Hi there... yes I know... that red Svet site logo has been around for ages.....all old stuff as far as I 'm concerned....but can you get anyone on the red-end to give a reply ?...........NUP. ...
In the past I got far better results from the old CCCP...was just as corrupt as the recent....but at least we knew who to get info from......All this modern company takeover flannel just doesn't work to give results.....to the consumer.
This was aired on a thread sometime last year......the problem is no-one from the manufacturers side will situp and listen to diyaudioforums......Is our standing so low ?
richj.
In the past I got far better results from the old CCCP...was just as corrupt as the recent....but at least we knew who to get info from......All this modern company takeover flannel just doesn't work to give results.....to the consumer.
This was aired on a thread sometime last year......the problem is no-one from the manufacturers side will situp and listen to diyaudioforums......Is our standing so low ?
richj.
Yeah, old thread, but I have GE 5687WB's and actually found data showing both 5687WA & WB in a GE Industrial Tube data book online. Disappointing data, but something specific instead of urban & legendary.
The 5687WA had an unsurprising description of medium-mu dual triode but the WB said low-mu. In horror, I scanned the page with my eyes and saw there was only a couple lines of typical operating conditions. The mu and gm for WB was at 120 VDC B+ and for the WA at 250 VDC. The numeric values for mu and gm we're higher for the WB than the WA, contradicting the basic description. No curves. If one looks at a 5687WA datasheet, there is data for three plate voltages, 120, 180 & 250.
There was a lower number for 'WB plate dissipation with a little footnote symbol I didn't bother to pursue. For WA I recognized the two number Pd per triode depending whether one or two triodes were in use. The WB had only a single number. The WB mu was a little higher but the gm was about double (at 120 V) that of the the WA (at 250 V). This was immediately familiar. There is slight increase in mu and the highest gm on the datasheet occurs with the lowest B+ plot and highest plate current. Like on every other 5687 datasheet, with or without suffix. I could find the WB mu (18-18.5) & gm (>11000 numbers on the WA datasheet.
So I concluded:
1) The low-mu description for WB vs medium-mu in that databook was simply a typographical error.
2) The typical operating conditions for the WB were limited to 120 VDC and for the WA, 250 VDC. Obviously not limitations. More likely an indication that WB's were tested at or selected for properties at 120 V B+.
3) The conditional Pd limit that was slightly lower for WB probably doesn't indicate it had a smaller anode, but that the lower B+ and whatever the max. cathode current rating produces a lower Pd=EI that they were careful enough to edit.
If we remember 99.9% of us use 5687's for audio applications and not the digital gate or counter applications, the datasheet differences are probably irrelevant for banishing a WB from audio use. To me, the data were clearly operating condition related. That kind of variation with other tubes as well, especially for specific conditions that aren't middle-of-the-datasheet.
Some people prefer the sound of non-suffix or WA over WB, just like people have personal preferences in other areas.
I might go back & try to read the WB Pd data qualifier again. I was using a phone and the page wouldn't rotate & I just got tired of scrolling.
The 5687WA had an unsurprising description of medium-mu dual triode but the WB said low-mu. In horror, I scanned the page with my eyes and saw there was only a couple lines of typical operating conditions. The mu and gm for WB was at 120 VDC B+ and for the WA at 250 VDC. The numeric values for mu and gm we're higher for the WB than the WA, contradicting the basic description. No curves. If one looks at a 5687WA datasheet, there is data for three plate voltages, 120, 180 & 250.
There was a lower number for 'WB plate dissipation with a little footnote symbol I didn't bother to pursue. For WA I recognized the two number Pd per triode depending whether one or two triodes were in use. The WB had only a single number. The WB mu was a little higher but the gm was about double (at 120 V) that of the the WA (at 250 V). This was immediately familiar. There is slight increase in mu and the highest gm on the datasheet occurs with the lowest B+ plot and highest plate current. Like on every other 5687 datasheet, with or without suffix. I could find the WB mu (18-18.5) & gm (>11000 numbers on the WA datasheet.
So I concluded:
1) The low-mu description for WB vs medium-mu in that databook was simply a typographical error.
2) The typical operating conditions for the WB were limited to 120 VDC and for the WA, 250 VDC. Obviously not limitations. More likely an indication that WB's were tested at or selected for properties at 120 V B+.
3) The conditional Pd limit that was slightly lower for WB probably doesn't indicate it had a smaller anode, but that the lower B+ and whatever the max. cathode current rating produces a lower Pd=EI that they were careful enough to edit.
If we remember 99.9% of us use 5687's for audio applications and not the digital gate or counter applications, the datasheet differences are probably irrelevant for banishing a WB from audio use. To me, the data were clearly operating condition related. That kind of variation with other tubes as well, especially for specific conditions that aren't middle-of-the-datasheet.
Some people prefer the sound of non-suffix or WA over WB, just like people have personal preferences in other areas.
I might go back & try to read the WB Pd data qualifier again. I was using a phone and the page wouldn't rotate & I just got tired of scrolling.
The "article" by Morgan Jones referred to above regarding the 5687 and the 5687WB is actually Table 3.13 in 'Valve Amplifiers' 4th ed. The table does not cast dispersions on all 5687WB, only the Philips version which is considerably higher in distortion in Jones' tests. The table's purpose is to compare various tube types H2, H3, & H4 distortion to a 6SN7.
Tubes of the same exact type can vary, sometimes due to varying materials, sometimes due to variation in physical tolerances, other times...???
That the Philips ECG 5687WB that Morgan Jones tested measured worse for THD than older Tung-Sol 5687 tubes does not mean they are different types. It just means that the (1980s) generation of Philips ECG 5687WB varied in those ways from the older (1960s) production of Tung-Sol 5687. Perhaps the ECG 5687WB was just plain worse, or maybe it was more stable when running in cutoff with no plate voltage (one of the original reasons for developing the 5687) but worse for audio (which it was not designed for specifically).
What the letters mean:
W = ruggedized construction
A = variation 'A' - often controlled heater warmup time for use in series heater strings, sometimes for other reasons.
B = variation 'B' - for whatever reason, sometimes higher voltage or plate dissipation ratings, other times...?
Example:
6SN7GT - original version glass envelope ("G"), straight sides ("T") - Max plate dissipation = 2.5W each, both plates operating, Vp max = 300V
6SN7GTA - 'A' version - Max plate dissipation =3.75W each, both plates operating, Vp max = 450V
6SN7GTB - 'B' version, same as 'A' but with controlled heater warmup time for use in series heater strings
6SN7WGT - ruggedized construction original version
6SN7WGTA - ruggedized construction, 'A' version
They're all 6SN7s though. All of the above show the same plate curves in their data sheets. They will vary in real life, and there may be one version that's best for your particular application, depending on what exactly that application is.
JAN = Joint Army/Navy, which only means that the tube was made under contract for military use. It does not mean the tube is better than the same thing made for civilian or industrial use (but it might).
That the Philips ECG 5687WB that Morgan Jones tested measured worse for THD than older Tung-Sol 5687 tubes does not mean they are different types. It just means that the (1980s) generation of Philips ECG 5687WB varied in those ways from the older (1960s) production of Tung-Sol 5687. Perhaps the ECG 5687WB was just plain worse, or maybe it was more stable when running in cutoff with no plate voltage (one of the original reasons for developing the 5687) but worse for audio (which it was not designed for specifically).
What the letters mean:
W = ruggedized construction
A = variation 'A' - often controlled heater warmup time for use in series heater strings, sometimes for other reasons.
B = variation 'B' - for whatever reason, sometimes higher voltage or plate dissipation ratings, other times...?
Example:
6SN7GT - original version glass envelope ("G"), straight sides ("T") - Max plate dissipation = 2.5W each, both plates operating, Vp max = 300V
6SN7GTA - 'A' version - Max plate dissipation =3.75W each, both plates operating, Vp max = 450V
6SN7GTB - 'B' version, same as 'A' but with controlled heater warmup time for use in series heater strings
6SN7WGT - ruggedized construction original version
6SN7WGTA - ruggedized construction, 'A' version
They're all 6SN7s though. All of the above show the same plate curves in their data sheets. They will vary in real life, and there may be one version that's best for your particular application, depending on what exactly that application is.
JAN = Joint Army/Navy, which only means that the tube was made under contract for military use. It does not mean the tube is better than the same thing made for civilian or industrial use (but it might).
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