Bell & Howell Filmosound 179

[xtian]

Damn that 6V6 is shoved right up against the PT. That can be a source of hummmm.

No kidding, Cliff! Also it heats the PT up nicely. Really pleasant on a cold winter's evening.

[wsaraceni]

I wouldn't pay $900 for that. I have amps that people would say the same thing about if they saw the insides. But when they hear them, they try to buy 'em anyways!

this amp is even cleaner looking inside than the at mars specialist i had. but i'd buy one of those again in a heartbeat. it was a great sounding amp.

the at mars was really weird feeling. it was almost as if your guitar strings were looser than they really were. not quite sure what that term would be. sag maybe? play a big open chord and it takes a second before you feel it come out. was really cool and a lot of fun. great sounding amp.

is yours anything like that?

[xtian]

Yes, definitely. If you dime it, there is noticeable sag.

[guiltless]

Did you end up getting the hum under control?

One thing that I have wondered about these amps, specifically the At Mars Specialist, is the claimed 15 watts. The power supply doesn't seem to be beefed up at all. The OT is relatively small. I know a Tweed Deluxe is in the 12watt range... so what makes these 15-18? Are we looking at something as simple as increased line voltage and a hot bias?

Thanks!!!

[xtian]

Too late! Sold it. I did not improve the hum, but overall it was not bad for such a compact amp. Seemed about as powerful as the two 18 watt marshall style amps I have. Had some interesting sag when dimed.

Was a good experience, but a major PITA to strip the original components out of the chassis.

[wsaraceni]

im currently trying to source two of these chassis. i loved my at mars so i plan on building one like that since i finally found my info from that and figure the other i'll do something different. I'm wondering if the transformer can support a pair of 12ax7s and a pair of el34s. where do you find the current draw for tubes? these originally had 3 6v6s and that other photo tube or whatever along with a pair of octal preamps and the rectifier.

[wsaraceni]

also, for the 6sl7 and 12aX7 pinouts. is this correct?

from - to
12ax7 - 6sl7
1 - 2
2 - 1
3 - 3
6 - 5
7 - 4
8 - 6

12ax7 4,5/9 heaters
6sl7 7/8 heaters

[wsaraceni]

i just took my "host" chassis apart. having a little trouble figuring out the color codes on the wire. whats the best way to go about finding it out without wrecking the PT and OT. the only cable i know for sure is the black one which they have going to the fuse and switch. the other two i "think" they had going to the power plug but i dont know for sure.

[surfsup]

If memory serves green are 6.3v windings, yellow are 5v rectifier windings and red are usually hv secondary. Though not sure if that is accurate for today let alone if any standard existed back when your trannie was built...

If the amp is assembled, what do the leads connect to? That should tell youright away...

[xtian]

The wires in my donor amp were so old that it was hard to distinguish between red, orange, yellow, brown. So I made careful notes and marked the wires BEFORE stripping the chassis.

For the OT, the primary side has brown, red, blue. The red is the CT. On the secondary, black is common, green is 16ohm, grey is 8ohm.

My notes on the PT are a little sketchy. On the primary, I have black and black w/red connected to 120vac, and black w/yellow don't use. On the secondary there are three sets: the yellow set of two wires is for the recto, the red set of three is HT with CT, and the remaining set is heater voltage with CT. These you can easily measure.

Good luck!

[wsaraceni]

thanks. the PT primaries are the ones im trying to figure out. i hope i can guess the right red black, power it up, and test the other leads.

[wsaraceni]

just got a 2nd chassis. hopefully i can figure out the color codes on these transformers a little better and use that to go back to the first.

[xtian]

Looking forward to photos of your finished amp!

[jujudubluz]

@xtian,

old post but going the same route - just cleaned a filmo chassis an try to figure out what to build ...
How did you came out with the single tone / single volume configuration ? Did you just delete channel one ?

Do you guys think it would be safe to build a 5B6 in there ? with 6v6 and 5y3 ... ?

cheers and happy new year !

[xtian]

Haw...I don't remember!