future guitar amp donor

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future guitar amp donor

Postby nyazzip » Thu Feb 17, 2011 11:44 am

just received this today! another Lafayette....this one is a "LA-218 Monophonic Amplifier". i made an 18 watt marshall clone last year out of a very similar lafayette, and i plan on doing the same with this one. the previous owner has already modified it for phone jack in/output, but that appears to be the extent of it. sounds like crap as-is, with no headroom.
aside from some coupling caps, i shouldn't need to buy anything else...
i love these power transformers that have solder tabs instead of wires! why did they ever get away from that design?
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Postby EWBrown » Thu Feb 17, 2011 7:39 pm

That amp may have actually been a Kenwood (or Trio, its earlier incarnation). Lafayette branded tube gear was often from this source in the late 1950s and 1960s. THat amp definitely has the right "look" to it, and it has a strong family resemblance to a Trio tube mono FM tuner I found at a junque shop a couple years ago.

Back in the early 1960s, I had a Lafayette 4 band, 8 tube AM / SW receiver kit which also was sold under the Kenwood/Trio label as a finished product. I forgot the model number but the main and bandspread dials were like " C D " side by side. The receiver worked very well, but several years of service in a tropical sea-side climate seriiously did it in, due to salt air and high humidity-caused corrosion.
THe receiver had the same gray "dog bone" resistors and white caps, and the power trannie looks nearly identical - if in fact it isn-t the same one, just used in a different application.

As I recall, its power trannie also had the solder tabs instead of wire leads. I was still a solder-slinger-in-training back then, so my Dad helped me along the way (he did most of the soldering, I did the mechanical assembly and installed the components, pre-soldering.
It worked upon initial powe-up though it did need a bit of fine-tuning & tweaking of the alignment of the RF and IF stages to get it working properly.

/ed B
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Postby nyazzip » Sat Feb 19, 2011 12:47 am

i noticed finally today as i was tearing the amp down, one of the PP pair is an "8BQ5"....supposed to be 2xel84/6bq5....maybe thats why it sounds so bad :))
i dunno what year its from but i'm guessing sometime after 1961, based on comparison to the '61 Lafayette LA-55 i made into a guitar amp awhile ago. the smaller caps are "Lily" brand, and the "dogbone" resistors are "River" brand. one of the 2 can caps is branded "Nitto/Nitto Chikudenki"; the other one is illegible but seemingly different.
all tube sockets and terminal strips are fixed with heavy zinc-ish looking rivets...
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Postby EWBrown » Sat Feb 19, 2011 8:49 pm

An 8BQ5 would have very low emission with 6.3V on the filament, and the PP operation would be seriously unbalanced...

However, that should not cause any damage, other than to the sound quality.

For what is often considered as being"cheap" amp, it does have a fairly large OPT, my Knight 928 has two relatively puny-sized PP OPTs.

The early '60s Japanese gear had a lot of now-unfamiliar component manufacturers' names. Their grasp on the English language was often tenuous, and very inventive, at best ;) (lol) The same could be said for instruction manuals from China, and other non-English speaking nations, today.

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