Which tube spots for which affects?

Here's something I've now been pondering about tube sets in preamps.  Which positions in them are more likely to have what affect on the sound  when rolling?  For example my new-ish Raven Blackhawk has 3 pairs in the pre amp section that are noted as Preamp, Power amplifier first stage, Phase inverter/driver.  Is one set more or less likely than the others to affect say, warmth or another pair dynamics?  Which the sound stage?  Are some locations better for a "euphonic" tube or a very accurate set?  I'm sure it's really the sum of ALL the parts but maybe they each have their particular impacts.  Hearing differences but wondering if there's a pattern/ causal/predictability to it all.  I don't expect there's a single answer but maybe enough anecdotal evidence and experience might show a trend.  


noted as Preamp, Power amplifier first stage, Phase inverter/driver.  Is one set more or less likely than the others to affect say, warmth or another pair dynamics?

For instance my pre has no inverter/driver stage. And really only one tube/channel.

More may not be better.

The preamp tubes will have the most significant effect on sonic signature. The power amp 1st stage (the gain stage) will also have a noticeable effect on sonics. Phase inverter/driver will affect sound to a certain extent depending on the design of the amp.

Attributes of the sound such as warmth, dynamics, soundstage depend on the manufacturer of a tube and the tube type. The tubes you asked about are all input tubes, as opposed to the larger output tubes. BTW, we refer to changing the tubes as "rolling tubes."


Brent Jessee has a very good description of how different tubes sound. Click on the tube type that your amp uses.



i had a blackhawk and loved it.  all three small tubes matter.  beg, borrow or steal 2 amperex bugle boy 12AT7 for the preamp tubes.  amazingly open, transparent and dynamic.  

i also used rca 12AU7 5963 black plates in the back row and sylvania 12AT7 jan triple mica for the front row. 

the rca and sylvania are cheap but excellent, the amperex are not but well worth it.

It depends the amp, but preamp tubes and amp input/gain tubes (V1) will usually have big overall impact, especially on tone and air. The preamp slot is also going to be the most sensitive to noise and microphony, by far - so careful selection here matters.

The drivers can have a big impact on dynamics, especially if you have a couple small crappy tubes like 12au7 driving a lot of big KT tubes. In my VAC 200iQ’s I found that Russian Tung Sol 6SN7GTB are the best driver / V2 tubes by far - not because they’re the best sounding tubes (they’re not) but because they’re the strongest tubes, stronger than any NOS you’ll likely find. They don’t stain at all driving the KT tubes. In V1 slots however, the old vintage USA tubes are killing it - way better tone and air versus the Russians in those slots.

The phase splitter can mean different things to different circuits, as far as its impact to tube rolling goes. Experiment and learn!

This is hard to generalize since each system responds differently towards tube rolling.  I am a Raven Blackhawk owner and have found the row one seems to respond the most and row 3 the least to tube changes.  In my system I have found that Row 1 impacts clarity, dynamics, detail.  Row 2 soundstage, overall sound warmth/brightness Row 3 overall tone and some dynamics, seems to impact feeling for a lack of better words.  

Below is a past posting on a prior Raven thread….

If you want absolute sonic bliss get an old stock quad of RCA  6L6GC black plates.  Raven Dave’s  Shuguang 6L6GC coke bottle sound really nice but the RCA’s wow!  Dave offers an amazing choice of fantastic tubes that he can get quantities on but their are some really nice ones he just can’t get to offer the Raven family.  After quite a bit of rolling these are the tubes that work well with my Blackhawk  in my system.
6L6GC output tubes:  1- RCA black plate 50’s- 60’s bottom getter, 2- Shuguang 60’s coke bottle 3- Svetlana original winged C’s
Row 1:  Detailed Dynamic tube 1- Tungsram 70’s with silver square getter supports,  2- Matsushita 60’s-70’s with 45 degree angled getter, 3- Telefunken early 50’s made
Row 2: Warm full sounding midrange tube 1- Mullard 50’s square getter with 3 plate holes... another wow 2- Brimar 13D9 (Note: I don’t own Brimar 6006 yellow T’s)
3- Amperex ‘50’s foil getter
Row 3: Warmer full soundstage tube 1- Westinghouse 60’s  Long Carbon Plate square getter on copper post 2- Rca 50’s-60’s 5963 (or 12au7) long black plates and 5814A 50’s triple mica black plate, 3- Raytheon 5814A (12au7) black plate, triple mica with square getter.  

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Lots of good knowledge and experience here.  Thanks.  When I ordered mine I opted for a slight upgrade in the preamp, to NOS GEs.  In the power pre-stage I took their advice to go better for some Brimar NOS tubes.  They didn't put too much stock in the inverter stage.  I explained I ready had some very nice NOS 12AU7 Mazda tubes I got through Brent Jesse from another piece.  Out of the box it was lights out better than what i was coming from.  4 months later i was wondering how much better was possible so I asked Brent for a recommendation for the preamp row 1 12AT7 spots.  I opted for some instrument grade RCA gray plates.   The difference was audible in the staging.  It was wide, discrete before but now it also seems deep.  Eerie.  Anyway I went back and rolled another, less pricey pair of 12Au7 in the inverter (JJ gold) but I couldn't hear much change.  So yes, inverter row 3 seems less critical and 1 is for sure.  With my extra sets and ability to swap rows one and two (both 12AT7), I have 24 possible combos.  So I am trying to eliminate or focus on a few likely ones.  Thanks for the tips all.  Lots to digest for a new roller.    

Everything is important to the sound.

It would make a cute jingle if it were true.

In most preamps the first gain stage is the most important. although I hear differences in just about every section including the rectifiers. I think this really depends on the circuit but I usually tell my clients to spend the most on the first or most significant section. This information can be had from the mfgr. In most tube amps I have heard a greater difference in the driver tubes than the power tubes. Avoid enthusiasts that claim something cant make a difference based on theory and not actual practise.