Hafler DH-200/220 Mods - Page 91 - 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 23rd July 2010, 02:47 AM   #901
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by Jacques Merde View Post
It might be easier to get an isolation transformer which will step the mains voltage down to 110.
Or even, as isolation isn't required, a variac. Out shopping recently I was surprised how cheap a 1kVA variac was. Cased up, it listed a bit lower than what I paid for a custom 1kVA toroidal.
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 23rd July 2010, 02:53 AM   #902
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by scott wurcer View Post
I thought there is a dual winding transformer that simply requires the change of a couple of jumpers.
The man. shows two possible transformer types - the 'domestic' (T401) and 'international' (T402). If the OP has the domestic US variant, it has a single primary.
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 23rd July 2010, 02:54 AM   #903
alexg is offline alexg  Philippines
diyAudio Member
 
alexg's Avatar
 
Join Date: Jan 2005
Location: Philippines
Quote:
Originally Posted by Jacques Merde View Post
Other than the mains voltage, is there another reason you want to replace the EI transformer with a toroidal? It might be easier to get an isolation transformer which will step the mains voltage down to 110.
Actually, the price of the toroidal and the price of a decent step down (1KVA) is almost the same locally.

So, am more inclined to replace the transformer to avoid clutter.

Another option that I am thinking is having the EI transformer, re-wound for 220VAC primary. Labor in our country is so inexpensive.

Am trying to avoid having a 110V audio equipment, am a klutz and I might plug it on my mains outlet and burn the Hafler.

Last edited by alexg; 23rd July 2010 at 02:57 AM.
  Reply With Quote
Old 23rd July 2010, 02:57 AM   #904
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by alexg View Post
Another option that I am thinking is having the EI transformer, re-wound for 220VAC primary. Labor in our country is so inexpensive.
Copper's not though so hopefully you'll get scrap value back on the 120V windings (which will be thicker wire as fewer turns).
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 23rd July 2010, 03:26 AM   #905
alexg is offline alexg  Philippines
diyAudio Member
 
alexg's Avatar
 
Join Date: Jan 2005
Location: Philippines
Quote:
Originally Posted by abraxalito View Post
Copper's not though so hopefully you'll get scrap value back on the 120V windings (which will be thicker wire as fewer turns).
Actually, copper is not that expensive, the core is more expensive.

I just talked to a friend who owns a transformer factory, he will wind for me and just give me the bobbin with the windings, I will try to recover the core from the original transformer and stack it myself to the new bobbin...
  Reply With Quote
Old 23rd July 2010, 03:58 AM   #906
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by alexg View Post
Actually, copper is not that expensive, the core is more expensive.
It certainly seems relatively expensive here, when I bought a 100m reel of wire it was more than lunches for a week.

Quote:
I just talked to a friend who owns a transformer factory, he will wind for me and just give me the bobbin with the windings, I will try to recover the core from the original transformer and stack it myself to the new bobbin...
Sounds like a fun exercise. I still remember the old days when RS sold transformer kits for building your own EI. Only had to wind the secondary though - doing your own primary is more challenging I think. Stacking the laminations and not getting any rattles or hum may be an even bigger one...
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 25th July 2010, 02:26 AM   #907
alexg is offline alexg  Philippines
diyAudio Member
 
alexg's Avatar
 
Join Date: Jan 2005
Location: Philippines
I just replaced the 4 100uf electrolytics on the driver board with 4 220uf Panasonics (I have on hand used for bypassing tube projects, the Hafler is my first SS project). Sound is pretty much imporoved.

The board have a 470uf bi-polar cap, I cannot find better replacements, how low of a capacitance can I go? I have a bunch of polypropylene and polyester caps, the highest is 20uf... I wonder if I can use these instead.

Thanks.
  Reply With Quote
Old 25th July 2010, 10:22 AM   #908
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by alexg View Post
... I wonder if I can use these instead.
You certainly can, but bass performance will suffer. This cap determines the low frequency roll-off of the amp. Reducing it by a factor of 20 sounds rather drastic... But try it and see what it sounds like. You could try substituting back-to-back 1000uF polarised electrolytics if you don't like the sound of your 20uF.
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 26th July 2010, 09:31 AM   #909
alexg is offline alexg  Philippines
diyAudio Member
 
alexg's Avatar
 
Join Date: Jan 2005
Location: Philippines
Quote:
Originally Posted by abraxalito View Post
You certainly can, but bass performance will suffer. This cap determines the low frequency roll-off of the amp. Reducing it by a factor of 20 sounds rather drastic... But try it and see what it sounds like. You could try substituting back-to-back 1000uF polarised electrolytics if you don't like the sound of your 20uF.
Back to back, does it mean, - connected to the -?

I asked if I can lower it because in vacuum tube circuits, hardly I would go beyond 2.2uf for an output cap.

Thanks.
  Reply With Quote
Old 26th July 2010, 09:57 AM   #910
djk is online now djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"hardly I would go beyond 2.2uf for an output cap."

Calculate the RC corner.

The R is 150 ohms. 20F would then be 53hz.
__________________
Candidates for the Darwin Award should not read this author.
  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
Hafler dh110 mods anyone? amp_guy Solid State 5 30th January 2011 01:57 AM
Hafler xl-280 mods Audionirvana Solid State 5 11th November 2010 05:25 AM
Hafler DH 101 preamp mods Zen Mod Solid State 6 3rd May 2004 01:24 AM


New To Site? Need Help?

All times are GMT. The time now is 11:41 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