Deluxe Reverb Cathode Bias Mod

I recently completed a mod to my Deluxe Reverb Reissue to add a cathode bias mode. Overall it made the tone brighter and a little more raw, but didn’t make that much difference so I switched it back and forgot to take an internal picture in the complete state, but you can see part of the mod here:

I changed to a ClassicTone power transform which has a low power 300V primary along with the regular 330V. I used a 4PDT switch to switch between high power/standard bias, and low power cathode bias. Using the low power mode puts it inline with a Tweed Deluxe, so I used the same cathode resistor (250?) and bypass cap (25µF). I put the 4PDT switch in fuse slot, moved the fuse and power over and removed the standby switch. I disconnected the middle pin of the bias pot to do the mod, along with the respective pins on the power tubes, so no modification to the PCB was needed. I did need to drill extra holes though to fit the ClassicTone transformer, which is vintage spec.

Rough demo here, no comparison, just for posterity:

Comparing Google and AWS free instance performance

I was looking to host some websites and wondered if I could do it for free on either Google Cloud or AWS free instances. Google list their free instance as having 2 vCPUs, while AWS list only 1. However, since this is an arbitrary unit derived by the cloud service themselves, we don’t know if 2 vCPUs on Google is really faster than one on AWS

I wanted to use the service with the highest performance, so I decided to benchmark the two using sysbench. To my suprise Google was actually faster than AWS as you can see from the screenshots. Ultimately I found shared hosting to be higher performance in the real world, as you share a large powerful server with a lot of memory, so it can handle spikes in traffic better, and once I factored in backup and support costs, it made sense to just pay for that.



LG Ultrafine 4K daisy chain with 34WK95U-W

After my last post comparing these two monitors, I wanted to see if you could daisy chain the two and still only have to connect one cable to the MacBook, as the LG Ultrafine 4K supports 40gbps and has a thunderbolt out port as well.

Turns out that you can! Thunderbolt 40gbps from MacBook -> LG Ultrafine -> 20gbps to LG 34WK95U-W at full resolution on both monitors.

LG UltraFine 4K 24″ (Mac) vs. LG 34WK95U-W 5K2K 34″ Monitor

For a while now I’ve been using an LG UltraFine 4K (24MD4kL) monitor with my Apple MacBook. However I’ve wanted to have a little more desktop space and was able to get an LG 34WK95U-W UltraWide at a discount, so I thought I would share the differences between these two high pixel density monitors.

– Higher pixel density on the UltraFine, but the UltraWide is still retina like
– Clearing sounding speakers UltraFine, but the UltraWide is louder and much more useable than the built in 14″ MacBook’s
– Ultrafine is slightly brighter, and the semi-gloss screen is slightly more premium
– 3 USB-C ports on the UtraFine compared to 2 USB-A, but the UltraWide has HDMI/DisplayPort inputs and can display two sources at the same time
– UltraFine wakes from sleep faster
– Thunderbolt on the UlatrFine allows daisy-chaining to another 4K monitor
– Native Apple controls for volume an brightness on the LG UltraFine although you can use MonitorControl with the UltraWide
– Some people are annoyed by the fan noise on the UltraWide, but I couldn’t hear it
– About 1.5x more desktop space on the UltraWide
– UltraWide is almost twice the price

Overall, some people might be better off getting two UltraFine 4Ks instead of a single UlatrFine, since it’s almost twice the price, but I got my used and I already use the monitor on my MacBook as a second display as well as Touch ID and the webcam, so having 3 monitors was just too clumsy and took up too much space. I tend to work on just 2/3rds of the UltraFine, as I find two windows optimum as a programmer. But the extra third allows me to have space for email or a video without having to constantly cover my main work.

I had to do a few things to get my UlatrFine to work at high DPI resolutions.
– Update the monitor firmware using the LG OnScreen Control software downloadable here.

– Using the display menu on the monitor itself, change the Display Port version to 1.4. Again it wouldn’t show up as a 5120×2160 monitor without doing this.

More tips can be found on this MacRumors thread. I did not need to use SwitchResX or BetterDummy in order to run at 3840×1620 resolution.

Also while the UltraFine 4K is made for Mac, people have got it working on Windows machines with Thunderbolt, and the brightness can be controlled with one of these apps:

Small Improvements to the M1Pro MacBooks

The 14″ M1Pro MacBook is the best Mac I’ve ever owned. Having used one for some time now though, I would have liked to see a few small improvements:

  • Half size function keys but a larger touch pad
  • Menu bar come to exactly the bottom of the webcam notch
  • HDMI 2.1 and SDUC (SD Express Card)
  • Ethernet on the MagSafe charger (like the iMac)
  • USB-A Port (please just give us one Apple)
  • More key travel on the keyboard (it’s better than the butterfly keyboard, but I still prefer my old unibody MacBook keyboard)

The M1 iMac Should Have Been USB-C Powered

The new M1 iMac is sure to be a hit, but given its lower power processor, it would have been great to make it USB-C powered, so a power supply could be shared between the iMac, MacBook, and iPad, now all running the M1 processor. USB-C supports power along with data, so the ethernet on the power supply (which is a great idea.) could still be included and made available to the MacBook and iPad. It would have also allowed USB-C wall power sockets to start becoming a standard, which could also start including the ethernet connection, wired internally in the wall. At the very least it should have done a MagSafe connector which was the same as the MacBook, which is rumored (leaked!) to be on the M1X 14″ and 16″ models, scheduled for release mid-2021, but it looks like the connector for the iMac is far too big to work on a laptop.

M1 Mac Mini Internal Storage

Was looking at the M1 Mac Mini and wondering if you could fit some extra internal storage inside all that empty space. I’d love to see someone do this:

  • Add a USB to M.2 SSD in the extra space.
  • Take slim right angle cable out through the fan vent and plug it in a USB-C port out the back.
  • For the extra brave, maybe they could desolder one of the USB sockets, and attach the cable directly to the motherboard.

I realized this was probably more trouble than it’s worth when you could just stick a tiny 512GB USB, or maybe in in an M1X Mac Mini Pro use a 1TB SD card.

Princeton Blackface/Tweed Hybrid In One Amp

I’m planning to modify a hard-wired Princeton to be both a Blackface/Tweed (and maybe even Brownface) amp in one. The blackface mode will be 100% stock. I’ve been working from this guide here:

I’ll post more details here soon, but for now here is my draft layout:

Train Wreck Type-2 Lar-Mar on a Victory V40

I’ve been looking at doing a post phase inverter master volume mod to my ’68 Fender Vibrolux. I was wondering about using what was on the Victory V40, since it is a American-style tube amp. It turns out they seem to use a Type-2 Lar-Mar but with a larger value pot, and smaller value safety resistors.

I think the advantage of this setup is that with the resistors in parallel, the lower resistance makes more difference when calculating the total resistance. The better tolerance of the fixed resistors keeps the total grid leak resistors more consistent between the two power tubes, as pot tolerances can be ±10% of the stated value.

Here’s a comparison:
1) 10% tolerance 250K pot in parallel with 1M resistor:
Min = 225K x 1.0M / 225K x 1.0M = 184K
Max = 275K x 1.0M / 275K x 1.0M = 216K

2) 10% tolerence 1M pot in parallel with 250K resistor:
Min = 0.9M x 250K / 0.9M + 250K = 196K
Max = 1.1M x 250K / 1.1M + 250K = 204K

As you can see, even though the pot tolerance is the same, the end result is a much smaller deviation between the 2 grid resistors with a 1M pot vs a 250K pot.