I don’t disagree, I actually had a chance to listen to them a good bit in DC but it’s just the price seems unjustified for the way they sounded. Those PAP Duet 15 with the Voxativ drivers…
The Audiophiliac gave up his trusty long time Cornwalls for them as his new reference. The UL sounded great with the DeVore Super Nine which were a cut above the F&R for the same dollar amount. At this point now that I’ve got a wider range of listening it’s getting harder and harder for me to not take pricing into account.
Also another good pairing would be the Mofi, the new Andrew Jones offering. I’m sure they were at Axpona but you may not have listened to them. The UL is a very capable little integrated, it’s just the fact that you’re limiting yourself with a range of usable non black market kidney priced loudspeakers out there. You’ve mentioned most of the good ones though.
I rolled some of the best 12AU7 (ECC82) tubes but 12AT7s were better which is great because they are cheaper. The Brimar 6060T and Amperex E80CC sounded great.
The RCA 12SN7s were as good as Melz 1578 perforated plates, so I guess you can save some money and stick to 12SN7s. I wanted to try the 12SX7s, haven’t gotten to it yet but everyone seems to love them.
I’m currently using a pair of Miniwatt 18ECC, which I bought from Benjamin at Mojo Audio, because he said that these were his favorite tubes from his LTA modding days. Benjamin said he liked this tube because it had twice the plate area of a 12AU7 or 12AT7, which results in a more effortless sound and more dynamic by comparison.
I have to admit I didn’t really do much back and forth comparisons, because the MZ3 sounded just the way I wanted after putting the 18ECC’s in, so I kept them there.
It is a direct replacement for a E180CC/7062, can be used as a substitute for a 12at7 (but it has less gain than a 12at7), and in most cases can sub for a 12au7.
Judge for yourself but 12SN7’s present a wider stage across the board, both as a pre and amp to my hearing and perception. I also have some Brimar 12AT7 in there that i am extremely pleased with, the funny looking ones with the little plastic plate on the bottom.
I so really adore my LTA MZ3; Flea watts rule! If the First watt sucks, why bother? This is a damned fine single watt of power , I set my expectations, my genre , and then sit back and enjoy. Shout out to Spatial Audio M4 Triode Master , doing more with less.
Looking to get a backup set of tubes for my Ultralinear. The following is from the manual.
12AX7: The 12AX7s should be a matched pair.
12AU7: These are used in the preamp section (the smaller circuit
board) and in the power amp section. In both cases, the 12AU7s
should be matched pairs and each individual tube should have
both of its triode sections matched as well.
Based on that, I’d like to identify what’s there currently so I’m posting pics. Potentially @Hazi59 if you can point me to one of the multiple references you’ve made on tubes in the past if you’ve spoken or described their qualities somewhere. An suggestions on suitable tubes that may lean the sound one way or another based on what I’ve got here. Looking for top shelf recoomendations.
These are a pair of one of the umpteen flavors of Mullard. 12AX7 and they are a matched pair. A lof of the writing is worn off though so can’t even tell what the date code is. They are in the amplifier input section.
The next pair is also in the amplifier input section but they’re 12AU7. It’s also a matching pair and they have green label (perhaps from a 3rd party distributor so not sure of the manufacturer.
The last pair should also be a matched pair based on the manual but the labels don’t match. They are 12AU7 but they are used in the preamp section. Since the preamp board on the UL is vertical, they’re housed in a retaining mechanism with a spring and a an aluminum cylinder that twist locks. So way for them to move or dislodge during transit for sure. On one of the tubes you can see a Eico by Mullard marking. Made in GB.
The date codes on mullards are engraved into the glass, you can often read them, by rubbing some color into the engraved area and wiping it off. Fiddling with lighting until it catches the engraved surface can often help as well.
The only real thing to watch is that some late era tubes have engraved markings that don’t match what’s printed on the tubes, the engraving is ALWAYS correct in this case. As tubes got scarce, some distributors would re-label tubes with different markings for vaguely compatible tubes.
If your buying from a reputable source you shouldn’t run into that, but it’s worth knowing.
I have z40+ integrated w/mullard el34s so this might not be the same for you, but:
In the 12ax7 position I’d recommend Sylvania 5751 3-mica black plates (replaced beloved Amperex long plates foil d-getters!!!) if you don’t mind the slight gain reduction. they sound even better than the amperex tubes to my ears.
In the preamp, I mostly use amperex 7316s - great tubes. i’ve been also trying cheap RCA cleartops side-getters and totally love them - crisp clean detailed top, great warm mids, just ok bass, wide stage. These really work great with the mullards but might be too crisp for your 17JN6s? Worth a try for sure.
I think the phase splitter 12AU7s are the least influential on the sound and you probably don’t need anything special there. hope this helps
This is interesting and to know. That’s where the green labeled CONN ltd tubes are. I think they may be Sylvania but I’m not fluent in the descriptors. Quite the cost difference so definitely will keep that in mind.
That’s great news, I was actually wondering today if it was possible to swap out the 12ax7 in my Ultralinear for a 5751, because I am looking to reduce gain slightly, to give myself a bit more range on the volume knob. And double great news because I’m a big Amperex fan. I have a single 1958 Amperex 12AU7 Long Plate Foil D-Getter in another amp, and was wondering if I wanted to buy a pair of the 12ax7.
But Nicholas at LTA warned me that if I wanted to keep my warranty, I shouldn’t try anything other than exactly the same tube type (e.g. replace a 12ax7 only with another 12ax7) without getting permission, so I’ll double check with him on the 5751. There’s always the chance that the Z40 and UL are different enough that something that works for one doesn’t work for the other.
Didn’t know you had a UL, but if you do, it should have a “high res” feature on the volume control that allows you to switch from either 0 to 99 increments to 0 to 199 increments so you have finer control.
LTA got back to me with some answers on tube rolling with the UL+.
In terms of which tubes make the biggest impact when rolling, they recommend this order:
The two 12AU7/ECC82 in the preamp section.
The two 12AX7/ECC83.
The phase splitters (12AU7) will make the least sonic difference.
They also confirmed that 5751 can be used instead of 12ax7 (which I know we all knew already, but from a warranty perspective, I just want that official seal of approval). They’ve liked using the RCA 3-mica black plate 5751 and the Raytheon “windmill getter” 5751 in the past.
I’m also intrigued by the Sylvania 5751 3-mica black plates that @dvican recommended, given that he and I both like the same Amperex tubes.
@dB_Cooper Your 12au7 with green labels look like Sylvania, because that’s what the 312 code normally means (you can see the vertical 312 139 in the second photo).
I know they’re legit Mullards because they came from LTA, it’s my og set of tubes and they probably wouldn’t bother with nickle and dimeing that way. That said, it’s been pointed out to me that they’re not the “best of the breed” looking with some manufacturing imperfections so there’s room for improvement when I go hunting and I’m much better informed now.
I agree, I wouldn’t expect LTA to nickel & dime, but that’s not what I meant. From what I’ve read (so this is one of those “I read it on the internet” stories, I have no idea of its accuracy), when Philips was contracted to deliver a certain number of tubes for export, and they didn’t have enough tubes from the contracted factory (let’s say Mullard Blackburn), they sometimes used tubes from another factory, but would still label them as Mullard. They would have all been within spec, so it probably wasn’t a big deal.
In any case, assuming they are Mullard, the codes in those links I provided will tell you which Mullard factory they came from, and maybe even which year, in which case you’ll be able to tell if they’re best of breed or not, e.g. a 1962 Mullard tube from Blackburn is considered better than a 1970s Matsushita tube from a Japanese factory using Mullard parts. Anyone who told you they’re not best of breed would have had to do the same research.
A rule of thumb for mullards is anything 40s and early to mid 50s is usually the best of bunch. Better if they were from a UK (blackburn) plant. Late 50s up to '59 are very close to this. Part of '59 to through 60s are when they started diversifying (philips, amperex, same tube and design, different factory and location, etc) still good but they tend to loose some of the real magic.
With most tubes, the earlier production the better. It’s like the manufacturer put their best efforts in for initial runs, then slowly cut a corner or two as the years went on. Ymmv if those slight changes made a difference or is worth the $$$.
I think one of the few that got better is the Amperex 6DJ8 and it’s variants, most because they made stronger and better tubes for airforce use. The late “flawed” pinch waist versions being very rare but supposedly one of the best. The pinched waist was a manufacturing defect but is said to give it tight and exacting detail while not losing the amperex magic.
, I set my expectations, my genre , and then sit back and enjoy. Shout out to Spatial Audio M4 Triode Master 
, doing more with less. 
