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Many of us "of a certain age" had our first real hi-fi experience as a result of building dynakits. They were well-designed and, in kit form, cheap enough for a student or newly-wed to afford. The instruction booklets were well-written and illustrated. Darn near fool-proof. My first project was a Dynaco ST-35 tube amp that cost $45 including the tubes! A few years later I stepped up to the ST-120 and although some would argue the ST-35 was a "sweeter" little amp the 120 was pretty ground-breaking in its day. I eventually sold both (along with a PAT-4) but a couple of years ago I decided to get a used ST-120 to restore. CSP member John O'Hanlon helped me find some replacements for the big capacitors but the amp had other issues so I put it aside until a couple of weeks ago. I was looking for mods and upgrades (the 40+ year old design does have shortcomings) when I stumbled across a gold mine! http://www.updatemydynaco.com/ is a great site that offers a load of upgrades and improvements for the ST-120. Long story short: I ordered every possible upgrade (the "Full Monty"), leaving only the original chassis, power cord, binding posts and transformer. I opted to spend an extra $10 for the amp modules used the AkitikA GT-101 power amplifier. The difference between those and the regular ST-120 replacements: 0.1% versus 1% gain setting resistors, 10,000 uF output capacitors versus 3300 uF output capacitors. I also bought the new heat sinks (very nice but unnecessary), power supply upgrade, power supply and C12 caps and a blue LED mod for the power switch (purely cosmetic). The prices were very reasonable IMHO (total was under $200). I installed new RCA jacks and new feet that I had on hand but those are also available on the site. Delivery was FAST. All of the parts are high quality and the new printed circuit boards are well-made and clearly labeled. Instructions (available on the site) are as clear and complete as the original Dynaco manual. Best of all: The owner/designer Dan Joffe provides super-fast helpful tech support (I had made one bone-headed goof). So today I finished the amp and after bringing it up on a Variac (just a precaution) I gave it the real test: Powering the AR-3a's. The 3a's are supposedly power-hungry and at 4 ohms they pose a tricky load. I played a variety of music: Jazz, Rock, Classical (including organ) at decible levels WAY higher than normal. They sounded great. And the amp wasn't stressed at all. The heat sinks got barely tepid and there was no hint of clipping. According to Dan, the updated modules put out more than 50 Watts, but a shade less than 60 Watts into 8 Ohms and nearly 90 Watts into 4 Ohms. I plan to take the amp to my favorite tech for testing but to my ears it's all good. A few photos below of before & after, and the amp being auditioned. IMHO the updatemydynaco kits are true heirs to the Dynaco legacy and Dan Joffe may be the latter day David Hafler. And the tech support is incredible. If you have a tired old ST-120 do yourself a favor and update it with one or more of these modules. Don't have an ST-120? The AkitikA GT-101 provides the chassis and a modern torroidal transformer. Updatemydynaco also sells some modules and upgrades for the PAT-4 preamp, SCA-80 integrated amp and the mighty ST-400. Makes me sorry I sold my old PAT-4! I have no connection with this outfit--just a really satisfied customer. -Kent
Hi guys, i just scored a set of AR5's. They are in desperate need of some TLC. Woofers and mids are good, although the woofs need some new foam. Both front wired tweets have loose leads and need to be fixed. (In case that fails, i can go the Hi-Vi way.) But there is one thing that bothers me, those pots are dry AF. But really dry! I can't get any sound with those in the signalpath. I know that these things go fubar after 40+ years,but i don't tend to use tone controls anyway. My question is, is there a way to completely bypass the tone control pots on the AR5's.? And what do i need to do, which components in the crossover do need to be removed and which ones are supposed to stay to keep the speakers sound like they should? Of course i will do the whole shebang of revitalizing the xo with fresh film caps and new terminals.