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... How to select tubes for line level preamp ...

Hi to all...

Kinda happy with the sound of my present system: older Marantz SA-8001 SACD, into Wolze Line Level preamp with 2- EF86s and 2-12AX7 tubes, and pre-out to a discoed Yamaha HTA-5550, into a pair of KEF Q1s. The sound is really nice )
amazing midrange ( would be happier if the center/vocals were pushed more forward), adequate bass and thumping drums - but the upper sparkle (cymbals and other higher pitched sounds) just don’t sparkle in comparison (or like I think they should).

How do I keep everything I really like and expand what I want to find? Is there a chart or reference guide to tube characteristics? Sounds like strict experimenting is an expensive guessing game...

Help? Suggestions?

insearchofprat
insearchofprat OP
189 posts
 
DeKay

Did you /do you have one of these - it’s been "rumored" there was less than 10 ever available: any opinion /review from your memory?

If you can explain please what is the differrence between a 12au7 and
a 12ax7 (other than having this one Wolze piece - I have no reference to tubes what so ever).

Thanks...
dekay's avatar
dekay
5,387 posts
 
The 12ax7 has approx. 5 times the gain of a 12au7 "type" tube. 

Never seen/heard you preamp but, from what I recall about it an unusual 12au7 type was used.

I may have run  across the Wolze when researching tubes for my "early" Bottlehead Foreplay 12au7 based preamp years ago, but I do not recall the specifics (certain that it was not a 12ax7 though).

I'll try searching the old Bottlehead forums tomorrow to see if I can come up with the 12au7 equivalent that I researched (like 15 years ago;-)

This said, if it has been changed/modded this will be a mute point.

I've rolled the 86 tubes in something (thinking a vintage Pilot 690 preamp/tuner), but again I do not recall specifics as this was a long time ago.

Anyway, if it does end up using a 12au7 I'm familiar with gobs of old production types and can chime in @ that point.

DeKay  

insearchofprat OP
189 posts
 
DeKay

Thanks for the courtesy of your reply... 
mijostyn's avatar
mijostyn
8,231 posts
 
insearchof, The most important characteristic of a tube is noise. There is a lot of variability between tubes even of the same manufacturer. Noisier tubes decrease dynamic range and can interfere with quiet passages.
RAM Labs tests their tubes individually and rates them as standard, low noise and super low noise. They are priced accordingly. I use their SLN tubes in my ARC phono amp and they are an easy 10 dB quieter than the tubes that came with the unit.  http://www.tubeaudiostore.com/
dekay's avatar
dekay
5,387 posts
 
Couldn't come up with much other than a few references to 12au7 and 6211 tubes in the Wolze (along with EF86).

These came from title headings on Google, but the articles/pages were no longer available.

6211 must have been the tube I researched for the BH preamp.

Some hits to VTV magazine that I did not look at (reading VTV gives me a headache).

I understand that these were kits so anything is possible considering Wolze and the wild and crazy guys/people who most likely built them.

What 12ax7's are you currently using?

DeKay
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