Hoppe's Brain

Introductory offer: FREE! (If you can help)

I need some help from my customers! I have not yet tested these adapters in any actual amplifiers or receivers. But I have every reason to believe they’ll work perfectly. If you succeed in installing these adapters in your amp or receiver, and can provide me with clear pictures of your install that I can use on this product page, and some user-experience feedback, you will receive a refund for your purchase, up to $45 (8 adapters). Also, if you find you cannot make them work, you’ll receive a refund. I can provide support though the process; you can call or email me about it. We’ll figure it out. If it doesn’t work, it doesn’t work, and that’s the deal. (But it’s probably gonna work.)

MT-200 to TO-3P / TO-247 Transistor Adapters / Heat-Spreaders

Check it out! Thanks Tony! I’m excited about this product, this really solves a lot of problems for people trying to fix 70s and 80s amps and receivers.

What other upgrades should I make to my amplifier? Here ya go ADCOM BOMs. This is everything I do in spreadsheet form.

UPDATE: 2024.03.03 They’re now available in the Hoppe’s Brain Shop!

Here’s a (literally) cool solution to replace those MT-200 output transistors in your vintage amp or receiver! These adapters equal the excellent thermal performance of MT-200 devices, using commonly available TO-3P or TO-247 transistors.

The entire adapter is solid copper all the way through; there is no insulating layer. The TO-3P transistor is simply surface-mount soldered to the adapter, using solder-paste and hot-air. The backplate (collector) is connected to the copper body of the adapter.

Continue reading New product teaser; MT-200 to TO-3P output transistor adapters!

I’ve been making new, more reliable test jigs for all the most popular boards I sell. This jig for the BFA-555 MK1 features a replica of the entire output section of a GFA-555, but with only one pair of output transistors. Obviously, you can’t run much power through this, but it’s all I need to prove the board works.

Pogo-pins meet target pads on the underside of the board under test.

An old 1/4″ jack, a little dremelling, shrink wrap and zip ties…

I’ll just put this here. My DBX 166A compressor had terribly corroded 1/4″ phone jacks, and I found these exact replacements with gold-plated contacts. Neutrik part number NRJ6HF-1-AU (Gold plated) or NRJ6HF (Silver plated). These jacks are used in many other DBX products.

Hey internet, I just finished refurbishing this GFA-555, and the customer opted to go without the BFA-555 Smart Soft-Start Power Supply, so if you’re wondering what you get without this option, here it is! I do install some Capacitor Hats to replace the crusty originals. The original power supply capacitors were replaced with Kemet ALS30, 22,000uF, which is about as big as you can go without a soft-start. (Or the switch will spark too much and the fuse may blow due to the in-rush current.)

Invoice on this one was $1210, which includes new Kemet power supply capacitors. Without the capacitors this is a $930 job.