Audioromy FU29 improvement and upgrades? - diyAudio
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Old 16th March 2012, 02:04 PM   #1
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Default Audioromy FU29 improvement and upgrades?

Hi!

I got my Audioromy FU29 from a friend for about $250. It have ran 6-700hours now and it got the original china tubes installed.

The sound is nice and "full", decent dynamics but far from SE-performance. It's now running a pair of Tannoy 607 markII series(from '92-'94-ish) with a decent result. A little "boxy" bass if you play music with powerful bass like hip-hop and such(not so often that happens anymore..), but overall the soundstage in my impression is pleasant to my ears.

Sound is pretty good, but far from perfect. So, in the true diyaudio-spirit:

How to make the Audioromy FU29 improve performance and sound quality?
*It is unmodified in it's current state.

*While waiting for the FU29 I ordered a pair of GU-29 tubes from Russia, highest military grade, came from the same box, same manifacturing date etc. Price ended up at $13,10 including shipping for the pair.

*Issues with my level pot(gain level) so that I cannot use more than 6-7steps on the pot to play music and a max of about 11'o clock on the pot for max levels due to distortion etc.
Discussing this issue with fotios led to the idea to just de-solder the pot and bypass it completely with wires= I get a power-amp that need a pre-amp on every input?. For me that is no problem. I got a modified Yaquin MS-12B pre-amp for the task.

GU29 russian tubes:
Click the image to open in full size. and the box: Click the image to open in full size.

Can the "paper-in-oil" russian caps be used for something? Leftovers after preamp mods.

Click the image to open in full size.

They replaced these in preamp:


Click the image to open in full size.


I will try to get the schematic for the Audioromy and post it. My idea with this thread is to share, learn and quality-control of modifications.

As things progress I will start on the project and take a lot of pictures, before and after.


Have a nice day..

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Old 16th March 2012, 03:05 PM   #2
piero7 is offline piero7  Italy
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I've changed tube with the USSR ones, remake the power supply with a new one, include the filaments power supply to reduce hum
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Old 16th March 2012, 03:23 PM   #3
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Quote:
Originally Posted by piero7 View Post
I've changed tube with the USSR ones, remake the power supply with a new one, include the filaments power supply to reduce hum
Thanks for your input.

What is the required specs for the new power supply? How was the results?

Is there any changes needed for the driver tubes?

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Old 16th March 2012, 03:31 PM   #4
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I'd be interested to see the schematics, I nearly bought one of these but wasn't brave enough
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Old 16th March 2012, 08:13 PM   #5
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Measured input resistance acc. to this diagram fotis provided(thanks!)

Measuring results:

Unplugged signal cable, unplugged main power direct measure from rca contact. Did NOT unplug speakers.

Ohm-setting: 200k

steps from left:
1-12= 92,2kohm
13-15= 92,1
16=92,0
17=91,9
18=91,8
19=91,6
20=91,5
21=91,3
22=91,1
23=90,9
24=90,4
25=89,7
26=89,0
27=88,1
28=87,1
29=86,1
30=85,2
31=84,0
32=82,9
33=81,6
34=80,2
35=79,5
36-38=79,2
Stop

How accurate my results are is unknown, it is a cheap type digital multimeter.

I will have to learn about calculating gain structure..

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File Type: jpg audioromy fu-29 pot Z.jpg (60.8 KB, 697 views)
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Old 16th March 2012, 09:25 PM   #6
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Challenged my Excel-skills.. A better presentation of the numbers posted above.
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File Type: jpg Audioromy pot reading.jpg (37.3 KB, 158 views)
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Old 16th March 2012, 09:29 PM   #7
piero7 is offline piero7  Italy
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here the schematic
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File Type: gif fu29.gif (68.1 KB, 452 views)
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Old 16th March 2012, 09:31 PM   #8
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Quote:
Originally Posted by piero7 View Post
here the schematic
Thank you piero7!

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Last edited by Join; 16th March 2012 at 09:51 PM.
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Old 16th March 2012, 09:55 PM   #9
fotios is offline fotios  Greece
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Hi guys

Schematic that posted "piero7" is right, i also found the same. But is not so clear.
Any way, the input potentiometer is by sure a 2 X 100K log according the measurements of "Join".

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Last edited by fotios; 16th March 2012 at 10:03 PM.
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Old 16th March 2012, 10:08 PM   #10
fotios is offline fotios  Greece
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Quote:
Originally Posted by piero7 View Post
I've changed tube with the USSR ones, remake the power supply with a new one, include the filaments power supply to reduce hum
Attention: OTP

Hey Piero7, i think that i remember you from other thread:
Remote Control Kits of Mr. Mikkel Simonsen.

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Last edited by fotios; 16th March 2012 at 10:12 PM.
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