[UntilThen]

Forget about George Costanza. Let me introduce you to your next headphone / speaker amp.

 

[attmci]

@gibosi is this a Sylvania? I am interested in buying 6.
https://www.ebay.com.au/itm/Silvert...417577&hash=item28543f2abf:g:saIAAOSwOy1aplIN

312, 312, 312 is the code.

OK, Ken already answered. Just saw.

 

[UntilThen]

312, 312, 312 is the code.

OK, Ken already answered. Just saw.

Stop giving out my bank account number.

 

[gibosi]

For those who have some interest in tube rectifiers.....

A number of folks in this forum subscribe to the theory that rectifiers have no sound. They believe that any and all sonic changes resulting from rolling rectifiers is due to a change in voltage drop, which changes B+, which alters the operating points of the other tubes in the circuit. Again this is a theory. Some people believe it and others don't. And I have seen nothing in writing which attempts to prove or disprove this theory.

In the end, from my perspective, if a theory is useful and helps me understand the "sound" of rectifiers, it is a good theory. And if it doesn't fit reality as I experience it, it's a lousy theory and I dismiss it.

Fortunately, it is very easy to test this theory. All that is necessary is decent sized collection of rectifiers and a volt meter and it just so happens that I have both of these. A couple years ago, I measured the voltage drop of many of my rectifiers. And I think it is important to emphasize that these v-drop numbers were not lifted from datasheets. They were measured in my Glenn OTL and therefore, they are directly comparable to one another.

So looking over my list, I quickly see three rectifiers that have the exact same measured v-drop: a Mullard FW4-500, a British Tungsram FW4-500 and a Holland-made Philips AZ50. In each case the v-drop was 35 volts and B+ was 222 volts. According to theory, these rectifiers should sound identical. The operating points for all the other tubes in the amp are the same regardless of which rectifier is used.

However, they do not sound the same. They are not even similar. And I will thank you in advance if you do not insult me and assert that "you hear what you expect to hear. Much of this is mental." Again, they sound significantly different. Further, I find it very interesting that each of these rectifiers sound similar to double triodes manufactured by the same maker.

Taking this to the next step, rectifiers manufactured by Mullard all sound quite similar regardless of their measured voltage drop. And the same can be said for Telefunken, Valvo and other makers. My conclusion is the factory of origin, and not voltage drop, is a much more reliable indicator of a rectifier's sound.

To those who assert that no audio signal flows through a rectifier tube I would ask if you think 50 or 60 hertz is an audio signal? Yes indeed, an audio signal of 50 or 60 hertz is applied to the cathode of a rectifier and the output is a pulsating DC current with lots of upper harmonics. And while the power supply filters do a very good job of smoothing out the ripple and eliminating hum it would appear that enough of the upper harmonics pass through these filters to allow the rectifier's "sound" to be heard.

But hey, no one has to take my word for any of this. Anyone can gather a bunch of rectifiers, measure v-drop and test this theory. All I can say for sure is that the v-drop theory does nothing to help me understand the "sound" of rectifiers as I hear them. So I don't buy it...

Cheers

 

[UntilThen]

If I didn't venture into the use of tube rectifiers, I too would believe this theory that all a rectifier does is convert AC to DC...... BUT...... I have use GEC U52, Cossor 53ku and Mullard GZ34 in my Studio Six and I can tell you that the change in tone is more than what a voltage drop does. Sceptics should hear it for themselves before calling you mental. This is pure rudeness and I know who that is coming from. The same dude who goes around calling others noobs and boys.

So let it be known... I hear what you hear Ken. The difference in tone from a change of rectifiers is more than subtle. It's musical !

 

[UntilThen]

This thread used to be a friendly, courteous and polite thread. All it takes is one bad potato to spoil it.

 

[L0rdGwyn]

I hope I am not a potato.

 

[Monsterzero]

@Monsterzero Toshiba are the most airy and are fastest to my ears. Slightly brighter than the Fivre and RCA. I think the Fivre have the best mids and body. The RCAs though are great all-rounders, surprisingly similar to the Fivre and way more available.

Based on what I have heard you say about the VO, I think the Toshibas would be up your alley. If you want them though, you gotta buy them from Japan. Those Japanese auction-goers know these are good tubes, usually multiple bidders and a full set would cost you around $150 USD. Maybe they are using them for guitar amps? I don't know, but they are desirable.

Thanks for that. IIRC you had a resource for an online shop that was swimming in 6BX7s. Can you kindly repost that URL?

Too many 6BX7s are GE rebrands,and I know about the sandblasting thing,but frankly I cant tell them apart. I feel more comfortable buying from a trusted seller who can tell me for sure what brand of 6BX7s im getting.

I also suspect this seller wont have any Fivre or Toshibas laying around,but perhaps Sylvanias or other brands? I already have 6 GEs. 2 of which say RCA,and another says Tung Sol.

 

[UntilThen]

I hope I am not a potato.

I don't believe you are the one to call G mental, so you're not a potato.

 

[Monsterzero]

I don't believe you are the one to call G mental, so you're not a potato.

I feel like a potato. Does that count?

 

[L0rdGwyn]

I don't believe you are the one to call G mental, so you're not a potato.

Well that's good. I have enough existential crises to manage without having to worry about being a spud. I have not seen anyone be that uncivilized, to gibosi or others, but maybe I was off tube rolling...

Thanks for that. IIRC you had a resource for an online shop that was swimming in 6BX7s. Can you kindly repost that URL?

Too many 6BX7s are GE rebrands,and I know about the sandblasting thing,but frankly I cant tell them apart. I feel more comfortable buying from a trusted seller who can tell me for sure what brand of 6BX7s im getting.

I also suspect this seller wont have any Fivre or Toshibas laying around,but perhaps Sylvanias or other brands? I already have 6 GEs. 2 of which say RCA,and another says Tung Sol.

The guy who has a ton of 6BX7s is Jim Cross at Vacuumtubes.net. Just have to reach out to him. I will PM you with more info on Toshibas.

 

[UntilThen]

One more post before I take a break from here for a long time.

This is the glue I found out yesterday that works really well with loose tube base. It's liquid and easily applied with no mess. Dries in seconds.

 

[heliosphann]

What's wrong with Taylor Swift?!?!

Nothing. Especially this:

 

[heliosphann]

I hope I am not a potato.

Hopefully at least fried.

One more post before I take a break from here for a long time.

Thank the Gods! My prayers have been answered.

 

[rnros]

For those who have some interest in tube rectifiers.....

A number of folks in this forum subscribe to the theory that rectifiers have no sound. They believe that any and all sonic changes resulting from rolling rectifiers is due to a change in voltage drop, which changes B+, which alters the operating points of the other tubes in the circuit. Again this is a theory. Some people believe it and others don't. And I have seen nothing in writing which attempts to prove or disprove this theory.

In the end, from my perspective, if a theory is useful and helps me understand the "sound" of rectifiers, it is a good theory. And if it doesn't fit reality as I experience it, it's a lousy theory and I dismiss it.

Fortunately, it is very easy to test this theory. All that is necessary is decent sized collection of rectifiers and a volt meter and it just so happens that I have both of these. A couple years ago, I measured the voltage drop of many of my rectifiers. And I think it is important to emphasize that these v-drop numbers were not lifted from datasheets. They were measured in my Glenn OTL and therefore, they are directly comparable to one another.

So looking over my list, I quickly see three rectifiers that have the exact same measured v-drop: a Mullard FW4-500, a British Tungsram FW4-500 and a Holland-made Philips AZ50. In each case the v-drop was 35 volts and B+ was 222 volts. According to theory, these rectifiers should sound identical. The operating points for all the other tubes in the amp are the same regardless of which rectifier is used.

However, they do not sound the same. They are not even similar. And I will thank you in advance if you do not insult me and assert that "you hear what you expect to hear. Much of this is mental." Again, they sound significantly different. Further, I find it very interesting that each of these rectifiers sound similar to double triodes manufactured by the same maker.

Taking this to the next step, rectifiers manufactured by Mullard all sound quite similar regardless of their measured voltage drop. And the same can be said for Telefunken, Valvo and other makers. My conclusion is the factory of origin, and not voltage drop, is a much more reliable indicator of a rectifier's sound.

To those who assert that no audio signal flows through a rectifier tube I would ask if you think 50 or 60 hertz is an audio signal? Yes indeed, an audio signal of 50 or 60 hertz is applied to the cathode of a rectifier and the output is a pulsating DC current with lots of upper harmonics. And while the power supply filters do a very good job of smoothing out the ripple and eliminating hum it would appear that enough of the upper harmonics pass through these filters to allow the rectifier's "sound" to be heard.

But hey, no one has to take my word for any of this. Anyone can gather a bunch of rectifiers, measure v-drop and test this theory. All I can say for sure is that the v-drop theory does nothing to help me understand the "sound" of rectifiers as I hear them. So I don't buy it...

Cheers

Bravo @gibosi, first theoretical offering I've heard that comes closer to reality. At least the reality that some of us experience.
Have to applaud you for your clarity of thought and diligent work.

Also for daring to go where few would go. LOL, I have heard stories that in darker times, people were burned alive in the public square for suggesting that the Earth orbited around the Sun, or the Earth was round, or rectifier tubes had their own unique sound. I know, hard to believe, but it's true. Well, maybe not for rectifier heresy, we know rectifier tubes did not exist at that time...
But in fact, and ironically, the people doing the burning were called 'The Rectifiers.'

The Scientific Method is alive and well, the inquiry is open and active, the Unified Rectifier Theory is within reach.

Seriously, gibosi, thanks. Well done. Appreciate this information and all the tube information you continuously contribute to the thread.