Passive boosters

this is as complex as I like my wiring :)

t-20-under-jpg.9341
 
  • Like
Reactions: RVA
RVA said:
Don, is the pot necessary? Might it be better to just wire this with a on-off-on mini toggle with cut/off/boost similar to how it is on the push/pull above, but without the pot? It is sold that way above and mimics the Tom Anderson application of this device (assuming they are the same). Thanks.
Click to expand...

The idea of the pot is that in one direction it works more or less like a normal tone control, but in the other it does the boost thing. Hence the centre detent point. But you can always just put a switch in series instead.
 
  • Like
Reactions: RVA
No such thing as genuine boost without a power source.
Passive boost is an oxymoron. You can't add something for nothing.

No such thing as a free lunch.
 
Tony M. said:
No such thing as genuine boost without a power source.
Passive boost is an oxymoron. You can't add something for nothing.

No such thing as a free lunch.
Click to expand...
Agreed, and the quote above explains the technical details of what it does not and does do, reprinted here. However, I have it on my Tom Anderson and love it.
Anyway, it is a cool experiment. I will try it on my incoming ESP LTD. If I like it, I mat add it to some strat-type guitars next


There should be a Torres website in the UK. They sell those pre-wired. There are several things to consider before using one. First, there is no "flat" response position on the pot. Torres claims that "5 is flat", but the device has no zero load position. Second, the "boost" doesn't boost. It is merely another treble roll-off with a resistor to retain a bit more low-to-mid signal, while the small-value cap rolls off only the very highest frequencies. I bought one years ago, because I'd read about it, and wanted to see how to achieve a "boost without batteries". Well, you can't do it, and neither can Torres.
 
Last edited:
DonP said:
The idea of the pot is that in one direction it works more or less like a normal tone control, but in the other it does the boost thing. Hence the centre detent point. But you can always just put a switch in series instead.
Click to expand...
Got it. So the push/pull pot takes this a step farther and gives you a full sweep for each. Thanks
 
Sir Don or someone who knows electronics, can you please explain the connections on these inductors to me? I was expecting only 2 total, but there are 3 per side. How do I make the connections based on the above schematics?

Thanks

20171109_230223.jpg
 
Best way is to use a meter, but I'm guessing these are transformers, not chokes. That being the case, there is one winding each side, each with a centre tap, a bit like a coil split in a pickup. You can verifu that with a test meter by measuring ohms. There should be no connection between the two sides, between any of the pins.

Now pick a side and stick with it. Measure end to end, and middle to each end. I'm expecting the end-to end measurement to be double that of middle to end.

Now you can ignore all the pins except the two end pins on one side - use those and leave the rest unconnected.

upload_2017-11-10_7-42-59.png


The red dots are your connections. The the ohms don't come out as expected, get back to me.
 
DonP said:
Best way is to use a meter, but I'm guessing these are transformers, not chokes. That being the case, there is one winding each side, each with a centre tap, a bit like a coil split in a pickup. You can verifu that with a test meter by measuring ohms. There should be no connection between the two sides, between any of the pins.

Now pick a side and stick with it. Measure end to end, and middle to each end. I'm expecting the end-to end measurement to be double that of middle to end.

Now you can ignore all the pins except the two end pins on one side - use those and leave the rest unconnected.

View attachment 9448


The red dots are your connections. The the ohms don't come out as expected, get back to me.
Click to expand...
Thank you! I will test it this evening.
 
DonP said:
Best way is to use a meter, but I'm guessing these are transformers, not chokes. That being the case, there is one winding each side, each with a centre tap, a bit like a coil split in a pickup. You can verifu that with a test meter by measuring ohms. There should be no connection between the two sides, between any of the pins.

Now pick a side and stick with it. Measure end to end, and middle to each end. I'm expecting the end-to end measurement to be double that of middle to end.

Now you can ignore all the pins except the two end pins on one side - use those and leave the rest unconnected.

View attachment 9448


The red dots are your connections. The the ohms don't come out as expected, get back to me.
Click to expand...
Ok, I do not know why I thought I could wait! So your hypothesis was right on with an addition. One side reads substantially lower from endpins than the other. The readings consistently across the 3 units I have are approx 143 ohms on one side and 58 ohmns on the other. So which side should I use?
 
OK, that is a transformer - probably from a microphone.

Which to use? Start with the high side. If everything seems to be happening at too low a frequency, swap to the low side.
 
  • Like
Reactions: RVA
  • Like
Reactions: RVA
RVA said:
Thank you once again. It seems the buyer or seller did not know what this was.
Click to expand...

I'm not surprised. Even that little blue device on the Rothstein setup you posted earlier actually looks to be a transformer, even though he calls it an "inductor." The Rothstein mod appears to use just one side of the transformer, as Don is describing for you. This approach is also depicted in the schematic in post #12.

So, effectively, from the standpoint of the circuit, itself, it is an inductor. But the physical device is a transformer. The mod only uses one side.

That could be confusing if someone was just trying to procure all the parts on his/her own and was unaware of the difference.
 
  • Like
Reactions: RVA
smitty_p said:
I'm not surprised. Even that little blue device on the Rothstein setup you posted earlier actually looks to be a transformer, even though he calls it an "inductor." The Rothstein mod appears to use just one side of the transformer, as Don is describing for you. This approach is also depicted in the schematic in post #12.

So, effectively, from the standpoint of the circuit, itself, it is an inductor. But the physical device is a transformer. The mod only uses one side.

That could be confusing if someone was just trying to procure all the parts on his/her own and was unaware of the difference.
Click to expand...
Very helpful, thank you. I should really begin to read the instructions!! And now I know which side to use. I assume the primary side reads higher, but I will check and report back.
 
The Villex device seems to be a little different, though. I've been researching this. Whereas I haven't found anything 100% definitive (Villex is very close-hold about what is in his little box!), opinions on other audio forums (not just guitar forums) suggest he is using a step-up transformer. There may be other discreet components in there, as well.

Villex insists it is not merely a filter. I am actually interested in the all-in-one Strat jack replacement he has. It's a completely reversible mod.
 
Last edited:
smitty_p said:
The Villex device seems to be a little different, though. I've been researching this. Whereas I haven't found anything 100% definitive (Villex is very close-hold about what is in his little box!), opinions on other audio forums (not just guitar forums) suggest he is using a step-up transformer. There may be other discreet components in there, as well.

Villex insists it is not merely a filter. I am actually interested in the all-in-one Strat jack replacement he has. It's a completely reversible mod.
Click to expand...
Very cool. If this project does not pan out, I may spring for a Villex myself. I will be sure to postsound samples.

Sorry I do not know this already, but are you an eletrician or electrical enginer?
 
RVA said:
Very cool. If this project does not pan out, I may spring for a Villex myself. I will be sure to postsound samples.

Sorry I do not know this already, but are you an eletrician or electrical enginer?
Click to expand...

No. I'm not an electrician or electrical engineer. I do, however, have formal training in electronics. I did work in that field for a number of years, so I do "get" it.

I do not have anything close to the level of education and experience that Don possesses, however.

These days, I'm more of a sales engineer working in the AV industry. From a technical point of view, it's a step down, since it's not hard-core electronics, like I worked years ago. From a day-to-day point of view, it's a step up. I work directly for the CEO, I meet with customers, and I get invited to see new product in the AV world, so it can be fun. I spend a lot of time writing proposals, too. My computer keyboard never rests!
 
Last edited:
  • Like
Reactions: RVA
You must log in or register to reply here.
Back
Top