I need to correct the jumper comment. What Andrew Sparks recommended was to jumper pin 2 to pin 7 using a 3.3M resistor and to do the same between pins 3 and 7.
Forte Model 2 pre-amp
- Thread starter Tedrick
- Start date
Looks like it might be another AKer.
The price is what I seen completed listings go for but this one is also worked on.
I don't normally say what I paid for something but I'll brag a bit. It was in my local record store and never worked on, but for $40.00 I didn't think I could go wrong even untested. It wasn't till I got home and found out it had an adjustable phono stage. In the first use it had no noise in switches and sounded good. I'll end up using it somewhere but not in my maine system as I like a remote there.
I think even if you get it and try it but feel what you have is better, it still would be a nice stand alone phono stage.
BTW, I think the biggest upgrade you could make to the Forte would be to replace the outboard power supply with a regulated supply. The power supply is completely unregulated, which is a bit surprising given its pedigree/price.
What power supply would you recommend that is regulated? I do notice that this pre responds well to good power conditioning, but I'd be interested in improving it further.
It depends on the voltage being provided by the current supply. You need a power supply that matches the voltage of the current supply and meets or exceeds the current rating. Matching the voltage is very important in this case because the preamp doesn't have any onboard regulation.
If you look at the picture of your power supply on the previous page, you'll see that the current power supply has a transformer providing 18v-0-18v at 0.16 amps. To the left are 4 diodes, there's a resistor and two 2200uf/35v caps. Below the 2 caps, the cable connecting the power supply to the preamp is connected to the board by 3 wires. One is carrying the positive rail, one is the negative rail and one is the ground. You'd have to measure each to figure out the voltage needed, but it's probably around 15 volts.
You're probably not going to be able to use an off-the-shelf solution.
You can get a regulated board on ebay (like this one; assuming the voltage output is correct):
https://www.ebay.com/itm/Ultra-low-...215744?hash=item2ee5f02340:g:2mIAAOSwLqFV8pxF
And a toroid like the one here:
https://www.parts-express.com/avel-lindberg-y236503-160va-22v-22v-toroidal-transformer--122-615
And a case:
https://www.ebay.com/itm/Full-Alumi...461917?hash=item2134d78b5d:g:RuQAAOSw0e9Uv1AT
So, that's $200, if you're handy with such things or you can get someone to put it together for free. The question is whether the juice is worth the squeeze.
If you look at the picture of your power supply on the previous page, you'll see that the current power supply has a transformer providing 18v-0-18v at 0.16 amps. To the left are 4 diodes, there's a resistor and two 2200uf/35v caps. Below the 2 caps, the cable connecting the power supply to the preamp is connected to the board by 3 wires. One is carrying the positive rail, one is the negative rail and one is the ground. You'd have to measure each to figure out the voltage needed, but it's probably around 15 volts.
You're probably not going to be able to use an off-the-shelf solution.
You can get a regulated board on ebay (like this one; assuming the voltage output is correct):
https://www.ebay.com/itm/Ultra-low-...215744?hash=item2ee5f02340:g:2mIAAOSwLqFV8pxF
And a toroid like the one here:
https://www.parts-express.com/avel-lindberg-y236503-160va-22v-22v-toroidal-transformer--122-615
And a case:
https://www.ebay.com/itm/Full-Alumi...461917?hash=item2134d78b5d:g:RuQAAOSw0e9Uv1AT
So, that's $200, if you're handy with such things or you can get someone to put it together for free. The question is whether the juice is worth the squeeze.
Thanks for all of the information and input. I can measure the actual voltages as you suggested and proceed from there. I imagine that I could figure out how to put it all together. I do notice that the Forte 2 sounds better when pugged in to my RGPC 400. I don't know if that is crazy or not, but it does seem to make a difference.
So, I measured what I could measure. The Voltages (DC) were +22V and - 22V being sent to the pre-amp unit from the power supply. My meter only has an Amperage measure down to 10 AMPS .... so it didn't really measure .. I got roughly between 0.1 and 0.0 on the meter I have - of which I don't know what to make of it. Is the Amperage maybe below 0.1Amps? Something on the blue box in the power supply mentions .036 Amps - would that make sense?
