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Review: Comparison of 5751 Tubes Raytheon, Sylvania, and more Tweak

Category: Accessories

Okay..for those of you who use tube amps (especially by ASL) I have compared the following 5751's. 5751's are military tubes which can be used in place of 12AX7's.

Tubes:
Reference Ei EL84’s
Raytheon 5751
RCA Blackplate 5751
CBS 5751
Arcturus 5751
Sylvania 12AU7
Tung-Sol 5751
G.E. 5693
ITT 7025
Sylvania 5751
Music:

Mahler-Symphony No. 4 by London Philharmonic

This CD is my reference classical cd. It has highs, lows, everything one could want. It seriously tickles my spine when I listen to it.

Eric Clapton- Reptile (HDCD)

This is Eric Clapton’s most recent album (note that I saw it live in concert last year in LA hehehe) It has some male vocals, and plenty of strings. Another great album

Pink Floyd-Echos

This is one of Pink Floyd’s most well-recorded albums. It is basically a sampler/remaster of their work from the 1960s-1990s

David Bowie-The best of the BBC Radio Sessions 1968-1972

This album is a challenge for most systems. A perfect example of great music recorded with not-so-state of the art equipment

Anggun-Snow on the Sahara

A great example of superb female vocals
Motley Crue- Dr. Feelgood

A classic Metal/Rock band

Impressions:

Raytheon 5751
Very sweet, warm vocals. Very open soundstage. With classical, you really feel the vibration of the violin strings. It is very warm and very nice. It really gives a distance sensation. The Music’s presence is really there. I would say this is the best tube for any type of rock music also. It sounds similar to the CBS 5751 with classical and Jazz.

RCA Blackplate
These are probabally the best for Pink Floyd. I hate them for heavy metal though, it sounds muffled. The vocals and highs aren’t really as dynamic as with the Raytheon. Altogether, this is a nice tube for the money. It certainly beats up a lot of others I have experienced.

CBS 5751
This is a very rare gray plate 5751. It sounds extremely deep with classical. It is absolutely fabulous with male vocals. It is quite forgiving of bad recordings also. This is the tube to get it you are a big fan of older jazz recordings. Also note that flutes sound great with this tube. It did however have a slight buzz on the low end. This is one of my favorite tubes because of smoothness it puts out.

Arcturus 5751

This is a nice heavy metal tube, IMO heavy metal seems to be a bit bright, but not at all with this tube. The big con with this one is the soundstage. The bass is the strongest feature with this tube.

Sylvania 12AU7

A bit too soft for my tastes. It sounds a lot like the stock JJ tube, skip it.

Tung-Sol 5751

The most liquid of all the tubes, It lets the highs just roll off. Very low-noise. I am in love with the liquidness of this tube. Not as dynamic as the Raytheon, but superior with female vocals and horns.

G.E. 5693

This tube is a nice all-around performer. Not super-dynamic, and not too smooth or soft. Good buy for the budget tuberoller.

ITT 7025

Despite what nick says about this one, I really do like it. It has superb imaging. It sounds great with strings, and the bass is really there. The sound is very realistic, not too liquid. I’m sure you all know how I prefer realism and accuracy to warmth. This tube is a very solid performer.

Sylvania 5751

Wow, now here is a tube I didn’t expect to be as nice as it is, especially with the gold brand to compete with. This is a great tube, very solid buy. The dynamics are great, and they reproduce the sound very accurately. The imaging is great, I can close my eyes and actually be at the show. Highly Recommended

Here is how I would rank all of these tubes

1st – Raytheon 5751
2nd – Sylvania 5751
3rd – Tung-Sol 5751
4th – ITT 7025
5th – CBS 5751
6th – RCA Blackplate
7th - GE 5693
8th - Arcturus 5751
9th - Sylvania 12AU7

I would recommend all of these tubes except for the last one on the bottom. It really depends on what type of music you listen to.

Associated gear
Hospital Grade Power Cord
Denon DCM-370
Rhino Interconnects
MG Head DT
Sennheiser HD600
timschirmer
nurxhunter
11 posts
 
Well, I take back what I said about the Raytheon 5751 either 3MBP or 2MWMG. It a great tube. Lively as Joe puts it, good bass. The mids are not smeared at all, yet have a great touch of warmth. Wonderful wide stage with air as well, but maintains linearity and precision. Joe got it right. I think, right behind Sylvania 3MBP. All mine in late '50s. SUPER in DAC stages.

Grey plates always sound to me airier and warmer than BPs, esp. true for Sulvania 5751, as in Joe's review. I agree with many that while Joe nailed the 5751 characteristics so well, he dissed on 12AX7 in comparison. Valvo Hamburg and early LP Philips are excellent (all EU tubes are grey plate). Airy and holographic with wonderful, natural mids and decent bass--the mids shine, however. Also, very early USA blackplates with bent D-getter or corner square getter 12AX7 ('51 is as early as I have) and 1960 or so Raytheon 12AX7(A) shiny blacks are great 12AX7 comparable with the best 5751, IMO/TME in various amps and DACs.

Joe also dismissed the 12AU7 type; however, Early Amperex, Siemens and Valvo Hamburg LP D- getter and even the short plate halo getter from early-mid '60s and slant-halo Valvo Hamburg and certain 5814 brands are spectacular, in my opinion, as is 7316 Can't just dismiss these. Nope.

I am thinking of doing a 12AT7 review. Guess what--the more expensive and rarer ones homologous to 12AX/AU7 sound super in 12AT7, as do all the 3Mica /ECC81 and ECC801S I have tried, as well as CBS 7728. Tungsol early-mid '50s with D-getter grey plate 12AT7 are the only USA 12AT7 that I think sound close to big league.

Grain of salt: my 12AU7 and AT7 impressions are from one amp: The Ear Max Pro with HD650/Cardas and other HP and great ICs. So, I can't speak well for how these sound in stereo rigs--and that's quite critical. I am hoarding for the time I spring for a 12AU7 based PA or IA.

So, the Yankees own the 5751 and the top tier are super, in league with any 12A out there. The Dutch and Germans own the 12AU/AX7 flavors, on the whole, with some competition from Yankee black plate 12AX7, and possibly Tung-Sol LP 12AX7, '50s bent D-getter.

Its always worthwhile experimenting by sub-ing 12AT7 and 12AU7 and even 12AX7/5751 and 12AT7, with some caution.

Finally, in my opinion, Joe's review of 6DJ8 variants is absolutely and remarkably impeccable. Thanks Joe!!!!!!!
gonzalo's avatar
gonzalo
38 posts
 
My 2 cents are based on tubes used as drivers for input section on an integrated amp driving 6SN7's with output tubes KT88/6550's also used with CAL Alpha instead of 12AX7's
The best one for the CAL Alpha is simply the Tungsram ECC83 (12AX7) 100 Mu tubes.
I have tried mullard blackbourne, RCA 7025 black plates, Sylvanias, Amperex, Telefunken smooth plates (Very nice indeed), and a few new production like EH, SHuguang 12AX7A, also the B's (worse than the A's .. .) EH 12AX7.
The GE black plates and gray plates in both versions 2 mica & 3 micas though they are wonderful all of them the Tungsram for the CAL are simply the best combination of bass definition, mids liquidity and top end purity creamy and lively qualities.

Now for the amp driving the 6SN7's i think it is a matter of tubes you use to combine them with and then the synergy with each tube that comes after the chain. in the case of Sylvania's chrome tops (6SN7 GTB)the Tungsram ECC83 were a little bit too bright (I/m nit picking here by a hair), using RCA gray glass 1940's 6SN7 GT and GTA's then the Sylvanias 5751 (BP 3 Micas) took the cake, now I am using a combination for the 6SN7 of Tung-Sol and Zenith branded GE made black plates long envelope (2 and 2 in mirror matched per channel configuration) on that configuration the GE 5751 3 mica black plates just has no equal.
Note that this is driving a quad of Tung-Sol 6550 gray plates 1965 well matched and bias adjusted to +- 1% or each tube. in triode strap. though Ultralinear sound good for 70's rock and reggae, the Triode modejust does magic on all the other music, jazz, voices, classical, R&B, Blues, etc. etc.

So . .. to me the synergy of the tube with whatever comes after in the circuit, and probably before also is the essence of how the sound of the tube you will prefer, also take into consideration the rest of the circuit and that sometimes the 68 Mu gain from a 5751 may not be enough to drive the rest of the circuit compared to a 12AX7 that has a gain of 100 Mu. you need to check on that also
However be warned these tubes are expensive and hard to get choose wisely.

Enjoy the music;

Gonzalo
dwhall
6 posts
 
I've been using a Sylvania (KUHL - Cryo - yellow printing) from TubeWorld that I got about a year ago with a MapleTree Headphone Amp. I am very pleased with the sound and highly recommend it. Extended highs, deep/tight bass. I use Sennheiser HD600 and AKG-501 headphones.
zeal's avatar
zeal
174 posts
 
5751 replaces 12AX7's, so how do the Sylvania 12AU7 fit in. Its a different tube. No wonder it's on the bottom of your list.
mechans
3,048 posts
 
12AU7s are a very low mu or voltage amplification tube. It is unusual for them function well in place of a 12AX7. But 12AU7s are frequently used in circuits as drivers for the 12AX7s. As a double triode I guess they can be phase splitters as well.
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