AudioCircle
Industry Circles => LampizatOr => Topic started by: Dracule1 on 8 Aug 2015, 01:56 am
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I've noticed 60 Hz mechanical hum emanating from the GG DAC, presumably from the transformers inside this wonderful DAC. Have GG DAC owners experienced this? It's not loud enough to be intrusive but notieable. Also, when the volume is crank up, there is the same hum through the speakers. Again, not loud enough to be intrusive but noticeable during quiet passages of music. Any way to get rid of the hum?
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Hi Dracule,
To go through a couple of the obvious steps, did you try lifting the ground? Are your ICs shielded? Does your unit have volume control?
Where are you located? I'm happy to help trouble shoot.
Best,
Fred
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My 2 cents are:
AC mains over the nominal also may cause hum.
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There's probably a break in the ground of one of your IC cables or connectors. Do you have any DIY stuff?
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Hi, sorry for the delay.
The ICs are shielded. The hum isn't present through the speakers using other DACs using the same ICs. By lifting the ground, you mean using a cheater AC plug? The GG doesn't have volume control option. This issue only came about when the GG was introduce into the system.
My question: Is it normal for GG to have a little mechanical hum by itself? I'm not referring to the hum through the speakers.
BTW, the hum through the speakers gets louder as the volume is turned up.
Thanks.
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Hi, sorry for the delay.
The ICs are shielded. The hum isn't present through the speakers using other DACs using the same ICs. By lifting the ground, you mean using a cheater AC plug? The GG doesn't have volume control option. This issue only came about when the GG was introduce into the system.
My question: Is it normal for GG to have a little mechanical hum by itself? I'm not referring to the hum through the speakers.
BTW, the hum through the speakers gets louder as the volume is turned up.
Thanks.
The EI core transformers on it are likely to make a tiny bit of noise, but nothing you could hear unless you where either standing with it at maybe chest level, but more likely if you put your ear up to it.
Lifting the ground could be done with a cheater.
I bet it just has a bad connection to an RCA jack or such. You shouldn't hear anything in the speakers. That DAC isn't at the level where you'd expect to, it's one of the nicer DAC's one can get.
How are your skills with a multimeter? :D
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Could also be DC on the line to the transformer. Do you have any other tube gear?
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It really sounds like transformer mechanical hum, and it's louder than the EI power transformer in my 200 watt tube monoblock amps. I can hear it from the listening seat, but the listening room is very quiet and is dedicated for audio with extensive acoustic absorber and diffuser treatment.
What's worrying me is that you all are saying I shouldn't hear any hum through the speakers, but I obviously do. I'm not sure if Lampizator recommends lifting the ground. Does anyone know if this is a safe thing to do?
I do know how to use a multimeter, but I'm not willing to open up the GG as that will void the warranty.
I doubt is a bad RCA connection (unless it's from the RCAs on the GG) because the hum problem is not apparent with other DACs with exactly the same RCA connections.
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I've had problems in the past with transformer hum on many pieces of gear. It was so bad on some amps that I could hear the transformers hum from across the room. It turned out to be excessive DC on my AC lines. I have since put in new, dedicated circuits/outlets and now use a power conditioner that actively removes DC from my outlets. SO MUCH BETTER! No problems since. It's quiet with a black background.
I believe it's not the Lampizator but your electricity.
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There are AC filter/surge suppressor both in the audio room and in the main circuit breaker. Not sure if it filters out DC. It's hard to argue it is an AC line problem when this was never a problem in the past, at least not to this extent.
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Sadly, most AC power filters ignore DC completely. I would send it to get diagnosed, but I would also look at an AVA humdinger or another DC filter. Over time, I have had really expensive tube amps with humming transformers. Also, have you switched tubes in the DAC? A weak 5U4G once caused me a lot of grief before i thought to change the tube. Could be a bad tube as well. I had a bad phase inverter tube on an amp once and it caused a ton of hum.
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I have a lite 7 that I bought recently and it was making some very strange sounds out of both speakers. I assumed it wasn't a tube problem, but when I changed tubes the noise disappeared. The key with tubed gear and hums and noises is just to try every possible solution until it is resolved. Often the problem does lie in the tubes in my experience.
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Thanks all for the advice.
That's a good idea. Perhaps the tubes are the problem. Since the hum is coming from both channels, a different rectifier tube may due the trick. May be contacting Lampizator is a good idea too.
Sending the GG for diagnosis would be a PITA at this point. A DC filter is another option to try.
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You could easily have two issues going here...
The internal hum (most likely) from the transformer, could be due to DC on the lines OR it needs tightened up a bit. I even read of some putting thin cork sheeting under a problem humming/vibrating transformer in other gear, elevating the issue.
Your hum from the speakers, that raises with the volume level is going to be something else... Hmmm...
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I'm sure the internal hum is from one of the power transformers. Unfortunately, the GG is "sealed" so that if the seal is broken by opening up the chassis, warranty is void. So one can not open the unit to see if anything is loose.
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The HumDinger may fix your hum issue. If it doesn't, well, it does have a satisfaction guarantee.
Frank Van Alstine
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I'm sure the internal hum is from one of the power transformers. Unfortunately, the GG is "sealed" so that if the seal is broken by opening up the chassis, warranty is void. So one can not open the unit to see if anything is loose.
Im the Co-North American distributor for Lampizator. I PM'ed you Dracule. If you communicate with me, perhaps I can help you :scratch:
Thx
Rob
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Hi Rob, I got in contact with Lukasz. Let me see what he says. Can you PM me your phone number in case? Thanks for your interest in helping.
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Curious Dracule1 What kind of amps are you running with the GG?
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I'm planning to try the Sophia Electric Princess 274B rigid plate rectifier tube to see if the hum through the speakers go away. It can handle up to 160 mA. Can someone confirm this tube is OK for the GG? I don't see a reason why it shouldn't be compatible, but you never know. Currently my GG uses the stock EL 5U4G.
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Rob, please check your PM.
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Yes the 274B is compatible.
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Update. The hum through the speakers has pretty much been solved. When the EML 45 tubes were shielded with the supplied tube cages and grounded properly, the hum was attenuated by ~10 dB at normal listening volume. Seems the EML 45s are very sensitive to hum. Now, I have to have my ear about 1 feet from the speakers to hear a slight hum at normal listening volume. It no longer is noticeable during quiet music passages. With the tube cages in place, I think there is subtle loss of warmth in the sound, which I kind of miss. Anyone using the tube cages with their GG?
The slight mechanical transformer hum still exists. It is audible from the listening position when no music is playing. Once the air conditioner kicks in, the mechanical hum gets drowned out. I think this is normal, but I ask if other GG owners are experiencing the same mechanical hum?
Rob recommended the TJ Fullmusic 300B SE to try with the GG. I did a search and only found sellers in China (mostly eBay) selling these which are quite pricey at $750/pair. Can anyone recommend a reliable sellar? Anyone try the Elrog 300B?
Thanks!
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Elrogs seem unreliable.
What about the Sophia eletric Carbon Princess and the Royal princess? they are much cheaper.
Did you also try Cunningham vintage 345 globes and RCA 245 globes? They have oodles of MR warmth and are fairly cheap.
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Hi Wisnon, thanks for your kind input.
I've bought Sophia Electric 6sn7s and 274B rectifier tubes before. I stopped buying from them when l I realized their tubes look like rebadged TJ Fullmusic tubes. SE claims they are special selection tubes made just for them, but I have seen no spec sheet showing them to be any different than the standard TJ tubes. Construction wise they look exactly the same, and the TJ Fullmusic 300b are hundreds of dollars cheaper. The Royal Princess is going for $1200/pair, and I think the equivalent TJ tube is the 300B SE which sells for $750 on eBay.
I haven't tried the vintage tubes you mention, which can sound too warm for my taste.
I haven't seen anything online stating Elrogs are unreliable. Is this from personal experience?
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Drac, Elrogs are not personal experience, but feedback from people I know…nuff said. The Japanese Takasuki (sp?) are supposed to be great.
Try these:
http://www.ebay.com/itm/2X-VAIC-VV-300B-TRIODE-TUBES-USED-LOW-HOURS-FOR-SINGLE-ENDED-END-DIY-AMPLIFIER-/252046361348?hash=item3aaf224304
or
http://www.ebay.com/itm/KR-AUDIO-KR-300B-Tubes-MATCHED-PAIR-Super-Quality-Tubes-on-Market-/391231539879?hash=item5b17378aa7
or
maybe as alternative
http://www.ebay.com/itm/KR242-KR-LOGO-MATCHED-PAIR-WHOLESALE-PRICE-VALVE-TUBE-/171425423022?hash=item27e9c05eae
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the 345 and 245 are cheap and still worth a shot. Also CX301
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Do NOT get the big KR Audio tubes.
They are not reliable.
We had to return a few 845 tubes to The US Distributor so we know for a fact.
On the other hand, their 2A3s are very very good.
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The 845 does NOT work in the Lampi Dac, so not an issue.
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My bad.
You are correct.
Their 300B & 2A3 tubes are just fine.
Thanks,
The 845 does NOT work in the Lampi Dac, so not an issue.
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Norman,
Have you cleared the UU4 with Lampi? It's a 4 volt rectifier, not a 5 volt. 25% over spec seems to be pushing it pretty hard.
Shawn
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My bad.
You are correct.
Their 300B & 2A3 tubes are just fine.
Thanks,
Not a prob. Thanks for the info anyway…always useful.
Shawn, is the UU4 the 596? I thought the 596 was a 5v recti. On first blush, I would ONLY use a 5v recti.
Edit: Shawn my bad, i read it too fast. UU4 os 4v and I guess unsuitable. i will edit my post above...
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Final update.
The mechanical transformer hum issue I've been having with the GG has been solved. As sfox7076 pointed out, there was DC on my AC line and the AVA humdinger completely removed the hum. Interestingly, my tube amp has no mechanical hum issue at all without the humdinger. According to my amp designer, he designs his power transformers so DC on the AC has minimal if any effect. Thanks sfox7075! :thumb:
As for the hum I get through the speakers, the tube shield has helped out a lot. The EML 45 is the most susceptible to hum. The Psvane 101D has the least hum. The TJ Full Music 300B SE is somewhere between the two. My next stop is the Takatsuki 300Bs.
Thanks all for you help.
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I hear that the Px4 are the quietest tubes of all.
Let us know what you think of the Takats!
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Glad to help. It is likely that the amp designer built something similar to the humdinger into his amp power supply. My tube amps have something similar in them. And, well, I have also learned some transformers are more susceptible than others. Regardless, it is the first thing I think of when I hear there is transformer hum. Some people argue that things like the humdinger could degrade sound, but I just cannot believe that.
Shawn
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One other thing, don't bother looking for the DC source unless you really want to lose your mind...
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I hear that the Px4 are the quietest tubes of all.
Let us know what you think of the Takats!
So far I like the Psvane 101D and TJ 300B about equally, but for different reasons. The Psvane is more dynamic with better low end extension. The TJ has a more relaxed sound and almost as dynamic and extended in the low bass. The EML 45 is not as transparent, extended, and dynamic as the other two and is warmer sounding. However, I'm using the Psvane 274B with the 101D and 300B. I was using the EML 5U4G withe 45. So not apples to apples comparison. Need to try the 45 with the Psvane 274B to make final conclusion.
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Glad to help. It is likely that the amp designer built something similar to the humdinger into his amp power supply. My tube amps have something similar in them. And, well, I have also learned some transformers are more susceptible than others. Regardless, it is the first thing I think of when I hear there is transformer hum. Some people argue that things like the humdinger could degrade sound, but I just cannot believe that.
Shawn
My amp designer said he doesn't use anything like the humdinger in his amp design. According to him, it's all how the power transformer itself is designed to be less susceptible if not immune to mechanical hum. He designs his own power and output transformers.
When I first used the humdinger, I used a familiar power cord from the AC outlet to the humdinger. I didn't like what the PC was doing to the sound. It actually made the sound more thin and anemic. So I bought an adapter that plugs the humdinger directly into the AC outlet. Now, I get the sound I was used to without the mechanical hum. I don't think the humdinger itself degrade the the sound, more likely the PC they're using to connect the humdinger to the AC outlet.
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OK.
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So far I like the Psvane 101D and TJ 300B about equally, but for different reasons. The Psvane is more dynamic with better low end extension. The TJ has a more relaxed sound and almost as dynamic and extended in the low bass. The EML 45 is not as transparent, extended, and dynamic as the other two and is warmer sounding. However, I'm using the Psvane 274B with the 101D and 300B. I was using the EML 5U4G withe 45. So not apples to apples comparison. Need to try the 45 with the Psvane 274B to make final conclusion.
EML 45 mesh is better and more expensive than the solid plate version.
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EML 45 mesh is better and more expensive than the solid plate version.
I have the EML 45 mesh plate. I want to try it with the Psvane 275B rectifier. May be this combination will sound better than with the EML rectifier.
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I have never heard the EML recti…
All my rectis are vintage. LoL