Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Transistor Preamp
Transistor Preamp
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st September 2016, 07:43 AM   #1
Jrp27 is offline Jrp27  India
diyAudio Member
 
Join Date: Apr 2016
Default Transistor Preamp

Any good small, easy, high fidelity transistorised preamplifier circuit that i can build ? Plan to use it with my DIY power amp. The preamp should be able to accept ipod level input.

Any help would be appreciated.
  Reply With Quote
Old 1st September 2016, 08:55 AM   #2
Richidoo is offline Richidoo  United States
diyAudio Member
 
Join Date: Oct 2005
Location: Raleigh
iPod 5G makes 1V output level. What is the input voltage that drives your DIY amp to full power? You probably only need 6dB voltage gain (2x.)

An opamp with 10k resistor in feedback loop will give you the +6dB gain, and is adequate performance for iPod source quality. I like ST Micro MC33079 dual opamp.

Something like this from Rod Elliott:
Transistor Preamp


Also, see his full page of preamp circuits, some are discreet (not opamp)
ESP Projects Pages - DIY Audio and Electronics
  Reply With Quote
Old 1st September 2016, 09:40 AM   #3
Nikolai Petrenko is offline Nikolai Petrenko  Viet Nam
diyAudio Member
 
Join Date: May 2016
Location: Hanoi
Quote:
Originally Posted by Jrp27 View Post
Any good small, easy, high fidelity transistorised preamplifier circuit that i can build ? Plan to use it with my DIY power amp. The preamp should be able to accept ipod level input.

Any help would be appreciated.
Try Rod Elliott P37A, may be not as good as OPA2132, but at least you should try once in your life
An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

You shouldn't use capacitors in the output if you can trim the VR1L to set output as close to 0V as you can or the following stages already have AC coupling caps. If must use, you should use film or paper or PIO cap like WIMA MKP10 (2x 10uF in parallel) or Mcap or K40U.... Avoid bipolar capacitors since they are not good if long-term stable is required.
  Reply With Quote
Old 1st September 2016, 10:50 AM   #4
franzm is offline franzm
diyAudio Member
 
Join Date: Dec 2010
For ipod and other devices with headphone output on can use step-up transformers.
  Reply With Quote
Old 1st September 2016, 12:26 PM   #5
Nikolai Petrenko is offline Nikolai Petrenko  Viet Nam
diyAudio Member
 
Join Date: May 2016
Location: Hanoi
Quote:
Originally Posted by franzm View Post
For ipod and other devices with headphone output on can use step-up transformers.
High fidelity coupling transformer are expensive and clumsy, especially in stereo mode, if two transformers are placed close together as result of space problem, cross-talk will appear because magnetic field of one transformer will affect the other.
Cheap or medium transformers will sound like crap! Distortion and weak of very low AF.
I think solid-state preamp will be the best choice for: money, space and sound performance.
  Reply With Quote
Old 1st September 2016, 04:06 PM   #6
Struth is offline Struth  Canada
Banned
 
Join Date: Aug 2012
Location: books at londonpower.com
Hi Guys

I know there are different file formats that one CAN use, but who using an ipod will use the highest fidelity format? The source fideltiy is already low, so no circuit suggested is likely to impair the sound.

What circuit is the PA? Is it a chip amp? Any opamp preamp will provide performance better than the ipod output quality. The circuit in post-2 should have a cap in series with the resistor to ground in the feedback loop. This will assure minimum output DC offset. otherwise, there could be a tiny DC voltage at the output that could upset the PA input.

NEVER use paper dielectric capacitors. They dry out over time and change their characteristics and cause high signal loss. A customer brought me an old amp that had very low output. I replaced the paper coupling caps with modern plastic types and the amp had its full power again. So, actually i stand corrected by myself: paper capacitors will impair the sound of even an ipod.

Digital audio can sound quite amazing but no such system I've ever heard used an ipod.

Have fun
  Reply With Quote
Old 1st September 2016, 04:22 PM   #7
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Transistor Preamp
I like Apex designs - they are easy to make, work, and sound good.

BJT:
Click the image to open in full size.

FET:
Click the image to open in full size.

Click the image to open in full size.

More here:
100W Ultimate Fidelity Amplifier
  Reply With Quote
Old 1st September 2016, 07:11 PM   #8
Project16 is offline Project16  France
diyAudio Member
 
Project16's Avatar
 
Join Date: Nov 2012
Location: Cognac
Quote:
Originally Posted by xrk971 View Post
I like Apex designs - they are easy to make, work, and sound good.

Click the image to open in full size.
Hello xrk971
I like your work, the files (.pdf or gerber) are available?

Regard's.
  Reply With Quote
Old 1st September 2016, 07:27 PM   #9
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Transistor Preamp
That is Apex Audio's work - I just re-posted. I asked him in his thread if pcb files are available. He will let us know if he has pcb files. I am looking for a good preamp as well.

100W Ultimate Fidelity Amplifier
  Reply With Quote
Old 1st September 2016, 07:46 PM   #10
Project16 is offline Project16  France
diyAudio Member
 
Project16's Avatar
 
Join Date: Nov 2012
Location: Cognac
Thank you for the reply and congratulations for the good work of amplifiers achievements proposed on the forum.
  Reply With Quote

Reply


Transistor PreampHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Transistor mic preamp pps2086 Analog Line Level 19 3rd March 2016 06:24 AM
Transistor Preamp Design for ADC ksubieta Analog Line Level 6 21st October 2012 01:26 AM
Lm386 Preamp Transistor ? prorms Chip Amps 2 22nd May 2006 06:00 PM


New To Site? Need Help?

All times are GMT. The time now is 04:16 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki