Help needed to find these rare values! - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 August 2004, 09:11 AM   #21
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
Hey, I really wannna know the amp's approx. power dissipation.

Is it really a big secret to tell?

And I don't think I'm gonna use the regulator. It'll probably just add complication to this dead simple SE amp

Quote:
Then there's the PS to consider also...
Yep...
Can you suggest me a PS for these amps...

I've got these things that could be used for it:

*1pcs 488VCT @70mA / 6.3V @6.2A, 64VA Potted Chicago Tranny

*12pcs 100ohm 50W Aluminium Clad Dale resistors

*Many EZ80/81 rectifiers (Inc. TFK).

*A few 5U4 and 1pcs GZ34, but wanna use'em for my next "BIGGIE" projects.

I haven't got any choke & cap yet...
I prefer not to use any choke for these amps, in order to keep things simple.

I'll buy caps later on, after the design is determined.

Oh yeah, I want to share single PS for both channels.


Cheers,
JayJay

PS: Man, sheep's eye dissection is just disgusting!!
But it was interesting though...
Did it on Friday for school biology practical work
  Reply With Quote
Old 2nd August 2004, 04:53 AM   #22
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
...
  Reply With Quote
Old 2nd August 2004, 11:13 AM   #23
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
Would it be OK to use EZ80, rather than EZ81?

I've got more of EZ80 than EZ81, but datas show that EZ81 can handle more.....
  Reply With Quote
Old 3rd August 2004, 09:39 AM   #24
MIKET is offline MIKET  United States
diyAudio Member
 
MIKET's Avatar
 
Join Date: Jul 2003
Location: Maine
Send a message via Yahoo to MIKET
Default Power Supply Design

Here is the Spec Sheet for the EZ80
http://tdsl.duncanamps.com/pdf/ez80.pdf
If you use 1 EZ80 per channel you should be OK
From the output of the rectifier place (Qty-2) 100 ohm resistors in series and a 50uF cap rated at least 330V. That should give you aprox. the 250VDC you desire. You have adiquate filiment current to handle all the tubes with the transormer you have on hand.
  Reply With Quote
Old 10th September 2004, 02:11 AM   #25
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
Hi,

Is it OK to use 60uF with EZ80

The maximum reservoir capacitance specified on my mullard data book is 50uF for EZ80, as well as EZ81...

I'm going to use Telefunken tubes...
  Reply With Quote
Old 10th September 2004, 02:37 AM   #26
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
Is it OK to use 60uF with EZ80
Provided you stay well below Iout_max at all times it should be O.K.

IMO it is however not the wisest thing to do as chokes are commonly available and those larghish cap values are really unnecessary for building a well filtered P.S.

Quote:
The maximum reservoir capacitance specified on my mullard data book is 50uF for EZ80, as well as EZ81...
True but look at Iout_max for both types so look at what your requirements are in that department: the EZ81 is the tougher cookie of the two.

Cheers,
__________________
Frank
  Reply With Quote
Old 10th September 2004, 06:25 AM   #27
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
Hey, can I make a summary here now....
Just to make sure that everything is correct for safety.


Power Output of each channel will be 4.2W

My transformer's HV secondary is 488VCT @ 70mA, single transformer used for both channels.

Two EZ80s are used, one for each channel.

Just for one channel:

EZ80 will be connected in fullwave rectification.

Straight after being rectified by the EZ80, one 100ohms (50W) power resistor is connected in series (is 100ohm enough?)

After the resistor connected in series, a 60uF 370VAC MKP cap is connected in parallel.

Overall, it's a Fullwave, RC filtered PS.



The transformer also has a 6.3V winding @ 6.2A, supplying 2X E80F and 2X EL84.

Is everything correct?

Cheers,
JayJay

PS: I don't want to use any choke for this amp... I just wanna make everything simple.

I'll use chokes for bigger projects coming up.
  Reply With Quote
Old 11th September 2004, 02:16 AM   #28
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
one 100ohms (50W) power resistor is connected in series (is 100ohm enough?)
Haven't read the thread from start to finish but if that 100R is the sole resistor in a Pi filter it's rather too low in value to be really effective. Go for something like 470R if you can spare the voltage drop.

Then, 50W? What for?
It's a SE amp so I'm sure 10W should do nicely already for a PS shared between channels.

Cheers,

EDIT: Just went back to post #1...Since your amp is basically the same as the fourth SE EL84 amp on Bonavolta's site why not take a peak at the PS used for that one?
Even if you'd go for a FW restifier scheme, current draw would be very similar anyways.
__________________
Frank
  Reply With Quote
Old 11th September 2004, 06:29 AM   #29
diyAudio Member
 
jamesjung21's Avatar
 
Join Date: Dec 2003
Location: New Zealand
Quote:
Since your amp is basically the same as the fourth SE EL84 amp on Bonavolta's site why not take a peak at the PS used for that one?
Well,

I'm still not familiar with valve amps, so here's a question:

As you know, in class-A SS, power supplied by PS sould be at least 4X the actual output power. i.e. 20W amp with 80W-100W supply.

What about in SE tube amps? The same?
If so, the PS suggested on the 4th of Bonavolta's site with my transformer(488VCT @ 70mA) will deliver less than twice the output power of 4.2W.

Cheers,
JayJay
  Reply With Quote
Old 11th September 2004, 01:10 PM   #30
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
If so, the PS suggested on the 4th of Bonavolta's site with my transformer(488VCT @ 70mA) will deliver less than twice the output power of 4.2W.
If you're using one xformer for both channels you'll end up short on voltage and current.
In case you have a pair of them you can still arrive at the operating voltages required by using a hybrid rectifier.
Don't forget that SE amps inevitably run in Class A.

IMHO it would be eaiser for you to choose a diagram and copy that than working from a powerxformer and figuring out what you can do with it. Just my opinion though...

Cheers,
__________________
Frank
  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
*rare*brand New Avalanche 18 Brand New *rare* thadman Swap Meet 2 17th September 2007 04:20 PM
Info needed on this very rare Kenwood deck Kuja Analogue Source 0 29th September 2006 02:19 PM
Help needed to find PVM 1702 Alexiss Digital Source 9 19th August 2006 08:03 PM
Help desperately needed with find TomJ Solid State 3 2nd May 2003 08:24 PM
Cant find capacitor values - help purist Multi-Way 4 29th April 2003 07:50 PM


New To Site? Need Help?

All times are GMT. The time now is 08:58 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