Amp/Preamp Asylum

McAlister Audio

80.243.127.65

In Reply to: Re: Maybe -- maybe not posted by jmrdc on May 11, 2007 at 13:42:20

To follow up on your question about McAlister Audio.

I took delivery of a PP-160 and PL-12 preamp. The two are a lovely sounding combination. However, in building this equipment a number of construction mistakes were made:
1. The screws in the case to the power supply for the amp were drilled in a sloppy manner, some not even holding the case together, while others had been redrilled more than once. (I had the case repaired and mounting pieces were welded in the case.) 2. One of the transformers inside the power supply was flopping around on arrival. The bolts were loose. (The floppy transformer was attached to the case with new bolts and isolated with plastic).

3. The volume and balance pots were not grounded and caused a terrible hum when i touched them. They had been glued to the case because the builder did not take the time to counter sink the holes for the shfts, which could then be grounded with the usul locking nut to the case. The shft on one ws bent. (Chiseled old pots off and bought and installed new (better) pots properly grounded to case. Hum went away).
4. The wrong tube sockets were installed for the power tubes and the tubes wobbled. (Installed new sockets and rewired them of course).
5. The transformer covers on the power amp were put on unevenly with reference to the top of the unit. (Cosmetic only).
6. It was delivered with a bad premp tube. (Threw away)
7. The two units in combination had excessive gain, and the preamp volume was loud with the control at 7 o'clock. (Added dual attenuators)
8. Peter McAlister told me he listened to the amp for a number of hours before he sent it. Surely he would have discovered the hum from the preamp due to improper grounding of the pots.
9. It has cost me over $600 to get all this repaired.

The combo sounds lovely. He hand builds and hand winds his own transformers. Everyone who saw them, said they were beautifully made and rugged.

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