M U 6900 (Bendix type) 5687 7044 substitute vacuum tube Utracer tested
Listing ID: lisa41jb Classified
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Listed · 467 Views
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| Condition | |
| Payment methods |       |
| Ships from | Los Angeles, CA, 90026 |
| Ships to | United States |
| Package dimensions | 10.0" × 6.0" × 2.0" (1.0 lbs.) |
| Shipping carrier | USPS |
| Shipping cost | Free |
 Average | Research Pricing |
NOS pair of M U 6900 (Bendix Red Bank style) dual triodes, substitutes for 5687 or 7044. Tested on Utracer 3+, see attached curves.
Questions for the seller |
|---|
| I assume since you will not answer my question that the tube(s) are microphonic... Hello. I don't have a fixture for this, I've found microphonics vary greatly with circuit topology and operating conditions. The 6900 would not be my first choice at a phono front end or a microphone amplifier for example, there are tubes designed specifically for high gain and low noise and this was not. What's the circuit you're using it in? |
| They are output tubes on a ModWright Anniversary Pre Amp.
Do you find the 6900s to be noisy? I can test a set for you for noise, I have a stereo line amp that uses the 6900 at full gain (copy of audio note circuit). It’s not a good test for microphonics for a phono front end but more than adequate for testing your usage. |
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