For fun, I just installed a pair of NOS Amprex PQ White label E81CC's (12AT7's) that I had purchased for my CD player. I had to switch to the 12V position for those, compared to the 6V position for the stock 6922's. I will let them burn in overnight and listen tomorrow.
e\Each of those tube types, their variants and diff manufacturers will have a different sound. Try looking at Joe's Tube Lore over at Audio Asylum for description of each. FWIW, Joe does not like the sound of almost any 12AT7.
Yeah, I copied Joe's paper a couple of years ago and noted he doesn't even discuss the 12AT7. That is the only tube my CDP uses. He also doesn't like 12AU7, saying - "I would say this is a fairly unexceptional tube family." I found it interesting Andy at Vintage Tube didn't seem to like 6922 tubes, a few years ago when I called him to discuss retubing my SF Line 3SE. Some like 6SN7's in preamps for their "bigger" sound, and I found that true in an A-S MP3. BTW, the Amperex E81CC's sound different, but overall better in the Zoe than the EH 6922, although they do not seem to offer as much gain and they may not be as good as the 6922 at higher volumes. At low/mid volumes they are smoother, richer, more dimensional and maybe quieter, but that may be a function of tube quality and not tube type. Thanks for your thoughts.
I have a Zoe, and have acquired the following tubes thus far:
NOS Mullard 12AU7
NOS Siemens 12AT7 (early '60's)
NOS Sylvania 6BK7B
The Sovtek was warm, smooth and too weighty, and lacked some focus, detail, and dimensionality. I wouldn't say it's accurate.
The Mullard was a fantastic all-rounder. Rich & nice balance, but I was looking for more punch and midrange clarity. I'm now trying the Siemens. It's not yet broken in (20 hours or so). I'm very impressed so far. Very quiet, more 3d, solid bottom, and slightly more air, although w/ some grain and not as rich as Mullard's midrange (maybe after a few more days?). I've not yet tried the 6BK7B. About the others, I'm not sure if 6BZ7 is worth a try (the only one I can find is $8 a pair though), and I've read that the 12BH7 and 6922 are not low in microphonics and were not originally designed for pre-amp use... so I'm leaving them for later.
One odd thing I noticed when changing from 12AU7 to 12AT7 was that I had to turn the volume dial 40% higher with the 12AT7 to achieve similar volume levels. I was under the impression the 12AT7 tube has about 40% more gain than the 12AU7. So shouldn't it mean I should be turning the volume dial down instead? Anyways, I'll let you know when the Siemens has fully broken in.
Also don't forget the Zoe is a phase-inverting pre-amp, so you should reverse the polarity of your speaker cables (on one end) for optimum sound. Cheers.
Are you sure about the phase inversion? I did not know that. I will reverse leads and see what it sounds like. Keep me posted on your tube trials. I am in the process of getting a pair of NOS Amperex 6922's to try.
The manual doesn't say anything about phase inversion, and I don't have testing equipment to be 100% sure, but the Audiogon fellow I bought it from actually tests and writes technical papers for Soundstage magazine, so I'm taking his word for it. I'm very pleased with the Zoe, as it's right at home (center of it really) with the rest of my system, each costing more than Zoe.
I've read that NOS Amperex Bugle Boy 7AU7/7AT7 are some of the best. I'd love to also give Telefunkens a try. Can get used for about 1/2 price, which might be good as they usually have twice the life of others...
You may want to consider that many of these tubes have different load and gain levels and are not always interchangeable, even though they may look the same. If your preamp wiring cannot handle a load increase, you may incur some damage. For example, a 12AT7 and a 12AU7 look identical, however the 12AT7 has a gain of 60, while the 12AU7 has a gain of 19. If your preamp circuit was built for a 12AU7 and you retube it with a 12AT7, you are increasing the load gain to your preamp by over 300%.
Cyclonicman, I appreciate your comments but the Zoe is specifically made to operate with the range of tubes listed above. The preamp has a SATC (automatic tube adaptation) circuit and user switchable 6V/12V plate voltage, and the owner's manual specifically lists the tubes I listed above as all being compatable. One just has to remember to switch to the appropriate voltage, although yes the gains are different for the different tubes. Right now it sounds very good with some RCA 12AT7 black plates installed. I am still interested in trying a pair of premium NOS 6922 tubes, and currently looking into different sources.
Upscaleaudio.com has some premium (and expensive) 6922's in stock which you might want to check out. My Siemens 12AT7 has opened up nicely and is more fluid now as it's breaking in. I think I'll give tube purchases a break now as I can see myself living with this one for a while...
Did you notice an improvement upon reversing your speakers' leads?
Mitch2, I've read those old RCA 12AT7 blackplates are also very good. With the ZOE, are you finding that you're turning the volume dial to around 3 o'clock for reasonably loud volume levels, as I'm finding with my 12AT7s? I rarely had to turn it past 12 o'clock with the 12AU7!
Hi Keshiri, I still don't have the "feel" of the Zoe, and honestly have not paid too much attention to where the volume knob is set. It is a very nice preamp, and an absolute steal for the price, and I compared it head to head with the Vibe/Pulse. Interesting about the black plates, I have a special pair of them (blessed by monks or something) from Brian at AAudio in my CD player and they sound great. This pair in the Zoe was originally a little noisy in the CD player, but are absolutely quiet in the preamp. Maybe they were not seated properly in the player. I have only used the AT7's and the original 6922's in the preamp, but it seemed the 6922's had a bit more drive, and the AT7's are a bit richer and sweeter sounding.
Another pair to look at might be either a GE or Silvania 5751 or 5814. Would be interested in your take on one of these tubes.
After some more testing, I've found the Siemens ECC81 (12AT7) lacked some bass punch with most jazz & rock, and compressed at normal to higher volume levels. As you'd suggested, it may be due to lack of gain with 12AT7 in the ZOE. I put back the 6H30 but it was the same story: too much weight, not much detail, and very noisy. I'm now trying Mullard's ECC88, which is same family as 6922. It's similar to their 12AU7 but more space and midrange resolution, and the gain seems right: I don't need to turn the volume up more than half way.
This leads me to believe that 12AU7 and the 6922 family work best in the ZOE, as their gains seem right in my setup. I'm curious to hear how the Amperex 6922 sounds in this pre, so please do let us know. It seems the US-produced white-labeled PQ is the one audiophiles all over are after.
BTW, my system:
Technics 1200 tt
Plinius SA100MK3 power amp
Reference 3A Veena speakers
If you haven't heard the Siemens CCa from the '60s(grey plate under getter support),: you haven't heard all the music. The entry price is steep(I had to find three NOS, matched pairs for my BAT VK-D5), but worth every dime. I've had a wide variety of the 6922 family in my ARC pre-amps, California Audio Labs Sigma and Delta DACs, etc. and nothing has come close to the musical realism of this tube. If you are looking for "tube sound", "warmth", euphonics, or sugar coating: don't waste your money. All you'll get through this tube is the pure unadulterated signal.
Rodman99999, I'd love to hear those Siemens in my Cal Sigma/Delta. But, don't they use 12AX7a? :-)
I use 6h23EB's in my BAT (original version - no upsampling). Do you think there is a significant improvement over these when using the Sieman's you mentioned?.
Do you think these Siemens are rugged enuf for an ARC SP10?
Hi Newbee- You got me there!! It's been awhile since I've owned those CAL pieces and I've slept since then. BUT- You're absolutely right, and what I ended up with in there was the Telefunken ECC803S. If you're looking at that family(12AX7) what I said about the CCa applies here as well. I can't imagine ARC running a bias hot enough to shorten the life of a tube as rugged as the CCa(10,000 hrs expected). If they did the units would positively eat lesser tubes. Honestly- I've never listened to 6H23EBs in my VK-D5. I had Siemens E188cc's in it until I could find the three matched pair of CCa's(a pair from Brazil, and two from W Germany). Had to get rid of those original tubes ASAP(don't want to say, "Russian tubes" 'cause the unit itself was designed by one, and I love it). A less expensive experiment would be to try 6 E188cc's in there. If they are more musical: remember that the CCa's will be another magnitude of improvement. I don't believe you'd be disappointed at any rate. Even after going through finding three matched pairs and at the cost of entry! Happy listening!
Hey- Weren't the 6H23's what came in the VK-D5? If so- I guess I DID listen to them, and started tube tasting right away. One more thing: If you shop for those CCa's make certain you're looking at tubes from the 60's. They have a dull grey plate under the getter support. The ones from the 70's have a shiney plate and will sizzle your ear hairs(of course- some would call that, "detailed")! I you make the switch- You won't be shopping for another CD player for a long time.
My BAT, an early model (1997 I think) came with low noise Sovteks. Not much different (then) from the 6h23's - I thought the 6h23's might have been a tad, no more, warmer/smoother than the Sovteks but I was using them in my SP10 which is reknown for eating tubes (including the Siemens I tried in it - don't recall if they were 'grey plates'). So I gave up on all my fav' 6DJ8's/6922s and balanced out the rest of my system. I never tried Siemans in the BAT - I did notice though that it benefitted from very low noise tubes so I just kept life simple and used the same tubes in it as I did in my SP10. Thanks for the recommendations...........
Keshiri, I ended up taking out the 12AT7's and putting back in the stock EH 6922. Based on my limited experience with the Zoe so far, the 6922 tubes seem the way to go. As HP said, it is sort of fun being able to roll different tubes; but in the end I suspect the manufacturer already did this and put the most compatable tube type in the stock units. That said, I received the Amperex PQ USA White labels this week and burned them in a couple of days, then man oh man, what a nice sound. I have owned some pretty expensive gear, but I consistantly find the most expensive or most highly rated stuff is not necessarily what I like best. To me, this Lector set up (CDP 7TL MkIII and Zoe) is just great - very musical, dynamic, clear, quiet and just plain fun to listen to. I am currently running that front end into Cary 500MB monos and my Aerial 9's. I do have a wanted ad for another preamp (Lamm LL2), one I have always wanted to try, but I am not in a huge rush because everything sounds so good right now. Regarding your Zoe, I would stay with a 6922 varient, and personally I like the Amperex. I have used the CCa's Rodman99999 talks about in a SF Line 3 SE I used to own, and they are nice but maybe a touch on the clear/extended/neutral side of things compared to the better Amperex's which are a little more in the rich/organic/full-sounding camp - both have good bass.
"I have used the CCa's Rodman99999 talks about in a SF Line 3 SE I used to own, and they are nice but maybe a touch on the clear/extended/neutral side of things compared to the better Amperex's which are a little more in the rich/organic/full-sounding camp - both have good bass." Mitch2- This is a very accurate assessment of the sound of those tubes(good ear-Kudos).
Wow Mitch I'm glad your Amperexes are working great because I ended up checking for some last week (tube rolling's enticing) and got a decent deal at Ebay for a pair of NOS US Jan white label Amperex 7308 (from 1966). Can't wait 'till they arrive. I hope they're similar to the 6922 white pq's as I also like the rich /full sound. My Zoe's owner's manual states the unit is originally furnished with 12AU7, which I find also works well. Have you found the ideal tubes for your Lector cdp? Lector's upstream gear are obviously giant killers. I wonder how their power amps sound like. I'd love to get my hands on their phono stage, which apparently costs more than the ZOE...
Rodman99999, thanks for the comments - those CCa's are excellent (and expensive as you say), but I suspect they do more for some equipment than for others. They didn't seem to help the SF Line 3 SE too much, probably since it is already a little linear and forward sounding. I wasn't as good at system matching back then.
Keshiri, I didn't realize your Zoe came with the 12AU7's. Mine is the newer model with black side panels (a recent demo) and I believe it came with the EH 6922's. Brian at Aaudio said they have upgraded some parts in the newer model, but Lector always seems to be behind in the documentation department, so I don't know which parts. Anyway, with the PQ White label 6922's in my Zoe, the sound is fantastic in a very musical sort of way, with a full rich midrange and excellent bass, but maybe giving up a small amount to the best I have heard in the high frequencies (probably not a fault of the tubes). I do not have 12AU7's in the house, but I do have a small variety of 12AT7's I have used with the CDP 7TL. In general, I like the 6922's better in the Zoe than the 12AT7's, even the stock EH 6922's sounded pretty good - no less clear than the PQ White's but not as rich and without the quality of bass texture.
In the CDP 7TL MkIII, which only accepts 12AT7's, I have to say I like the RCA triple mica black plates I purchased from Brian the best, expensive though. I also liked some NOS Mullard's I tried, but not as much as the black plates, which display superior clarity and extension. The US Jan white label Amperex 7308's you are getting are also supposed to be a pretty good tube, let us know how you like them.
You're right Mitch- If a piece of equipment is already too bright or forward sounding, the CCa's might be too much(like a lot of cable mis-matches). I've found with the BAT VK-D5, CCa's and a pair of Kimber Select 1130s: everything encoded on the disc makes it to the rest of my system(nothing added, nothing missing). Great at reproducing the depth and width of the original recording venue's soundstage as well. This is what "tube tasting" is all about.
regarding the Zoe on tubes please remember the regular Russian 6h30 tube unless very closely matched can be as bad as a 6922 Sovtek the Best 6h30 which is very good is the DR designation this are the creme de creme scientific
grade and run at over $50 each I compared them and for sure they are very good and just a hair warmer then neutral.
Audioman58- pls provide contact info for supplier of $50 6H30DR.
lector zoe fans want to know where the best deals are on the 6H30 DRs.
thanks for any help. -ad
Best tube if your system sounds on the warm side are Siemens 12au7grey plate.I was running telefunken sounded great very warm but a little tubby in the bottom end.Put in the Siemens the midrange opened up with more depth and the bottom end tightened up with a bit more bang these are now my output tubes paired up with two amprex bugle boy tubes it sounds WOW! with my turntable.Pre amp is a jj electronics 243 from Slovakia.