Reconing speakers - When?

This might be a stupid question, but aside from physical damage or
defects, when should this be done?

The reason I'm asking is that on my RO1454, I've had the amp rebuilt,
new tubes (two different matched pairs), new cartridge installed (P51
with a .7mil stylus), and I'm still not 100% happy with the sound
quality.

What I hear is a harshness in the midrange.

So, is this is good as its going to get, or is the next step to recone
the speaker and horn?
(physically, they look good).

Thanks,
Mike

On Jun 29, 4:39*pm, NJ Mike wrote:
This might be a stupid question, but aside from physical damage or
defects, when should this be done?

The reason I'm asking is that on my RO1454, I've had the amp rebuilt,
new tubes (two different matched pairs), new cartridge installed (P51
with a .7mil stylus), and I'm still not 100% happy with the sound
quality.

What I hear is a harshness in the midrange.

So, is this is good as its going to get, or is the next step to recone
the speaker and horn?
(physically, they look good).

Thanks,
Mike

Can you define "harshness"? It over emphasis or outright distortion
such as from an overdriven amplifier. Try this experiment: Start the
machine playing then with volume control down, connect the line/record
output from a cd player, stereo receiver to the input on the RO amp
and turn it up. How does it sound? Assuming that the amp was
properly rebuilt it should sound somewhat bass-y w/recessive highs.
IIRC These machines don't have a full crossover -just a capacitor for
the horn so you'll will notice some "cry" from the woofer as highs are
being fed to it.

Matching output tubes on this sort of amp is pointless as they are not
operated anywhere near their max ratings and the signal from a typical
junk pickup such as a 51 is already somewhat distorted under the best
conditions. Also, do you notice at least some compensation for bass
as the volume control is lowered? These are dual tapped controls and I
have seen cases where some character replaced the pot with whatever
was handy.

You really can't get best performance from a crude ceramic pickup but
the tonearm on these machines is poorly balanced so unless you remove
the finger spring under the arm and add a counterweight to properly
balance it you will have to continue using a ceramic. Try a Pfansteihl
(sp) 132.

I did the counterweight mod on six of these old boxes back in the 80's
and the difference was dramatic. i could now use a Pickering v-15 and
track properly as low as 2 grams. You have to add a preamp for a mag
cartridge but the sound improvement turns the machine from a
noisemaker into something enjoyable.

Rob in NYC

NJ Mike wrote:
This might be a stupid question, but aside from physical damage or
defects, when should this be done?

The reason I'm asking is that on my RO1454, I've had the amp rebuilt,
new tubes (two different matched pairs), new cartridge installed (P51
with a .7mil stylus), and I'm still not 100% happy with the sound
quality.

What I hear is a harshness in the midrange.

So, is this is good as its going to get, or is the next step to recone
the speaker and horn?
(physically, they look good).

Thanks,
Mike

Other things to check. Tap quickly but gently on the speaker cone, if
you can hear a little rattle, the "spider" between the coil and the cone
is broken. Recone.

Also use two or four fingers to push the cone inward and relese it out
as if it was hitting some low bass notes. Push it straight, don't lean
it to one side. If you hear a scratching sound, first make sure you
aren't causing it by pushing to one side. If it is the speaker, the
voice coil is halfway fried, expanded, and rubbing. Recone.

If it checks out OK, well I've fixed supposedly *rebuilt* amps from many
sources. Some of them from a few of the biggest dealers in the states,
some of them just don't test them properly. Many test the amp by
listening to it. Everyones hearing is different so there is no standard
to go by. The proper way is to use a square wave input and look at the
output on a scope.