FOUND two kits in storage: Reduction Preamp and S.E.X. v2.1 - Advice needed!...

[tachyhon]

Hello!,
I joined this forum when I bought these kits many years ago, but never got around to building them. I am curious if they should be built stock or if there were any major changes in the designs that should implemented during the build process. Is it safe to think the caps are still good?

...I am no expert on tube amps, but enjoy working on them and have saved many by replacing old capacitors and blown resistors. Despite being able to read schematics, I really don't understand how circuits work and how swapping out certain components will alter the performance - but I am handy with a soldering iron and have enough OCD in my veins to achieve nice results.

Reduction Phono Preamp Kit
S.E.X. v2.1 Kit
S.E.X. 2.1 c4s (upgrade kit)

Not sure if it is relevant, but here is a list of the equipment that I have that would potentially be paired up with the Bottlehead stuff...
Technics 1200 (w/ Grado gold cartridge), Nakamichi CR1A tape deck, Grado Alessandro Headphones (38ohms), Goodmans Maximus 1 speakers (1960s version), Eico HF-12 mono blocks, Magnavox 8610 ('flea' 3.8w stereo power amp).

I am also interested in building a pair of high efficiency speaker cabinets, like the ones that use Fostex 4" drivers with a back loaded horn. Would love to get feedback on those as well.

 

[bucketofguts]

You have come to the right place. Welcome aboard!

 

[Paul Birkeland]

I'd order 10 new HLMP-6000 LEDs, as they can absorb moisture over time, and soldering one that has absorbed moisture can damage it.

I don't see any red flags with the equipment you intend to use with this gear, though I'd want to wire the SEX amp for 4 ohm operation on Grado headphones.

I'm not sure a 4" driver in a back loaded horn would be considered a high efficiency speaker, you'll probably land somewhere around 88dB for sensitivity, but that may be plenty if you're not in a huge room and you don't really crank things up.

 

[tachyhon]

I'd order 10 new HLMP-6000 LEDs, as they can absorb moisture over time, and soldering one that has absorbed moisture can damage it.

I don't see any red flags with the equipment you intend to use with this gear, though I'd want to wire the SEX amp for 4 ohm operation on Grado headphones.

I'm not sure a 4" driver in a back loaded horn would be considered a high efficiency speaker, you'll probably land somewhere around 88dB for sensitivity, but that may be plenty if you're not in a huge room and you don't really crank things up.

Cool, thanks for the advice! Is there a recommend wattage for that 4ohm resistor?
…You are right about the speaker not being high efficiency, I was looking at the Fostex FE103NV2 and misread the specs!
Do you know of any high efficiency speakers (or kits) that would make for a suitable pairing?

 

[Paul Birkeland]

There's no 4 ohm resistor. When you get to wiring the output transformers in the SEX amp, wire them for 4 ohm output.

I think you could try the Fostex speakers with the SEX amp, especially if you're using them in a relatively small room.

-PB