No. 8 Wire Posted November 29, 2016 Share Posted November 29, 2016 I have a Line 6 Studio 110 ([url="http://www.musiciansfriend.com/amplifiers-effects/line-6-lowdown-studio-110-combo-bass-amp"]http://www.musicians...-combo-bass-amp[/url]), its served me well over the years as a handy practice amp round the house. However, over the last year it's developed a bit of a hiss, which I have kind of ignored as it doesn't get used for recording or gigs. However this has got a lot worse lately and combined with that, the synth bass 'channel' on the amp just produces fairly random noise now. Now the hiss is quite weird, as it is not constant, its only there when a note is played. Its the sort of hiss you might get when a noise gate is being used. I've taken the front panel off, hoping to clean the pots as a possible source of noise, but the pots seem to be sealed units (see picture). So I have no idea how to clean these - sing out if you know a way to clean these. It was a long shot anyway as there is no scratchiness when moving them, but then maybe digital amps react in different ways to dirty pots? [url="https://drive.google.com/file/d/0BxcVuuI82HsBNVE3blZOQ0hKZEU/view?usp=sharing"]https://drive.google...iew?usp=sharing[/url] So, unless I can find a way to repair the preamp, which seems unlikley, I was thinking of turning the 110 into a little powered cab by keeping the power amp and running a 1/4 socket directly into the poweramp. Then I could run my pedal board (with preamp) straight into it. Would this work? I can't figure out how the volume of the power amp is controlled, will it be controlled solely by the input volume from the preamp? Here is a picture of the input to the power amp: [url="https://drive.google.com/file/d/0BxcVuuI82HsBUDN0d2JLdlhCckk/view?usp=sharing"]https://drive.google...iew?usp=sharing[/url] In schematic form: [attachment=232933:Untitled-1.jpg] This is the full service manual for the amp, it contains the schematics as well on the first two pages. [url="https://bmamps.com/"]https://bmamps.com/[/url][b]Schematics[/b]/[b]Line[/b]_[b]6[/b]/[b]Line[/b]_[b]6[/b]_low_down_[b]studio[/b]_[b]110[/b]_sm.pdf Another 'guts' shot: [url="https://drive.google.com/file/d/0BxcVuuI82HsBTC0tbXhqanQyV00/view?usp=sharing"]https://drive.google...iew?usp=sharing[/url] [b]Any help appreciated, Dan [/b] Quote Link to comment Share on other sites More sharing options...
Twincam Posted November 30, 2016 Share Posted November 30, 2016 Is it definitely a hiss or a hum? Have you checked any connection blocks or grounding wires are secure. The thing is how do you know its the preamp? It could be a power section issue. Although since your getting an issue more using the synth it would suggest its indeed somewhere in the pre fx section. Quote Link to comment Share on other sites More sharing options...
No. 8 Wire Posted November 30, 2016 Author Share Posted November 30, 2016 [quote name='Twincam' timestamp='1480473457' post='3184712'] Is it definitely a hiss or a hum? Have you checked any connection blocks or grounding wires are secure. The thing is how do you know its the preamp? It could be a power section issue. Although since your getting an issue more using the synth it would suggest its indeed somewhere in the pre fx section. [/quote] I'm just going through all the connectors today, and run compressed air and contact cleaner over all jacks etc. It's a good point about the poweramp, I'll test through the preamp out, headphones and DI to see if the same fault occurs. Once I've cleaned and reassembled. There's no power amp in or fx loop to isolate the power amp unfortunately. I'll record some audio once it's back together. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted November 30, 2016 Share Posted November 30, 2016 Well sometimes it's good to try to help, that site with the circuit diagrams on is great, thanks. Unfortunately there's not much I can offer. The volume and tone is all handled electronically so you'd need to break in to the circuit after the master volume. On the plus side the noise is unlikely to be coming from the pots as they aren't directly handling the signal. My guess for the noise is that it is coming from the DSP as it is only happening when you play. Is it affected by which amp sims you use or the opto comp? Quote Link to comment Share on other sites More sharing options...
No. 8 Wire Posted November 30, 2016 Author Share Posted November 30, 2016 (edited) [quote name='Phil Starr' timestamp='1480494615' post='3184755'] Well sometimes it's good to try to help, that site with the circuit diagrams on is great, thanks. Unfortunately there's not much I can offer. The volume and tone is all handled electronically so you'd need to break in to the circuit after the master volume. On the plus side the noise is unlikely to be coming from the pots as they aren't directly handling the signal. My guess for the noise is that it is coming from the DSP as it is only happening when you play. Is it affected by which amp sims you use or the opto comp? [/quote] Phil, thanks for the input. Yes, the noise is worse with the grind and synth Sims. Now that you mention it, it is worse with the opto comp turned up. If I converted it to a powered amp, would a bass preamp pedal (dha vt1 eq) have enough output to drive it? The line 6 preamp seems to have a Vpp Max output of 24.6. Presumably a DHA preamp wouldn't get near that? Happy for some education here as know nothing about amplifiers. Edited November 30, 2016 by No. 8 Wire Quote Link to comment Share on other sites More sharing options...
No. 8 Wire Posted November 30, 2016 Author Share Posted November 30, 2016 Update: The power amp is definitely not the problem. Tried out two preamps straight into the Audio in on the power amp and got some clean sound. Preamps: 1. DHA VT1 EQ. I was a bit worried after using this one, my DHA pedal is faulty anyway and produces background noise, at low volumes its not noticable and actually produced a very pleasing clean tubey sound. However, even with everything maxed on the DHA it couldn't push the power amp to max volume (as perceived by my Mk 1 ears) and at any volume higher than bedroom noodling volume the noise from the DHA was pretty bad. 2. Line 6 Pod XT Live. Bit of a revelation, absolutely zero noise at any volume and seems to get close to max volume with the channel volume and output level adjuster maxed out. After the test I found a schematic for the pod on the same site as above and it showed the Pod has a max output of 24 Vpp. So that is pretty close to the 110 preamp output. Of the two, I think I liked the sound of the DHA better - although I've just realised I did the test with the speaker sim engaged on the POD, so may need to revisit that. Would love to get the DHA working noise free with it though as it would make a cracking little hybrid practice amp. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted November 30, 2016 Share Posted November 30, 2016 I've no information about any of the gear you are using, so you'll have to look it up for chapter and verse. This is a kind of primer/rule of thumb about pre amps. I hope it's enough to help you get things sorted. It's all about gain. A bass gives out around 1/1000 of a volt. A lot of pre amp circuitry operates at around 1/10th of a volt (a gain of 100 in other words) most power amp stages take about a volt so there will be another gain stage of about 10 somewhere. Obviously these are approximate figures and different manufacturers have used other options. Obviously you don't want to go into distortion and the Vpp (volts peak to peak) is just an expression of how high that stage can go before distorting, it doesn't say anything about gain. Some fx are designed to go into the guitar input and give out a few mV, most go into the fx loop at around 100mV, 1/10th of a volt. Others might be capable of driving a power amp direct. So, my guess is that you need something that gives you a little extra gain of about x10. For experimentation purposes a PA mixer will give you all the gain you need, beg, steal or borrow one of those, once you have the sound you wnat you can then look for a cheap pre=amp stage that will give you the little bit of extra gain you need. There will be fx capable of driving a power amp directly though, but you need clean gain not something that is designed to distort at higher levels. 1 Quote Link to comment Share on other sites More sharing options...
No. 8 Wire Posted November 30, 2016 Author Share Posted November 30, 2016 Thanks Phil - helpful stuff, although I may end up doing this by trial and error. Another idea I had was to bypass the DSP and therefore utilise the Line 6 preamp without the digital processing. Not sure if I can just bridge the Rout and Rin on the AK4556 ADC (and then disconnect the ADC. Would lose master volume control I'm guessing. Quote Link to comment Share on other sites More sharing options...
Bass Wielder Posted April 24, 2021 Share Posted April 24, 2021 Hi sorry to resurrect an old post.... I now own a line 6 studio 110 and have to say I’m having the same hiss noise. My thoughts lead me to this here, which is to bypass the preamp section or at least the effects and use the power section. Can I humbly ask for an update on if you guys succeeded to do this or something like this? Quote Link to comment Share on other sites More sharing options...
Bass Wielder Posted January 20, 2022 Share Posted January 20, 2022 🤷🏽♂️ Quote Link to comment Share on other sites More sharing options...
nekomatic Posted January 20, 2022 Share Posted January 20, 2022 If you tag @No. 8 Wire they should get an alert about it, in case they aren’t subscribed to the quite old thread any more. In any case it sounds as if it should work, as long as you can feed a hot enough signal to the amp’s ‘audio in’. Quote Link to comment Share on other sites More sharing options...
No. 8 Wire Posted January 30, 2022 Author Share Posted January 30, 2022 On 25/04/2021 at 00:27, Bass Wielder said: Hi sorry to resurrect an old post.... I now own a line 6 studio 110 and have to say I’m having the same hiss noise. My thoughts lead me to this here, which is to bypass the preamp section or at least the effects and use the power section. Can I humbly ask for an update on if you guys succeeded to do this or something like this? Sorry, haven't visited the site for... well about 10 months! In short, yes, I succeeded. My 110 is in storage right now but I can remember the basics. Internally the preamp and power amp are two very separate units. Its fairly easy to trace the power amp input, disconnect it and connect a 1/4 input jack. Note that the power amp is 'dumb', it is just on or off, no master volume etc. So whatever preamp you use will need enough output to drive the power amp to get volume. I used an old line 6 xt pod live which has a preamp mode and also a DHA valve preamp which could do the same. Any pedal will probably do it, but you might not get the full output. Mine might be out of storage in a month or so, i can take a pic of the internals then if you need it. Quote Link to comment Share on other sites More sharing options...
Bass Wielder Posted January 31, 2022 Share Posted January 31, 2022 4 hours ago, No. 8 Wire said: Mine might be out of storage in a month or so, i can take a pic of the internals then if you need it. Thanks for your reply.….and a pic would be extremely helpful and appreciated. cheers Quote Link to comment Share on other sites More sharing options...
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