#2131
|
|||
|
|||
My favorite thus far: 6L6GC / 5V4G / 6DJ8.
Specific favorites:
Zenith 6V6G (vintage) Rectifiers that I’ve tried: 5Y3, 5U4, 5U4GB, 5V4, 5V4GA, 5AR4 (multiple manufacturers of each). Front-end (9 pin miniature socket) tubes that I’ve tried: 6CG7, 6N1P-EB, 6DJ8, 6N2P-EV, E88CC. I probably should have bought “socket savers” – because according to my notes I’ve conducted 90 tests. I think I’m done tube-rolling for a while. The good news, I’m very pleased with sound quality. My system where the Inspire amp is installed:
|
#2132
|
|||
|
|||
Robert_KC, your Inspire amp uses 6DJ8 as the driver tube? My Inspire SE EL84 does, but I hadn't seen any of his KT88 amps use that tube. Wouldn't mind it if mine did, as I have several very nice Amperex 6DJ8-types.
|
#2133
|
|||
|
|||
Quote:
GT6L6 GE with the JJ5AR4 along with the 6DJ8 is a great combo. If you were to go to a vintage 6L6G coke bottle shape tube you would want to use a 5Y3 rectifier tube. Other 6L6 vintage NOS best suited with a 5U4 rectifier. The 5AR4 is AOK with any of the larger tubes like the KT88, 6550, KT90, KT120 and KT150.I think it is interesting that while my amp has the 9 pin miniature input tube socket, he is now making then with 8 pin octal socket (e.g., 6SN7). Does anyone know if there is a reason? I just checked – he has a KT88 amp listed now … Last edited by robert_kc; 08-27-2016 at 11:36 PM. |
#2134
|
|||
|
|||
Quote:
This is interesting, since your amp came supplied with a 6CG7, which is a 6SN7 in a 9-pin bottle. His implication that they would be biased differently puzzles me. I do know his KT88 amp is now $45 more expensive, and that may reflect a higher parts cost. It also appears that as his amps (and preamps) are becoming more popular he is going a little more upmarket. IIRC, Inspire started as a kitchen table retirement hobby business, originally revamping Magnavox console amps and later producing his own adaptation of the circuit. His metalwork has improved and he now uses higher end passive components. Both Cary Audio and AES exclusively used octal tubes, at least I don't recall seeing 9-pin tubes except as the output buffer in the PH-1 phono stage. It could be that he's switching based on the higher perceived quality of the octal tubes. That being said, there appear to be a lot more options for affordable tube-rolling with 6SN7's. 6CG7's weren't made by many manufacturers and the best 6DJ8 types have gotten expensive (and frankly was not even designed as an audio tube to begin with). It seems like it is harder to find a good sounding 6DJ8 than a good sounding 6SN7. 6CG7's are electrically identical to 6SN7's but with the elements closer together in the smaller bottle there are potential compromises. When I saw Dennis had moved to a 6SN7 right after I bought my amp I was disappointed. My options are to use what I have (and am currently happy with), preferably with a 6CG7, send it back to him to get converted to an octal socket, sell it (I have a number of amps), or buy a socket adapter to use a 6SN7. I may do the last anyway just to see how things sound. |
#2135
|
|||
|
|||
I spoke to a very experienced tube amp builder and asked about subbing a 6SN7 for a 6DJ8 using an adapter and he told me it would be a terrible substitution. That the two tubes were electrically quite different and it could significantly alter the sound. A circuit designed for one would be ill served with the other. It is worse in the other direction, as the 6SN7 circuit could have much more voltage than a 6DJ8 can handle.
Last edited by Bombadil; 08-28-2016 at 01:05 AM. |
#2136
|
|||
|
|||
Over on another forum, Jim McShane differs:
"Slow down! Relax, deep breaths... The only difference is pin 9, which in a 6CG7 and a 6DJ8 are both connected to an internal shield in the tube. In a 6FQ7 pin 9 is not connected, so the basing is not an issue at all. No rewiring is needed. The biggest potential problem relates to plate voltage limits, 130 on the 6DJ8 vs. 330 on a 6CG7/6FQ7 (source - GE Essential Characteristics). Depending on the circuit, the plate may not see a real high voltage. Keep in mind also that the 130 volt spec was the "Design-Center" spec., the most conservative of the three rating sytems used for tube specs. If it were rated using the "Absolute-Maximum" spec., it would be rated considerably higher in all likelihood. I'd prefer the 6CG7/6FQ7, but YMMV." |
#2137
|
|||
|
|||
Quote:
|
#2138
|
|||
|
|||
Has anyone upgraded their amps or preamps from Dennis. I am currious about sending in my LP-2 w/ DACT to be upgraded to the LP-3. Anybody gone for this option? I would be worried that some of the magic might be lost....
|
#2139
|
|||
|
|||
Is the LP-3 an octal version of the LP-27a, or is the circuit different? I understand that the LP-3 has three 6SN7/6SL7 tubes. However the 6**7 types are double triodes, where the 27/56 tubes in the LP-27a are single triodes. Is Dennis simply running 1/2 of two of the tubes?
|
#2140
|
||||
|
||||
I had Dennis upgrade my older lip-2 with 6dj8s in front and a 6cg7 in back. He said I would see a noticeable improvement. He was right. I do not think you will be disappointed. I have ultimately settled back to the same tube complement I was running prior after shuffling in 6cg7s everywhere and different 6922 variations as well. That is volshod 6h1n eb output tubes, GE 6cg7 driver and Sophia 274b rectifier. A fantastic sounding preamp.
|
Thread Tools | |
Display Modes | |
|
|
Audio Aficionado Sponsors | |