My Transformers

[Rob Flinn]

Analag

All the audio Iron is sowter, but the PSU iron is Parmeko ex miltary C core oil filled (my favourite). I have all the parts apart from the 2 centre tapped pots. I was trying to get the 6386 part working first, & then the s/c amps. Are you building in the M/S matrix into yours ??

The main difficulty is just finding enough spare time to actually do a significant amount of work on it. I must say that looking at your creation has inspired me to find some time. Like you say it needs to come off the workbench & into the studio !

 

[analag]

I skipped the M/S matrix, dual mono/stereo will have to do. This is not a true copy of the 670 and I'm building it just to see how much I can mess with the original concept and get away with.

analag

 

[Rob Flinn]

I dug out the chassis & after getting the cobwebs & leaves out of it took some new pics. I had just started to put in the dc heater supply for the 6386's when it last got shelved 6 months ago. Anyhow the fresh pics show the chassis loaded with valve bases & all iron.


http://www.ashrec.com/new_page_1.htm

 

[analag]

You went too far to stop now, put half an hour into it everyday. No matter how small it is, it adds up. Normally I do my heater supply first since I hate that the most, then I do the B+, after I get those out the way I'm good to go.

analag

 

[Rob Flinn]

Normally I do my heater supply first since I hate that the most, then I do the B+, after I get those out the way I'm good to go.

That's precisely my modus operandi. I have done all the ac heater wiring, but need to build in the dc reg PSU for the 6386. Sadly I'm using an LM338k for the reg.

 

[analag]

Lots of options for the DC heater setup. I normally go with large filter caps (44,000uF) and a voltage setting resistor.
No DC heater supply implemented in this thingy, no noise problems thus far.

analag

 

[Rob Flinn]

Rowan

Question:

How are you dealing with the negative bias psu ?

I've been trying to work out what spec the transformer should be, without too much success. Any pointers ??

 

[LazyOne]

maybe a stupid question where did you get the c-cores?
i want to try winding my own but i can't find a core material source.

 

[analag]

[quote author="Rob Flinn"]Rowan

Question:

How are you dealing with the negative bias psu ?

I've been trying to work out what spec the transformer should be, without too much success. Any pointers ??[/quote]

I have (2) bias windings on my power transformer, 20V @100mA and 70V @100mA. You could use one bias supply with an LM337 to create the sidechain bias.

analag

 

[analag]

[quote author="LazyOne"]maybe a stupid question where did you get the c-cores?
i want to try winding my own but i can't find a core material source.[/quote]

http://www.alphacoredirect.com/index.html?lang=en-us&target=d3.html

Sneak peek of the front panel. I might get it engraved at some point, who knows.

The Time Constant parameters have been reworked with more flexibility in the Release structure.

analag

 

[Larrchild]

Throw a couple of Sifam vintage meters in on the left. Engrave some 1/16th black laminate around the knob area and paint the panel medium grey and you'll have a visual clone. (well almost) Then some Gen Radio knobs from Leeds and clasiic-vintage, dude!

You got an output pot?

 

[analag]

No output pot...a truley minimalist audio path. I cut the gain and gave it more headroom. Sweet.


analag

 

[Rob Flinn]

[quote author="analag"]I have (2) bias windings on my power transformer, 20V @100mA and 70V @100mA. You could use one bias supply with an LM337 to create the sidechain bias.analag[/quote]

Mmmm interesting, you must have changed things a bit to need a 70v tap ??

I think your right about using the 337. It does simplify things & will stop the rail drifting with line voltage changes.

 

[Kid Squid]

Oh Boy !

been doing 16hr shifts for the last two weeks, what a sight for sore eyes :grin:

regarding the engraving analag, if you want a traffolite style engraving, let me know !

along these lines -

Regards,
Steve :thumb:

 

[analag]

Well, it's completed and working. It must be heard to be believed, with 40Watts driving the sidechain, I think it would give the original a serious run for the money and I'm not ego trippin.

It's been fun, guys. Catch you later.

Rowan

 

[peter purpose]

**** ME..!!!!

 

[Learner]

[quote author="analag"]

Rowan[/quote]

WHOW!!! :shock:

Is this place getting hot or what?

 

[ciminosound]

Me thinks this is the "DIY Project Of The Year" winner!

:sam: :sam: :sam: :sam: :sam: :sam: :thumb:

 

[TomWaterman]

Bloodyhell!

That is ******* amazing...best project in the history of GroupDIY!

Congrats analag. You could probably sell a few of them.
Prepare yourself for all the PMs about how to DIY one now...

I'm in awe.
-Tom

 

[KingKai]

Analag!!!!

Outstanding!

I love the blue metal flake paint job! Glad to hear that it lives up to your expectations audio wise.

Man this thing NEEDS one of those blue sparkle tuck-n-roll cabinets that Kustom used to use.

Great looking job. :guinness: :sam: :guinness: :sam:

Peace - Out, Irv