Altec amplifier 9440A which input transformer to use

**MerlinVSM** · June 16th, 2012, 01:08 PM

Hi
I dont know which transformers to use in my Altec power amplifier 9440A when would like to use the balanced inputs.
There are several transformers 15335A (, 15336A and 15095A.

http://altecpro.com/pdfs/vintage/Ele...ransformer.pdf

The amplifier to be driven directly by a Behringer DCX2496 crossover output impedance 160ohm at 1kHZ, and
maximum output +22 dBu

Is it just to put the transformers into the power amplifier or do I need to make any cable connections/changes.

Thanks for help.

**Old Guy** · June 16th, 2012, 01:57 PM

15335A is what Altec recommended if memory serves.

**Altec Best** · June 16th, 2012, 02:16 PM

No those transformers are plug-in.They have pins on the bottom and plug right into the amp (Sockets) no cables needed with those.

15335A - Bridging Transformer
15356A - Matching Transformer
15095A -Bridging/Matching Transformer

**MerlinVSM** · June 16th, 2012, 02:31 PM

Originally Posted by Altec Best

No those transformers are plug-in.They have pins on the bottom and plug right into the amp (Sockets) no cables needed with those.

15335A - Bridging Transformer
15356A - Matching Transformer
15095A -Bridging/Matching Transformer

As the output impedance from the Behringer crossover is 150 Ohm I assume it is the 15356A Matching transformer to use and not the 15335A ?Altec transformers.jpg

Please, confirm.

Where to buy these ?

**Old Guy** · June 16th, 2012, 04:24 PM

Originally Posted by MerlinVSM

As the output impedance from the Behringer crossover is 150 Ohm I assume it is the 15356A Matching transformer to use and not the 15335A ?Altec transformers.jpg

Please, confirm.

Where to buy these ?

Someone else please chime in, but in my experience the Behringer drives an upward mismatch without issues. So AFAIK going higher is better than lower...

**aditya** · June 19th, 2012, 12:38 AM

Originally Posted by Old Guy

Someone else please chime in, but in my experience the Behringer drives an upward mismatch without issues. So AFAIK going higher is better than lower...

Yes....OG is right.

The 150 ohms thing of the Behringer is actually "150 ohms and upwards", as the output is not a shunt-loaded type, unlike for example microphones, where the output is actually shunted by a resistive value (of the v/coil or trafo) at the specified impedance. The Behringer spec means that it can take a maximum loading of 150 ohms at its o/p terminals, below which the signal will suffer. So any upward value will be a good thing. This is a standard nature of any of the electronically balanced/unbalanced outputs, and the specified imedance is nothing more than a series resistor at the o/p, to prevent the device output stage from getting fried. So 15335A should be the choice.

@MerlinVSM

The e-bay link provided by AB (Altec Best) has one seller with 3 nos. of 15335As available for sale.

**Altec Best** · June 16th, 2012, 03:01 PM

I would try Ira-Tec for those transformers.He repairs Altec electronics...

Iratec Pro Audio Repair
Oklahoma City, OK
U.S.A.

405-324-5311
[email protected]

**MerlinVSM** · June 16th, 2012, 03:12 PM

Originally Posted by Altec Best

I would try Ira-Tec for those transformers.He repairs Altec electronics...

Iratec Pro Audio Repair
Oklahoma City, OK
U.S.A.

405-324-5311
[email protected]

The Email adress does not work ? Any other email ?

**Altec Best** · June 16th, 2012, 03:16 PM

Great Plains,Iratec,micro-Mikes, these guys are all old school. TELEPHONE ! Or try ebay these transformers come up all the time.In fact they have them all right now I think.I just took a quick lookie...

http://www.ebay.com/sch/i.html?_trks...rmers&_sacat=0