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BGW amplifier - Replacing 1/4" inputs with RCA

RemoWilliams

RemoWilliams

Addicted Member
Looking inside it appears that BGW mounted the 1/4" inputs on a board, along with the balanced input / outputs and the stereo / mono switches. Model is the GTB.


Apparently schematics are difficult if not impossible to find though I wonder if one could at least simply desolder the balanced and unbalanced from the board and hopefully trace the wires on the multi pin connectors, finding the unbalanced + and - and then soldering them to some replacement RCA inputs.


Of course, I could simply continue to use the 1/4" to RCA adapters that I have, there are some decently made ones available but simplifying the signal path is tempting. Not well versed in electronics unfortunately but can do the basics.

I can't say the system sounds off or un engaging - using KEF 105.1 and the two BGW power amplifiers certainly do a good job ( the GTB is for the 12" driver and another BGW for the mid / tweeter ).


Unfortunate that it was not an easier modification. Looking at the speaker binding posts not sure if I should bother replacing them, was going to solder the wires directly but a bit too hefty plus I see they used a common grounding point as well. Maybe some copper ring connectors instead of the aluminum ones?





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Honestly, I'd keep the 1/4" jacks. That's what I do on my amps that have them. One of my old QSC's has only a terminal block for inputs, which is pretty inconvenient. I installed 1/4" jacks on it and use adapters when I need an RCA. To clean things up, you could just use RCA cables with 1/4" jacks on one end; that'd eliminate one set of connections. Another option, if I still felt the need to have RCA's, I'd just add them to the back panel. I've seen some like this that have a toggle to select balanced or unbalanced, but that'd add another set of connections.
The binding posts should use standard 3/4" spacing, so any standard double banana jacks will fit. I'd keep the screw terminals, though. That's a lot of wires to have to solder to what's a fairly small post.
 
I have a bunch of pro amps, and also hate 1/4” jacks. Especially when they get old and loose. I just got an amp yesterday that only has 1/4” input and outputs. I’m most likely going to switch them to RCA and binding posts.

I love the amps that have options. A lot of my Ashly amps have 1/4”, terminal strip, and XLR inputs.

So OP, if you think you can remove the 1/4” jacks and replace them with RCA, I would do it. I would do that before cutting/drilling the case to add the RCAs.
 
1/4 to RCA cables in decent quality can also be had for not-dumb money. Had to buy some to get signal in and out of my old reel to reel.
 
For all the people that say to just use adaptors, what would you tell the OP if he said the original 1/4” plugs were worn, corroded, or otherwise not serviceable? Replace with more 1/4” jacks?

I think this is a pretty common upgrade for people who are using older pro amps for HiFi. It’s probably easier to do on some amps than others.

The OP says he already has/uses the 1/4” to RCA adapters.

@ivandezande
What is it that BGW amps do so poorly that we shouldn’t be concerned about the signal path? Or is this a “pro amp in general” comment?
 
elitopus said:
For all the people that say to just use adaptors, what would you tell the OP if he said the original 1/4” plugs were worn, corroded, or otherwise not serviceable? Replace with more 1/4” jacks?

I think this is a pretty common upgrade for people who are using older pro amps for HiFi. It’s probably easier to do on some amps than others.

The OP says he already has/uses the 1/4” to RCA adapters.

@ivandezande
What is it that BGW amps do so poorly that we shouldn’t be concerned about the signal path? Or is this a “pro amp in general” comment?
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Pro amp in general. The signal path through an adaptor is the least of the worries.
 
elitopus said:
For all the people that say to just use adaptors, what would you tell the OP if he said the original 1/4” plugs were worn, corroded, or otherwise not serviceable?
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But he didn't.

As suggested already, a 1/4" to rca cable is a simple, inexpensive and elegant solution, if he's concerned about limiting the number of connections in the signal path.

As for the ring terminals, OP, it's quite likely that the ones already installed are tinned copper, not aluminum. If so, there's no reason to replace them if they're not damaged.
 
I did clean the inside of the 1/4" inputs, there was a good amount of general grunge so at least they are good as new, the jacks also are quite secure and engage with a solid click.If anything the RCA end on the adapters are alright but nothing special. For now I will purchase another pair of good quality , the one amplifier for the mids / tweeters has rather cheap ones made of steel, I found a set that at least use copper with gold plating so better than nothing while I give the modification some thought.


One part I definitely had to replace was the original A.C. fan on the GTB, talk about loud. In its place is a 1,000 rpm 12 V D.C. computer fan operating at 9 volts which reduced the rpm further, very quiet and still moves more than enough air. The other amp is a 7500 Pro Line II that does not use a fan although runs quite warm. As it has only 1/4" jack inputs I will probably take a peak inside , it might be a bit more straight forward.
 
elitopus said:
I have a bunch of pro amps, and also hate 1/4” jacks. Especially when they get old and loose.
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Having been a pro sound guy, I find 1/4” to be pretty robust and easy to repair, especially when compared to an RCA. If size and bend radius were not an issue, I’d take 1/4” over RCA any day. Use an adapter cord..
 
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BTW, congratulations on the BGW amp. I think those pro amps can be a bargain. However, they were usually put into installations where they were run hard, bounced around, or exposed to awful crap. I hope it works out for you.
 
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I have run Crown amps in my home systems for over 50-years and never encountered a problem that wasn't the fault of poorly made (cheap) 1/4-inch plugs. Using good quality name-brands either adapters or 1/4-to-RCA cables has never caused a problem.

Don't mess up a good thing! :thumbsup:
 
RemoWilliams said:
Apparently schematics are difficult if not impossible to find though I wonder if one could at least simply desolder the balanced and unbalanced from the board and hopefully trace the wires on the multi pin connectors, finding the unbalanced + and - and then soldering them to some replacement RCA inputs.
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You might want to note polarity as these earlier BGW's do not observe standard XLR pinout.
 
Man I wish someone told me sooner that pro amps suck. Now I’m stuck with a bunch of paperweights :D

Btw, the GTB looks like a pretty nice amp. I have a BGW 250, 600, and 750.

And I still hate 1/4” jacks
 
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