Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Tom-s on May 05, 2016, 09:25:43 AM

Title: Altered soundstage with FAQ #3?
Post by: Tom-s on May 05, 2016, 09:25:43 AM

Anybody else experienced a smaller soundstage with the FAQ #3 implemented in crack?
Or can't this be the reason?

Title: Re: Altered soundstage with FAQ #3?
Post by: Doc B. on May 05, 2016, 09:28:15 AM

Changing the input impedance could change the tonal balance a little. That is what is usually happening when people say the soundstage is changing.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 07, 2016, 09:25:36 AM

Ok, thanks.
I thought it would have more to do with the extra resistor in the signal pathway vs the changed impedance.
When i find the time i'll remove it again.

Title: Re: Altered soundstage with FAQ #3?
Post by: Paul Birkeland on May 08, 2016, 08:04:33 AM

I would check your solder joints on the modification, just to be sure a flaky joint isn't causing the issue.  The input impedance remains roughly the same with the modification, so this shouldn't be a factor.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 08, 2016, 09:54:12 AM

I do a pinprick test on every new solder joint in the signal pathway. That showed no signs of a bad joint.
Might be my mind playing tricks on me. I'll remove it in 2-3 weeks time and see if i hear a difference.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 12, 2016, 11:26:57 AM

Different question.
A preamp makes the volume pot on crack sort of useless.
Would a 100K high quality resistor (Kiwame?) between the right RCA and A7, and another between the left RCA and A2 do aswel? The preamp is digital so a lower input impedance would work i think (10K).
In search of better audio quality :).
Opinions please?

Title: Re: Altered soundstage with FAQ #3?
Post by: Paul Birkeland on May 16, 2016, 06:36:54 AM

Turning the pot up all the way is equivalent to removing the pot and installing a pair of 100K resistors.  There isn't anything to be gained by going any lower than 100K with this value.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 18, 2016, 11:16:21 AM

I've got absolutely no technical background. Please confirm i've got the placement of these resistors correct in my earlier post.

Title: Re: Altered soundstage with FAQ #3?
Post by: Doc B. on May 18, 2016, 12:14:22 PM

I can confirm that you do not have it correct. The input load resistors do not go in series with the signal. They shunt from signal hot to ground. Connect a 100K resistor from the center pin of each RCA jack to the ground lug of that RCA jack. Then run a wire from the RCA center pin straight to the corresponding grid pin (A2 and A7 as you have suggested). This will be equivalent to turning the pot up all the way.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 19, 2016, 03:22:46 AM

Thanks to confirm this Doc. By looking at the schematic i figured i was wrong before. I'll do it as you suggested.

Title: Re: Altered soundstage with FAQ #3?
Post by: Tom-s on May 19, 2016, 10:11:18 AM

Works out perfectly! Thanks!