Members OverDriven Posted October 24, 2010 Members Share Posted October 24, 2010 Can someone with a 6505+ do me a favor? Plug a patch cable into the effects send and another one into the return, but don't connect the other end of either cable to anything. Turn the amp on with the effects loop engaged and play. The 6505+ effects loop is series, so when signal can't pass through the loop it should be completely muted. Guess what? It's not. A surprising amount of signal leaks through loud and clear. It's specially bad on the lead channel, but happens on both the lead and rhythm channel to varying degrees. I want to make sure this is typical and not something wrong with my amp. I'm pretty sure it's normal for the 6505+. Not sure about the 6505/5150 original, but I don't remember having this problem when I had one a few years ago. I noticed because I'm getting a strange phased type sound with digital effects in the loop. It's a common problem with parallel loops because the effects unit slightly delays the sound due to latency and when the signals recombine it causes phase cancellation at certain frequencies. It shouldn't be a problem with a properly designed series loop, but apparently the 6505+ doesn't have a well designed loop and it acts like a parallel loop that is set to about 90% mix at all times. Great, huh? If this can't be resolved then the amp is up for sale unfortunately. Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 5 mins... Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 5 mins... Thanks man! Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 OK, I can hear what you're talking about. However, I currently run a digitech digidelay in the loop and no problems. That said the 6505+ loop is flakey in nature. I did my homework and this is my solution: 1. Run the effects loop cables straight down and under the cab out to your pedals. You want to get them away from the source of electrical interference. 2. I have been told that using balanced patch cables in the loop is a big solution. I have tried this and noticed no discernable difference. That said, I'm sure someone must have noticed it plenty as I've read it enough times. 3. This one helped me. Avoid using the same plug socket for the amp and you pedal board. I had a single 4poing power strip that I plugged everything into. When I changed to plugging the amp into its own socket, it improved the noise aspect dramatically. I have to say though, it doesn't sound half as bad as you're suggesting which would make me wonder if you don't have a problem? I've never noticed any digital phasing on the 6505+ only noise which I need to invest some bucks into a gate for. I have also read a few times of relay problems which can mess with the loop bigtime. Aside from that, let the amp warm up for a good 15 minutes before play. I started doing this and it does seem to be more responsive if you do. Playing from cold, the amp doesn't really seem to get that dynamicness to it... Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 So you can hear the signal bleeding through though? From what I understand, it occurs because the tube used for the effects loop is shared with the preamp. Half the tube handles the loop and the other half is a gain stage. Sometimes half is the send and the other half is the return. Either way, what happens is that one side of the tube is picking up the signal from the other. I'm wondering if a better tube in the effects loop slot would help. I'll try that tomorrow. Thanks for your help! Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 So you can hear the signal bleeding through though? From what I understand, it occurs because the tube used for the effects loop is shared with the preamp. Half the tube handles the loop and the other half is a gain stage. Sometimes half is the send and the other half is the return. Either way, what happens is that one side of the tube is picking up the signal from the other. I'm wondering if a better tube in the effects loop slot would help. I'll try that tomorrow. Thanks for your help! I can hear a slight bleed through... there's no volume drop or anything, however that's with the loop engaged. With the loop off, there's nowt. Even if I wiggle the dangling cables. It may well be a tube in that case; I have to say I haven't been all that impressed with the Sovtek tubes for a while. I'm waiting until my Pod HD turns up to decide if I'm keeping my peavey or not. If I am then it's getting retubed. I have read some real horror stories regarding the loop on the 6505+. Thankfully, I've yet to run into a single issue although the amp is only a few weeks old. I would also caveat about the balanced cable thing. There are people who seem utterly convinced on that one. I noticed no difference but the only time I've had it up loud was one rehersal where I ran it sans effects of any description. So it may be different up loud. Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 How are people running balanced cables in the loop? It just accepts a standard 1/4" mono cable. Are they plugging stereo cables in or something? Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 How are people running balanced cables in the loop? It just accepts a standard 1/4" mono cable. Are they plugging stereo cables in or something? From what I can see, yes. I'm not sure why they think it helps, but I didn't argue. Alls I can say is I didn't notice any difference. I still use two planet waves blue label cables for the loop and another for the input. I've been happy with those cables since my Engl Powerball days. Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 Speaking of which, I've never tried him, but Jerry P is meant to be some kinda genius on these amps. I got a lot of my info from ultimate guitar and the andy sneap forums too, so may want to check them out too. What pedal are you trying to run and what problems are you getting? Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 Speaking of which, I've never tried him, but Jerry P is meant to be some kinda genius on these amps. I got a lot of my info from ultimate guitar and the andy sneap forums too, so may want to check them out too. What pedal are you trying to run and what problems are you getting? I'm running a TC Electronics Nova System. It's a killer effects unit, but when I use it with the lead channel of the 6505+ the effects loop bleed through is mixing with the effected signal and causing phase cancellation, which makes the sound somewhat metallic and hollow. It's the exact same problem you would get if you ran a digital effects unit with a parallel loop that was set to 90% wet. I've just done some more reading and it looks like a good tube in V3 (the effects loop slot) could fix the problem since certain tubes have less crosstalk between the triodes than others. I think I must have a tube in there with lots of crosstalk. I'll post tomorrow after I try some other tubes in that slot. Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 I'd be interested to hear about what you use. I have a Pod HD500 coming, concerned that the loop in the 6505+ will fail me now :s I shall, of course, report back! Link to comment Share on other sites More sharing options...
Members Shask Posted October 24, 2010 Members Share Posted October 24, 2010 Yep, with the original 5150 I made a thread like 7 years ago, and people pretty much said the same thing. I just never made a big deal out of it, since I really don't use the loop.... Link to comment Share on other sites More sharing options...
Members Nerine Posted October 24, 2010 Members Share Posted October 24, 2010 This is, I think, a prime example of the argument of having invested a little more R & D in the amp as was being "discussed" in that other thread. Types of problems like this can sway sales from the more discerning player IMO. Link to comment Share on other sites More sharing options...
Members Toshiro Posted October 24, 2010 Members Share Posted October 24, 2010 I'm running a TC Electronics Nova System. It's a killer effects unit, but when I use it with the lead channel of the 6505+ the effects loop bleed through is mixing with the effected signal and causing phase cancellation, which makes the sound somewhat metallic and hollow. It's the exact same problem you would get if you ran a digital effects unit with a parallel loop that was set to 90% wet. I've just done some more reading and it looks like a good tube in V3 (the effects loop slot) could fix the problem since certain tubes have less crosstalk between the triodes than others. I think I must have a tube in there with lots of crosstalk. I'll post tomorrow after I try some other tubes in that slot. This explains a lot, my jam buddy has that same setup. He's having issues with the gate on the Nova, and that would cover why. Gonna have to test some different tubes in that slot the next time he's over. We were going to do the bias mod to it, maybe there's an effects loop mod? Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 Update: I fixed it for the most part. I swapped different 12AX7s into the slot that runs the effects loop. Some were even worse, but I found an old Mesa tube that cut the bleed down significantly. It's still there, but it's much quieter and it only gets louder as you turn up to about 1. Past that it maintains the same level. So with the amp at lower than TV volumes, I'm still getting a little bit of phasing, but anything past that and the output volume is so much higher than the bleedover that the effect is negligible. I'm happy. So now I can stop worrying about the setup and start using the effects. I just tried the harmonizer in E Phrygian and . I'm in love. Link to comment Share on other sites More sharing options...
Members satannica Posted October 24, 2010 Members Share Posted October 24, 2010 Awesome news! I wonder if putting something like a 12AT7 in that slot would solve the issue totally in that case as it's lower gain? Link to comment Share on other sites More sharing options...
Members OverDriven Posted October 24, 2010 Author Members Share Posted October 24, 2010 Awesome news! I wonder if putting something like a 12AT7 in that slot would solve the issue totally in that case as it's lower gain? I was thinking about that actually, but I don't have one on hand. I think it might mess up the loop volume though. I'll try it when I get one. Link to comment Share on other sites More sharing options...
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