Carver AV 64 Cathedral Amp- how to bridge

Hey Folks,

Just picked up my 3rd Carver; a Carver AV 64 Cathedral amp

Im been searching for information for a while with this one and cant seem to find a manual anywhere.

I bought the unit as hit has the ability to bridge channels 1 and 2 to output 180watts to one speaker (center channel)

It has a Derived Center channel, that works when i have one rca in either channel 3 or 4. if i put and into both channels the sound coming from the channel gets muffled.

The details below say that channel 1/2 have to be bridge to get 180watts.

The issue is that unlike my other two (TFM 55x and TFM 15cb) this one doesnt have the "guide for bridging" printed on the back

Snapshot of Spec page:


Heres an image of the rear


Any help will be great

I can't read the back, but is there a slider switch that says "mono"?

I can't read the back, but is there a slider switch that says "mono"?

Yup, it has a push button, next to that is a biamp button

Well, if seems to me that a little experimentation with a volt meter should be able to determine this empirically.

Bill, you are the only one around here who determines anything EMPIRICALLY~

Well, if seems to me that a little experimentation with a volt meter should be able to determine this empirically.

Yeah... not to handy with the volt meter. - I guess il learn that first them figure this out.

Id basically play a dvd, turn on my receiver so i can send it sound to the amp, the rca into the channel A or B input, then touch the speaker terminals to see what combination outputs the most volts

That will be my bridged channel??

What would the volt meter be set to?

Well, a test tone would probably be best (say 1000Hz from the Carver test CD). Anyway, with no speakers attached put the output from the CD player directly into the amp. Then you play around for maximum voltage at the speaker terminals. How much voltage. Well, the most you should run into is 180 Watts. It doesn't say whether that's into 8 or 4 Ohms, but we should assume 8, because that will be the largest voltage. Consider that W=V²/R, with 180 for W and 8 for R, we get the square root of 1440 for V, or about 38 Volts. Depending on how much your CD player puts out, it will certainly be around there or less. So if your meter is autoranging, you really don't need to worry. Otherwise, a 50V scale would be fine.

Well, a test tone would probably be best (say 1000Hz from the Carver test CD). Anyway, with no speakers attached put the output from the CD player directly into the amp. Then you play around for maximum voltage at the speaker terminals. How much voltage. Well, the most you should run into is 180 Watts. It doesn't say whether that's into 8 or 4 Ohms, but we should assume 8, because that will be the largest voltage. Consider that W=V²/R, with 180 for W and 8 for R, we get the square root of 1440 for V, or about 38 Volts. Depending on how much your CD player puts out, it will certainly be around there or less. So if your meter is autoranging, you really don't need to worry. Otherwise, a 50V scale would be fine.

Ill give it a try - any warnings that i need to know about so i dont fry anything.

Just to be straight, plug a cd/dvd player directly into one of the channels (even though i dont have any gain control on the amp)

Take the two prongs from the meter and touch the red and black, then the red and red of speaker A+B, until i get the highest reading.

Does that sound right? sorry about all the questions.

Damn it i wish i could find the manual. is there not a place i could call??

Don't short between the output terminals of the amplifier. Yes, red to red, black to black.

But some amp require you to connect the black speakers cable to the red terminal of channel A and the red speaker cable to the red terminal of channel B

Some amps like my TFM 15cb bridges in with this method:
RCA into Channel 1 or Left
RED(speaker wire) TO RED(speaker terminal A )
BLACK(Speaker wire) to RED(speaker terminal B)

If the amp is not meant to do this would i blow it doing the meter testing??

Others do it like this:
RCA into Channel 1 or Left
RED(speaker wire) TO RED(speaker terminal A )
BLACK(Speaker wire) to BLACK(speaker terminal B)

You are measuring AC, so it won't matter. We are looking for voltage, not phase. I'm guessing that this is a common ground amp (because it has a switch). What you are measuring is the potential difference between two points. If they both have the same voltage, you will get zero. I'd be guessing the left input is where you want to put the input (because it seems that Carver always did it that way). My guess is the two hot (red) leads will be the output.

SO, yes, you will need to measure between REDs too.

Well here are my findings - hang on
Below i have also added volt readings on my meter which was set to 200v (lowest i could go) acv
(mind you that this is the first time using a volt meter)

So heres whats on the back of this unit
total of 4 rcas in labeled 1-4 (there are also other outputs for biamping)
5 speaker terminals
1-4 channels and a derived center channel

tests:
With MONO pressed in
RCA IN Channel 1(then same series of tests with channel 2 rca input)
Speaker terminal combos
CH 1(red) + CH 2 (red) =very low vol/10 volt
CH 1 Red + Black = loud/10 volts
CH 2 Red and + Black = Loud/10 volts
CH 1 Red + CH 2 Black = Loud/10 (tried other way around as well)
Derived Center channel = nothing/0 volts

With MONO not Pressed
RCA IN Channel 1, then same series of tests with channel 2 rca input
Speaker terminal combos
CH 1(red) + CH 2 (red) = loud/14 volts
CH 1 Red + Black =loud/12 volts
CH 2 Red and + Black= nothing/0 volts
Derived Center channel = nothing/0 volts

So with mono selected - channel 1 and channel 2 terminals are outputing sound regardless of channel input
Red and Red with mono are very low

Heres the kicker
Channels 3 and 4 testing are as follows
no difference Mono pressed or depressed

When using rca 3, the derived center channel works and is louder/20 volts than any CH1 or CH 2 combo
the channel 3 out put is just as loud/20 volts as the Derived center
When using rca 4, the derived center channel works and is louder//20 volts than any CH1 or CH 2 combo
the channel 3 out put is just as loud//20 volts as the Derived center.

Channel 3 and 4 both have there own gain controls aswell
if i put rcas left and right from the dvd player into channel 3 and 4- the sound is all muffled from the derived center, but the channel 3 and 4 outputs are Crystal clear

Im am very confused, why or why bob did you close shop.
can i call sunfire??? is there anyone that i can call?

Try calling Rita, I think this is the correct #? 425-530-9557
Or check out their site > http://www.ritasvintageaudio.net/

I agree there has to be an easier way, I'm also confused! Let us know what you find out. Thanks

P.S. I think BillD got us all confused He needs to stop taking those blue pills!

Yeah, those readings are very confusing. I'll take the red pill tomorrow.

Just email ritas, hopefully i get some answers - im itching to use this with my center channel