Far too lean 604-8Gs in 620 kabs

**KBergsson** · September 21st, 2011, 02:39 AM

Originally Posted by cradeldorf

Yaayyy!!!!!!!!!!!!!!!!!

GM · September 21st, 2011, 03:40 AM

Originally Posted by KBergsson

Then I tried bypassing the eq altogether, wow!! Top a little hot but there wa a lot better overall balance.

Greets!

Interesting, sounds like your amp is the real problem, i.e. can't handle the load of all the extra series resistance, causing it to 'lay down' on high current demands. If true, then using a tapped auto-former to adjust the HF's level like was used back when high output impedance was the norm seems the way to go. Regardless, glad you found at least a temporary workaround.

GM

**bowtie427ss** · September 21st, 2011, 08:16 AM

If the OP's amplifiers have multiple taps, i wonder what effect using the 4 ohm taps might have had in coping with the additional series resistance of the JM network.

FWIW, i've kept all my 8 ohm Altecs and they're fed only clean quality(not heavily damped) solid state watts these days. The result for me has been a lot more listening time, and a lot less chasing my tail after "sonic anomalies". My next amplifier project will most likely be a Nelson Pass/Firstwatt F5, that's if i don't get too anxious and get a built model.

Just my .02................. YMMV.

**KBergsson** · September 21st, 2011, 09:37 AM

Thanks GM and Bowtie, I'm going to play for a while with the crossover as is (ie bypassing the mid eq) and see if I miss the eq at all.
Using autoformers could be interesting, are there standard (vintage) ones available or do they need to be tailored to the actual speakers?
I will on all account try the 4 ohm taps and see what that does.
Regards
Kjartan

**omodo** · September 21st, 2011, 06:42 PM

There's a guy from Germany who produces some nice c-core autoformers designed for use with Altecs, you can find him and the autoformers on eBay under the username mast_mutter. You can either buy a complete crossover network or order the autoformers and/or c-core inductors separately, his 604 network is very simple but works very well. PM if you would like his email address, otherwise you can contact him via eBay.

**speakerdave** · September 22nd, 2011, 12:38 AM

Originally Posted by KBergsson

Just removed the Altecs 604s and removed som fiberglass from 2 sides in each speaker. Initial impression: more open/transparent or lively sound. The bass membranes are stamped 1803035662 and 1803035(5or6) cannot se last two figures.
Does this indicate original membranes or later recones?
Regards
Kjartan

If anyone responded to this I missed it. Those are not Altec cone numbers for the 515b/604G, so they are apparently recones. I don't recognize the numbers, so i cannot place the source.

**KBergsson** · September 22nd, 2011, 03:43 AM

Originally Posted by omodo

There's a guy from Germany who produces some nice c-core autoformers designed for use with Altecs, you can find him and the autoformers on eBay under the username mast_mutter. You can either buy a complete crossover network or order the autoformers and/or c-core inductors separately, his 604 network is very simple but works very well. PM if you would like his email address, otherwise you can contact him via eBay.

Thanks Omdodo I will check out mast_mutter.
Just got a homemade headamp yesterday ( j.j. Curcio mc stepup with E88CC / 6922) , so now I got valves all the way - life is good

Regards
Kjartan

**KBergsson** · September 22nd, 2011, 03:45 AM

Originally Posted by speakerdave

If anyone responded to this I missed it. Those are not Altec cone numbers for the 515b/604G, so they are apparently recones. I don't recognize the numbers, so i cannot place the source.

Thanks speakerdave, that explaines why they look "new".
Regards
Kjartan

**KBergsson** · October 2nd, 2011, 03:41 PM

Originally Posted by omodo

There's a guy from Germany who produces some nice c-core autoformers designed for use with Altecs, you can find him and the autoformers on eBay under the username mast_mutter. You can either buy a complete crossover network or order the autoformers and/or c-core inductors separately, his 604 network is very simple but works very well. PM if you would like his email address, otherwise you can contact him via eBay.

Hi omodo, I have ordered the autoformer crossovers for altec 604 from mast_mutter. Look forward to try them

Regards
Kjartan

**KBergsson** · October 23rd, 2011, 11:36 AM

Originally Posted by KBergsson

Hi omodo, I have ordered the autoformer crossovers for altec 604

I have now connected the autoformer crossovers from Werner Jagusch. They are an incredible improvement compared to the original crossovers and my implementation of the Markwart crossovers. These big speakers disappear and the sound is smooth, effortless and with astonishing realism (Im now using a Shure V15VxMR on my VPI Classic).
Im attenuating the horns approx 4.5db compared to the woofers (if my assumption of 1.5db per step is correct). Gives me a lot better balance than before.
Kjartan