The club have pushed ahead with their transfer plans this summer, bringing in the ex-Villa striker and the Chelsea youngster.
Archer signed on Friday and came on in the second half of a 1-0 loss to Newcastle United.
Speaking to the Daily Echo, Martin said: "They both had interest from other clubs and I'm really pleased they've chosen us - and Chelsea for choosing us to help develop Lesley.
"I am really impressed with them both as young men. I met them both and discussed things at length. I think they fit in really well.
"They give us something we don't have. Lesley, in his position real power, real athleticism. Cameron is really sharp, really quick and an absolute goal threat.
"I think they're both going to be brilliant signings and I'm really, really pleased to get them done."