rnros
1000+ Head-Fier
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- Sep 12, 2004
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I've been really enjoying these a lot so far, great detail retrieval and dynamics in my Mjolnir 2. Now I'm wondering how they work.
The specs are not the same for the 6922 and 5670 tubes. That'ss not to say that one cant plop in a 5670 into a circuit designed for a 6922 with a pin-out adapter, and the 5670 would not get harmed because its usual operating points (plate voltage and plate current) are such that there should be no danger of damage. The only parameter that is of very minor concern is the 5670's 15% higher Heater Current consumption. (350mA vs 300mA).
I have a feeling that there is something more than just a noise suppression capacitor in the iFi adapter, because to operate the 5760 at the 6922's plate voltage of around 100V (normally 150 V for the 5670) they would be affecting the 5670's prescribed bias current.
I don't believe the increase in heater current is an issue for the MJ2. Two points: The E188CC (335mA) is used all the time in the Schiit DC heater amps without issue. Also, I believe the limitation for heater current for this amp is 425mA. At the moment I don't remember where I received this information... Email with Nick @ Schiit, Jason on Head-Fi? Quick email to Nick would get you a fast answer.
On plate voltage, several different tubes are being used with different plate voltages, but I cannot give an intelligent answer as to why/how the amp circuit compensates, or how a different plate voltage affects the tube performance, although different plate voltage curves are given in the datasheet.
If you find out anything more about the adapter being used here and internal modifications, post it here, I'm curious.
I am using this tube with just the usual adapter base for this group. (Well, that is to say, I've given it some comparison listening with some other well-known tubes.) I did not expect it to perform as well as it did. Another candidate for the HS (Holy Schiit) designation. For what this tube gives at the current price, definitely a 'Holy Schiit' tube. By the way, although this tube can be purchased for $4 plus shipping, you will also need the adapters, about $20 with shipping, so a few tubes for matching and adapters will run you $40 to $50. I think the $99 for a matched pair is a good price. No hassle, no work.
To my ear, I do prefer the WE396A above this tube, but the WE396A is about $50. However, above both of these tubes, I favor the Reflector 6N3P-E (requires the same adapter), which to me was my first Holy Schiit tube. Beautiful sound and impressive construction which can be had for $2, including shipping, if you buy a handful or more, or about $20, if you buy a matched pair. The Ultimate Holy Schiit tube!