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Posted: Tue Aug 17, 2010 6:44 pm
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I don't own any Webers but I've installed plenty into customers' amps. Their alnicos are superb, the ceramics sound like raw azz. The Cali's sound good but nothing like the JBL's they purport to emulate.

Arjay

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Posted: Tue Aug 17, 2010 7:59 pm
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Webers, IMO, take quite a while to breakin(over 20hrs), before you really get to hear the goods. Had a ceramic 10F-150T(light dope) in a 2X10 conversion '68 Bassman combo, with an old Naylor 10-40. Any way after a couple months, one night I played the amp and hot damn it really started to bloom. Had to check the guitar and amp settings, nothing had changed. The speaker just came into it's zone ! Since then I've R&R the Naylor for another 10F, but it's just a sprout. I've had great results from Chicago's, California's, 10F's and the 10" alnicos. What I like about these Weber speakers is that they perform very much like their discriptions from the web site. Art

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Posted: Tue Aug 17, 2010 8:41 pm
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+1 on the alnico Chicago's.

They're about as close as one can get to a vintage P12Q without paying robber baron prices for the real McCoy, at least after a suitable break-in period.

I put a pair of 12A150's into a buddy's 69 Pro Reverb (replacing the exhausted OEM Utah pie tins) and that amp positively sang.

(I'm still trying to con it out of him)

:mrgreen:

Arjay

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Posted: Wed Aug 18, 2010 6:04 am
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Webers do have a considerable break in time,the '66 Pro Reverb I own had Utah speakers,man they sounded bad,and the Webers were a huge improvement.
I do favor the alnicos now after hearing what one can do in one of my amps,I'm thinking of putting another one in a '66 Deluxe Reverb.


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Posted: Wed Aug 18, 2010 7:11 am
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I cringe every time I open up a customer's amp to find those orange-label Utah's inside.

Absolutely no redeeming social value!

Arjay

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Posted: Wed Aug 18, 2010 4:00 pm
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Wow...lots of info...)

I have a very limited budget so I will probably have to do the work on this over a long period of time. Can get new P10's for $90, re-coned for $45 each (although one company quoted $175 each just to re-cone).

Recommendations for cap kits? Trying to determine which capacitors it needs and if our local distributor might carry replacements.

I don't want a fresh charge so will not plug in the amp until caps are replaced and a new 3 prong grounded pigtail ready to go.

You folks are awesome...thanks for the help.


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Posted: Wed Aug 18, 2010 10:11 pm
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Can you verify the amp circuit model, ie 5F6 or 5F6-A. It should be on the tube chart located inside the cabinet. If it is either of these, there is another capacitor that should be removed off the standby switch to ground. My oversight ! I haven't looked at one of these schematics for a while. At any rate you're looking at (4)20uf/500-600volt; 8uf/450volt; 2uf/150volt; 8uf/150 for the power supply cap job. Art

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Posted: Wed Aug 18, 2010 10:21 pm
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aclempoppi wrote:
Can you verify the amp circuit model, ie 5F6 or 5F6-A. It should be on the tube chart located inside the cabinet.


+1

If in doubt or the tube chart is missing/damaged, check the first tube at the extreme left of the chassis (as viewed from the rear).

If that first bottle is a GZ34 then the amp is a 5F6-A. The earlier 5F6 uses a mercury-vapor Type 83 rectifier tube -- use caution when handling it and treat it as haz-mat if it becomes necessary to dispose of it.

HTH

Arjay

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Posted: Thu Aug 19, 2010 5:37 am
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There's a website... www.schematicheaven.com
that will have the layout and wiring schematic if you need that for reference also.


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Posted: Thu Aug 19, 2010 6:32 am
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There is an inside label that says 5F6-A and the serial number that matches what is stamped under the fuse holder on the top plate.


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Posted: Thu Aug 19, 2010 9:17 am
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apoorstudio wrote:
There is an inside label that says 5F6-A and the serial number that matches what is stamped under the fuse holder on the top plate.


The -A variant is the preferred tweed Bassman. Replacement parts and tubes are readily available to keep this warrior road-worthy for the next millenium and here's how I would treat it if the amp were mine.

Have the chassis inspected by a competent amp tech who is familiar with the tweed architecture. Safety and reliability should be the primary considerations. Replace and/or repair anything that looks wonky then have a new set of tubes installed, preferably vintage NOS glass. Save all of the original removed parts.

Re-cone the original speakers to spec -- all of them. Weber does a fine job with the vintage P10Qs or you might take them to a trustworty local shop if you have one available.

Set the original cabinet aside (save it for "posterity") and have a new reproduction cab built. There are several commercial outfits that fabricate vintage-style tweed enclosures (Mojotone, JD Newell, Green Eagle Amplification, etc).

This can all be compartmentalized so as to be performed in stages to take some of the "bite" out of the economic outlay (start with the chassis overhaul though).

JMO

Arjay

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Posted: Sat Aug 21, 2010 1:25 am
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I'm going to second guess myself on the .05uf/600 cap off the standby switch. This cap is supposed to minimize the switching sudden effect, or the abrupt in-rush when the switch is thrown "on". This design, along with healthy screen resistors and a chassis AC ground scenario, should be fine. We kind of went over this with CB's super. Stratele and CB, where are you guys ? I could use your help here ! Art

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Posted: Sat Aug 21, 2010 6:32 am
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The main filter caps on this amp are four 20 mfd/600VDC rated. I haven't found those high voltage 'lytics. I was taught to run two 100 mfd/350 VDC lytics in series to replace the FIRST parallel pair of 20 mfd/600 VDC caps in these amps off the rectifier. You get 50 mfd total capacitance rated at total 700VDC to replace the two 20mfd cap (=40 mfd total filtering). Just be sure to place a resistor across each 100 mfd/350 VDC cap, to distribute the voltage equally. I use a 220 K-ohm, 2 watt across each replacement cap.

For the other two 20 mfd/600 VDC filter caps, it's not as critical to have 600 VDC rating. Though prolly best to use perhaps two 50 mfd/350 VDC rated caps in series for EACH 20mfd/600 VDC cap, if they will fit. Same resistor across each replacement cap to distribute the load. Otherwise, I believe that I used 20 mfd/500 VDC rated filter caps for the last two portions of the main filter circuit without issues.


Changing ALL the 'lytics is prolly a good idea. Go up in voltage rating if you can, as today's outlet voltage is usually a good 10-15% higher than when the amp was made. I run up all new lytics with a Variac.

You may find replacing the bypass cap across the 12AY7 cathode resistor will boost the tone back to original. This cap is usually a dried out OEM part. And checking all cathode and anode tied resistors for > 20% drifting. All that should hopefully make for a reliable amp. It certainly is a classic.

http://www.kbapps.com/audio/schematics/ ... n5f6a.html


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Posted: Sat Aug 21, 2010 4:00 pm
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Looked at caps here in town...20uf/600 could not find available...ordered one from Weber for $2.00...$8.00 shipping...

10uf/250 for $1.50 (x2) and 2mf/150 for $1.00...

Another online source showed beeswax caps but want $100 each! eeeek

At this point just want it to work well and safely...will worry about restoring as funds are more readily available...

Is there a recommended place to ground the pigtail? Am assuming a chassis ground is good.

Thanks again,

Allen


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Posted: Sat Aug 21, 2010 6:04 pm
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Run the "pigtailed" caps to same grounding point as the OEM caps. They sit under the cap cover on a separate breadboard, I believe. One grounding point for the four OEM caps. Pigtail (+) to (-) ends of each new lytic cap. Free (+) end to B+ side and free (-) to ground (you prolly already know this, sorry I had to mention it).

Jupiter Beeswax caps are usually used for "coupling" or signal use (non-polar). My experience with these caps are in vintage high-end h-fi amp restorations. Like old Harmon-Kardon Citation II amps. Or 1950-60's era McIntosh amps. Don't think you need to go to these caps. I'd ONLY replace the OEM coupling, if they were bad. No matter what cap you replace in the signal path, it's going to tend to change the tone. Even, if you use NOS Mallory or "real" Sprague "Mylar" Orange Drops. IMHO.

Oh, I did mention that I ramp up the "new" electrolytic caps with a Variac? Forming them helps, as sometimes 'lytics sold as "new" have sat on a shelf in a warehouse fr a few years. Replace the GZ34 with a direct heated rectifier (like a 5Y3GT) for ramping up the new caps. Speakers connected, no volume, & no guitar plugged in. I usually start at around 70-80 VAC and ramp up in 10 VAC increments every 15-30 minutes. Keep a DVM on the B+ to read VDC as you ramp it up. The B+ should rise corresponding to Variac settings. If not, stop ramping and check fr mis-wiring or bad grounding points.

Hey, good luck with the amp!


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