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fender concert 2 mods

 
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performer



Joined: 19 Sep 2007
Posts: 4

PostPosted: Thu Sep 27, 2007 11:13 am    Post subject: fender concert 2 mods Reply with quote

Hi and greetings from Ireland;

I am new to this excellent site,I wonder if anyone could point me in the right direction to any information about mods to an old 1982 Fender "rivera" Concert.

I must admit that some mods to the tone circuit have already been done,some mods were previously done by Brinsley Schwarz to tone caps i.e the mid,bass and treble and 100k slope resistor ; to .002 600volt spragues /zircon,in clean channel 250pf cap to silver mica 250pf,in overdrive treble cap to silver mica 500pf, 100k slope resistor to 56k 1 watt.

The elecrolytic caps on the cathode circuits for V1 and V2 from right to left to 10ufs x 2 and1uf.
These mod have helped a bit but the amps still a bit dark or hard and the O.D.channel lacks abit of gain and still sounds a bit harsh.
I`d really like both Tweed and Blackface sounds I`d like a valve rectiier in the amp,is it worth doing any more mods to this amp or look elsewhere.

However talking(e-mailing) to Jim Price at Omega Amps he recommended replacing plate resistors with Vishay Dale RN165 and cathodes to metal oxide,all cathode caps to non polarised and have my amp tech "Dumbelise" the driver section.
Question is what does this all mean and how do I go about doing this?,any advice welcome.

Many thanks people,one love.
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oldhousescott



Joined: 15 Apr 2006
Posts: 94
Location: South Carolina

PostPosted: Thu Sep 27, 2007 1:46 pm    Post subject: Reply with quote

Looks like that amp uses a bridge rectifier setup so a single tube rectifier is not a possibility.

To brighten the amp, I would try removing, or at least reducing the value of, the .001uF plate bypass cap on V1. Hopefully it's not needed for stability. You might get a little more hiss without it. If you still lack brightness, I would add a 82-120pF bright cap on the clean channel volume pot.

I'm assuming you meant that the two 10uF cathode bypass caps are on V1 and the clean channel section of V2. This would put the 1uF cap on the dirty channel section of V2. I would leave that as is. I would be tempted to raise the value of the V2A cathode resistor to say 2K7 or higher to get a more pronounced low-shelf cut. You should then be able to turn up the volume and gain pots without as much flubb in the bass.

I'm also assuming you meant the dirty channel caps are 500pF, .022uF and .022uF, not the .002 as you posted. If so, those values are fine, just leave them. You might consider reducing the slope resistor to 33k to get more mids, but it's not necessary. You should be able to get plenty of gain out of the dirty channel.

Different speakers might help, too. Some can sound too dry or dark. Which model do you have, the 1x12, 2x10, or 4x10?

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performer



Joined: 19 Sep 2007
Posts: 4

PostPosted: Thu Sep 27, 2007 2:58 pm    Post subject: concert 2 mods Reply with quote

Hi and greetings

Thanks very much for your help "oldhousescot"it is much appreciated.
With regards to the mods already completed let me explain further as I`m no electronic or amp tech though many times over the last 25 years playing I wish I was!.

According to Brinsley Schwarz(former great guitarist with "Brinsley Schwarz" which included the great Nick Lowe and also with Grahm Parker and The Rumour) mods to tone caps ,two large caps .1uf and .047uf and small 250pf two lage caps changed to .022uf 600 volt spragues or xicons,sprauges in clean channel xicons in dirty channel.
In clean channel 250pf treble cap for silver mica 250pf,100k slope resistor replaced with 56k,1 watt resistor.

The cathode circuits for V1 and V2,the caps are 25/25vlt elecrolytics and resistors are 680 ohm for the right hand one attached to pins 3/8 ofVale 1,and 1k5 for the remaining two,attached to pins 3 and 8 of Valve 2.(phew!)

The eletrolytic caps have ben changed from right to left(amp chassis out power tubes to left,looking down on from right to left) 10uf,10uf and1uf.

And by the way out of interest, :D where or what are plate resistors?,Brinsley included replacement components and written clear instructions with his mods which was of great help to a non amp tech like me.

I note Lee Jackson offers a mod including a variable mid shift,catch is you have to purchase the parts and an instructional DVD as no instructions are included,but is it any good?,any opinions welcome.

Once again many thanks,take care people;one love.
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performer



Joined: 19 Sep 2007
Posts: 4

PostPosted: Thu Sep 27, 2007 3:03 pm    Post subject: concert 2 mods Reply with quote

Hi and greetings

Thanks very much for your help "oldhousescot"it is much appreciated.
With regards to the mods already completed let me explain further as I`m no electronic or amp tech though many times over the last 25 years playing I wish I was!.

According to Brinsley Schwarz(former great guitarist with "Brinsley Schwarz" which included the great Nick Lowe and also with Grahm Parker and The Rumour) mods to tone caps ,two large caps .1uf and .047uf and small 250pf two lage caps changed to .022uf 600 volt spragues or xicons,sprauges in clean channel xicons in dirty channel.
In clean channel 250pf treble cap for silver mica 250pf,100k slope resistor replaced with 56k,1 watt resistor.

The cathode circuits for V1 and V2,the caps are 25/25vlt elecrolytics and resistors are 680 ohm for the right hand one attached to pins 3/8 ofVale 1,and 1k5 for the remaining two,attached to pins 3 and 8 of Valve 2.(phew!)

The eletrolytic caps have ben changed from right to left(amp chassis out power tubes to left,looking down on from right to left) 10uf,10uf and1uf.

And by the way out of interest, :D where or what are plate resistors?,Brinsley included replacement components and written clear instructions with his mods which was of great help to a non amp tech like me.

I note Lee Jackson offers a mod including a variable mid shift,catch is you have to purchase the parts and an instructional DVD as no instructions are included,but is it any good?,any opinions welcome.

Once again many thanks,take care people;one love.

P.S. "oldhousescott" the Concert is a 1 x 12 loaded with Celestion Vintage 30 also sometime use 1 x 12 extension cab with same.
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