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Dear James,

What more can you tell us about the sealed Filtech filters
used in the Mk. VIB tuner?

What does "barely acceptable" mean? Does that mean these
filters were:

1) generally poor filters, even when "acceptable" OR
2) a small percentage were quite good but a lot
were rejected at the SAE factory OR
3) The best ones just barely met the spec (but
the spec was a good spec to meet to begin with)

Since they are sealed, can these be "unsealed"? Are
the filters potted with epoxy (say it isn't so!) or
soldered shut or both? Does Filtech exist any longer?

Do you think the problem with the filters is design or just
poor quality control at the Filtech factory or both?

Best regards,

Paul Bigelow

Dear Paul,
Firstly, the filters are potted, sorry about that, and then the can is
soldered. They wanted to make life difficult for others to find out what
they were doing. Yes we had to weed out the bad ones and that's all I'll
say. No they weren't bad filters but they were not of supreme performance
either. There were two filters: one was a six pole and the other was a four
pole. Barely acceptable means just that in that the selectivity was barely
acceptable, certainly not in the league of the Marantz 10B. But then nothing
at that time was in the league of the 10B except the forthcoming Sequerra
tuner which came out (finally) in 1975. Ed Miller was a supherb RF engineer
but was under the gun to get something to market for a reasonable price.
Everyone know what happened to Marantz because of the cost overruns on the
10B. So to be sure, the Mark VIB was a good tuner however, for another $1000
retail, it could have been much better. I don't think Morris would have
slept very well if that were the case as sales might have been meager. So in
the final analysis, the VIB represented the best that could be done for that
money at the time. Be awares that the Sequerra tuner which came out about 2
years later started out at $3300 and quickly escalated to $12,500. Need I
say more?
James Bongiorno

Paul Anthony Bigelow wrote: