Rotosound Fuzz - too quiet

thickarms · Post by **thickarms** » Wed Jun 26, 2013 10:28 am

Long time no board etc. etc.

In my time off I came into some money so decided to treat myself to a new fuzz. I ended up choosing the Rotosound Fuzz after A/B'ing it against loads of others in the shop. AMAZING sounding pedal really buzzy, 60s garage tones with the treble cranked and almost Sovtek Big Muff tones with it rolled off.

Had my first proper practice with it last night and was struggling a bit. With the volume and fuzz on full it was still considerably quieter than my clean tone, I thought it might be a battery problem so swapped out the battery but that made no difference. It was still the same when I took it out of my chain and tried it on it's own. I'm a bit of a novice with fuzz pedals, so wondered if there was anything I was doing wrong.

My current set up is:
Fuzz -> Vox V847 wah -> Boss Space Echo -> Fredric Tremolo -> MXR P90 -> Carlsbro 50 Top

It's also been suggested that I might be able to adjust the volume inside the pedal too. Any ideas??

Pics below:

Noisy Cat · Post by **Noisy Cat** » Wed Jun 26, 2013 10:35 am

You're in Hookworms?

I OWN YOUR CD!

johnnyseven · Post by **johnnyseven** » Wed Jun 26, 2013 10:42 am

At first I thought it could be an issue with headroom on your amp. Is your 50 Top and vintage or modern re-issue? I seem to remember the vintage 50 Top I had had a decent amount of headroom.

thickarms · Post by **thickarms** » Wed Jun 26, 2013 10:52 am

Noisy Cat wrote:You're in Hookworms?

I OWN YOUR CD!

haha! thank you! I've been posting on here, albeit sporadically since Hookworms started!

johnnyseven wrote:At first I thought it could be an issue with headroom on your amp. Is your 50 Top and vintage or modern re-issue? I seem to remember the vintage 50 Top I had had a decent amount of headroom.

It's a 70s one yeah. I don't think it's a problem with the headroom because we swapped the Rotosound out for a different fuzz and then a microamp and they both worked fine. We also tried it with a Fender Twin and it was quiet on there too.

wwrrss · Post by **wwrrss** » Wed Jun 26, 2013 11:01 am

OLD FUZZES AREN'T VERY LOUD.

thickarms · Post by **thickarms** » Wed Jun 26, 2013 11:07 am

stop ruining my dreams sean

dub · Post by **dub** » Wed Jun 26, 2013 11:13 am

You could run a boost at the end of your chain and never turn it off.

Gabriel · Post by **Gabriel** » Wed Jun 26, 2013 11:26 am

Or pop it in a bypass loop with a boost pedal after it. I think Timhulio can add a little boost circuit to fuzz pedals to make them loud too (I'm sure Mike would be able to as well).

thickarms · Post by **thickarms** » Wed Jun 26, 2013 11:59 am

Gabriel wrote:I think Timhulio can add a little boost circuit to fuzz pedals to make them loud too (I'm sure Mike would be able to as well).

NOW WE ARE TALKING!

wwrrss · Post by **wwrrss** » Wed Jun 26, 2013 12:27 pm

thickarms wrote:stop ruining my dreams sean

SORRY! <3 u

tenderstems · Post by **tenderstems** » Wed Jun 26, 2013 4:34 pm

What I would do is make a mark on the internal trim pot for where the gain is set now, and then turn it up to see if that helps, if it doesn't, turn it back.

Without a schematic, I can't offer much more. Sometimes there is a resistor near the volume pot that can roll off the volume prior to the actual volume control. Changing this value will allow you to be above unity volume. Again, would need to see the schematic to confirm.

stewart · Post by **stewart** » Wed Jun 26, 2013 4:38 pm

what does the bias trimpot do? i'd tinker with the gain one first and see if it makes a difference.

Bacchus · Post by **Bacchus** » Wed Jun 26, 2013 4:49 pm

Before dicking around with trim pots, I would try rolling back the gain a little. I've never played this Rotosound pedal, but nor have I ever found a distortion or fuzz that doesn't get completely lost in the mix and compressed when the gain is dimed.

tenderstems · Post by **tenderstems** » Wed Jun 26, 2013 5:17 pm

stewart wrote:what does the bias trimpot do? i'd tinker with the gain one first and see if it makes a difference.

The bias trim pot likely sets the voltage reference for one of the transistors. Fuzzes are often set to half the voltage supply. So for a 9 volt pedal, it would be 4.5 volts. However, some people like to adjust this by ear too, and find sweet spots outside of the standard range. It is also possible to use the bias function to compensate for temperature changes, although I can't tell if these transistors are germanium or silicon. If there are silicon they wont be affected as much by temperature change.

I would leave the bias alone if it sounds fine, but is quiet. If the bias is off, you get notes that choke off, weird sound artifacts and notes that only make fuzz sounds if you hit the strings really hard.

NickS · Post by **NickS** » Thu Jun 27, 2013 8:07 am

Interesting to compare that with this:

► Show Spoiler

Note the additional (2.2Mohm) resistor over by the input and the different treatment of the reissue AC127 germanium transistors.

If you wouldn't mind taking the knobs off, unbolting the pots and giving us a shot of the underside of the PCB.....?

timhulio · Post by **timhulio** » Thu Jun 27, 2013 9:16 pm

Ha. They socket the transistors, get it sounding good, then spoooooge the circuit board.

timhulio · Post by **timhulio** » Mon Jul 08, 2013 1:41 pm

Seeing as the pedal is positive ground and wanting to retain the vital vintage m@j@ I used another AC128 (this pedal has three already) and built the initial boost stage from the Tonebender MkII on some pad board (no time to order some PCBs, needed for gig at the end of the month). Only with a smaller input cap as 4u7 was sounding a bit flubby. The extra boost comes after the volume pot but before the switch. Boosts good, sounds good.

thickarms · Post by **thickarms** » Mon Jul 08, 2013 2:00 pm

so excited!!!

ghost_effects · Post by **ghost_effects** » Tue Jul 09, 2013 7:48 am

just saw this, i know the work has been done but I do believe most vintage MKIII circuits had a volume limiting resistor at the output which a lot of people bypass with a wire for more output, just out of interest Tim do you know if this was the case with this circuit?

timhulio · Post by **timhulio** » Tue Jul 09, 2013 8:23 am

Yep, the 220k resistor between the tone and volume pots. In this version it's 100k (R10 on the board), but bridging it didn't result in masses more volume.

On a side note, I noticed the other week that Christian at Magnetic Effects has built some of these Tonebenders using a charge pump to get the positive ground supply, while allowing use of a standard 9V DC center negative adapter. That sounds like a pretty clever idea.