# TUBES(pre, power, rectifier) share your list of tubes

**URL:** <https://forum.headphones.com/t/tubes-pre-power-rectifier-share-your-list-of-tubes/4946>\
**Category:** Miscellaneous\
**Created:** [January 20, 2020, 3:47am UTC](https://forum.headphones.com/t/tubes-pre-power-rectifier-share-your-list-of-tubes/4946 "2020-01-20T03:47:14Z")\
**Posts on this page:** 1\
**Showing post:** 89

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**Author:** ![PaisleyUnderground](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paisleyunderground/32/15919_2.png) [@PaisleyUnderground](https://forum.headphones.com/u/PaisleyUnderground)\
**Post date:** [March 12, 2021, 5:07pm UTC](https://forum.headphones.com/t/tubes-pre-power-rectifier-share-your-list-of-tubes/4946/89 "2021-03-12T17:07:51Z")

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I’m ready to put in an order with Brent Jessee for my Nautilus tubes, based on a conversation with Justin yesterday:

- **Sylvania 5751 blackplate** , as a replacement for the 12AX7. Justin raved about the sound quality of these, and said that they have lower gain than a 12AX7.

- **Mazda 12AU7**. Justin didn’t recommend this but I’m curious about how a European tube will sound, and I have 2 amps that will take this tube, so why not.

- **Tung Sol 6550 made for other companies**. These are a lot cheaper than the Tung Sol labeled “holy grail” 6550.

I’m still trying to choose between an Amperex/Miniwatt 5AR4/GZ34 or a much cheaper Tung Sol 5U4G and I had a question about the difference in sound between a 5AR4 and a 5U4G. I saw [this post](https://forum.headphones.com/t/zmf-pendant-tube-headphone-amplifier-official-thread/4791/511) just now by @bpcarb but I don’t understand what “sag” is.

If I want speed and rhythm, do I want less sag?

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