Forte model 3 with SDA
dankHugzNY
Posts: 29
in Speakers
I have a chance to buy a forte model 3 and I understand that it's dual mono but am curious if it's also common ground for use with SDA. Searching online hasn't revealed a definitive answer, I posted the question on a classic audio fb group and only received private messages telling me it won't work and asking for the sellers info, lol. Can anyone help solve this mystery?
Comments
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Dual mono would mean it is not common ground. You may be able to contact the maker and see if you can strap the grounds together or you can go with a dreadnaught.Just a dude doing dude-ly things
"Temptation is the manifestation of desire which equals necessity." - Mikey081057
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"Audiophiles are the male equivalent of cat ladies." - Audiokarma Member -
True dual mono means it's non-common ground as each channel shares nothing, especially the transformers, but some dual mono amps cheat by sharing a single transformer and therefore may actually share the ground. Looking at the guts of the amp in question I see a single transformer, so the only way for you to know is test the negative outputs.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
The pic I was able to find show's stacked dual transformers. However it appears the negative speaker output connections are tied to power supply star ground. It does not have a bridged/ balanced output stage so could be used with SDA's. I could not find a schematic and could not from the pic tell if there are resistors isolating each channels ground individually from chassis ground. If there were simply strapping the two negative posts together would make it common ground.
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This is the pic I found.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
That might be a pic of the model 1? Heres the one I found Jesse. http://audiokarma.org/forums/index.php?media/forte-model-3.1016/
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The pic I was able to find show's stacked dual transformers. However it appears the negative speaker output connections are tied to power supply star ground. It does not have a bridged/ balanced output stage so could be used with SDA's. I could not find a schematic and could not from the pic tell if there are resistors isolating each channels ground individually from chassis ground. If there were simply strapping the two negative posts together would make it common ground.
Thank you.
Doesn't the interconnect cable essentially also tie the negative connections together?
Yah and from the pics I've seen it looks like two transformers stacked. The amp is 2.5 hours away but is only $250 so it's a pretty good deal, no?
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dankHugzNY wrote: »The pic I was able to find show's stacked dual transformers. However it appears the negative speaker output connections are tied to power supply star ground. It does not have a bridged/ balanced output stage so could be used with SDA's. I could not find a schematic and could not from the pic tell if there are resistors isolating each channels ground individually from chassis ground. If there were simply strapping the two negative posts together would make it common ground.
Thank you.
Doesn't the interconnect cable essentially also tie the negative connections together?
Yah and from the pics I've seen it looks like two transformers stacked. The amp is 2.5 hours away but is only $250 so it's a pretty good deal, no?
I'm going to leave this to the more seasoned people who can explain it better than I can. Curious though what SDA models do you have and is the interconnect cable pin/blade or blade/blade?Just a dude doing dude-ly things
"Temptation is the manifestation of desire which equals necessity." - Mikey081057
" I have always had a champange taste with a beer budget" - Rick88
"Just because the thread is getting views don't mean much .. I like a good train wreck doesn't mean i want to be in one..." - pitdogg2
"Those that don't know, don't know that they don't know." - heiney9
"Audiophiles are the male equivalent of cat ladies." - Audiokarma Member -
That might be a pic of the model 1? Heres the one I found Jesse. http://audiokarma.org/forums/index.php?media/forte-model-3.1016/
Here's a link to the one in my pic, definitely a model 3. Scroll through the pics.
http://www.hifishock.org/gallery/electronics/forte-audio/power-amplifier/model-3-0-forte-audio/Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Yeah and that one looks like a single transformer but the angle might be deceiving. I really wanna drive 150 miles to get it but only if it'll be okay with the SDAs!
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Call their CS and ask...
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Interesting. Maybe the earlier versions had a single larger transformer? The transformer in that pic has separate secondary windings ,each one feeding a separate bridge rectifier for each channel.That might be a pic of the model 1? Heres the one I found Jesse. http://audiokarma.org/forums/index.php?media/forte-model-3.1016/
Here's a link to the one in my pic, definitely a model 3. Scroll through the pics.
http://www.hifishock.org/gallery/electronics/forte-audio/power-amplifier/model-3-0-forte-audio/
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The interconnect completes the circuit between the dimensional drivers so they will reproduce the difference signal.dankHugzNY wrote: »
Thank you.
Doesn't the interconnect cable essentially also tie the negative connections together?
Yah and from the pics I've seen it looks like two transformers stacked. The amp is 2.5 hours away but is only $250 so it's a pretty good deal, no?
Strapping the negative terminals on the amp assures it is common ground.
Given it's origin and assuming it's working fine then it seems like a reasonable deal to me.
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Call their CS and ask...
The designer is still going strong but the Forte company has been defunct for a couple of decades. -
So what are ya's sayin Fred the ring a dingy thingy may not work
why not test with a multi meter? Wouldn't that give you your answer? -
Certainly that would confirm it. In the pic I linked to it appears the negative output (black)wires from each channel are tied to the power supply ground bus. If so that would make it common ground.why not test with a multi meter? Wouldn't that give you your answer?
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Did Threshold buy Forte? Maybe their CS can help? -
Forte was concieved as an offshoot of Threshold intended to develop and market lower cost(compared to Threshold) high performance products. The original founders of Threshold have long since moved on and the Forte brand was discontinued. There may still be someone on staff at the new Threshold that has knowledge of the decades old products. Nelson Pass the designer frequents Pass Labs forum at DIY Audio and would give you a definitive answer if you can track him down. However after looking at several pic's of the model 3's interior the Forte is common ground.
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Do you guys think this amp will be okay in other ways assuming it's common ground? I couldn't find much info on it. I did read that someone was using it to drive low impedance speakers with no problem.
I'm just trying to get a high current amp and it's either this or a NAD 2600A -
I got it. There is one transformer.
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Use your DVM to test the ohms reading at the negative outputs with the amp unplugged.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I tested it, It's common ground. Thank you for all of your input. I also had found a thread online where Nelson Pass said he thought the output was common ground. When I read that I felt secure in taking the 150mile trip.
This amp has opened the soundstage up incredibly. Amazing. I need bigger polks now, I only have SDA2A. -
Congrats! Enjoy your amp. Apparently at some point in it's production life the model 3's went from using a single transformer with multiple secondaries to two separate transformers.
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I think the one with two transformers was a modified one, in my research I came across someone talking about a modded one.
