Best KT88 for MC275V

For my new MC275V I bought the Shuguang Treasure Series Vacuum Tubes KT88-Z, GEC KT88's 1970, and Tung Sol 6550WC 66-22 Short bottle, all new never used. So far I'm in Neils camp the Mazda 12ax7s and Gec A2900 have made the most sonic difference so far, However none of these power tubes have more than 20 hours on them. I also tried Raytheon 5751 windmills, 58 LP Foil BB's, and Selected smooth Tel's, Mullard 10m's, and Siemens MC6 1958 LP. For the AT7 I've used the Valvo Pinched waist Blue VGO d9g, Seimens e81CC, Tel 801Ulm. I believe I could mix these 12V's around and confuse anyone as to what power tubes they were listening to. The Invitation is open to anyone.
MPLS, MN.

The Pre-Amp is a Restored ARC SP3 w/ 8 matched Tele Rib Plates 1963
Wadia 170i Great Northern Sound Upgrade
BenchMark USB dac1( can feed balanced right into the MC275V)
All Transparent Musiclink Ultra interconnects and speaker cables
 
For my new MC275V I bought the Shuguang Treasure Series Vacuum Tubes KT88-Z, GEC KT88's 1970, and Tung Sol 6550WC 66-22 Short bottle, all new never used. So far I'm in Neils camp the Mazda 12ax7s and Gec A2900 have made the most sonic difference so far, However none of these power tubes have more than 20 hours on them. I also tried Raytheon 5751 windmills, 58 LP Foil BB's, and Selected smooth Tel's, Mullard 10m's, and Siemens MC6 1958 LP. For the AT7 I've used the Valvo Pinched waist Blue VGO d9g, Seimens e81CC, Tel 801Ulm. I believe I could mix these 12V's around and confuse anyone as to what power tubes they were listening to. The Invitation is open to anyone. MPLS, MN. The Pre-Amp is a Restored ARC SP3 w/ 8 matched Tele Rib Plates 1963
Wadia 170i Great Northern Sound Upgrade BenchMark USB dac1( can feed balanced right into the MC275V) All Transparent Musiclink Ultra interconnects and speaker cables
I'm very curious about your reaction to the Shuguang KT88Z's; particularly bass power and bass transients. Those A2900's are really something, aren't they? I think they could push more performance out of almost any power tube. I notice you haven't tried the TMBP Sylvania or RCA 5751's. Would you like to try a pair?

Neil
 
I'm a Mc275ce newb, I've gotten Telefunken 12at7s for the "t slots", Rca 7025s for the "x slots" and now need power tubes. My budget allows $200 for 4. The amp is a 275 commemorative edition hence 275ce. Consider my amp, budget and the tubes I now have in place......should I pull the trigger on; Penta kt88sc, or GL re-issues? thanks
 
Last edited:
I "think" I prefer the GL re-issues over the stock tubes. However I use the word "think" because by the time you power down the amp, swap the tubes, power up, and replay the same music selection, your memory has already forgotten what the old tubes sounded like. It's not night and day.

I would like to know if anyone here has run 2 fully warmed up MC275s side by side with the same speakers and different tubes and compared the results.

I thought tube rolling was fun and then I decided that it was annoying so I am just sticking with the tube combo I have as it just sounds good!
 
I did put in the 63 Raytheon TMBP Windmill getter for a time. These were really nice, The GE JG 5751WA is also worth mentioning. I have many Syls that came from Mil. surplus 3mica black plate 50's and 60's put into individual tube cans in the 70's can't follow the logic but that's what the labels say. Also have the standard and gold pin 5751 Gold Brand, don't get what folks are talking about with these. The tubes you haven't asked about, but are real sleepers, are the CBS Hytron / LEEDS & Northrup label 7729 and 7728 (I also have Raytheon versions) these were made for broadcasting and carry the reg instrument labels. Like the under rated RCA Command Series 5751, these are very detailed, but have a warmer side to them that doesn't lead to listening fatigue.
 
I actually preferred the RCA 5751 to the Sylvanias as well. I agree with Neil in that the small signal tubes will have the biggest effect on sonics, esp the 12ax7a slots. Another sleeper tube is the RCA 6201 Black Plates. These can be found NOS for about $15.
 
Maybe a stupid question...

...but would the comments and opinions hold true for a pair of MC-75's also?

I have a nice set of Arkay made in GB 12AT7's that I just obtained that I want to sub in and see how that goes. However, my MC-75's were put on the shelf to make room for the Christmas tree, and haven't been set back up yet....:no:

Now that I'm back in town, I foresee that happening shortly....:thmbsp:
 
Post #43 The Penta KT88SC and Reissue GL's are very close in sound and in price. The SC's are (at least visually) exact replicas of the original Genalex Gold Lions. The reissue GL's construction are nothing like the originals, no matter New Sensor's claims about reverse-engineering, blah, blah! If those are your two choices, I'd go for the GL's just because they're easier to resell :yes: Best matching, price, and free shipping on those two is from www.dougstubes.com. In that price range however, my recommendation would be the S.E.D. KT88's (McIntosh's current OEM KT88) for $170 per super well-matched quad from Gene at www.conusaudio.com Additional tip when buying matched tubes: If you need a matched pair, buy a matching triplet. If you need two matched pair (or a matched quad) buy five matched tubes -- this way, if one of the tubes in use ever goes, you'll have an instant matching replacement! If you're feeling really anal, you can rotate them like pre-radial car tires :D

Post #44 It's nice when you can do instant side-by-side comparisons, but it's also possible to A--B with a short interval of time in between if:
A. You decide beforehand what you want to listen for. With power tubes for instance, bass power, transient accuracy (control/tightness), and low frequency extension (how low does it go!?) Remember to keep everything apples2apples -- levels, source material, etc. A handy feature if your CDP has it, is the 'Repeat' function applied to just a short segment of music. You'll be amazed how much detail your brain 'remembers' when it hears just a small segment of something over and over. Is that what Ravel was trying to tell us when he wrote Bolero? :scratch2:
B. Take notes as you're listening! Be wordy and describe to yourself what you THINK you're hearing in as many ways as you can. Refer to your notes from "A" when you are listening to "B". Make categories for each session (in the case of power tubes for instance -- power, transients, LF extension.) Use a pencil and paper!! One reason many (TOO many) audiophiles aren't getting the satisfaction out of their systems they might, is simply because they haven't taught themselves how to listen -- that repeat function on your CD player is one of the BEST teaching aids in audio (you see, there really IS a "purpose for everything under Heaven", even the digital format :thmbsp:) It also helps (but not absolutely mandatory) to decide beforehand what you're going to listen for! Whatever is especially good (or bad) in a short segment of music or vocals will just pop right out at you!! So many audiophiles DON'T REALLY LISTEN!! It's not hard -- you just have to remember to do it! Listen to a Mozart piano concerto or symphony and try following the instuments that are NOT playing the main melody, but underneath it -- that's a really great listening exercise!

Post #45 John, I'm not doubting you, but this is the first I've heard mention of a Raytheon 5751 BP/WMG with three micas. The three mica Raytheon black plate 5751's I've run across always had regular wire getters. Are you sure? RE The 50's/60's Syl in 70's cans: they are from one of the Scandinavian countries' Air Force (Sweden, I think) which "juiced" their spare tubes (new OR used) once a year (gave them a jolt of voltage) to check them and keep them up to specs. The date on the can is when that was last done. The Syl TM 5751's with gold pins ALL have gray plates. And they don't sound anything like the black plates (which NEVER have gold pins :no:) I never tried 7728/7729's. I'd like to if they're not too expensive? Are these direct subs (same specs) as 12AX7/5751's? Never auditioned the RCA 5751 Command Series (DMBP?) going instead directly for the triple micas. How do you compare the two?

Post #46 In the MC275, the V-2 and V-5 are the tubes responsible for amplifying THE SIGNAL which then goes to the 12AT7's and enables them to regulate (drive) the KT88's grids for delivering power to the speakers. If you think about this carefully, you'll realize that the "amplifying" aspect of a power amplifier occurs in the (little) "gain" stage tubes, not in the power tubes! That's why the 12AX7 #2 and #5 (in the MC275 that is!) have so much influence on sonics. Also true in the MC75, but they only have one gain stage tube per unit.
 
What got you off the Pentas, it was not so long ago that THEY were the cats pj's. Any who, who makes the SED 88, and why are they now the choice. I'm trying to upgrade from Sovtek 6550s in a 275ce :yes::thumbsdn::no::thmbsp:.....:smoke:
 
What got you off the Pentas, it was not so long ago that THEY were the cats pj's. Any who, who makes the SED 88, and why are they now the choice. I'm trying to upgrade from Sovtek 6550s in a 275ce :yes::thumbsdn::no::thmbsp:.....:smoke:
Nothing wrong with the Pentas :no: I think they're a good value; just that the New Sensor GL's seem to sell quicker on the used market if you need to get rid of them, that's all.

Sovtek 6550's suck and have since way back when ARC used them for their OEM power tube. They eventually learned their lesson and switched to S.E.D.'s. The S.E.D. (the REAL Svetlana) are stronger than all the Pentas and reissue GL's I've measured, and I'm really glad to see McIntosh is using them now.
 
Schweeet, can the power tubes cause the problem that I have described in the "Deep Space 275" thread, and/or would they be a likely culprit. :scratch2:
 
EAT ! The best dynamics and resolution.Expensive,quite true,but the best.Don't hesitate if you can afford them.
 
Post #46 In the MC275, the V-2 and V-5 are the tubes responsible for amplifying THE SIGNAL which then goes to the 12AT7's and enables them to regulate (drive) the KT88's grids for delivering power to the speakers. If you think about this carefully, you'll realize that the "amplifying" aspect of a power amplifier occurs in the (little) "gain" stage tubes, not in the power tubes! That's why the 12AX7 #2 and #5 (in the MC275 that is!) have so much influence on sonics. Also true in the MC75, but they only have one gain stage tube per unit.

I agree. The 12AX7 tubes determine the sonic qualities of the amp. I have been using RCA 12AX7/5751 JRC tubes in my MC-275 IV amp for the past 12 months and must say, these are the best 12AX7 tubes I have experienced to date. However, I have just placed a set of Full Music 12AX7's into my MC-275. Will see how that all goes.

Butch
 
EAT ! The best dynamics and resolution.Expensive,quite true,but the best.Don't hesitate if you can afford them.

I recently replaced ALL my equipment from the Katrina flood. Having spent $10,000 (alot for me) I am a little "ify" on spending much more on tubes that may not actually be my amps problem. So I am going to spend apprx $200 on power tubes (as I have already gotten teles for the "T" slots and RCA 7025s for the "X" slots) in the hopes of getting the amp to perform before I have no choice but to send it to a pro repair facility. (See my other predicament in the "Deep Space 275" thread). :banana::scratch2::tears::no::tresbon:....:smoke:
 
Last edited:
Well, I am running a matched quad KT 88 E.A.T. Diamond tubes on my MC 275 MKIV since a month and it is like upgrading to a 10000 $ amp. Before I had Philips, Gold Lions, G.E.C's and those E.A.T blown them all away.
Now my MC 275 is the best amp I ever heard. Gives bass and dynamics to my Quads ESL 57 that's hard to believe...:banana:

Good to hear the EAT tubes are working for you. They also worked wonders for my in my 2301's. The best tube purchase I made and everyone told me not to buy them. The only tube that I think improved and didn't seem to mess up timing and dynamics but improve it. which is sometimes what I found in tube rolling it maybe fixes a sound and or suits your ear at first but then it causes other problems that you end up noticing after a while and listening to different styles of music. Siemens ecc801s work well in the 275's.
 
for my new mc275v i bought the shuguang treasure series vacuum tubes kt88-z, gec kt88's 1970, and tung sol 6550wc 66-22 short bottle, all new never used. So far i'm in neils camp the mazda 12ax7s and gec a2900 have made the most sonic difference so far, however none of these power tubes have more than 20 hours on them. I also tried raytheon 5751 windmills, 58 lp foil bb's, and selected smooth tel's, mullard 10m's, and siemens mc6 1958 lp. For the at7 i've used the valvo pinched waist blue vgo d9g, seimens e81cc, tel 801ulm. i believe i could mix these 12v's around and confuse anyone as to what power tubes they were listening to. The invitation is open to anyone.
Mpls, mn.

Ha! :D :D :thmbsp:
 
The new Gold Lion KT88 showed up today, two matched pairs.

These are supposed to be new but the values on the boxes are quite a bit lower than what I can find here and elsewhere online when people measure new GL tubes.

Ip; Gm
47; 5100
49; 5200

29; 4100
29; 4000

Thoughts?
 
I had a pair of consecutive 275's and MC 60's. We also had one 275 at the radio Station, and with all of them we used Gold lion KT 88's. I checked my amps every other year alternating with Mac clinics. I ended up with New tubes from Davie and kept the old ones that could still be used in a pinch. My main problem were the miniature tubes. One or two had to be replaced every year. Fortunately the Radio Station bought tubes by the gross it seemed so I could get my tubes at way below retail. I think we used GE tubes for the 240's and 6550's with the Dynakit MK III to save money back in the 60's. The 275 was sort of a show piece.


We had a radio DJ that was famous around town who had portable discos and he used two 275's with each system for the main speakers and a 240 for his monitors. He used Gold Lions too. He didn't like the sound of 2105s, but liked the power so doubled up his 275's wiring them mono. When he saw 3500's he was really impressed, but their size a weight kept him from purchasing them. It wasn't the money he said. Using 275's in portable applications really increased his tube usage. over my pair at home. I actually put more hours on my 275's at home than he did with his portable systems. We would check his amps once a month and he was always replacing a tube here or there.
 
Last edited:
Back
Top Bottom