Metropoulos Forum

Amazing, I can't tell which is which myself. Maybe a subtle difference, but really, I can't tell.

Damn, sounds awesome! How much burn-in time do you have on the Sozos?
Still tweaking with the latest Mallory caps, shelved?

Those Sozo caps had burned for about 2 hours total since I fired up the amp. I still like the Mallorys too, great clarity.

It's really about the whole recipe I'm finding. Use brighter parts here and compensate with darker parts there etc. Evaluating each stage led me in a different direction than sweeping the entire amp too. I had to compensate for different freq response in the power section.

Getting the freq plots to match is pretty straight forward. But making the replica clean up like the old one really took some trial and error.

George

Right on man, you nailed it! The clean up is a treat on the cranked clip, they clean up exactly the same. I bet the differences will be even less noticeable after the sozos have been played for awhile. What really gets me is how you compensated for everything, especially the tubes. Listening to the clips, I would assume both were vintage amps with old tubes and components if I didn't know one was a replica, they sound the same to me.

George, sounds dead nuts the same. Whatever you did between the YT videos and now really improved things. I wanted to get your thoughts on how this new amp may sound 2,5,10 years from now. You have done a great job cloning a 45 year old amp where the cap, resistors, etc have had thousands of hours of play time. Is there a point at which the parts don't continue to "ripen".

That's a good question. Something to consider as your philosophical aporoach to a build. Are you building an amp that sounds like the original did when it was new? Or an amp that sounds like a 50+ year old amp? In this case my goal was to build a replica that sounds like the old one does now, using 98% new parts. It would be 100% if not for three NOS ceramic disk caps.

I know what to expect as this amp breaks in over the first 10, 50, 100 hours. It should sweeten to a degree and harmonics will focus and stack up. Single note definition increases. Everything seems to come into focus.

Whether it moves away from sounding like the original remains to be seen, or heard more accurately. Maybe I have over shot the mark. I could shoot for authentic tone during the time from 100 hours to say 5,000 hours (whenever the next changes happen as thevamp ages). To be honest, I don't that answer yet.

George

Wow! I can't tell which amp is which either....They sound the same. Great job George. Do both amps feel the same when playing?

VelvetGeorge wrote:Here is a clip of the amps, using the A/B switcher. I switch pickups and roll back the volume on the guitar to show how the replica cleans up the same as the original.

Note, I called the first clip "12380 vs 12094 all on 5", but technically the volume for 12094 was on about 4.25 to match the gain.

https://dl.dropboxusercontent.com/u/646 ... on%205.wav" onclick="window.open(this.href);return false;


Then, tone controls all on 5, Volume on 10:

https://dl.dropboxusercontent.com/u/646 ... n%2010.wav" onclick="window.open(this.href);return false;


Try to guess which is which!


george

Sick work here, my favorite thread for sure! The volume on 10 clips are still pretty different though, (second one is the 12380), but that is just a matter of brighter and openness, I'll bet there is a huge stock pile of those chicklets somewhere, can you post some closer shots of them so we can start digging around?

Actually, in these most recent clips 12380 was always first, then replica second.

I do hear some subtle differences, but only when comparing amps without attenuation. My ears only hold up for about 10 minutes of that per day. 12380 does have an extra openess and chime, a little more space around the notes if you know what I mean. Not drastic or obvious, but it's here. Probably attributed to NOS tubes and caps.

George

Wow, you got me on that one (but, I'm still the student here)! Just a testament to your work here. I can appreciate the challenge of creating this tone with current production components, but where exactly does that extra richness of the 12380 lye? Could it be as simple as pre-tinned wire vs. regular old stranded wire like 7/30 22awg? Are modern caps and resistors too pure in there makeup? Still, on another note, how much are you letting the replica burn in, it would be cool if you burned it for a solid week and did another comparison just on that alone.

Whats odd (or maybe not) George is I prefered the 12380 on the dirty tone but the 12094 on the cleans.

They are so damn close the only way to really tell is bouncing the toggle back and forth. Straight out on one amp you wouldn't be able to tell the differnce.

All I can say at this point is that everything matters. Wire definitely has a sound.

Old parts were typically made with more inductance, where as today they are low or non-inductive. That surely creates complex filters in each part of the signal path.

I am convinced I can replicate the frequency response of the original using modern components and tubes. The intangible tonal qualities: depth, randomness, musical overtones, feel etc are almost definitely a product of those old parts, tubes, worn filter caps.

george

It's interesting thinking about how the modern parts will age compared to the now vintage ones. Talking about inductance really interests me. I'm not as up on electronic engineering as I would like to be, but I would imagine that they way individual components change will affect the overall circuit. So taking inductance into consideration, I wonder how differently the Replica will age compared to the original amp. It's really exciting and I'll enjoy seeing how a Replica settles in with each passing year.

George, I mentioned the Mallory caps, but curious about your latest take on the Standard vs the Vintage Sozos.
Vintage better fit the *recipe*?
Have a 12 series in the oven, and am torn about the currently available caps.

I must say that this is spot on (very subtle difference) the one with the sozo !!!!
I'm impressed !!

What is the value of the bright cap on the 68 ? (it don't sounds like 500pf

Very Cool indeed