Are all Hiwatt cabs ported?

[shakti]

Subject says it all. Were all the old Hiwatt cabs ported, including the late 60s ones? Or only certain models/vintages?

[OldSchoolDave]

Yes.

Unless there were some very early prototype exceptions, Hylight Hiwatt cabs were either rear ported via a slot in the back panel or front ported via 4 round holes in the baffle.

Dave

[shakti]

Thanks! I just wanted to know how different my soon-to-arrive late 60s Sound City cab might be. Not sure yet if it's ported or not.

[Dr.HI-TONE]

Post pics when you get it. I have been dying to see it and get a tone report!

[shakti]

Will do! It won't sound quite right until I have that CP103 assembled for it though...

[Dr.HI-TONE]

I'm working on it.

[OldSchoolDave]

How big? How Many? And where?

(port holes)

Just took a bunch of cabs to storage, so I can't give you exact dimensions. The slot on the rear loaded cabs isn't all that big. Here's a pic of my front loaded cab, where you can see the 4 round ports:

Grille_off_1.jpg (98.95 KiB) Viewed 4724 times

One of the later users of the Hiwatt name made a diagonal 2x12 cab that sounded pretty good. Hiwatt Bob's got one. Not sure if any other members do or not.

Dave

[shakti]

Update: I've been using my 69ish Sound City 4x12 with 50w Fanes with a new CP103 build. While the amp needs much more burn-in and a little tweaking, it's sounding a little harsh and fizzy with this cab, particularly at high volumes. The clean sound of this cab is really rich and vibrant, but it gets quite nasty sounding when the volume is loud and there's distortion from the amp. It sounds like the treble crackles and the bass becomes congested and farty sounding.

I'm speculating that it's due to the lack of porting on the cab, and the fact that the Fanes are very hi-fi, full-range sounding (compared to Celestions), and the CP103 has rather little compression, but at a certain point of breakup/distortion and volume, the speakers are not working to their full potential in a closed back cab. That effect does sound very pleasant with a Marshall amp and cab setup, being rounder and more compressed sounding from the start, it all adds up to a very smooth legato sound, but with this setup there's just too much extended high end and low end, and it ends up sounding cluttered and harsh.

I want to try my cab with a ported back panel. Can anyone show me the construction of a late 60s or early 70s Hiwatt cab? I can't find any good photos on the web. In particular, I'm wondering if my particular cab has the same construction as a same-era Hiwatt cab. I think I read somewhere that at the time (68-69) both Sound City and Hiwatt cabs were made by the same manufacturer, and were almost identical except for the rear port on the Hiwatt cabs. Is this true?

[OldSchoolDave]

I think I read somewhere that at the time (68-69) both Sound City and Hiwatt cabs were made by the same manufacturer, and were almost identical except for the rear port on the Hiwatt cabs. Is this true?

Many of the British cabs were made by the same manufacturer. There are similarities between SC and Hiwatt cabs but, I believe, materials may have differed (by customer spec).

I suggest you cut a new back out of good 3/4" ply and add a rear slot to test your theory. As your SC cab will have a batten all the way across the bottom, you'll have to cut the test port taller (assuming you don't want to modify your vintage cab).

Dave

[shakti]

Thanks! I did find an older post here which said the rear port was 17" x 1/2", is that correct? And I take it that it was placed all the way down along the lower bottom edge?

I'll try it with the back taken off completely first (but will add a little attenuation, as I'm afraid the lack of compression might cause the drivers to move a little *too* freely...).

[shakti]

BTW, my SC cab does appear to be made out of 3/4" birch ply, both the shell and back panel. Baffle is also birch(?) ply, not sure about thickness, front loaded and secured to the interior bracing with fastening nuts from the inside. It appears to be very similar to Hiwatt cabs, except it has metal handles bolted into place ather than wooden handle blocks, and the lack of rear porting.

[OldSchoolDave]

Thanks! I did find an older post here which said the rear port was 17" x 1/2", is that correct? And I take it that it was placed all the way down along the lower bottom edge?

Yes, that's correct. Here's a bad pic of a much worn cab, but it should tell the story.

SE412_port.jpg (115.44 KiB) Viewed 4595 times

Dave

[shakti]

Thanks! I tried the cab without a back panel last night, it did seem to ring a little more openly this way and not get as congested sounding. I'll make up a new, ported back panel for it.

[shakti]

I just found a photo in a Who - Maximum R&B book by Richard Barnes from the Rock 'n' Roll Circus. It's a photo of The Who clowning around in the crowd during a break, but in the background you can see the rear of what appears to be their stacks. The cabs do appear to be Hiwatts, with recessed handles and the back panel screws mounted in the exact same pattern as my Sound City cab, i.e. no screw directly in the corner, but offset slightly to each side. Everything points to them being the Hiwatt cabs with herringbone grille cloth used during their performance. In this photo, you can see quite clearly that there's no port, neither on bottom nor the top.

AFAIK, these cabs, or at least ones similar to these, with Hiwatt badges and herringbone grillecloth, were used occasionally as late as 1971, or at least 1970.

[Dr.HI-TONE]

AFAIK the Rock and Roll Circus cabs were rebadged Sound City cabs.

They sounded good to me!