Matchless Phoenix

[jcat5503]

Anyone have the schematic for the ef86 side?

I know it's close to the DC30 ef channel.

Cant find it any where!

Thanks!

[Structo]

Have you seen this one?
It's hand drawn but has the EF86.

http://www.schematicheaven.com/newamps/ ... 30_old.pdf

[jcat5503]

Yeah I have checked that schematic out.

I know the two ef86 channels are similar, but I'm just not sure what values were changed to what is all.

The DC30 uses a quad of el84's, whereas the Phoenix use two el34's. The channel on the phoenix was tweaked for the 34's. I know the components we changed for the tone selector switch

[Darkbluemurder]

The channel on the phoenix was tweaked for the 34's. I know the components we changed for the tone selector switch

Do you mean the TopBoost/12AX7-Channel or the EF86 channel - I guess the latter because the TopBoost channel does not have a tone selector switch?

I wonder whether Matchless changed the PI/power amp in the Phoenix to accommodate the EL34 tubes. That would have been more logical to me instead of tweaking the preamp. I doubt that they did because they used the exact same PI in the other EL34 models (Chieftain, Clubman), too.

Cheers Stephan

[jcat5503]

Do you mean the TopBoost/12AX7-Channel or the EF86 channel - I guess the latter because the TopBoost channel does not have a tone selector switch?

I wonder whether Matchless changed the PI/power amp in the Phoenix to accommodate the EL34 tubes. That would have been more logical to me instead of tweaking the preamp. I doubt that they did because they used the exact same PI in the other EL34 models (Chieftain, Clubman), too.

The EF86 channel. I am not really sure man. They probably didn't. I have heard that the output section on the Chieftain isn't a really good design, but that's subjective. I've got a schematic for that, but no Phoenix.

From what i've heard, Matchless just tweaked some of the values on the tone switch to accommodate for the EL34's.

[Darkbluemurder]

I have heard that the output section on the Chieftain isn't a really good design, but that's subjective. I've got a schematic for that, but no Phoenix.

From what i've heard, Matchless just tweaked some of the values on the tone switch to accommodate for the EL34's.

Apart from the too low value power tube cathode resistors which tend to burn the output tubes very hot I don't see any technical errors in the Chieftain output section. The PI which initially was designed for the higher gain EL84 may not be able to drive the EL34 tubes hard enough to distort but that is a matter of taste and application of the amp. And, it is easy to change by changing some resistors in the PI.

The tone switch selects the coupling cap after the EF86. From a gut shot I have seen it looks like they add a electrolytic coupling cap (probably 1uf/500V) between the EF86 plate and the caps on the tone selector switch to change all values. That would make the effective values slightly smaller and reduce bass.

[Andy Le Blanc]

A pentode stage has a high impedance, the coupling cap can be made much
smaller and still have the same lo end response.

Cathode bias is ok to run the tube to the wall, static condition draws the most current.

How do they set up the power side?, How did they load?.
Did they use the load to double the reflected impedance and present the
tube with a reduced DCR, that the tube sees in relation to the impedance?.

[Snapcase]

AFAIK the Phoenix it's only a C30 preamp with a chieftain power amp (including the PI). Look for those two schems, put them together and you'll have a Phoenix.

Same component values throughout. Though I've seen C30s having either 220K/1M or 330K/2M2 for the EF86 plate and screen resistors respectively, the common value used by Matchless is 330K/2M2. I personally prefer the 220K/1M combo for a slightly warmer crunch.

PS, In my experience a full six position tone switch is not needed in most cases. Three or four values are enough to get the low end tight at any volume. The lower setting give a bit too flab sound even setting the amp low. and the upper two use make it too thin even cranked. Three positions is the way I go with this control borrowed from Matamp. Originally called Depth on the Matamp and early Orange amps faceplates.

[azatplayer]

I played one of these in store, really great amp. I should build one too!
I took a few pics of the one in store some time ago...its sooo busy inside with that military wiring, impressive as hell tho.
I just did a plexi in a tagstrip style wiring, a little scary at first, but i think i might stay with this style.

[Darkbluemurder]

AFAIK the Phoenix it's only a C30 preamp with a chieftain power amp (including the PI). Look for those two schems, put them together and you'll have a Phoenix.

That's what I thought, too.

PS, In my experience a full six position tone switch is not needed in most cases. Three or four values are enough to get the low end tight at any volume. The lower setting give a bit too flab sound even setting the amp low. and the upper two use make it too thin even cranked. Three positions is the way I go with this control borrowed from Matamp. Originally called Depth on the Matamp and early Orange amps faceplates.

I fully agree. A bass shelving control like they did in the Clubman and Chieftain would do a better job since it is completely adjustable. The only thing is that they specify a 1MRA pot but no problem: just take a 1MA and wire it backwards, i.e. pot on zero provides most bass and as you turn up the pot the bass gets progressively thinner. I used this control on my Chieftain build and really like it. .

Cheers Stephan