot more easily found than the globe silver mesh rgn2004

1pc Gold plated RGN2004 TO 5Y3 5U4G 5AR4 5Z3P tube converter adapter | eBay

1pc Gold plated RGN2004 TO 5Y3 5U4G 5AR4 5Z3P tube converter adapter | Consumer Electronics, Vintage Electronics, Vintage Audio & Video | eBay!

www.ebay.com.my

 

[Sablon Audio]

This overview from the emission labs site gives a helpful summary of the heater current draw and output of the various RGN valve types. Pv200/600 actually measures more like 4004.

 

[steve williams]

A different source at this end and I have no idea which resistor is in the adapter I purchased. The one takeaway is that this rectifier from 1934 is truly a system changer but the overall synergy with this tube set takes my system into a place I never thought existed. I love the Tak 274B and will keep it for now but the naturalness of the sound this RGN 2004 rectifier produces is truly a game changer. Plus I love watching the flash of blue color when the tube is powered on

 

[steve williams]

When commenting on this tube set I made the changes one by one over a period of 4-5 weeks. Each tube imparts a much different flavor than what I was using . The OS1 when compared ti the KT170 was for my ears quite revelational as there was an ease to the presentation as well as an openness which was not there with. the KT170. AS stated there was indeed distortion when playing at louder SPL but the OS1displayed no distortion, it is tonally balanced from top to bottom and playing at louder levels caused no fatigue, distortion or coloration. Everything comes to gather in one neat package when the Mullard ECC32 is added. The dynamics are tight and explosive and the synergy makes this tube set one which cannot be ignored. I was using the Tungsram tubes as a quad. I do have an excellent back up set but to play it safelyI am using the OS1 now as a pair in the left bank only as I run single ended. I place two of my KT170's in the right bank which doesn't sit well with my OCD personality until I take into consideration the price of these tubes, this tube set and the backup sets I was able to procure. This was a huge investment on my part but with the addition of each of the 3 different tubes into my system I could not turn my head away.

 

[Sampajanna]

I am still moving things around and settling, but the process Has been fun and I think the end is in sight for me. Steve has done a wonderful job in this report. He is far more articulate than me. I really appreciate it. I laughed and nodded away while reading.

 

[heihei]

Anyone tried EAT KT88 valves in their Horizon?

 

[marty]

AZ1 vs AZ4 4V Mesh rectifiers for Horizon

There has been some recent interest in using 4V rectifiers in the Horizon instead of the more common 5V rectifiers that are typically used (and supplied by the factory with new units). While these 4V rectifiers come in both plate and mesh versions, the experience of several users suggest it is the mesh versions that are sonically superior, so I tried some of these in my Horizon over the past month or so and am happy to share my experience.

The AZ1 is a directly heated full wave rectifier and is fitted with an eight pin side contact base. These bases were used originally by Philips in Europe and Mullard in the UK for universal valves from the 1930s. It has a 4?Volt filament rated at 1.1?Amp. Historically, AZ4 was part of a newer generation rectifier tubes (1953), following up the famous RGN Series of Telefunken, and was intended for applications the AZ1 by Philips, could not do. AZ4 is in between 274B and 5U4G.

The specs can be seen easily in table form below






More detailed info from the PDFs at Tube Museum show more detailed differences

AZ1 (RGN1004)



AZ4 (RGN2004)




From this data you can see why the AZ1 is a directly heated full wave rectifier that was developed for medium powered receivers operating on normal working voltages, whereas the AZ4 was for receivers using heavy current. Physically, they are easy to tell apart in their mesh variation as the AZ1 has a single “V” filament that is visible in the plates whereas the AZ4 has a double “V” filament visible.

I tried the AZ1 but it was short lived in my system. It had an appealing upper midrange with a silkiness that is often characteristic of mesh rectifiers, and the very bottom was full and had good definition., However I thought the mid-bass and upper bass was a bit anemic in my system and this did not translate well to orchestral reproduction as the lower brass, (as well as male vocals) were just a bit light for my taste. I sold it immediately and moved on to the AZ4.

The AZ4 (RGN2004) I used was a NIB Valvo that as far as I can tell had the same base engravature as the TFKN and may have been made on the same factory (both are of course German companies). The AZ4 was a far more satisfactory performer in my system than the AZ1. (And that double “V” is a thing a beauty to tube-a-holics). The main objection I had with the lack of fullness and weight of the orchestra with the AZ1 was largely relieved using the RGN 2004, but not completely. As much as I wanted to like this tube, I ultimately couldn’t embrace its overall balance in comparison to my preferred GEC staggered plate U52 variant (53KU Cossor/GEC/MOV- different labels but all made in High Wycombe which is the key). The RGN2004 was just not as full sounding in my system. With prolonged listening, I found little not to like otherwise with the RGN2004, but then a came across a passage on Snow Maiden (Reference Recordings) where there was an instrument I could not easily identify until I put back my Cossor and then heard very distinctly that it was a tambourine which simply was not easily identified with the RGN2004. In general the clarity of the high end, and the air of the hall on many recoprdings was better rendered with the 53KU (some of this may be certainly be speaker or tweeter dependent and of course YMMV). The net result is that I sold my RGN2004 because not only did I find the 53KU a better sounding and balanced overall tube in my system, but the cost of the RGN2004 is extremely expensive (>1K+ in mint NOS condition) and is very hard to find whereas the GEC52 family in general is far more plentiful and typically less than half the price.

I would add that some tube experts have said that the problem with the RGN2004 is not necessarily the tube, but the adapter that is used. There is speculation that the resistor used in the base is not of particularly high quality and causes the adapter to overheat, which may effect performance. However, since the only available adapter I could find was a $27 Chinese adapter on Ebay, it’s the only one I used for my evaluation. No doubt that the RGN2004 is a very good tube, and it's possible that with a better adapter (by Woo? or someone else), my thoughts might change. But for now, it was just not for me.

 

[takacs75]

AZ1 vs AZ4 4V Mesh rectifiers for Horizon

There has been some recent interest in using 4V rectifiers in the Horizon instead of the more common 5V rectifiers that are typically used (and supplied by the factory with new units). While these 4V rectifiers come in both plate and mesh versions, the experience of several users suggest it is the mesh versions that are sonically superior, so I tried some of these in my Horizon over the past month or so and am happy to share my experience.

The AZ1 is a directly heated full wave rectifier and is fitted with an eight pin side contact base. These bases were used originally by Philips in Europe and Mullard in the UK for universal valves from the 1930s. It has a 4?Volt filament rated at 1.1?Amp. Historically, AZ4 was part of a newer generation rectifier tubes (1953), following up the famous RGN Series of Telefunken, and was intended for applications the AZ1 by Philips, could not do. AZ4 is in between 274B and 5U4G.

The specs can be seen easily in table form below

View attachment 110717


View attachment 110718

More detailed info from the PDFs at Tube Museum show more detailed differences

AZ1 (RGN1004)

View attachment 110719

AZ4 (RGN2004)

View attachment 110720
View attachment 110721

From this data you can see why the AZ1 is a directly heated full wave rectifier that was developed for medium powered receivers operating on normal working voltages, whereas the AZ4 was for receivers using heavy current. Physically, they are easy to tell apart in their mesh variation as the AZ1 has a single “V” filament that is visible in the plates whereas the AZ4 has a double “V” filament visible.

I tried the AZ1 but it was short lived in my system. It had an appealing upper midrange with a silkiness that is often characteristic of mesh rectifiers, and the very bottom was full and had good definition., However I thought the mid-bass and upper bass was a bit anemic in my system and this did not translate well to orchestral reproduction as the lower brass, (as well as male vocals) were just a bit light for my taste. I sold it immediately and moved on to the AZ4.

The AZ4 (RGN2004) I used was a NIB Valvo that as far as I can tell had the same base engravature as the TFKN and may have been made on the same factory (both are of course German companies). The AZ4 was a far more satisfactory performer in my system than the AZ1. (And that double “V” is a thing a beauty to tube-a-holics). The main objection I had with the lack of fullness and weight of the orchestra with the AZ1 was largely relieved using the RGN 2004, but not completely. As much as I wanted to like this tube, I ultimately couldn’t embrace its overall balance in comparison to my preferred GEC staggered plate U52 variant (53KU Cossor/GEC/MOV- different labels but all made in High Wycombe which is the key). The RGN2004 was just not as full sounding in my system. With prolonged listening, I found little not to like otherwise with the RGN2004, but then a came across a passage on Snow Maiden (Reference Recordings) where there was an instrument I could not easily identify until I put back my Cossor and then heard very distinctly that it was a tambourine which simply was not easily identified with the RGN2004. In general the clarity of the high end, and the air of the hall on many recoprdings was better rendered with the 53KU (some of this may be certainly be speaker or tweeter dependent and of course YMMV). The net result is that I sold my RGN2004 because not only did I find the 53KU a better sounding and balanced overall tube in my system, but the cost of the RGN2004 is extremely expensive (>1K+ in mint NOS condition) and is very hard to find whereas the GEC52 family in general is far more plentiful and typically less than half the price.

I would add that some tube experts have said that the problem with the RGN2004 is not necessarily the tube, but the adapter that is used. There is speculation that the resistor used in the base is not of particularly high quality and causes the adapter to overheat, which may effect performance. However, since the only available adapter I could find was a $27 Chinese adapter on Ebay, it’s the only one I used for my evaluation. No doubt that the RGN2004 is a very good tube, and it's possible that with a better adapter (by Woo? or someone else), my thoughts might change. But for now, it was just not for me.

You have right Marty. With the chinese adapter the RGN2004 is just a good tube. The adapter is built with the wrong resistor, which cause extreme heat inside the adapter. Guess what happens with the resistance in this hot enviroment. With the right adapter it is the finest sounding recti I’ve ever heard. I also have a GEC U52, which was one of my favorite recti. In my system I prefer the RGN over the GEC. You should try a Telefunken/Klangfilm RGN2004 with the right adapter

 

[marty]

You have it right Marty. With the chinese adapter the RGN2004 is just a good tube. The adapter is built with the wrong resistor, which cause extreme heat inside the adapter. Guess what happens with the resistance in this hot environment. With the right adapter it is the finest sounding recti I’ve ever heard. I also have a GEC U52, which was one of my favorite recti. In my system I prefer the RGN over the GEC. You should try a Telefunken/Klangfilm RGN2004 with the right adapter

I would not disagree. The issue then, is where does one find the "right adapter" if not from "adapter-man" that we all use on ebay? Also, most GEC U52s have parallel plates, not staggered plates so I'd be curious about which GEC U52 specifically you used for comparison.

 

[takacs75]

I would not disagree. The issue then, is where does one find the "right adapter" if not from "adapter-man" that we all use on ebay? Also, most GEC U52s have parallel plates, not staggered plates so I'd be curious about which GEC U52 specifically you used for comparison.

 

[steve williams]

Woo does not make adapters with resistors.

 

[marty]

View attachment 110725

Thank you. I have the identical tube as well. Parallel plates. Very different physically and sonically than the High Wycombe staggered plate variant such as the 53KU Cossor/Osram/GEC. I never expected these tubes to be sonically different but was alerted to this by reading some critical reviews of these variants that were written decades ago (Lord only knows what gear was used to conduct these comparisons back then?) . The tubes are sonically nearly identical but the staggered plate version was thought to have "better" bass, which is what I have found as well. Here are some examples:

GEC staggered plate- the plates are in the same plane but staggered, perhaps better appreciated from the top view



MWT parallel plate- (the most common type of U52). The plates are well separated and at the far sides of the bulb.



Cossor 53KU/Osram CV378- once again, staggered plates. As far as I can tell, all the GEC/MOV/Osram staggered plates were made in the MOV factory in High Wycombe which is designated as "K" on the glass or box.



All excellent and beautiful tubes. Whatever works for you is good. Can't go wrong with any of these.

If you would kindly suggest the "ne ultimate plus" RGN2004 adapter, I'll gladly revisit that tube again but for now, I'm in the "if it ain't broke, don't fix it" space for my Horizon tube set.

 

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AZ1 vs AZ4 4V Mesh rectifiers for Horizon

There has been some recent interest in using 4V rectifiers in the Horizon instead of the more common 5V rectifiers that are typically used (and supplied by the factory with new units). While these 4V rectifiers come in both plate and mesh versions, the experience of several users suggest it is the mesh versions that are sonically superior, so I tried some of these in my Horizon over the past month or so and am happy to share my experience.

The AZ1 is a directly heated full wave rectifier and is fitted with an eight pin side contact base. These bases were used originally by Philips in Europe and Mullard in the UK for universal valves from the 1930s. It has a 4?Volt filament rated at 1.1?Amp. Historically, AZ4 was part of a newer generation rectifier tubes (1953), following up the famous RGN Series of Telefunken, and was intended for applications the AZ1 by Philips, could not do. AZ4 is in between 274B and 5U4G.

The specs can be seen easily in table form below

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More detailed info from the PDFs at Tube Museum show more detailed differences

AZ1 (RGN1004)

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AZ4 (RGN2004)

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From this data you can see why the AZ1 is a directly heated full wave rectifier that was developed for medium powered receivers operating on normal working voltages, whereas the AZ4 was for receivers using heavy current. Physically, they are easy to tell apart in their mesh variation as the AZ1 has a single “V” filament that is visible in the plates whereas the AZ4 has a double “V” filament visible.

I tried the AZ1 but it was short lived in my system. It had an appealing upper midrange with a silkiness that is often characteristic of mesh rectifiers, and the very bottom was full and had good definition., However I thought the mid-bass and upper bass was a bit anemic in my system and this did not translate well to orchestral reproduction as the lower brass, (as well as male vocals) were just a bit light for my taste. I sold it immediately and moved on to the AZ4.

The AZ4 (RGN2004) I used was a NIB Valvo that as far as I can tell had the same base engravature as the TFKN and may have been made on the same factory (both are of course German companies). The AZ4 was a far more satisfactory performer in my system than the AZ1. (And that double “V” is a thing a beauty to tube-a-holics). The main objection I had with the lack of fullness and weight of the orchestra with the AZ1 was largely relieved using the RGN 2004, but not completely. As much as I wanted to like this tube, I ultimately couldn’t embrace its overall balance in comparison to my preferred GEC staggered plate U52 variant (53KU Cossor/GEC/MOV- different labels but all made in High Wycombe which is the key). The RGN2004 was just not as full sounding in my system. With prolonged listening, I found little not to like otherwise with the RGN2004, but then a came across a passage on Snow Maiden (Reference Recordings) where there was an instrument I could not easily identify until I put back my Cossor and then heard very distinctly that it was a tambourine which simply was not easily identified with the RGN2004. In general the clarity of the high end, and the air of the hall on many recoprdings was better rendered with the 53KU (some of this may be certainly be speaker or tweeter dependent and of course YMMV). The net result is that I sold my RGN2004 because not only did I find the 53KU a better sounding and balanced overall tube in my system, but the cost of the RGN2004 is extremely expensive (>1K+ in mint NOS condition) and is very hard to find whereas the GEC52 family in general is far more plentiful and typically less than half the price.

I would add that some tube experts have said that the problem with the RGN2004 is not necessarily the tube, but the adapter that is used. There is speculation that the resistor used in the base is not of particularly high quality and causes the adapter to overheat, which may effect performance. However, since the only available adapter I could find was a $27 Chinese adapter on Ebay, it’s the only one I used for my evaluation. No doubt that the RGN2004 is a very good tube, and it's possible that with a better adapter (by Woo? or someone else), my thoughts might change. But for now, it was just not for me.

Looking at the curves, we can see that the AZ1 and AZ4 have very different I, V characteristics and that the audio tubes will be operated at different points of operation. I consider that designers choose properly and optimize the point of operation of their circuits. What is the point of such big changes? I think that tube rolling is an interesting aspect of the hobby, but IMO should be done keeping the electrical properties of tubes, using equivalent or close equivalent tubes.