[mrarroyo]

Glad Dr. Gilmore was able to assist in resurrecting your amp! Enjoy it.

 

[Bolder]

Here is the Edcor transformer mounted on a small chassis Extreme

Same amp with transformer cover placed over the Edcor.

This amp also had the HV diodes replaced and film caps added to the output caps.

 

[Skylab]

Very nice! I do not like the look of the electric blue transformer, but it looks fine covered up

 

[Bolder]

Thank for your comments, Skylab.

I just spoke to the owner of the Extreme after he saw the photos.

He actually likes the look. Kinda like the Donald North amps with their bright blue chassis. Beauty is in the eye of the beholder

The bridge rectifier for the filaments is bolted the the back of the chassis in this amp. There was no thermal compound used. I added some thermal grease and there was a marked improvement in thermal transfer.

The new transformer is rated for 8 amps filament current. I did note that after 1/2 hour driving a pair of HD-600s the tranny was running a little warm. The transformer cover is not fastened down. I will leave it up to the owner if he wants to cover it up. I would suggest the cover be left off for additional cooling.

 

[Skylab]

Indeed - some people will love the blue I'm sure! Most importantly, it's another Extreme in the "safe" column

 

[Frihed89]

Quote:

Originally Posted by nurxhunter /img/forum/go_quote.gif [/IMG]

That sure looks like a Jeff Larson amp. He's a terrific person, builder and audioexpert. I hope you like it.

 

[Frihed89]

Quote:

Originally Posted by Skylab /img/forum/go_quote.gif Indeed - some people will love the blue I'm sure! Most importantly, it's another Extreme in the "safe" column

What were the originals rated at and which ones did you replace them with? Mine are too small, I am pretty sure, even if I ditch the high power option on my MPX3.

 

[Skylab]

The transformer I ordered from Electraprint was as follows:

$116.00 M19

Primary: 1 x 115VAC
Secondaries:
1 x 115VAC @ .4A
1 x 6.6VAC @ 8A or 2 x 6.6VAC @ 4A
Lead Length: Standard
Mounting Style: Vertical

 

[guitarplayer]

Quote:

Originally Posted by Frihed89 /img/forum/go_quote.gif That sure looks like a Jeff Larson amp. He's a terrific person, builder and audioexpert. I hope you like it.

Jef makes some really great sounding gear, indeed.

Lee

 

[nurxhunter]

Yup, from Jeff. I do in fact like it. I posted those pics because these I the amps I can;t seem to let go. Each has its own sound signature, each is 'the best'.

Back to this thread--the Extreme is my reference amongst these. Before the new internal tranny was implemented to supply the plates, I could touch and hold for a second the 6AS7G tubes--and even Bendix 6080. the Tformer did not get very hot, but quite warm.

Now with separate transformers for filaments and plates, the 6AS7 are too hot to touch almost (certainly not hold), the transformer runs much cooler supplying only the filaments and properly wired, and the Extreme sounds great, quite a bit more 'extreme' than before ( I liked it even in its weakened state before, much more so now). Certainly, the Extreme is the quietest amp I have ever owned, except for the diminutive and over-acheiving Earmax pro.

I am surprised the Edcor fit under the cover--I hear nice things about their output transformers--great for the money.

 

[Skylab]

I have five different amps that use the 6AS7G - and on all of them, if you touch the tube when it's been on for more than 10 minutes, you get burned. You should never have been able to touch and hold a 6AS7G on a properly functioning amp.

 

[Rob N]

Quote:

Originally Posted by nurxhunter /img/forum/go_quote.gif Certainly, the Extreme is the quietest amp I have ever owned, except for the diminutive and over-acheiving Earmax pro.

OT I know but the EMP is a great amp.Have you heard the Earmax Anniversary/Silver Edition?

 

[kevin gilmore]

just when you think you have seen everything, comes this extreme built as an
extreme. At least it was an extreme designed board in a MPX3 chassis.

Now i knew this one was going to be real trouble when i first saw pictures of it.
I open the thing, turn it on, no filament power, but the .15 ohm resistor while
very toasted is still conductive. But it fell right off the circuit board.
http://gilmore.chem.northwestern.edu/raffy4.jpg

So its obviously time to remove the circuit board.
But wait, the side board is soldered in from the backside
http://gilmore.chem.northwestern.edu/raffy8.jpg
http://gilmore.chem.northwestern.edu/raffy6.jpg
http://gilmore.chem.northwestern.edu/raffy5.jpg

and no way to unsolder it without brute force.
Sweet.

3 hours later...
http://gilmore.chem.northwestern.edu/raffy1.jpg

The resistor burned all the way thru the mounting pad on the left.

but did you notice the soldering job...
here is a closeup

http://gilmore.chem.northwestern.edu/raffy3.jpg

globs of solder just barely hanging on the board...

Finally 20 watts of resistor on ceramic standoff's that
should live a while.
http://gilmore.chem.northwestern.edu/raffy7.jpg

OK, further comments, it was obvious by the time this was built that
lots of the smaller transformers were burning up, so mikhail scaled up
the transformer. He scaled it up a bunch. 7.5 volts AC before the diode
bridge under load. So the diode bridge gets even hotter than the previous
units, and that poor little original 5 watt resistor is running at right around
10 watts, and still delivering only 5.8 VDC to the tubes.

my 5 watt x 4 resistors in parallel end up .125 ohm, and generate about
12 watts of heat.

Bottom line, every one of the units like this is going to do the same thing.
While the parts are cheaper, the labor is 4 times that of the other units.

If you own one of these versions you should open it up and take a look.

 

[Skylab]

YIPES! That is really, really scary.

 

[shellylh]

Holy ****, that is something else. Yikes.