RCI-2980 Direct-Injected

This topic is for posting general questions and answers related to the info found in the High Fidelity Audio section above to KEEP THAT FORUM CLEAN! Only instructions, diagrams and schematics will be posted in the above section. PLEASE POST All YOUR QUESTIONS AND ANSWERS RELATED TO MODS SHOWN IN THE HIGH FIDELITY AUDIO SECTION HERE!
Post Reply
Woodbutcher637
WWPDX MEMBER
Posts: 14
Joined: Fri Apr 29, 2016 12:22 am

RCI-2980 Direct-Injected

Post by Woodbutcher637 »

Do the Goldfinger Tx mods have any affect if direct-injected?
User avatar
Goldfinger
Site Maintenance
Posts: 3849
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: RCI-2980 Direct-Injected

Post by Goldfinger »

No, the whole microphone amp chain is bypassed. As long as the blocking capacitor used at the injection point is of sufficient value (10uF), full bass will be passed on transmit.
wwpdx
wwpdx.com

Image
Woodbutcher637
WWPDX MEMBER
Posts: 14
Joined: Fri Apr 29, 2016 12:22 am

Re: RCI-2980 Direct-Injected

Post by Woodbutcher637 »

Thanks for such a quick response. I used a 10uf electrolytic, would changing it to a tantalum, or changing the value have any affect? I seem to have ALOT of bass.
User avatar
Goldfinger
Site Maintenance
Posts: 3849
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: RCI-2980 Direct-Injected

Post by Goldfinger »

If the values are the same, switching between Electrolytic/Tantalum/Mylar/Polypropylene, only changes tonal quality. The low frequency cutoff point will be the same. Each type of cap has it's own unique sound signature and that it why guys choose certain "types" of caps when designing speaker crossovers. Any of them will work fine but for hi-fi CB, I prefer Tantalum or Mylar and usually use Tantalum because of the small size.
I've found that 10uF is a good value because it allows response down to 20Hz. Many times in direct injected radios, the illusion of "too much" bass is actually because there is too much signal amplitude in the 80-250Hz region. That's why it's important to have an EQ inline that has at least 15 bands. I like to boost 30Hz - 6-8db, 60Hz - 3-5db, 120Hz flat, 250Hz - -2db, etc. In other words, only boost the ultra low bass and leave the mid-bass either flat or with a little cut. The male voice has plenty of amplitude between 125 and 500hz so no boost is usually needed in that range, Then you can add a small boost at 2K, a little more at 4K, etc to add some presence and highs for clarity. Once you get it set for your voice, you can leave it be.
wwpdx
wwpdx.com

Image
Woodbutcher637
WWPDX MEMBER
Posts: 14
Joined: Fri Apr 29, 2016 12:22 am

Re: RCI-2980 Direct-Injected

Post by Woodbutcher637 »

I just got these in the mail "400V 225J 2.2uF 400V 225 CBB capacitance 5% 20MM CBB Metallized Film Capacitor". I was wondering if these would be alright for the receive mod. I also got some tantalum 10uf and 2.2uf.
User avatar
Goldfinger
Site Maintenance
Posts: 3849
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: RCI-2980 Direct-Injected

Post by Goldfinger »

Yes, the film caps should sound great for the receive mod. They are probably kinda big size-wise but there is plenty of room in a 2980. I've used 250 volt mylars that were pretty big as well. There is no harm though as long as you can get them in there cleanly. :)
wwpdx
wwpdx.com

Image
Woodbutcher637
WWPDX MEMBER
Posts: 14
Joined: Fri Apr 29, 2016 12:22 am

Re: RCI-2980 Direct-Injected

Post by Woodbutcher637 »

Yes, lol these things are huge. I searched for these for awhile finding mostly only large quantities, or large shipping costs.
User avatar
Goldfinger
Site Maintenance
Posts: 3849
Joined: Sat Jun 30, 2007 12:27 am
Location: Beaver State

Re: RCI-2980 Direct-Injected

Post by Goldfinger »

Luckily there is lots of room under the board on base stations. It gives more mounting options when the parts side of the board is congested.
wwpdx
wwpdx.com

Image
Post Reply

Return to “>>> HIGH FIDELITY AUDIO Q and A <<< POST QUESTIONS AND COMMENTS HERE!”