The Amp Garage

SS has poor shear rating, by comparison. You hope things never take that hard a knock, but I'd rather the fasteners not be stainless if it happens. Stand up transformers take that most of that torsional force in a spin.. *POP* Dunno, buddy.. I like softer metal. SS is more brittle than normal steel...

I don't perceive that the tone of my FluxTone changes as the field coil voltage is lowered; it's not fizzy at low settings. With the Fluxtone, when you turn down the field coil voltage, does it start to add distortion especially to the low notes? I don't perceive that such an effect is occurring; n...

This falls into the realm of justification for Mercury Magnetics pricing. Fluxtone has high cost to build the speakers. They are machining the iron flux path, and also winding a large electromagnet. Then they are buying OEM speaker cone parts with some arrangement from the original speaker manufact...

There's no snake oil discernible to me? If it's important to hear to true sound of a cranked amp but at a controllable sound pressure level, then it seems to be the best option. It's unfortunate the price has risen so much in the past few years. However, my Model 10 is best sounding and most useful...

It's a field coil speaker with a variable voltage supply to control field strength. He uses OEM parts for the basket/cone/spider. I have the Celestion Gold version. I bought it about 5 years ago for about 1/2 the price he has listed now. It's a good sounding speaker. The attenuation works well down...

I've played a Magnatone M8 with the single stage vibrato and compared to my M13 with the two stage vibrato. The extra stage is definitely an improvement.

Thanks very much Tim for spending the time to compile all this information. This will make a great addition to my "Magnatone File".

Kagliostro wrote:The schematic repeat the values imprinted on the capacitors

47k is old notation and mean 0.047 (or 47000pf)

K

OK, thanks.

Also, your notation of cap values is written like they are resistors. That is confusing, as we don't know the units. For example 47K for a cap value or 10K for a cap value. How many microfarads or nanofarads or picofarads etc.?

A varistor for a maggie has a very high resistance if measured by meter. I inferred from the SiC article that a high NTC was achievable with low resistance devices - perhaps your 120 ohm measure part was of that type. Unless the part is in a bag marked with a model number then the only way to tell ...

http://dalmura.com.au/projects/Silicon%20Carbide%20Varistors.pdf The link is a good reference for old tech SiC devices like the Workman parts. The old maggie varistor is best referred to as a ceramic part, rather than a semiconductor, as it is the granular interface that dictates performance. That ...

No, they are different. A thermistor is a temperature dependent resistor, and a varistor is a semiconductor. Both are used to limit surge currents, but a varistor does it by shorting (to protect against a voltage surge or spike), and a negative temperature coefficient (NTC) thermistor is typically ...

We're they perhaps thermistors? Maybe they are thermistors. The reason I'm confused is that Workman parts are labeled FR or FS, and some are labeled varistors and some are labeled thermistors. For example, FS308 is labeled as a Varistor 1.0 Ma @ 110 volts. FS1205 Varistor .05 ma @ 80 volts. FS927 V...

A little more information on the field coil voltage supply. I used a Hammond step down transformer 166G80, and then this adjustable DC voltage module that is based on the TL783CKCSE3 linear voltage regulator - AudioWind Electronics-Salon Model SP-4.

http://www.audiowind.com/pdf/sp-4.pdf

Maybe I can help you guys out? I bought 3 vintage field coil speakers to experiment. Two of them are Jensen F12N and one is a Rola 12 inch. They all have 1.75 inch diameter voice coils. The field coil DC resistance for each is in the range of 680-700 ohms, and they all came from a Hammond organ. Ham...