bogen conversion
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dannysgrandpa
- Posts: 5
- Joined: Sun Dec 16, 2007 6:06 am
- Location: Vancouver, WA
bogen conversion
How hard will it be to convert an MX60A for guitar? Am I getting in over my head? Is it worth doing? I'm very adept in electronics but have yet to tackle something this big. Thanks in advance! Bill
When 900 yrs. old you are, look so good you will not! YODA
Re: bogen conversion
Go for it Danny... 
Jimi wanted all of us experienced...
You can do it!!!
Jimi wanted all of us experienced...
You can do it!!!
Re: bogen conversion
I am not familiar with that particulara model, but I am currently converting a Bogen E-10. Old PA conversions are fun. They take some planning as space is often very limited. The E-10 is quite small. But if the iron is good, and it usually is, you can end up with a really nice amp and a very satisfying experience.
How about some pictures of the guts?
How about some pictures of the guts?
Re: bogen conversion
How hard will it be to convert an MX60A for guitar? Am I getting in over my head? Is it worth doing? I'm very adept in electronics but have yet to tackle something this big. Thanks in advance! Bill
Many a bogen has been rebuilt in my day (ha, ha) in all honesty look at it this way, it's better to strip the amp and build it up from scratch verses looking at it as a converstion. The end results will sound and feel better, oddly enough it takes less time.
Hope it helps
Trace
Many a bogen has been rebuilt in my day (ha, ha) in all honesty look at it this way, it's better to strip the amp and build it up from scratch verses looking at it as a converstion. The end results will sound and feel better, oddly enough it takes less time.
Hope it helps
Trace
Last edited by Trace on Wed Jan 09, 2008 12:59 am, edited 1 time in total.
Re: bogen conversion
Exactly!
I've "converted" a Lafayette PA to Matchless Spifire. I've also converted a Brentwood to a Z-28. I am currently converting the Bogen E-10 to a hybrid Princenton AMp/Princenton Reverb (without the reverb or trem, but with a couple of mods).
In all cases, I gutted and rebuilt from scratch, using some parts, and some irn, and adding new parts as requirealways build wiht a hand wired board, so space and layout can be a critical. This is what makes it interesting and also challenging, and when it works out well, it is a very happy day indeed.
I've "converted" a Lafayette PA to Matchless Spifire. I've also converted a Brentwood to a Z-28. I am currently converting the Bogen E-10 to a hybrid Princenton AMp/Princenton Reverb (without the reverb or trem, but with a couple of mods).
In all cases, I gutted and rebuilt from scratch, using some parts, and some irn, and adding new parts as requirealways build wiht a hand wired board, so space and layout can be a critical. This is what makes it interesting and also challenging, and when it works out well, it is a very happy day indeed.
Re: bogen conversion
i also think re-gutting is better.
Starting on a new chassis with the old parts will give a better result.
Starting on a new chassis with the old parts will give a better result.
Re: bogen conversion
Gut and rebuild is easier for the simple reason that all will be known to you. Rework is a challenge. Ask yourself, why are you doing this? If rework is entertainment for you, why not? If tedious, then gut.
Re: bogen conversion
I converted a 1941 bogen e14.It taught me about tube amps.Its a pp 6l6
amp that is probably the best sounding that I have ever owned.
The drawback is I have a chb 100 chassis,and now I must! build another.
amp that is probably the best sounding that I have ever owned.
The drawback is I have a chb 100 chassis,and now I must! build another.
Re: bogen conversion
I converted a 1941 bogen e14.It taught me about tube amps.Its a pp 6l6
amp that is probably the best sounding that I have ever owned.
The drawback is I have a chb 100 chassis,and now I must! build another.
amp that is probably the best sounding that I have ever owned.
The drawback is I have a chb 100 chassis,and now I must! build another.
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sad mafioso
- Posts: 2
- Joined: Wed May 04, 2005 11:15 pm
Re: bogen conversion
I rebuilt one of these into a more-or-less Sunn Sorado/200S.
This is the only vintage PA rebuild that I've done, but I think it may be more involving than some of the other old stuff out there. Besides the usual things to look for in old gear, here are a few things to note:
The 8417s that came in the Bogen are no longer in production and NOS are fairly expensive. I now use KT88s. I never measured the OT primary impedance, but I'm guessing it's somewhere around 4-5k.
If you keep the voltage doubler power supply, you'll end up with a B+ of about 550-575v. You can tap off the middle of the cap stack for the screen supply like they did in the original. With KT88s, this makes about 100 watts. You could also go with a full wave bridge for a B+ of about 300-325v. If I went this route, I'd probably do something with 6V6s.
The original amp combined the power tube bias supply with a series chain for all the preamp tubes. I didn't like this, so I used the 6.3v winding for everything. I really have no idea how much current the 6.3v tap is rated for, but I only added one tube, and the PT doesn't seem abnormally hot.
There's no choke, and not a whole lot of room to add one, either. Not necessarily a bad thing, though.
I moved the power switch to the back panel next to the fuse holder, as the original had AC wires running back and forth across the chassis, which I didn't like. Conveniently, the chassis cutout for the extra AC outlet is the same size as many of the slide switches on the amp.
I didn't really find a convenient place to put a standby switch without either having long wire runs or drilling a hole in the (hefty) chassis, so I left it out. There might be some more space on the back panel, or maybe something could be done with that goofy circle on the front. I don't really miss having a standby switch, so I didn't bother.
As for the sound, the clean is very nice. The amp's natural overdrive is so-so, but I suspect that might be because most of the amp is basically a Dynaco MkIII. Here is a guts shot of what mine looks like now. It's messy, but apart from the transformer coupled hum, it's pretty quiet.
This is the only vintage PA rebuild that I've done, but I think it may be more involving than some of the other old stuff out there. Besides the usual things to look for in old gear, here are a few things to note:
The 8417s that came in the Bogen are no longer in production and NOS are fairly expensive. I now use KT88s. I never measured the OT primary impedance, but I'm guessing it's somewhere around 4-5k.
If you keep the voltage doubler power supply, you'll end up with a B+ of about 550-575v. You can tap off the middle of the cap stack for the screen supply like they did in the original. With KT88s, this makes about 100 watts. You could also go with a full wave bridge for a B+ of about 300-325v. If I went this route, I'd probably do something with 6V6s.
The original amp combined the power tube bias supply with a series chain for all the preamp tubes. I didn't like this, so I used the 6.3v winding for everything. I really have no idea how much current the 6.3v tap is rated for, but I only added one tube, and the PT doesn't seem abnormally hot.
There's no choke, and not a whole lot of room to add one, either. Not necessarily a bad thing, though.
I moved the power switch to the back panel next to the fuse holder, as the original had AC wires running back and forth across the chassis, which I didn't like. Conveniently, the chassis cutout for the extra AC outlet is the same size as many of the slide switches on the amp.
I didn't really find a convenient place to put a standby switch without either having long wire runs or drilling a hole in the (hefty) chassis, so I left it out. There might be some more space on the back panel, or maybe something could be done with that goofy circle on the front. I don't really miss having a standby switch, so I didn't bother.
As for the sound, the clean is very nice. The amp's natural overdrive is so-so, but I suspect that might be because most of the amp is basically a Dynaco MkIII. Here is a guts shot of what mine looks like now. It's messy, but apart from the transformer coupled hum, it's pretty quiet.