HAO - Rust Booster I + Rust Booster II LTD

patafix · Post by **patafix** » 06 Dec 2008, 10:48

Maybe a mod would be to use the first opamp as a voltage follower (or buffer) to increase the input impedance to a much higher value than the original 47K.

JHS · Post by **JHS** » 06 Dec 2008, 13:41

47k is good. The I-impedance is similar to that of the classic trannie boosters. The RB has enough highs so IMHO there's no need to raise the I-impedance.

JHS

Bernardduur · Post by **Bernardduur** » 19 Dec 2008, 12:41

Hmmmmm, this is a very nice booster pedal; love it on bass!

On the lowest booster setting the unit sounds muddy w/ more bass and no more volume then unity but when the booster knob is crancked the fullness of the sound returns and you'll get a nice boost up to crunchy OD that sounds absolute wonderful with my Dumble!

Great build!

Bernardduur · Post by **Bernardduur** » 19 Dec 2008, 13:15

Hmmm, but when I use it on guitar I hear a bass boost making my sound muddy and unatractive. In the bypass mode my amp sound springy and clear, with the unit I get an increase in bass making the sound compressed and dull.

Is this normal? I used a TI TL072

Edit; added a simple BOSS pedal in front of her and now the full spectrum is back!

Fuzzer · Post by **Fuzzer** » 19 Dec 2008, 16:07

I wanna reiterate, If somebody is building this the same as the schematic, keep in mind that the electrolytic capacitor used in the LED swithcing is backwards.

Bernardduur · Post by **Bernardduur** » 20 Dec 2008, 10:20

Fuzzer wrote:I wanna reiterate, If somebody is building this the same as the schematic, keep in mind that the electrolytic capacitor used in the LED swithcing is backwards.

Haven't used the LED switching

Is the schematic correct? As it NEEDS a buffer to sound right

JHS · Post by **JHS** » 22 Dec 2008, 09:07

The schem is OK.
With the correct IC and gainpot setting it's a very musical and natural sounding fullrange boost.
I mainly use it with a Marshall amp, sometimes a BF Fender amp, and a vintage Strat. IMHO it's way better compared to a SHO and other 1-trannie boosters running on 9V. A very good booster for goosing up a distorting amp w/o destroying the distortion structure of the amp. I think, due to a bit more compression and slightly more bass the RB2 is a bit better with BF amps, the RB1 for Brit. amps.

JHS

Bernardduur · Post by **Bernardduur** » 22 Dec 2008, 10:34

Thanks!

I really like this booster; in combination with my Dumble and my Tele it really can make the OD channel sing a bit more. But the extra bass really irritates me sometimes. With a buffer it sounds a bit more open and lacks the mud it'll give without one.

On bass I also use one now without an buffer.

Barcode · Post by **Barcode** » 23 Dec 2008, 04:49

I've been mulling over this schem and i am totally confused by the LED status section. What is the need? since the way the switching appears in the schem you would still need a 3pdt switch, why the unconventional wiring? And, if i'm not mistaken, you could omit all but the power filtering from that lower section of the schem, right?

Fuzzer · Post by **Fuzzer** » 23 Dec 2008, 19:58

You don't need that section at all, just wire the LED the way you have always done; off course, you still need the third pole switch.

Barcode · Post by **Barcode** » 24 Dec 2008, 00:33

Here is a layout with the LED part removed. I left the supply cap and diode in place as well as the voltage divider, the rest is removed from the power section. Let me know if you see anything wrong.

Manfred · Post by **Manfred** » 26 Apr 2018, 14:24

I had a Booster III which has been dissected.

marshmellow · Post by **marshmellow** » 26 Apr 2018, 23:51

That must be the worst design I've seen in quite a while. Thanks for posting anyway

. How somebody can mess up even the simplest of circuits that bad is just mind-boggling.

Manfred · Post by **Manfred** » 28 Apr 2018, 00:03

I found a error in my schematic, the values of the electrolyte capacitor had been interchanged.
Here the corrected schematic:

I create a single side PCB with an added potentiometer option:

BoosterSinglesSidedPCB.pdf: (5.11 KiB) Downloaded 64 times

BoosterSinglesSidedPCB_mirrored.pdf: (5.1 KiB) Downloaded 58 times

SprintLayout6-file:

HaoBooster.zip: (37.83 KiB) Downloaded 85 times

Manfred · Post by **Manfred** » 28 Apr 2018, 06:38

marshmellow wrote:That must be the worst design I've seen in quite a while. Thanks for posting anyway . How somebody can mess up even the simplest of circuits that bad is just mind-boggling.

Ok, what are your points of criticism?

marshmellow · Post by **marshmellow** » 28 Apr 2018, 10:07

Low input impedance. This will seriously load down the guitar pickup if it is directly connected and remove much of the harmonic content. If it's another pedal before it, chances are it will decrease the level a fair bit and decrease the SNR. Should be 500k-2M.
Unused opamp half, this is bad practice (here is why). Either use a single TL071, connect it to VR and configure it as a buffer, or use it to drive VR for the other opamp half. Leaving it unterminated is simply wrong.
High impedance NFB and gain setting network. Absolutely unnecessarily high impedances, all that is achieved by that is again worse SNR. Divide all resistances by a factor of 100, increase the caps by the same factor.
100k output resistor. Does nothing but reduce level and again decrease SNR. It makes up a voltage divider with the pot and the connected effect or amp after that. This big output impedance is in conjunction with the following cable capacitance a serious lowpass filter. 100R-1k is a proper value.
The level pot. Again no reason to use such a big value. Same reasons as listed for the 100k resistor. A TL07x can easily drive 2k load to full level, no need to use big impedances. 10k or even 5k is more appropriate.
The LED switching. Not sure what the point of all those parts is, pop reduction when switching? If that is the case, an easier solution is to use a simple CCS.

Sorry if my earlier post came across as critiquing your efforts Manfred. I really appreciate all your posts, simulations and the many reengineered pedals!

Manfred · Post by **Manfred** » 29 Apr 2018, 01:58

Sorry if my earlier post came across as critiquing your efforts Manfred. I really appreciate all your posts, simulations and the many reengineered pedals!

Don't get me wrong, I don't feel myself under criticism I am was only very interressted in your point of criticism concerns the circuit.
I would like to thank you for listing out facts and the link, very interesting, I greatly appreciate that.

I think this is the purpose of the forum to to learn from each other.

Low input impedance.... , Unused opamp half...

It could be considered to insert a impedance converter using the unused opam half,
that allows to solve both problems.

The LED switching...

As you guessed the LED circuit suppresses switching pop noise, applied in other HOA circuits too.

I can follow your other arguments too.
As always, the pedal works fine.

marshmellow · Post by **marshmellow** » 29 Apr 2018, 07:11

Sure it will work. But why not strive for better?

Manfred · Post by **Manfred** » 29 Apr 2018, 08:59

marshmellow wrote:Sure it will work. But why not strive for better?

I fully agree with you.

Intripped · Post by **Intripped** » 29 Apr 2018, 16:19

marshmellow wrote:
High impedance NFB and gain setting network. Absolutely unnecessarily high impedances, all that is achieved by that is again worse SNR. Divide all resistances by a factor of 100, increase the caps by the same factor.

My knowledge is too poor to discuss about it,
but i've just noticed that the NFB and gain network of the MXR D+ is very similar.

does it mean that MXR also did a bad job, or is that a different situation?

please don't get me wrong, i've really appreciated your post, i just want to better understand this point. thanks!