2275 Sparkos Upgrade

[MikeGarofalo]

I have two 2275's I'm refurbishing. In the first unit, replaced all electro-lytics on the power supply, pre-amp tone board and both amp boards, along with the standard replacement transistors on those boards. Also installed the Sparkos amp upgrade on the tone board. Everything works and sounds great.
Unit #2 is stock and after a good cleaning of pots and switches works well.

Here's my situation. Unit 1 with all the upgrades does not play as loud or has the "punch" that the stock #2 unit has. After using pre-amp from #2 into mains #1 and vice versa, the "issue" is in the #1 preamp board with the Sparkos upgrade. I know many AK'ers have used this upgrade in Marantz gear with good luck. Has anyone noticed a similar reduction in overall power/volume?

 

[patfont]

What I would do, remove the Nichicon KA/KT! When I did my cap shoot out I was looking for an Audio Grade 105 degree cap and they seemed perfect.
Problem was sonically they are mediocre at best.

Step one: Replace the KA/KT with Elna Silmic II, Nichicon KW or FG which ever you prefer. (I like the Silmic II) See if that restores the punch?

Step two: As smart as and how good the upgrade is the gain is probably not the exact as the originals.
Reinstall the stock IC's.
See if that gives you your gain back?

If the new caps restore the sonics and gain is not an issue see if you prefer the upgrade.

 

[MikeGarofalo]

thanks, I'll give that a shot. I actually just ordered Silmic II's for the power supply. I'll let you know how it works out.

 

[Skywatcher]

thanks, I'll give that a shot. I actually just ordered Silmic II's for the power supply. I'll let you know how it works out.

Do NOT use Silmic II for power supply duty. They are the wrong type of capacitor. Only use them in the signal path. Or use UKL (Low Leakage) in the signal path. I like Silmic II in some units, UKL in others. But Silmic II take a while to "open up". So wait a few weeks before evaluating their "sound".
Use Nichicon UPW, or equivalent Low ESR capacitors for power supply/power circuit duty. Clean power makes everything else sound better.
As far as the "punch" difference goes, replace the signal path in/out carbon film resistors with 1% metal film on the tone board, and the input resistors on the amps.. The "stock" resistors could be a bit high in value. Plus the volume pots can be slightly different between both units causing the volume "curve" to be at different rotational positions. Rarely are 2 units the same when run side by side.
Remember, any "sound" is always a personal preference. What one person "loves", another will find distasteful, or something in between. It's YOUR ears that matter in the end.

 

[patfont]

Do NOT use Silmic II for power supply duty. They are the wrong type of capacitor. Only use them in the signal path. Or use UKL (Low Leakage) in the signal path. I like Silmic II in some units, UKL in others. But Silmic II take a while to "open up". So wait a few weeks before evaluating their "sound".
Use Nichicon UPW, or equivalent Low ESR capacitors for power supply/power circuit duty. Clean power makes everything else sound better.
As far as the "punch" difference goes, replace the signal path in/out carbon film resistors with 1% metal film on the tone board, and the input resistors on the amps.. The "stock" resistors could be a bit high in value. Plus the volume pots can be slightly different between both units causing the volume "curve" to be at different rotational positions. Rarely are 2 units the same when run side by side.
Remember, any "sound" is always a personal preference. What one person "loves", another will find distasteful, or something in between. It's YOUR ears that matter in the end.

Three schools of thought:

Totally technical-KL PW PM I get it
All out Audio-Silmic II (by the way better then the stock caps that have lasted about 50 years)
Sanity-In the power supply circuit if the cap is in the circuit with filtering for the regulated power supplies (In this case 13.4V/35V circuit)
I prefer/use and they have a sonic advantage Nichicon KG if it's a 470uf cap, and Silmic II if it is a 330uf cap.
For the rest of course Nichicon PM or PW.

So"Yes" use Silmic II in the power supply in certain locations.

Remember this is a P/S for a piece of audio not a computer.

Hope this helps

 

[MikeGarofalo]

I've read multiple opinions on this forum about Silmic II's in the PS board. I'll admit they are older threads, but people have used them and from what I've read had very good success. I guess I'm a bit confused now.

 

[patfont]

I've read multiple opinions on this forum about Silmic II's in the PS board. I'll admit they are older threads, but people have used them and from what I've read had very good success. I guess I'm a bit confused now.

You will be good to go with Silmic II, don't sweat it!

 

[MikeGarofalo]

Do NOT use Silmic II for power supply duty. They are the wrong type of capacitor. Only use them in the signal path. Or use UKL (Low Leakage) in the signal path. I like Silmic II in some units, UKL in others. But Silmic II take a while to "open up". So wait a few weeks before evaluating their "sound".
Use Nichicon UPW, or equivalent Low ESR capacitors for power supply/power circuit duty. Clean power makes everything else sound better.
As far as the "punch" difference goes, replace the signal path in/out carbon film resistors with 1% metal film on the tone board, and the input resistors on the amps.. The "stock" resistors could be a bit high in value. Plus the volume pots can be slightly different between both units causing the volume "curve" to be at different rotational positions. Rarely are 2 units the same when run side by side.
Remember, any "sound" is always a personal preference. What one person "loves", another will find distasteful, or something in between. It's YOUR ears that matter in the end.

Thanks for the suggestion Skywatcher, I'll check the resistor values on PE-01 and replace as needed. Can I ask if there's an easy way to know which resistors are carbon film? I believe they are the "square" looking ones, but not sure and SM lists resistance only, not resistor type. I've swapped tone board from the "good" to the "bad" 2275 and the issue definitely follows the board that has the Sparkos and other upgrades, so it can't be volume pot, power supply, components on the amp boards as suggested. I did use Solen 1 uf MKP's at the inputs on PE-01, may change back to films there to see if there's any difference. I doubt it, had good luck with MKP's there in the past.

 

[Skywatcher]

Thanks for the suggestion Skywatcher, I'll check the resistor values on PE-01 and replace as needed. Can I ask if there's an easy way to know which resistors are carbon film? I believe they are the "square" looking ones, but not sure and SM lists resistance only, not resistor type. I've swapped tone board from the "good" to the "bad" 2275 and the issue definitely follows the board that has the Sparkos and other upgrades, so it can't be volume pot, power supply, components on the amp boards as suggested. I did use Solen 1 uf MKP's at the inputs on PE-01, may change back to films there to see if there's any difference. I doubt it, had good luck with MKP's there in the past.

It just might be the Sparkos have lower gain. As long as you can go full throttle into clipping, it won't hurt a thing. I put the Sparkos in 2 of my Sansui 9090DB and had no issues with "lower volume". Maybe contact them and see what they have to say about it.
As far as the Silmic II in the power supply, as long as they filter the ripple they'll be fine. You'll have to look at the spec sheet(s) and see what the ripple current capabilities are. If high enough, then use 'em and enjoy the music.

 

[MikeGarofalo]

Yeah, Andrew from Sparkos suggested the gain should be the same.....so it's still a mystery. I'll have to grab a sine wave generator and start probing and comparing good to bad 2275's. As you said earlier, bottom line is if your ears enjoy the sound then who cares....but the technical side of me really wants to know why the two are different....so I'll probably keep at it until I find something.

 

[ttbccw]

I'm also restoring a 2275. I also used the Sparkos Labs upgrade. I only have one unit, but I haven't noticed a drop in volume from before the change. I also replaced the electrolytic caps, input film caps, and all the other film caps. All the transistors on that board too. I don't know if that makes a difference. Just that you might have to signal trace each board to see where the volume drops.

 

[MikeGarofalo]

In chasing down this gain issue, I started probing the power supply and noticed the output at at J806 is reading slightly lower than the 13.4vdc shown on drawing. I'm reading 13.17vdc. It looks like the 13.4 feeds the AM and FM circuits mainly, but wanted to see if anyone thinks this is pointing to an issue with the PS or something else.
Thanks

 

[rBuckner]

In chasing down this gain issue, I started probing the power supply and noticed the output at at J806 is reading slightly lower than the 13.4vdc shown on drawing. I'm reading 13.17vdc. It looks like the 13.4 feeds the AM and FM circuits mainly, but wanted to see if anyone thinks this is pointing to an issue with the PS or something else.
Thanks

I doubt it. This voltage is all over the place from unit to unit, like about 12.5 to 14.5.

 

[MikeGarofalo]

Pretty much what I thought, but wanted to be sure.
Very much appreciate your input.

Take care.