another copy?

[gyraf]

..google translate in phone-camera mode is the only way to access these, as they're image scans. Had them forever trying to get them translated, I've even posted them here on a couple of occasions, hoping for a passer-by-japanese

Some mention of background for the peltier cooling e.g. on p_03

/Jakob E.

 

[RuudNL]

If cooling of the tube was such a step forward, why haven't other manufaturers of tube microphones followed this idea?
Personally I have my doubts. I think it is a marketing gimmick.

 

[L091c]

..google translate in phone-camera mode is the only way to access these, as they're image scans. Had them forever trying to get them translated, I've even posted them here on a couple of occasions, hoping for a passer-by-japanese

Some mention of background for the peltier cooling e.g. on p_03

/Jakob E.

Ok I'll give it a go (learning Japanese), my wife is back from Japan next month so she can correct my mistakes.

 

[TLRT]

I serviced recently a C800G and measured the tube without cooler goes up to 45-50celsius max(with FLIR thermo camera). The bigger flaws are in the PSU, the peltier element is consuming more than the mic itself and some parts are underdesigned.

 

[gyraf]

imo the biggest flaw is that peltier over-cools, attracts condensation, corrodes by its edges, and thus short the heater voltage.. seen this twice

/Jakob E.

 

[mjrippe]

I serviced recently a C800G and measured the tube without cooler goes up to 45-50celsius max(with FLIR thermo camera). The bigger flaws are in the PSU, the peltier element is consuming more than the mic itself and some parts are underdesigned.

But did you measure THD with and without, or headroom?

 

[Script]

Just a quick glance at p 3 of Gyraf's scans, they mention use of heat pipe indeed, suggesting it's something of a technological update from a 1940s design to a 1990s design. Could also try take a closer look.

 

[Script]

Read on a bit more. Without understanding everything in full detail, it looks like a cost-performance decision. Said Peltier allowed them to run the tubes cooler resulting in 1.5dB lower noise floor/ lower second/ lower third and thus getting closer (flatter bass, clearer high) to what they were already using but, if I understand correctly, had aged and was to expensive to maintain (low-noise Telefunken).

Does that make sense ?

 

[mhelin]

They used 1mA (230mW) for biasing the capsule alone, too. Couldn't the peltier be replaced with a bare passive, maybe improved, heat pipe (which it already uses) for an example?

 

[JohnRoberts]

Just a quick glance at p 3 of Gyraf's scans, they mention use of heat pipe indeed, suggesting it's something of a technological update from a 1940s design to a 1990s design. Could also try take a closer look.

a heat pipe as the name sounds exhibits low thermal resistance to more effectively move heat from a hot heat source to a cooler heat sink to dissipate that heat.

Read on a bit more. Without understanding everything in full detail, it looks like a cost-performance decision. Said Peltier allowed them to run the tubes cooler resulting in 1.5dB lower noise floor/ lower second/ lower third and thus getting closer (flatter bass, clearer high) to what they were already using but, if I understand correctly, had aged and was to expensive to maintain (low-noise Telefunken).

Does that make sense ?

Peltier is an active heat transfer technology where the Peltier junction "pumps" heat from one side of the Peltier junction to the other. The Peltier device consumes power to operate so adds heat into the system in the process of moving it. The Peltier device does not have a very high max operating temperature before becoming mechanically unstable, so IMO is questionable for such an application, but that doesn't mean someone didn't design one. It sure sounds sexy.

Do they mention "Peltier" by name in the text?

JR

PS: Temperature is a term in noise analysis of resistors and active devices for low noise design. The temperature used for such analysis is in degrees Kelvin wrt absolute zero. To realize significant noise benefit one needs a huge temperature drop. I abandoned trying to cool mic preamps for noise benefit several decades ago as impractical. Caveat, I am not the tube guy here so I don't know what they have actually accomplished, or not.

 

[Script]

Nowhere does the article say that their design is a technological improvement or in anyway 'superior' to anything else -- which would be a very non-Japanese thing to say in the very first place (including if true) -- except best within the confines of what they chased in their own approach.

Read today first two pages (the background) where it says that
- old ribbons were getting rare and started to fail (only some 3,000 left worldwide)
- tubes and old ribbons had very good image
- wake of digital recording
- national broadcaster, recording industry, studios, producers and even musicians kept asking for those ribbons (image and analog sound)
- praise of Sony for it cos generally known / image as a leader in digital
- studios in US and UK were gradually turning digital

Then comes an interesting sentence (p 149, left column, last para):

"Today there are only 5,000 original ribbon Sphere mics left worldwide. These are failing one by one. Simply exchanging the tubes does not recover them, those mics are in [gradually] deteriorating shape. Since in Japan, broadcasting equipment used by NHK [national broadcaster, monopoly] finds its way into the entire world, those [originally used] aging ribbons ones, for lack of reference and even if they display lowered/deteriorated sound quality, are sure associated with the sound of [a proper] ribbon Sphere mic " -- [So here we have the marketing decision].

Then it continues [paraphrased] to insinuate possible areas of use/demand. Mentions that their approach was not driven by digital-versus-analog as such, that there are people who can hear whether it sounds good or bad, and concludes that, although tubes are not needed from a purely operational point of view, that the idea was to offer that 'analog' / 'natural' sound of tube ribbons. sphere mics.

-------
My conclusion:
They were chasing a sound they were about to lose, could build on a strong image (=demand) and had the monopoly of NHK as an almost guaranteed sales channel partner.

(Need coffee now. Might look into technical details some other time.)

 

[Script]

Do they mention "Peltier" by name in the text?

Yes.
Scan 3, p. 150, in schematic in reads "Peltier element"

In text it says, in Japanese, 'heato pipu', and picture on opposite side, although no legend, I'd guess shows the thing.

Tubes running at 70/80 degrees typically. Element cools glass surface of tube down by 35, resulting in 10 less [overall ? internally ?] -- it says somewhere.

 

[JohnRoberts]

I am not knowledgeable about noise behavior in tubes but for Johnson noise in resistors its the temperature relative to absolute zero (-273'C). Cooling a resistor 35'C is not significant on that scale. It must be significant for tubes or why go to that much trouble?

JR

 

[mjrippe]

I am a bit confused by the interchange of "tube" and "ribbon" above. I am guessing that the 5000 remaining mics are ribbon mics made in Japan, not worldwide. But I do not know of any vintage ribbon mic that also had a tube inside. Yes, tubes were getting harder to find, but ribbons can always be made. I'm sure something is being lost in translation here

 

[Script]

Sphere type microphone C-37A ? Maybe ? - Cherished for it's ribbon-like character bla...

Yeah, sphere microphone. Edited above. Don't know much about mics -- just happen to know some Japanese... and those damn kanjis all look the same

 

[mjrippe]

Sphere type microphone C-37A ? Maybe ? - Cherished for it's ribbon-like character bla...

Yeah, sphere microphone. Edited above. Don't know much about mics -- just happen to know some Japanese... and those damn kanjis all look the same

Haha, I appreciate your efforts!

 

[Gus]

HV and UHV is interesting
Atoms stick to the cooler surfaces more and longer than the hot surfaces

The 6AU6 is run at a higher plate current.
If you look at the curves you might figure out why. This is part of the sound.

Grids in tube are often speced at 1meg max grid resistance.
This is not done with most tube microphones.

Yes the microphone costs a good deal of money.

So why not go over the top with noise reduction.

What the clones seem to miss is the capsule/grill environment that is more important than other parts of the microphone IMO.

I am not posting this as a C800G fan.

If I was to build a microphone something like a C800G keeping the cooling I would rearrange the physical location of the tube and heatpipe and also make sure it has a drip hole and/or some kind of material to wick the moisture that leads the condensation away from the connectors.

I have built an add on circuit for a 6AU6 run at this this plate current so you don't need the cooling and the tube should have a longer service life

Instead of posting negative responses why not learn somethings.

Sometimes this place sounds like old guys sitting at a bar drinking talking about how to fix (fill in the blank).

 

[mjrippe]

HV and UHV is interesting
Atoms stick to the cooler surfaces more and longer than the hot surfaces

The 6AU6 is run at a higher plate current.
If you look at the curves you might figure out why. This is part of the sound.

Grids in tube are often speced at 1meg max grid resistance.
This is not done with most tube microphones.

Yes the microphone costs a good deal of money.

So why not go over the top with noise reduction.

What the clones seem to miss is the capsule/grill environment that is more important than other parts of the microphone IMO.

I am not posting this as a C800G fan.

If I was to build a microphone something like a C800G keeping the cooling I would rearrange the physical location of the tube and heatpipe and also make sure it has a drip hole and/or some kind of material to wick the moisture that leads the condensation away from the connectors.

I have built an add on circuit for a 6AU6 run at this this plate current so you don't need the cooling and the tube should have a longer service life

Instead of posting negative responses why not learn somethings.

Sometimes this place sounds like old guys sitting at a bar drinking talking about how to fix (fill in the blank).

Not trying to pick on you Gus, but once again you are saying that the high price means it must be better. Once again, I call BS.

I am absolutely interested in learning, but part of that is questioning things. I simply want to know if anyone (besides Sony) has done the most basic of testing. Apparently not.

If anyone here has a C800G I am extending an invitation to put this matter to rest. I have access to an anechoic chamber and an Audio Precision 555. Bring or send your mic here and we can do a test with and without cooling and get actual measurements.

Mike Rippe
Brooklyn, NY

 

[L091c]

If I was to build a microphone something like a C800G keeping the cooling I would rearrange the physical location of the tube and heatpipe

The article says they put the tube and Peltier at the back for aesthetic reasons (the singer would notice it less it says). They also say they addressed the condensation (but we were informed here that it is still corroding)

 

[kingkorg]

The capsule within.