Needs a basic, free synth with low CPU usage.

[Debutante]

GTG Synths are exactly what you're looking for.

http://www.gtgsynths.com/plugins.htm

[BBFG#]

Give these a try, especially STS26/STS33/Alphatron

http://www.hgf-synthesizer.com/nfg---pro-vsti-free.html

That page has a lot of wild freebies in 32bit.

This one too:

http://www.gtgsynths.com/plugins.htm

My favorites are the JP7A and K1.3 but quite a few good for free ones there.

And don't forget to check out the HG Fortune synths too.

[crimsonwarlock]

Also whoever suggested Firebird 2, it doesn't show up in reaper for some reason

Works without problems in Reaper 32bit here

Also check out Junglist, PolyIblit and Bojo Impulse.

Lastly, hit the link in my signature for more suggestions

[Halma]

How could I forget it?

HYDi (but it needs a bit more CPU)...

...

Great synth but unfortunately not poly.

Firebird2 runs fine here in Reaper and is a really great choice if you are looking for a low CPU synth with all kind of waveforms. Mostly the first STA ones without any further modulation or some PWM if you wanna keep it simple. Plus the choices of filters is absolutely gorgeous. So many different sounding filters (lots of character low pass ones) and wiered things. The inbuilt ARP (incl one chord and one gate function) and the LFO (which also comes with a lot of often overlooked "special" rhythmic patterns which can be host synced) can do some neat things. Plus it has unison and a real great lowend. The only knob I mostly never use is the distortion one in the DCF section. And the envelope timing could be a tad longer but otherwise a true powerhorse for poly and mono sounds.

Regards
Sebastian

[Ingonator]

Tactile Sounds Substance:
http://tactilesounds.blogspot.de/p/ts-substance.html


Ingo

[yessongs]

Prodigious
http://www.pluginboutique.com/product/4-Synth/470-Prodigious

Poly 2106
http://www.pluginboutique.com/product/4-Synth/471-Poly-2106

Triangle II
http://www.pluginboutique.com/product/4-Synth/661-Triangle-II

Minimoque VA
http://www.pluginboutique.com/product/4-Synth/151-Minimogue-VA

Antitranspirant
http://www.pluginboutique.com/product/4-Synth/288-Anti-Transpirant-Mono-Stepper

Alchemy Player
http://www.pluginboutique.com/product/4-Synth/599-Alchemy-Player

Proteus VX
http://www.creative.com/emu/proteusvx/

SQ8L
http://www.buchty.net/ensoniq/

PG8X
https://sites.google.com/site/mlvst0/

Uhe: Zebralette, Tyrell, Triple Cheese, Podolski
http://www.u-he.com/cms/

Voyager
http://www.vst4free.com/free_vst.php?id=383

Oatmeal
http://bicycle-for-slugs.org/

Synth 1
https://sites.google.com/site/synth1vst/

fullbucket has a lot of free synths that rock
http://www.fullbucket.de/music/vst.html

Dune BE
http://www.maclife.de/beat/news/kostenloser-megasynth-synapse-audio-dune-le link may have changed to something else not sure how to snag this gem so anyone else feel free to share with us how it is possible

Sonigen Modular
http://www.sonigen.com/

OBXD latest version is bad ass thread link below
http://www.kvraudio.com/forum/viewtopic.php?f=1&t=387568&start=900

Elektro studio mainly for the tron and the ODSAY
http://www.vst4free.com/index.php?dev=Elektrostudio

Firebird http://www.tone2.com/html/firebird_vsti_vst_synthesizer_1.html

TAL synths:
http://kunz.corrupt.ch/Products

Charlatan
http://www.blaukraut.info/

Mausynth
http://rinki.net/pekka/mausynth/

Alieno
http://www.blank-media.it/acrobatics/

A synth
http://antti.smartelectronix.com/

String Theory
http://www.kvraudio.com/product/string_theory_by_ugo

Soha Sonata
http://www.sohasound.com/sonata.php

AAS Swatches
https://www.applied-acoustics.com/swatches/overview/

Istvan Kaldor Collection especially for maestro and dirtbag
http://www.vstplanet.com/Instruments/VST_Synthesizers13.htm

Antopya
http://ldaysynths.blogspot.com/2009/12/antopya-vsti.html

DEMOS worth getting because you can play with them a lot and it won't sound bad at all.
http://www.amaranthaudio.com/products/cycle/
http://www.memorymoon.com/
Diva Zebra ACE see Uhe above

Coming soon synthmaster FREE version with 150 presets
http://www.kvraudio.com/forum/viewtopic.php?f=1&t=400325

[Chris-S]

Don't pass up synth1 just because it looks complicated and ugly.

You can adjust the colors. I've set mine to red like the clavia nord lead (on which synth1 is based on).

[BBFG#]

Prodigious
http://www.pluginboutique.com/product/4-Synth/470-Prodigious
Poly 2106
http://www.pluginboutique.com/product/4-Synth/471-Poly-2106
Triangle II
http://www.pluginboutique.com/product/4-Synth/661-Triangle-II
Minimoque VA
http://www.pluginboutique.com/product/4-Synth/151-Minimogue-VA
Antitranspirant
http://www.pluginboutique.com/product/4-Synth/288-Anti-Transpirant-Mono-Stepper
Alchemy Player
http://www.pluginboutique.com/product/4-Synth/599-Alchemy-Player
Proteus VX
http://www.creative.com/emu/proteusvx/
SQ8L
http://www.buchty.net/ensoniq/
PG8X
https://sites.google.com/site/mlvst0/
Uhe: Zebralette, Tyrell, Triple Cheese, Podolski
http://www.u-he.com/cms/
Voyager
http://www.vst4free.com/free_vst.php?id=383
Oatmeal
http://bicycle-for-slugs.org/
Synth 1
https://sites.google.com/site/synth1vst/
fullbucket has a lot of free synths that rock
http://www.fullbucket.de/music/vst.html
Dune BE
http://www.maclife.de/beat/news/kostenloser-megasynth-synapse-audio-dune-le link may have changed to something else not sure how to snag this gem so anyone else feel free to share with us how it is possible
Sonigen Modular
http://www.sonigen.com/
OBXD latest version is bad ass thread link below
http://www.kvraudio.com/forum/viewtopic.php?f=1&t=387568&start=900
Elektro studio mainly for the tron and the ODSAY
http://www.vst4free.com/index.php?dev=Elektrostudio
Firebird http://www.tone2.com/html/firebird_vsti_vst_synthesizer_1.html
TAL synths:
http://kunz.corrupt.ch/Products
Charlatan
http://www.blaukraut.info/
Mausynth
http://rinki.net/pekka/mausynth/
Alieno
http://www.blank-media.it/acrobatics/
A synth
http://antti.smartelectronix.com/
String Theory
http://www.kvraudio.com/product/string_theory_by_ugo
Soha Sonata
http://www.sohasound.com/sonata.php
AAS Swatches
https://www.applied-acoustics.com/swatches/overview/
Istvan Kaldor Collection especially for maestro and dirtbag
http://www.vstplanet.com/Instruments/VST_Synthesizers13.htm
Antopya
http://ldaysynths.blogspot.com/2009/12/antopya-vsti.html

DEMOS worth getting because you can play with them a lot and it won't sound bad at all.
http://www.amaranthaudio.com/products/cycle/
http://www.memorymoon.com/
Diva Zebra ACE see Uhe above
Coming soon synthmaster FREE version with 150 presets
http://www.kvraudio.com/forum/viewtopic.php?f=1&t=400325

You forgot Image Line's Autogun:

http://www.image-line.com/plugins/Synths/Autogun/

With literally "4,294,967,296 amazing presets to explore".

[Tricky-Loops]

http://www.image-line.com/plugins/Synths/Autogun/

With literally "4,294,967,296 amazing presets to explore".

I'm still doubting their number of presets. I tried it several times - via the Randomize button - and after ca. 100 presets, (some of) the same presets came again...

[BBFG#]

http://www.image-line.com/plugins/Synths/Autogun/

With literally "4,294,967,296 amazing presets to explore".

I'm still doubting their number of presets. I tried it several times - via the Randomize button - and after ca. 100 presets, (some of) the same presets came again...

I think many are very subtle differences and agree, too close to really call them different.
Its asset seems to be its worst flaw to me though.
The lack of a real browser or anyway to reasonably find a re-usable way to find them (short of the copy/paste or add to favorites) makes it annoying to me.

Still, it is worth a mention and it does have fantastic sounds.

[MachFront]

FreeAlpha seems to fit your demands.

[yessongs]

http://www.image-line.com/plugins/Synths/Autogun/

With literally "4,294,967,296 amazing presets to explore".

I'm still doubting their number of presets. I tried it several times - via the Randomize button - and after ca. 100 presets, (some of) the same presets came again...

I think many are very subtle differences and agree, too close to really call them different.
Its asset seems to be its worst flaw to me though.
The lack of a real browser or anyway to reasonably find a re-usable way to find them (short of the copy/paste or add to favorites) makes it annoying to me.

Still, it is worth a mention and it does have fantastic sounds.

I actually thought hard about that one then I thought some more and decided not to put it on the list. You have to draw the line somewhere I mean Augur is another I left off that I thought hard about including as well.

[aciddose]

POST EVERYTHING THREAD!

[layzer]

FreeAlpha seems to fit your demands.

+1
a snappy filter on that puppy

[spacedad]

sheesh theirs some odd suggestions in this thread!
seems like would be good.....
http://www.xoxos.net/vst/vst.html#synthesizers

Clearsynth:
A simple 2-oscillator synthesizer for students.
The first 42 patches progress through the features. The patch names should acquaint the user with a basic knowledge of subtractive synthesis.