electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software
Transistor choice in TR-808 voice clones -- 2N2222 vs BC547
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 1 of 1 [2 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
Hashtag Octothorpe



Joined: Jun 11, 2017
Posts: 57
Location: Grand Rapids MI

PostPosted: Wed Feb 14, 2018 10:45 am    Post subject: Transistor choice in TR-808 voice clones -- 2N2222 vs BC547 Reply with quote  Mark this post and the followings unread

I'm "card-boarding" (like a mix between breadboarding and point-to-point where components and power rails are on the top of the card and all the ground connections get poked through the card) voices for the TR-808, and the first version of the hat sounded *amazing* but it broke because I was inexperienced and my technique has improved, so I built a 2nd one.

It sounded **so much worse** -- very distorted and crackly. As though the 6-oscillator-metallic noise was clipping hard.

Last night when I was troubleshooting the cymbal, experiencing the same issue, it occured to me that maybe it's my transistors. My first three voices I used BC547s for the NPN transistors, and I switched to the 2N2222 simply because that's a really cool name, and also the orientation makes more sense to me in my brain with the flat side to the right in most schematics.

However, the specs aren't identical. The 2N2222 has more current output? In the "swing-type" VCAs in these voices, that's going to make a difference, right? I've tried different op amps (NE5532 vs TL07x) and types of capacitor, and neither of those things made any difference I could hear with my regular ears.

Oh, I *am* running off +/-12V and not +/-15, so I'm voltage-starving these circuits. But remember my first hi-hat sounded great.

Here's a video of a 4-pole high-pass VCF and at the end you can see the circuitboard in case you're wondering about my construction technique.
https://www.youtube.com/watch?v=Qf-mEcOW0nk
Back to top
View user's profile Send private message
Hashtag Octothorpe



Joined: Jun 11, 2017
Posts: 57
Location: Grand Rapids MI

PostPosted: Thu Feb 15, 2018 5:40 am    Post subject: Reply with quote  Mark this post and the followings unread

I swapped out the transistors in the audio path, which didn't change much. Putting a 1.5M resistor between the noise source and the first filter got the clipping under control. Now my hat sounds perfect! Next it'll be the cymbal.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: jksuperstar, Scott Stites, Uncle Krunkus
Page 1 of 1 [2 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use