Amplifier Experts

05/19/2026

Just to let y'all know, I've started a YouTube channel, Offgrid Outlaw, catering to the issues of off grid living. First two episodes are up. I may be an engineer, but I come from a family of chicken farmers.

About independent living, generating your own electricity, drawing your own water and raising your own food via gardening and raising chickens.

05/18/2026

The Raven Reflection amplifier is up and running and sounding great.

Using an exclusive circuit design developed at Amplifier Experts, this Raven Reflection can finally unlock its full potential.The original design was cathode...

05/18/2026

Finally ready to sing. The Raven Audio Reflection amplifier has gotten the AE magic treatment.
Switched from cathode bias to fixed bias
Added a negative DC power supply (via the unused winding)
Added in the Signal Responsive Dynamic Bias circuitry to both channels.
This is how to maximize music power in an amplifier whose power supply sags badly under load.
Before modifications: Idle power 255W, max signal power 295W
After modification: Idle power 149W, max signal power 450W
Before modification: Output power 32W at clipping, THD 7% @ 30W.
After modification, 43 watts per channel continuous, both channels driven, 62W per channel, short term power out (before power supply voltage sag) with 0.7% THD at onset of clipping.
Amp runs cooler, power tubes run cooler as a result of these mods.
Can't wait to move it to the studio and hook up some speakers. Need help moving this beast.

05/15/2026

Finally got this puppy up and running. Found a few tubes in the wrong sockets, so switching them improved performance. But it's a cathode-biased amplifier, and as such, it leaves a lot of performance on the table.
I've discussed with the owner, and been given the green light to make improvements:

Switch from cathode bias to dynamic bias with grounded cathodes
Use the unused medium voltage tap to create a bias supply
Add my proprietary signal responsive dynamic biasing circuit.

Currently the amplifier makes about 25 wpc at 5% THD. I expect we should get close to 80 wpc and down to 1% THD after the upgrades.

05/13/2026

Progress on the Raven Reflection amp. Got power transformer mounted. Got capacitor PCB mounted and wired in (top side). Figured out the winding configuration with an ohmmeter and wired up the ones that make sense. But there are two extra windings, one medium voltage and one low voltage, for which there seem to be no destination connections.
I was a bit shocked to find the output transformers are generic Hammond 1650 transformers. You'd think they'd put something exotic in there for a $16K amplifier.

05/11/2026

The Raven Audio amplifier is missing it's entire power supply. My task is to install new power transformer, power supply rectifier/filter components, figure out where every cut wire goes without any sort of schematic, and make it work again.
I love a challenge!

03/21/2026

A cool running tube amplifier. Plate temperatures normally run close to 400°F on conventionally-biased amplifiers.
This is my own design, with a servo-balanced phase inverter and Signal-Responsive Dynamic Biasing circuit. The power tubes idle nice and cool, extending tube life, and reducing electricity waste.

03/19/2026

The story of Peter Aczel, and The Audio Critic. I used to receive his magazine in the late 1970s.
My last contact with Peter was sending him a copy of my first recording of the Greater Bridgeport Symphony Orchestra, for his honest comments and feedback. I got a glowing review.

https://youtu.be/W4q2qgDxKQg?si=Kr46oUM5skX5TZGU

03/15/2026

This Sansui G6000 had a dead tuner. Problem was traced to no power to the tuner, because a break in the clad of the PCB between TR604 and ZD601 caused there to be no reference voltage for the pass transistor which relies on this reference to produce output. Trace repaired, tuner is alive!

03/04/2026

Did you know...
That setting transistor amplifier output stage idle current on a distortion analyzer can often yield lower idle power consumption and allow the amplifier to run cooler?
Every Class AB amplifier has a 'sweet spot' --a point where the current at idle goes down before the small signal distortion starts to rise. We can find that sweet spot and often find a lower idle current than factory, without increased notch distortion.
For example, a receiver that was drawing 78 watts off the mains socket, draws just 29 watts after the idle current optimization.
The cooler amplifier will last longer and with rising electric bills, the owner will be able to enjoy hi-fi with a slightly smaller cost of operation.

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