impedance match for woolly mammoth

[tm486]

Hey,

I have been reading about people's experiences with the woolly mammoth and active basses. Many people advise that it is only worth using with a passive bass. As far as i understand, it isnt a matter of just turning the volume on the guitar down, its an impedance issue.

What i want to know is, could i use one of the devices below along with a 1/4" Mono to male XLR cable to play my active basses through the mammoth and achieve similar results to passive basses?


[url="http://whirlwindusa.com/catalog/black-boxe...ices/little-imp"]http://whirlwindusa.com/catalog/black-boxe...ices/little-imp[/url]

[url="http://www.shure.co.uk/products/accessories/a85f"]http://www.shure.co.uk/products/accessories/a85f[/url]


I am new to effects and impedance and all this lot so simple explanations of why this would or wouldn't work would be much appreciated.


Another possibility, the effects send and return on my amplifier (Ashdown MAG 300), are stated as being 22k ohms on the Ashdown website, would this be a considered a high or low impedance and therefore could i place an effect such as the woolly mammoth within the effects loop, getting results similar to a passive bass.

[url="http://www.ashdownmusic.com/bass/detail.as...=mag&ID=112"]http://www.ashdownmusic.com/bass/detail.as...=mag&ID=112[/url]

Any replies will be much appreciated

Thanks

Tom

Edited March 29, 2011 by tm486

[martindupras]

Hi Tom.

Most fuzzes want to see a high impedance signal from the pickups.

I believe what you want is an impedance buffer: in essence a unity-gain pedal that takes your low-impedance input and turns it into a high impedance signal. I can't remember off-hand who makes some but several small independent pedal makers make such things (I guess there just isn't enough demand for a big company to market such a product.)

Here's a thread discussing one: [url="http://basschat.co.uk/index.php?showtopic=22126&pid=224852&st=0&#entry224852"]http://basschat.co.uk/index.php?showtopic=...mp;#entry224852[/url]

- martin


[quote name='tm486' post='1181031' date='Mar 29 2011, 05:12 PM']Hey,

I have been reading about people's experiences with the woolly mammoth and active basses. Many people advise that it is only worth using with a passive bass. As far as i understand, it isnt a matter of just turning the volume on the guitar down, its an impedance issue.

What i want to know is, could i use something like the 'Whirlwind little IMP' along with a 1/4" Mono to male XLR converter to play my active basses through the mammoth and achieve similar results to passive basses?


[url="http://www.guitarcenter.com/Whirlwind-Little-IMP-Lo-to-Hi-Impedance-Matcher-427600-i1134878.gc"]http://www.guitarcenter.com/Whirlwind-Litt...600-i1134878.gc[/url]

[url="http://www.maplin.co.uk/1-4-mono-socket-to-xlr-plug-43159"]http://www.maplin.co.uk/1-4-mono-socket-to-xlr-plug-43159[/url]


I am new to effects and impedance and all this lot so simple explanations of why this would or wouldn't work would be much appreciated.


Another possibility, the effects send and return on my amplifier (Ashdown MAG 300), are stated as being 22k ohms on the Ashdown website, would this be a considered a high or low impedance and therefore could i place an effect such as the woolly mammoth within the effects loop, getting results similar to a passive bass.

[url="http://www.ashdownmusic.com/bass/detail.asp?section=mag&ID=112"]http://www.ashdownmusic.com/bass/detail.as...=mag&ID=112[/url]

Any replies will be much appreciated

Thanks

Tom[/quote]

[tm486]

[quote name='martindupras' post='1181725' date='Mar 30 2011, 12:10 AM']Most fuzzes want to see a high impedance signal from the pickups.

I believe what you want is an impedance buffer: in essence a unity-gain pedal that takes your low-impedance input and turns it into a high impedance signal.[/quote]

Hey,

I had seen this thread but i have had no luck in finding anything designed solely for this purpose. This is why i was wondering whether these might do the trick as they do say they go from a low z XLR input to a high z jack.

Is this not likely to be the case? If so, i would appreciate help from anyone who might know who makes/stocks an impedance buffer.

Thanks for your help martin,

Tom

[dannybuoy]

Here's the circuit: [url="http://www.muzique.com/lab/pickups.htm"]http://www.muzique.com/lab/pickups.htm[/url]

Max at SFX does custom work, might be worth asking him?

[martindupras]

I'd say: try it. You can't harm anything. All that's going to happen is that the sound will change, and if it sounds good to you, who cares whether it's textbook correct?

My guess is that the Low-Z to Hi-Z converters you linked to are designed to take a microphone level signal, which is going to have a very low impedance in the region (I think) of 600ohm, and convert that to a much higher impedance which I'm going to guess is going to be in the region 10k. I'm also guessing that active electronics on instruments are not such low impedances as 600ohm, so you're probably going to get an even higher impedance than you would get from an impedance matching box. Unless I'm mistaken (I'm doing this from memory) the net effect is probably that you're going to get more gain going into the fuzz. Probably not a bad thing, if you want fuzz.

Personally, I'd build a tiny little box with just and input and an output, which I would find more pedalboard-friendly solution that a 1/4"-to-XLR lead into an XLR-1/4" impedance adapter.

- martin



[quote name='tm486' post='1181754' date='Mar 30 2011, 12:40 AM']Hey,

I had seen this thread but i have had no luck in finding anything designed solely for this purpose. This is why i was wondering whether these might do the trick as they do say they go from a low z XLR input to a high z jack.

Is this not likely to be the case? If so, i would appreciate help from anyone who might know who makes/stocks an impedance buffer.

Thanks for your help martin,

Tom[/quote]

[tm486]

[quote name='martindupras' post='1181769' date='Mar 30 2011, 01:22 AM']I'd say: try it. You can't harm anything. All that's going to happen is that the sound will change, and if it sounds good to you, who cares whether it's textbook correct? [/quote]

Thanks, i reckon i'll give it a try, from the link that dannybuoy offered, it doesn't look too complicated. Although which circuit would be better? i assume that the second circuit will allow me to tailor the impedance so i can use different active basses to get the same results?

Thanks for the info on the mic level converters, it was exactly what i was looking for. Whilst the extra gain might come in handy for some, the woolly mammoth has more than enough gain for me so i think having a go at building the buffer would be a better idea.


Thanks for the input

Tom

[GarethFlatlands]

[quote name='dannybuoy' post='1181762' date='Mar 30 2011, 12:57 AM']Here's the circuit: [url="http://www.muzique.com/lab/pickups.htm"]http://www.muzique.com/lab/pickups.htm[/url]

Max at SFX does custom work, might be worth asking him?[/quote]

It's a very simple circuit, might be worth giving it a go yourself as long as you can get the pedal enclosures. I've had the parts for a fuzzface sitting round since September!

I guess you could use a plastic enclosure shielded with electrical tape if you plan on leaving it on all the time and don't need a footswitch, it would be easier to work with than metal.

[tm486]

[quote name='GarethFlatlands' post='1182548' date='Mar 30 2011, 06:33 PM']I guess you could use a plastic enclosure shielded with electrical tape if you plan on leaving it on all the time and don't need a footswitch, it would be easier to work with than metal.[/quote]

I have lots of metal working equipment at my disposal so i'm gna go for making a metal enclosure. i am also thinking of adding a 3PDT stompbox type switch so i can get true bypass when im not using the effect or im using a passive bass. This also lets me put an LED in to tell me when its on. I might try putting a SPDT switch so i can use either half the inductor or the whole thing at a flick of a switch, just interested to see what it does to the sound tbh.

Thanks

Tom

[martindupras]

I'd say go for it.

If it was me, however, I'd prototype the circuit first and see if it does and sounds like what you want. It's such a simple circuit that I'd do that on breadboard to save time.

When you do, it's a relatively simple thing to put a switch in. Put it in and see what it sounds like turned on and turned off. In theory, it will only make a difference in tone when the Mammoth is on. The reason why is because when the Mammoth is off, the only effect the impedance change will have will be on the next pedal, and nearly all pedals (except) fuzzes are designed to take a high impedance; the higher the better. That is especially true of buffered pedals. Boss pedals, for instance, have a very high input impedance (most have an input impedance of 1M ohm.)

All of this to say: unless you want to be able to switch between the Mammoth driven by a high impedance and by a low impedance, there will be no advantage to turning it on and off, and therefore you can lose the switch. If you lose the switch, you can also lose the LED. If it's not switched, it doesn't have to be a sturdy box so a very small plastic enclosure would probably do, which would save you some time, effort and money.

I had another thought: pedals usually have a high input impedance and a low(er) output impedance. Boss pedals are typically 1k ohm on output. Some are designed to have a slightly higher impedance so that the next pedal "thinks" it's seeing just a guitar pickup. If you have pedals lying around, you could look at their spec: it could very well be that there is one of your pedals that would be a good match for the WM. I'd say if the output impedance is somewhere in the region of 5k, it'll probably work fine.

- martin


[quote name='tm486' post='1182656' date='Mar 30 2011, 08:01 PM']I have lots of metal working equipment at my disposal so i'm gna go for making a metal enclosure. i am also thinking of adding a 3PDT stompbox type switch so i can get true bypass when im not using the effect or im using a passive bass. This also lets me put an LED in to tell me when its on. I might try putting a SPDT switch so i can use either half the inductor or the whole thing at a flick of a switch, just interested to see what it does to the sound tbh.

Thanks

Tom[/quote]

[tm486]

[quote name='martindupras' post='1182860' date='Mar 30 2011, 11:21 PM']If it was me, however, I'd prototype the circuit first and see if it does and sounds like what you want. It's such a simple circuit that I'd do that on breadboard to save time.

All of this to say: unless you want to be able to switch between the Mammoth driven by a high impedance and by a low impedance, there will be no advantage to turning it on and off, and therefore you can lose the switch. If you lose the switch, you can also lose the LED. If it's not switched, it doesn't have to be a sturdy box so a very small plastic enclosure would probably do, which would save you some time, effort and money.

I had another thought: pedals usually have a high input impedance and a low(er) output impedance. Boss pedals are typically 1k ohm on output. Some are designed to have a slightly higher impedance so that the next pedal "thinks" it's seeing just a guitar pickup. If you have pedals lying around, you could look at their spec: it could very well be that there is one of your pedals that would be a good match for the WM. I'd say if the output impedance is somewhere in the region of 5k, it'll probably work fine.[/quote]

I had that thought, i am going to produce the circuit before i make any enclosure etc so i can test it all. And i hadn't thought about other pedals. but if i want to put the mammoth first in the chain, or i want only the mammoth then i'll need this circuit before it anyway, regardless of my other pedals. But i am definately going to test it and make sure its exactly what i want before i put any effort into making an enclosure or buying other components. If not i'll have to stick with using only my passive through it. Also, i would like a switch as if i wanted to switch basses without having to remove this circuit, i dont know if plugging a passive bass into this would be a problem, but from what i have read, plugging a high impedance passive bass into a low impedance load will not work well?


Thanks

Tom

Edited March 30, 2011 by tm486

[martindupras]

Good point! That's a very good reason to have a switch.

Let me know how you get on.

- martin


[quote name='tm486' post='1182880' date='Mar 30 2011, 11:43 PM']I had that thought, i am going to produce the circuit before i make any enclosure etc so i can test it all. And i hadn't thought about other pedals. but if i want to put the mammoth first in the chain, or i want only the mammoth then i'll need this circuit before it anyway, regardless of my other pedals. But i am definately going to test it and make sure its exactly what i want before i put any effort into making an enclosure or buying other components. If not i'll have to stick with using only my passive through it. Also, i would like a switch as if i wanted to switch basses without having to remove this circuit, i dont know if plugging a passive bass into this would be a problem, but from what i have read, plugging a high impedance passive bass into a low impedance load will not work well?


Thanks

Tom[/quote]

[tm486]

[quote name='martindupras' post='1183055' date='Mar 31 2011, 10:24 AM']Good point! That's a very good reason to have a switch.

Let me know how you get on.

- martin[/quote]


Thanks, it is a little more complicated, but not too bad. I will post on here when its finished hopefully with positive results.

Thanks

Tom

[Quoth'd]

I built my Mammoth & found that the outputs from my Spector & Maverick were so hot that they dirtied the sound (more so than I was wanting).

So I added an input variable resistor to drop the gain on the input to the circuit. Cheap and dirty but enabled me to attenuate the signal so that it didn't overload the pedal, result sounded great too. (since switching back to passive basses, I've removed it though

I used a 100K variable resistor (the small kind so it fitted inside the box with minimal agro and no drilling etc needed) Once fitted it was just a case of testing and adjusting till the input sound was low enough (not too high / not too low) that the pedal worked properly.

input from bass (jack) - - - - (pin1)
|
100K VR - - - - - middle to Mammoth input (pin2)
|
ground - - - - - - - - - (pin3)

Sorry for the crappy drawing

[tm486]

[quote name='Quoth'd' post='1183080' date='Mar 31 2011, 10:41 AM']I added an input variable resistor to drop the gain on the input to the circuit. (since switching back to passive basses, I've removed it though [/quote]


Hi,

I do understand what you mean and that thought had crossed my mind, if it werent for the fact that i have both active and passive basses, i would certainly have tried that. but i want to be able to easily switch back and forth between active and passive basses, so its not the perfect solution for me.

However, i have more active basses than passive, so i will do that if my attempt at this impedance matching pedal fails.

Thanks

Tom

Edited March 31, 2011 by tm486

[martindupras]

You could just put the pot in a box with a switch, before the mammoth. Bypassed, you have the whole signal, with it on it's just attenuated. The pot is working just the same as the volume control on your bass.

- martin



[quote name='tm486' post='1183137' date='Mar 31 2011, 11:22 AM']Hi,

I do understand what you mean and that thought had crossed my mind, if it werent for the fact that i have both active and passive basses, i would certainly have tried that. but i want to be able to easily switch back and forth between active and passive basses, so its not the perfect solution for me.

However, i have more active basses than passive, so i will do that if my attempt at this impedance matching pedal fails.

Thanks

Tom[/quote]

[tm486]

[quote name='martindupras' post='1183198' date='Mar 31 2011, 12:18 PM']You could just put the pot in a box with a switch, before the mammoth. Bypassed, you have the whole signal, with it on it's just attenuated. The pot is working just the same as the volume control on your bass.

- martin[/quote]

I hadnt thought of that, do you know whether it would be a volume or a tone pot or could either be used? because if it was a tone pot, you can get those ones where fully clockwise the pot is disengaged and then i wouldnt even need a switch. I believe they are called no-load pots as when they are fully clockwise they offer no load.

This looks like it could be getting simpler, this is good.

Thanks

Tom

[tm486]

Although i guess it wouldnt matter whether it was a volume or a tone pot, as there are many guides available on how to make a pot 'no-load', so i should be able to do this regardless of whether it is linear or logarithmic.

[Quoth'd]

Volume and tone pots are essentially the same - the only difference is that a tone pot will have a capacitor which soaks up the higher frequencies.

These are reasonable (and cheap): - [url="http://www.maplin.co.uk/standard-potentiometers-2205"]http://www.maplin.co.uk/standard-potentiometers-2205[/url]

The only reason I tend not to use the metal shaft ones is that they're a pain to cut to length.

Maplin also do the metal boxes, jacks & LEDs (although you'll need to run a power circuit if you want an LED to indicate if it's set for active or passive mode).

[tm486]

[quote name='Quoth'd' post='1183376' date='Mar 31 2011, 02:44 PM']Volume and tone pots are essentially the same - the only difference is that a tone pot will have a capacitor which soaks up the higher frequencies.

Maplin also do the metal boxes, jacks & LEDs (although you'll need to run a power circuit if you want an LED to indicate if it's set for active or passive mode).[/quote]

Hey,

So will i wont need a capacitor, i just need to stick the potentiometer between two female jacks and it should work like that? Also, would the 'no-load' pots work as a true bypass when they are set to no load? either way, it seems like a much easier method which i can build and test tomorrow if my local maplins has the parts in stock.

Thanks

Tom

[tm486]

Hey,

I have found a temporary solution. I use a Line6 backtrack to record tracks, and if i stick this before the mammoth it sounds a lot better. I dont think its perfect though as when the pinch knob it past 12 o'clock, it sounds bad once again. I dont have my passive bass with me at the moment but when i go home for easter, i'll be able to tell whether this works or not. I am still going to try the potentiometer as if i want to record anything whilst using the mammoth, i'll need to have another method of matching the impedance, but until then i at least have some way of using it which sounds good.

Thanks for all your input and i'll post on here after i have tried the potentiometer and let you know how it works out.

Tom

[Quoth'd]

[quote name='tm486' post='1183679' date='Mar 31 2011, 06:45 PM']Hey,

I have found a temporary solution. I use a Line6 backtrack to record tracks, and if i stick this before the mammoth it sounds a lot better. I dont think its perfect though as when the pinch knob it past 12 o'clock, it sounds bad once again. I dont have my passive bass with me at the moment but when i go home for easter, i'll be able to tell whether this works or not. I am still going to try the potentiometer as if i want to record anything whilst using the mammoth, i'll need to have another method of matching the impedance, but until then i at least have some way of using it which sounds good.

Thanks for all your input and i'll post on here after i have tried the potentiometer and let you know how it works out.

Tom[/quote]


I think the Pinch knob controls the power to the transistors (from memory, I may be mistaken) - makes it sound more torn the higher you set it - this is the most susceptible to input levels. I always used to hate the way all my pedals sounded totally different with different basses & needed constantly resetting if I wanted to change between them.

Nice one on the Line6 by the way - what's it like? I looked at the reviews but never got round to getting one to play with.

[tm486]

[quote name='Quoth'd' post='1184016' date='Mar 31 2011, 10:13 PM']I think the Pinch knob controls the power to the transistors (from memory, I may be mistaken) - makes it sound more torn the higher you set it - this is the most susceptible to input levels. I always used to hate the way all my pedals sounded totally different with different basses & needed constantly resetting if I wanted to change between them.

Nice one on the Line6 by the way - what's it like? I looked at the reviews but never got round to getting one to play with.[/quote]

Yea, i hope that the use of the potentiometer will let me set the input to a level which allows the gate control to be used.

The Line6 is great, i haven't got the version with the microphone but i just leave it plugged in my signal chain. It is so easy to record stuff and you can put it before or after effects and they work well. The only thing that can be annoying, the level of overdrive which sounds great through a 15" speaker doesnt sound so great when recorded. But if you intended to use it to record and add effects on the computer its fantastic. I personally only use it to record songs which i sync to the video on iMovie at the moment. i have uploaded a couple to youtube and the audio quality is much better than people who record with a webcam microphone or similar.

Thanks

Tom

[martindupras]

Try lowering the volume on your bass to somewhere around 25%-50%. That will behave much like the pot you would put in the box, since it's essentially the same thing. If it sounds great, then you know that the pot-in-a-box solution will work, and you can probably work out what pot will work best.

I'm very tired so correct me if I make a mistake in the following logic.

A volume pot travels from no resistance to the maximum resistance; 500k is common for volume pots. Therefore, assuming the pot is linear, set at the halfway point you'd get 250k of resistance, say. At 1/4, you'd get 125k. It wouldn't be exactly that of course because even a linear pot is not totally linear, but it would be close enough. If, say, it sounds good between the 1/4 and 1/2, then that gives you a ballpark for what pot to use.

- martin


[quote name='tm486' post='1183679' date='Mar 31 2011, 06:45 PM']Hey,

I have found a temporary solution. I use a Line6 backtrack to record tracks, and if i stick this before the mammoth it sounds a lot better. I dont think its perfect though as when the pinch knob it past 12 o'clock, it sounds bad once again. I dont have my passive bass with me at the moment but when i go home for easter, i'll be able to tell whether this works or not. I am still going to try the potentiometer as if i want to record anything whilst using the mammoth, i'll need to have another method of matching the impedance, but until then i at least have some way of using it which sounds good.

Thanks for all your input and i'll post on here after i have tried the potentiometer and let you know how it works out.

Tom[/quote]

[tm486]

[quote name='martindupras' post='1184055' date='Mar 31 2011, 10:54 PM']Try lowering the volume on your bass to somewhere around 25%-50%. That will behave much like the pot you would put in the box, since it's essentially the same thing. If it sounds great, then you know that the pot-in-a-box solution will work, and you can probably work out what pot will work best.

I'm very tired so correct me if I make a mistake in the following logic.

A volume pot travels from no resistance to the maximum resistance; 500k is common for volume pots. Therefore, assuming the pot is linear, set at the halfway point you'd get 250k of resistance, say. At 1/4, you'd get 125k. It wouldn't be exactly that of course because even a linear pot is not totally linear, but it would be close enough. If, say, it sounds good between the 1/4 and 1/2, then that gives you a ballpark for what pot to use.

- martin[/quote]

I have been using my bass set to about 25% as i had the same thought as you and discovered that it did sound better there. Surely though, as impedance is measured in ohms, and i want to raise the impedance, when the volume is at 25%, the resistance would be more like 75% of the 500Kohms of the potentiometer? so i would be looking at a potentiometer of around 350-400k? but then would it be a better idea to go for something larger like another 500k one?

Cheers

Tom

Edited March 31, 2011 by tm486

[martindupras]

I did say I was tired.

You're right. At 1/4 vol you have 3/4 of the resistance. If you have a 500k pot you'll get 0-500k resistance. If you wanted to restrict the range you could put another resistor in series, e.g. 250k resistor + 250k pot would give you a range of 250k-500k. I think.

- martin


[quote name='tm486' post='1184060' date='Mar 31 2011, 10:59 PM']I have been using my bass set to about 25% as i had the same thought as you and discovered that it did sound better there. Surely though, as impedance is measured in ohms, and i want to raise the impedance, when the volume is at 25%, the resistance would be more like 75% of the 500Kohms of the potentiometer? so i would be looking at a potentiometer of around 350-400k? but then would it be a better idea to go for something larger like another 500k one?

Cheers

Tom[/quote]