Hi Folks
I'm looking to replace the modules I have in my amp with something a bit more powerful, ideally without changing the power supply / toroidals. I'm looking for suggestions for modules or kits that fit the bill. My DIY capability is fair, and fading with my eyesight 🙂
I have an Aspen LifeForce amp for a dozen years or so, and love the sound. It's been driving an old pair of Monitor Audios Silver 9i's. But I was offered a pair of B&W 802 Series 3's at a good price and couldn't resist. But the Life Force modules don't really have a enough power, and (designer) Hugh reckons they probably can't handle the dip to lower impedance on the B&Ws.
So this is the ask, and I know there's probably only a limited number of options that fit the bill.
- 150 W module
- Work with a -50V / + 50V PSU
- Get enough power from 330VA / 33V
If you have any ideas that would work please let me know. I've seen a Marantz (clone / inspired by??) module on eBay that sounds good on paper, but I'm nervous it would go bad and damage the speakers.
thanks
Norman
I'm looking to replace the modules I have in my amp with something a bit more powerful, ideally without changing the power supply / toroidals. I'm looking for suggestions for modules or kits that fit the bill. My DIY capability is fair, and fading with my eyesight 🙂
I have an Aspen LifeForce amp for a dozen years or so, and love the sound. It's been driving an old pair of Monitor Audios Silver 9i's. But I was offered a pair of B&W 802 Series 3's at a good price and couldn't resist. But the Life Force modules don't really have a enough power, and (designer) Hugh reckons they probably can't handle the dip to lower impedance on the B&Ws.
So this is the ask, and I know there's probably only a limited number of options that fit the bill.
- 150 W module
- Work with a -50V / + 50V PSU
- Get enough power from 330VA / 33V
If you have any ideas that would work please let me know. I've seen a Marantz (clone / inspired by??) module on eBay that sounds good on paper, but I'm nervous it would go bad and damage the speakers.
thanks
Norman
I'm surprised as I had a AKSA 55 and Lifeforce 55 that handled a speaker that dipped down to 3.6 ohm (3.6 to 8.7 ohm envelope from 50Hz up) but without the roller coaster impedance and phase like the B&W which doesn't help. A lot of commercial amps of 100W plus would baulk at it but the Aspen amps handled them with ease.
Have a look at bi-amping with the Lifeforce doing the mid / tweeter and a larger amp doing the bass. I've heard a lot of systems using this configuration using PA amps for the bass and tubes or good SS amps for the mid /tweeter.
BTW, Troels did a xo upgrade on the B&W speaker.
B&W-802-Upgrade
Have a look at bi-amping with the Lifeforce doing the mid / tweeter and a larger amp doing the bass. I've heard a lot of systems using this configuration using PA amps for the bass and tubes or good SS amps for the mid /tweeter.
BTW, Troels did a xo upgrade on the B&W speaker.
B&W-802-Upgrade
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Your transformer & heat sinks are sized for the power level your amp will put out now. Number of output transistor pairs is only 1 element of the 3 required for a higher power amp. 330 VA transformer is 2/3 what my ST120 amp has, 60 w/ch.
You are lucky to live in North America. The best bargain in heat sinks and power transformers is surplus PA amps from the bar band market. The ones with transformers from the late 80's and 90's are particularly cheap because bands that set up and tear down every night don't want to carry the weight. They want switcher supplies and often, class D instead of AB.
On craigslist or ebay you can often find 400 to 800 W PA amps that work badly for $200. In summer you can often find ones that are sold for parts or repair at $20-50 plus freight. In winter they are getting scarce. Most of these have built in speaker protection against DC.
I picked up a Peavey PV-4c for $28 including freight, and put $80 in parts in it (OT's, rail caps, temp sensor) . 210 w/ch 4 ohms. It has speaker protection crowbar. I use mine every night in my TV room on speakers rated 13 W max.
Peavey CS800 often run $50-200 and the X & S revisions have speaker disconnect relay protection. X & S get HD down to .03% as is. A B C revisions are hissy but the input op amp can be upgraded from 741 or 4558 to something quieter with probably much better HD result too. I pick up a CS800s with a bar band setup for about $100, that had blown input resistors (75 w amp speaker cable plugged in input), a dried up cap in the switcher supply that took out a $2 NTCR, and a bad solder joint dropping one channel sometimes.
Other bar band war horses with less parts support are QSC, Crown, Yamaha. You'll get no schematics from Behringer, don't waste your time on anything but a new one.
If you find the fan noise annoying in these, tweak the fan control for nothing at low temperatures, and adjust the OT idle bias current to limit lower power heating. No bias control pots in these, you change resistor values with a soldering iron.
Happy shopping, and perhaps rebuilding.
You are lucky to live in North America. The best bargain in heat sinks and power transformers is surplus PA amps from the bar band market. The ones with transformers from the late 80's and 90's are particularly cheap because bands that set up and tear down every night don't want to carry the weight. They want switcher supplies and often, class D instead of AB.
On craigslist or ebay you can often find 400 to 800 W PA amps that work badly for $200. In summer you can often find ones that are sold for parts or repair at $20-50 plus freight. In winter they are getting scarce. Most of these have built in speaker protection against DC.
I picked up a Peavey PV-4c for $28 including freight, and put $80 in parts in it (OT's, rail caps, temp sensor) . 210 w/ch 4 ohms. It has speaker protection crowbar. I use mine every night in my TV room on speakers rated 13 W max.
Peavey CS800 often run $50-200 and the X & S revisions have speaker disconnect relay protection. X & S get HD down to .03% as is. A B C revisions are hissy but the input op amp can be upgraded from 741 or 4558 to something quieter with probably much better HD result too. I pick up a CS800s with a bar band setup for about $100, that had blown input resistors (75 w amp speaker cable plugged in input), a dried up cap in the switcher supply that took out a $2 NTCR, and a bad solder joint dropping one channel sometimes.
Other bar band war horses with less parts support are QSC, Crown, Yamaha. You'll get no schematics from Behringer, don't waste your time on anything but a new one.
If you find the fan noise annoying in these, tweak the fan control for nothing at low temperatures, and adjust the OT idle bias current to limit lower power heating. No bias control pots in these, you change resistor values with a soldering iron.
Happy shopping, and perhaps rebuilding.
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Thanks rabbitz, that's an inspired suggestion on bi-amping. Never occurred to me to t=do that. I actually have an old Denon AVR-5600 I've been using with the B&Ws until I figured out what to do. It ain't graceful but it does have 140w per channel. I've now biamped it with the LF100 and the sound is stirring. I've never had the pleasure of this before, in my own house at least.
The upgraded XO design from Troels looking pretty straightforward. Might be a winter project for me.
Indianjo, that's excellent info on a good source for PA amps. Could work very well with this combination. I'll key an eye out on the used market.
thank you both
The upgraded XO design from Troels looking pretty straightforward. Might be a winter project for me.
Indianjo, that's excellent info on a good source for PA amps. Could work very well with this combination. I'll key an eye out on the used market.
thank you both