[Harp-L] Re: National amp speaker help needed

["Jim Rossen" <jimjimdr@xxxxxxxxx>]

Don't know if you are asking for the name of a tech or also info about the
amp problem.  If the latter....
First concern is if the speaker is a permanent magnet or field coil
speaker.  If there are three wires going from the chassis to the transformer
it is permanent and if there are more (say 4 or 5) it is a field coil.   It
is probably a permanent mag speaker which is the common type and easy to
replace.  Replacement of a field coil speaker is not a home job for most
people.
It is not neccessary to replace both the tranny and speaker unless they are
both bad.  If the transformer or speaker is good, they can be separated.
The tranformer can be mounted on the cabinet side or possibly remounted on
the speaker, depending on the speaker design.  There is no need for the
transfomer to be in close proximity to the speaker.
Another concern is the impedance of the speaker, as you will want to replace
it with one that has the same impedance.  Some speakers are labeled with the
impedance.  If the speaker voice coil is good, the impedance can be
determined by disconnecting the wires from the transformer to the speaker
and measuring the resistance between the speaker terminals with a
multimeter.  The resistance will be about 2/3 of the speaker impedance.
Your amp probably has a 8 or 4 ohm speaker.  If the resistance is not
between 2 and 7, then the speaker voice coil is probably bad and the
measurement will not be useful.
I have been happy with alnico magnet speakers from Weber VST (
www.tedweber.com) for amps like yours.  Consider a 10A100 or Alnico
Signature 10, either with H dust cap, which reduces brightness.
I have not used Kendrick, but they have a mixed reputation on two amp boards
I follow.

Jim R










Bob said-

I have an old National amp that was built by Valco, (Valco 51) that I was
using for harp and it sounded great. It has 2 6V6 power tubes and an
original 10" speaker with the transformer attached. It quit working and I
had an amp tech check it out and replace the tubes and check the circuits.
He tells me that the speaker/transformer must of went out. My question is
where or who can I contact to get a good speaker to replace the old one
with? Such a great amp for harp needs to be kept working and I need to know
who can help me. I'm in the San Antonio, Texas area so if there is someone
close to the area that works on these older vintage amps that would be great
also. Thanks in advance for the knowledge on this list.

Bob "The Captain" Boyd
www.texastide.com
210-494-1118