The "Venusian' is, as far as I know, the origins of the Lumi. I apparently bought a earlier near proto unit that was hand wired (as if any of them wern't!)
It uses a 40-45kb dual mono solid state PS box, which is fully stuffed. Four transformers, about 5 chokes.
A separate box for the phono section. It is fully stuffed. With boards and binding posts, with "Randall Research" wire. The same wire that was in the original Mod Squad line Drive. It uses 4 5691's, and two 6em7's. It has a second set of RCA jacks to load the given cartridge separately from the stock 47k ohms.
The upper, line stage box uses 2 6SN7's and 2 6DN7's. And a pair of 12AU7's for tape line out buffers. Everything but the volume control is activated as single channels. Two overall 'gain steppers (5 steps) and an overall ladder discrete type 23 step volume control.
Three Chassis total.
It rocks! As you might imagine.
Here comes the painful part: I got mine off Ebay for $106.05. Fuuken A! It was so badly represented, that no-one recognized it. But I'd recognize a Bruce Moore circuit and wiring..anywhere. I knew what it was. Seven sweaty days of waiting later..it was mine. I went looking for 'broken tube amps'..and stumbled across it.
one last point: Scott Frankland (the F in MFA) still works on these, for those who want them modded out properly. |
A question for kana813: do you have any pictures/schematics for Venusian? How was it broken down into three chassis? And BTW, I agree that you have to search hard to find a better phono (or line for that matter) than a Lumi. Recapping with modern colder and more open caps (MIT, InfiniCaps etc.) make a lot of difference too. I tried most everything including Loesch and still stuck with a Lumi. Phono section is a little noisy for MC cartridges but... Thanks, Mark |
Hello fellow audio-nuts. While you have most of the facts right, you've got some of them wrong. There was a preamp from MFA called "Luminescence" (I have two. One early pre-production A and a heavily moded B1), with various versions (A, B, C etc). There was a "Venusian", and an "MC Reference", both of which were NOT Luminescences. Lumi was the only one to my knowledge to use octal base tubes, and was dropped only for the reason of unavailability of inexpensive low-noise octal bases for the phono. MC Reference was actually a hybrid (technically speaking) design with heavy solid state regulation. Very rare and expensive in $5k range for a used one. Venusian I've never heard nor seen but I don't believe it used octal bases, I may be wrong here, but it was definitely not called a "Luminescence Venusian". Thanks for the forum, Mark |
Hi Mike.I would have to concurr with Kana as well.No miniature triode based preamp I have ever heard seems to capture the "soul" of the music quite like a well designed octal tube preamp.I have owned the CAT sig mk2,various versions of Audio Research preamps... from the sp-3a,on up through to the sp-10 mk2,[still in use] the Klimo Merlin as well as the new supratek syrah.ALL of them very highly regarded and while they all make beautiful music.....the Lumi is still "THE reference" in my rig[phono only].Of all the above mentioned preamps-the Klimo Merlin was the closest overall to the Lumi through the phono stage and I want to point out that my observations are based on the phono stage ONLY.Cheers |
Great technical informations from everyone, thanks to all.
I'm considering purchasing a new preamp that I'm familier with, and the ones that I've heard and liked are: Hovland HP-100 and MFA MC Reference.
Since I'm a big analog guy(4,000 lps and counting...)MC Reference is my first choice due to the great phone/line stage it has(as you all mentioned) and can be modified/repaired easily locally.
But on the other hand Hovland has more of the modern appeal with pretty good phone stage of its own and is quite affortable on this site(around $4K).
Decisions, decisions........
|
Ecclectique- it shouldn't be surprising that the Syrah using 6SN7s in a transformer coupled line stage is less demanding on tube quality. The 6SN7 has less gain than
6SL7/5691 used in the phono section of the Lumi.
The best tubes I found for the Luminescence phone/line sections were the brown base RCA 5691/5692s.
Good luck with your Koetsu |
Hello Mike. As an owner of a luminenscence, a few things should be addressed if you are thinking of acquiring one.First:If your system is biased toward vinyl; as mine is,retubing becomes a very important issue as the currently made octal based tubes are a total waste of time sonically in the Lumi, acquiring quiet nos 6sn7's and 6dn7's are not only a very expensive investment but a giant crap-shoot at best.The Lumi is extremely critical to the tubes used "especially" the 6sn7's.That particular type of tube is very very prone to microphonics,so much so that more than half of them are unacceptable in the Lumi.I have another preamp[the supratek syrah] and two amplifiers that employ the 6sn7 and most of my nos tube stash sound terrific in the syrah, whereby when used in phono stage of the Lumi...they just don't cut it. The syrah uses the 6sn7 for gain in the line stage only and the amps mentioned above employ it only as a driver stage for an 845 triode.Phono gain is another animal altogether as noise becomes paramount when driving low output moving coils!Re-tubing can become a very frustrating experience.The highly regarded Kenrad black glass vt231...while it is my tube of choice in the syrah,does not seem to like the lumi!The early 50's Sylvania gt versions sound fabulous in the lumi and mediocre in the Syrah.Go figure? That being said:When optimized with low noise tubes-- I personally believe the lumi to be one of the finest preamps ever made and one that can compete with ANYTHING out there, regardless of price.As TWL mentioned,when updated with caps,gain pots and a few reistors here and there, it then becomes next to impossible to beat.Further more... its circuit topology is a very straight-forward and lends itself to updating its passive parts- the circuit does not use any boards and is all wired point to point with lots of room in the chassis for changing caps or any other passive parts.I am currently using a shelter 501mc and I can honestly say that the 501 sounds more organic through the Lumi and potrays a larger volume of space on the stage than the Syrah.I am anxiously waiting for the return of a Koetsu rosewood that I have sent to Japan for a rebuild. I am speculating here, but I believe that the lower the output of the cartridge,the more difficult it will become to optimise the preamp. Hope this Helps! Cheers David |
MFA Luminescence MC Reference preamp is not an octal base
preamp.
The last of the octals was the Luminescence C, which was built in Dec. 1990.
MFA Luminescence MC Reference used 6DJ8/6922 tubes. I never
heard this model, but I think it was review in TAS.
I owned three different models of the octal Lumincence including the three chassis Venusian.
Phono section uses 4-5691; 2-6EM7 for 44 db of gain.
Line section uses 2-6SN7(5692); 2-6DN7 for 28 db of gain.
If you're look for an octal Luminescence, try to find a
two chassis version with a tube regulated power supply.
If you're into LPs, the octal Luminescence is highly recommend for it's superior focus,air and spatial qualities. No nine pin triode based preamp, I've heard
comes close. |
It is an excellent preamp, highly regarded, and a classic. Of course, it is an older model, and would need some re-capping and such, to be what it was intended, and some mods have been found for improvement. They are fairly rare, and command high prices. It is all tube, including the separate power supply. The phono section is a very good one, as are all of Bruce Moore's phono sections. You can do better with some newer products, but the Luminscence will still be pretty close to them. And better than most of the newer stuff. If you can find one, they are probably one of the better choices in a classic unit. I currently use a MFA Magus, which was the lower cost unit made in the same era. It is not as good as a Luminescence, but still quite good, and excellent value for the money. I've had mine re-capped, re-wired,re-jacked, and new pots. It sounds real good. I'd still rather have an Aesthetix IO. |
