John Warren

Thanks Dave. For the amps here, the bottom sections needed refinishing. There's an autobody nearby that will refinish (paint, powder coat) anything made of metal. The paint used here is an acrylic urethane automotive paint (a satin topcoat). After paint is applied, the parts are hung in a benchtop IR oven. Tougher than what a rattle can applied paint provides. The difference between this method and a rattle can approach is the hardness of the paint. Even using a rattle can, an hour or so under the IR improves the durability of the paint. I like the paint shop but I've found another that specializes in small jobs like this and the turnaround is a few days rather than a few weeks. I'll be bringing a set of transformers from a Citation II to them to powder coat in that oddly cool brown color. They match paints using fancy machines and lasers.

In the first post, there's a link to a thread showing photos.

jc- Don't be amazed, the chassis tops are reproductions sourced from Korea. The quality is excellent. The bottom sections were reworked at a local metal refinisher I use. Does enamels, powder coat, anodize, acrylics. And the Korean supplier does make a chrome on stainless chassis top section for the MC225. They have a large collection of top sections reproductions. They've been making them for some time. Fair amount of work goes into the restoration. Most of the hardware is replaced which it should be it's over 60 years old! Good to see the amps in use! Interesting song selection. jw

Thanks gents!

Quite pleased with the end results.

Working an interesting project which I'll detail in the link below. MC30 pair for restoration (northreadingeng.com)

Agree with your assessment. I would not purchase a McIntosh product today. McIntosh's best days are behind them.

A few photos of a tube amp project completed recently. Two channels, about 20WRMS/ch into 8Ohms. Based somewhat on the Scott 299C output stage but using a solid-state, HV power supply design capable of substantially more power than is required for the push-pull 7591 pairs. Chassis CAD files were sent out for quote, the supplier (New England based) responded with pricing for larger quantities than I was considering. Placed an order for a small lot of chassis assemblies. All metal chassis assemblies are best for RFI/EMI/noise immunity. The chassis assembly is the high-cost item in the build. Uses oversized Hammond or Lundahl output transformers. Still waiting on a few finishing touches (knobs, graphics). Was considering silk screening the top plate but perhaps some other time.

Water should be either deionized or distilled. A friend of mine uses distilled water and Simple Green surfactant solution. It's alcohol based. Chemical smell. The u/s cleaners that sweep the frequency clean better than those that sit at a single frequency. With the surfactant and swept frequency embedded particles can usually be extracted.

It may be possible to remove the transducers from the plastic horn section and find ones that would fit. Can you provide photos of the rear of the assembly and, if possible, remove the transducers so we can have a peek?

The WSJ had an article that talks to the concept of "health-span" rather than life-span. Health-span is the years one lives with good health and free of diseases that impact your quality of life and state of mind. The years past when the health-span ends are the years spent managing disease. Most medical interventions, especially for the 75+ crowd, increase life-span but not health-span.

Common in industrial locations. If you have a portable water pump, wet-vac or using power tools in wet areas this is what you want. If you work on vintage, old and/or faulty electronics, lots of "gotchas" and surprises. Here's my take, connect chassis directly to panel Earth. Regarding Variac, the red, Chinese Amazon units are the POS. Can't run at rated kVA without getting hot AF. Wipers aren't accurate or don't function until the wick is turned halfway up then wham! The internal winding is likely a better fuse than the fuse. A Staco 12A variable transformer runs about $650 and will source 1.4kVA all day and barely get warm.

Texas Instruments published a 2-stage, phono preamplifier design based on the LM833. Flat RIAA response with noise floor lower than -100dBV. Can be fabricated for about 60 USD at the board level.

Are you running long cables at line level signals?

It's Damping, not Dampening.