prego Posted October 5, 2007 Share Posted October 5, 2007 Heya all again, Lately I've bumped into records that on considerably average/high volume I get an annoying ssssshhhh suffix, especially on vocals. You know ... like a wierd ending to words, probably coming out from the horns, while the quality of the records is (known as) good. In the first minutes (while the amp is getting warmer) its noted easily, 10-15 minutes later it's less noted but still noted. My speaker are (moded) RF-7 and currently I run a Dynaco st 70 & conrad johnson pre. Speakers are toed in and are near walls. Transport is NAD and Squeezebox3. Interconnects between pre & power are cheap.. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted October 5, 2007 Share Posted October 5, 2007 itser .... Preamp Quote Link to comment Share on other sites More sharing options...
HarryO Posted October 5, 2007 Share Posted October 5, 2007 Sounds like a tube problem most likely in the pre. Although I had a 7199 in my Heathkit AA-111 that was noisy like that also a couple of weeks ago. Try switching L&R pre tubes and see if the noise follows. Harry Quote Link to comment Share on other sites More sharing options...
prego Posted October 6, 2007 Author Share Posted October 6, 2007 Haryy thanks, pre section of amp or preamplifier? Quote Link to comment Share on other sites More sharing options...
HarryO Posted October 6, 2007 Share Posted October 6, 2007 Anywhere but most likely preamp. If it's only the phono stage it will be quicker to find. Stay with the phono tubes until you find the noisy one. Harry Quote Link to comment Share on other sites More sharing options...
Deang Posted October 6, 2007 Share Posted October 6, 2007 "Lately I've bumped into records that on considerably average/high volume..." If it's not in every recording you play -- then it's specific to those recordings and you can't really blame anything in the system. If you're hearing it more than the comment above seems to indicate, a possibility is that it's being caused by reaching the limits of the ST-70 (clipping). Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted October 6, 2007 Share Posted October 6, 2007 How efficient are the RF-7s? Quote Link to comment Share on other sites More sharing options...
Strabo Posted October 6, 2007 Share Posted October 6, 2007 It could be caused by different things, pre, phono amp, tt, tt setup, cart, vinyl pressing, or vinyl condition. Is it in both channels? Does it happen on all recordings? Quote Link to comment Share on other sites More sharing options...
whamo Posted October 6, 2007 Share Posted October 6, 2007 He might not be using a TT. Does the sound you hear come from CD's or the Squeezebox? If it does you can try to bypass your preamp by using the gain control on your squeezebox. If you do that and the sound is gone then it's you pre. If not then it isn't. Make sure the volume control on your squeezebox is all the way down before you turn on your amp. Mark Quote Link to comment Share on other sites More sharing options...
Strabo Posted October 6, 2007 Share Posted October 6, 2007 I assumed "quality of the records" to mean vinyl. Guess he could have meant recordings instead of records. If digital, it can also come from the player. I hear it in my friends Pioneer Elite (47?) universal player at moderate levels. My point was, it can come from virtually anywhere and he has some troubleshooting ahead of him to figure out the source of the problem. It may be safe to assume that the speakers and amp are not an issue at this point, but who knows? Quote Link to comment Share on other sites More sharing options...
prego Posted October 6, 2007 Author Share Posted October 6, 2007 I've switched the L&R pre tubes, replaced the pre-amp interconnect - no change. Couldn't narrow the problem to either L or R channel, both made the same amount of sshh or "vocal suffix". The only audible improvment I got is when I moved on the amp from 4ohm to 8ohm. However, it introduced a very small hum - normal? Could it be that my pre amplifierneed tube replacment? (or the pre section on the amp 7199..) It repeats on other recordings as well, e.g. Nirvana - Polly, Katie Meula - Calling Off The Search. (EDIT: NO CLIPPING, I'm earing it on low volume as well) Quote Link to comment Share on other sites More sharing options...
frankphess Posted October 6, 2007 Share Posted October 6, 2007 I agree with Dean. The ST-70's clipping. RF-7's need more power than an ST-70 can provide to get to high volumes. Quote Link to comment Share on other sites More sharing options...
Deang Posted October 6, 2007 Share Posted October 6, 2007 He said, "...I run a Dynaco st 70 & conrad johnson pre...Transport is NAD and Squeezebox3..." He didn't mention a turntable. Erik, RF-7's are 102dB, but probably more like 99dB if on the four ohm taps of a tube amp. Heritage they ain't. Quote Link to comment Share on other sites More sharing options...
seti Posted October 6, 2007 Share Posted October 6, 2007 I was having a similar problem that showed up in three songs in particular. I took these songsw to a friends house and the ssss was still there. It was in the recording and I was relieved. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 6, 2007 Share Posted October 6, 2007 Perhaps he's noticing the effects of a high output impedance amplifier when connected to the widely varying impedance of the RF-7? Doesn't the RF-7 have an impedance spike around 1800Hz ish? A small bump in that region would increase the "shhhhhh"-ness of vocals. Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted October 6, 2007 Share Posted October 6, 2007 cut off your ears. Quote Link to comment Share on other sites More sharing options...
prego Posted October 6, 2007 Author Share Posted October 6, 2007 I've bypassed the preamplifier and connected the Squeezebox3 directly to the amp (the former has digital volume) and the problem persisted. I also tried all impedance (4/8/16) on the amp without any substantial relief to the problem. It happens on some recordings, right but I'm sure it shouldn't have been there. IMO, three options: 1. Peak in RF-7 horn 2. Peak generated by the crossover. 3. Amplifier is damaged. Quote Link to comment Share on other sites More sharing options...
prego Posted October 6, 2007 Author Share Posted October 6, 2007 In other words, I've got the sibilance disease. I'm not sure, but it's probably the amp. Anyone been to this journey with a dynaco st 70 that can shed a light ? Quote Link to comment Share on other sites More sharing options...
leok Posted October 7, 2007 Share Posted October 7, 2007 Do you have a power line filter (one that filters out RF)? Also, I'd stay with the 4 Ohm amp output. Leo Quote Link to comment Share on other sites More sharing options...
Deang Posted October 7, 2007 Share Posted October 7, 2007 1. Peak in RF-7 horn2. Peak generated by the crossover.3. Amplifier is damaged. I think we can rule out #1 since the mod addresses that. #2 is unlikely. When there are complaints about the RF-7, they are centered around the brightness and the shrill quality they take on at higher SPLs -- rarely does the complaint involve or specifically revolve around sibilance. I've never once heard any of the before-mentioned complaints after the modification is performed. #3 is a possibility I suppose, especially if the amp is in it original form and hasn't been looked over by a competent tech to ensure that it's operating properly. I did a search on that Squeezebox you're using -- please tell me you're not doing your playback with MP3's. Quote Link to comment Share on other sites More sharing options...
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