what is the best matched affordable power amp for NS 10s??

Jim Williams · Post by **Jim Williams** » Tue Jan 01, 2013 11:52 am

For those wishing more bass extension in their Adcom amps, replacing the gain set 47 uf cap with a 100 or 220 uf/100V cap with quality film bypass caps will remove all the phase shift and extends bandwidth to below 2 hz.

For greater bass energy, replace the 10,000 uf caps in a 545 with 22,000 uf caps, replace the 15,000 uf caps in the 555 with 30,000 uf.

The Adcom's are Nelson Pass designs like Hafler. The main difference is AC coupling in Haflers and mosfet output devices (which I really hate the sound of). I've also had recent Pass Labs amps in and they also failed the A/B test against the fixed up Adcoms. He also used mosfets in place of BJT's. Mosfets are non-linear devices that rely on heavy negative feedback to obtain a decent THD spec, but they still sound harsh to me. You will need better than NS-10's to hear the truth from these amps.

nestle · Post by **nestle** » Thu Jan 10, 2013 12:15 pm

WooHoo
Hafler P-3000 Trans Nova arrived today $270 via ebay with free shipping.
Will follow up soon after hook up!

nestle · Post by **nestle** » Thu Jan 10, 2013 9:40 pm

Really really like the Hafler amp, so great. NS10 come to life like never before. excellent suggestion!!!!!!!!!!! LOVING IT!

calaverasgrandes · Post by **calaverasgrandes** » Fri Jan 11, 2013 11:15 am

Jim Williams wrote:For those wishing more bass extension in their Adcom amps, replacing the gain set 47 uf cap with a 100 or 220 uf/100V cap with quality film bypass caps will remove all the phase shift and extends bandwidth to below 2 hz.

For greater bass energy, replace the 10,000 uf caps in a 545 with 22,000 uf caps, replace the 15,000 uf caps in the 555 with 30,000 uf.

The Adcom's are Nelson Pass designs like Hafler. The main difference is AC coupling in Haflers and mosfet output devices (which I really hate the sound of). I've also had recent Pass Labs amps in and they also failed the A/B test against the fixed up Adcoms. He also used mosfets in place of BJT's. Mosfets are non-linear devices that rely on heavy negative feedback to obtain a decent THD spec, but they still sound harsh to me. You will need better than NS-10's to hear the truth from these amps.

sorry to so blatantly pick your brain, but do you have a corresponding suggestion for the adcom 535?
And related, when I repaired the Adcom after I bought it, I noticed that it shares the PCB with the 545. Is it advisable to try slotting in the additional output devices to get the extra watts, or would it require more serious work than that?

I shouldnt even be asking since I haven't even finished the synth I started building last year, and my old Moog MG1 needs some work as well.

Jeff White · Post by **Jeff White** » Fri Jan 11, 2013 1:46 pm

Once again, Jim Williams hooks up everyone on this board with his tech knowledge. thanks so much for this advice!

Jeff

Jim Williams · Post by **Jim Williams** » Sat Jan 12, 2013 8:22 am

I have a 535 here too. Same design, different output transistors than the 545. No sense to upgrade those to higher current, the psu won't support them. Finding equivalent 2SA and 2SC devices will improve speed as the 545 does have extra air on top from using faster output devices.

Use a Nichicon 220 uf 100 V HE series cap for C109 and bypass it with some high end film caps. I used MIT, InfiniCap, Rel-Cap and some silver foil caps in my amps, all sound excellent.

calaverasgrandes · Post by **calaverasgrandes** » Sat Jan 12, 2013 9:52 am

nice, thanks. That is what I thought. As with tube power amps, changing things is constrained by the power supply. I was just hopping that adcom had used the same PS in both.
I may just keep it stock for a while longer. It still sounds immensely better than the SR power amp I had used before. Sure it had massive headroom, but it was like listening to everything through a neighbors wall.

Jim Williams · Post by **Jim Williams** » Sat Jan 12, 2013 11:48 am

I bought mine in 1988 new. Still works like a champ. It was a recommendation from Arnie Toshner, former monitor mixer with Brit Row (I toured with Stevie Wonder and he was the monitor AE).

He ran a store called Everything Audio in LA back then. It was a great place. He did have a gambling problem, once checking in to an Atlantic City hotel be blew a hundred bucks at the blackjack table while we were in line getting our room keys.

Turns out the demise of Everything Audio was caused during a Las Vegas weekend trip. He lost the store, so to speak!

Do make those cap swaps, the difference is like after your ears pop landing in a jet. Then the Adcoms slay competitors.

The Soundman Furry · Post by **The Soundman Furry** » Wed Jan 30, 2013 4:00 pm

I produced a record last year that was partially mixed by Bob Clearmountain and I asked him how he was powering his NS-10's. He told me he has used the same amp for years and shot them out against Brystons and the other popular choices. His amp of choice: Yamaha P-3200

I bought one myself and have been really happy with it. I think it was around $250 on ebay.

Sean Sullivan · Post by **Sean Sullivan** » Sat Mar 09, 2013 6:57 am

Hey Jim,

Where do you get the 30,000uF capacitors from?

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what is the best matched affordable power amp for NS 10s??

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