BassInThePlace Posted October 27, 2008 Share Posted October 27, 2008 (edited) So I think I have DC leakage from my Spector pre-amp into my Trace that's causing some (minor) issues. When setting up the gain on the Trace, the 'clipping' LED [i]never[/i] blinks no matter how far I turn the knob, and the pre-shape button is not working as it should, ie I can always adjust the sound via the EQ instead of by-passing with the pre-shape button. So I can never properly set up my gain level - it's always just a guess..... The amp tech has given the head the all-clear vis-a-vis electronics etc, and suggested that maybe the pre-amp from the Spector is leaking DC and messing with the pre-amp in the Trace. I have still to try the amp with another, passive bass to see what the result is, but has anyone else had an experience like this? Btw, the amp is a MkIII Trace, and does not have a passive/active switch on the front. Ta. Edited October 27, 2008 by BassInThePlace Quote Link to comment Share on other sites More sharing options...
escholl Posted October 27, 2008 Share Posted October 27, 2008 The very, very, very first think that your bass signal is likely to encounter in the trace head is a capacitor, which is aptly named as a DC blocking capacitor. Try it with a different bass when you can. Has it always worked properly? Quote Link to comment Share on other sites More sharing options...
Kiwi Posted October 27, 2008 Share Posted October 27, 2008 I still think the amp is at fault. Quote Link to comment Share on other sites More sharing options...
BassInThePlace Posted October 27, 2008 Author Share Posted October 27, 2008 [quote name='escholl' post='316200' date='Oct 27 2008, 09:49 PM']The very, very, very first think that your bass signal is likely to encounter in the trace head is a capacitor, which is aptly named as a DC blocking capacitor. Try it with a different bass when you can. Has it always worked properly?[/quote] Well i've just bought it so I don't know if it's always worked. The amp-tech looked at it as soon as I got it and I only finalised the sale [i]after[/i] he gave it the all-clear. And he's a reputable chap from "Strung-Out Guitars" in Glasgow. I'm rehearsing tomorrow so i'll try it with a passive Fender Jazz and see what happens. Might need to get it sorted and bill the fella that gave it to me if it's the amp though. Shouldn't be a problem, but do I stand to damage my amp if I carry on like this? Quote Link to comment Share on other sites More sharing options...
escholl Posted October 27, 2008 Share Posted October 27, 2008 no, you won't damage it. did the amp tech know that there was a problem? or was he just looking at it to give it a general approval? unless he knew there was a problem, then in a quick look he'd have no way of knowing if something, such as a filter circuit or whatever else, might be not working. Components can look fine but not be fine, if you know what i mean. Also, i've never owned a trace so i'm just guessing here, does pre-shape actually force the eq into bypass, or does it simply engage a preset filter into the signal path, which can then additionally be adjusted with the EQ? does the sound change at all when you engage the pre-shape button? Quote Link to comment Share on other sites More sharing options...
ahpook Posted October 27, 2008 Share Posted October 27, 2008 it certainly sounds like the amp to me, sadly. as for whether the preshape button defeats the graphic eq...i've got the manual to the sm/smx series here and it's not mentioned there. the mkIII's are older though (??), so they could be different. Quote Link to comment Share on other sites More sharing options...
Kiwi Posted October 28, 2008 Share Posted October 28, 2008 I know the preshape doesn't defeat the graphic eq in the series 6 amps, you can have both on together if you wish. Quote Link to comment Share on other sites More sharing options...
escholl Posted October 28, 2008 Share Posted October 28, 2008 i'm actually wondering if there is anything wrong? IF the pre-shape button DOES affect the sound as it should, but doesn't bypass the graphic, then that seems to be the norm, at least on the later ones. and it's entirely possibly that trace have just put in a huge headroom on the preamp so only the highest signals will clip it. they're well designed, so really, it wouldn't surprise me if that was the case. try setting the preamp gain to about 7, adjusting the preshape, graphic, and other controls to your liking, wack the volume up and see what it's like? I should have mentioned in my first post, even if there WAS any DC leakage from your bass, it wouldn't matter, the amp is designed to filter that out anyways. I can't actually think of why an amp tech would tell you that was the issue, either. Not if they know anything about amplifiers...not trying to put him down or anything, but DC filtering is an essential part of all but the most pretentious hifi amplifiers. Quote Link to comment Share on other sites More sharing options...
BassInThePlace Posted October 28, 2008 Author Share Posted October 28, 2008 (edited) [quote name='escholl' post='316284' date='Oct 27 2008, 11:22 PM']no, you won't damage it. did the amp tech know that there was a problem? or was he just looking at it to give it a general approval? unless he knew there was a problem, then in a quick look he'd have no way of knowing if something, such as a filter circuit or whatever else, might be not working. Components can look fine but not be fine, if you know what i mean.[/quote] Yeah - that was the issue when I played it, so the amp went to the guy for that reason as well as a to give it a general "once-over". [quote name='escholl' post='316352' date='Oct 28 2008, 01:15 AM']i'm actually wondering if there is anything wrong? IF the pre-shape button DOES affect the sound as it should, but doesn't bypass the graphic, then that seems to be the norm, at least on the later ones. and it's entirely possibly that trace have just put in a huge headroom on the preamp so only the highest signals will clip it. they're well designed, so really, it wouldn't surprise me if that was the case. try setting the preamp gain to about 7, adjusting the preshape, graphic, and other controls to your liking, wack the volume up and see what it's like? I should have mentioned in my first post, even if there WAS any DC leakage from your bass, it wouldn't matter, the amp is designed to filter that out anyways. I can't actually think of why an amp tech would tell you that was the issue, either. Not if they know anything about amplifiers...not trying to put him down or anything, but DC filtering is an essential part of all but the most pretentious hifi amplifiers.[/quote] Well, the pre-shape does actually effect the sound as it should in my MkIII, but in the newer Traces (ie MkV) the only way to adjust the EQ post pre-shape is to toggle the EQ button. This way you get the pre-shape [i]and[/i] the EQ. This doesn't have the EQ toggle, so maybe you are correct in that dialing in the EQ will [i]always[/i] affect the sound no matter if the pre-shape is in or out..... Tbh, maybe it is just the headroom - in rehearsals i'm not even hitting 9 o'clock on my output and it's loud enough for the band. Sometimes [i]too[/i] loud actually. I'll mess with it tonight and see what I can find out. Cheers for the help. Edited October 28, 2008 by BassInThePlace Quote Link to comment Share on other sites More sharing options...
escholl Posted October 28, 2008 Share Posted October 28, 2008 [quote name='BassInThePlace' post='316523' date='Oct 28 2008, 10:42 AM']Well, the pre-shape does actually effect the sound as it should in my MkIII, but in the newer Traces (ie MkV) the only way to adjust the EQ post pre-shape is to toggle the EQ button. This way you get the pre-shape [i]and[/i] the EQ.[/quote] it may be then that this was only something implemented on the later traces then? [quote]This doesn't have the EQ toggle, so maybe you are correct in that dialing in the EQ will [i]always[/i] affect the sound no matter if the pre-shape is in or out..... Tbh, maybe it is just the headroom - in rehearsals i'm not even hitting 9 o'clock on my output and it's loud enough for the band. Sometimes [i]too[/i] loud actually. I'll mess with it tonight and see what I can find out. Cheers for the help.[/quote] If it's not causing a problem, i wouldn't worry too much, yes i suppose there is probably an "optimal" place to set the preamp gain etc but if it sounds good and there's no issues, it's fine. Just use your best judgment. Quote Link to comment Share on other sites More sharing options...
Merton Posted October 28, 2008 Share Posted October 28, 2008 When I had a Trace 12-band head (admittedly a 1999 model) I could push the input gain all the way up and not overdrive the preamp, this is with 18V active basses. So I think you'll find it may just have a massive amount of headroom! The preshape button isn't an EQ defeat, it sets an additional "preshape" curve to the EQ sliders. But you've figured that out already... Quote Link to comment Share on other sites More sharing options...
BassInThePlace Posted October 28, 2008 Author Share Posted October 28, 2008 [quote name='Merton' post='316609' date='Oct 28 2008, 12:22 PM']When I had a Trace 12-band head (admittedly a 1999 model) I could push the input gain all the way up and not overdrive the preamp, this is with 18V active basses. So I think you'll find it may just have a massive amount of headroom![/quote] Turn out that's all it was! First thing I tried when I got to the studio tonight was turning the gain all the way up. It only started clipping at the last, so the amp's fine and dandy. [i]Lots[/i] of headroom. Still think it's pretty unusual though as most, if not all, of the Traces I have used clip at around 2 o'clock with my bass. I'm not complaining mind you...... Quote Link to comment Share on other sites More sharing options...
budget bassist Posted October 29, 2008 Share Posted October 29, 2008 if i'd noticed this thread earlier, i'd have said if you can't HEAR clipping, then that's probably why the clip LED isn't illuminating. Really you should do this sort of thing with your ears and just use the the clip LED as a guide. If it sounds fine, then it's fine. Your eyes can trick your ears, trust me on this. I've been in the studio before playing with EQ settings and thinking i'm hearing subtle differences, then noticing the EQ is turned off! Just something to bear in mind. Quote Link to comment Share on other sites More sharing options...
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