[Feel free to ask Myles]

Many thanks for your advice Myles, I am pretty sure I could not have these advices easily in

netherlands, in fact I would not know where to find a capable technician for these amps.

 

Originally posted by myles111:

 

If your amp has sat unused for a few years, the filter caps in the power supply need to be checked as they probably dried out.

 

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Initially when I switched the amp on, there were a lot of crackles, which made me turn it off and send my post to you.

Now I did switch it on again today and only a few crackles, which were gone within a few minutes.

They did not come back.

Crackles came back as soon as I plugged a guitar, and after some moving a bit of the inputjack to get some possible corrosion off hence crackles gone as well..

The sound is as clear,warm and dynamic as I could remember.

In fact I played last night on a practice with the other guitarists amp, a line6 modular whatever it is, I could not get it sound like I wanted. just cold/metallic sound.

I really thought that I had it wrong (nobody complained, anyway about the sound) but when I am now listening to the concert amp..I can tell you these modular amps don't come even close...

 

So it looks like it just needs some cleaning of pots and cleaning of input contacts like you said

 

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A good tech can check this pretty quickly for you with a capacitor checker. They should also be inspected visually to see if the weep hole has stuff coming out of it, as this is what is supposed to happen when they go bad.

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wright this is something to cheque on

 

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If they are on their way out, this can be checked by having a tech check the noise floor on your amp using a scope. This is pretty easy, it is something we do at the amp clinics as part of our normal routine.

 

Your tubes may be just fine and dandy. Can you write back at some point and tell me what they are?

 

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I think by now they are in great condition.

This is what's written on the tubes by the way;

Fender special design

023556 (30,11,23) ACS

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If they do need replacement, the tubes that sound the most like Fender in the days of Fender in these amps and the earlier 60's blackface amps to most of my clients are the Tung-Sol 5881 NOS tubes. You can get these from Groove Tubes in the USA and Watford Valves in the UK. To keep the amp clean, you want something with a rating the same as about a Groove Tubes #7 rating.

 

If your old tubes are good or if you stick in new ones, be sure to have your bias checked and adjusted if necessary. Your Concert is one of the amps designed by Paul Rivera, and is a pretty strong amp. The best place to start with bias is at about -50 volts.

 

Make sure if you change the output tubes, you also put in a fresh 12AT7 in the phase inverter position. If there is a 12AX7 in there now, somebody changed it, and get rid of it. Make sure to get a balanced or matched phase inverter. This tube is V7 on your tube chart.

there's no tube with 12ax7.

In fact I bought this amp new myselve in 1983 and I never replaced any tube, so it is in original state. (even the control cheque card before it leaves the factory was in it.)

 

V1 and V2 should be 7025's and not 12AX7's.

 

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there is 7025 on most of the preamp tubes. (7x)

I could not read four of them, And I did not

want to pull them out as the amp is fine so far and I could not pull them out without using heavy force, which I like to avoid if not needed.

 

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Spray in all the pots with a good tuner cleaner/lube, not just contact cleaner, or the pots may stick and freeze up.

 

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wright,,, mmm. this means I have to unmount the amp to get there..

as soons as it start's crackling will do that..

thanks.

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Let me know if you need any more help. Let me know how it turned out.

 

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If you are in the Los Angeles area, I would be happy to check your amp and the caps for free at the upcoming amp clinic on May 11th. Details are on my website.

 

I whish I was, but there's a long distance between netherlands and L.A.

 

Regards,[/QB]

Thank's again

Fred

[Feel free to ask Myles]

Hello Miles,

I could not find the answer with the search so I guess the question was not asked yet.

It looks like I will start with some gigging after 20 years of absence..

Now I undusted an old fender concert amp (1983 black faced- 60 watts rms) I still had in a corner.

It probably needs some new tubes.

So my question is what tubes would you recommand for this amp, to get as clean as possible!

(I will use it for jazz so I don't want dirty output )

 

Thanks for advice,

 

Fred