MC225 choke/PS question

[OneyedK]

I ordered an MC225 from a seller on the evil bay.
Shipment will take it's time (estimated beginning december), so that leaves me preparing for the worst...
Reading all there is to read on this amp, including several fine topics on this forum, I couldn't find much on the optimal values of the PS caps.
Seems most people just install the Authenticap replacements and be done with it.

Now I experienced a "bouncy" C-L-C filter more than once, so I would like to avoid that.
Maybe run some simple simulations and come to "optimal" values.
To do so, I would need the specs of the PT and the Choke.

Unless somebody already done that, and like to share it

Thanks!

 

[BillWojo]

I can't help you there but I would be very surprised if the power supply in the MC225 is not up to snuff. Mac isn't your typical lower end tube amp.

BillWojo

 

[lordgarth]

I've heard rumours that the Mc225 is really not that good of an amp, can't imagine why someone would buy this relic

 

[Pio1980]

I ordered an MC225 from a seller on the evil bay.
Shipment will take it's time (estimated beginning december), so that leaves me preparing for the worst...
Reading all there is to read on this amp, including several fine topics on this forum, I couldn't find much on the optimal values of the PS caps.
Seems most people just install the Authenticap replacements and be done with it.

Now I experienced a "bouncy" C-L-C filter more than once, so I would like to avoid that.
Maybe run some simple simulations and come to "optimal" values.
To do so, I would need the specs of the PT and the Choke.

Unless somebody already done that, and like to share it

Thanks!

Mac probably spec'ed optimum values in the design, but it's usually ok to up the power supply capacitor ratings by 50-100%

 

[nj pheonix]

I never had a 225 on my bench. I have followed several rebuild threads. I also have heard completely stock value rebuilds. While i'm i'm not entirely familiar with the "bouncy C-L-C filter you're describing. I Don't believe the Mac would fall into that category. I think you'll be quite pleased (with reasonably efficient speakers).

 

[OneyedK]

I've heard rumours that the Mc225 is really not that good of an amp, can't imagine why someone would buy this relic

While i'm i'm not entirely familiar with the "bouncy C-L-C filter you're describing.

I mostly work on musical instrument amps, tube recto, smallish caps and large chokes.
The "bounce" can be a pleasant dynamic response when playing, but it can be an annoyance and the amp can become a one trick pony.
This mostly happens with caps too small, but I also experienced it with caps too large, the only way to tame the "bounce" was to damp the choke (added series resistance).

The Mac seems much better, looking at the (very) positive reviews of owners.
Part of the problem is already solved with SS rectification (wich I also use in my EL84PP and 6V6PP amps),
but still, I would love to verify the proper dynamic response of the C-L-C PS of the MC225.

You have to understand, waiting time is killing me, biting nails and browsing to schematics.
Won't stop until I have the amp safe in my home...

Guess I'll have to measure the choke myself :s

 

[Pio1980]

You may be overthinking this as a problem that doesn't exist. McIntosh made the most thoroughly engineered true laboratory grade amplifiers on the planet in their day, and they were renouned for regularly exceeding their specified performance. That this problem would occur in one of their amps in proper working order is pretty remote, imo.

 

[kaplang]

I've heard rumours that the Mc225 is really not that good of an amp, can't imagine why someone would buy this relic

You got some bad information.

 

[OneyedK]

You may be overthinking this as a problem that doesn't exist. McIntosh made the most thoroughly engineered true laboratory grade amplifiers on the planet in their day, and they were renouned for regularly exceeding their specified performance. That this problem would occur in one of their amps in proper working order is pretty remote, imo.

I'm not questioning the original design values, I'm asking myself (and you all) if I will not be introducing problems when substituting the 150uF caps with 250uF (voltage doubler)...

 

[Pio1980]

I'm not questioning the original design values, I'm asking myself (and you all) if I will not be introducing problems when substituting the 150uF caps with 250uF (voltage doubler)...

I doubt it, I would try it.