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Tone control bypass (Kontakt KT-7)

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Hello!

The story, i have a Kontakt KT-7 amplifier ( Class A Single ended)
I wasn't satisfied with the tone control. The bass was just too much (even when completely turned down)

So i came up with this. drawn it with my perfect paint skills (Attachment-1)
The high and mid improved dramatically but in the process i've lost almost all low tones. I think the cutoff frequency isn't right even tho 680nF should be enough?

Anyone who can help me out with this? And if my suspicious are right what kind of value would be more suitable? I'm a student on low budget so i rather not have to order 5 different kinds of values for experimentation.

I've also attached the complete diagram of my amplifier

(Please try to explain it to me like I'm a five year old. This isn't my first language)
 

Attachments

  • KT-7 BYPASS.jpg
    KT-7 BYPASS.jpg
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  • Kontakt KT-7 RIAA MD versie - kopie.jpg
    Kontakt KT-7 RIAA MD versie - kopie.jpg
    1,003.7 KB · Views: 203
Thanks for the answer.

The original had tone problems (bad caps). I've rebuild this amp but than without the tone control. The speakers are not the problem. i've tested them on multiple systems (solid state and another EL84 without tone as-well)

What you said about i might not have done what i think i have done.
I rechecked the volume pot (i've soldered all components on there)
The only think i could think of, 3th leg of the volume pot (ground) I've connected both resistors on that (L+R channel) and from there a wire to my groundpoint (star) located nearby the ECC83

Should i separate ground L and ground R? run a wire individually to my groundpoint?
Doesn't seem to me that could cause a problem. but hey,.. i've seen stranger things in my life
 
Update :

I feel so stupid.
Always check what you order online

Orange drop 683K... it should have been 684K
Last are the digits behind the value 4 = 68+0000 pF (680nF) and i got 68+000 pF (68nF)

Went searching in my storage, found some 224K's (orange drop) and yes my bass is back!
 
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