• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Matisse Fantasy waveform output test

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If your budget is only HK$2K, seems Hammond 1627 is the choice.

The primary impedance of OPT for 300B should be within 2.5 to 3.5K.

I don't know much about the Chinese made OPT's except the James transformer from Taiwan seems to be quite good indeed.

Is your name Wong Chi Kwong? He is my classmate in HK Poly.

JOhnny
 
Hammond's distributor in HKG

I check Hammond's web site. Here is their distributor in HKG.

Farnell-Newark InOne
Registered Office
Unit B, 12th Floor, Entertainment Building
30 Queen's Road Central
HONG KONG

Tel: 800 968 280 or +65 788 0200
Fax: 800 968 480 or +65 788 0300
www.farnellinone.com


By the way, the phone/fax numbers seems a bit strange to me. Of course, you can easily find their phone number from phone book.

JOhnny
 
Hammond transformer

Hi CK,

You may check Hammond's web site to choose their power transfomer, and choke as well. They are very good too.

My friend and myself built several 2A3 power amplifer with Hammond's irons. We found them they are with very good quality.

If you need some help in picking the type of power transformer and choke, please let me know.


Johnny
 
Thank you so much your help.

I can't find the product from HK Farnell.

But I will check the price to theml. I know some of their stuffs pricing is double to my seeing at MonKok Maks. I have their products catalog, so this OPT I can compare with the price to the other reseller of US . Like a mouser or Digi-Key ...

Power transformer I already have one bought from Taiwan's my3c.net , the model is T330 follow the link look at this "http://www.my3c.net/product/detail.asp?gid=0&ky=t330&pid=1691"

Are you sure I should deploy a Chock ? I have seen some of designs without it and instead to use solid state acting on it. I want to know two kind of difference based on sound level reproduction.

You say 2A3 , is it a substitution of 300B ?

CK
 
This is about right for the price and delivery lead time.

They don't have the OPT's in stock. They have to order them directly from Hammond and shipped from Canada or USA.

Well, 10 weeks isn't too long. Make up your mind. It's better to order the power transformer and choke as well.


Johnny
 
Chinese made OPT

Check at VT4C's web site. They offer various output transfomer. I don't know the quality but the price is very attractive:-

http://www.vt4c.com/shop/program/main.php?cat_id=30&group_id=7&hit_cat=

LM-9911U
3.5k output transformer designed for 845/300B SE.


3.5k Single Ended Output for 300B or low votlage 845

Max 120mA

Large 150W core enough 40W Class A power output

Made in China

Weight :2750 (gram/Each)
Size (mm): 92 x 82 x 99H
Power: 40 Watt


Item No: LM-9911U
Quantity (Each) Price (US$)
1 - 3 72.00
4 - 9 65.00
10 or more Call
 
47K of 12AT7's Grid resistor is a wrong value because it makes to the resultant loading resistor of the previous stage (12AX7) to become around 47K, which is an unacceptable loading (even lower than the plate resistance of 12AX7). You may get an unsymmetrical sine wave or very hign distortion.

470K is a reasonable value.
 
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