Heathkit W5M too quiet

[FireGuruMN]

Oh, and the popping seems to only happen now when the amp is shut down for a short period of time and turned back on. I'm guessing it is a multi-section capacitor discharging when the rectifier comes on line. Don't those 5R4GY's have some sort of "soft start" built into them? At least that is the area where the noise is coming from. I'm surprised that there is enough charge in the caps to make a pop though. Time to find another WA-P2 preamp.

 

[billyz]

Oh, and the popping seems to only happen now when the amp is shut down for a short period of time and turned back on. I'm guessing it is a multi-section capacitor discharging when the rectifier comes on line. Don't those 5R4GY's have some sort of "soft start" built into them? At least that is the area where the noise is coming from. I'm surprised that there is enough charge in the caps to make a pop though. Time to find another WA-P2 preamp.

5r4 's are not considered a controlled warm up rectifier. The 5ar4 is . its fun to watch the voltages ramp up with a GZ34 ( 5ar4 ).

 

[century tek]

I can't say that it sounds like a good idea sticking my ear next to something that sounds like it is making a high voltage arc. . The sacrifices we make for science. . .

Lol, if it hasn't exploded, you'll be fine! Besides, it's not like you are NOT using any common sense to find the problem right??

 

[eiraved]

But I would still like to increase the sensitivity so I don't need to introduce another component into the system. I'm considering using the preamps that came with these W5M's but something tells me that is going to be a big hit in signal quality. And I only have one preamp at this time.

You can raise the amp sensitivity through modifications, but IMO the volume won't satisfy you to the point where you'll ditch adding a preamp. I own three W5M amps with mods incorporated and I can turn the iPod volume up full without it bothering the wife's sensitive ears. Attach a preamp to the mix and I can't get the volume much past halfway before she's yelling at me! BTW, the iPod sound quality sucks when used as a preamp through the 3.5 mm jack. Your sound quality will be much improved using the iPod's 30 pin connector through a preamp's aux RCA connection.

 

[FireGuruMN]

Good to know that others are using preamps with the W5M's. I will have to keep one in the setup. My main audio source is a Schiit Modi2 Uber DAC playing FLAC files off a NAS array. My workshop has a Muse DAC with the capacitors replace with proper audio caps. It has a headphone output that has a little stronger signal than the RCA outputs. But neither was enough to power the W5M. I'm going to talk some proper voltage readings with a scope next time I have the W5M's on the bench to replace the loose socket. More to follow.

 

[whoaru99]

Oh, and the popping seems to only happen now when the amp is shut down for a short period of time and turned back on. I'm guessing it is a multi-section capacitor discharging when the rectifier comes on line. Don't those 5R4GY's have some sort of "soft start" built into them? At least that is the area where the noise is coming from. I'm surprised that there is enough charge in the caps to make a pop though. Time to find another WA-P2 preamp.

What are you talking in terms of on/off/on time? Tube amps, generally, don't like short on/off/on cycles.

 

[FireGuruMN]

I am usually waiting several minutes between cycles. Not enough to worry about short cycling. I blew the main fuse on my AU-X1 through short cycling. It takes a while for all those monster caps to discharge.

I was curious about how hot I should let these amplifiers get before giving them a break. Seems like I can play them for an hour and the power transformer and output transformer are warm to the touch. I have to figure they are a lot hotter inside all that tar. Someone had a thread that mentioned waking up from a nap to find his output transformers melted. I cannot find that reference now. I am hoping to avoid that.

I'll be drawing more power once I hook up the preamps so that will be a greater concern.

I did found this interesting thread:
http://audiokarma.org/forums/index.php?threads/heathkit-w5m-restorations-and-mods-ideas.753201/
It describes some interesting mods. They are mostly for protection it would seem. I wonder if the popping sound I am hearing could be screen arcing like they discuss.

 

[gadget73]

Should be able to run them indefinitely without problems. If they won't handle that, something isn't right.

 

[primosounds]

I am usually waiting several minutes between cycles. Not enough to worry about short cycling. I blew the main fuse on my AU-X1 through short cycling. It takes a while for all those monster caps to discharge.

I was curious about how hot I should let these amplifiers get before giving them a break. Seems like I can play them for an hour and the power transformer and output transformer are warm to the touch. I have to figure they are a lot hotter inside all that tar. Someone had a thread that mentioned waking up from a nap to find his output transformers melted. I cannot find that reference now. I am hoping to avoid that.

I'll be drawing more power once I hook up the preamps so that will be a greater concern.

I did found this interesting thread:
http://audiokarma.org/forums/index.php?threads/heathkit-w5m-restorations-and-mods-ideas.753201/
It describes some interesting mods. They are mostly for protection it would seem. I wonder if the popping sound I am hearing could be screen arcing like they discuss.

Tube equipment was designed to be played all day without problems. The problem is usually with unrebuilt units where because the coupling caps start to leak DC the bias on the power tube is no longer at its proper level and the tube starts to runaway that is red plate. This will draw excessive current thru your output trans and cause it to fail. It seems that the original output trans are not very tolerant of current overload. Anyway, i would not worry about the heat issue unless you start to smell something overheated. I always run my amps without the chassis cover if at all possible. This allows better heat dissipation.
About the popping sound, screen arcing will do that but your UL taps should have a resistor i believe it is 470 ohms to help prevent that. You should check or replace those with 1/2 watt metal film type. My experience with that occasional pops is that it is usually comes from the electrolytic caps which tend to do that when they are pushed past their voltage limits. Or if they are old and because they can not tolerate the AC impulses like a new electrolytic. But, if you changed all the caps then the problem would most likely be elsewhere. You mention you had a bad tube socket. Could this have been your problem?
I also wanted to comment about rectifier tubes. The design of the amp takes into account the 5R4 as a rectifier. It is about the only tube you can use on this amp unless other changes are made. The indirectly heated rectifiers like 5ar4 which have the slow warm up also have a much lower voltage drop which results in much higher B+. If you sub in a 5ar4 your B+ will go up about 10%. This might cause problems. good luck, primo