Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mike_J on February 26, 2021, 10:40:51 am

Title: Any audible impact on tone from shielded grid wires?
Post by: Mike_J on February 26, 2021, 10:40:51 am

The attached picture shows how I envision the jacks and wires would fit. Spent enough time on the shielded wire to hope the capacitance of the cable does not have an audible impact on the signal coming through the cable.


The cable lengths including an allowance for 3/4” for the lead length to the 68K resistors for V1a and V1b is 4” and 3-1/2”, respectively with a corresponding capacitance of 17 and 15pF respectively.


If it is not noticeable I will install them and think about them no more. However, if it would make an even one percent impact the wires are probably short enough and isolated enough to get away with straight wire. Then I would test the amp for soundness with the cables installed then change to straight wire as probably my first test.

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: thetragichero on February 26, 2021, 10:47:06 am

just put em in. only ground one end of the shielding (end at the input jack seems convenient enough)

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: Mike_J on February 26, 2021, 11:43:48 am

Quote from: thetragichero on February 26, 2021, 10:47:06 am

just put em in. only ground one end of the shielding (end at the input jack seems convenient enough)

Thanks. Already grounded on the input jacks end.

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: PRR on February 26, 2021, 02:43:31 pm

How long is the shield cable from guitar to amplifier?

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: Mike_J on February 26, 2021, 07:03:57 pm

Quote from: PRR on February 26, 2021, 02:43:31 pm

How long is the shield cable from guitar to amplifier?

Twenty feet and a lot more pF than in those short shielded grid cables if that is where you are pointing me towards.


Thanks
Mike


Made it pretty easy to understand.

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: pdf64 on February 27, 2021, 03:19:25 am

In that scenario, my particular OCD allows me to feel content with the 68k resistors moved to the valve socket, rather than being mounted at the jack.
From the photo I couldn’t make out if that’s how you’ve already done it.

Title: Re: Any audible impact on tone from shielded grid wires?
Post by: Mike_J on March 03, 2021, 03:01:40 pm

Quote from: pdf64 on February 27, 2021, 03:19:25 am

In that scenario, my particular OCD allows me to feel content with the 68k resistors moved to the valve socket, rather than being mounted at the jack.
From the photo I couldn’t make out if that’s how you’ve already done it.

They will be wired to the socket. Can't do it until near the end of the build because there wouldn't be room to remove and replace the board over and over again.