Originally posted by kptseng
Hi Beppe, Overall do you think it is a worthwhile effort in terms of cost+time over improvement?
Hello to you !
Well, I have time and money to waste.
No seriously, these were my reasons:
1) the AP10 has a nice sound that nevertheless I find weak in the bass
2) it has a nice darlingtons output pair per channel. Given that there are not current limiting circuits these pairs can give a good current to the load
3) the main difference between the AP10 and AP30 seem to be a bigger case and stronger power supply
4) 10 strong and good watts can be enough with sensitive speakers in a small room like mine
5) the original AP10's transformer is a very little 20VA (!)
On this basis I decided to start with an external more powerful transformer.
Now it is working with a 630 VA (24V+24V) isolation transformer from Legrand. Ok I have exaggerated a bit.
Just to be sure that the transformer it is not the weak point now.
How did you solve the problem of the acrylic case?
Do you use a new case all together or cut open the acrylic case which are glued together?
I opened the cover that is in aluminum.
I am still using the original case with an umbilical cord to the external transformer.
By the way, what speakers are you using with teh NVA?
A pair of old Tannoy DC-100 equipped with a 8" dual concentric driver and bass reflex loaded.
Quite sensitive. About 88-89dB/1W.
I own a AP10P and very happy with it.
Like you I once thought of increasing the transformer capacity but was put on hold due to the case.
there is no enough space inside for a bigger transformer.
A more convenient choice would be to upgrade an AP30 that has a lot of space inside.
But it is about twice the price of the AP10.
The circuits of the two unit appear so similar to me.
I think that the main difference is in the gain of the two circuits.
That is the value of the feedback resistance.
I believe that also the voltage rails could be identical.
Also I am thinking of trying their A40 mono block as NVA allow trade-in
I like the two monos solution better than a single stereo unit.
Two A40 monos should sound terrific.
But it seems to me that NVA has undersized the power supply a little, even in the A40 that should have a 120VA (?) transfo.
I would double it.
Are you thinking of upgrading the smooting caps?
On the basis of my experiment I think it is mandatory.
A pair of good 20.000uF caps should be a good start.
First of all I do not believe to things like too much capacitance in a power supply.
Just look at this one :
http://www.audioclub.it/h/audio/prodotti/MARKLEVINSON/PICSML/ml33esplosob.jpg
Presently I am using the original caps and with the original diodes bridge.
But I definitely think that the original 2x4700uF caps should be replaced with bigger ones.
But the space is the main limiting problem.
If yes look at the BC Component 114 series.
I had great suceess with these in my previous Naim upgrade.
thank you very much for your kind and valuable suggestion.
My intention would be to pull out the original transfo e caps and place inside the amp a new stronger bridge (25 o 30A) and two new caps.
Thanks and regards,
beppe
Hi Beppe, Overall do you think it is a worthwhile effort in terms of cost+time over improvement?
Hello to you !
Well, I have time and money to waste.
No seriously, these were my reasons:
1) the AP10 has a nice sound that nevertheless I find weak in the bass
2) it has a nice darlingtons output pair per channel. Given that there are not current limiting circuits these pairs can give a good current to the load
3) the main difference between the AP10 and AP30 seem to be a bigger case and stronger power supply
4) 10 strong and good watts can be enough with sensitive speakers in a small room like mine
5) the original AP10's transformer is a very little 20VA (!)
On this basis I decided to start with an external more powerful transformer.
Now it is working with a 630 VA (24V+24V) isolation transformer from Legrand. Ok I have exaggerated a bit.
Just to be sure that the transformer it is not the weak point now.
How did you solve the problem of the acrylic case?
Do you use a new case all together or cut open the acrylic case which are glued together?
I opened the cover that is in aluminum.
I am still using the original case with an umbilical cord to the external transformer.
By the way, what speakers are you using with teh NVA?
A pair of old Tannoy DC-100 equipped with a 8" dual concentric driver and bass reflex loaded.
Quite sensitive. About 88-89dB/1W.
I own a AP10P and very happy with it.
Like you I once thought of increasing the transformer capacity but was put on hold due to the case.
there is no enough space inside for a bigger transformer.
A more convenient choice would be to upgrade an AP30 that has a lot of space inside.
But it is about twice the price of the AP10.
The circuits of the two unit appear so similar to me.
I think that the main difference is in the gain of the two circuits.
That is the value of the feedback resistance.
I believe that also the voltage rails could be identical.
Also I am thinking of trying their A40 mono block as NVA allow trade-in
I like the two monos solution better than a single stereo unit.
Two A40 monos should sound terrific.
But it seems to me that NVA has undersized the power supply a little, even in the A40 that should have a 120VA (?) transfo.
I would double it.
Are you thinking of upgrading the smooting caps?
On the basis of my experiment I think it is mandatory.
A pair of good 20.000uF caps should be a good start.
First of all I do not believe to things like too much capacitance in a power supply.
Just look at this one :
http://www.audioclub.it/h/audio/prodotti/MARKLEVINSON/PICSML/ml33esplosob.jpg
Presently I am using the original caps and with the original diodes bridge.
But I definitely think that the original 2x4700uF caps should be replaced with bigger ones.
But the space is the main limiting problem.
If yes look at the BC Component 114 series.
I had great suceess with these in my previous Naim upgrade.
thank you very much for your kind and valuable suggestion.
My intention would be to pull out the original transfo e caps and place inside the amp a new stronger bridge (25 o 30A) and two new caps.
Thanks and regards,
beppe