Output Transformers for WE-437a WOT Line Preamp

snoopyma · 23rd January 2005, 09:30 AM

I want to upgrade the output transformers for my WE-437a WOT line preamp. Some details of my preamp are:
WE-437a tubes;
Output transformers of EI cores;
Volume control using S&B TVC;
Power supply using tube rectified with choke and regulated with Allen Wright's Super-regulator board;
Voltage = 195 volt, Current = 25ma;
XLR input and output.

In this upgrade, I prefer double-C cores. After some internet searching, some possible canditiates are Lundahl LL1689 or LL1660, Bartulloci Model C or Model E. Would anyone suggest which is the best for my case? Or any other counterparts? And the prices?

Please also advise what's the difference in terms of specification and sonic quality if the laminations of the cores are thinner.

The speakers that I am using are 4-way horn speaker system with 15" woofer. I want dynamic and speedy sound with wide frequency response. Any information and advice is greatly appreciated. Thanks in advance.

analog_sa · 23rd January 2005, 11:01 AM

I have used LL1660 18mA 4.5:1 in a similar setup. I find it very nice for the money.

Have you considered replacing the transformer with a choke and parafeeding the S&B?

Jaap · 23rd January 2005, 11:44 AM

http://www.headwize.com/projects/sho...ciuff4_prj.htm

If you lower the current to 20 mA you can use the LL1630/10 mA.
I am using this as a pre-amp and it is superb. You can also try the 5842 and 6H30 tubes with this design. some experts say that less current gives better sound.

I have some unused 1630's for sale but that's not the reason I give you this advice

snoopyma · 28th January 2005, 02:31 PM

Thank you for the replies. I'm interested in trying the parafeed my preamp, but I don't know where to start. Is there any information on the web that can lead me?

Thanks.

pedroskova · 28th January 2005, 02:47 PM

Quote:

Originally posted by snoopyma
Thank you for the replies. I'm interested in trying the parafeed my preamp, but I don't know where to start. Is there any information on the web that can lead me?

Thanks.

Bottlehead's forum has plenty of searchable info.

You may also want to saerch the Magnequest forum's posts.

23rd January 2005, 09:30 AM	#1
snoopyma diyAudio Member Join Date: Dec 2003 Location: Hong Kong	Output Transformers for WE-437a WOT Line Preamp I want to upgrade the output transformers for my WE-437a WOT line preamp. Some details of my preamp are: WE-437a tubes; Output transformers of EI cores; Volume control using S&B TVC; Power supply using tube rectified with choke and regulated with Allen Wright's Super-regulator board; Voltage = 195 volt, Current = 25ma; XLR input and output. In this upgrade, I prefer double-C cores. After some internet searching, some possible canditiates are Lundahl LL1689 or LL1660, Bartulloci Model C or Model E. Would anyone suggest which is the best for my case? Or any other counterparts? And the prices? Please also advise what's the difference in terms of specification and sonic quality if the laminations of the cores are thinner. The speakers that I am using are 4-way horn speaker system with 15" woofer. I want dynamic and speedy sound with wide frequency response. Any information and advice is greatly appreciated. Thanks in advance.

23rd January 2005, 11:44 AM	#3
Jaap diyAudio Member Join Date: Dec 2002 Location: Netherlands	LL1630 http://www.headwize.com/projects/sho...ciuff4_prj.htm If you lower the current to 20 mA you can use the LL1630/10 mA. I am using this as a pre-amp and it is superb. You can also try the 5842 and 6H30 tubes with this design. some experts say that less current gives better sound. I have some unused 1630's for sale but that's not the reason I give you this advice

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23rd January 2005, 11:01 AM	#2
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	I have used LL1660 18mA 4.5:1 in a similar setup. I find it very nice for the money. Have you considered replacing the transformer with a choke and parafeeding the S&B?

28th January 2005, 02:31 PM	#4
snoopyma diyAudio Member Join Date: Dec 2003 Location: Hong Kong	Thank you for the replies. I'm interested in trying the parafeed my preamp, but I don't know where to start. Is there any information on the web that can lead me? Thanks.

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