Harbinger One - less than lush and barely unity gain.

[MAO]

Finished up a Harbinger One, seems to be working correctly but I'm only getting about unity gain with volume maxed and the overall sound is less than lush. Also, the vibrato is almost un-noticible at slower speeds, sounds ok at fast speeds though.   

I used the recommended lamp and photocells per the 2015 doc, with a 3/4 inch copper cap as the shield, tried with and without being lined with aluminum foil. Lined sounds better. The photocells are flat against the board.

Cant seem to bias in an even warble or one that satisfies, although there appears to be a lot of room to adjust both gain and offset. The lamp can get very bright with gain adjustment. (much brighter than the smaller of the two recommended lamps) The offset can adjust the lamp to turn out or stay dimly lit as it fades out.

The only intended change to the circuit is a dual 100k audio pot, instead of the dual 100kc, which I wired in reverse by flipping both lugs 1 and 3 making it a "slow" pot rather than "speed" pot. All other part values are stock.

Powered with 9V and LT1054.

The flasher LED (diffused RED 3mm) does not light up on slower speeds, wondering if that is normal operation or possibly related to the less than spectacular sound and volume.

Transistor Voltages: (all stock parts)

Q1
1.03
1.45
1.85

Q2
1.56
1.8
4.4

Q3
3.8
4.4
13.6

Q4
5.1
5.5
17.5

Q5
4.5
5.13
13.05

Q6
17.53
5.25
4.7

Q7
4
4.7
4

Q8
5.13
5.53
17.54

Q9
4.5
5.13
13.06

Q10
6.4
6.9
17.5

Q11
7.4-9.5
6.4-8.9
15.18

Q12
6.6 - 8.9
7.0-9.5
15.18

Q13
3.8-4.9
0
10-11.5

Q14
17.54
.47
0

Q15
15.18
15-15.3
0

   

[MAO]

Need advice on how bright to set the lamp and how much it should dim from it's max brightness.

Here's a video showing the biasing range of the lamp and some comments/questions. (sorry for getting tongue twisted, tired)

Here's another with a sound clip. I guess it doesn't sound so bad on the faster speeds, but I'm not happy with the slower settings. Should I stand up the LDRs and point them at the lamp? 

[Strassercaster]

hey mike i just watched your two clips on the you. tube. I also used the sa13 for more speed. however in my opinion your bulb is way way to bright. mine is less than half that bright sounds amazing and looked great on an oscilloscope. my electrical engineer amp builder friend checked it before even hearing it. afterchecking it he said this should sound really good and it does. you should cut that brightness down so that even at its  rightest the filament is a yellow oragne not blinding white. correct me if i am wrong madbeaners but i fou d this sounds best when you keep the light down. when the light is low the ldrs have more resistence which adds to the depth imho. try that also when the light is bright like yours which is how. i started as well. the throb is too much . its a fine line i know but ill try to. make a video of mine for you. i jsed the ldrs with the metal case they say it doesnt affect the sound but it does keep them surrounded and with the pairing i did they all had higher resistence. check out MR madbean himself studying the MoJO vibe bulb bias here i found this and it was what i based my bulb bias after. bias it clean and have a gain pedal Handy it will suprise you how it sounds a lot deeper and chewier with some gain
http://youtu.be/qTDo4qEXj2E
watch this see how dim this bulb is. after watching this i zeroed in on it

[MAO]

Thank you! wish I had found that video sooner.

That bulb's brightness looks very similar to the smaller lamp I had originally used. I still have the smaller bulb but the board traces lifted when I swapped it for the larger 7371, don't want to risk doing more damage but I'm sure I can dial back the brightness with the current lamp.

I ordered the new ldrs primarily due to not having enough lead length to stand up my current ldrs,  unless I make new legs for them. I may give that a shot just to campare flat versus standing ldrs.

Won't get to check it out until next week though, but sounds encouraging.

Thanks again

[Strassercaster]

honestly i dont think standing them up made a difference. it was bringing the brightness down i. retrospec im pretty sure. just go with what you have for now you should be able to fet close if not all the way there.like i said the darker the bulb the higher the resistence and deeper the phasing from what i have learned. the 7371 is the one i am using and its great.

[Strassercaster]

So how is it coming along any luck?

[MAO]

Sorry for not updating this thread.

You were spot on about the lamp's brightness, dimming the lamp made a huge difference. Thank again!

I'm working on another one right now, going to try and incorporate Craig Anderton's envelope follower to control the speed knob with picking dynamics.