Richard Knoppow wrote:
----- Original Message ----- From: "Garey Barrell" <[email protected]>
To: "drakelist" <[email protected]>
Sent: Friday, April 01, 2011 7:13 AM
Subject: Re: [Drakelist] My R-4B audio?
Lee -
I rarely turn mine above 11 o'clock. What speaker are you using??
The amplifier is designed for a 4 ohm speaker. An 8 ohm speaker (MUCH
more common these days) will reduce the overall output.
Try bridging C176. A high ESR (dried out) cap here will reduce the
gain of the stage considerably. Also verify approximately 4.5 VDC on
the Cathode (Pin 1) of V7.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
I don't agree with this. The level produced by a speaker has more
to do with its design, size of magnet, etc, than its nominal
impedance. I have both 4 and 8 ohm speakers here, the loudest is an 8
ohm speaker probably for a Hammarlund receiver. I have a couple of 4
ohm speakers which are not so loud on the R4 or on a Collins R-388
which also has a nominal 4 ohm ouput. Curiously enough Collins
speakers are 8 ohms. With the Hammarlund speaker the volume control is
around 10 or 11 O'clock, for some other speakers it must be around 2
O'clock. If yours needs to be higher it may indicate either a bad
speaker or some audio problem. I would also check with known good
headphones.
Richard -
I don't agree with THIS!! :-) Granted, there are considerable variations in speaker efficiency
related to all the factors you mentioned and more. BUT, if you have an amplifier with an output
matched to a 4 ohm load, and hang an 8 ohm speaker on it, the speaker efficiency will be less due to
mismatch, _all else being equivalent_!! This is even more important with solid state amps because
of the current operated nature of these.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
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