Triple SHO

[slacker]

To expand a bit on what Doug said. At the minute you're basically applying huge amounts of gain across all the audio frequencies, so the circuit has plenty of bass it's just that all the other frequencies are equally loud so they are masking the bass. The circuit probably can't produce much more amplification that it already is so you can't just boost the bass some more. Even if the circuit could all that would do is increase the clipping in the bass frequencies it wouldn't necessarily make it sound louder.

To make the bass sound louder you need to reduce the gain of the higher frequencies, which is where the tone shaping that Doug was talking about comes in.

Hope that makes sense

[Gus]

With multi gain stages sometimes you need to reduce the bass in a stage(s) and the correct order of HP and LP and gain is important.  Think about how sound can "bunch up" in the mids and highs with clipping and bending lower frequency waveforms

[WGTP]

I think the key to more bass, as indicated, is to alter the tone stack such that the mids and highs are reduced and the bass "seems" to get a boost.  Have you messed with the Duncan Tonestack yet?   

[deaconque]

I've tried changing the filtering b/t the stages using various HP and LP filters and they all gave me the same basic overdrive sound (as I've mentioned).

As I already mentioned in the members thread you will probably need some attenuation/filtering between the stages to get the sound you want.

Too much gain, not enough headroom, ineffective gain control, sterile sound, etc- it's all related to the stuff I mentioned.

It's not about lowering the gain. It's about contouring the frequency response so you get the gain in the frequency bands that sound good.

This isn't really a whole lot of help.

So now you have discovered (as others already have) that slapping three gain stages (boosters) together in a row does not make for a pleasing distortion sound. So now you have to put some work into and learn what does make a pleasing distortion

Dude- You've posted basically the same idea 3 times now. I've made suggestions to improve it twice at this point. If you don't read the tips/mods material Aron has had posted elsewhere on this site for years and try any of the ideas- there's not much anyone can do to help you.

The definition of insanity is repeating the same behavior over and over and expecting different results...

Comments like this don't really help at all and are completely unnecessary.  Being condescending towards someone who is trying to learn this type of stuff is the opposite of, what I thought, this forum was here to provide.  Doug, if this thread bothers you that much the please don't bother "helping".

[deaconque]

Gus and slacker- Thank you for clarifying what was said.  I understand a little bit better now.

WGTP-  I have used the Duncan Tonestack.  The tonestack at the end of my schematic is pretty good to my ears though.  It gives me a pretty usable range of HP and LP and I'd like to use it as it is if possible.

[DougH]

Look at the BSIAB schematic and here for tips on how to do interstage filtering:

http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques

[petemoore]

2.  Although it sounds good, it's sound is a little on the sterile side.
 Who said it and I forget exact wording...worked something like:
 If all frequencies were equal, and everything that multiplied them many times repeatedly was perfectly equal, a very even distortion type sound could be had if:
 Distortion itself didn't do so many wierd things to frequency Vs. Amplitude.
 Any uneveness in frequency amplitude, multiplied so many times...no matter what the source, certain frequencies will be clipped more early, others may be compressed [such as loss of bass because the input current becomes much too high].
 Although the transistors themselves do contribute to frequency Vs amplitude, and can be manipulated to some' degree to attenuate the desired frequencies...if the desired frequencies happen to be 'midrange first', some other means of attenuating those frequencies should be sought.
 And any 'manipulating' of transistor frequency inadequacies [which most transistors are designed to not have], will almost certainly be accompanied by some 'other' characteristic, such as distortion [sterile, desired or harsh].
  Not to say the Ge FF doesn't use transistor 'inadequacy' [limited HF gain] to a great [if small] effect, beyond that...
 everytime [except with low voltage Jfets] I seriesed many gain stages together, noticable differences in gain at certain frequencies was noticed..such as HF's multiplying themselves right 'through the ceiling'...without some taming the sound can be very harsh.
 Yupp...some of the LV Jfet experiments did a nice LP filter effect, the gain on the HF's naturally and nicely rolled off as signal strength increased...useful effects like that can be cool...   
  Not to say filtering is always 'required', but like Doug and others [me too] suggest, inter-stage filtering is the best [only?] option for reliable/controllable frequency gains on such a multi-gain-stage circuit such at this.
  I do like and use the 'sprinkle filters' over the entire circuit, however which a small handful of capacitors, and a couple test-clip-wires, some signal to ground shunting of various amounts of HF's [try it early on or wherever you want, sample various values, probably .01uf - 100pf.].
  For a quick bass filter, try an added small input cap, can be added [in series with existing input cap] to the input cap offboard wire.

[DougH]

deaconque:

I am not intentionally being condescending. I do get frustrated at times when I try to help people and they seemingly don't try the ideas I suggest but keep asking the same questions. This thread has been going on for a while and originally was part of one or two other threads. If I missed where you did try my suggestions unsuccessfully and I misread you, I apologize. There is no harm intended with any of my posts. I like to see people trying things and trying to learn. Sometimes I like to drop hints instead of spelling things out. People learn more when they have to reach a little.

Look at the Booster2.5 or BSIAB for ideas on interstage filtering, especially the 470k/470p.

Look at amp schematics and/or the ROG JFET circuits for ideas on how to tune the source circuit.

As others have mentioned, you usually want to some "frequency shaping" in the early stages, such as cutting bass for example. Then roll off highs in the later stages to balance out treble/bass and smooth the distortion harmonics. Don't worry about maintaining the ridiculously high Zin of the SHO in the latter stages. That is only significant with a weak high Z of a guitar signal. The early stages will drive enough current to make 5M Zin unnecessary- unless you like a lot of noise.

[deaconque]

Doug- Thank you.  I do appreciate that you are trying to help.  I understand that it can be frustrating at times.  I wouldnn't exactly consider myself a noob to building but I am new to learning which component do what.  I know about RC Filters but what exactly does the 470k/470p in parallel do.  Most RC filters have one component going to ground, correct?

[DougH]

I know about RC Filters but what exactly does the 470k/470p in parallel do.

Check the simple mods page I linked above. Look for "low cut filter". You will see fixed filters like this a lot in marshall amps. The series resistor attenuates the signal (it is usually the "series" part of a voltage divider, with say, another 470k to ground). The 470p cap "leaks" highs through it unattenuated.

[petemoore]

  Scope helps, even pics of scope...
  Good mosfet page here:
http://www.fairchildsemi.com/an/AN/AN-7500.pdf
  Different wavelengths [ie like the fat, loose string being heavy, it pushes hard, but swings slowly = longer wavelength] amplify differently. 
  'the MOSFET operates at much higher speed than its bipolar counterpart'.
  When multiplied by a gain stage, then the product of that is multiplied again [the next, seriesed gain stages = a large number that the input signal is multiplied by], certain wavelengths will hit an extreme parameter [such as nearing or trying to surpass a power supply rail potential] before other wavelengths do. This can mean by the time the mids get 'wierdness-wobbles' [distortion] added to their waveform, the bass or treble might be slamming the rail, going into and out of saturation for long periods [ie instead of just 'trimming the peaks', the waveform becomes less recognizable because the whole top 1/2 is lopped off. That kind of heavy lopping of certain frequencies can cause distortion to the HF's to sound 'sterile' or harsh, or make bass sound ill-defined.
  Capacitors used as LP and HP filters allow shaping the amount of gain applied to high and low frequencies.
  With gains preset to chosen level..
  ..or allowing an interstage gain control to control the amplitude of all relevant frequencies ['allpass' attenuator]..[looks like volume control between gain stages], and combining these with HP and LP filters, the amount of boost added to high frequencies, as well as the amount of distortion 'added' to the highs, can be controlled by LP filtering...where you choose to...do it later and allow distortion to be generated in the highs, cut most of the highs at the input and less distortion will be generated in those frequencies, same can be said for lows and mids, capacitors and other gain or gain/frequency controlling may be desirable.
  With three mosfets sho-n, some gain/frequency controls would probably render a smoother sounding distortion.