Help! Amps as pre-amps???


Louis Browning
Unregistered guest
Hello, can anyone help me? I have been asked to install a sound system for a common room, running radio, c.d. etc.
All the inputs run through a Cambridge Audio A1 to allow the students to control the volume and source, but the output from the amp needs to run through a mixing desk (a little spirit folio thing) and then to a power amp to drive the speakers. The Mixer IS needed to cap the volume and to allow mic/other inputs to be used by the teaching staff at times.

My problem is that the A1 amp won't allow volume control on the tape out- the output I am using at the moment- which makes it rather pointless. Is there any way of running from the speaker outs on the amp to the mixer without melting anything????

Many thanks to anyone who can help.


Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6500
Registered: May-04

You really can't run from speaker level to line level easily. There are step down transformers that will manage this, but it becomes a bit of a clooged set up. Tape out is a fixed level for reasons of recording and that will be the same for any pre amp you use.

If the location where the students control sources is not too far from the location of the mixer, I would suggest wiring up a simple passive pre amp. Install a simple aluminum project box you can buy at any electrical supply house. Put input jacks on the back of the box which then run to a selector switch and a volume control. From the volume control, the signal goes to a pair of output jacks on the back of the box.

Passive pre amps are not always the best fidelity in all situations, but the faults are probably minimal enough to warrant the use in this situation. If you are not able to build a passive pre amp yourself, there are many companies which manufacturer such products. Depending on the size of the supply house you go to, they might sell a pre assembled package.


Louis Browning
Unregistered guest
Thanks for the advice Jan, it definately looks like something worth looking into.
Unfortunately I have zero budget, everything that I have was bought by some school coucil a couple of months ago (something I didn't know about before I agreed to do the install) and I can't squeeze another penny out of them. Does anyone know of a way to modify the current amp (Cambridge Audio A1) so that the speaker outs can run at line level, or whether I could take the signal out just before it is amplified? It probably can't be done, but you guys seem to know a LOT more than I do about sound!

Thanks again Jan, and thanks in advance for any help!

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