ThomBoh Posted March 4 Author Share Posted March 4 15 hours ago, Silverfoxvtx1800 said: I can personally tell you that the solid state Class A,Pass Labs XA25 and the Pass Preamp or the int-25 integrated Pass don’t hum and are dead silent in the Klipsch speakers…last time I looked there was a couple Pass Labs int-25 amps on USA audiomart…at a decent price….and no tube worries… I don't doubt it! Pass makes great stuff, and of course solid state is immune to the type of hum we're discussing here. I might try them out one day, but right now I'm enjoying tubes (my UFO25s sound fantastic and humless configured as differential monoblocks). 14 hours ago, 83 LSIs said: Anyone that worries about tubes probably shouldn't have a tube amplifier, hum or no hum. 😉 I find it odd that the UFO25 and 300B amplifiers need to hum to sound good? Having owned or heard several not 25 versions of the SE84, an original Taboo, the SE34i, and even owned the original blue Torii (a different sort of p/p) without hum issues, not to mention other brands of single ended tube amplifiers that were quiet. Even my diy ~7 watt SET amplifier is silent. My understanding from my discussion with Steve is that the hum is certainly not required to sound good, but is required for the amp to sound exactly the way he wants on the types of speakers he is targeting. He said it would still sound good without the internal hum, just not special in the way that he wants. Yeah my SE34I.5 is nice and quiet on my La Scalas, very very little hum, and fine for everyday use. Doesn't sound as good as the UFO25 (in mono) though! Based on the testimonies I've gathered and reviews read, the non-25th anniversary UFOs seem to just have less internal hum than the 25th anniversary version. Not sure why. Steve has told me that different models of his amps indeed do have different levels on internal hum (e.g. 300B > UFO25 > SE34I in hum level). Quote Link to comment Share on other sites More sharing options...
jjptkd Posted March 4 Share Posted March 4 On 2/20/2024 at 7:52 PM, ThomBoh said: This hum will be louder at 105 dB, sure, but mine is pretty bad. What I'm trying to determine is whether or not this is completely the inherent hum of the amp (which means that Decware amps and La Scala AL5s and Khorns are just not a good match), or if there's something else going on in my case which is making it worse than it should be So is the hum coming through the speakers or from the amp itself? Forgive me if this has been asked already. 60db hum is obviously unacceptable. 1 Quote Link to comment Share on other sites More sharing options...
ThomBoh Posted March 4 Author Share Posted March 4 1 hour ago, jjptkd said: So is the hum coming through the speakers or from the amp itself? Forgive me if this has been asked already. 60db hum is obviously unacceptable. From the speakers. There is a very faint buzz from the amp's transformer itself, but that is very quiet and absolutely negligible here. Quote Link to comment Share on other sites More sharing options...
Khornukopia Posted March 5 Share Posted March 5 In all fairness to the reputation of the amp builder, I think it would be considerate to prove that your house wiring, and/or your electric power source is not contributing to the hum. I have witnessed some strange things with electrical circuits over the years and am really curious about the cause of your hum. In the 2 weeks since posting to the public on this forum, have you carried your amp to a friend's house during this time to compare? Sometimes the process of elimination is the only way to realize what is or is not causing a problem. Quote Link to comment Share on other sites More sharing options...
ThomBoh Posted March 5 Author Share Posted March 5 (edited) 25 minutes ago, Khornukopia said: In all fairness to the reputation of the amp builder, I think it would be considerate to prove that your house wiring, and/or your electric power source is not contributing to the hum. I have witnessed some strange things with electrical circuits over the years and am really curious about the cause of your hum. In the 2 weeks since posting to the public on this forum, have you carried your amp to a friend's house during this time to compare? Sometimes the process of elimination is the only way to realize what is or is not causing a problem. I agree. I've had two electricians over, and consulted with a third, all of them have said that everything looks great. The wiring is much newer than the rest of the house and is modern. Ground examined and tested, as were all outlets. I also got my own outlet tester for my own gratification. I don't have any friends with passive speakers, unfortunately. I do plan to bring it to a hifi store that has La Scalas or KHorns set up at some point, but have not been able to yet. It seems unlikely at this point, though, that there is any issue with my house's wiring, and Steve has agreed that this is the case. Nonetheless, I will test the amp elsewhere whenever I get the chance, as I think I'll need this to satisfy my own curiosity. But bear in mind this test needs to be on highly efficient speakers to be meaningful here -- having a small amount of hum from normal-high efficiency speakers is within spec according to Decware. Edited March 5 by ThomBoh Quote Link to comment Share on other sites More sharing options...
Khornukopia Posted March 5 Share Posted March 5 36 minutes ago, ThomBoh said: I agree. I've had two electricians over, and consulted with a third, all of them have said that everything looks great.,, ... Nonetheless, I will test the amp elsewhere whenever I get the chance, as I think I'll need this to satisfy my own curiosity. Please do inform us, no matter how much time passes. It will be educational for all of us. 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted March 5 Share Posted March 5 120 Hz @ -68dB pretty much sums it up at least for me...not even in the realm of acceptibility. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted March 6 Share Posted March 6 Can we hear -68db? Seriously, I am waiting on two of these amps. Quote Link to comment Share on other sites More sharing options...
ThomBoh Posted March 6 Author Share Posted March 6 3 minutes ago, mark1101 said: Can we hear -68db? Seriously, I am waiting on two of these amps. That spec doesn't tell you what you will hear from your speakers in your room at listening position. For me and my speakers, this translated to a 58ish dB hum at listening position, which is very, very noticeable (for reference, with the amp off, ambient noise in the room is about 43 dB). Happy to send you a video if you would like. Which amps did you order? I'm talking specifically about the SEWE300B, but the UFO25 gave 55-56 dB of hum which is also not bearable imo. Which speakers were you planning to pair them with? Quote Link to comment Share on other sites More sharing options...
mark1101 Posted March 6 Share Posted March 6 I bought a pair of SE84UFO. I bought these on 4-10-22. At that time I was around number 1200 on the real time build sheet. Today I am at around number 380. Doing the math Decware builds around 400 to 450 amps per year (all types included). It will be close to another year for me. So around a 3 year wait. Right now I see over 2400 on the list. That would be over a 5 year wait (closer to 6) the way things are presently going. Enjoy fellas. I feel like if I eventually don't want these amps I could double my money in about an hour. By the way I can use them on any of the Heritage in my signature. I had planned on the lascalas. I require near silent equipment. Anything else and it won't be in my house. Quote Link to comment Share on other sites More sharing options...
ThomBoh Posted March 6 Author Share Posted March 6 51 minutes ago, mark1101 said: I bought a pair of SE84UFO. I bought these on 4-10-22. At that time I was around number 1200 on the real time build sheet. Today I am at around number 380. Doing the math Decware builds around 400 to 450 amps per year (all types included). It will be close to another year for me. So around a 3 year wait. Right now I see over 2400 on the list. That would be over a 5 year wait (closer to 6) the way things are presently going. Enjoy fellas. I feel like if I eventually don't want these amps I could double my money in about an hour. By the way I can use them on any of the Heritage in my signature. I had planned on the lascalas. I require near silent equipment. Anything else and it won't be in my house. Well, the sorta-good news here is that the SE84UFO is a different design than the UFO25, and might have a different noise spec. As evidence in this direction, Andrew Robinson specifically mentioned in his La Scala review that the UFO2 was a fantastic match for the La Scalas, so that tells me that the UFO2 must have a lot less hum than the UFO25, and I'd expect the UFO to be similar to the UFO2 rather than the UFO25. But this is all "informed speculation" on my part. If I come across a UFO or UFO2 on the used market I might grab it just to compare against the UFO25 and try and satisfy my curiosity on this. Better news is that if you bought a pair of the UFOs with the intention of using them as differential balanced monoblocks, then you're in the clear. My UFO25s in balanced mono are humless and sound great on my La Scalas. Quote Link to comment Share on other sites More sharing options...
KT88 Posted March 6 Share Posted March 6 From what I see on Decware's website, the main difference is that the SE84UFO25 uses three separate rectifier tubes, one for each tube in the signal path. The "simple" UFO and UFO2.1 do not have this complexity and they use only one rectifier tube. I wonder if that has anything to do with the hum? Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted March 6 Share Posted March 6 Only one rectifier, the other tubes are voltage regulators. There are quiet amplifiers that use VR tubes. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.