DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 21 Apr 2021, 06:50

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 131 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 14  Next
Author Message
PostPosted: 23 Sep 2009, 15:16 
Offline
Project Author
User avatar

Joined: 14 Oct 2008, 17:35
Posts: 906
Location: Dartmouth, Nova Scotia
The capacitor values will determine the frequency response range you will get at the output, the values I have would be the lowest ones I would use to get decent frequency response, Tim William only needed 0.02uF because he was using the preamp on an amplifier that didn't have very good frequency response because of the small transformer used. ;)

As for C2, I can't remember exactly its purpose either, not even sure if it does that much.

_________________
My Mini 12AU7 Tube Preamp, Pioneer SX-D7000, JVC XL-V221BK, JBL L80T, DCM TF700


Top
 Profile  
 
PostPosted: 06 Oct 2009, 06:05 
Offline

Joined: 06 Oct 2009, 05:45
Posts: 1
Hello. browsing I saw your project, the Mini 12AU7 Tube Preamp. I tried to build it but I not works.
I put a voltage of 100V and 12V for the tube. are two separate power supplies.
when I turn my own sound, and the music is dirty. Can you help me? thanks

my email. jolidj@hotmail.com.


Top
 Profile  
 
PostPosted: 06 Oct 2009, 16:49 
Offline

Joined: 06 Oct 2009, 16:37
Posts: 2
hello i am new to tube amps and i wont to make your mini 12AU7 for my guitar can you help ?


Top
 Profile  
 
PostPosted: 07 Oct 2009, 12:11 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4592
Location: Winnipeg, CANADA
Hi jolidj, can you post some photos and more details.

Hi jasoncpg, that preamp should work well as a guitar pre. What sort of help are you looking for?

Cheers, Gio

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 08 Oct 2009, 09:58 
Offline

Joined: 06 Oct 2009, 16:37
Posts: 2
hello the help i need is, a part list where is the best place to get the parts and is there a better amp to use with a mic? i am going to mic my harmonica - guitar but the amps r to much $ !


Top
 Profile  
 
PostPosted: 08 Oct 2009, 16:13 
Offline
Project Author
User avatar

Joined: 14 Oct 2008, 17:35
Posts: 906
Location: Dartmouth, Nova Scotia
Hello to both jolidj and jasoncpg, first of all to use a guitar you need to have the right input impedance, 1 meg ohm minimum, but I could not tell you what the preamp is set to at this moment but I think the guitar would work with it, or you could have a simple fet stage before the tube stage and use a tube stage with half of a 12AU7.

As for the parts list I would get a Hammond 162B12 or a 162D6 and the mini plastic case is also from Hammond, but I would recommend the slightly larger one that I got to build a "Mini" phono stage. The number is 1591CBK. All other components could be purchased at the Tube Depot, Parts connection, or can be salvaged from something, the tubes are nothing special.

As for the dirty sound problem, that could be numorous things. If you put too much input through the preamp it will distort really badly, a CD player has waaaay too much output for a preamp like this, it is meant for low level outputs that require lots of gain. :hot:

Email me some pics of the preamp if you can jolidj.

_________________
My Mini 12AU7 Tube Preamp, Pioneer SX-D7000, JVC XL-V221BK, JBL L80T, DCM TF700


Top
 Profile  
 
PostPosted: 10 Oct 2009, 13:29 
Offline
User avatar

Joined: 18 May 2009, 18:42
Posts: 22
Location: Littleton, Colorado
K so I build mine (well, everything sans the project box) and got it hooked up to my turntable. It actually sounds pretty decent, although like you said the low frequencies are a bit lacking (but i'm fine with just tweaking the equalizer on my big amp). There is one thing however, and that's a fairly low level hum behind the music. It sounds like it's at about 60Hz, so i feel like this hum is coming from the power supply. Is anyone else having this problem?


Top
 Profile  
 
PostPosted: 10 Oct 2009, 13:33 
Offline
User avatar

Joined: 18 May 2009, 18:42
Posts: 22
Location: Littleton, Colorado
Oh, and here's a pic (the power supply is disconnected, but i proceeded to play music through it all right after i took this)
http://img3.imageshack.us/img3/3143/img00079au.jpg


Top
 Profile  
 
PostPosted: 11 Oct 2009, 14:09 
Offline
Project Author
User avatar

Joined: 14 Oct 2008, 17:35
Posts: 906
Location: Dartmouth, Nova Scotia
I must say, that looks pretty creative. ;) Reusing a computer power supply case and you look to be using better quality components than what are in mine.

I am glad to hear that it works with a record player, this means that I could just make a version 2 design with an RIAA equalizer switch. I also have a recommended tube that should sound better than the 12AU7, the 6CG7 is basically a miniature 6SN7, and the only difference from the 12AU7 is that it has a 6.3V 600MA filament and pin 9 is not used. this is an easy change, you can put the filaments in series so that you can still use the 12V supply. :up:

As for the noise, this is usually a grounding problem, I have this problem with just about every project and it can be very tricky to get rid of in some cases. Also try a ground wire to the record player, this is often a problem, most record players have a ground wire that would normally hook up to the chassis, in this case connect it to the star ground or common ground.

_________________
My Mini 12AU7 Tube Preamp, Pioneer SX-D7000, JVC XL-V221BK, JBL L80T, DCM TF700


Top
 Profile  
 
PostPosted: 12 Oct 2009, 15:32 
Offline
User avatar

Joined: 18 May 2009, 18:42
Posts: 22
Location: Littleton, Colorado
Quote:
As for the noise, this is usually a grounding problem, I have this problem with just about every project and it can be very tricky to get rid of in some cases. Also try a ground wire to the record player, this is often a problem, most record players have a ground wire that would normally hook up to the chassis, in this case connect it to the star ground or common ground.


I do have like, every ground connected to one node. Are the low-voltage and high-voltage grounds supposed to be isolated from each other?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 131 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 14  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Google Adsense [Bot], Majestic-12 [Bot] and 18 guests


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 post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy