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Discussion Starter · #1 ·
Wood Musical instrument Rectangle Electronic instrument Audio equipment

Local shop item in for a service which means cleaning all contact points(pots, jacks, switches, tube pins and sockets) and checking all solder points and wiring for breakdowns.

Client says it is a 65(I dont confirm yet) with "field resistors"(?) changed by an earlier tech to "increase the highs"(?). Pics and observations will be provided: it is always challenging to use/teach proper terminology when servicing an amp for someone who plays lots yet has no interest in workings other than results "by ear".

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Nice amp! That 5U4 might not be a great option due to the extra current requirements for the filament. 3A vs 2A of the 5AR4 is significant especially where vintage power transformers are concerned....that baby is probably getting toasty!:oops:
Also, I'll never understand why folks install 5 watt 470ohm resistors in these amps. 1 watt is what it's spec'd for. If the screens short, it will take a 1 watt out, probably not a 5 watt with potentially stressful results.
 

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That's a '65 all right- transformer dates and tube chart OL date stamp and ink colour line up. Looking forward to seeing more of this beauty!
speaking of tube chart, is this a 12AX7 or a 7025 preamp?

Also, does anyone have power supply ripple figures on these things? I'm just curious... Like, x Vpeak-peak on this supply cap, y Vp-p on the next, etc...
 

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speaking of tube chart, is this a 12AX7 or a 7025 preamp?

Also, does anyone have power supply ripple figures on these things? I'm just curious... Like, x Vpeak-peak on this supply cap, y Vp-p on the next, etc...
V1 and V2 are both 7025. Which are 12AX7A’s I believe.
 

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Discussion Starter · #11 ·
The questionable 1500R grid leak is just fine at 1630R and all the blue moldeds also wonderful no leakage as usual for them....

Amp sounds great and the 5U4 concern, which is warranted(3 amp draw on the 5 volt supply instead of 2 amp of the suggested 5AR4), is changed to a 5AR4(GZ34) as shown on the diagram(s): the 25 volt drop/sag on the 5AR4 instead of the 50v of the 5U4 also livened the amp up a bit🙂

Plugging the amp into a new Celestion G12M cream 8 ohm and it became a much louder defined delivery system with more response from dial tone tweaks..big punchy bass, richer mids and clearer throughout the dials.

I lean toward agreement about the 5 watters installed...I will discuss with the owner(via joes music) and replace if requested...hopefully sell the guy a speaker too😊
 

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I lean toward agreement about the 5 watters installed...I will discuss with the owner(via joes music) and replace if requested...hopefully sell the guy a speaker too😊
I've found EH 6V6's have a tendency to fail in a specific fashion. I couldn't tell you how many I've replaced in DR's but it's several. They usually take out the screen resistor when they let go...IMHO it's a proactive fix.:)
 

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Discussion Starter · #14 ·
one of our members, silently by pm, reminds me that robinette and wayne of headstrong both feel the 1 watt 470R screen resistors were under rated by Leo(maybe ok when 115 was the wall voltage a different situation existed) and at todays 125 supply they should be at least 3 watt.
🤔
 

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one of our members, silently by pm, reminds me that robinette and wayne of headstrong both feel the 1 watt 470R screen resistors were under rated by Leo(maybe ok when 115 was the wall voltage a different situation existed) and at todays 125 supply they should be at least 3 watt.
🤔
If you consider that those 1 watt resistors have lasted decades in most cases....and that they're carbon comp no less, I'd to beg to differ. That said, when I get vintage Fenders in and the screen resistors are way off spec., I usually replace with 2 watt. Never had a problem so far....:)
 

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one of our members, silently by pm, reminds me that robinette and wayne of headstrong both feel the 1 watt 470R screen resistors were under rated by Leo(maybe ok when 115 was the wall voltage a different situation existed) and at todays 125 supply they should be at least 3 watt.
🤔
That’s why you get one of these Brownboxes and set the voltage to whatever you need without modding the amp (thanks @terminalvertigo for the suggestion). I like 115volts for tweed/brownface (even though the tube chart says 110).

It does in fact change the tone of every vintage Fender/Gibson I’ve tried so far (110-115v sounds more mellow, less aggressive and more quiet at the same volumes).

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I tried a bunch of speakers in my ‘64 Deluxe Reverb… I wanted more volume and a balanced punchy tone… the Deluxe has less gain than the Reverb model… so perhaps even better to bump it up. There’s a “chart” on the Gear Page where they poll folks with the question… “best speaker for a Deluxe Reverb?” The Eminence Alessandro won… I bought one from Q Components (a great shop that ships really fast!) and it was around $200. The GP doesn’t lie… superb in my ‘64!
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I tried a bunch of speakers in my ‘64 Deluxe Reverb… I wanted more volume and a balanced punchy tone… the Deluxe has less gain than the Reverb model… so perhaps even better to bump it up. There’s a “chart” on the Gear Page where they poll folks with the question… “best speaker for a Deluxe Reverb?” The Eminence Alessandro won… I bought one from Q Components (a great shop that ships really fast!) and it was around $200. The GP doesn’t lie… superb in my ‘64!
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Great amp! Sold that very amp for a customer of mine. The late '63 and earlier '64 no-logo's are actually slightly different sounding than the later BF's. Very desirable amp!:)
 

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Discussion Starter · #19 ·
I tried a bunch of speakers in my ‘64 Deluxe Reverb… I wanted more volume and a balanced punchy tone… the Deluxe has less gain than the Reverb model… so perhaps even better to bump it up. There’s a “chart” on the Gear Page where they poll folks with the question… “best speaker for a Deluxe Reverb?” The Eminence Alessandro won… I bought one from Q Components (a great shop that ships really fast!) and it was around $200. The GP doesn’t lie… superb in my ‘64!
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Yes that speaker which was stock in my Headstrong Corduroy was impressive; both nextgen and q are always super quick shipping with competative pricing.
 
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