Search found 190 matches

by bmxguitarsbmx
13 May 2020, 22:15
Forum: Amplifiers
Topic: How to improve tube amplifier tone by changing one part
Replies: 101
Views: 5761

Re: How to improve tube amplifier tone by changing one part

Approaching everything as a skeptic is a good example of a common bias we can all succumb to. Nothing to do with bias. Lack of bias is not a bias, just as atheism is not a religion. Approaching everything as a skeptic, as you put it, is what science is at its very heart. If a physical phenomenon ca...
by bmxguitarsbmx
13 May 2020, 00:43
Forum: Amplifiers
Topic: How to improve tube amplifier tone by changing one part
Replies: 101
Views: 5761

Re: How to improve tube amplifier tone by changing one part

Frequency response analysis uses an averaging process. So, if the capacitors are effecting the transient response, then that will be integrated in as only a small percentage of the entire samples that are averaged. As an example, the transient may last0.5ms (Maybe less than a full cycle of wave befo...
by bmxguitarsbmx
02 May 2020, 01:57
Forum: Boutique Stompboxes dissected...
Topic: Death By Audio - Optical Compressor [traced]
Replies: 6
Views: 2053

Re: Death By Audio - Compressor [traced]

Yeah your ideas are good. At least put the (+) input at 4.5v. I do tend to not try to drive current into bias supplies. Though, there may be some magic to doing so. Given that you may end up changing the current limiting resistor to control the LED brightness, I would tend to Put a large electrolyti...
by bmxguitarsbmx
29 Apr 2020, 01:09
Forum: Boutique Stompboxes dissected...
Topic: Death By Audio - Optical Compressor [traced]
Replies: 6
Views: 2053

Re: Death By Audio - Compressor [traced]

That circuit looks workable. Like a very simple "Feed Forward" Compressor. 1) 741 loop gain uses B1M+ 100k against the input impedance of your guitar to determine actual gain. This could be unruly/unpredictable. Or just plain awesome! 2) I think the OPTO LED/resistor should go to the same potential ...
by bmxguitarsbmx
19 Apr 2020, 03:25
Forum: DIY Stompbox designs
Topic: Stupid and easy question
Replies: 3
Views: 535

Re: Stupid and easy question

A log Treble pot will make the amp seem dark. Or, you can use a log treble pot on a very bright amp to make it seem even in the top end. I have accidentally installed a 250k Log pot in a Marshall based build and the customer came back complaining about how dark it was. Only changing the pot to linea...
by bmxguitarsbmx
05 Apr 2020, 07:16
Forum: DIY Stompbox designs
Topic: The Beatdown: A True MIAB
Replies: 12
Views: 1498

Re: The Beatdown: A True MIAB

Scaling the tonestack is a cool idea, but, there is only a gain of 4.7 after the tonestack so it will be small.
by bmxguitarsbmx
02 Apr 2020, 01:26
Forum: DIY Stompbox designs
Topic: The Beatdown: A True MIAB
Replies: 12
Views: 1498

Re: The Beatdown: A True MIAB

Sounds killer Ripthorn! Thanks for the scheme and the clips! Some of those early Marshall solidstate amps did sound awesome 8)
by bmxguitarsbmx
03 Mar 2020, 17:25
Forum: Amplifiers
Topic: Valve jr power transformer for push pull amp?
Replies: 11
Views: 955

Re: Valve jr power transformer for push pull amp?

Ok. Just as long as you know you can bias a Class AB el84 much colder than 90mA, which is totally out of range for the VJr PT. I've built a lot of amps in my day and while the ac30 is a legend, I don't prefer hot bias. I rarely ever think that biasing hot sounds better. The AC30 power section is ove...
by bmxguitarsbmx
03 Mar 2020, 03:29
Forum: Amplifiers
Topic: Valve jr power transformer for push pull amp?
Replies: 11
Views: 955

Re: Valve jr power transformer for push pull amp?

Go for it. Class A amplifiers use more than 2x the current of Push Pull amplifiers. Change the output transformer, add another of the same output tube, and let it rip. Cathode bias amps usually have large bias current keeping the tubes very much in class A at medium output.... Which means almost th...
by bmxguitarsbmx
02 Mar 2020, 02:19
Forum: Amplifiers
Topic: Valve jr power transformer for push pull amp?
Replies: 11
Views: 955

Re: Valve jr power transformer for push pull amp?

If you are planning on replacing the output transformer and the power transformer, you should just start a clean build.
by bmxguitarsbmx
02 Mar 2020, 02:11
Forum: DIY Stompbox designs
Topic: BAJA Splawn Quick Rod style Overdrive 160220
Replies: 24
Views: 3078

Re: BAJA Splawn Quick Rod style Overdrive 160220

Perfect. It is still useful to know that they are not real, and if you have real Toshiba transistors, they are good to save for low noise projects (Or sell haha)
by bmxguitarsbmx
01 Mar 2020, 01:21
Forum: Amplifiers
Topic: Valve jr power transformer for push pull amp?
Replies: 11
Views: 955

Re: Valve jr power transformer for push pull amp?

Go for it. Class A amplifiers use more than 2x the current of Push Pull amplifiers. Change the output transformer, add another of the same output tube, and let it rip.
by bmxguitarsbmx
01 Mar 2020, 01:16
Forum: DIY Stompbox designs
Topic: BAJA Splawn Quick Rod style Overdrive 160220
Replies: 24
Views: 3078

Re: BAJA Splawn Quick Rod style Overdrive 160220

Those are Fakes, not Toshiba transistors. I have a few piles of fake Toshiba's from china. They won't get close to the low noise or high Forward Transfer Admittance. At least for the 2sk117. I have noticed some nice offerings in surface mount form that are still available. The 2sk209 may be a 2sk117...
by bmxguitarsbmx
29 Feb 2020, 00:54
Forum: DIY Stompbox designs
Topic: BAJA Splawn Quick Rod style Overdrive 160220
Replies: 24
Views: 3078

Re: BAJA Splawn Quick Rod style Overdrive 160220

Toshiba jfets are hard to come by. I horde them and can't imagine squandering any on switching. YMMV :D
by bmxguitarsbmx
26 Feb 2020, 19:36
Forum: Unverified projects
Topic: 5W Chip Amp
Replies: 3
Views: 168

Re: 5W Chip Amp

Interesting find. I wonder how this thing overdrives. I, like Manfred, highly recommend current feedback to keep SS amps from sounding boring. A resistor in series with the speaker may also help bring out the tone.
by bmxguitarsbmx
10 Feb 2020, 20:19
Forum: Pedal Debugging & Troubleshooting Support
Topic: Adding a Feedback Loop - Input/Output out of Phase
Replies: 1
Views: 399

Re: Adding a Feedback Loop - Input/Output out of Phase

A strip board layout is for communicating a way to manufacture a circuit. What you want is to create a Schematic. A Schematic communicates the functionality of the circuit.
by bmxguitarsbmx
08 Feb 2020, 18:01
Forum: Stuff Seen for Sale
Topic: Why?
Replies: 6
Views: 1536

Re: Why?

I know, right?! Why is it so cheap? Is it broken?
by bmxguitarsbmx
09 Jan 2020, 20:17
Forum: Amplifiers
Topic: Madamp M15MK1 build help....
Replies: 20
Views: 4313

Re: Amp build help....

Alex's idea is a good one. For a quick solution, swap your tubes around until you get one that doesn't conduct any grid current. Grid current can start to flow at low plate voltages, but your design has plate voltages that should be ok for a majority of tubes out there.
by bmxguitarsbmx
07 Jan 2020, 02:26
Forum: Pedal Debugging & Troubleshooting Support
Topic: Mint 1981 TS9 sounds gated at max drive [SOLVED]
Replies: 10
Views: 301

Re: Mint 1981 TS9 sounds gated at max drive [SOLVED]

Check all op-amp pins for bias. +in,-in, and output Should all be at ~4.5V

Then check the bias of your transistors.
by bmxguitarsbmx
12 Dec 2019, 18:16
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Harley Benton - PA100 Power Attenuator [schematic]
Replies: 30
Views: 12585

Re: Harley Benton - PA100 Power Attenuator [schematic]

I got that explanation from you Phatt! It's in the Jet city Jettennuator thread. Makes a lot of sense. In fact, it may be 10x power/Octave to reach the same dB level. Like the "Bass player should buy a 1000Watt head to keep up with the guitarists 100watt head" rule.