2. amps-preamps
  3. 147225-115924

Tube Rolling for Pre-amps?

I have an Audio Research LS-16 that feeds a Madrigal Proceed HPA2 solid state amp. 

I did not choose this equipment; it was given to me. From what I can tell the original owner spent a good bit of time matching up these two components with the speakers, Aerial Acoustics 7Bs.

The tubes in the AR are original. Probably 10-15 years old? But with an extended period of not being used.

The system sounds good to me. I don't need to change anything.

However, I've been told that the tubes are old and may need to be replaced soon. I've also read a little bit about tube rolling but most of the articles I've seen talk mostly about tube rolling with amps and not pre-amps.

So I have some questions:

1) If the original owner wanted a system that sounded like a 'tube' system, why not have a tube amp and pre-amp? Does it make sense to have a tube pre but SS amp?

2) Other than outright failure, how will I know if my tubes _need_ to be replaced?

3) With a SS amp, will changing tubes in the pre-amp have a noticeable impact on SQ? In other words, is tube rolling for a pre-amp played through a SS amp a thing?

4) For someone like myself who is happy with the system and who is also easily frustrated by A/B testing is tube rolling the pre-amp even worthwhile? I can almost always hear a change when comparing various components but only rarely am able to say A is better or worse than B.

( I probably can't even articulate effectively what I look for in terms of SQ except that I like the bass to be tight, precise, well defined and not boomy. I do not like the music to be overly bright or tinny. I like depth and lushness but not overly warm. Not sure if these are things you alter with tubes.)

Thanks for any advice.


n80
lowrider57's avatar
lowrider57
5,418 posts
 
You should have a spare set of tubes as I and others have stated. I like the idea of comparing the new pair with yours, then use the tubes that sound best.

Even though your preamp may have sat idle for a long period, the former owner may have put a lot of hours on his system. Or he could have left the preamp powered up for long periods of time.

n80 OP
2,133 posts
 
I do have the MKI which means 4 tubes to replace or try rather than 2.

@rodman99999 : "There’s no problem, trying just one pair per gain stage, at a time, to see if you like the change."

I’m not sure what that means. Does that mean I can just change 2 of the 4 tubes to get an adequate test of SQ?

"NOS Siemens(tighter bottom, airier and more detailed/cleaner than stock)."

That sounds like what I would want. A search reveals that gold pin versions of those tubes go for around $40 - $75 each. Does that sound right? How careful do I need to be to avoid fakes or crappy tubes?

" IF you’re actually happy with your sound, why fix something that isn’t broken? Just don’t go listening to a lot of live music."

I am actually quite happy with the sound, but there’s always that audiophile neurosis that whispers in my ear that maybe it could be better and I just don’t know how bad it sounds right now. But I don’t understand what you mean about live music. Live music recordings? I only have a few, all on vinyl. Not all that crazy about live recordings, but why would live recordings be a problem?

Edit: At Upscale Audio those Siemens tubes are $135 each and their site says they do not sell NOS. Does that mean they are used? How do you know how many hours are on them? Well, its all academic since right now there is no way I'm spending $500+ on a set of tubes. (I realize that's chump change for serious tube rollers).
lowrider57's avatar
lowrider57
5,418 posts
 
n80, you have no baseline or reference to judge the SQ of your preamp.

That’s a good description of Siemens. Where are you looking for tubes and which tube type is $40-70 each? There are 6DJ8, 6922, and 7DJ8 variants.
Check Brent Jessee’s selection. Trustworthy seller with good pricing.


n80 OP
2,133 posts
 
@lowrider57  : " n80, you have no baseline or reference to judge the SQ of your preamp."

That's what I'm saying. It is a blessing and a curse! The blessing is that I think it sounds great. The curse is that it might not. ;-)

I don't remember where those prices came from. Just a Google search. I don't know anything about types. This is what comes in the pre-amp:   6922/E88CC dual triode. It takes 4.
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