#40 in BF Princeton Reverb Chassis w/Old Bassman Iron

[David Root]

Getting close to completing my #124 build, already planning next one!

Has anyone done one of these??

I have a BFPR cabinet I had custom built 2" deeper than standard and baffle cut for a 12" speaker, I was going to do a Gibson EH-150 with it but have changed my mind. It will be a sleeper because it's not black Tolex, it's aged tweed. Have a Mojotone steel chassis for it.

Also have two AB165 Bassmen, both late '67, one BF, one SF. Today I took a break from the #124 and took the iron out of the SF Bassman and measured it. (Checked it out in the amp before I pulled it. 448V on the plates and screens, pretty normal). OT Zpri is 2,180 ohms, a little higher than nominal but OK.

The iron will fit the Princeton chassis. I'm not sure yet if I can fit an Altec 417-8C or an EV or Emi Delta Pro 12A. Would like to put an Altec in it as I'm told #40 circuit likes Alnico speakers.

Anyone have any intel on whether these big speakers can be fitted without the OT interfering with the speaker, maybe move the OT on the diagonal??

[dreric]

It can be done.....................Princeton Reverb modified by Randy Smith @ Prune Music in Berkeley CA. Before Boogie was Boogie. I've never looked up the trannies but I don't think they are Princetons .

Eric

Sorry for the cobwebs and out-o-focus if you want me to look up the trannies let me know. I also have a very early Boogie (007) with fender iron and a 417. If I'm not mistaken they changed the layout from the chassis you have to accommodate the transformers. I could post photos if you are intrested.

[David Root]

Great stuff! Thank you for posting it. I would like to know what trannies were in that Princeton. I see a PT and a choke, but no OT, unless the choke is the OT and it is Princeton iron.

Please post pix of your Boogie too. How do you like the 417??

[Sonny ReVerb]

I think Pic #019 shows the OT and reverb trannie(?). Pic #018 shows the laydown PT. Probably no choke.

[martin manning]

My guess is the smallest transformer is for the reverb and the OT is the one with the green and black wires in front of it.

MPM

[dreric]

I poked around and the output transformer (above and the right of speaker midline) is a 125A6A (Bandmaster). The smallest (between the 9 pin tubes) is the reverb. I can't read the codes off the power transformer without pulling the chassis.

Legend has is that Randy gutted the Princeton innards re-wired ala bassman, upped the transformers and installed the 12. They were originally a novelty until Carlos comes in, plays and says "man that little thing really Boogies"

If there's enough interest I'll pull the chassis and we can look at the guts.

In terms of the 417. It's one of my faves, punchy and articulate like a JBL but without the icepick. Personally I kinda like them better than EV12Ls but they blow MUCH easier whereas its hard to hurt an EV

[David Root]

Thanx very for looking at that for me. The Bandmaster OT looks maybe smaller than the Bassman and has a different number (Bassman AB165 OT is 125A13A). Being designed as a bass amp it makes sense that its OT would be bigger than the Bandmaster. The PT is the same on both amps, 125P7D.
Edit: I checked the dwgs, 125A13A is bigger than 125A6A. 3/4 " higher and 4-hole instead of 2-hole. Wonder if it will fit with the Altec. Looking at my cabinet, the speaker cutout is moved off center towards the preamp end, so I may have to move the OT back closer to the PT. I think I need the speaker in hand before I locate the OT!

The Altec 417 is rated for 75W. This would be a 50W amp so it should be safe, yes?

[Bob-I]

The Altec 417 is rated for 75W. This would be a 50W amp so it should be safe, yes?

The Altec 417 is a 100 watt speaker. Mesa used them in 100 watt amps and they held up pretty damn good, better than JBL's, not quite as good as EVMs.

You'll be fine in the 50 watt amp.

[thyx]

The Altec 417 is rated for 75W. This would be a 50W amp so it should be safe, yes?

The Altec 417 is a 100 watt speaker.

Best be careful...a 417 is not always a 417. That is, there was more than one model. When the Boogie was originally created, the models were 417-8A, -8B, then -8C. The first two had curved supports, the -8C had angular ones. The photos of the Boogie above show the -8C model. It's a 75-watt speaker. Later, around '78 or so, they came out with the 417-8H. That model WAS capable of 100 watts...it also had a fiberglass former for the voice-coil instead of the paper one found on the earlier models, so it tended to sound more "ice-pickey" and harsh. Know which model you have before you hit it with 100 watts.

[David Root]

I printed the spec sheets off the altec website and that is correct, -8C is 75W, -8H is 100W. Someone else had told me the 100W sounded a tad different.

[David Root]

See below pic, the OT fits better than I had hoped. It is about 1mm off the speaker frame.

So, as I continue to try to get the fizz out of the OD on my #124 build, I will be cutting this chassis to accept the old Bassman iron.

I think I will cannibalize the AB165 chassis further and use the preamp sockets and shields. Maybe the PS board and the bias pot too.

Am I looking for trouble if I use the old PS board, and is it worthwhile tonewise?

[Sonny ReVerb]

Pretty tight. Will speaker excursion be an issue?

[David Root]

I wondered about that myself. The top of the transformer is back only a little from the cone, although most of the transformer projection is across the surround area. This is a 3" voice coil, how much do these old Altecs move the cone?

I just took a closer look. I can get my index finger in between the OT and the cone at the top of the transformer, so there is a good half inch space from the cone.

I hooked the speaker up to my 7-pin tweed Harvard clone. It is without doubt the sweetest speaker I ever heard!!