Just FYI, the anode resistance of the E88CC is guaranteed to be 8.2k not 82K. It is advisable to use a 5Watt type.

The virtual 600 ohm impedance via serial R solution on the secondary siden of the output transformer made me a bit surprised though. It should be wound to 600 Ohms with a tap at 200 Ohms. But then you have to wind the transformer by hand.

Thanks for creating this page!

Are you suggesting that the ‘Gain Trim’ circuit is unnecessary? Would you omit on future builds or simply that it’s not intended to be used as a gain control, but useful if using multiple preamp channels in stereo configurations or ?

Lastly, when you say you would build future builds using two 2P3T switches before and after the i/o transformers, do mean physically & mechanically directly before and after the i/o transformers?

Cheers

Hi Tyler. What makes you think that? I built this thing so long ago that i certainly can’t recall, but it did work GREAT…. 82K is a MUCH more likely value for a plate-load resistor than 8.2K, given the biasing configuration of the tube ETC. I am not saying you are wrong, I am just saying that plate load resistors in R/C coupled amplifiers are generally 75K to 330K. Please share your insights tho, I am no expert. CR

Hi Andres. I can’t recall building this thing, as it was so long ago, but based on the fact that the supply is an unventilated box, i would assume it was diodes. Likely basic IN4007 diodes, either a pair or a quad (depending on whether the PT H/V secondary is center-tapped or not).

what rectifier did you use in the project? or do you use diodes for PSU ?

Do these builds have tone and character of like the Chandler Limited TG 2 or his version of the Reds 47? What are the be best resources for this type of build for Diy? I’ve looked at Seventh Circle Audio N72. I would love to use a unit like this on vocals and acoustic than run to audio interface than daw. After watching so many mic pre type, i.e. op amps, tube outboard, emulation mic pres, it seems these give the most in your face vocal signal and that would cut through a mix with analog smoothness and rich tone for classic rock like Rolling Stones,Beatle and Queen to name a few. Thank you for any info and should I look into Drip electronics? Another tone searching nut, Zach.

Hi Pete,

needless to say you’re work is perfection here. I wonder if you’re considering to make this project market-able.
Do you think “someone” can ask for a quote to buy one? BUILT! 🙂

This would be an awesome piece of gear for both project or pro-studios. Thanks. Alex