Dear SET forum,

I have been seriously considering three valve amp designs over the past two weeks.
The Darling,

http://www.diyparadise.com/Darling.html

This is a very well liked, simple straightforward circuit, cheap parts (Great sound) but low power.

A KT88 SE as suggested recently and described here

http://pmillett.addr.com/elinear.htm

and an Australian design known as The Tweaker. (No web page available) The design like the two above is relatively simple. It is a two stage using a 6SL7 to drive one of the following;

KT88, a KT66, EL34 or a 6L6. The user simply tweaks the bias to suit the chosen output. (Each channel uses just 11 resistors and 3 caps)

The designer Earle Weston (Melbourne) (eBay alias ehtcom) also winds his own transformers and is able to supply all parts as required. The power output will vary between 9.5-14W in pentode mode. (Approx half this in triode mode)

With so much local support, design and parts supply I have decided to build a dual mono version of the Tweaker.

I would like to display the circuit diagram but I should ask the owner first. I will be getting the power supply parts made up over the next few weeks.

I will probably be pestering this forum with lots of questions when I start putting it all together. I hope you are all patient.

Thanks for all your great advice so far

Howard
http://www.eastmarinedrive.com

One of Earle's KT66 designs

Howard, I'd be disappointed if you didn't pester.
Looking forward to see the design and your build.

gar.

I will be more than happy to keep you all informed. Its certainly a very exciting design with a potential to suit all sorts of listening tastes.

Earle builds them as a integrated 2 input unit. I really prefer the look of 2 mono amps.The tweaker is usually supplied with a multimeter so that the user can set bias. I would like to build the voltmeter into the chassis.

Probably using the RS 1V meter. Please see the link

• RS voltmeter

Yes indeed we do!

The transformers are now wound and will be arriving shortly. Five minutes I bought some essential bits on eBay.

It should be a very interesting project

Howard

ANY TIPS RELATING TO BUILDING THE CHASSIS?
CAN YOU RECOMMEND AN OLDER STYLE 6SN7?

I have gathered all the Transformers and Chokes. These have been wound by Earle Weston down in Victoria. Over 7.00kg weight for each mono amp. The passive components are ready and these include Nichicon Muse caps and carbon resistors.

I have bought at least 3 different sets of 6SL7 twin triode. I am trying to find some Sylvania types which sound nice. I have some KT66, KT88 and GZ34 rectifiers (new Chinese Valve Art, supplied by eBay user cellvalve)

http://search.ebay.com.au/_W0QQsofocusZsoQQsbrftogZ1QQfrppZ50QQfromZR10QQsacatZ-1QQcatrefZC6QQftrtZ1QQftrvZ1QQsadisZ200QQfposZPostcodeQQsellerZ1QQsassZcellvalveQQfltZ9QQfsopZ1QQfsooZ1QQcoactionZcompareQQcopagenumZ1QQcoentrypageZsearch

I enjoyed using the VA KT66 in my old Quads. I have also found some nice quality valve sockets in HK

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=6526398855&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1

and some cheap silver plated copper (Teflon coated) wire from the US.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=5772513112&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1

I still need to get hold of some switches, pots (bias) and the RS virtual voltmeters which I mentioned earlier.

Chassis: It will basically be about the same size as a REFLEX photocopying paper box lid! Its probably going to be made out of a heavy grade Al (easy to work etc) the transformers supplied by Earle are already finished in his standard gold fleck paint. I would like to powder coat the chassis once all the hardware holes are drilled/ cut (charcoal grey) apparently you can powder coat Al The gold/grey should be well set off by the back lit green meters placed in the front panels

http://www.rs-components.co.uk/electronic-components-uk/590299179-RS-Components-1Vdc-Virtual-Analogue-Voltmeter-LED-Backlit--Automation-Panel-Meters-Voltmeters-Digital-Modules-Single-Mounting-Hole.html

The chassis will be fairly slow going since I am moving into the end of Term. This means lots of report and exam marking.

I recently decided to delete my entire website because it was simply out of control and getting far too big. I will be adding lots of pictures to my new site once the project starts to take shape

Howard
http://www.eastmarinedrive.com

• MY NEW WEBSITE

Dear Colin,

I am sorry the URLs don't appear to work here

Here is a picture of come collected parts

I put my amp on hold. I decided I needed some more efficient speakers before I went to a low power amp. Right now I'm trying to assemble a pair of Altecs with the help of a few AudioRoundTable members. As soon as these are done I'm back on the amp.

Sorry to see you took your old web site down. There were so many cool projects......Colin