Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on April 01, 2020, 03:01:13 am

Title: JDH ice cube super
Post by: Leevi on April 01, 2020, 03:01:13 am

Does anyone have idea how this effect is implemented?
I think the reverb tank is partly bypassed which causes extra gain but how does the reverb work at the same time?

https://reverb.com/item/267473-jhd-super-cube-ii-1970s-boost-for-fender-reverb-amps-price-drop (https://reverb.com/item/267473-jhd-super-cube-ii-1970s-boost-for-fender-reverb-amps-price-drop)


/Leevi

Title: Re: JDH ice cube super
Post by: Latole on April 01, 2020, 03:19:01 am

This gadget have some inputs/ outputs picture don't show.

Google may have the answer ;

https://shop.guitarpoint.de/en/Effektgeraete/Diverse/JHD-Super-cube-II-Boost-/-Reverb
https://www.tdpri.com/threads/jhd-ice-cube-sustain-coupler-vintage-fender-specific.78627/

Title: Re: JDH ice cube super
Post by: Leevi on April 01, 2020, 03:40:49 am

Thanks Latole for the links.
I made a proto of it and noticed that the distortion works by using a resistor parallel with the tank but the reverb disappears.
/Leevi

Title: Re: JDH ice cube super
Post by: sluckey on April 01, 2020, 06:43:47 am

It's just a pot (and maybe a resistor) that's connected across the reverb tank. Turn the pot one way and the high resistance that's parallel to the tank has little effect, therefore the reverb works as normal. Turn the pot the other way and the low resistance shunts the guitar signal around the tank. The reverb pot will then act like a boost control. Sounded pretty shitty. Even a $20 distortion pedal sounded better.

Title: Re: JDH ice cube super
Post by: Leevi on April 01, 2020, 07:54:34 am

I have tried it with pot also with separate pots on both tracks (bypass and reverb) and the reverb signal disappears even if you have a high bypass resistor value like 2M. It might be dependant on the amp as well. If you add some small  resistance on the reverb track the reverb is totally useless. I'm testing with a vintage Super Reverb 1965.
/Leevi

Title: Re: JDH ice cube super
Post by: sluckey on April 01, 2020, 08:48:34 am

I'm not sure what you have wired up but if you connect the pot as shown it should behave as I described.

Title: Re: JDH ice cube super
Post by: shooter on April 01, 2020, 09:14:57 am

Quote

I'm testing with a vintage Super Reverb 1965.

fwiw
You probably know this, the "market" likes those amps un-molested, even the 2 prone is worth more.  when I fixed the last one my hands weren't shaking, but I was very conscience of "perceived value" effect of my work.

Title: Re: JDH ice cube super
Post by: Leevi on April 01, 2020, 09:19:35 am

Yes, the connection you sent works with distortion but the reverb is very weak.
The setup I tried is in the pic.
/Leevi

Title: Re: JDH ice cube super
Post by: Bantam on April 05, 2020, 07:17:50 pm

Slukey is right, and I'll toss in my two cents... Come to think of it that's all that thing is worth,  they do sound crap. But then again it's a PC world and tone is in the ears of the beholder!