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Author
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Topic: does "Sensitivity"=Post-gain? why keep it high?
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Nicholas Dedring
Member From: Brooklyn, New York, USA
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posted 21 June 2003 03:11 PM
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I have a Session 400 LTD, and there's a "Sensitivity" knob... is this the same thing as a post-gain knob on other amps?Also, I've heard a bunch of times that you should keep the post-gain/sensitivity really high (around 3 o'clock); why is that necessary? Is it a clipping issue? Is it okay to have it around the same clock position as the initial gain control? I find that I hate how brittle the sound is with the sensitivity up so high. I'm asking, mainly because I finally tinkered with it some, and found the sound I was looking for (aside from my clumsy playing) with that control dialed much further down. Will it do any harm, I'm wondering. Thanks for any advice on this...[This message was edited by Nicholas Dedring on 21 June 2003 at 03:13 PM.] |
Ken Fox
Member From: Ray City, GA USA
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posted 21 June 2003 03:47 PM
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In the early Session 400 it was the equivalent of a master volume in a SIlverface Twin. It was stated that it was to set the sensivity of the power amp. Well, that is where it was, right after the preamp stages and before the power amp. Of course max clean headroom would be with it all the way up. I used to do that, but have found I would rather work the preamp stages a little harder for a warmer sound.
Use your ear and set it for what pleases you! |
Nicholas Dedring
Member From: Brooklyn, New York, USA
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posted 23 June 2003 09:01 AM
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bumpMike Brown, are you out there? |
Bill Terry
Member From: Bastrop, TX, USA
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posted 23 June 2003 09:53 AM
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I don't think the Sensitivity was ever intended to work like a master volume, although it behaves a bit like that.From the Session 400 Manual:
quote:
The master sensitivity control(11) is a unique innovation which allows the player to "cut" or "boost" sensitivity as he desires. This allows the musician to cut out noise for a perfectly quiet performance during recording sessions.
It was designed to maximize SNR, or get the actual musical signal as far above the noise floor as possible in a recording environment. However, nothing is 'free', you sacrifice some power amp 'gain' for quieter operation. A by-product is you do end up driving the preamp a little harder to get to the same volume, as Ken mentioned. That can be used as an advantage to alter the tonality, it won't hurt a thing. If Brad Sarno is reading this, we exchanged a couple of emails about how the sensitivity is generally not well understood by the user, but is a really useful feature in the studio. Might be a good piece of info for his Session 400 Geek page.
[This message was edited by Bill Terry on 23 June 2003 at 09:57 AM.] |
Ken Fox
Member From: Ray City, GA USA
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posted 23 June 2003 05:01 PM
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If it looks like a duck and talks like a duck.....I am looking at the schematic for a Session 400/LTD and what we have is 50K pot that merely dumps signal from the preamp to ground. It is noted as the "Master" in the schematic. The only thing unique is that there are two more transistors after that stage to allow the reverb signal to be mixed in with the signal that has been attenutaed by the "master" or "sensitivity" control. Therefore the reverb setting is independent of the "master" pot. Setting the sensitivity of a power amp is merely adding a volume control in front of it, whether it be a passive device (pot) or an active device (negative feedback to a gain stage of a preamp IC for example)! |
Brad Sarno
Member From: St. Louis, MO USA
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posted 23 June 2003 05:28 PM
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Yea, what Ken said. It's really more simple than the old manual implies. It's purpose was to bring down the preamp noise before hitting the power section, thus quieting the amp (increasing the S/N ration) in low volume situations (home/studio). Like Ken said, on the schematic they label that control as "master". The Session does behave uniquely in that you can actually get creative by driving the volume a bit harder and bringing down the "Sensitivity" to get a little bit of compression. The j-fet loaded preamp section will act a bit like a tube amp when driven. So I guess to sum up the thread a bit, yes, the "Sensitivity" control IS a "Master" volume control. ------------------
Brad Sarno
Blue Jade Audio Mastering
St. Louis |
Ken Fox
Member From: Ray City, GA USA
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posted 23 June 2003 06:39 PM
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It is a cool amp for sure! The sensitivity is something I only recently learned to appreciate! For years I kept it wide open and the channel volume down. With a Tele, I set the channel at 7 or 8 and it really warms up nice. I have had a lot of people tell me "that is a cool sounding tube amp, what model is it?"! [This message was edited by Ken Fox on 23 June 2003 at 06:40 PM.] |
Bill Terry
Member From: Bastrop, TX, USA
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posted 23 June 2003 09:12 PM
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But don't expect to set the Sensitivity on 1 or 2, set the preamp wide open and get a screaming lead tone. It doesn't work that way, and wasn't intended to. THAT is what most rock and blues players expect a master volume to do. Semantics...  |
Ken Fox
Member From: Ray City, GA USA
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posted 23 June 2003 09:30 PM
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You are totally right there. This amp is made for clean playing! One of the most interesting reviews I read about this amp was by a hard-rocker on Harmony Central. He loved it. Here it is:"Features: 10
This amp was bought used from a shop. I don't kow a ton about it. However I do know that this amp is a solid state amplifier. Some of its features are a footswitch (channel changing, and reverb) 2 inputs. A external speaker output. Power there is a whole hell of a lot of it. 200 watts rms (internal) External 400 big bad watts. Alot of range and adjustabilty. it is a single 15 inch speaker. If you like a thick sound this is the amp. Sound Quality: 10
I use a few guitars with the amp. I have a SRV strat, a Ibanez Iceman 300, and a ESP Kirk Hammet signature. I play in a band that is mostly a metal band. I play alot of lead mixed with rhythm this amp handles both very well. On a personaly level I strive to be the next hendrix ha ha, being serious though I play alot of blues and it is great for that as well. It is a very loud powerful amp. however it sounds good at many different levels. Clean channel stays clean even when trying to break the windows. I run the guitars through a series of pedals and a digitech rp6 pedal board. Reliability: 9
It is a workhorse, count on it too work every show evertime the power switch is flipped open Customer Support: N/A
Overall Rating: 10
I rate it a 10.. I have played crate, vox, mesa, sun, hugh and kettner, and marshall. I love this amp it is a dependable loud amp"
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