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Anybody got any experience with these? A buddy of mine that has a Primaluna D5 was asking me about the JJ 6550's and how they sounded. I don't use traditional power tubes, so no idea how to answer him. A quick search here turned up nothing either. He's using GL KT88's so not sure, based on what I've been reading here, that he can do any better, but thought I'd ask if anybody had anything to say about the JJ's. BTW, I have a Primaluna CD player that uses the same 12AU7/12AX7 small signal combo that many of Primaluna's other machines use, including the D5. Anyway, I found a very synergistic combo that seems to work well - at least for me. An RFT 12AU7 and a JJ 5751. Makes for a very nice combo.
Follow Ups:
The JJ power tubes I have recently purchased are very good.
I just ordered some of their premium 6922's today. Always liked their 6922' but had trouble with them staying quiet. Been so happy with their 12v tubes lately that I decided to give the 6922 another chance. I REALLY hope they've turned the quality corner. Encouraged by what folks have been saying about their power tubes here.
I only have experience with the JJ 6550 in a guitar amp, the Fender Bassman AA864, modded to accommodate.
I found it sounded good as 6550's go - lows are like that of a big 6L6GC, as expected, it has a warm but articulate manner, and the highs remain under control. When overdriven, that warm character is pretty sweet. I'm not sure it would best a GL KT88 for hifi, but if you money to burn and like to roll tubes, it's not a terrible tube to consider.
Note: the Bassman runs these tubes at about 450V-ish B+ to the plates and screens. My experience with JJ is that they don't respond well to anything running above 475-500V, except their KT88. A VERY well selected sextet JJ KT88, I can personally attest, withstood the Fender 400PS - 700V at the plates, and 350V at the screens, running 125W-ish to the pair in AB2.
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May your tubes be warm, long-lasting, and always lively. Holy be thy heater.
Thank you for that. Just the kind of feedback I was looking for.
What amp are you going to run them in?
Prima Luna...my bad.
JJ has very nice sounding tubes and I can't take that away from them however,until I see evidence that they have improved their octal base tubes for reliability,and I mean in dramatic fashion,I just don't feel comfortable recommending them.I do know that McIntosh is using JJ tubes as original equipment for the KT88s in the MC275.This shocks me for the simple fact that the original MC275 used Genelex KT88s..Being they wanted to replicate the original MC275 in most every way possible,this didn't make much sense.
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
Edits: 02/16/15
The JJ KT88's as supplied by Mike Sanders in my Quicksilver Silver 88 monos have proven very reliable and good sounding.
I know that Mike tests every tube and runs in every amp.
I have also seen (in person) how McIntosh tests every output tube. They were distressed when Svetlana (the manufacturer, not the brand) stopped production in St. Petersburg,
It's possible that the JJ 6550's are very good tubes indeed.
Agree that testing procedures is key here. I too have QS amps equiped with JJ kt88s and they have been nothing but spectacular in sound and quality for years now. Whatever Mike does to these guys in terms of screening and burn in is really really special. Too bad the manufacture got so far away from QC in years past. Good to hear they are coming back around with better product, if that is truly the case.
Edits: 02/17/15
Bill
There is no denying the wonderful sound quality of JJ tubes. Jim McShane even knows that.As long as they corrected the issues with their octal based tubes,I'm all for giving them another chance.
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
Hi Sam
Good to hear from you.I love your reviews..It makes me wonder if the US is getting different JJ octal tubes than other countries.The reason I ask this is, I don't hear about these issues in other countries.AAMOF,when I first started getting the JJ KT77s about 8 years ago,I called up Tomas at JJ and I told him about many of the tubes having crooked bottles,under sized pins,and flashing in the wrong places..He wasn't even aware of these issues and that made me wonder if the US distributor was buying B stock or factory rejects..Jim McShane is one of the most reputable tube dealers on this earth and he also had so many bad JJ octals that he wouldn't chance carrying them..The 6BQ5s,the 9 pin miniatures,and 300b and 2A3 tubes are all up to the minute..I even have a quad of Groove tubes JJ KT88s with less than 200 hours on them two of them have shorts and one has flashing over 85% of the tube along with a ring getter that fell off inside.
If they genuinely rectified those issues from before,I would be more than happy to give them another try.I do love the sound of JJ tubes.
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
Edits: 02/16/15
I thought the new Telefunken Black Diamond lineup was the answer to that question. So, I searched a little.
On the Tube Depot site, it states "The TELEFUNKEN EL34-TK has been designed to handle a slightly higher grid voltage than the traditional EL34." I got into looking for close up photos of the glass. The grid posts have been changed. There seem to be physical differences worth considering O.o
Photo of the EL34-TK
http://www.telefunken-elektroakustik.com/images/tubes/black-diamond/el34-tk-tube-box.jpg
Photo of the JJ E34L/EL34
http://amp8.com/etc/amp-inho/jpeg/vvinfo-1.jpg
Photo of the JJ 5550
http://www.thetubestore.com/JJ-6550-Audio-Vacuum-Tube-Image.jpg
Photo of the 6550-TK
http://cdn1.bigcommerce.com/server1200/b633e/products/7848/images/24267/16550tk__79386.1406938395.1200.1200.jpg
So, while it doesn't answer your question, I have opened new ones!
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May your tubes be warm, long-lasting, and always lively. Holy be thy heater.
It could be possible that the US distributor got some bad JJ stock. I've been using all kinds of JJ tubes for years, and have seldom had any issues although there were a few minor ones with ECC82's and 3's. Power tubes have not been an issue.
In fact I've had far more problems with the much acclaimed Gold Lion KT88's than I have with JJ. I have to admit though, I've never tried a JJ 6550.
Dan Santoni
Thanks, Mike. I'm aware their rep for octals had been bad in the past. They've really stepped up their game with their nine-pin offerings. Maybe their power tubes have gotten better since the dark days. Hard to know cause I just don't hear people mentioning them. Not for quite a while anyway. Interesting that Mc uses them. Wonder what kind of reject rate they get on them?
JJ 6550 works fine in europe.I have 4 of them in my vta since 18 months,they
still hols bias and still sound good.
Note that the metal base is no more on jj6550, they are only on the tfk-branded ones. jj6550 has a black base,like the 6l6.
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