Just some FWIW hop U from out from under my pencil.
I did the PM version with 2# Vienna, 0.5# Crystal and 5# DME. I used 2.0 ozs of 5.9% Cascade. I turned off the heat and added all the DME with 15 minutes left in the boil. What I did was pause the clock, add the DME off the heat, return to heat, return to boil, restart clock, add 15 minute hops, continue. I ass/u/me zero additional hop U during the pause to dissolve.
With a 3 gallon boil and a 5.5gal ready to pitch OG of 1.050, I think I got 31 HBUs. I had to fudge alittle since I started the boil at 1.020. I would have expected 34.8 just off the 5.9% compared to EdWorts original 6.6%, obviously my U is lower.
Using one of the hop U calculators I concluded I would need 14.8 HBUs of hops to match the 39IBU edWort describes for the Ag version page one this thread.
EDIT: It occurs to me overnight matching IBU to IBU is not quite the whole picture. I feel like a big part of what makes an APA an APA is the balance between bitter- flavor - aroma. Judging by the uniformly positive reviews here EdWort struck a good balance. I am going to do the math twice more, once to see how many IBUs the AG version should produce at 60-30-15-5, and then go back and jiggle the hop rates for PM late DME version at the top of this post.
Using the Tinseth method from realbeer link:
http://realbeer.com/hops/FAQ.html#units
I caluclate EdWort is getting 20.8 IBUs out of the (60), 7.9 (30), 2.6 (15) and 1.4 (5), ass/u/me his SG is constant at 1.050 on 5.5 gallons. So ballpark, on the
Tinseth table EdWort is getting 32.7IBU into his 5.5 gal ferment.
Using the same Tinseth chart for U and the *ME schedule from above, ...<standyby>
I think it will take 19.1 HBUs for a PM brewer to match the AG hop balance.
7.2 HBU @ 60 min will put 37.4 IBUs in the three gal boil
6.4 HBU @ 30 min = 14.2 IBUs in the boil
2.6 HBU @15 min = 4.7 IBU in the boil
2.9 HBU @5 min = 2.5 IBU in the boil
so then the 3 gal boil almost doubled (* 1.8 actual for 5.5 gallons)
32.67 IBUs in the fermenter, Tinseth method, should match pretty good on bitter-flavor - aroma. Gonna try it.
EDIT: 11-18-07 I bottled the first batch with 11.8 HBUs of cascades. It is good beer, I don't expect to pour it down the sink. In fact, I really like it, just not the hops I expect in an APA. Not an expert, this is hoppier than say Newcastle brown, but less hoppy than beer in a box English Pale Ale from Muntons. For now my second batch with the 19.1HBUs was still at 1.018 this AM, so maybe next weekend.
EDIT: 11-25-07 I got the 11.8HBU Cascades version bottled about a week ago. The 19.1 HBU Sterling version was bottled on 11.21-07 and the 21 HBU Saaz bitter / Chinnook aroma, flavor is still in secondary.
EDIT III: 11-29-07. I got into the first 5.9% Cascades batch tonight. Not fully carbonated yet, but :rockin:
EDIT IV: 12-08-07: I kegged my third batch about thirty minutes ago. I was shooting for F-W Pale hop clone, I used (60) 4.25HBU Saaz and 3.0HBU Hallertau. (30) was 6.4HBU Hallertau, (15) 3.78 HBU Chinook, (5) was 3.25 HBU Chinook. flat, about to force carb, it is close enough to start fooling with the grains and use all the same noble bittering hop next time.
EDITV: 02-02-08: The 21HBU version described in editIV is the best beer recipe I have ever tweaked. Once it was carbed this stuff kicked absolute butt. I started out trying to clone Firestone-Walker Pale. I think I surpassed them on hops balance. If I had the space to go all grain I would be going after their grain bill, but only because I like that beer so much.
EDIT VI: 02-09-08: I now agree with HB_99 from experience and I now add my *ME at flameout. All of the hop U calcs in this post on page 12 are for *ME addition with 15 minutes left in the boil. If you want to see some hop U for *ME at flameout, jump forward to post 272 on page 28 this thread:
https://www.homebrewtalk.com/showpost.php?p=550033&postcount=272