anyone added 2x8's to a bandmaster reverb head?
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adbrunner
Jan 6, 2011, 9:18:45 PM1/6/11
to The Amp Guide
Considering creating a custom baffle to add 2 8's to the cabinet of my
77 bandmaster reverb head. Anybody have experience with anything
similar? Considerations, etc?
I like the idea of a the mod being reversible. can still plug into my
2X12 cab whenever I want, but can also pack up and go to a smaller
jams with just the (incredibly heavy) head. would keep the original
baffle and could easily swap it back to restore to original setup.
77 bandmaster reverb head. Anybody have experience with anything
similar? Considerations, etc?
I like the idea of a the mod being reversible. can still plug into my
2X12 cab whenever I want, but can also pack up and go to a smaller
jams with just the (incredibly heavy) head. would keep the original
baffle and could easily swap it back to restore to original setup.
Geoff
Jan 7, 2011, 12:55:37 PM1/7/11
to The Amp Guide
Why not? Unless you can afford a ton of equipment, you have to work
with what you've got. I have a 67 Bandmaster head which I currently
use with a one 12" Celestian. I would definitely consider slapping an
8"x10" combo or 2 10" combo together before going with two eights
tho. I'd like to know how it works out if you do it. Good luck.
with what you've got. I have a 67 Bandmaster head which I currently
use with a one 12" Celestian. I would definitely consider slapping an
8"x10" combo or 2 10" combo together before going with two eights
tho. I'd like to know how it works out if you do it. Good luck.
B L
Jan 7, 2011, 2:36:14 PM1/7/11
to the-am...@googlegroups.com
You know, you MIGHT be able to squeeze in a couple D208' JBL's in there... that would be ultra-cool...a pair in parallel would probably stand about 30 watts without blowing up. Unfortunately, they're sometimes hard to find and usually they are rather costly...but they would be very efficient and would be a much better choice than most modern 8" low power speakers. The nice thing about the D208 is that it is an alnico magnet, so they are not big and heavy like the typical late model ceramic magnet stuff.
While you are building your frankenstien monster, you MIGHT also consider a closed baffle design with a port, to extend the LF response of the speakers a bit, as well as to provide a bit of damping to keep them from bottoming out so badly on bass notes. That would extend the speaker life significantly and help the tone too. If you were able to port it to extend the bottom end down to about 120 hz, that would really give you some bang for the buck, coupled with those D208's, which are very efficient at about 95db per watt. You could wire the D208 in parallel to get the 8ohm load you want.
Lots of ways to go with this.
As far as clearance, I do think there may be a clearance problem with the OPT and/or PT unless you offset the speakers in some clever and unorthodox fashion. that might include front loading the baffle plate. That would gain you 3/4" additional transformer clearance. Of course, you'd have to be willing to come up with some other method of grille cloth mounting as well, since to front load you'd have to accept that your grille would be stapled over the front mounted speakers, making removal for service and/or replacement somewhat more challenging. I've done this very thing on a Princeton, both when I installed 12" speakers in a replacement baffle board, and when I put 2 (two) 10" speakers in a Princeton. (really... and I have the pictures to prove it!) The world's first and only 2x10 Princeton. it works great too.
Anyway...cool mod idea. Hope you make it work!
Cheers,
CoolBlueGlow
The Arkansas Tube King
While you are building your frankenstien monster, you MIGHT also consider a closed baffle design with a port, to extend the LF response of the speakers a bit, as well as to provide a bit of damping to keep them from bottoming out so badly on bass notes. That would extend the speaker life significantly and help the tone too. If you were able to port it to extend the bottom end down to about 120 hz, that would really give you some bang for the buck, coupled with those D208's, which are very efficient at about 95db per watt. You could wire the D208 in parallel to get the 8ohm load you want.
Lots of ways to go with this.
As far as clearance, I do think there may be a clearance problem with the OPT and/or PT unless you offset the speakers in some clever and unorthodox fashion. that might include front loading the baffle plate. That would gain you 3/4" additional transformer clearance. Of course, you'd have to be willing to come up with some other method of grille cloth mounting as well, since to front load you'd have to accept that your grille would be stapled over the front mounted speakers, making removal for service and/or replacement somewhat more challenging. I've done this very thing on a Princeton, both when I installed 12" speakers in a replacement baffle board, and when I put 2 (two) 10" speakers in a Princeton. (really... and I have the pictures to prove it!) The world's first and only 2x10 Princeton. it works great too.
Anyway...cool mod idea. Hope you make it work!
Cheers,
CoolBlueGlow
The Arkansas Tube King
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Stratopastor
Jan 9, 2011, 10:11:51 AM1/9/11
to The Amp Guide
(obvious point but I haven't seen anyone else say it) If you're
considering the closed-back approach, don't forget to ventilate the
tubes. Also, in extreme cases, speaker magnets too close to tubes can
pull the electron beam off-true, making the sound weedy.
considering the closed-back approach, don't forget to ventilate the
tubes. Also, in extreme cases, speaker magnets too close to tubes can
pull the electron beam off-true, making the sound weedy.
frank
Jan 9, 2011, 10:50:45 AM1/9/11
to the-am...@googlegroups.com
there was a dual showman reverb listed on ebay a few times a year or two ago with just such a mod. it was in nj. i did not go hear it. it never sold, if i recall.
> wrote: > Considering creating a custom baffle to add 2 8's to the cabinet of my > 77 bandmaster reverb head. Anybody have experience with anything > similar? Considerations, etc? > > I like the idea of a the mod being reversible. can still plug into my > 2X12 cab whenever I want, but can also pack up and go to a smaller > jams with just the (incredibly heavy) head. would keep the original > baffle and could easily swap it back to restore to original setup. -- You received this message because you are subscribed to "The Amp Guide" group. Thank you for your support. www.ampwares.com www.mojotone.com www.guitarandampshow.com
B L
Jan 10, 2011, 7:24:24 AM1/10/11
to the-am...@googlegroups.com
re "tube cooling" Yes, I've faced this before, and got around it by specifically designing the port locations to maximize airflow. While it may seem counterintuitive, since the port size is going to be smaller than you might expect, it is important to remember that one can use two smaller ports (one top, one bottom) to create convection airflow. As long as the total port size and length is correct, the port performance will be identical. There are many Theile Small calculators online which can easily determine the correct numbers. I also add a small low speed fan to aid in cooling airflow in the direction of the convection.
As far as magnetic deflection, that's why I recommend the JBL D208. There is no appreciable stray magnetic flux leakage in the JBL D or K series, due to the design of the magnet. They were designed that way to increase efficiency, but the happy byproduct is that they are free of stray magnetism issues.
Cheers,
coolblueglow
The Arkansas Tube King
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