@decooney Hi , thanks for your input and I did receive the cc. The M-180’s currently have GL KT-77’s. I borrowed a tube tester and they are so low it advised replace on all eight. I tested the original KT-90’s and they are at about 80%, but one is dead. I tried the GL and JJ KT-77’s in my Had. I like the GL’s. My concern is how much bass they will make. I really didn’t plan on using the ZU’s but with KT’77’s could be pretty interesting. I’m hoping to be happy with the JBL’s, but they’re not a long term speaker. Im hoping to get a big wide sound that I can shake the house and annoy the neighbors. I’ll relive my youth and then look for something more refined. Those big Tannoy’s interest me but I guess I’ll have to go to Upscale to audition them. So keep it coming gentlemen and I’ll post my updates. Regards Mike B.
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.
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To @buellrider97 I just read the specs of the 4312A, https://jblpro.com/en-US/site_elements/4312a-information Apologize, I missed which speaker you would use above with the Rogue amp, and assumed you were using the efficient ZUs, and flew right by the 4312A part, doh! While I like the KT77s for lower power amp usage and the idea of efficient speakers used with them, and reading your comment about "shake the house and annoy the neighbors" to "relieve the youth phase", LOL, I'd probably flip-flop on my comments above and agree to have Rouge set and check with Tung Sol KT120s then. My own KT120s can sound smooth playing with bias a little and using the right interconnects with sources and such, fwiw. |
@decooney , No problem, I overlook the fine print often. The 4312’s are a true studio monitor which is not a forgiving speaker. The specks JBL gives are way to low for power requirements. They are happy at a minimum 200 wpc solid state. I was considering Quicksilver before I went low power and Mike Sanders stated they need 100 wpc with tubes. At the time the KT monos were 50-60 watts ? He strongly recommended the 100 watt monos. I went a different direction and was going to get the current KT’s and run KT-120’s or 150’s but the Rogues became available. I tried the JBL’s with the Modwright KWI 200 we discussed and it drove them well. However the SQ was not enjoyable as the midrange glare and the Ti tweeters were way too bright. Prior to that I ran them with an inexpensive 30 wpc Antique Sound Labs 30 wpc integrated with Winged C EL 34’s and Tungsram 12AU7’s. The SQ was great but way underpowered. Anyway that’s my story and I’m sticking to it. That Modwright KWI was an early one and lacked a DAC that appeared later. I didn’t ask , but my buddy still might have it. He just kept buying gear and storing the used due to lack of interest. It’s been idle longer than this Rogue gear. The Hera was on a storage shelf in his home gym with other gear. His gym had 4 Dali bookshelves wall mounted with a built in passive sub and room correction. He has a theater in his living room and stereo in his outdoor shower. It’s always entertaining to visit him. And no I didn’t try the shower. 😆 Cheers, Mike |
There are several different versions of Quicksilver tube amplifiers referred to as "Monos", older models with speaker screw strips, and tube regulation, later binding posts added for speakers, and tube regulation pulled out. Those were about 60-80w max then. Later the next size transformer versions came out about 10 years ago, with newer and different switches [on front] started, in the 450v plate voltage range. You have to look at the transformers, power caps, power switch to ID them. Then came the largest transformers units, largest power caps in the 100w range. Then the most powerful "Monos" with higher plate voltage [650v] specifically designed for KT150 power tubes [this is what I have, no longer made]. I run either KT120s or K150s in mine but cannot run KT88s or smaller opt tubes, will burn them up faster with that higher plate voltage, on the edge for KT88s, and no EL34s or KT77s. The larger Mono 120s I have is only designed with extra voltage fire to run the larger opt tubes in their best operating window. More power, grunt, drive. My local dealer keeps one pair - uses them to run his largest electrostatic speakers and they do a nice job of it. These will become collectible amps imo, cannot get them new production any more - if that's what you need. Mike told me once they were expensive to make in this dedicated version. My version of the upgraded Mono 120s with KT120s or KT150s would power your JBLs, I’m running larger multi-driver woofer 4ohm speakers now.The Mono 120s barely get warm, nice. From there, before the pandemic start, Mike backed off on the specific big-gun Mono 120s or aka "KT150 monos" like I have, and he [consolidated 3-4 amps] went back to the side-chassis plug ins layout with the ability to run the smaller output tubes too, with lower plate voltage, the newer "KT Monos" you see today. Thought I’d share this since people just see the new amps on his site, others are archived now. Then new series is what I call the new consolidated design KT Monos. Those do not have the largest dual transformers btw, and its a more universal amp for those who like the lower power output tubes. Nice if you like KT77s, KT88s and you can still run the larger KT120s, KT150s yet lower plate voltage. I found you need the higher plate voltage and bias to run KT150s well. |
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