Do you need to match pre amp tubes?

Do you need to match pre amp tubes?

Pre-amp tubes do not need to be matched, you can get a dual triode (12AX7, 12AT7 etc.) with “matched” or “balanced” triodes but that only comes into play if you’re using it as a phase inverter and even then, the jury is still out on whether it’s beneficial or not.

How tall is a Tung Sol 7591 vacuum tube?

Asked by Anonymous on February 1st, 2019. This tube measures 2.87″ tall not including the pins while the JJ 7591 measures 3.11″ tall excluding the pins. This tube is shorter than the JJ 7591. 1 answers Will the Tung-Sol 7591A fit height-wise in my Scott 380 Receiver with the overhead screen in the wooden cabinet?

What does it mean when a power tube is a matched set?

Most power tubes are sold as a matched set (duet, quad, etc). It would be hard get them from most places other than like this. I can’t explain what it is exactly (the experts will let us know) but it keeps amps quieter for one thing. You can get “matched” preamp tubes for tubes like a 12AX7. This has benefits if it is used in a phase inverter.

Can you match power tubes on a tube tester?

You cannot effectively match power tubes on a typical tube tester. Tube testers never applied the amount of voltage necessary to get accurate measurements of power tubes. In fact, there are only a couple very rare models that will allow you to get close to the voltages needed and allow you to read the parameters correctly.

Where did the RCA 7591A tube come from?

RCA-7591A – “RCA” Coin-base, low-hours matched pair of known NOS origin. These were purchased new by Dave in the old days. 7591GM – “GM” Rebased NOS matched pair of 6GM5’s.

Is the 7591 output tube the same as the 6gm5?

While the 7591 output tube is becoming more scarce and expensive, it is actually one of a family of three tubes with essentially identical characteristics. The three tubes are the 7591, 7868, and 6GM5. Ratings are identical, and the only electrical differences are very, very minor differences in interelectrode capacitances.

Is the 7591s tube better than the eh?

Unfortunately, the JJ-brand 7591S tubes didn’t fare well in the new test. Their original weaker performance became still weaker with the additional bias current, delivering only an average of 63% of the power that NOS tubes deliver. You might be tempted at this point to dismiss the JJ’s as a weak contender, next to the EH’s.

What’s the difference between the 7591 and 7868 vacuum tubes?

Ratings are identical, and the only electrical differences are very, very minor differences in interelectrode capacitances. The 7591 has an octal base, the 7868 has a 9 pin Novar base (9 pin compactron), and the 6GM5 has a 9 pin miniature base (technically a Neonoval base, since it has a 9 pin miniature configuration on a larger glass bulb).