Thank you for your detailed post. I actually have been listening to a G2504 and really like it.
Here's the AZ1 that I have (on the right) along with my AZ12:
LampizatOr Horizon - Tube Rolling Paradise
- Thread starter Golum
- Start date
Thank you for your detailed post. I actually have been listening to a G2504 and really like it.
Here's the AZ1 that I have (on the right) along with my AZ12:
Steve Williams
Site Founder, Site Co-Owner, Administrator
I found the G2504 is indeed a beast For my ears right now with the AZ12 the best I can describe it is that it is somewhere between the RGB 2004 and the Valvo G2504.
Glad you got solid plate for your G2504 as I found I preferred it over the mesh plate Valvo G2504
Glad you got solid plate for your G2504 as I found I preferred it over the mesh plate Valvo G2504
I haven’t tried either! I have been listening to the RGN2004 and 2054. The AZ1 and AZ12 are next.
Steve Williams
Site Founder, Site Co-Owner, Administrator
Those are my 3 favorite rectifiers David TFKN RGN 2005 mesh plate, Valvo G2504 Solid plate and TFKN AZ12 mesh plate. I have 4 of each of them so hopefully. a lifetime of fun
Hello, I am not Horizon user rather the Lampizator Golden Atlantic TRP, but if it can help I have tried more than 50 rectifiers and more than 100 big output (Pentodes, Tetrodes) tubes on Lampi.
I can see that most of Horizon users prefer big NOS pentodes like EL51, EL 156, 4654 which I also have found to be one of the best output tubes on my lampi. After trying various EL34 tubes (all Mullards, Telefunken double O getter, Ulm single getter, various RFT.....), and most of new prouction KTs I have totaly switched to EL50 family. But lets break it out by producers since I have find out that can sound very different in my system. Tesla EL51 was precious discovery after OS1 tubes, but only until I heard Philips EL51, and afterwards even better was Phillips 4654 metal base.
As far as rectifiers concern for a long time USAF 596 was my main rectifier but than I have switched to gz34 metal base and than to Marconi U18/20. In the meantime I have tried many different 5u4g and settled with Brimar U52. Than after a while tried Telefunken 4v series big mashed plate rectifiers (RGN 2504, 2004, 1054, 1064) which I found to be my favourites.
At the end I have settled with beautiful tetrode output WE 367a and CV378 Mullard rectifier. These are the best combos for my system:
1. Cv378 Mullard rectifier, 367a Western Electrics output
2. RGN1064 Telefunken mesh plate, EL 12 spec Telefunken output
3. USAF 596 rectifier, Phillips Miniwatt 4654 metal base
I can see that most of Horizon users prefer big NOS pentodes like EL51, EL 156, 4654 which I also have found to be one of the best output tubes on my lampi. After trying various EL34 tubes (all Mullards, Telefunken double O getter, Ulm single getter, various RFT.....), and most of new prouction KTs I have totaly switched to EL50 family. But lets break it out by producers since I have find out that can sound very different in my system. Tesla EL51 was precious discovery after OS1 tubes, but only until I heard Philips EL51, and afterwards even better was Phillips 4654 metal base.
As far as rectifiers concern for a long time USAF 596 was my main rectifier but than I have switched to gz34 metal base and than to Marconi U18/20. In the meantime I have tried many different 5u4g and settled with Brimar U52. Than after a while tried Telefunken 4v series big mashed plate rectifiers (RGN 2504, 2004, 1054, 1064) which I found to be my favourites.
At the end I have settled with beautiful tetrode output WE 367a and CV378 Mullard rectifier. These are the best combos for my system:
1. Cv378 Mullard rectifier, 367a Western Electrics output
2. RGN1064 Telefunken mesh plate, EL 12 spec Telefunken output
3. USAF 596 rectifier, Phillips Miniwatt 4654 metal base
Steve Williams
Site Founder, Site Co-Owner, Administrator
Thats what makes this hobby so much fun. There is no wrong answer but there really are so many right ones.
After a few rotations, I settled on this kit (SE user here) as the sweetspot between body, resolution, dynamics, organic texture. Happy camper since a few months now 
Steve Williams
Site Founder, Site Co-Owner, Administrator
Thats what I use as wellAfter a few rotations, I settled on this kit (SE user here) as the sweetspot between body, resolution, dynamics, organic texture. Happy camper since a few months now
Steve Williams
Site Founder, Site Co-Owner, Administrator
I have been using the Cossor 53KU (CV378) as my Lampi recti of choice for several years.
https://www.whatsbestforum.com/threads/lampizator-horizon-tube-rolling-paradise.34477/page-31 post #606
However, it should be well understood that not all CV378s are the same. In fact, the CV378 designation is somewhat confusing and does not identify a single tube type made by a single manufacturer. Some insight into the different CV378's can be found here:
GZ37, GZ33, 3KU, CV378, CV5745, U54, RECTIFIER, OCTAL
So, where to start with this valve type? Well, let’s take the Cossor 53KU often labelled CV378. Introduced in 1948, this octal based indirectly heated full wave rectifier in which the reservoir capacitor should never exceed 16μF and to avoid peak current spikes and minimum load series resistance...
mullard.org
The most surprising finding to me is that not all CV378s sound the same, in fact, far from it. In some cases, the sound differs widely, such as the supposed CV378 long, narrow bulb Mullard G37s, which I don't think are at the same level sonically as some others. After quite a bit if experimenting, my preference is for the staggered plate variant of the CV378 known as the 53KU made by Cossor in High Wycombe. The staggered plate GEC U52 is also excellent (made in Hammersmith, London and may be branded as either GEC, Osram, or Marconi).
https://www.whatsbestforum.com/thre...be-rolling-paradise.34477/page-44#post-881383 post #879
From my perspective, no 4V recti I have tried equals the 53KU/CV378 sonically and one reason why might be that the 53KU/CV378 does not require an adapter. (There's likely some merit to believing the best adapter is no adapter!). Every adapter undoubtedly has a sonic signture, whether its the "standard" Chinese gold plated pin adapters or even Laszlo's superb adapters which sound different depending on whether they are made with "standard" silver wire or Mundorf Angelique wire (my preference). My preference for the 53KU may also be due to its superb synergy with the Mullard ECC32 which is my preferred triode.
There is also an important caveat that must always be kept in mind which is that all tubes preferences are system and gear dependent. For example, while I prefer the 53KU Cossor on my H360, it was not my preferred recti on the Poseidon in which a 5Y3 worked beautifully and was preferred. Is it because the Poseidon uses 6N1P and 6J5 for amplification instead of 6SN7 triode/EL-34 type pentodes as does the H360? No idea. Nor do I think I will ever know. All I can say is that the staggered plate 53KU Cossar does the trick for me in the H360 with my other preferred tubes and has not been dethroned yet.
Last edited:
53ku is not cv378....totally different tubesI have been using the Cossor 53KU (CV378) as my Lampi recti of choice for several years.
https://www.whatsbestforum.com/threads/lampizator-horizon-tube-rolling-paradise.34477/page-31 post #606
However, it should be well understood that not all CV378s are the same. In fact, the CV378 designation is somewhat confusing and does not identify a single tube type made by a single manufacturer. Some insight into the different CV378's can be found here:
GZ37, GZ33, 3KU, CV378, CV5745, U54, RECTIFIER, OCTAL
So, where to start with this valve type? Well, let’s take the Cossor 53KU often labelled CV378. Introduced in 1948, this octal based indirectly heated full wave rectifier in which the reservoir capacitor should never exceed 16μF and to avoid peak current spikes and minimum load series resistance...mullard.org
The most surprising finding to me is that not all CV378s sound the same, in fact, far from it. In some cases, the sound differs widely, such as the supposed CV378 long, narrow bulb Mullard G37s, which I don't think are at the same level sonically as some others. After quite a bit if experimenting, my preference is for the staggered plate variant of the CV378 known as the 53KU made by Cossor in High Wycombe. The staggered plate GEC U52 is also excellent (made in Hammersmith, London and may be branded as either GEC, Osram, or Marconi).
https://www.whatsbestforum.com/thre...be-rolling-paradise.34477/page-44#post-881383 post #879
From my perspective, no 4V recti I have tried equals the 53KU/CV378 sonically and one reason why might be that the 53KU/CV378 does not require an adapter. (There's likely some merit to believing the best adapter is no adapter!). Every adapter undoubtedly has a sonic signture, whether its the "standard" Chinese gold plated pin adapters or even Laszlo's superb adapters which sound different depending on whether they are made with "standard" silver wire or Mundorf Angelique wire (my preference). My preference for the 53KU may also be due to its superb synergy with the Mullard ECC32 which is my preferred triode.
There is also an important caveat that must always be kept in mind which is that all tubes preferences are system and gear dependent. For example, while I prefer the 53KU Cossor on my H360, it was not my preferred recti on the Poseidon in which a 5Y3 worked beautifully and was preferred. Is it because the Poseidon uses 6N1P and 6J5 for amplification instead of 6SN7 triode/EL-34 type pentodes as does the H360? No idea. Nor do I think I will ever know. All I can say is that the staggered plate 53KU Cossar does the trick for me in the H360 with my other preferred tubes and has not been dethroned yet.
The mil spec cv378 is an indirectly heated tube
Interesting — I can use either (and not much of anything else) in my Art Audio Jota amps. Radiomuseum claims they are equal. Is this not true?
Ian,
Sorry but your information is not quite correct, To begin, the CV378 is indeed a indirectly heated filament. So is the 53KU but as I stated clearly, "In fact, the CV378 designation is somewhat confusing and does not identify a single tube type made by a single manufacturer. Of course the CV378 and 53KU tubes aren't identical (they can be made in different factories Hammersmith and High Wycombe respectively, even though both are owned by Miullard). However, for the most part, CV378 is essentially the same as 53KU. They are different names/labels for the same full-wave rectifier tube. CV378 and 53KU are essentially electrically equivalent in all the major operating parameters: heater voltage/current, max current, allowed capacitor, etc.
· CV378 is the military/specification code. r-type.org+2MULLARD MAGIC+2
· 53KU is one of the commercial/model names for the same tube. MULLARD MAGIC+2nosvacuumtubes.net+2
· Other equivalent names include GZ37, U54, GZ33 depending on manufacturer or form. audioasylum.com+3MULLARD MAGIC+3r-type.org+3
Additional Details / Confirmations
- CV378 is explicitly listed as “full wave rectifier” and is said to be “identical to CV378 = U54 = 53KU = GZ37” in several sources. Radiomuseum+2Radiomuseum+2
- Physical size: the envelope is about 44 mm diameter, height around 126-127 mm excluding base pins. tdsl.duncanamps.com+3r-type.org+3r-type.org+3
- It uses an Octal base (IO base / terminal base) – makes it fairly standardized in that respect.
in short, CV378 is essentially the same as 53KU, along with several other designations. They are different names/labels for the same full-wave rectifier tube. So yes, they are different tubes possibly made in different factories, but they are electrically identical.
The more interesting question for me is not whether they are essentially the same tube and clearly direct substitutes for each other, but does the mil spec CV378 (typically black base) sound any different than the 53KU (typically brown base)? I have about 9 of these tubes, 4 x CV378 and 5x 53KU. I have not been impressed that there are many significant qualitative differences between the staggered plate versions of either tube type. By the way the mil spec vs non mil spec comparison is a similar for the triode family Mullard ECC32 vs the mil spec equivalent CV181. The Mullard (brown bases) and CV181 (typically black base) sound essentially identical as far as I can tell. The only reason to try and obtain the mil spec version of either tube is that their QC is said to be a bit better (and typical of mil spec) but this is possibly conjecture. It is however, often mentioned as a reason they often cost a bit more. Honestly, who knows?
Marty
Last edited:
i think we need to look past the labelling here. for eg is shuguang 5u4g the same as an rca ? - serial numbers dont mean much when you look into the construction. i am a tube admin on radiomusum - by equal we mean electrical equivalency not physical equivalency. true mil spec cv378 are copper plates on the inside and a small tube . true 53ku is a fat tube and made by cossor
Last edited:
I just finished my C3g/Lundahl phono stage two days ago. It's best sounding I ever heard in my life so far.
Similar threads
 | Steve Williams Site Founder | Site Owner | Administrator |  | Ron Resnick Site Owner | Administrator |  | Julian (The Fixer) Website Build | Marketing Managersing |