Its a great site guy has many many old stock tubes and mentions
Since you have amplifiers that respond very well to tube rolling its a must read
I actually had the same speakers Joe used and his recommendations Spot on
Enjoy!
Looking for advise regarding Rogue M180’s
Last week a friend gifted me a pair of Rogue M180’s. They were sold as 180’s and I received them from the original owner. Im guessing them to be 10-12 years old. They were used when first purchased for about 5 years sparingly. Since then they have resided on a flat dolly in a spare bedroom. The amps still have the original Phillips ECG 5751 and 5814A’s installed. The original EH KT 90’s are loose in a box with an octet of low hour Gold Lion KT-77’s . Years back when in use the owner contacted Rogue and stated they were too powerful for his room size and speaker selection. Rogue responded by recommending the GL KT77’s and suggesting that he could also lower the bias from 40ma to 30ma. I was provided the supporting emails dated September 2019. Here is my situation followed by my questions. I currently have a low power single ended system with Zu speakers. Second, the owner stated one might have a hum, but was not sure. He’s on his second complete system since and has a room full of gear he’s lost interest in and his memory is vague. Also back then he had power issues with his provider and stated they installed a new transformer on the street. So my questions are first, checking for any hum. My intent is to take a single amp and connect one JBL 4312 to it. Install the KT77’s, plug it in and listen for a hum and bias the tubes. Do I need the input open or shorted ? Or something else ? Second, the 12AX7’s being replaced by the 5751. I see there’s a mu of 70 Vs 100 with the 12AX7. Does that effect the overall output power of the amp or just change tone and distortion? FWIT I have 6-7 pairs of NOS Telefunken 12AU7’s but zero 12AX7’s. My intent is to check for hum without causing any damage. If a hum exists, I’ll ship to Rogue. In the short term if I’m successful, I’ll test drive with my existing Rogue RP-1, the JBL 4312A’s that are mint and the 26” Sound Anchor stands I have with them. And I’d like to get some Telefunkens to put in the 12AX7 positions. After that, there’s a pristine Rogue Hera that’s been inspected and re tubed by Rogue that I’ll ask to purchase before I start looking for speakers worthy of the pairing. Also I emailed Rogue for support a week ago and have not received a response. Thanks in advance for any feedback and my apologies for grammatical spaghetti, but I’m limited to an IPhone. Cheers , Mike B.
- ...
- 69 posts total
The 12AX7 and 12AU7 slots have different roles and operational parameters. You would sub 5751, as a near-12AX7 equivalent, into the 12AX7 slot, NOT the 12AU7 slots. A 12AX7 (or 5751) is gong to struggle like crazy in 12AU7 slots, diving those big KT120 or KT88. You'll get higher distortion for sure. You won't hurt anything by experimenting in these slots, but best to stick to tubes with lower Rp (i.e. they can push more current) in those 12AU7 slots. Hell, even 12AU7 may be underpowered for this slot, which is perhaps why some of us report good results with 12BH7 sub. Many good 12AU7 subs have already been listed here. The 12AX7 (phase inverter / splitter) slot - you can experiment a bit more here. Besides 5751, 12AT7 and 12AY7 should be OK here. I've actually used 12AY7; it can sound pretty good (GE red "industrial" label 1964). I even once accidentally put 5814 (a 12AU7 sub) into the 12AX7 slots and it sounded decidedly fatter / colored, but also pretty euphonic. Took me a day to notice my error lol. The GE triple-mica black-plates (a.k.a. TMBP) 5751 are awesome tubes. Great choice! Very sweet sounding, but with great sparkle, dynamics, and detail. Fantastic mids. There's a special variant of it only produced in 1953 and 1954 which has "silver clips" crimping the little plate "ears" that poke through the mica wafters. I think these sound even sweeter than other TM BP's - but they're rare. And hard to spot from most photos. I've even mixed one of these with a non-clips version (the pair was electrically matched) and it carried most of the "silver clips" magic without causing a notable imbalance. Tubes are generally more flexible and forgiving than you might realize at first :) |
Gentlemen, again thank you for spoon feeding me. About 2 days after the amps came back, I pulled the 4 JJ 12AU7’s and threw in a quad of Seimens nickel plates. I have a quad of Tekefunken G-73 R’s yet to try. Unfortunately my RCA’s and Mullards , I’ve only 1 pair of each. I’m looking forward to trying the GE 5751’s when they arrive this week. I spent an hour reading Joes Tube Lore regarding 12AX7’s , very interesting. I have a couple caveats in my initial tube rolling. First the equipment lacks a proper set up as it’s all on the dining room table. Second I’m trying to like a pair of speakers that aren’t that good. But I’m getting some run in time and can get a partial idea of the SQ I’m striving for. I’m definitely being guided by the experience being shared. I’m coming to the conclusion that I want a larger speaker that’s “ MUSICAL “, that I can crank up and listen to while sometimes moving around. Being extremely price driven , I’m interested in the Tannoy’s , Fyne, MoFi 888, Cornwall IV’s ( not a fan of horns ), Tekton Moab. Unfortunately I’ve never heard any of these. Upscale Audio is about 3-4 hour drive from me. After I get this gear in a proper set up , and some balanced cables , I’ll schedule an appointment to audition some speakers. Also any recommendations for some balanced IC’s that a poor guy can afford, I’m all ears. I’m thinking a 1 meter pair for DAC to pre, and 2 meters from pre to amps. Please keep it coming! Regards, Mike B. |
That’s my leaning too - I love Tannoy DC’s for their mix of coherence, refinement, and detail. Haven’t heard Fynes; they can be viewed as a continuation of Tannoy, but losing of some of the old-world / traditional features of Tannoy Prestige along the way (alnico magnets, textile surrounds). There’s a WIDE range of sounds you’ll get from various Tannoy models (and probably Fynes too). If you want a BIG sound then that is (perhaps obviously) best manifested by the models with a 15" DC driver. The 12" DC can get close. But when you step down to a 10" DC, it’s a different beast - they sound GREAT in midrange, but they’re not gonna sound "big". With smaller DC drivers you’re either going to want to supplement with subs OR at least look for models that add a dedicated woofer to the main DC driver (as Fyne does with 702, 703, 704 lines like Tannoy used to do with Definition DC10, DC8 before them - and further back, D700 etc). There’s been much talk about the closure of Tannoy’s Scotland factory, and move to Music Tribe’s Chinese factory, since Behringer’s acquisition. Yes, even all Prestige drivers are now made in China! However, being curious, I finally bought a pair of loose Kensington GR drivers made in China - and plugged them into a definitely made-in-UK Kensington GR black edition. Frankly, I think these Chinese drivers sound better than UK - maybe not a fair comparison if the "black edition" drivers were tweaked differently. But the Chinese do sound better. And if you ignore sticker labels (and gold vs. silver metal colors), they look to be of exactly the same quality build - you would not be able to tell which is which!. |
- 69 posts total