(Older) Trace Elliot tuning ports?

The plugs/caps change the cab from ported to sealed.

In ported mode it is louder but does not extend so low.
Adding one plug cuts the output slightly but lowers the lower frequency resonse.
Adding both reduces output further and lowers the lower frequency response further.

I have the 1 X 15 combo with the same amp and graphic preamp but double the output power so you can run an extension cab. When I first got it I tried messing about with the tuning plugs and ended up leaving them out (and loosing them). If I can dig out the manual I will post the specs on them.

As a side note. There is an inherent design fault in the amplifier section. There is a missing star washer where the power amp earth is connected to the chassis. Without this there is a distinct possibility that it will self destruct or self combust as mine did. As far as I recall the chassis connection is at the front left corner of the power amp. Remove the screw and check that a star washer is fitted. If not fit one. Most old ones have self destructed and been replaced with the more modern mosfet replacement.

I have a pdf of the complete service manual if you want to PM me.

 

Wonders will never cease. I have found my original user manual and receipt, not bad considering that I bought it in 1997.

Both ports plugged = Infinite baffle
One port plugged = Reflex enclosure tuned to 35Hz
Both ports open = Reflex enclosure tuned to 45Hz

 

That is where the star washer should be, between the tag on the end of the wire and the chassis. It can be fine for years but get a little bit of corrosion in there and the whole thing goes unstable, starts making random frying bacon sort of sounds and eventually takes the power amp out. Mine then took the speaker as well.

TE recognise this and it an official mod to add a star washer.

Mine is a 7215SM, 7 for 7 band graphic, no idea what the 2 means but probably for it's 2 preset bass shapes , and 15 for 15" speaker, SM is for Sound Mangement. I bought it new in 1997 and apart from the little episode with the star washer has been a superb amp (combo). I fitted the later mosfet power stage and an Eminence Delta speaker, plus a couple of piezo horns because the Delta's top end range was a fair bit down on the original Celestion.

The first thing I did with mine was fit a set of wheels on it and get a cover. It looks almost new and has done hundreds of gigs. If you are keeping it then it is not a bad idea to blow the dust out of the heatsink and fan every few months.

 

The star washer digs into the metal on the chassis and tag resulting in a lot higher pressure over a smaller area. This higher pressure means any moisture is less likely to get in and cause corrosion.

Maybe where you are there is not that much condensation, but if I take my amp out of a cold car or van into a hot humid club and set the fan going it gets condensation inside it in seconds.

Not only did my combo look very much like that but it still does, I gig with it regularly. Mine is 280W RMS total. I never use peak as the only real measure of power is RMS.

Nowhere on the combo does it give the model number but the receipt and the registration details list it as 7215SM. It is slightly different to yours, I suspect yours is a newer model with slightly different graphics. Also mine is 280W as opposed to your 130W. Maybe the 2 means it will run an extension cab as well. Only once have I done this as it is usually quite loud enough. I ran an 8 ohm Peavey 4 X 10 and it sounded really good.

I am still looking on old disks for the manual, will send when I find it.

It is very clean for it's age, mine is fairly clean but it has seen a lot of action so is bound to have deteriorated after 13 years of regular gigging. I do periodically blow it out with an airline and give the rat fur a good clean with a Hoover. What looks the worst is when dust settles in the ports.

 

doohh, never thought of that.

Manuals are on their way, user and service.

I am interested in what you think of it.

 

I'm sure if you do get to use it on Wednesday that you won't be disappointed.

 

I don't think you, or the new owner, are ever going to have a problem with a bad earth connection now but you may have to update the spec weight to include all these star washers.

 

Phat and delta7,
Think I could get a copy of those manuals since I am the proud new owner of Phat's trace combo

thanks,
Brian

 

Cool, found one on the British Audio Repair website

 

Brian

Sorry for the delay, I have been away for a week.

Is it the full service manual, or just the user manual?

If you want the full service manual PM me and I will send it. or if you are a member of freestompboxes.org then it is here

http://www.freestompboxes.org/download/file.php?id=7186

fred