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I have an Eico HF-86 Integrated amp. The amp uses 12DW7 X 2, 6BQ5 X 4 and a 5AR4 rectifier. This amp is really good sounding but NOS 12DW7 and 6BQ5 are pricey and getting pricer.I have been using a NOS Raytheon or GE 12DW7 pair with either NOS GE gray plate X 4 or a mix of Sylvania black plate 6BQ5 + Tungsram EL84 that came with the amp. Just yesterday I put in a new set of JJ EL84 X 4. I have been using a Sovtek 5AR4 with some experimentation with a TS Reissue 5AR4. The Sovtek 5AR4 is in the amp today.
I decided to give the JJ a try and I am happy to say the tube sounds excellent right out of the box. The JJ is a clear, clean sounding tube like the Raytheon but with much better bass. In fact, the JJ has better bass than any 12DW7 I have tried in this amp or others. At times the bass could sound slightly tubby but depending on the material this has been a plus or minus so far. Note: after three hours of playing the bass seems to be improving with the tubby sound receding but the strong, powerful foundation remaining.
The mids are well resolved and neutral. There is no richness that stands out here but the tube is in no way thin sounding. The mids flesh out guitar very well ... a must with me. Vocals are just right .... no sibilance or excess breathiness but words are fully discernible. Small inflections to vocals are coming though unscathed. The mids just sound right to me.
The treble is smooth, well integrated and less bright than the Raytheon 12DW7's I had used with the JJ EL84 since yesterday. That might seem that way because the bass is stronger with the JJ giving a better overall balance. I am not sure. Resolution seems similar and I don't feel any air or sense of space is missing. I have the Allman Brothers Live at the Filmore 6/27/71 playing right now and I can hear the drum interplay and cymbal crashes with no edge or resolution lacking. Duane Allman's guitar sounds fantastic.
Bottom line I think we have another new production tube in the winners column. The JJ 12DW7 joins the JJ ECC803s, JJ ECC99, JJ EL84, Sovtek 6L6WXT, Sovtek 5AR4, TS Reissue 5AR4 and TS 6L6G as tubes I enjoy listening to as much as my NOS tubes.
Robin Trower Bridge of Sighs is on now and the overall sound, especially guitar sounds fantastic .... fast, clear, alive and dynamic but no edge or spittiness. Impressive!!
PS: I got these 12DW7's from Jimmy McShane. I ordered them Friday and got them today. Jim says he screens these for noise and these tubes ARE quiet ... along with sounding unexpectedly very, very good. I am one happy guy.
Edits: 04/21/14 04/21/14Follow Ups:
No way do they compare to my Mullards. I use them occasionally in my a Fisher SA100, usually for testing purposes, but they are not far off from my Matsushitas. They don't have the soundstage that I really like from that amp.
The JJ is almost as neutral as my Teles, but without the punch. I have at least a few hundred hours on them, but my Mullards from Andy Bowman and Byrd69 are what I switch back and forth with. I'm glad I have few more pairs stashed away.
But, they are the only JJ tube I have liked yet.
I was looking for something to do with the second Dynaco SCA-35 I have. I figured I'd convert it to a ST-35, since there are boards available, which would make it a fairly easy project. I even bought a new chassis for it (picture from ebay ad shown above). The chassis is the same demensions as a ST-70, so I figured I would add a choke to the power supply, and have myself a great amp.
I bought a pair of JJ 12DW7, also from Jim McShane. I sent them off to a friend of mine, who was using a Fisher SA-100 (which uses two 7247 as input tubes) to drive his Altec 604s. I wanted his take on the tubes, prior to building my amp.
His opinion was that the JJ 12DW7 were "just OK", compared to whatever old stock 7247s he was using. He went into more specifics as to where he felt the JJ tubes fell short, but it's been several years since he gave me his assessment. I've emailed him this morning, asking him to refresh my memory. I do recall that he sat his wife down for a listen, and she liked the 7247s better too.
If I had a working amp which used 7247s, I'd be happy to find an alternative to pricy NOS, I suppose. But since I'm starting out with a scratch build, I've decided to look for another input stage (which I'll have to wire point to point), one where I won't have to pay through the nose for NOS 7247s, or compromise with the JJ 12DW7s.
Disclaimer: I've never heard the tubes in question, so take my 2¢ with a grain of salt. But I do trust my friend's ears. The only drawback is that instead of having a working ST-35, I've got another project added to my post-retirement list. And God knows when that will be!
I just got off the phone with my friend who tried my JJ 12DW7s. He did try them in his Fisher SA-100, but also in his Fisher 400 CX preamp, where the differences between the 7247s and the 12DW7s was more readily apparent.
He let the JJ's run in, in the 400 CX for eight to twelve hours per day, for about five days, prior to comparrison.
He said the differences between the tubes in the SA-100 weren't as large as they were in the preamp. But his sonic assessment was that the JJs were "Smaller, more closed-in sounding" than his 7247s.
Are you sure they were fully settled in? I don't know why but many new production small signal tubes need a lot of hours.
Recall some years ago found a NIB NOS pair of RCA/Mullard 7247 at a local electronics warehouse in Utah.
Plugged them into my ST-35 and the were HORRIBLE!
Swapping out with the original US made GE 12DW7, old tube won easily.
But then, after just a few hours use, the RCA/Mullard broke in and NO CONTEST.
Always wondered after that, just how often I actually received the NEW NOS Tubes I paid good money for. ;-)
Ivan, I've been there too.
And since I wasn't there, I honestly can't say how many hours my friend put on them, prior to his and his wife's listening sessions.
I will say that he's been listening to, building, and repairing tube amps for more than thirty years. That doesn't mean is opinion is infallible, simply that I chose not to build an amp around the JJ tube, based on what he heard.
I'll ask him more details the next time we talk. And honestly, I'm hoping you're right (along with the original poster), and my friend's wrong. Because I have almost everything here to build a working ST-35, except for the aforementioned 12DW7s and the parts for Dave Gillespie's EFB, which I was going to set up for individual output tube biasing.
I did Dave's EFB mod to the SA100 I mentioned and it was well worth it. You can read about it and my panicked brain fart when I installed one of my bias caps backwards in Dave's AK thread on the SA100.
A great upgrade to the amp. I highly recommend it. And now with better operating points on the output grids, I don't have to run 7189s if I don't want, and I plan on tube rolling a bunch of different 6bq5/el84 quads.
snip.... and I plan on tube rolling a bunch of different 6bq5/el84 quads.
All of the sudden there was an unprecidented demand from Nigeria for 6BQ5s and Byrd's stash was completely gutted, leaving notben to use whatever he could dig up out of the lower third, if anything.
"I can't compete with the dead". (Buck W. 2010)
Snip:
"All of the sudden there was an unprecidented demand from Nigeria for 6BQ5s and Byrd's stash was completely gutted, leaving notben to use whatever he could dig up out of the lower third, if anything."
Maybe the Teles are hiding in that bottom third.
I'm certain the Teles have all been sifted out by now and sent to the other room for long distance hoarding. There may be a few WEs, or Rad-Tel near the bottom, but no Tele for you.
No U-Hauls allowed.
"I can't compete with the dead". (Buck W. 2010)
I just thought I would post an update. I like the tube set in the Eico amp the more I listen. The tubes are all new production.!!!The JJ 12DW7 has become better balanced with more run in. The bass is less prominent and there is no more boom. The bass, however, remains the strongest of the 12DW7's I have used.
The mids have possibly richened a little. The sound seems fuller today even though the the bass has receded some. I am listening to Sherman Robertson "Guitar Man Live" and the guitar and vocals explode out of the speakers. The mids have definitely picked up some dynamic kick. The JJ EL84's are almost new too so maybe they have matured some as well.
The treble is well above average good. I don't like an overly detailed treble and any excess sibilance sends me running from the room. The JJ treble is detailed and smooth and the highs are just there .... well integrated with no spotlighting or edge. The treble is not as airy as with the Raytheon 12DW7 but the center image is tighter and more solid .... which I personally prefer. I could see where some could say the JJ is more closed in. But the tube is also more focused to me.
Again, I was pleased to begin with and I hear improvements to the sound as the tubes get more hours. I always avoided most JJ tubes because of reliability issues but the good JJ's are really good.
Edits: 04/23/14 04/23/14 04/23/14 04/23/14
Post again after more hours. The JJ EL84's need time too..at least that has been my experience. I have been trying the JJ ECC803s and it is a nice tube too.
It is also possible that in your application the JJ was not optimal.
That is very good news about the 12DW7 because I don't have very many mullard 7247s but it just goes to show that people need to wake up and realize that new old stock tubes are almost extinct and it's either support JJ,New Sensor,and Shuggie,or not get any reasonably priced tubes in the future..I wish they would also realize that because a new production tube sounds a bit different than say an RCA or Sylvania,doesn't mean the latter two are better,it means they sound a bit different..Anyway that 12DW7 is wonderful news for Dynaco ST-35 and Eico ST-70 owners as well as Scott 4310 and 310E tuner owners.
Honest amplification is better than excessive 2nd order distortion anytime.
I still but old production..mostly used but the pickings are getting slim. I do have some gems and use them when I am going to be in the sweet spot for a while. New production can get close and they are my every day tubes.
The JJ ECC803s is a nice tube and so is the price.
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