Tube amp design for the office

02County

AK Member
a guy at the office has one of those bose systems at the office, the kind with flashy little speakers and a sub under his desk. I’d like to bring an office system of my own, particularly a tube amp build from scratch. Since it’s the office, it needn’t be strong. I’ll likely run my phone through it so I may not need a preamp. I have some klh model 32 speakers that should clean up nicely. But I need an amp.

For parts, I have the power transformers from a Conn Minuet organ and another - an absolute hoss of a hunk of iron - from a Baldwin. I also have the output transformers and various other bits from a Maggie 185 chassis whose transformer went south.

Can anyone recommend a simple schematic or design? Much appreciated AK -
 
so you're thinking maybe 6V6 push-pull using the Magnavox 185 output transformers and whatever power trafo fits the bill? The lowest-hanging fruit suggestion is just build a 175 with whatever power transformer is closest to the right voltage, adapting as needed to get the voltages right. Maybe tack in a buffer stage and a volume control to make use of the extra tube socket that the 185 came with and give yourself some level control.
 
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or you use fuses and rely on good design principals to minimize risks.
 
I would build a Maggie 9300 series amp. If you want to go all out, build it in a new chassis. There is a build thread on here by DG that will make it even better. You wind up with an honest 15WPC and it uses the magical EL84 tubes. Can't go wrong.

BillWojo
 
And what happens if there's an accident involving your home made amplifier?
There are dangers everywhere. Driver a car is very dangerous and so is crossing the street. Yet we do those things on a daily basis multiple times with no consequences. Making a home made tube amp can be just as safe an inconsequential.
 
a guy at the office has one of those bose systems at the office, the kind with flashy little speakers and a sub under his desk. I’d like to bring an office system of my own, particularly a tube amp build from scratch. Since it’s the office, it needn’t be strong. I’ll likely run my phone through it so I may not need a preamp. I have some klh model 32 speakers that should clean up nicely. But I need an amp.

For parts, I have the power transformers from a Conn Minuet organ and another - an absolute hoss of a hunk of iron - from a Baldwin. I also have the output transformers and various other bits from a Maggie 185 chassis whose transformer went south.

Can anyone recommend a simple schematic or design? Much appreciated AK -
It is best to use the output transfromer in an amp design similar to the one it came from. The specs for the transformer has been determined by the circuit or the circuit was designed for the transformer. Of course, you have some leeway but, make sure you know your OPT specs which should closely match the spec of the OPT in whatever schematic you choose.
 
thats why I suggested just building a 175 from the transformers that came from a 175/185 amp. No need to tinker with the feedback, it should already be mostly ok. If someone has built an upgraded amp specifically around those transformers and has already established the circuit parameters, that also would be a solid option if the OP doesn't have the gear and experience to work that out for himself.
 
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