Bluetooth KOSS Resto-modded headphones!
OK these are just beyond sick! Wireless Bluetooth version of my Resto-modded Koss DJ Headphones! And they’re switchable from Bluetooth to wired connection! A removable cord is realized with a mini-DIN plug. The cord features a holder for the 1/4″…
Keep readingNow in stock: Beige Koss Pro4/AA Resto-Modded DJ Headphones!
Folks, it doesn’t get more 70s than this! And they sound better than most modern headphones.
Keep readingNow in stock: One pair of Resto-Modded Koss Pro 5/LC in BLACK!
Get them while you can! A beige pair of Pro4/A is coming soon too
Keep readingKoss ESP/6A Resto-Modded DJ headphones, with Bass-Beat-Blinking LEDs!
I’m reaching absurd levels of over-the-top with these Koss DJ headphones! LOL I found these ESP6a’s for cheap and in great condition. Then I gutted them, and modified them in the same manner as my Koss Pro4/AA. It’s kind of…
Keep readingResto-modded Koss DJ Headphones now in BLACK!
OK, these are just too gorgeous! These beauties are Koss Pro/5LC, and are basically the same headphone as the Koss Pro/4AA that I resto-modded in a previous blog post. The Pro5/LC has a squared-off earcup instead of domed, and features…
Keep readingThe Koss DJ Headphones, now with a locking headband! (Article has been extensively updated.)
Updated article: Koss Pro4/AA Headphones resto-modded into great DJ Headphones! Why don’t all DJ headphones do this? I’ve installed a locking mechanism to the headband on my Koss resto-modded DJ headphones! No more fumbling to adjust while I’m playing. If…
Keep readingKoss Pro4/AA Headphones resto-modded into great DJ Headphones!
Did you know that stereo headphones for personal music listening, were invented right here in Wisconsin? In 1958, John C. Koss, and engineer Martin Lange, Jr. invented the Koss SP/3, as an accessory to a new stereo portable record player.…
Keep readingA GFA-555 customer success story. Audio-Precision verified performance!
Hi Chris! I bought some refurb stuff from you a couple years ago to rebuild an old 555. I got the input board and the soft start power supply. I just wanted to circle back and tell you how it’s…
Keep readingA “Nigel’s Speed Controller” for a friend
My buddy Tim has a Lenco turntable with a synchronous AC motor, and paid me to build this “Nigel’s Speed Controller”. Basically, it’s an AC power re-generator that produces a much cleaner AC power supply. A low-distortion sine wave generator…
Keep readingHoppe’s Brain Do-Over Policy
Has this happened to you? You’re installing or testing a Hoppe’s Brain PCB and the magic smoke gets out somehow? It happens to every tech, including me, see below. (Backwards transistor, oops.) This is a bummer, and a lot of…
Keep readingNEC 2SD746 / 2SB706 to TO-3P adapters are live!
Replace those weird NEC 2SD746/B706 transistors with your choice of TO-3P or TO-247 transistor without compromising thermal performance! These are used in Pioneer SX 80-series receivers, some Phase Linear, MCS and Luxman amplifiers.
Keep readingTO-3 to TO-3P Adapters / Heat-Spreaders are live!
Replace a TO-3 transistor with your choice of TO-3P or TO-247 transistor without compromising thermal performance! Looks cool too.
Keep readingValidating the performance of my TO-3 to TO-3P transistor adapters
Logically, I believe my adapters must have better thermal performance than simply bolting a TO-3P straight to a heatsink drilled for TO-3. There is simply more copper heat-spreader, and more surface area in contact with the heatsink. And the double-thick…
Keep readingA Marantz 1060 with Sanken Outputs!
I’m trying out my new TO-3 to TO-3P adapters on this Marantz 1060 that’s been sitting around my shop, 90% complete for the last few years. They look so cool! I think these Sanken 2SC4468’s —that I found in my…
Keep readingTO-66 to TO-220 Adapters coming soon!
Got another one! TO-66’s are even harder to get replacements for than TO-3. Again the usual solution is to bodge a TO-220 in place, but the TO-220 tab is much smaller than the TO-66 case, the thermal performance is not…
Keep readingTO-3 and “BatWing” transistor adapters coming soon!
On the heels of the launch of my MT-200 Adapters, these solid copper adapter plates adapt new transistors to old formats. Available soon! I just need to test them, but there’s zero reason they won’t meet expectations. Actually these adapters…
Keep readingMT-200 to TO-3P adapters are live!
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…
Keep readingXRayTonyB video about Hoppe’s Brain MT-200 adapters
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.
Keep readingValidating the performance of my MT-200 transistor adapters
Testing the thermal performance of my transistor adapters. (TO-3P to MT-200 and 2SD746/2SB706 packages for Pioneer receivers.) UPDATE: 2024.03.03 They’re now available in the Hoppe’s Brain Shop! The MT-200 package has terrific thermal performance, due to their large copper heat-spreader.…
Keep readingADCOM BOMs is live!
What other upgrades should I make to my amplifier? Here ya go ADCOM BOMs. This is everything I do in spreadsheet form.
Keep readingSpectral Audio DMC-10 Restoration (Send me more gear like this please!)
One of my first Hoppe’s Brain customers sent me this beautiful old preamp to work on. Eight years ago I had refurbished for him, a pair of Adcom GFA-565’s to drive a pair of power-hungry Eminent Technology EFT-8 planar speakers.…
Keep readingNew product teaser; MT-200 to TO-3P output transistor adapters!
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…
Keep readingA new test jig for the BFA-555
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…
Keep readingHow to never lose your 1/4″ to 1/8″ headphone adapter, ever, ever again.
An old 1/4″ jack, a little dremelling, shrink wrap and zip ties…
Keep readingReplacement 1/4″ phone jacks for DBX compressors, EQs, vocal processors, etc…
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…
Keep readingA few pictures of a GFA-555 MKI without “The Works”
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…
Keep readingInteresting phenomena visualized. Electric fields attract dust!
Dust is attracted to electric fields, and sticks to a board in a way that reveals the shape of the electric field in one plane. Dramatically illustrated here on the underside of an Adcom GFA-555. These dusty traces are at…
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