WA7 & WA7tp Tube Rolling: Part 2
Please remember that the sound changes I describe are relative to the other tubes and made during focussed listening test. In typical, relaxed listening (rather than focusing on particular aspects), the magnitude of the change might seem much less. We are talking about many many orders of magnitude below just using a different pair of headphones.
1. The Brimar CV4003.
Price: £15 each
Availability: good
The Brimar CV4003 is another British-made military spec 12AU7, with fine spindly white print that seems to smudge off merely by looking at.
Listening to
First Aid Kit’s album “Stay Gold”, which is a highly engaging album, I could hear a dose of that pleasing Mullard smoothness in the mids but something felt off about the overall presentation with the Brimars. The sound is simply
too relaxed. This is the result of a combination of factors: Firstly the bass is a little woolly and lacks extension and attack. Definitely not a toe-tapper. Secondly, the treble has a significant roll-off and high notes struggle to find a place for themselves above the generally congested sound. Even the mids are basically a little veiled.
Avoid.
2. the Tung-Sol 12AU7 re-issue.
Price: £12 each
Availability: excellent!
The Tung Sol 12 AU7 reissue is an excellent performer for the money. It reminded me of the stock 12AU7s but much improved. The sound is balanced, with great transparency. Switching from the Mullard CV4003s I definitely noticed a boost in clarity and crispness as well as a more spacious soundstage. Music is less focused on the mids. Just a little warmer than neutral, but not by too much.
These tubes may be overall more fatiguing. Certainly not as user friendly as the Mullards and less tolerant of the random lower quality recordings that Spotify seems to throw out with some regularity.
Likewise, the very “live” sound they impart may verge on
raw for some listeners – but for the most part I felt this was more to their credit than their detriment.
Great for those that don't want to play the NOS tube game.
3. Philips ECC82 - Herleen factory
Price - £35+ matched pair
Availability: very good.
Philips owned and ran tube factories throughout Europe so their tubes appear branded with many different logos. I was looking specifically for those produced in Holland in the early 60s. Mine were branded “Valvo” which often meant they were produced in a German factory, but the factory code and small Delta type symbol indeed reveals that these came from the Herleen plant in Holland, 1960.
The low end - It’s quite boosted in comparison to the others. It’s not as detailed as the bass on some of the others. Although there’s a decent sense of attack in the mid bass, In comparison with the Mullards and Tung-Sols it’s perhaps a little looser and can bleed into the mids - though not unpleasantly so. I quite like it, especially in combination with the thinner WA7 DAC.
With the obvious caveat that if you’re looking for neutrality then the elevated bass could detract from certain areas, the rest of the sound signature is also impressive. Through the middle, the Philips exhibit good resolution producing a smooth sound with a nicely detailed texture and perhaps a slight preference for clarity, delicacy and separation over the Mullards, which are a bit richer and more fluid.
Compared with others, very little music will sound harsh with these tubes. Good stuff.
4. RCA-Cleartop
Price – £25+ matched pair.
Availability - very good
I believe at one point this was an upgrade-option offered by Woo directly for the WA7tp, though I’m not sure if my tubes are comparable. RCA tubes appear under many different logos and brands.
They are lot richer than I expected, with a warmth that is of benefit to the WA7/DAC stock signature. They are certainly not a lean or thin sounding tube and have really nice, deep impactful bass performance. Probably one of the cleanest tightest bass performances of the whole bunch, which was a pleasant surprise to me.
The main characteristic of these tubes is their lively and engaging presentation that has vocals front and centre and instruments - though reasonably well separated - playing closely and clearly in a relatively small soundstage.
For my own tastes the sound is a little too strident and “inside your head”. At times music seemed quicker and more out of control than it should have been for some reason. Certain instruments like pianos seem to clatter and smash their way to the front.
5. The CBS-Hytron 5814a
Price: £70 matched pair
Availability: uncertain
This is an old tube – 1955. My understanding is that the CBS-Hytron 5814a can be broadly broken into 3 categories: the very early 50’s white label, the 1955 red label slanted getter(mine) and the later blue label. I’m informed that the first two are the ones to go for, with the first having the slight edge.
It’s a excellent sounding tube in the power supply. This one is up there in the top 3 for me. To make an instant comparison with the Mullards - this is a tube that performs well throughout. Yet it delivers a little extra clarity in every single area. The tone is one that is essentially balanced and natural but with just enough of a little helping of sweet tube magic note decay.
The soundstage is wide but also deeper and three dimensional. Listening with this tube routinely gave me more toe-tapping and goose-bumps moments than any other.
One of the best IMO.
6. The Siemens ECC82 Silver Plates
Price: £80+ per pair
Availability: okay
These tubes are easily identifiable by their striking shiny nickel ladder plates. The date-codes on these were nearly completely rubbed off but just enough remained for me to pinpoint these to 1961 from the Siemens & Halske factory in Munich.
These tubes were wider sounding than the others I tried. Their main strength is the clear & expansive sound they produce. it feels larger than any other tube I listened to. Although its often a small change, it can help push instruments a little further outside your head.
Within that soundstage - in terms of tone, timbre, high-end extension or bass presence - it would be hard to find fault with anything that Siemens ECC82 does. Please don’t think that this is a bright, sterile or analytical sounding tube. I didn’t hear one piercing note while listening to the Siemens. There is a lovely inner warmth and musicality to the sound that is clean and accurate.
Highly recommended.
Returning to the WA7's amp tubes - Soviet-era 6C45s
Price - £25 matched pair
Availability - good
I’d been aware - since the WA7 release - that a few people had experimented with NOS 6C45s – these were the original 6C45s produced in the 70s/80s (possibly earlier) before the reboot under the name “Sovtek” and the rebranding under “Electro-Harmonix”. Recently a couple of knowledgeable Head-Fi’ers suggested that it would be well worth checking out the NOS tubes since the production quality of Soviet-era tubes often eclipses the less-than-stellar quality of modern-day Russian tubes. Obviously this was somewhat contrary to my generally positive experience with the Tung-Sol reissues in the WA7tp.
I tracked down a pair with a factory code from ‘1977 – again hailing from the same factory in Saratov, Russia. A visual inspection confirms that, besides a slightly cleaner and shinier getter flash, and the “Reflektor” factory logo, these are identical in appearance to the Sovtek branded 6C45s in every way.
Well, I’m happy to say it’s a good sounding tube. Unfortunately, so is the Sovtek 6C45 and these puppies sound the same to my ears. As much as I would prefer to have a tube of
historic value in WA7 – I just can’t hear a difference through my equipment. After fairly extensive listening it seems that when the New Sensor corporation re-started production under the name “Sovtek”, they may have just hit the big red button and picked up exactly where Reflektor had left off, with no discernable change to sound - at least not one that is discernible to me with this gear. The continuity between Reflektor/Sovtek tubes may also explain why some users of the Sovtek branded 6C45s (in other applications) have reported receiving some with 70s/80s factory codes: New Sensor were probably seamlessly rebranding old-stock.
Final Thoughts:
As a final test I decided to give the stock WA7/tp a re-listen and popped the Sovtek 6C45s and the Woo-Selected 12AU7s back into the mix. What struck me most is that if you’re not the type to tube roll and you’re still rocking the stock-tubes – don’t sweat it, you’ve still got a very nice amp.
With the caveat that the top 4 or so could easily be rearranged based on individual taste, my own final order of preference would be as follows:
1. CBS-Hytron 5814a
2. Siemens Silver Plate ECC82
3. Valvo(Philips – Holland-made) ECC82
4. Mullard CV4003
5. Cifte 12AU7
6. Tung Sol 12AU7 reissue
7. Sylvania JAN 5814a
8. RCA Cleartop
9. Stock 12AU7s
10. Psvane 12AU7
11. Brimar CV4003
Ultimately It’s just a case of counting your pennies and picking your poison.