@wolf_garcia My wife thinks I'm being too sensitive about the hum, which doesn't show up at the speakers, as I've already described. Given the sellers description of the "quietest amp he's ever owned" I figured it should be literally dead silent, but now I'm hearing that there may be some small sound issuing from some of these amps, and perhaps the old circuitry of my dwelling is going to place the amp under different forces/conditions than what the seller experienced. As I've also described, it's definitely not impacting the sound, for the system is presenting, along with the speakers, the most beautiful music I've heard in this space. My main concern is longterm difficulty and having just picked up the amp I wanted to address it right away.
How deadly is transformer hummm...
Hello Folks,
I recently collected a lightly used (less than 50 hours) Dennis Had - Inspire - "Fire-Bottle." Within some few days, I noticed a humm emerging from somewhere within the chassis of the unit. As the unit was sold in "perfect" condition, I found the humm startling. Mind you, I've discovered absolutely no evidence confirming the sound is compromised; I mostly hear the sound within a couple feet of the amp, when the surrounding environment is silent.
This amp truly is a work of art. Nevertheless, I am now dealing with this 'humm' sound. I bought an Emotiva CMX-2 as a way to deal with DC offset, and this has not impacted the situation to any detectable improvement. Perhaps there is a slight improvement, but negligible. What to do?? Should I just relax, shake it off, and assume the amp will live well, or a down-the-road transformer replacement will simply become part of my experience with this amp? Should I put pressure on the seller to "right" the situation? He claimed, as I asked him, that it was the quietest amp he's ever owned. His add boasted that the fire-bottle exceeded amps from Pass Labs, a Cherry Amp, and one other that escapes memory. The seller has presented all of his communication in the manner of friendly professional etiquette.
Your thoughts are appreciated.
I recently collected a lightly used (less than 50 hours) Dennis Had - Inspire - "Fire-Bottle." Within some few days, I noticed a humm emerging from somewhere within the chassis of the unit. As the unit was sold in "perfect" condition, I found the humm startling. Mind you, I've discovered absolutely no evidence confirming the sound is compromised; I mostly hear the sound within a couple feet of the amp, when the surrounding environment is silent.
This amp truly is a work of art. Nevertheless, I am now dealing with this 'humm' sound. I bought an Emotiva CMX-2 as a way to deal with DC offset, and this has not impacted the situation to any detectable improvement. Perhaps there is a slight improvement, but negligible. What to do?? Should I just relax, shake it off, and assume the amp will live well, or a down-the-road transformer replacement will simply become part of my experience with this amp? Should I put pressure on the seller to "right" the situation? He claimed, as I asked him, that it was the quietest amp he's ever owned. His add boasted that the fire-bottle exceeded amps from Pass Labs, a Cherry Amp, and one other that escapes memory. The seller has presented all of his communication in the manner of friendly professional etiquette.
Your thoughts are appreciated.
Showing 14 responses by listening99
@bdgregory the hum is not audible from the speaker drivers. This is a mechanical event, coming from within the chassis. @brownsfan how do I detect tube issues like you describe- microphonics, etc? @stereo5 I always enjoy the humming of my wife, but it seems her tone is at a much higher frequency. I’m running the amp with a DAC and a CD transport... is it ok to unplug the RCA cables from the system, to rule out those components while this tube amp is on? I hear you don’t want to run a tube amp without connections... |
@mrdecibel So, if I open the amp and I'm tightening things, inserting bushings, etc., I will have the amp unplugged, and I'm wondering what I need to do to protect myself from errant charges that might stop my heart... My sense is you are pointing to the kinds of bushings that are customarily used along with screws/bolts to aid in keeping them tight...? example bushings: http://i.ebayimg.com/images/i/282179420188-0-1/s-l1000.jpg |
@jea48 the amp is entirely quiet at the speaker drivers; the amp was probably humming within the chassis from the start, but I did not hear it until a few days in. I bought the rubber washers, but further comments seem to indicate that tightening of the transformer screws is the first task. I will unplug the amp, remove the tubes, put on a pair of gloves and remove the bottom plate of the amp this evening, and then I will tighten things. I can look for clearance that might accept the new washers, but I don’t plan on adding those in yet... @wolf_garcia made an observation about the possibility that the washers will not do well with transformer heat. @atmasphere indicated they likely won’t fit, so the washers will be left out until I’m clear I won’t make things worse in the long run. Can I expect the components are pinned to the top of the chassis, Or affixed to the bottom plate, etc.? I will be careful and slow in removing things, but I’ll take any tips... |
I've got an email out to the seller of the amp, to see if he can reach out to Mr. Had, for some advice. The amp was made in April and there shouldn't be any transformer degradation of significance by this time. I would open it up with a little clear-firm guidance, but I am recollecting that my last rash of flirtation, soldering gun in hand, was over thirty years ago in a high school classroom. Thanks for the new vocabulary word: isomerics @wolf_garcia has me interested in the heat resilience of the purchased washers and I've discovered that they are more durable than the skin on my face. According to the Home Depot account for DANCO 1/2 flat washer 3/4" O.D.:
Can anyone speak to the expected problems with this kind of symptom? One person claimed it could clear up... I imagine the amp has around 100 hours on it by this time... |
Mr. Had has already responded, making an impression and stands firmly by his product. He's given me a test of sorts, to remove all of the tubes in the amp, to then see whether the amp hums. This I will address in the morning... more thereafter... Oh, I will include this marvelous detail about the amp's design: "The transformers are made with grain orientated steel and impregnated with a special anti vibration varnish. Also the chassis of all Inspire products is non-ferrous aluminum." |
@jea48 This two-story single family dwelling was constructed in 1986. I have not checked the mains voltage. I imagine this requires a volt meter, which I do not possess. I see a number of them for sale at the Home Depot, which is the closest such facility to my home. Is there a special type I should be using for this test? |
I want to update this thread, bring it full-circle, so to speak. I was able to finally develop a conversation with Dennis Had, who built the amp. He asked for a picture of the amp, which has been sitting on a thick slab small side-table type of stand, or pseudo-stand... He then asked me to put the amp on my kitchen counter and plug it in... he said the Inspired design is stable, doesn't need speakers, so I didn't have to haul any other equipment into the kitchen. The amp was noticeably more quiet in the kitchen. He then suggested I buy some sound coat, or similar product, claimed that the wood stand acted as a wood resonator, much like a piano. This is great news, because it's a wonderful piece of equipment and I've got some new open baffle speakers on order, which should complement the amp nicely. The speakers are based on the F-15 Lii Audio driver and boast 97db efficiency. This will be a single-driver setup - I'm thirsting for a vast soundstage! Thank you all, for participating in this discussion... |