USNRET Posted March 4, 2017 Author Share Posted March 4, 2017 4 minutes ago, Schu said: Is there an impedance mismatch? I dont see the specifications on the 275. I'd like to know what tubes are being used... These are stock McIntosh factory tubes (KT-88s out) copied from a guggle search Also like the original, the new MC275 uses four KT88 power-output tubes, three 12AX7A input and phase-inverter tubes, and four 12AT7 voltage-amplifier and driver tubes.Read more at http://www.stereophile.com/tubepoweramps/mcintosh_mc275_power_amplifier/index.html#OxyZtiYeAyGgtRol.99 Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted March 4, 2017 Share Posted March 4, 2017 Take the 2500 out and run direct from the OppoTo troubleshoot Quote Link to comment Share on other sites More sharing options...
USNRET Posted March 4, 2017 Author Share Posted March 4, 2017 I just changed the topic to HORRIBLE to WONDERFUL Apologies for my late return I have been too laid back grooving on tunes. All back to normal polarity, still using un-balanced (try balanced later) I went from 8 ohm tap to 4 ohm tap. See you later, I have a fresh drink and some blues on XRCD cued up. 1 Quote Link to comment Share on other sites More sharing options...
garyrc Posted March 4, 2017 Share Posted March 4, 2017 Now all we need is for someone to explain why the taps make so much difference. Any takers? What tap is recommended to run Khorns with a tube amp? Is this due to an ideosyncrasy of the McIntosh? Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted March 4, 2017 Share Posted March 4, 2017 My Mc30s, Mc240, and Mc225 are all on 8 ohm taps Quote Link to comment Share on other sites More sharing options...
ricktate Posted March 4, 2017 Share Posted March 4, 2017 I have a hard time believing the TAP was the cause. But if it worked and your happy ...cool. I would investigate further if it was me..... Those look like brand new units??? K-horns should work on 8 OHM tap. 1 Quote Link to comment Share on other sites More sharing options...
USNRET Posted March 4, 2017 Author Share Posted March 4, 2017 I will be going thru the setup again later today. Yes, this turn of events surprised me as well. The pre is new (I have maybe 5 hours on it thru the Emo) and the amp is a used one. Quote Link to comment Share on other sites More sharing options...
TubeHiFiNut Posted March 4, 2017 Share Posted March 4, 2017 The impedance of a speaker is usually termed "nominal". I make it a practice to try the 4, 8 and 16 ohm taps to see which one sounds the best (to my ears). Differences? Yes, but not "night and day". As others have stated, I would still be looking for the root cause of the issue. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted March 4, 2017 Share Posted March 4, 2017 bass bins are wired properly to the crossover networks? Quote Link to comment Share on other sites More sharing options...
Schu Posted March 4, 2017 Share Posted March 4, 2017 ... Quote Link to comment Share on other sites More sharing options...
russ69 Posted March 4, 2017 Share Posted March 4, 2017 Stereophile suggested that the 4 ohm taps sounded better. Your pre-amp is still very fresh, perhaps some more hours will improve things even more. 1 Quote Link to comment Share on other sites More sharing options...
Max2 Posted March 4, 2017 Share Posted March 4, 2017 9 hours ago, jimjimbo said: My Mc30s, Mc240, and Mc225 are all on 8 ohm taps If you could only have one of those, which would it be? Thanks Jimjimbo Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted March 4, 2017 Share Posted March 4, 2017 1 hour ago, Max2 said: If you could only have one of those, which would it be? Thanks Jimjimbo Right now, from everything I've heard in the last 2 weeks, the MC225. It's very, very close, but they all have different "signatures". The 225 brings a bottom end that surprised me. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted March 4, 2017 Share Posted March 4, 2017 3 hours ago, TubeHiFiNut said: The impedance of a speaker is usually termed "nominal". I make it a practice to try the 4, 8 and 16 ohm taps to see which one sounds the best (to my ears). Differences? Yes, but not "night and day". As others have stated, I would still be looking for the root cause of the issue. Absolutely agree with this, should be looking for an issue with the 8 ohm taps. I would immediately contact Audio Classics and let them know. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted March 4, 2017 Share Posted March 4, 2017 So given this thread, can one of you geniuses enlighten us on what the sonic/tonal differences "should be" switching between 4/8/16 ohm taps, with everything being equal, say a tube amp/khorns/la scalas/etc...??? I'll be honest, I've never hooked anything to my amps other than on to the 8 ohm taps....What am I missing? (If anything?) Quote Link to comment Share on other sites More sharing options...
Max2 Posted March 4, 2017 Share Posted March 4, 2017 2 hours ago, jimjimbo said: Right now, from everything I've heard in the last 2 weeks, the MC225. It's very, very close, but they all have different "signatures". The 225 brings a bottom end that surprised me. Thats cool you can sample all three. Have heard the 30's on La Scalas and man did they sound good. I have read the shootout comparisons and it seems its like you said, all good, but each different in their own. It seems someone picks one model or the other as a standout and it makes you wonder how much room for error there is setting up each model close to an optimum level. Quote Link to comment Share on other sites More sharing options...
Max2 Posted March 4, 2017 Share Posted March 4, 2017 46 minutes ago, jimjimbo said: So given this thread, can one of you geniuses enlighten us on what the sonic/tonal differences "should be" switching between 4/8/16 ohm taps, with everything being equal, say a tube amp/khorns/la scalas/etc...??? I'll be honest, I've never hooked anything to my amps other than on to the 8 ohm taps....What am I missing? (If anything?) I may be wrong, but wouldn't higher ohms equal less THD ? Quote Link to comment Share on other sites More sharing options...
USNRET Posted March 5, 2017 Author Share Posted March 5, 2017 Well everything suks today no matter the tap. I have gone down to over the air TV audio out to Emo Mini-X amp to speakers and my best description is that any volume over about 60-65 dB causes all vocals / voices to have a very pronounced lisp. Squawkers are easy to disconnect (10ish ohms). I'll have to remove the backs and checks the tweeters. Thoughts? Quote Link to comment Share on other sites More sharing options...
USNRET Posted March 5, 2017 Author Share Posted March 5, 2017 Complete tear down and build up with all new terminations. Tweeters 5.8 ohms, mids at 10.2. I haven't turned the Mc on yet just hearing crappy / broken mids from the Marantz / Emo / TV. Gotta be speaker related. I guess my next step is to roll my single Belle into a channel for a listen. Quote Link to comment Share on other sites More sharing options...
davis419b Posted March 5, 2017 Share Posted March 5, 2017 Why do you have to remove the backs to check the tweeters ? Quote Link to comment Share on other sites More sharing options...
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