GPA 604 adventures

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Yeah, I've been hoping one of the locals with a duplex would be a 'guinea pig', but no luck. I figure if anything will sound good in a K15 that would be it, because for sure the big whizzer cone EV was unlistenable 'fullrange'.

Made a great corner 'sub' with the EV on a small OB though. The XO was something Jack built from Popular Electronics and the rest of the electronics was gutted from a '30s era Sears Silvertone console made by RCA.

GM
 
Jean Hiraga's personal explanation of his Altec 604-alnico cabinet construction draws-out like putting large Onken style ports on the bottom of the cabinet.

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Great info here, I'll treasure them!

About Karlsons, I've never had the chance to hear one.
What about imaging? With the speaker so low, I'm expecting dwarfish singers and players, as for my current OB panel.
 
604 MLTL cabinet discussed
 

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One of my speaker is UREI 813C, a 604 variant, made by JBL for pro market, and I guess it is one of the closest cousin of the GPA 604 8H. It has an additional 15" woofer for the bass in a huge enclosure. I tried many different configuration with this unit, including OB, active crossover / multi amps, but I currently use original JBL / UREI configuration with some digital EQ added.

It is not as accurate nor extended as today's good speakers whatever I tired (and you may have already noticed), but it has own charms. I love them. The midrange can be really good, but if one tries to extend the bass and treble for flatter response from 30-20K, the midrange magic should be gone, IMO. I prefer to hear it with less extended FR, respecting intrinsic nature of the vintage Altec design, even they are one of the largest speakers in my house.
 
What about imaging? With the speaker so low, I'm expecting dwarfish singers and players, as for my current OB panel.

It has a very wide horizontal power response, so lots of overlap in a typical size room to the point where they ideally need to be on the long wall. Anyway, IIRC Freddy has done some polars.

Not quite as bad as you might think due to floor loading, no floor 'bounce', but notice in a recording studio: https://images-na.ssl-images-amazon.com/images/I/513R85Qg2LL._SY445_.jpg

GM
 
Hmm, to me, this means low friction, which in speaker vent design 'speak' is either a very low vent mach [large] at one extreme or 'aperiodic' [resistive] vent at the other extreme or a combination of the two, so my SWAG is he's done both, which may include some fine tuning with one or more types of damping materials to both act as a protective grill and 'critically damp' it same as the pioneers did.

In short, in its simplest form and as previously noted by 'Linesource' earlier, an 'Onken' concept, floor loaded vented base with maybe a [protective] grill somewhere along its length: GPA 604 adventures

GM
 
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