Re: Dynaco FM-3 update/upgrade Pt 2


John Carpanini
 

Hi Tom,

V72 a 12AX7 is the audio output tube and will probably have the most significant influence on the sound. An RCA Command black plate is nice and CBS/Hytron also works well.

Regards,
JohnC

Just out of curiosity, which tubes affect the audio?

Tom R

-----Original Message-----
From: "johnacarp" <jacarp@...>
Sender: FMtuners@yahoogroups.com
Date: Sun, 02 Oct 2011 18:23:42
To: <FMtuners@yahoogroups.com>
Reply-To: FMtuners@yahoogroups.com
Subject: [FMtuners] Re: Dynaco FM-3 update/upgrade Pt 2

Hi Ron,

Looks like you're making great progress.

I wouldn't rush to judgment on the sound, especially the bass, until the power supply caps are in place and have some hours on them.

Also, if you're playing with poly propylenes don't discount the Panasonic ECW series, now available at Mouser.

Regards
JohnC



--- In FMtuners@yahoogroups.com, "r.tom49" <tom_r@> wrote:

Since it's kind of cold and ugly outside today I thought I would post
some observations/issues on my progress. Rather than continuing with the
already long thread:

http://tech.groups.yahoo.com/group/FMtuners/message/68407

I thought I would start a new thread. Here is what I have completed so
far:

* C26 - replaced with Solen PPM to match the original value

* C29, C31 - replaced with Solen PPE to match the original value

* C82, C83 - replaced with Solen PPE with value upgraded to 1.0uF
from 0.1uF

* R11, R13 - replaced with 10k 3w 5% Vishay metal film resistors

* Replaced PEC 1 & 2 on PC 12 (MPX Board) and the PEC on PC 8 (IF
Board) with home brew PEC boards to match the design and parts values as
provided by David Berning (pg 52 of Audio Amateur 02/88) using Miconics
silver mica caps and Vishay metal film resistors
* add an F connector for the antenna

Here's what I still have for parts but not yet installed:

* Replace the metal can cap (C32) with the power supply board from
SDS and parts as suggested by SDS


* C24, C25 - bought Miconics silver mica caps to match the original
value but haven't installed yet (actually forgot to while I had C26 and
the PEC board removed)


* R81-R84 - replace with a matched set of Draloric .25% metal film
resisters
* EIC-320-C7 power cord
* Gold plated RCA's
Currently the Solen caps/R11 R13 resistors have about 150 hrs on them
and the PEC boards about 50. I have not yet aligned the tuner as the
reception was excellent before I started and still is. The FM-3 tuner
was initially tested in my second system consisting of Archer (Rat
Shack) powered antenna, Parasound Halo P3 preamp, Bryston 3B-ST amp, and
B&W matrix 804 speakers, with the following observations:


* The Solen cap installation took care of the boomy bass that the
tuner suffered from but the highs were still somewhat rolled off and
veiled

* The bass sounded pretty deep and natural, however the speakers are
not in an ideal location due to being close to the back wall and one
corner

* The PEC upgrade gave life to the highs which were now more extended
and clear

* Midrange sounded great

Now time to try the Tuner in my main system with the 2 channel portion
consisting of Magnum Dynalab ST2 antenna, Krell Showcase
preamp/processor, Krell KSA-200s amp, Alon model II speakers, 2 x
Paradigm subwoofers, with the following observations:


* The bass was there but thin and seemed to be at the back of the
sound stage
* Occasionally some boomy bass was noticed (example: So Lonely by
The Police)
* Midrange sounded great
* Highs were clear and sweet
* There was some ssssssing evident on spoken S's from the female DJ
which I think was more of a station issue than tuner issue, however it's
not really noticeable with my DBX TX-3 or my Arcam Alpha 8
-After I installed C26 I noticed that Solen recommends it as a bypass
cap, should I be changing it to something else?
-I was originally going to install Auricap caps but the sudden demise of
another component put an end to that. Will it help the bass if I replace
C82, C83 with Auricap caps and maybe up the value to 1.5uF (and it's
less costly than the 1.0uF?
-Will the power supply upgrade help the bass? The sound from the B&W's
tells me it's there somewhere, I just need to find it and bring it
forward.
-Will an alignment help/affect the audio

Thanks for all the help so far, and any further help or suggestions are
greatly appreciated.

Tom

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