A wave editor would be a better way to process a conversion. So far the best I've used was Sony Sound Forge for this. Wave Labs noise reduction isn't very good. Sonar is not a wave editor and the last software I would use for this. 
You could try Audacity which is free and it will share your Sonar plug ins. 
Also Try different Dolby settings. Dolby has an effect on hi frequency content and some decks had up to 3 different modes. 
Then There was that other one?? DBX?? can't remeber that's 20 years ago. 

Don't know how much help, but I just remembered my first interface UA-1G has RCA jacks, may make it easier to get tape into PC anyway. Just a suggestion.

Free from Digital Fish Phones - Spitfish (http://www.digitalfishpho...?item=2&subItem=5) is a really good de-esser, better than some that cost me quite a few dollars, might help with the sibilance.

For general clean-up, though I haven't used it, the also free iZotope Vinyl (http://www.izotope.com/products/audio/vinyl/) may help with other cleanups.

Hope those help & good luck.

Best,
guitardood

If you know if the original recordings were made with dolby B or C, then playing back the tracks with the same dolby would be a great way to do noise reduction.

Also, to keep tape hiss at the lowest, hit your inputs with as much volume as you can (without clipping). You want a good signal-to-noise ratio. I have been doing a lot of cassette to Sonar conversions lately. The first thing I do is put Sonitus EQ in the FX bin. Grab band #6 (the highest freq band) and drag it down 4-5 db (this is approximate; it all depends on the tape). Usually that will help a lot with high frequency HISSSSS. Good luck!

You might want to consider demoing iZotope RX2. It costs a bit but provides a number of useful tools. I have it and it works well cleaning up background noise.

http://izotope.com/products/audio/rx/

gs

Then There was that other one?? DBX?? can't remeber that's 20 years ago. 

 DBX was wonderful back in the day... You'd know it if you played one without the decoder - way compressed and screechy...

As GSWITZ says, experimenting with Dolby B or C on playback is worth the time, but I've found HarBal to be brilliant to quickly knock the basic sound of old recordings into a better balanced sound - then add other processing as required.

guitardood


Free from Digital Fish Phones - Spitfish (http://www.digitalfishpho...?item=2&subItem=5) is a really good de-esser, better than some that cost me quite a few dollars, might help with the sibilance.

For general clean-up, though I haven't used it, the also free iZotope Vinyl (http://www.izotope.com/products/audio/vinyl/) may help with other cleanups.

Hope those help & good luck.

Best,
guitardood

Do you know if there's a 64bit Spitfish yet? Last time I looked it was still only 32bit

Bristol_Jonesey

guitardood


Free from Digital Fish Phones - Spitfish (http://www.digitalfishpho...?item=2&subItem=5) is a really good de-esser, better than some that cost me quite a few dollars, might help with the sibilance.

For general clean-up, though I haven't used it, the also free iZotope Vinyl (http://www.izotope.com/products/audio/vinyl/) may help with other cleanups.

Hope those help & good luck.

Best,
guitardood

Do you know if there's a 64bit Spitfish yet? Last time I looked it was still only 32bit

AFAIK, the developer is not going to do any updating including recompiling for 64-bit.  Shame since they are some of the best plugs I've got in my arsenal even through bit-bridge, especially SpitFish & FloorFish.


Best,
guitardood