Hybrid amplifier.. Please help.. - Page 10 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 2nd March 2006, 02:54 AM   #91
diyAudio Member
 
Join Date: Jun 2005
Location: Aberystwyth / Llanelli (wales)
Send a message via MSN to DoomPixie
Hi chris,
You are precisley right, i was just useing what i had here to prove the circuit before i spend any money on it..
There are a few things i have to order before i can do much more with it so i will throw some different output transistors into the order and have a little play and see what works best for me.
At the moment i'm just happy that it is finally working and that it sounds half decent, It is afterall my first dive into the realms of DIY solid state Audio.
I spose next thing i have to do is sort out the muteing relay to go between the tube and SS stages..
Would it be terribly wrong if i mounted the drivers ont he heatsink aswell and built it P2P on tag board? i was looking at it earlier and there are so few conponents that it would be easier to do this way and cut down on solder joints. the tube stage will be wired pretty much entirley ont he back of the tube sockets as there really isnt anythign there that even warrants tag board. Power supplies Both have their own PCB's anyway and these are already built. Or would i be better off just etchign a couple of small PCB's?
I spose the proper way to do it would be to make a PCB with the tube stage, the muteing circuit and the Output stage conponents all on one board.. and the board really wouldnt be that large if i did it this way so mabey i will do this, I'll have a play in eagle and see what i can come up with..
Many thanks,
Owen

  Reply With Quote
Old 2nd March 2006, 04:30 AM   #92
AAK is offline AAK  United States
diyAudio Member
 
Join Date: Jul 2004
Location: Florida
Hi Owens,

If you connect a relay between the tube section and the SS section you'll need a cap between the TS output and the relay. Without the cap when the relay kicks in, there could will be a voltage spike equal to the TS dc output voltage (assuming the voltage across the 2.2uF cap is zero) on the other end of the SS input 2.2uF caps at Q2 and Q4 that could damage the amp, and possibly your speakers if connected. I figured I'd bring it up just in case. It's why I suggested putting the relay at the output, instead of using an extra cap, plus the advantage of speaker protection. And as long as there is no output load the BJTs won't sweat it as the tube section stabilizes.

Cheers,

Al
__________________
Love when you can, Cry when you have to, be who you must, that's part of the plan.
  Reply With Quote
Old 2nd March 2006, 11:55 AM   #93
ilimzn is offline ilimzn  Croatia
diyAudio Member
 
Join Date: Feb 2005
Location: Zagreb
Actually, no, you don't need an extra cap, but you do need a relay with two contacts.
This is what you do: you put one end of each contact ontot he bases of the driver transistors. The other end you connect to ground). Use the normally closed contacts, so that they open when the relay is energized and the amp un-muted.
When the relay is in mute position, the input of the SS stage is grounded AFTER the capacitors, so they are alowed to charge up to the output voltage of the tube stage. At the same time, the SS stage bias current is zero, by virtue of both sides of the bias generator being shorted to ground, i.e. the bias generator is shorted (it won't mind).
When the relay switches over to operating condition, the 10uF cap across the bias circuit sharges up increasing bias to it's normal value (it will take a fraction of a second so no problem), while the twi input caps only change voltage slighthly to accomadate the bias change.
This will work just fine, but of course will not protect the speaker in case something blows up and you get DC at the output!

Oh yes - also, add clamping diodes on the output ('arrows' pointing from output to +rail, and from -rail to output). This also clamps the input voltage to slightly over the SS stage rails, even without a load, although with BJTs damage due to charging coupling input caps is unlikely, it is a cheap precaution, and also helps if the amp is ever muted suddenly while providing considerable output voltage.
  Reply With Quote
Old 2nd March 2006, 02:40 PM   #94
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Owen,
For now you can use terminal strips. Your next incarnation will be more complicated and so will use a PCB. Whatever works for you.

Hi ilimzn,
Thanks, that's what I would have said. I implement the signal relay by simply shorting the lines to ground. Powering up the relay releases the ground. Works like a champ. I also use diodes reverse biased from the supplies to ground. This protects against supply reversal in the event one fuse blows with a shorted output. It then limits that DC to one diode drop. Before the fuse blows, there would be an offset problem. A relay to connect the speakers would be my preferred method.

Yes, reverse biased diodes from the speaker output to the supplies should be a common feature. I do the same thing. In kind, with this hybrid, the same should be done on the input to the output stage.

-Chris
  Reply With Quote
Old 2nd March 2006, 02:47 PM   #95
diyAudio Member
 
Join Date: Jun 2005
Location: Aberystwyth / Llanelli (wales)
Send a message via MSN to DoomPixie
Hey guy's,
you mean just regular diode's, like 1n4007 or do i have to use some fancy diode?
Thanks,
Owen
  Reply With Quote
Old 2nd March 2006, 02:51 PM   #96
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Owen,
1N4148's (signal diodes, low capacitance) should work well for the input. 1N5408 (or lower voltage, 3A rectifier) for the speaker and supplies. You can try 1N4007's (1A) and they may be fine. Depends on the amount of energy trying to go where it shouldn't. This one, 1A will be fine thinking about it.

-Chris
  Reply With Quote
Old 2nd March 2006, 02:54 PM   #97
diyAudio Member
 
Join Date: Jun 2005
Location: Aberystwyth / Llanelli (wales)
Send a message via MSN to DoomPixie
thanks chris, i'll have a dig around and see what i can find, i should have a box of diodes..somewhere... urmm.. probably under my bed i really should sort all my components out so their in one place..lol.
Owen
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hybrid amplifier A2 class Jaime Tubes / Valves 16 20th June 2012 10:39 PM
The Hybrid Class A amplifier gaborbela Tubes / Valves 135 24th May 2012 05:33 PM
amplifier for hybrid car? star882 Car Audio 8 24th May 2009 04:50 AM
The Perfect Hybrid Amplifier Stee Solid State 0 27th July 2008 08:03 PM
Hybrid amplifier help... DoomPixie Tubes / Valves 83 20th February 2006 01:28 PM


New To Site? Need Help?

All times are GMT. The time now is 02:15 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2