I’ve put just about every respected variant of a 12au7 and 6922 in my preamp. I’ve bought, listened to and flipped a lot of tubes. And I’ve owned a pair of Amperex 7308’s in that lot. The best tube I’ve found so far is a fairly rare Haltron Harlen Holland Tunsgram 12AU7. It has green writing and a welded disc getter. Quite expensive but the bass, midrange and treble is prefect. And the imaging depth is vast. Not cheap though.
So can anyone actually give me some engineering based reason to not use the Lisst tubes?
I’ve got about 800 hours of listening pleasure from a pair of Amperex 7308. I just switched to Brimar CV4003/12AU7 because I bought them months ago and haven’t tried them.
NIce, especially with female vocals. A touch brighter in the upper midrange and a bit bloated in the bass compared to the Amperex, but the brightness calms down some as they reach temp and /or I get used to it. Unfortunately, one of them pulses. I can’t hear it from more than 3’ away but the other doesn’t do it.
For grins, I switched back to a set of stock Psvanes. Wow, how un-engaging they make the sound. Yuck.
I have found the Preamp isn’t as friendly as the amps to roll tubes. I’ve had a bunch of tubes that start to pulse only they get warmed up a while. Odd thing, it’s always the right side too?? PSA had even swapped my preamp main board a while back. Sorta a bummer.
Haven’t had the problem since PS Audio swapped out my motherboard - tubes that seemingly had issues (6/7 volt mainly, pulsing) before play like champs now. Sorry to hear!
Thanks to all posting their experience with various tubes. Question for the Amprex 7308 lovers: How long did these tubes take to sound their best? I have been running with MATSUSHITA / NATIONAL PCC88 / 7DJ8 and had been absolutely enthralled with their sound in my system. I ordered up platinum grade Amp 7308’s from Upscale thinking they would be a sure improvement. After running them for 20 hours I swapped back to the Matsushita/PCC88/7DJ8. The 7308’s were dull in comparison. Less 3D imaging, less dynamic. Overall they sounded compressed with reduced detail and ability to resolve musical emotion. Was I too impatient or is this a system dependent result?
I am using a pair of 1952 Raytheon Triple Mica Black Plate 5814’s made for the Military though any of the 50’s to early 60’s Black Plate Ratheon’s are good especially the ones labeled for Baldwin Organ company as they were hand selected as Baldwin was there biggest customer. Another good tube is the RCA Clear Top. I have found the BHK to be particularly fussy about tube noise and matching so if you want to be certain then contact Andy at Vintage Tube Services and see what he has. If you want to try Ebay there are several reputable guys still selling the Baldwin Raytheon’s for good prices.
The Amprex’s are a little soft up top but have lush mids and a grainless overall sound.The Matsushita’s have a little more air and sparkle up top which may work better for your system. Should probably give them at least 100 hrs before you make a decision. You won’t have any trouble selling the Amprex tubes if you decide to let them go.
The National 7DJ8’s are one of the nicer sounding tubes that one can use in their BHK Pre, in my opinion. I think they do everything right and I think they sound very close to the Telefunken 6DJ8’s that cost 10 times as much.
The slightly mellower Amperex 7308 are sheer magic in my system, but my speakers need a little softening to get the system balance right. I don’t recall needing lots of break in time to tell that they were a very good match in my system. I bet it is just a system balance thing. And should you want to sell those 7308’s, well, just message me to talk! I love having back up pairs…
Thanks for all the helpful replies! Now onto tube rolling in my BHK 300’s. I was so enamored with the National 7DJ8’s in the BHK pre I bought a matching quad for the 300’s. They only lasted for ten minutes.
Back to the 6922’s for now but the good thing is I have couple of back up pairs for my pre.
One of the beauties and wonders of this hobby, finding a small tweak that yields fantastic but seemingly disproportionate results! PM me if you are still are interested in the 7308’s.
I’ve been continuing to buy and sell tubes to find the “perfect” tube (for me and my system of course )
I’ve found a really 7DJ8 A-frame Amperex tube that I think sounds better than the Tungsram 7DJ8. I know that’s a big claim around these parts. But it offers a little bit more than the Tungsram. More liquid midrange and more powerful bass. Nicely balanced treble. It’s not as polite as the Tungsram 7DJ8 so it might not appeal to everyone but it still has the musicality of the Tungsram - the bit that keeps drawing you into the music. There are other amperex and Holland manufactured 7DJ8’s out there which I haven’t tried. So there are other options out there if you want to take a bit of a punt and try something different.
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