Every harmonic perc I make barely goes above unity with everything dimed

[Bandwagonesque]

         Hi everyone and apologies for starting a new thread to beat a potential dead horse but hope this may help someone in the same boat.  I've been trying to fall over the harmonic percolator for a bit now with bread boarding two versions of the circuit so far and I can't seem to gel with it due to not having enough volume on tap. Even with everything dimed, it just sounds haggard. It seems that folks are having way more success with their builds and having enough volume to actually make the controls usable even with the diodes in play. Then again, i've read about people dealing with the same so i'm confused as to where to stand if this is normal for the circuit or if i'm just not cooking things right.
        My first breadboard attempt with all its mods and transistor swapping could barely get above unity volume (with diodes). I decided today to try again from the beginning with parts as close to the 'albini' values as possible (schematic attached, I did not implement the power filtering or diode symmetry pot, diodes right to grounds with no bypass). 1n695a' diodes, 2n404a at Q1 and 2n3965 for Q2, greenie 47uf cap, 100pF silver mica, 100uF tantalum and etc. It's all in there. I kicked it on and while it sounded better than my first attempt, the lack in volume was unfortunately still there. And ultimately just underwhelming really. I should state now that I haven't played any other HP before, just listening to hearsay and demo's but my expectations haven't been met. Without that volume on tap it's frankly anemic and strained and farty. Some modding of some values for trim pot biasing helped quell the fart and got it sounding nice but to try and goose more volume (raising the 4.7k to 10k)ultimately lead to nothing. I'm beginning to stand on the fence that this is just the way this circuit is with the diodes in play but wanted to ask here if this is the absolute or if my build(s) have been in error so far somewhere on the circuit (really doubtful, i've checked it all thrice and then some but who knows)...



Here are my voltages for Q1 and Q2 as they stand now:
2n404a
hFE: 38
C: 3.55
B: 3.82
E: 3.87

2n3965
hFE: 284
C: 5.85
B: 3.91
E: 3.73

and here are the forward voltages for the 1n695a diodes
.290

(don't think it matters but guitar has high output passive pickups into a tech 21 ss amps clean channel. really don't think its the pedal not liking the rig)


Everything seems relatively normal but does anyone see anything weird with my voltages? And could anyone give me some peace of mind as to what to truly expect out of the stock circuit as far as volume with the diodes in play goes?
          As I was writing this post I stuck an lpb-1 on the breadboard after everything which realllllly opened it up and made it sound like what I was expecting it to be. If I have to go that route when I get it in a box then so be it but if someone could help me get the stock circuit to be as loud as that, or as loud as some others have claimed their builds to be, I would be rather smitten. If it is what it is, then I could finally put the doubts in my build to rest and have fun bastardizing this thing from here on out but anyyyyy help putting this case to rest would be really appreciated 

[duck_arse]

Some modding of some values for trim pot biasing helped quell the fart and got it sounding nice but to try and goose more volume (raising the 4.7k to 10k)ultimately lead to nothing.

Here are my voltages for Q1 and Q2 as they stand now:
2n404a
hFE: 38
C: 3.55
B: 3.82
E: 3.87

2n3965
hFE: 284
C: 5.85
B: 3.91
E: 3.73

Everything seems relatively normal but does anyone see anything weird with my voltages?

what trimpot where?

the only 4k7 I can see on that circuit is the led clr. that's not going to affect the volume. well, you'd be really hoping it wouldn't. as for your voltages, and seeing as you asked, you show two different readings for the transistor emitters, yet the circuit shows them hard shorted together. what's going on there?

if you remove the clipping bits, and the volume pot, and take output from the C6, do you have massive gobs of volume? if you then add the volume pot, do you still have massive volume at C6? at the pot wiper? if you have gobs, and then add the dlipping stuff, has all your massives disappeared again?

can you show us your breadboarded thing, in photographic form?

also: what voltage do you read at the top of the volume pot when it's fitted?

[iainpunk]

the diodes simit the signal to 2x .290v = .580v most guitars are about as loud as that, but i have a guitar that puts out near 2.5v on the attack (is capable of passively making LED's clip) and stays over 1v for quite a long time, this guitar would be quite a bit louder than this pedal. if your guitar has high output pickups, a drop in volume is to be expected.

if you want some volume back, try higher Vf diodes, like 1n4001, 1n4148 or Red LED's.

cheers

[Bandwagonesque]

Some modding of some values for trim pot biasing helped quell the fart and got it sounding nice but to try and goose more volume (raising the 4.7k to 10k)ultimately lead to nothing.

Here are my voltages for Q1 and Q2 as they stand now:
2n404a
hFE: 38
C: 3.55
B: 3.82
E: 3.87

2n3965
hFE: 284
C: 5.85
B: 3.91
E: 3.73

Everything seems relatively normal but does anyone see anything weird with my voltages?

what trimpot where?

the only 4k7 I can see on that circuit is the led clr. that's not going to affect the volume. well, you'd be really hoping it wouldn't. as for your voltages, and seeing as you asked, you show two different readings for the transistor emitters, yet the circuit shows them hard shorted together. what's going on there?

if you remove the clipping bits, and the volume pot, and take output from the C6, do you have massive gobs of volume? if you then add the volume pot, do you still have massive volume at C6? at the pot wiper? if you have gobs, and then add the dlipping stuff, has all your massives disappeared again?

can you show us your breadboarded thing, in photographic form?

also: what voltage do you read at the top of the volume pot when it's fitted?

I had stuck 100K trimmers in place of each of the 91K resistors on each of the collectors.

As far as those voltage differences on the emitters, i'm wondering if I measured that while my meter was jumping around. not sure exactly what went wrong but just went ahead and tested again and they both matched up at -4.45V

Ahh sorry about that. I had forgot to mention that on that schematic I posted, that resistor doesn't seem to be there. The 4.7K in series with one of the diodes that I replaced with can be seen though on this schematic. Sorry for that confusion.




I went ahead and removed the ending portions of the circuit right after c9/100nF. This did bring the volume right back up. I had bypassed the diodes earlier keeping the output volume pot there and it did much the same. While it raised the volume, losing those 1n695's kind of neutered the upper octave'ness I was so pleased to have nailed with this breadboard attempt, what had alluded me the first time.

And the volume raise, just instinctively felt weird, like there should be more on tap but I do realize this isn't like removing the diodes in other circuits since these fall immediately before the output. i'm gonna try to breadboard tim e's take on the circuit to see if the diodes in bypass compete with each other volume wise. Gonna sit down now and probe my way through the front side of the circuit up until the diodes and see if I did anything weird. But til I can update here are some shots of the current breadboard if that may help.

Hmmmm. and one real weird thing to note, I can't get anyyyy reading off my volume pot as far as voltages, the last voltage I can grab off a component is where everything meets off Q2's emitter. It's real strange, I double checked my layout on the breadboard and the diodes when pulled increase volume, and the volume pot functions just as it should be no voltage reading at all off any pin off the output pot? Weird.

Thanks a bunch though for the help Iaianpunk and duckarse. I did use a low output strat as well and while the fuzz most definitely reacted differently to the load, it didn't do much to help in volume. Gonna try to see if I can get some volume with different diodes while retaining that really nice octave-y effect.

[iainpunk]

there should be 0v DC on all pins of the volume pot, as the output capacitor blocks DC and the resistance of the pot drains any stray charge to ground, so 0v is good.

i haven't build the HP with the *correct* components and values, but using Ge diodes does leave the output volume a bit lacking, and if i were to build another one today, (if not my ''instant coffee'' version), i would probably add an extra gain stage on the end.

cheers

[duck_arse]

As far as those voltage differences on the emitters, i'm wondering if I measured that while my meter was jumping around. not sure exactly what went wrong but just went ahead and tested again and they both matched up at -4.45V

not really minus, is it?

I can't get anyyyy reading off my volume pot as far as voltages, the last voltage I can grab off a component is where everything meets off Q2's emitter.

ahh, yes, sorry - I sometimes do that, just to see what results we get back. no, of course there is no DC voltages other than zero to be read from the pot. if you did read a voltage there, we'd have something to hang our hats on. and of course you mean the collector where it all joins up, don't you.

I'd rearrange that tant and greencap where their legs cross, just in case.

the perco I built had only 3V8 on the npn collector, and 1V5 on the emitters. a long way from your voltages - needless to say I had a few different resistor values as well.

[pinkjimiphoton]

try a hotter si. i use bc337 usually in this circuit, works pretty good. sometimes go with bc549 too. percs aren't real loud. if ya want it to be louder, ya gotta go with a hotter silicon, or change the diodes out.
personally, i find that the combo of a pink led and an 1n34/60 subbed for the stock diodes seems to work fairly well. raises the volume slightly from the "stock" but still sounds pretty close to the original circuit.

that said, i find it sounds best being driven by another circuit

i like tim escobedo's jerkulator better.

[Bandwagonesque]

As far as those voltage differences on the emitters, i'm wondering if I measured that while my meter was jumping around. not sure exactly what went wrong but just went ahead and tested again and they both matched up at -4.45V

not really minus, is it?

whoops, most definitely 4.45


thanks again you guys, gonna give the jerkulator and pinks suggestions a shot this weekend and hope to report back with some louder results.