Back on 3/09/08, I posted Part I of a comprehensive tube shoot-out. With best intentions, I promised a follow-up in a week or two. More tubes were on the way, and I wanted to include impressions using the 6H30 power tubes. I took my time investigating mods vs. adapters (do I really want to void my warranty?) and after considerable consternation, my MK III is now modded to use 6H30’s
New Drivers:
RCA JRC 6AK5 (1943) silver plates, square angled getters
Tung Sol 6AK5 (1965) flat grey ribbed plates, bent squared D-getters
Sylvania 6AK5WB (60’s or 70’s ?) shiny black plates with 3 vertically stacked, nearly square windows on opposing narrower walls, round halo getters.
Raytheon 6AK5 (1944) small curved black plates, flag getter
Power Tubes:
Electro-Harmonix 6H30Pi Gold pins (current production)
IBM 7044 tall grey plates, D-getters
- these power tubes were on hand for Part I but not formally reviewed:
Arcturus 7044 (40’s)
Tung Sol 5687 black plates, D or horseshoe getters
GE 5-Star 5687 (1961) jet black plates, halo getters
- All compared to Russian 6H6n-N (6H6Pi) - the “stock” power tube
First the new
Drivers:
The physical construction of my
RCA JRC 6AK5’s mirrors Penchum’s early Sylvania 6AK5 with silver plates and square getters (same tube different label?). Sonically decent, they are a lot like the 5654A GE’s I have and reviewed last time - a step up from the stock GE’s, but not in the league with Mobile Audios.
Tung Sol 6AK5’s - See my thoughts on the Amperex 5654 in Part I. They are kiss’in cousins - a nice step up from the RCA JRC’s
Sylvania 6AK5WB After reading glowing reports on the Gold Brand Sylvanias, I thought perhaps their less expensive brethren might come close. There are several different Syl-6AK5’s, so I looked for physical equivalents to the GB. These don’t have gold plated pins, and QC was likely less stringent, but hey, with a price difference of 5-10 fold, you can’t go wrong here. Great sound stage, outstanding midrange and vocal realism, … they are hard to fault. Balanced across the spectrum, and devoid of ultradetailstereophileitis. Penchum about wore out his Rush files in trying
, but he was hard pressed to distinguish them sonically from the GB‘s, so far. Lets just say they are among a small handful of tubes (maybe 3 or 4) that every LD owner should scurry to find. There is synergy here, regardless of your front end or headphone choice.
Trapper32 posted his love for his
Raytheon 6AK5’s, above and beyond the Sylvania WB - “I think the Raytheon's have a cleaner sound with more air if that's possible, more detail…” @$20 delivered for 10, I couldn’t say no. Do they better the Sylvanias?
These can sound really good, but they are prone to microphonics, more than any other I’ve tried. Have you ever heard a school yard swing set on a windy day? The chain-swings causing the metal pipes to ping and sing? It’s interesting, because you can hear this with the volume all the way down by touching the volume knob, or lightly tapping on the HP cord near the plug end. Ok, sitting back in my chair with the music at a good clip, the problem is no longer on the radar, and - they do indeed compete with some of the best tubes. “A bit more sparkle”, yep… I’ll have to play around with the several pairs I have and update y’all on these later.
Power Tubes*
E182CC, 5687, 7119, 7044, 6900 varieties seem to fetch a premium price on eBay for whatever reason. Bargains are rare, and many $4-ish drivers sound awesome. It’s been said that power tubes represent 15-25% of the sound signature equation, drivers 75-85%. So… Why bother? Hmmm..
The
IBM and
Arcturus 7044* tubes are identical in construction. In viewing pictures on eBay listings, I have concluded that both are re-badged Sylvania 7044’s - I don’t own the Syl’s, but these two sound the same. These have been my favorite power tubes. They impart well defined bass and warmth compared to the stock 6H6Pi’s and are my default choice in complementing every EF95 tube I’ve tried.
The
Tung Sol and
GE 5-Stars 5687 power tubes* are fairly similar. Both feature detail enhancement. The TS - considered the gold standard of 5687’s, are more harmonically rich, and I prefer them to the 5-Stars somewhat drier more detailed flavor. Both work to complement the darker signature of EF92 varieties I’ve tried. These positive qualities with EF92’s are a mixed bag when paired with EF95’s (to my ears). If you really dig detail, your opinion might differ. Keep in mind my phones of choice (K701’s) don’t need a boost in this category. IMO YMMV
What about the
stock 6H6Pi power tubes? How do they sound compared to the adaptable options just discussed? Good news! They hang in with the vintage boutique glass very nicely, thank you. Without compromise IMO. Just a wee different.
The stock tubes can easily be described as neutral - right down the middle of the playing field. A skosh less warmth and bass strength vs. the 7044’s, a smidgeon less detailed head to head with 5687’s. Keep in mind however, two EF95 varieties compared may offer less differentiation, so the 15-20% rule is a moving target. I‘d widen the range to 15-30% depending. That’s about all that needs to be said. Mix and match is the whole draw to making Bullplugs. Enhance your fun and massage your inner tweak bone, or just leave it to us nut jobs
Enter the
*EH 6H30Pi gold pin, the stock power tubes in a LD MK IVse. I’ve had these kicking around for awhile now, but until last week they couldn’t be evaluated in my stock MKIII. If you haven’t followed the story line on these; first they were listed as compatibles in the MK III, then they weren’t, then it was determined you had to Mod the board to use’em. My hope was for some kind of Bullplug2 solution, but that didn’t pan out. I ended up installing a switch using Webghost ‘s approach. Thx WG! And dgb1 2!
The 6H30 tubes are far more substantial to the eye and hand. They make all 5687/7044 and 6H6 units appear utterly flaccid! Does structural manliness equate to sonic balls?
Well, much like a sprouting teenage boy, the 6H30Pi’s need some time to figure out what to do with their new found manhood. Early in their burn-in, things wandered around quite a bit. Dynamics had a surging unnaturalness and harmonic structure was pinched. With 80 hours and counting, they’ve lost most of their youthful awkwardness.
My Mk III needs a jock strap! There is weight and control that other power tubes do not deliver. Perspective is deeper, notes are sharpened, highs are quick and detailed but not forward, and the frequency balance leans a little to the dark side, much like the above mentioned 7044’s, which I like. These bring out more bass slam than I’ve ever heard through my K701’s.
About the only thing they seem to diminish is harmonic richness, making notes disappear more sharply than I’m used to. More hours needed? Perhaps, but I’ve read in comments by Audio Research owners that many miss the harmonic qualities of older 6922 based units. AR has redesigned most of their gear to use 6H30’s.
On the subject of tube purchasing styles, I’ve gone about it like I’m sitting at a large table in a Chinese restaurant, with a bunch of adventurous eaters. It’s a cheesy joint but the food is good. Sharing is great fun! Find a head-fi buddy or two and trade a few pairs. Everybody learns what to order next time.
*NOTE!
The EH 6H30’s require soldered resistor changes in the board, either switched or un-switched, thus voiding your warranty.
The 7044 and 5687’s require pin reconfiguring adapters, these adapters will also open your power tube choices to include E182CC, 7119, and 6900’s.
Hope you enjoyed my shared indulgences,
E
How to make Bulldapter bullplugs:
http://www.head-fi.org/forums/f5/rev...ifiers-301219/
Big Ass tube review Part I:
http://www.head-fi.org/forums/f5/lit...ml#post3921663
