Orpheum 700 Circuitry

23 03 2009

A real spaghetti junction!

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Point to point wiring.

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Just not all that orderly.

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Orpheum 700 Speaker

14 03 2009

When I pulled off the back of the Orpheum, I expected to find a Jensen speaker, as I’ve read they originally featured.

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But, as can be seen above, it was not to be!

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Researching the numbers, it appears that the speaker was made by The Best Company sometime in 1971, which makes it definitely a replacement speaker.

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Regardless of who made the speaker, it sounds great! It isn’t as smooth or as clean as a Jensen but in this case, that’s fine since I want a ratty blues grit coming out of the amp and the Best speaker delivers.

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I made another unexpected discovery when learning that one of the speaker wires is coming off the large electrolytic capacitator rather than both coming from the output transformer. This can be seen in the photo above as the leftmost cable of the pair of white wires heading off to the speaker.





Popping The Top On The Orpheum

8 03 2009

Time now to crack open the back of the Orpheum and see what lurks behind the 50 year old thin plywood.

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Three preamp valves guard the approaches to the tube bank; one Sovtek 7025, one blank ECC83 and one totally blank 12AX7.

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The output tubes are a pair of RCA 6V6GT valves and the rectifier is a RCA 5Y3GT. All the RCA tubes are marked “Radiotron Electron Tube”.

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Output Tube As Culprit In Lafayette Mystery?

19 01 2009

As the investigation into the Lafayette amp’s inability to function, startling new evidence has surfaced that could put an end to this riveting mystery.

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Scotland Yard spokesman Neil Yarmouth was quoted as saying “It looks like the output tube has flamed out.” Investigators won’t confirm reports that the tube was simply 40 years old and failed due to old age but recent photographs suggest that is exactly what happened.

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Lafayette Amp Tone And Volume Pots

13 01 2009

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Some good closeups of the pots and input jacks.

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Also a good perspective on the power transformer and a big electrolytic capacitor.

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Lifting The Lafayette Lid: Tubes

29 12 2008

Taking the chassis out of the Lafayette yields a nice view of the circuit.

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The three tubes are plainly seen; two 12AX7 s, one shielded and one not along with the taller 6BQ5.

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The could be the original tubes but are very, very old in any case.  They are all marked “Hitachi Japan”.

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It’s a fairly clean chassis with a good bit of room between components except the circuit board is a bit crammed.





Lafayette Front Panel: Nobs And Jacks

15 12 2008

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As mentioned before, a former owner played around with the Lafayette’s control nobs and I’m not too sure if either style on there now is what was on the amp originally.

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The fat silver nobs look like they came off a hi-fi stereo tuner?