DOD 280 again, less bass controlling comp amount ?

[petemoore]

  Being as there is no DC blocking cap between opamp IC1a output and opamp IC1b -input leaves C4 and C5 as possible values to remove some of the lower frequencies control over gain reduction.
  http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=45&Itemid=99999999
  The bass notes from these HB's drops gain nicely, it is a cool effect, often overpronounced.
  I will install a smaller C6 and perhaps a parallel 22uf bypass switch.
  The circuit is rather sluggish in general, this is probably due to the LDR used.
  Is this or some other way a possible way to introduce a high pass filter feeding the LED lighting portion of the circuit so that bass notes don't light the LED so brightly ?
 

[mills]

I just built a 280A, and socketed C4/5 so I could try to change the amount the bass affected compression...  haven't actually tried different values yet.

I probably don't know enough to help with your question, but I'm going to jump in and ask a related question if thats ok.

You're thinking about changing C6, would that be to make it less sluggish rather than to cut the lows lighting the LED?  Or does C6 also affect which frequencies the transistor amplifies and change frequency response as well as timing?  I used a VTL5C10 instead of the 2 the schem called for and replaced r10 with a 1.8Kresistor and a 10k trimpot.  I don't know if its r10 or the photocoupler, but theres some settings on the trimpot that make things significantly less sluggish.

[petemoore]

You're thinking about changing C6, would that be to make it less sluggish rather than to cut the lows lighting the LED? 
  I read the thread Mark H. wrote on the 280.
  S~imple compressor is a gain stage that happens to have a gain control.
  Or does C6 also affect which frequencies the transistor amplifies and change frequency response as well as timing?
  C6 fills up and empties, controlling the ramp up/down rate, a smaller capacity fills and empties faster.
   I used a VTL5C10 instead of the 2 the schem called for and replaced r10 with a 1.8Kresistor and a 10k trimpot. 
  I used 'an LDR' and red LED, the mod you describe I think is going to be a good one, however, 4k7 + 5k pot is probably how I'll wire it, seeing how the LED has no trouble lighting and reducing the R of the LDR, plenty of gain reduction as it sits, I think it could use a more 'mellowed out' gain reduction.
  I don't know if its r10 or the photocoupler, but theres some settings on the trimpot that make things significantly less sluggish.
  It would seem what you're experiencing would be related to..the LDR has a quicker time of it when it's resistance sweep is limited, that's what your R10=variable resistor mod would do.
  Another possible or impossible?..mod the emitters of the 2 transistors, put a frequency control on them, small emitter resistors and 'small-ish' AC bypass caps would 'up the gain for higher frequencies...whether this would 'upset the apple cart' I don't know.
  Mark did point out how the shooting match is a 'balancing act' [my words], start with C6 and adapt further at risk of upsetting the apple cart after that.

[petemoore]

  I like that it's presently an ''upset apple sound''. The compression times allow control of 'longer volume/gain setting periods which lend useful rythmic contributions to certain musical passages and play style.
  I can turn the volume down with light bass notes, then hammer-sweep the high strings for heavy attack / pull-back effect, pretty neat, but when the tempo and style of attacks change, the longer/deeper compression becomes more or less arythmic, less useful.
  So, I'll start with C6 values on a switch, but suspect some LF attentuation before the second opamp and transistors would go a long way to reduce somewhat, and provide a better balanced application of compression across the relevant frequency band for guitar.
  I'm just not sure where to start doing it...fairly simple jig, I may have to build another perf-mod-job and see what the transistor input capacitors or emitter R/C modifications yield for frequency = X lighting effect of LED.
  It's too bad a capacitor can't be used directly on the LED.