Crossfire/Belcat/Others TRM-507 Tremolo... Mods?

[ozboomer]

For the sake of completeness(!) and the fact that I really wanted a tremolo effect pedal (and couldn't be bothered with the delay coming from having to build one... that will still probably need tweaking), I lashed-out A$60 (which is still cheaper than any 'complete kit') for a Crossfire TRM-507 Tremolo Pedal this morning, viz:-

It's (sort-of) cheap(-ish) and doesn't have a lot of bells and whistles but I think it's going to be (more-or-less) servicable for my current applications (for example, this current GN2 jam), so I wasn't too fussed... and I always thought I'd be able to hack it about somehow if I needed to...

However...

...upon trying it out, it seems there are some... "issues"... that all the YouTube and eBay videos conveniently avoid. My specific discoveries:-

• The "Rate" control seems to be pretty-well configured; there is a fairly smooth, even change from the minimum rate (~1 Hz) to the maximum rate (~10 Hz estimated). In general, I'm pretty happy with the range and variation in this control.
  
  
• The "Depth" control doesn't seem to do very much from the minimum (8 o'clock) position through the 11 o'clock position (ie over 1/3 of the range does 'nothing'). Through most of that range, there is no significant change in the sound I hear (although a 'scope may show something different). From 11 o'clock through to the maximum (4 o'clock) position, you can certainly hear a change in the intensity of the pulsing effect.
  
  
• The "Wave" control seems to have a similar restricted usable range. At the minimum (8 o'clock) position, it sounds like it's running a triangle or sine wave shape.. and as the dial moves through the 9 o'clock position, it starts to sharpen some... and at 11 o'clock, it starts to sound "choppy", maybe a square or ramp wave shape. From that position through to the maximum (4 o'clock) position, I can't hear any significant change in the way the tremolo works; it's "choppy" and that's all (ie nearly 2/3 of the range does 'nothing').
  
  
• The LED is only an "effect ON/OFF" indicator and it doesn't follow the pulses of the tremolo. No big deal for me but is certainly something to be aware of.
  

Now, I can't find any schematic for the pedal but I have seen the insides of it (as well as a few other Crossfire pedals) and the design uses SMDs (Surface Mount Devices). In general, this means I have very little chance of modifying anything on the circuit board... However, perhaps I could put a capacitor or something on the control pots, to try and change the behaviour of the "Depth" and "Wave" controls.

Would you think there's any point in doing this, given that I have no schematic? If I can suss out the values of whatever the pots connect to/through, there might be a point to trying something? ...or would I be best to leave the silly thing alone and just accept "this is the way THIS UNIT works" and save-up until I can get a "real" pedal (I've been keen on the Empress Tremolo... but not at A$360(!) ...or even US$249)... It's just that the tremolo effect in my V-Amp 2 does nothing for me at all, really..

Thanks for your thoughts, folks.

[JohnH]

Hi Oz, much as I like tweaking, Id probably leave it alone. Was it this unit on your recent reverb samples in the Cowabunga thread? they sounded quite nice.

The circuit of this unit is likely based on some ancient Boss unit, available on the web, so it may be at least an interesting excecise to find such and understand it. It may lead to a notion that a resistor across certain pots might change their sweep for the better. (just a thought, I dont know)

John

[ozboomer]

Feb 26, 2011 16:04:10 GMT -5 JohnH said:

Hi Oz, much as I like tweaking, Id probably leave it alone.

Well, with that comment from one of our "recognized gurus" (or should that be "groovy guru"(!)), I WILL probably leave it be (for now)...

Was it this unit on your recent reverb samples in the Cowabunga thread? they sounded quite nice.

Yup, yup.. As I say, it's really that FRV-1 that makes a difference to the whole sound ( and perhaps the Dream 90 pup has something to do with it, too! ) I've never even (knowingly) been in the same room as a 'real' Fender reverb tank, so I don't really have the ear/experience of most other surf aficionados here... but when I plugged in the pedal and cranked the controls up.. and I heard *me* making sumgai's *fwip* noises, I just sed "That'll do (pig)"

The circuit of this unit is likely based on some ancient Boss unit, available on the web, so it may be at least an interesting excecise to find such and understand it.

Been there, done that (more or less). The Boss TR-2 Tremolo circuit is easy enough to find and I've already been fiddling with it (akin to my ongoing mods/studies for my booster becoming a pseudo- Boss FA-1 JFET pre-amp)..

It may lead to a notion that a resistor across certain pots might change their sweep for the better. (just a thought, I dont know)

Ahhh! Another Eureka moment for GN2. Excellent thought.. I'll proceed to go and check that out.. Fanx!!

[ny3]

If you look at the schematic of the Boss unit and take out the board of the Crossfire unit you'll see why there is likely to be a problem with the Wave and Depth controls. But it can be fixed.

The Crossfire and Boss are remarkably similar but the the Depth and Wave pots look like they've been swapped (accidentally?) in the Crossfire circuit. These two pots are the same resistance but have different tapers: one is log, one is linear. If the tapers are wrong the control won't vary smoothly.

I guessed this was the cause of the problem you described above so I desoldered the Depth and Wave pots and swapped them over.

Problem solved.

Feb 26, 2011 7:13:46 GMT -5 ozboomer said:

 

• The "Depth" control doesn't seem to do very much from the minimum (8 o'clock) position through the 11 o'clock position (ie over 1/3 of the range does 'nothing'). Through most of that range, there is no significant change in the sound I hear (although a 'scope may show something different). From 11 o'clock through to the maximum (4 o'clock) position, you can certainly hear a change in the intensity of the pulsing effect.
  
  
• The "Wave" control seems to have a similar restricted usable range. At the minimum (8 o'clock) position, it sounds like it's running a triangle or sine wave shape.. and as the dial moves through the 9 o'clock position, it starts to sharpen some... and at 11 o'clock, it starts to sound "choppy", maybe a square or ramp wave shape. From that position through to the maximum (4 o'clock) position, I can't hear any significant change in the way the tremolo works; it's "choppy" and that's all (ie nearly 2/3 of the range does 'nothing').

[newey]

ny3-

Hello and Welcome to G-Nutz2!

You've resurrected an older thread, which is fine, but we haven't heard from ozboomer in a while, so he may miss out on your fix of the problem. But thanks for posting it, for the future reference of others with this unit.

I've recently culled my pedalboard down to 3 pedals, all Boss- an FRV-1, a Tr-2 and a SD-1. I like the Boss trem pedal a lot, does everything I ask of it.

[ozboomer]

Oct 27, 2013 19:48:51 GMT -5 newey said:

...we haven't heard from ozboomer in a while

I'm still about... just rigged for silent running

I've recently culled my pedalboard down to 3 pedals, all Boss- an FRV-1, a Tr-2 and a SD-1. I like the Boss trem pedal a lot, does everything I ask of it.

That's what I ended-up doing (grabbing a TR-2)... and my pedal board, like newey's, now runs:-

Guitar => Boss PSM-5 Master Switch+PSU => Boss TR-2 Tremolo => Boss FRV-1 Reverb => Boss RC-2 Loop Station => Joyo JF-11 Graphic EQ pedal => Home-made (JohnH-style JFET) booster => (amp) or (audio interface input)

I went with the JF-11 EQ as it's quieter out of the box than the Boss GE-7 (and I didn't want to do the op amp change mods, etc which 'fixes' the GE-7).

Trivia: I'm still using the same 9V battery in the booster as I was using in October 2010.. and the signal is still clean and strong. 'mazin'