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

Solid State Talk all about solid state amplification.

Krell KSA 100mkII Clone
Krell KSA 100mkII Clone
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 7th March 2008, 07:44 PM   #2101
dung0981 is offline dung0981  United States
diyAudio Member
 
Join Date: Apr 2006
Location: CA
Quote:
Originally posted by stolbovoy
No it is from Toroid of Maryland (toroid.com). John told me that his machines can't do required wire bifillar (too thick).

Cost without shipping is 2 posts on top
$316.06 if 2-4 pcs ordered
$230.60 if 5-9 pcs
$198.82 if 10 or more ordered
(without tax and shipping )

What about driver stage? I think we can save some money when we order the driver tranny also.
  Reply With Quote
Old 7th March 2008, 08:04 PM   #2102
stolbovoy is offline stolbovoy  United States
diyAudio Member
 
Join Date: Jul 2004
Location: MD, USA
I'm trying to find "of the shelf" separate EI transformers for that
  Reply With Quote
Old 7th March 2008, 09:26 PM   #2103
RKH is offline RKH  United States
diyAudio Member
 
Join Date: Sep 2002
Location: Colorado, USA
Apologies for not seeing the post a screen or so up (on my machine)

Ryan
__________________
Lighten up while you still can ...
  Reply With Quote
Old 8th March 2008, 05:35 PM   #2104
Flodstroem is offline Flodstroem  Norway
diyAudio Member
 
Join Date: Sep 2004
Location: Norway
Quote:
Originally posted by stolbovoy
I'm trying to find "of the shelf" separate EI transformers for that
Please dont do that.
Before ordering the mains transformer read listed posts carefully:
#1836
#1844
#1845
#1851
#1852

Maybe you will find some beneficial inputs before you finally decide how the mains transformer should look like. Im very concerned about the mains voltage
capability, it should be 110, 115, 120V x 2 for to suit worldwide mains voltage from 110V to 240V (e.g. 110,115, 120, 220, 230 and 240 mains voltage)

Also if implementing the 12v windings there will be an option for soft start and a relay-drive for different protection circuits (not any more expensive than for an extra small transformer including fuses, printed circuit boards etc....

Then............I might be interested in 6-8 transformers depending on price level (also there is some interests in Denmark too I know.)

Regards
__________________
Regards
Flodstroem
  Reply With Quote
Old 8th March 2008, 08:39 PM   #2105
stolbovoy is offline stolbovoy  United States
diyAudio Member
 
Join Date: Jul 2004
Location: MD, USA
Quote:
Originally posted by Flodstroem


Please dont do that.
Before ordering the mains transformer read listed posts carefully:
#1836
#1844
#1845
#1851
#1852

Maybe you will find some beneficial inputs before you finally decide how the mains transformer should look like. Im very concerned about the mains voltage
capability, it should be 110, 115, 120V x 2 for to suit worldwide mains voltage from 110V to 240V (e.g. 110,115, 120, 220, 230 and 240 mains voltage)

Also if implementing the 12v windings there will be an option for soft start and a relay-drive for different protection circuits (not any more expensive than for an extra small transformer including fuses, printed circuit boards etc....

Then............I might be interested in 6-8 transformers depending on price level (also there is some interests in Denmark too I know.)

Regards
The specs from toroid.com has dual 120V primaries, so it should be fine for both Europe and US. If 47V vs 52 on 220 and 110 mains is big concern for someone who is willing to join, I can ask to make a tap for 110V.

What's wrong with using separate EI transformer[s] for anything else, except output stages? Hammond ones cost about $20 at mouser.com.
  Reply With Quote
Old 8th March 2008, 10:50 PM   #2106
Flodstroem is offline Flodstroem  Norway
diyAudio Member
 
Join Date: Sep 2004
Location: Norway
In Europe the mains voltage are 220, 230 and 240V just for your information
This could change the DC-rails by as much as 4-5 volt up and raise the idle dissipation by 23-24Watts.

A word about an extra EI-transformer: If you would like to put in some noisy magnetic leaking EI transformer in your chassis, go a head, but then I dont get this: you are going to order an electric and magnetic screened totoidal transformer for to receive a silent, noise-free amp and then you are going to put in some of the worse type of.....
Hmmmm I dont understand it.

Dont you think there is a benefit to choose an extra windings on the mains transformer instead of that $ 20 simple transformer and you do forget that it will need the mains fuses too including space to mount it at (far away from the PCB and input circuits for to avoid picking up hum and noice. This isnt cheap I can tell you (you also forgot to add the shipping costs, custom tax etc..) and you have to calculate more bucks for this than those $ 20 you count for, this is my experience.

Better up for to add some more windings on mains transformer dont you think?

Have you checked the price picture for to add windings? The magnetic wire will be thin (0.5Amps? and would be negligible, you mostly pay for work I guess.

Regards
__________________
Regards
Flodstroem
  Reply With Quote
Old 9th March 2008, 03:23 PM   #2107
stolbovoy is offline stolbovoy  United States
diyAudio Member
 
Join Date: Jul 2004
Location: MD, USA
Quote:
Originally posted by Flodstroem
In Europe the mains voltage are 220, 230 and 240V just for your information
This could change the DC-rails by as much as 4-5 volt up and raise the idle dissipation by 23-24Watts.
Using 240V primaries for 220V mains will actually lower idle dissipation, but because everything except output stage will be fed from stabilized PS, it should not affect clipping. Anyway we should first figure out is there any people from Europe which are interested in buying the transformer from US (pay extra for shipping, customs, etc) if it will fit their needs

Quote:
A word about an extra EI-transformer: If you would like to put in some noisy magnetic leaking EI transformer in your chassis, go a head, but then I dont get this: you are going to order an electric and magnetic screened totoidal transformer for to receive a silent, noise-free amp and then you are going to put in some of the worse type of.....
Hmmmm I dont understand it.

Dont you think there is a benefit to choose an extra windings on the mains transformer instead of that $ 20 simple transformer and you do forget that it will need the mains fuses too including space to mount it at (far away from the PCB and input circuits for to avoid picking up hum and noice. This isnt cheap I can tell you (you also forgot to add the shipping costs, custom tax etc..) and you have to calculate more bucks for this than those $ 20 you count for, this is my experience.

Better up for to add some more windings on mains transformer dont you think?

Have you checked the price picture for to add windings? The magnetic wire will be thin (0.5Amps? and would be negligible, you mostly pay for work I guess.
Flodstroem, thanks for valuable comments. You are right, I'll quote on Tuesday:
Option A: additional 2*65V*1A and 2*12V*0.5A (for protection and soft start)windings
Option B: additional 2*27V*1A (to add "on top" of 2x38V*12A) and 2*15V*0.5A (for protection and soft start) windings

I'm not sure that we need option A, because 38V*12A windings will be coupled pretty well with 2*60V*0.7A anyway
Is 65Vac enough to build decent stabilized PSU with 55-56V output and use RC filtering, or should be go for something higher?
  Reply With Quote
Old 9th March 2008, 04:41 PM   #2108
stolbovoy is offline stolbovoy  United States
diyAudio Member
 
Join Date: Jul 2004
Location: MD, USA
Quote:
Originally posted by stolbovoy
I'm not sure that we need option A, because 38V*12A windings will be coupled pretty well with 2*60V*0.7A anyway
Option A can be actually used for better ground layout (to separate low level and power ground)
  Reply With Quote
Old 9th March 2008, 05:44 PM   #2109
stolbovoy is offline stolbovoy  United States
diyAudio Member
 
Join Date: Jul 2004
Location: MD, USA
Quote:
Originally posted by stolbovoy
Option A: additional 2*65V*1A and 2*12V*0.5A (for protection and soft start)windings
Correction: 2*15V*0.25A for protection, soft start and etc
2*65V*0.7A for main board.
I don't think it will affect prices much.

If interested, please specify primary voltage you need. I plan to ask for final quotes Tuesday.
  Reply With Quote
Old 9th March 2008, 07:35 PM   #2110
Flodstroem is offline Flodstroem  Norway
diyAudio Member
 
Join Date: Sep 2004
Location: Norway
I think option "A" sound most interesting and I cant see any reason for it to be more expensive than option "B".

Both models from KRELL, the KSA-80 and KMA-160 had 39V and 75V DC regulated power supplies for the LTP and driver stage and if using this as a starting point we could think of a DC drive between 39V + 65-75V depending on application or personal solution in the KSA-100 mkII project.

Regarding the 2 x 65V winding Im wandering if this is to high voltage, 65 x √2=92V-2volt=90V DC over filter caps and if regulated to 65-75V DC there will be plenty of Voltage for the purpose, but heat dissipation could be a problem due to high voltage and perhaps 0,3 to 0,4A idle currents thru drivers. 90-65=25V and heat dissipation would be approx. 25V x 0,4A = 10W and a totals of 20W worse case, both rails.

For to get 75V regulated voltage at 50 Hz mains freq. the DC voltage over filter caps should be at least 10% more than output = 82,5 volt after rectifier, add 2 volt for that rectifier and you will end up with 84.5/√2=approx. 60V AC, exactly the same AC as in the KSA-80 and KMA-160.

Regarding primaries it could be: 0V-110V-120V x 2 then we should have an option for the must common mains voltage (110, 120, 220, 230 and 240V) but for those in the US that have the 115 V could choose to wire the transformer for either 110 V (higher power outputs (approx. 4.5%) or wire it for 120V and get less heat dissipation and less power output (approx. 4%).

So If you agree to it:
option "A" I would like to suggest to be 2 x 60 V AC @ 0,7-0,8A and 2 x 15V AC for protection circuits etc.

You should also rise the 38 V windings to be 39V to be more equal to Krell original transformer (at no extra costs)

If keeping those 10V, 12A windings this could be useful to those who wants to build a 200+ watts version of the KSA-100 (KMA-160 or similar, 39+10V=49V AC), or to those that is in the need of a power transformer for the KSA-50 project (39-10V= 29V AC)

Mains voltage: (0V-110V-120V) x 2

This solution must be considered due to interests of the members of this tread (and the KSA-50 tread) and if a low interest this transformer will be expensive I think but you should do a search for interested builders.

Or consider a GB.

Regards
__________________
Regards
Flodstroem
  Reply With Quote

Reply


Krell KSA 100mkII CloneHide 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


New To Site? Need Help?

All times are GMT. The time now is 07:16 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki