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

USSEnterprise
04.04.2011 - 04:44
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


Rob in NYC
04.04.2011 - 06:45
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. 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
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.




Rob in NYC
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.


kreed
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.






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