@mulveling That 20 Hz rating is at one meter. They do better than most speakers, but the issue is that you have to boost 20 Hz 10 dBSP to get the right balance. This will push the S7's woofers into their nonlinear zone at rock and roll volume increasing distortion. This will also torture the amp. Breaking out 100 Hz down to a dedicated subwoofer system decreases distortion in the main speakers and allows you to get the proper boost without torturing the main system.
It was the output tubes all along...
I think I finally reached the balanced sound I have been seeking for years. I've had my VAC 200 IQ's monos for about 7 years. When auditioning the amps I was comparing these to a similar priced Pass solid state amp. I liked the bass of the Pass, but really liked the tube sound of the VACs. The VAC's come stock with KT 88's which seemed a little tame to me at the time. Mike at Suncoast Audio was incredibly generous with his time during this process and rolled some KT-120's and then finally the new KT-150's over the course of a couple of hours. The KT-150s added the bass slam that was equal to the Pass but had the nice warmth of the tubes to boot. Sold! Kevin Hayes was great-switching out the KT-88's for the KT-150s when my units were manufactured. This was my first big boy purchase-a move up from an older MacIntosh unit. We moved a few times and 5years ago I was able to build a listening room with optimal dimensions in what will be our last house. By this time Mike had been able to secure lightly used Magico S7 speakers for me and things sounded pretty good. I've sequentially added rugs to the wood floor, first reflection point GIK art work, and other acoustic treatmens. The bass was a little prominent, so I added bass traps as well as The Swarm subwoofers. Things sounded great. Then I added the secret sauce-VAC Master preamp with phono. I was stunned at the sound I was hearing. I added Valhalla 2 interconnects and speaker cabling with further improvements. However, I started to notice the bass had become somewhat intrusive on about 30% of my records (mostly classic rock, jazz, blues). I paid extra attention at live events to see what proportion the bass occupied in a variety of musical events. About this time I found several excellent discussions on tube rolling here on Audiogon. I paid extra attention to the posts of @Mulveling as he has owned most of my current equipment and has lots of experience with different tube combinations. I played with some NOS input tubes which further improved the sound stage and overall timbre, but the pesky bass persisted. It got in my head big time. I stopped listening to the music, rather focusing on where and when the bass would vie for sonic dominance. I reread some of the tube articles where @Mulveling stated he didn't care for the sound of KT-150s and found the best sound was achieved with KT-120s. I talked to Kevin Hayes who prefers the KT-88s. What to do? At this time I was sure I needed a tube change, but not sure where to go. I spoke with Mike from Suncoast, who actually had come previously just for a listen. He liked the bass, but suggested I try the KT-170's. He said it was the best sounding and tight bass he had heard and a has a set up featuring them in his shop. I polled this group, but there was no one with an opinion on the virtues of the KT-170 over the KT-150 tubes. Sooo. I am now 400 hours in with the KT-170's. The bass is spectacular! Fast and full and but balanced. Didn't lose the slam. No more subterranean rumbles, either. The sound stage is broad with good depth and instrument placement. The mids and highs are great. I had one audiophile friend over for a 3 hour listen. He had heard the system before the tube switch and had commented after prompting that he didn't like the bass sound at all and it wasn't 5 minutes in that he exclaimed that the sound "was perfect". I am now hearing only music. Using the retrospectuscope, as my system incrementally became more revealing, the faults of the KT-150 slowly emerged. I see no detriment to any aspect of my sound after making the switch to the 170s, only a much much better bass. Hopefully this post can help inform others as to what to expect with the KT-170 tube, especially if they are running KT-150s. I did check with Kevin at VAC who indicated there was no conflict with this tube, as the parameters were similar to the KT-150, but this may not hold true for other systems-so please check if you decide to try the KT-170's. However, it's still not clear what tube is actually the best for this system...
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- 26 posts total
@mijostyn I don't really have digital phobia at all. I started with a room and a pair of monoblocks in my new house. I was ALL digital until about 9 years ago. Actually most of my vinyl is from my youth, but I swallowed the CD blue pill and didn't listen to vinyl for 3 decades, building my cd/sacd collection. My Meridien cd player opened my eyes to digital, but listening to vinyl again opened my ears. I have a good friend who has MBL Radiahlstrahlers (the big boys) with top of the line Esoteric digital front end. Sounds great-but certain vinyl sounds better in my room compared to his digital source. I know GIGO. Needless to say, I'm not digital phobic, I've just been wandering down the analog trail. At some time, I will modernize the digital side of my Rome. Just not yet. I do appreciate the path that you have illuminated. Also, I only listen to rock and roll volume at rock venues. I rarely listen above 90 dB and wear hearing protection while working as my work environment can be noisy. @Mulveling. I have listened to my system with the Swarm off. Not quite as good as with it on. My system doesn't suffer from loss of low end. I'd like to think I'm helping tune the room with the distributed bass array. My room isn't huge (25x14x10) at all. I think Mijostyn may have hit the nail on the head with the concept of a stronger bass array. I spoke with Mike at Suncoast Audio who really knows my system and fully agrees-new sub array with bass DSP makes some sense to me. @wsrrsw You are absolutely correct in noting that the KT 170s are wider than the KT-150s. Fortunately for me, the VAC configuration allows for plenty of space. I should have mentioned that in my original post-thanks for doing so. |
@orthomead My amp had to be modified to use the KT170 tubes. That i should be dotted. If you get ‘em (Do!) please report after they have settled in. |
@wsrrsw I have over 400 hrs in. I'll refer you back to my original post which details the adventure and results. I love em. |
@orthomead 90 dB is pretty loud! The loudest I listen is 95 dB. The reason to use the bass management I previously discussed is to create the FEELING of a live performance a less than ear shattering volumes. It is, in large part, the visceral component of frequencies below 100 Hz that make live music so exciting. I was over a friends house two days ago. He has a wonderful system. Serblin K'tema speakers, CS Port turntable, MSL Signature Platinum cartridge, Bricasti amp, DAC and transport. We were listening to, of all things Vini Vici (disco dance music with heavy synth bass). He pulled his meter out and it read 104 dB! I had no idea it was going that loud. I played the same cut at home and 95 dB blurred my vision. My friend, having had a bad experience in the past, will not use subwoofers and the fundamentals of the synthesizer bass were AWOL. He is beginning to warm up to the idea again. Staying on topic, with a proper subwoofer system you can drop back to the KT88's better sonics and still have a much more powerful system than you would with KT170s and what you are presently doing. |
- 26 posts total