Siege frigates have light armor. Therefore, the best ships to use to take them out would be either fighters, or (if your enemy has a dangerous amount of flak as well) heavy cruisers.

Another option would be to build a starbase on one of your worlds - in addition to being able to quickly destroy large numbers of enemy frigates, you can also get an upgrade which prevents loss of planet ownership due to bombardment. The AI should keep bombing your world anyway though - with your starbase making quick work of the enemy fleet, your other ships can take out the siege frigates.

Also, is your game updated to the most current version? (1.33 Trinity/Diplomacy) I heard that siege frigate spam was a more common tactic before, but in my (few) recent games against AI I've rarely seen them build more than two siege frigates at a time. A somewhat recent patch changed AI build behavior so that they would only build a few siege frigates at once.

Starbases are strong against Disciples, but so are long range frigates: the LRM, the Assailant, or the Illuminator. So in addition to building a starbase you could build a fleet of mainly LRF. LRF are also relatively good against enemy capital ships.

Edit: Oh, you're playing Vanilla, lol. Well OK, then if the enemy has mainly siege frigates, light frigates, and capital ships, then your best bet would be to build heavy cruisers and long range frigates.

A strategically cheap but effective strategy is to build a few turrets, which do incredible amounts of damage to light frigates and capital ships. If you do that and can lure the enemy fleet into their range, the enemy fleet will very quickly go down.

Yeah if you have version 1.0 of the original Sins siege frigate spamming is a very dangerous tactic. Its really quite difficult to counter, especially early on before you can get any sort of cruisers online. You really should contact support or do whatever you can to update, even without the expansions the game has become much better with the updates.

I probebly will, I like the idea of Comp stop. Well, I am slowly winning. I killed 2 of their caps, maybe 3. They are just running back and forth between 2 worlds, so it will take a bit.

Eventually the AI will buy capitalship levels, maybe even in version 1.0, but they need to have a good economy going to do that (and thus will probably only happen at the high AI levels).

Also FYI having a lot of capitalships is often not a good strategy. Capitalships are really needed because of their powerful abilities, but for their cost and fleet supply their firepower is not very good. As you'll mainly want firepower when dealing with siege frigates, focusing on combat frigates is a much better idea.

This. As a rule of thumb, having more than 2 or 3 capital ships is rarely a good idea, except in the very late game.

ps. Prevoke Histeria is Epic! Kills almost half the healt of the enemy's 6000hp Homeworld!

I didn't. The Revelation was my 2nd. I got it for planet bobardment and fleet killing. A mothership (now in my defence fleets to protect against invatsion from the star) was my first. My 3rd was a radience to assist my Revelation, my 4th was a carrier to provide strike craft support, my 5th was a mothership to colonize destroyed worlds, and to help heal shields.

Also, I think you might call me crazy when I made a 6th (Rapture) for my defence fleets (Voice's homeworld). And a 7th (same as 1st mothership). But when I saw an average of 2 vasari seige caps, and a revelation battle cruiser in the star, I knew I needed a strong defence in that area. I also needed a quick defence for Voice's captured HW, as they were very frequently attacking.

Now I need to capture a planet to resupply my main fleet with frigates. (reminder I lost all LF, Guardians, and almost all of my LRF.)

I had plenty of money, but I think you mis understoon why I put defences near the star. I was afraid that they would launch an invasion with the capital ships, or later the massive seige frigate fleets prowling about the gravity well. I saw a lot of worlds get invaded by those fleets from the star.

Now, I am resupplying my fleet with 20 lf, 15 Hc (I managed to get them to do 30 dps each) and about 6 LRF (Only 6 because I ran out of $, I will be leaving with much more LRF.

If you happened to have a spare capital ship factory already built there and no frigate factories, go for it. But as you know, frigates are generally much better if you're trying for firepower.

Actually, I just had an idea which might work to mitigate AI-controlled siege frigate spam. It works on the militia, at least... if you start building a turret in the range of the siege frigates, often they will scatter and attempt to regroup in some other section near the planet so they can bomb from a safe distance.

If this behavior happens in whichever ancient version of Sins you have, you can buy yourself a very long amount of time this way (allowing you to build frigates to increase your firepower to destroy the siege frigate swarm). Start building a turret in range of the siege frigates, then stop construction, move the constructor close to the next area the siege frigate swarm moved to, start construction on another turret (but don't finish it), repeat. Scrap your unbuilt turrets, you won't be losing much money at all from the scuttle costs.

Now, this strategy requires extraordinary micromanagement and is a blatant exploitation of the dumb AI, but it might work. Just make sure the siege frigates' weapons don't kill your constructor.

Well that works.

To be honest I'm not all that sure about what siege frigates are like in your version, apparently they used to be extremely overpowered...

While that many siege frigates can still kill worlds extremely quickly, they're nowhere near as durable as to stand up to a decent-sized fleet plus defenses...

When I was talking about the overpowered seige frigates, I was talking about version 1.0, now I am on the latest version. Strikecraft look weird, and I also accidently spent $ on bounty.