Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: isaac_teller on March 09, 2022, 01:37:23 am

Title: Kalamazoo 2 tremolo intensity
Post by: isaac_teller on March 09, 2022, 01:37:23 am
Hello. I've built a clone of the Kalamazoo 2. Works great, sounds great. However there is no intensity control. What would I need to do to increase the intensity without adding a knob(fixed intensity level). Thank you.


https://schematicheaven.net/bargainbin/kalamazoo_m2s.pdf

Title: Re: Kalamazoo 2 tremolo intensity
Post by: sluckey on March 09, 2022, 05:05:57 am
There may not be any very simple mod because your circuit is already delivering all the tremolo it can. You can try replacing R5 and C13 with a red LED. This will definitely make the tremolo stronger but may not work in your circuit. Easy to try.

You have a spare triode. Look at some circuits like the Supro 6622 (https://el34world.com/charts/Schematics/files/Supro/Supro_s6622.pdf). You can set the strength of the tremolo by changing the value of the 220K grid resistor for V4-7.
Title: Re: Kalamazoo 2 tremolo intensity
Post by: tubeswell on March 09, 2022, 10:59:12 am
What about increasing the plate resistor to 220k (to get more gain)?
Title: Re: Kalamazoo 2 tremolo intensity
Post by: isaac_teller on March 09, 2022, 11:08:34 am
That sounds like a good idea. I'll try it.
Title: Re: Kalamazoo 2 tremolo intensity
Post by: PRR on March 09, 2022, 03:20:38 pm
I doubt "increasing gain" will get you there.

Is this really using 1-1/2 12AX7s?? What could you do with the odd triode? Seems like Fender had some buffered trem drive.
Title: Re: Kalamazoo 2 tremolo intensity
Post by: shooter on March 09, 2022, 05:04:43 pm
^^^^
good call, I looked n checked the box that both 1/2's were used, missed that 1st tube  :laugh:
Title: Re: Kalamazoo 2 tremolo intensity
Post by: isaac_teller on March 10, 2022, 12:43:12 am
The version I built used a 6AV6 for the tremolo. There's no unused triode. I lowered V1A cathode resistor to 1K5. It sounds better to my ears.
Title: Re: Kalamazoo 2 tremolo intensity
Post by: sluckey on March 10, 2022, 04:47:49 am
The version I built used a 6AV6 for the tremolo. There's no unused triode. I lowered V1A cathode resistor to 1K5. It sounds better to my ears.
That kind of info should have been included in your first post.