Foster WF-100K plate amps

[planet10]

This thread split from here 150hz crossover

Originally posted by 901Fixer
I done ordered me two of them Foster WF-100K plate amps, thanks for the tip Dave.

dave

[serenechaos]

Have you heard "them Foster WF-100K plate amps?"
Is sound quality decent?
I don't expect the very best for that price, and did notice quite a roll-off below 30Hz, but they are very reaonably priced...
r

[planet10]

Originally posted by serenechaos
Have you heard "them Foster WF-100K plate amps?"
Is sound quality decent?
I don't expect the very best for that price, and did notice quite a roll-off below 30Hz, but they are very reaonably priced...
r

There is lots of info for tweaking them... the LF roll-off is a filter that can be removed or changed. I'd guess these are leftovers from a multi-thosand $ NHT floorstander with integral powered woofer.

dave

[serenechaos]

didn't find lotsa tweaking info, just the lynx on the for sale page, (which did include the schematic; can go from there).

Just wondering about the sound quality of the base amp-- again, not expecting too much in components for the price...

Guess the only way to find out is to "buy & try;" so I ordered four.
Bridge a pair for each side to feed a pair of tapped horns.

[planet10]

Originally posted by serenechaos
so I ordered four.

We should start a thread on hacking these...

1/ removal of elco caps in the signal path
2/ swap ICs
3/ bypass sections that are not useful

dave

[doug20]

Originally posted by serenechaos
Have you heard "them Foster WF-100K plate amps?"
Is sound quality decent?
I don't expect the very best for that price, and did notice quite a roll-off below 30Hz, but they are very reaonably priced...
r

These are from high quality speakers VT-3, Jack has been selling NHT products extremely cheap for awhile too bad nothing is left on his site.

I picked up the VR-3 kits for $150 each, 10-083 woofers for $30 each and 4 of those amps talked about.

You have to realize their price does not indicate performance, they are left over from NHT's bankruptcy....all though lots of the products on Jacks site when back to NHT or similar so someone is doing something with the rest of the inventory.

[doug20]

Originally posted by planet10


We should start a thread on hacking these...

1/ removal of elco caps in the signal path
2/ swap ICs
3/ bypass sections that are not useful

dave

That would be great I own 4 of the amps myself along with the 4 083 10" woofers that will work with them.

[serenechaos]

Originally posted by planet10


We should start a thread on hacking these...

1/ removal of elco caps in the signal path
2/ swap ICs
3/ bypass sections that are not useful

dave

starting a thread sounds like a good idea, or moving this hi-jack--
do you know a moderator?

2) not up on ICs, i've only built tube amps before...
what's recommended?

[901Fixer]

Originally posted by serenechaos
Have you heard "them Foster WF-100K plate amps?"
Is sound quality decent?
I don't expect the very best for that price, and did notice quite a roll-off below 30Hz, but they are very reaonably priced...
r

My decision was based on a couple of factors.
-For one, compared to my other options for a woofer amp with 80w into 8ohms with all of the needed selectable options, this was much less expensive be it either a plate amp or rack mount.

-More importantly, if they are good enough for Dave to buy 10 of they gotta be good enough for me.

I mostly responded to show the price I paid total delivered for a comparison to crossing over passively. My woofers are 8ohm Selenium 15PW3 ProAudio style and will roll off before 30hz anyway with an Fs of 39hz and F3 of 44hz in the enclosure I'm building.

[planet10]

The bit on this amp from <http://home.comcast.net/~jhidley/>

oster subwoofer plate amplifier. 115W into 4ohms, 80W into 8ohms. 4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB. See response curves linked below. A drawing of the amplifier and schematic are both linked below. Two of these amplifiers can be bridged together to produce 220W into 8ohms. See the FAQ below for details of bridging and filter modifications.