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Ruben1
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6ER5 Tube in preamps Question

I am a recent convert to tubes (about 3 years) and have purchased a tube line stage and power amp, and have done a great deal of reading on the subject but I only recently came across this tube when reading about the Wright Sounds WPP 100 phono stage. this unit uses 4 of these tubes along with 2 12AU7's.

In all the searches I have done for tube gear and in all the reading I have done I did not come across a unit using the 6ER5 tube except for the Wright Sounds unit.

What is the benefit or shortcoming of this tube that it is not widely used at all (my perception) compared to the more common 6DJ8, 6SN7, 12AX7, etc, etc in preamps? It seems so odd that every other manufacturer/designer uses the more common tubes but the Wright Sound WPP100 uses this obscure one? Thank you

Jan Vigne
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Re: 6ER5 Tube in preamps Question

Why a particular tube is selected as OEM equipment by any manufacturer is probably a question only that manufacturer can really answer. Tubes are often selected with a ranking of priorities by the manufacturer and those will vary from manufacturer to manufacturer. Realiability of the tube is very often the first consideration for a designer, any piece of equipment sounds better in your home than in a repair shop. Long term availability of replacements is important to the designer who sees the sound you purchased today as the sound you will expect in five or ten years when tube replacement becomes an issue. Low microphonics or individual specs which would indicate a proper placement within a circuit would enter into the picture. A very low noise tube or one with extended frequency response would be desirable in a phono pre amp but more likely a waste of money in a line input. Possibly, when a manufacturer selects a specific tube well out of the ordinary they are looking at the construction of the tube and seeking something other than the standard dual triode layout. Sound quality can sometimes be a fourth or fifth consideration.

The tube you name was meant for other than audio useage - if I read it correctly, it is a receiving tube in a television. This going outside of the audio norm has not been an uncommon selection in tube pre amps for decades. The 6DJ8/6922/ECC88 was the first tube I'm aware of which sought a sound unlike the typical and more ubiquitous 12AX7. As long as the manufacturer feels they are reliable tubes with specs which meet their design needs and that they can be found in sufficient quantities to make replacement a simple task, then that is reason enough for some designers to implement an out of the ordinary tube choice.

That may not answer your question but any further, more specific information reagrding tube selection would, I think, have to come from the manufacturer of your pre amp.

Ruben1
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Re: 6ER5 Tube in preamps Question

Thank you Jan for the prompt reply. Unfortunately it does not answer my question and even more unfortunate for the audio industry is the fact that George Wright passed away last year and he was the entire company so he is not available to be asked about this.

Again, this is of great curiosity to me that someone (George) found this particular tube to do what he wanted out of a tube in a phono stage but the rest of the audio industry (maybe not all the rest but the ones I know) have completely ignored it for some reason. just trying to understand (speculate) why this would be the case?

Jan Vigne
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Re: 6ER5 Tube in preamps Question

So what do you do if the unit ever requires servicing?

Jim Tavegia
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Re: 6ER5 Tube in preamps Question
Jan Vigne
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Re: 6ER5 Tube in preamps Question

If that was meant as a reply to my question about servicing, yeah, we can buy new tubes. That's not an issue with most audio tubes. My question goes to who will do the servicing of the equipment. It's quite possible an experienced service technician will have some insight into why a particular tube was selected and they quite possibly have been told why not to substitute a different tube in its place.

Ruben1
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Re: 6ER5 Tube in preamps Question

To clarify....I did not state that I own this unit but rather that I want to learn/have an insight as to why this particular tube might have been used by this audio designer when no other designer/manufacturer seems to have done so. It is a significant curiosity that I have as an avid audio enthusiast.

let me ask the question differently....Is there anyone on this forum whom might have spoken with George Wright regarding this phono stage and has an insight as to why this particular tube was used?

Opinions and guesses are also welcomed. Thank you

SAS Audio
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Re: 6ER5 Tube in preamps Question


Quote:
To clarify....I did not state that I own this unit but rather that I want to learn/have an insight as to why this particular tube might have been used by this audio designer when no other designer/manufacturer seems to have done so. It is a significant curiosity that I have as an avid audio enthusiast.

let me ask the question differently....Is there anyone on this forum whom might have spoken with George Wright regarding this phono stage and has an insight as to why this particular tube was used?

Opinions and guesses are also welcomed. Thank you

Any tube can be used in audio. It is a matter of specs etc.

1) The 6ER5 has a mu between a 12AT7 and 12Ax7. So high gain.

2) The tube has twice the transconductance of a 12AT7, and much greater than that of a 12AX7. The plate resistance is lower than either, so the noise figure should be lower than that of a either tube, but higher than a 6dj8.

3) The grid to plate capacitance is very low, approximately .35pf. This is important when calculating the "miller capacitance", which influences the high frequency response.

4) Microphonics, hum etc are probably good.

5) Harmonic and IM distortion should be low, but I have not measured such.

Any tube can be used in audio if the factors above are considered. It is the factors above plus that influences what tube one uses.

Cheers.

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