Metropoulos Forum

Recently watched a couple of clips of this amp and it sounds pretty good to me, cleans up well but is quite tight and has enough gain for me.

I have an 18/20w head project lined up (for some mythical time in the future ) with my others, but as I like to plan ahead
As I already have a stock 18w 2x12 and 18 EF18 TMB 1x12
Want to build one of these. Looks like a SLO atomic front end but stock type power section
Any ideas?

From the gut shots ive seen id say BE front end with a cathode biased pair of el84s. No choke on the current production model, just a dropping resistor.
Theres an average quality gut shot included in the Mark Day demo on youtube....should give you plenty to go by.
Start with a higher than average plate resistor on v1a, 100k on the rest
Cathodes....try 2k7/.68...2k7/.68......820r/.68
2n2 couplers between the first 3 stages although maybe something closer to 22n depending on final tweaking.
470k/470k voltage divider between v1a and v1b
1m gain pot with 470k/470k divider between v1b and v2a
Check the pics for and bypass micas.
You could lower the first voltage divider values if you want the c45 type voicing. 68k/68k
18w output section and tweak to taste.

Or i could be totally wrong.

evh0u812 wrote:From the gut shots ive seen id say BE front end with a cathode biased pair of el84s. No choke on the current production model, just a dropping resistor.
Theres an average quality gut shot included in the Mark Day demo on youtube....should give you plenty to go by.
Start with a higher than average plate resistor on v1a, 100k on the rest
Cathodes....try 2k7/.68...2k7/.68......820r/.68
2n2 couplers between the first 3 stages although maybe something closer to 22n depending on final tweaking.
470k/470k voltage divider between v1a and v1b
1m gain pot with 470k/470k divider between v1b and v2a
Check the pics for and bypass micas.
You could lower the first voltage divider values if you want the c45 type voicing. 68k/68k
18w output section and tweak to taste.
Or i could be totally wrong.

Thanks

Yes the still image from the Mark Day review is the pic I looked at to make me think SLO (I could make out the 220k/100k plate resistors on V1), the 470k/470k divider. The coupling caps could be 22n. I have a schem for a Soldano Atomic at the moment which puts the gain pot between V1a and V1b rather than v1b and V2a?http://www.guitarelectric.eu/schematy/F ... ml#schemat
It shows a 1.8k/1uF cathode combinations for V1a and V2a with 2k7 on V1b on the schem I have but if you are familiar with the BE schem I am more than happy to listen!

Im sure if you compare the picture to my suggestions, youll find them reasonably close. Maybe some value changes here and there to account for the different power section.

edit......just looked at a still pic from the video, the cathode bypass caps are hard to tell what values have been used.
Gain pot is definately between V1b and V2 on the Taco and BE so quite different from the Soldano. This is part of the reason the C45 switch works so well by lowering the first divider from 470k to 68k.
Just looking at it, Im guessing that's not a Metro built one........

evh0u812 wrote: Just looking at it, Im guessing that's not a Metro built one........

But hey, it's handwired in the USA, so it's gotta be great work, right?

demonufo wrote:

evh0u812 wrote: Just looking at it, Im guessing that's not a Metro built one........

But hey, it's handwired in the USA, so it's gotta be great work, right?

haha, Im not touching that one.
But to be honest at that price bracket, Im not sure you could expect more for a hand wired amp.
Although for $1400......Ill just keep building my own.

evh0u812 wrote:Just looking at it, Im guessing that's not a Metro built one........

I certainly hope not I know George's shop does some Friedman stuff but I thought mainly Metro-Friedman?

I have an original RS OT and an amppower 290-0-290PT and will go with diodes rather an EZ81 although making it switchable like the Cornell 18/20 has an appeal too.

I believe George was originally going to do the assembly but Dave Friedman decided to do it in house so he could keep an eye on quality control and test each one personally himself. Read that from a post Dave put up on another forum.
No matter how you look at it its a great amp for the money if you don't know which end of a soldering iron to hold.

evh0u812 wrote:....if you don't know which end of a soldering iron to hold.

Geez, no wonder my hands hurt....

Here are some gutshots:

http://www.slocloneforums.com/viewtopic.php?f=6&t=6592

The Pink Taco has a great front-end, but what makes it special (IMHO) is that it has enormous transformers for an amp that size. I don't think I have ever seen another amp with two EL-84s have that much punch and that deep a low-end. It feels, sounds and responds like a 100 watt amp.