18Watt.com

JimbpGaff wrote: ↑

Tue 05/12/20 2:58 am

Great info.

not sure if I missed it in the threads but is this for a 16 ohm load and how much attenuation will it give.
Jim

As Josh said, the attenuator will "work" for 4 and 8 ohm loads, but is best suited for 16. See the first page of this thread for a plot of impedance vs. attenuation.

Can I use a different value Rheostat ?
The 150 ohm 50 watt is hard to come by at the moment in the UK as they all seem to be on back order until the end of the year.
Jim

JimbpGaff wrote: ↑

Wed 05/20/20 12:36 am

Can I use a different value Rheostat ?
The 150 ohm 50 watt is hard to come by at the moment in the UK as they all seem to be on back order until the end of the year.
Jim

You can. Lower values will limit attenuation. Higher values will increase it at the expense of increasing impedance.

colossal wrote: ↑

Wed 05/20/20 8:05 am

JimbpGaff wrote: ↑

Wed 05/20/20 12:36 am

Can I use a different value Rheostat ?
The 150 ohm 50 watt is hard to come by at the moment in the UK as they all seem to be on back order until the end of the year.
Jim

You can. Lower values will limit attenuation. Higher values will increase it at the expense of increasing impedance.

Limiting attenuation isn't a bad thing, since there will be less tone sucking that way. BUT there's limited options in that price range. I looked at alternatives, and they get pretty expensive. The RJS125E for example is 125 ohms, and $80. Some other variations were hundreds of dollars.

Personally I got a couple of the RJS150Es on eBay for $40 a piece. There is a seller in the UK selling the 150 also, but not as cheap. The 125 is available on there too, but I dunno about in the UK.

Thanks,
Josh

Thanks Josh

Just found the one on ebay for $77.00.

A lot of money in these difficult times .

I will have to do some thinking .

The pure resistor attenuator is a cheaper option, But.....
Jim

JimbpGaff wrote: ↑

Thu 05/21/20 1:52 am

Thanks Josh

Just found the one on ebay for $77.00.

A lot of money in these difficult times .

I will have to do some thinking .

The pure resistor attenuator is a cheaper option, But.....
Jim

Yeah, it's not cheap. But it's only $14 more than Mouser sells it for if you can't wait for people to have it in stock. On the other hand, you could build this attenuator without the rheostat, and use the switched section until a better deal on the rheostat becomes available. You can increase the resistance for the lugs and have the switched section attenuate at higher levels in the meantime.

Thanks Josh.

I will do some thinking .
Jim

I'm building a Trainwreck-style attenuator right now and I decided to draw up 4 possible wiring possibilities as schematics. All 4 of these are electrically identical and it is the same circuit. the only difference is the wiring sequence in which R1 is connected in the circuit. I drew all 4 in bypass mode.

Josh posted my #1, "Attenuator Type 1" on 4/29/20 and I don't know the source; its R1 sequence is: Input, R1, Lorlin Switch Pins, "A" (On the Lorlin switch), then Ground.

Mehfuzhoss posted my #2, "TDPRI Layout" on 4/22/20 and I drew up the schematic from that layout; its R1 sequence is: Input, "A", Pins, R1, then Ground.

Katopan posted my #3, "JMP/Audiofanzine Layout" on 4/23/20 and I drew up the schematic from that; its R1 sequence is: Input, Pins, "A", R1, then Ground.

There is a fourth possibility I haven't ever seen, so I drew up #4, "Not Seen in the Wild". Its R1 sequence is Input, R1, "A", Pins, then Ground.

The R2, cap and rheostat structure is common to all four of these wiring possibilities.

[I noticed Josh drew his layout with pin 7 going to the wiper, it was just easier (and electrically the same) for me to draw 7 to the leg in the schematic.]

I drew up wiring diagrams for all 4 of these schematics, and I like the JMP/Audiofanzine setup the best -- mainly I like the simplicity of daisy-chaining pins 11-5 on the switch. Here is my wiring diagram for that. Note, if you align the centers of the switch and the Rheostat, and face pins 6/7 at the rheostat, the switch knob pointer will point at the pot control when selected (nice from a user interface perspective). With jacks on the short side and resistor mounts on the long sides, the switch and pot will be the only things poking through the face of the enclosure, which is nice for graphics. Mine is going inside a combo cabinet and I added an external speaker out jack to the output.

I cleaned up that Audiofanzine schematic a bit. You can use 6, 11 and 16 Ohm taps on R2; I decided to use 5, 11 and 17.

Here is the same circuit that JMP built and that I drew from the Audiofanzine picture. I found this schematic on The Amp Garage, it was posted by bnwitt, Sat May 07, 2011 at 11:15 pm in the "Airbrake schematic or layout" thread. This is identical to my schematic of the JMP layout, just a slightly different visual.

Honey Hush!

Quick Honey Hush Demo at https://www.youtube.com/watch?v=VaQbRbV544c

Honey loves her knobs. Big knobs, small knobs, whatever.
But which are the BEST knobs for Honey?

A) Blue Chickenhead

B) Silver Aluminum

C) Black Aluminum

D) Skirted Oven Dial

Definitely black aluminium for me.

I think D fits the motif best.

WOW, I just stumbled onto this thread. I just picked up the pieces for making two of these Airbrakes minus the rheostat only because they're not available. I'll likely build one up with the gold resistor in place of the stat for now. NICE examples. I was simply going to use the layout as posted in the very beginning of this thread, but would you recommend one of the others? Need to re-read this to find out.

The Honey Hush graphic is awesome, man!

ViperDoc wrote: ↑

Thu 10/01/20 5:59 pm

WOW, I just stumbled onto this thread. I just picked up the pieces for making two of these Airbrakes minus the rheostat only because they're not available. I'll likely build one up with the gold resistor in place of the stat for now. NICE examples. I was simply going to use the layout as posted in the very beginning of this thread, but would you recommend one of the others? Need to re-read this to find out.

The Honey Hush graphic is awesome, man!

This is the project doc I made for it: files/JMPGuitars_Break_Wind_Attenuator.pdf

ViperDoc wrote: ↑

Thu 10/01/20 5:59 pm

The Honey Hush graphic is awesome, man!

Thanks!

ViperDoc wrote: ↑

Thu 10/01/20 5:59 pm

I just picked up the pieces for making two of these Airbrakes minus the rheostat only because they're not available. I'll likely build one up with the gold resistor in place of the stat for now.

The next ones I build are only going to have the rheostat, the switch doesn't really do much sonically -- 2dB cuts are kind of worthless IMHO; it's once you get to the -10dB to -30dB range that actually accomplishes meaningful volume attenuation.