Bobby's Dad's thread....

[laatsch55]

Will have to take a careful look. I think this amp was set up in a bridged mode so we have to be careful to see if it is properly ground referenced for separate stereo operation.

Meaning the ground is floated during bridged mode and tied back in during two channel operation??

 

[Gepetto]

Meaning the ground is floated during bridged mode and tied back in during two channel operation??

Yes, that is correct Lee. What normally is a signal ground return becomes an anti-phase output of a second amp channel to achieve higher power output with the same supply voltage.

 

[laatsch55]

Yres I understand the bridging concept that say the left channel handles the upper part of the waveform and the right chann el the lower. So, how do the speaker grounds become become a positive return. Gotta be some switches involved/.....

 

[Gepetto]

Take your time Joe.
I won't have a s/d transformer (240v - 110v) 'till the end of next week, so there's definitely NO urgency for this.
I so appreciate your help tho'

George

Hi George
Some serious chassis rewiring to get this to be 2 independent channels. Are you sure you are up to this and are you sure you want to do this to this amp?

Let me know before I spend any time marking up this schematic.

You will have to carve up the chassis to add another set of input jacks and output posts.

Joe

 

[pennysdad]

Hi George
Some serious chassis rewiring to get this to be 2 independent channels. Are you sure you are up to this and are you sure you want to do this to this amp?

Let me know before I spend any time marking up this schematic.

You will have to carve up the chassis to add another set of input jacks and output posts.

Joe

No Joe, I don't. (but really I do.)
For the sake of maintaining this amps integrity, I'm prepared to leave it alone as is.

In regards to adding any new speaker posts tho', I should add that this amp does still have the binding posts for two channel operation, and they are wired separate all the way to their respective channels.
There are no switches of any kind anywhere.
Any bridging is done at the power amplifier modules' inputs.
... but let's throw this one into the 'too hard' basket.
It's better to be safe than sorry.
Thanx heaps n' heaps for your time Joe. Very much appreciated.

Most sincerely,
George.

 

[NavLinear]

So - will the step down transformers be a problem? I'll ass-u-me that the cost is part of the issue and it's just nice not to have to use something like that. I used them in Europe years ago although all of my stereo equipment had either a switch for 220 or 110 except my PL 400 amp and Soundcraftsmen pre - both had to be rewired for 110 when I returned to the US. Both were simple wire mods - but they were designed that way.

Anyways I hope it all works out and good luck dude - aka mate.

 

[pennysdad]

So - will the step down transformers be a problem? I'll ass-u-me that the cost is part of the issue and it's just nice not to have to use something like that. I used them in Europe years ago although all of my stereo equipment had either a switch for 220 or 110 except my PL 400 amp and Soundcraftsmen pre - both had to be rewired for 110 when I returned to the US. Both were simple wire mods - but they were designed that way.

Anyways I hope it all works out and good luck dude - aka mate.

Dennis,

.... no, the SDT won't be a problem, but finding one (or two) that can do the job and cleanly, that's the 'iffy' bit.
I'm looking at one in particular on the 'Bay, which seems to be capable of doing the job, but I just don't know about any noise or whatever other problems I might encounter.
They're eighty bucks a pop, and I'd need two as they're rated a 2KW, and the 7B's are 1.5KW, so it's worth a try. If I get one and see how it goes, and if all's good, I'll buy another one.
Keeping in mind, that one 'might' do the job if I don't try to set any new SPL records for this Apartment Block and not try to turn on both amps at once. If THAT works without overheating the SDT and nuking it, then I can take my time to get the other one when I can afford it, (AFTER paying off all this sh*t.)
Remember, I am but a bottom dwelling pensioned off poor person, but a bargain is a bargain and these were just a 'must have' for the price. Me and the kids can go hungry for a while...... Heh heh heh...

 

[NavLinear]

That was a good score George and with all said and done it should kick ass. I'm looking forward to "hearing" the results. Go catch a mouse or two - that'll keep the kitties happy.

 

[laatsch55]

Kitties can catch they're own mice and bring one home to poppa once in awhile.

 

[NavLinear]

Kitties can catch they're own mice and bring one home to poppa once in awhile.

Yes they can - just not sure what an Aussie cat can do though! Just might be one of them thar' marsupial kitties.

 

[pennysdad]

Kitties can catch they're own mice and bring one home to poppa once in awhile.

the only time they hunt for food is when they're getting served their breakfast/lunch/dinner, in bed and it's right under their nose!
and then, it's "nah, I don't feel like that today, make me somethin' else....."
of course, I do.

 

[pennysdad]

My dream amp is finishing soon....

http://www.ebay.com/itm/Radford-STA...dioHiFi_Amplifiers&hash=item460f75cb62&_uhb=1

So sad....

 

[laatsch55]

Your dreams are expensive....

 

[pennysdad]

Your dreams are expensive....

it will double that by the time it finishes....

 

[NavLinear]

it will double that by the time it finishes....

If it doubles just fold it in half.

 

[pennysdad]

If it doubles just fold it in half.

 

[NavLinear]

Sorry - I just crack myself up. It doesn't take much.

 

[pennysdad]

Sorry - I just crack myself up. It doesn't take much.

you can get a special cream for that...

 

[NavLinear]

you can get a special cream for that...

Too funny!!!!

That does remind me of a story though. I've worked for our government for several decades and one of my orders was questioned by our supply system.

My request was for anti-bacterial soap.

I was asked why I needed anti-bacterial soap.

I replyed that I searched and searched for bacterial soap but couldn't find any so I ordered the anti kind.

 

[laatsch55]

That's hilarious, especially when ya see anti-seize being ordered as Sieze, anti. LMOAO!!!