# modify AMI/Rowe 50w hybrid power amp to use 4 or 8 ohm speakers

USSEnterprise

04.04.2011 - 04:44

04.04.2011 - 04:44

I have an AMI/Rowe TI-1 with a 50 watt hybrid power amp. Is it

possible to modify the amplifier to use either 4 or 8 ohm speakers,

instead of 10 and 15 ohm ones?

Thanks

Joe

Rob in NYC

04.04.2011 - 06:45

04.04.2011 - 06:45

transformer taps of E1- and E4 produce rated output (25W/ch) into 8

ohms. Years ago I made a wattage chart based on voltage readings for

these Rowe amps, I'll look for it. BTW: That combination should also

work for the transistor amps.

Rob

On Apr 3, 9:440pm, USSEnterprise <starbas...@gmail.com> wrote:

Hello.

I have an AMI/Rowe TI-1 with a 50 watt hybrid power amp. Is it

possible to modify the amplifier to use either 4 or 8 ohm speakers,

instead of 10 and 15 ohm ones?

Thanks

Joe

USSEnterprise

04.04.2011 - 07:24

04.04.2011 - 07:24

has 2 12AX7's and 4 7868's. According to a manual I found online for a

similar juke that uses the same amp, the woofers were 15 ohms, and the

mids and tweets were 10.

On Apr 4, 12:450am, Rob in NYC <lino20...@yahoo.com> wrote:

Joe, by "hybrid"-do you mean tube power amp? Is so, I found that the

transformer taps of E1- and E4 produce rated output (25W/ch) into 8

ohms. Years ago I made a wattage chart based on voltage readings for

these Rowe amps, I'll look for it. 0BTW: That combination should also

work for the transistor amps.

Rob in NYC

04.04.2011 - 08:20

04.04.2011 - 08:20

OK, I have not found my chart yet, but here is a scan of am AMI/Rowe

amp's power distribution and wattage chart:

http://s1192.photobucket.com/albums/aa337/Rob-NYC/

this is essentially the same tube amp as your, the only thing is that

they didn't calculate for full power to an 8 ohm load, probably

because they expect machine speakers to be part of the load.

At any rate, E1-E4 will deliver full power to an 8 ohm load. If you

have a 4 ohm load, use the E2-E4 points.

Rob

On Apr 4, 12:240am, USSEnterprise <starbas...@gmail.com> wrote:

Its called a hybrid amp in the schematics, but yes, it is tubes. It

has 2 12AX7's and 4 7868's. According to a manual I found online for a

similar juke that uses the same amp, the woofers were 15 ohms, and the

mids and tweets were 10.

On Apr 4, 12:450am, Rob in NYC <lino20...@yahoo.com> wrote:

> Joe, by "hybrid"-do you mean tube power amp? Is so, I found that the

> transformer taps of E1- and E4 produce rated output (25W/ch) into 8

> ohms. Years ago I made a wattage chart based on voltage readings for

> these Rowe amps, I'll look for it. 0BTW: That combination should also

> work for the transistor amps.

amp's power distribution and wattage chart:

http://s1192.photobucket.com/albums/aa337/Rob-NYC/

this is essentially the same tube amp as your, the only thing is that

they didn't calculate for full power to an 8 ohm load, probably

because they expect machine speakers to be part of the load.

At any rate, E1-E4 will deliver full power to an 8 ohm load. If you

have a 4 ohm load, use the E2-E4 points.

Rob

On Apr 4, 12:240am, USSEnterprise <starbas...@gmail.com> wrote:

Its called a hybrid amp in the schematics, but yes, it is tubes. It

has 2 12AX7's and 4 7868's. According to a manual I found online for a

similar juke that uses the same amp, the woofers were 15 ohms, and the

mids and tweets were 10.

On Apr 4, 12:450am, Rob in NYC <lino20...@yahoo.com> wrote:

> Joe, by "hybrid"-do you mean tube power amp? Is so, I found that the

> transformer taps of E1- and E4 produce rated output (25W/ch) into 8

> ohms. Years ago I made a wattage chart based on voltage readings for

> these Rowe amps, I'll look for it. 0BTW: That combination should also

> work for the transistor amps.

kreed

04.04.2011 - 12:48

04.04.2011 - 12:48

On Apr 4, 12:440pm, USSEnterprise <starbas...@gmail.com> wrote:

Hello.

I have an AMI/Rowe TI-1 with a 50 watt hybrid power amp. Is it

possible to modify the amplifier to use either 4 or 8 ohm speakers,

instead of 10 and 15 ohm ones?

Thanks

Joe

Check the way the woofers are wired, many ROWE jukes used 2 x 16 ohm

Woofers in parallel, this would give an impedance of 8 ohm across the

amplifier rather

than 16.

Are you planning on replacing the existing speakers or adding

extension speakers in addition to the ones that are in it ?

Note that the total output of the amp is 22.5w per channel and you

must not exceed this.

Hello.

I have an AMI/Rowe TI-1 with a 50 watt hybrid power amp. Is it

possible to modify the amplifier to use either 4 or 8 ohm speakers,

instead of 10 and 15 ohm ones?

Thanks

Joe

Check the way the woofers are wired, many ROWE jukes used 2 x 16 ohm

Woofers in parallel, this would give an impedance of 8 ohm across the

amplifier rather

than 16.

Are you planning on replacing the existing speakers or adding

extension speakers in addition to the ones that are in it ?

Note that the total output of the amp is 22.5w per channel and you

must not exceed this.

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