# BHK Preamp.....Afraid to try 7308’s

**URL:** <https://forum.psaudio.com/t/bhk-preamp-afraid-to-try-7308-s/6427>\
**Category:** Audio Components\
**Created:** [July 8, 2018, 10:40pm UTC](https://forum.psaudio.com/t/bhk-preamp-afraid-to-try-7308-s/6427 "2018-07-08T22:40:37Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![owlsalum](https://avatars.discourse-cdn.com/v4/letter/o/e47c2d/32.png) [@owlsalum](https://forum.psaudio.com/u/owlsalum)\
**Post date:** [July 17, 2020, 3:22pm UTC](https://forum.psaudio.com/t/bhk-preamp-afraid-to-try-7308-s/6427/21 "2020-07-17T15:22:19Z")

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I use NOS Siemens 7308s and have written about them on the tube rolling thread. They are terrific. I value them so much I switch them in and out just to limit accumulated hours so that I can enjoy them for years to come. I would guess I have around 1000 hours accumulated so far.

Nobody can ‘convince’ you to proceed it you don’t want to. I obviously have zero hesitation. Do read about and understand the correct bias jumper position to use with 6 volt tubes. Don’t just plop them in in substitute for 12AU7s without switching the bias jumper as well.  
I purchased mine from Brent Jesse btw.

I will say this about Brent. My 7308s are the finest pair of 6 volt 6DJ8 variant tubes I have ever purchased. But I purchased a second pair advertised as NOS and Gm tested out at 60% of factory spec. Haven’t purchased from his again. Don’t blame the tube type for any issues.

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**Author:** ![kcleveland123](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/kcleveland123/32/45645_2.png) [@kcleveland123](https://forum.psaudio.com/u/kcleveland123)\
**Post date:** [July 17, 2020, 3:28pm UTC](https://forum.psaudio.com/t/bhk-preamp-afraid-to-try-7308-s/6427/22 "2020-07-17T15:28:06Z")

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I had the voltage and bias current jumpers set correctly for 6V tubes. However, I purchased mine from Upscale Audio and have since had a couple of minor issues with them. I have purchased tubes through Brent Jesse in the past and his service and parts quality are excellent. Will likely pursue next set of tubes through him.

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**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\
**Post date:** [August 5, 2020, 10:15pm UTC](https://forum.psaudio.com/t/bhk-preamp-afraid-to-try-7308-s/6427/23 "2020-08-05T22:15:14Z")

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I just swapped in a full set of Siemens 7308 into my BHK 300 and Pre. They’re breaking in now.

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