New compared to NOS tubes

[Dr Morbius]

Hi, I was wondering if anyone has a tube amp that uses the old "7591" and "7591a" tubes and if they ever replaced them with the new JJ 7591S tubes from Tube Depot? And if you did, were you happy with the sound, or disappointed??? Inquiring minds, you know..................

Thanks,

Steve

[Daddy Dee]

I've been using the JJ's in my Fisher 500B with pleasing results.

One thing about tube amps and tubes, there seems to be a huge synergistic thing going on. With my Wright 2A3's didn't like the EH tubes at all. REALLY didn't like them. Another forum member shares the the EH 2a3's are his fave in his Moondog (maybe) 2a3 amp.

[Marvel]

Another forum member shares the the EH 2a3's are his fave in his Moondog (maybe) 2a3 amp.

That's because they came with it, along with a pair of Sovteks. But they really seem to work well in them. Drivers are RCA NOS with a Mullard NOS for the rectifier. I need to get back ups for everything, as I've not purchased anything since I got the Moondogs and that's been a few years.

One thing about tube amps and tubes, there seems to be a huge synergistic thing going on.

True, and probably one of the hardest things to sort out. Just like some amps and speakers don't play well together. It could turn someone off to tubes altogether if what they listened to wasn't quite right.

Bruce

[seti]

I have a friend with some Wright 2a3 amps and they sounded really good with most tubes and the chinese 2a3s. But he has a massive stash of tubes including NOS 2a3 tubes still in the boxes. He rolled through these until he found a pair he liked. He also used the red base rca 5692 and a Bendix military rectifier. The combo of all these tubes took the amp from really good to absolutely incredible. I mean huge difference. I'm not sure if it was the primo 2a3's or all tubes combined.

[mark1101]

I have a rebuilt HH Scott LK-72 and have used both the JJ and EH 7591s. I am currently using the EH tubes and have been happy with them. The unit itself has strong bass output and I felt the EH had better synergy with that characteritic of the amp. The JJs seem to produce a different sounding more pronounced bass output which was just a little too much for my taste and that amp.

Just a matter of taste.............nothing wrong with the EH nor the JJ.

[Dr Morbius]

Yes Mark, but have you heard your Scott amp with an original set of 7591 tubes and was there a difference? I have a Scott 299D with original tubes and wondered if anyone compared the original to the JJ's to hear a difference???

[mark1101]

No, I never saw the orginal power tubes. The amp was smoked when I bought it and Craig NOSValves rebuilt it. I can't remember what tubes were in it for power tubes. I have always used new production power tubes. But the preamp tubes were NOS telefunkens. I have long since replaced everything with new production and I am happy with the sound for a kit built unit from 1960.

[Daddy Dee]

Steve, are you considering any tubes for backup? If so, IMO the JJ's would be an excellent choice. I'd love to hear your take on the tubes.

My listening for comparison was just casual. I had a Fisher 800C with the original tubes. Sold the receiver with tubes intact to a forum member. The 800C was rebuilt nicely and I did considerable listening and thought the sound very good. At the same time was also listening to the 500B with JJ's. Didn't do any tube rolling or pay attention much to the tubes. In my casual listening I didn't notice any difference at all. With intentional listening a difference might be discerned. I wouldn't expect much dif to be heard, though.

[joshnich]

I have in the past owned a 299D and still do own a Mac MC225 which also uses the 7591. I have used both NOS and the new 7591a I would say the newer versions have a little mor oomph and the nos ae a little more delicate. Very little difference - at least to me.

Josh

[sunnysal]

as people have mentioned, tube rolling is SO system specific that recommendations IMHO are almost worthless unless people have exactly the same equipment. I have used old and new tubes and found some NOS tubes I loved and new tubes I loved. part of the fun of the hobby is trying out tubes and finding out whats sounds best to you in your system. One revelation for me was that I have discovered that my rectifier, output and input tubes ALL have an effect on the sound of my system, after playing around for a year I have a NOS tube in the rectifier and input positions and new tubes in the output position. my problem is that if the NOS tubes go bad I will have to try to find more that sound as good! whereas if the new tubes go on the fritz I can just buy more. enjoy the process and most of all....enjoy the music! T

[mark1101]

This post made just above jogged my memory on something worth mentioning. I agree with the post above first of all. Good points.

I have spent a small fortune on tubes and what I learned was that the small signal (preamp/driver) tubes almost always made much more of a difference in sound in the systems I had, than the power tubes. I agree every tube will more than likely change the sound SOME. But the most influence in the designs I have tried seems to be the tubes up front. Anyhow, that's what I learned.