[borism]

Still working on my Almarro that I got earlier this year. In June I replaced the 0.47 uf coupling caps with Russian K40Y-9 PIO ones.




This seemed like a nice improvement. Since then I was thinking about replacing the 0.22 uf coupling caps but was going back and forth between Russian PIO and FT-3 teflon ones. I ordered both but when they arrived I realized the teflon FT-3 caps were just to large for the tight space. So, I ordered Jupiter copper foil caps. Today, they finally went in.




It's to early for a real assessment but two initial impressions are of a larger soundstage and music seeming louder on the same setting. Certainly, nothing negative. 
 

[shaizada]

Thanks for posting this!

I'd love to hear your impressions as you put on more time with the mods in place.

I have the same amplifier and think its gorgeous sounding, even stock.

[borism]

The reason I decided to try Russian PIO caps in the 0.47 uF position was seeing pictures of early stock versions of this amplifier equipped with K42Y-2 (green color) PIO caps by the factory/designer. The difference to the K40Y-9 caps is that the K42 use metalized paper while the K40 use aluminum foil and are therefore preferred by some. However, the fact that the designer thought these PIO caps to be synergistic gave me confidence to try.

I also didn't want to use the same PIO caps in both coupling positions in order to avoid enhancing possible deficiencies in the frequency extremes.

[Tyson]

Keep an eye on those Jupiters.  I had a pair in my Almarro and they melted.  Switched over to Miflex copper caps and no problems since. 

[morganc]

Not meaning to hijack your thread but would you mind sharing what changes have you noticed with the mods and what mods have been most beneficial?  What % improvement would you put on each change if forced to do so?  I have a base model and trying to decide to sell or mod.

[FullRangeMan]

If you have a handy experiencied tech ablê tô repair it could worth tô keep, this amp have a lot of parts in a small chassis, not easy tô repair it.

[morganc]

If you have a handy experiencied tech ablê tô repair it could worth tô keep, this amp have a lot of parts in a small chassis, not easy tô repair it.

Huh?  My unit is not damaged.  I'm asking for feedback on mods to the Almarro and what mods are most beneficial and such....

[FullRangeMan]

Huh?  My unit is not damaged.  I'm asking for feedback on mods to the Almarro and what mods are most beneficial and such....

If your amp is good, why should you replace parts that are working perfectly?

Better price/value mod are tube rolling the input tubes and not need move the amp tô a repair shop.

[Tyson]

Not meaning to hijack your thread but would you mind sharing what changes have you noticed with the mods and what mods have been most beneficial?  What % improvement would you put on each change if forced to do so?  I have a base model and trying to decide to sell or mod.

The biggest improvement I noticed on mine was when I removed the volume pot, signal switch and computer-quality wiring from the signal path.  Next was changing out the coupling and output caps for Miflex copper, and last was changing the RCA connectors for WBT and the binding posts for Furutech. 

Overall it took a pretty good sounding amp to an outstanding sounding amp. 

[morganc]

The biggest improvement I noticed on mine was when I removed the volume pot, signal switch and computer-quality wiring from the signal path.  Next was changing out the coupling and output caps for Miflex copper, and last was changing the RCA connectors for WBT and the binding posts for Furutech. 

Overall it took a pretty good sounding amp to an outstanding sounding amp.

Thanks Tyson. Agreed, it's pretty good sounding now...appreciate the feedback. I got mine for a screaming deal and it feels like a good hobby. Any resources or threads related to the mods that you could share?

[borism]

Keep an eye on those Jupiters.  I had a pair in my Almarro and they melted.  Switched over to Miflex copper caps and no problems since.

Thanks Tyson! This was a concern I had before getting the Jupiters. One reason for considering the Russian FT-3 teflon capacitors was the thermal stability. Can you say which ones (0.47 or 0.22 uF) melted and what symptoms you noticed?

[Tyson]

Thanks Tyson. Agreed, it's pretty good sounding now...appreciate the feedback. I got mine for a screaming deal and it feels like a good hobby. Any resources or threads related to the mods that you could share?

There should be a schematic with amp, if not I can tell you the main thing to be aware of is if you bypass the volume pot, it's 250ohm.  So put a 250ohm resistor in it's place if you do bypass it.  The rest of the mods are just things I've done on a ton of other amp, so I'm pretty comfortable doing them. 

My strong recommendation is to only do 1 mod at a time.  Do a mod, listen for a while, make sure it's working well and stable and sounds good.  Then move on to the next mod.  Doing it this way allows you to zero in on any mistakes and back them out more easily of something doesn't go right. 

Thanks Tyson! This was a concern I had before getting the Jupiters. One reason for considering the Russian FT-3 teflon capacitors was the thermal stability. Can you say which ones (0.47 or 0.22 uF) melted and what symptoms you noticed?

.47 and .22 both oozed brown wax material that dripped all over the bottom of the case.  I cleaned it up and pulled the caps as soon as I saw that.  I LOVE copper caps in this amp, so I went with the much more robust Miflex 600v copper caps instead and they've handled a lot of abuse and are standing strong.

"What type of abuse" you ask?  As a stress test I left the amp on 24/7 for more than a week.  And no problems.  So the Miflex caps are very robust.  Bonus?  They actually sound better than the Jupiters, too.  Extra bonus?  They are less expensive.

As an extra safety step with this amp, I recommend elevating it with some extra tall footers.  It gets so damn hot that ANY extra ventilation you can give it by elevating it off the shelf is going to prolong it's life.   

[borism]

Thanks again Tyson. If you have a picture of the underside of your amp or can take one I'd greatly appreciate it. The Myflex caps are significantly larger than the Jupiters and I just would like to see how it all fits in.

[borism]

Unfortunately, while eating breakfast and listening to radio there was a sudden shift in sound with emphasis on high frequencies. Given the warning about capacitors melting I shut off the amp and let it cool down before looking underneath.

This is what melting wax capacitors look like.




One can see the wax droplets forming on what would be the underside. Fortunately, I posted here and received the heads up about this possibility.
The Jupiters sounded good to me but in this application lasted less than 3 days. I think that I might just go all Russian military on this amp and see how to fit in FT-3 caps if I can.

[Tyson]

The FT-3 caps are good and certainly robust!

If you ever want to try copper again, the Miflex are good, but if you're shy about using anything with wax or oil, then Audyn makes a very nice copper cap using poly as a dielectric. 

And VH Audio makes a copper/teflon cap but it's $$$.

[borism]

It was more complicated but I found space for the huge 0.22 uF FT-3 teflon capacitors. Music is playing right now and they are sounding brighter than the Jupiters without burn-in. In my prior experience burn-in takes a very long time with the teflons.




Hopefully, this will last!

[Jon L]

In my mind, FT-3 teflon caps are truly the budget champs.  I just wish they had used wire leads instead of those metal tabs.
Also, it looks like the caps are located right below the power tube socket.  6C33C tubes get quite hot, and Jupiter copper caps are rated to 80 degrees C, so I'm not surprised..

[FullRangeMan]

Just one 6C33 works at about 220ºC:
https://www.youtube.com/watch?v=EaWHqNy7_5c

[borism]

I tried to estimate beforehand the temperature within the amplifier but obviously incorrectly. The electrolytic caps within are rated 85*C. When the amp has been on for a few hours the top surface between the power tubes can be touched for 2-3 seconds. So I estimated it to be between 50 - 60*C. Apparently, the inside temp close to the power tubes must have been above 80. Live and learn...

[FullRangeMan]

The 6C33 and other big tubes of this size or larger dissipate a lot of heat through the wiring, so the wiring cannot be stranded, it must be thick solid wire.