Radial Dragster

[Khas Evets]

Any idea what's going on inside one of these? It sounds like a pot to ground, but that would be insulting.

http://www.tonebone.com/tbone-dragster.htm

[Paul Perry (Frostwave)]

I think you are right about it just being a pot to ground. If so:

Cost of components: very little.
Merchandising: considerably more.
Look on face of customer who opens it: PRICELESS!

But, in fairness (and I wish I had a product like this to manufacture!)
unlike all those BS mojo products, this one can actually do what someone wants..
restore the tone to what it was before the high -impedance wireless unit
went in there.

[Khas Evets]

Sure, but couldn't you achieve the same result rolling back the guitar's volume?

[Paul Perry (Frostwave)]

Sure, but couldn't you achieve the same result rolling back the guitar's volume?

Not exactly. Putting extra load across the pickup (yeah, the pickup will see more of the load at max volume) will flatten out the natural resonance shape of the pickup response (forned by the inductance of the coil and any internal or external capacitances). But I'm not a guitar electronics guru so I will leave the field to others

[stm]

Sure, but couldn't you achieve the same result rolling back the guitar's volume?

Not exactly. Putting extra load across the pickup (yeah, the pickup will see more of the load at max volume) will flatten out the natural resonance shape of the pickup response (forned by the inductance of the coil and any internal or external capacitances). But I'm not a guitar electronics guru so I will leave the field to others

I am not getting the picture...

Usually Valve amps have an input impedance of 1 Meg. Traditionally it is desired for effects to have high input impedance, typically in the order of 470k to 1 Meg as well. IIRC, marketing on one of the Boss Phasers (PH-1 or PH-2) said it had an ultra high input impedance of 1 Meg to keep the natural tone of your guitar (or something wonderful like that).  Boss Fet Amp FA-1 has an input impedance of 3.3 Megs.  Moreover, the Hard On and Super Hard On are boosters with EXTRA high input impedance of 5 Meg which supposedly is even greater for extra brightness in tone.  All of the above inclines the balance towards very high input impedances.

Now why are they talking about the need of lowering the impedance. I don't think a wireless unit would have an input impedance greater than 1 Meg anyways, not to say it could be perfectly in the 470k range as well.

And yes, I can see the point in having VERY low input impedances in some "hand selected" effects like the Rangemaster and the venerable Fuzz Face, where this fact is part of the overall tone by acting as additional high frequency filtering for the input.

Confused,

STM

[zachary vex]

Sure, but couldn't you achieve the same result rolling back the guitar's volume?

Not exactly. Putting extra load across the pickup (yeah, the pickup will see more of the load at max volume) will flatten out the natural resonance shape of the pickup response (forned by the inductance of the coil and any internal or external capacitances). But I'm not a guitar electronics guru so I will leave the field to others

i'm not sure if i can see an advantage to loading down the pickup to simulate being connected directly to an amplifier.  to my understanding, a guitar's output impedance is determined by the load of the volume pot and tone control, self-resonance of the pickup, and the exact position of the output volume control... all combined with the input impedance of the amplfier and series/parallel impedance of the cable in-between to create the guitar/amp relationship.  

when combined with a transmitter, how would loading the guitar directly with a pot to ground help simulate the guitar being connected to the amp?  let's do a little thought experiment.

when the guitar's volume and tone pots are at maximum, the guitar's output impedance is highly reactive and basically determined by the impedance of the pickups selected, often (resistive-wise) in the 7k to 15k range.  the tone sensitivity to loading at this point is at it's most critical point.  the amp's input impedance (when combined with the cable) is roughly 1M in parallel with some tens or hundreds of pF to ground.  as the user turns down the guitar's output volume, the output jack on the guitar's resistance to ground drops while the series resistance from the output jack to the pickup RISES.  remember, as the wiper moves down, a resistance appears in series with the pickup between the wiper and the hot pin on the volume pot.  this resistance is easily much higher than the pickup's resistance!  halfway down (resistively) on a 250k pot, the series resistance to the pickup is 125k (ten times the pickup's resistance) and the load to ground at the output jack is now also 125k ohms.  the output impedance has gone up by 10 times!  this explains why we often see guitar hum RISE as we turn down the volume control, until it gets quite low, especially on inexpensive guitars with poor shielding.  

ideally, a device that would simulate the activity of the guitar's pickup/controls in relation to the amp and transmit this beyond a wireless system would monitor the position of the volume control (and tone control, even more complex!) on the guitar and manipulate the series/parallel-to-ground resistances at the OUTPUT OF THE RECEIVER.  to my understanding, changing something at the input of the transmitter isn't going to help... the real control over impedance needs to be at the output of the receiver where the interaction with the amp (or fuzz boxes, even more trouble!) takes place.

i've spent a lot of time thinking about this very thing.  i have some ideas for a solution to the problem... i don't know that they'd help solve the problems of the wireless user, but i think they're more scientifically grounded than loading a pickup, if that's what the dragster does.

8^)  happy holidays!

[zachary vex]

Sure, but couldn't you achieve the same result rolling back the guitar's volume?

Not exactly. Putting extra load across the pickup (yeah, the pickup will see more of the load at max volume) will flatten out the natural resonance shape of the pickup response (forned by the inductance of the coil and any internal or external capacitances). But I'm not a guitar electronics guru so I will leave the field to others

I am not getting the picture...

Usually Valve amps have an input impedance of 1 Meg. Traditionally it is desired for effects to have high input impedance, typically in the order of 470k to 1 Meg as well. IIRC, marketing on one of the Boss Phasers (PH-1 or PH-2) said it had an ultra high input impedance of 1 Meg to keep the natural tone of your guitar (or something wonderful like that).  Boss Fet Amp FA-1 has an input impedance of 3.3 Megs.  Moreover, the Hard On and Super Hard On are boosters with EXTRA high input impedance of 5 Meg which supposedly is even greater for extra brightness in tone.  All of the above inclines the balance towards very high input impedances.

Now why are they talking about the need of lowering the impedance. I don't think a wireless unit would have an input impedance greater than 1 Meg anyways, not to say it could be perfectly in the 470k range as well.

And yes, I can see the point in having VERY low input impedances in some "hand selected" effects like the Rangemaster and the venerable Fuzz Face, where this fact is part of the overall tone by acting as additional high frequency filtering for the input.

Confused,

STM

we were typing our responses at the same time... guitar-oriented electronics is a gas, huh?  8^)

[Steben]

In a few words: I'm quite disgusted as a matter of fact.

[zachary vex]

In a few words: I'm quite disgusted as a matter of fact.

i don't get it.  you're disgusted because someone decided to market one approach to solving a real problem, whether or not it is viable? 

[Steben]

You only need to mod your onboard pot or the following electronics to achieve the same. Or simply put an EQ in your effect chain.
Is there anyone who thinks the "great names" would find this useful? Their effect chain is so vastly complex you won't hear a thing of difference with this (I mean how many EQ's does Gilmour uses?). This has such a narrow-band specific touch...

Yes, it's personal. Maybe hysteric. But hysteric doesn't mean "wrong". I don't like blown-up "solutions" which in fact are answers to artifcial problems. Some may buy it. I definitely not.

BTW: variac players must be rolling and tumbling on the floor right now.

[zachary vex]

*shrug*

series impedance from the output of the wireless receiver is completely out of place in simulating the guitar/amp relationship... it has no relevance with respect to the output of the REAL guitar.  that's the problem... but the solution is most certainly not loading the pickup.

[stm]

For those interested in a circuit for LOADING and UNLOADNG the guitar please check this:

http://www.diystompboxes.com/smfforum/index.php?topic=39559.0

[Steben]

*shrug*

series impedance from the output of the wireless receiver is completely out of place in simulating the guitar/amp relationship... it has no relevance with respect to the output of the REAL guitar.  that's the problem... but the solution is most certainly not loading the pickup.

Well, if it's about simulating amp/guitar relationship you have to make sure to simulate the amp's impedance, which is practicaly always around 1Mohms. This is zero loading in hearable terms.
If you would plug your guitar into a cassete deck you would hear no highs at all and almost no mids, yes, but that's not what we mean with "pleasant warmth" do we?

[gaussmarkov]

For those interested in a circuit for LOADING and UNLOADNG the guitar please check this:

http://www.diystompboxes.com/smfforum/index.php?topic=39559.0

[Paul Perry (Frostwave)]

It's only after I post a reply here, that I find out how much I don't know...... but, that's well worth knowing!! And I think there will be more posts yet

[zachary vex]

...Well, if it's about simulating amp/guitar relationship you have to make sure to simulate the amp's impedance, which is practicaly always around 1Mohms. This is zero loading in hearable terms...

i find that increasing the input impedance of a device from 1M to 5M causes a distinctly audible increase in high treble, the glassy part of the guitar's range.

[Tim Escobedo]

With my setup, i can't really tell any difference once the input impedance of a particular circuit is above about 2M. And I often find input impedance in the range between 100k and 2M often difficult to distinguish unless I can A/B compare them. It seems to get really noticable below 100k, down to about 5k, when i generally think it gets too noticable.

I have used a simple variable resistance-to-ground to offer variable input impedance to op amp fuzz circuits, normally capable of very high input impedance, and it works well to warm things up like loaded passive pickups usually do.

I cant say if the Dragster really does what it claims, or if it's really a resitance-to-ground. Way back when Jack Orman ran his Delphi forum, I floated the idea of using the large value series inductor to make a low impedance signal look like a high impedance pickup signal. It seems like a pretty quick and dirty way to accomplish the job. The purely resistive, or resistive/capacitive methods weren't cutting it. Jack has since written up a page on the concept. It does work to warm up a buffered signal into the likes of a Fuzzface and such. Despite the downsides like size, cost, and potential hum pickup, it's not bad. Perhaps the Dragster is a variable resistance in parallel with a inductor, all in series with the signal path, which would allow variable loading and bypass, all passive.

[Paul Perry (Frostwave)]

I can't help feeling, that the Dragster is being put in the wrong place. Surely the input of a radio transcmitter more closely resembles the input of an amp (both very high) than the OUTPUT of a radio receiver (very low) does the output of a guitar pickup? In which case, you would be better off shoving a series resistance after the reciever, rather than a parallel resistance in front of the transmitter (if that is what it is). That would certainly be the case if you had a fuzz before the amp.

[bwanasonic]

I have no idea what mechanism the Dragster uses, but I am pretty sure Radial actually tested the thing and made sure it performed the desired function. Despite the implication by some that Radial is somehow scamming, they are not known for making products that don't do what they say they do. In fact, they are known for making products that do what they say they do very well.

Kerry M

[big muff cabbage]

posting here to keep everything in one topic.  not sure if it's bad internet etiquette to resurrect a topic.  i purchased this thing a long time ago to see if it would help me.  i've always wondered what was inside, because sometimes it's better to troubleshoot based on schematics.  turns out someone else has finally opened it up and posted pics.

http://i3.photobucket.com/albums/y99/drmccormick/DSC00593.jpg
http://i3.photobucket.com/albums/y99/drmccormick/DSC00594.jpg
http://i3.photobucket.com/albums/y99/drmccormick/DSC00595.jpg
http://i3.photobucket.com/albums/y99/drmccormick/DSC00597.jpg

it probably works well if you need something like that.  i hope this helps somebody.