# A peek inside a 65 blackface Deluxe Amp



## Alan Small (Dec 30, 2019)

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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## RBlakeney (Mar 12, 2017)

I have one of these, nice amps!
edit: I also don’t know what a field resistor is.


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## gtrguy (Jul 6, 2006)

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!


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## Alan Small (Dec 30, 2019)

Almost all original beauty...two replaced caps under the doghouse "power cap cover"; screen resistors now 5 watt; one grid leak 1500 appears overheated


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## gbomb (Oct 18, 2013)

December 65' according to tube chart


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## nonreverb (Sep 19, 2006)

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!
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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## Lincoln (Jun 2, 2008)

Thank you @Alan Small for the detailed pictures of an original amp.


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## 2N1305 (Nov 2, 2009)

gtrguy said:


> 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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## Always12AM (Sep 2, 2018)

2N1305 said:


> 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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## butterknucket (Feb 5, 2006)

Yeah, according to the OL on the tube chart, it's a December 1965.


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## Alan Small (Dec 30, 2019)

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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## nonreverb (Sep 19, 2006)

Alan Small said:


> 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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## WCGill (Mar 27, 2009)

I did an earlier Filmosound conversion to the Deluxe, the controls and voltages determining the final circuit. I couldn't believe how loud and clean it was, totally unexpected. Thanks for the peek.


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## Alan Small (Dec 30, 2019)

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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## nonreverb (Sep 19, 2006)

Alan Small said:


> 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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## GuitarTalk (Dec 25, 2018)

Alan Small said:


> 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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## bluehugh2 (Mar 10, 2006)

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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## nonreverb (Sep 19, 2006)

bluehugh2 said:


> 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!
> View attachment 449912
> 
> View attachment 449911
> ...


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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## Alan Small (Dec 30, 2019)

bluehugh2 said:


> 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!
> View attachment 449912
> 
> View attachment 449911
> ...


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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## gbomb (Oct 18, 2013)

I got this gem of a speaker from Mr. Small and it makes my 65 deluxe reverb shine. Jupiter permanent magnet alnico 50 watt.


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## nonreverb (Sep 19, 2006)

gbomb said:


> I got this gem of a speaker from Mr. Small and it makes my 65 deluxe reverb shine. Jupiter permanent magnet alnico 50 watt.
> View attachment 449937


I think this calls for a new thread! What speaker do you prefer in your Deeeeluxe Reverb?


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## Alan Small (Dec 30, 2019)

Client had requested 1 watt 470R screen resistors, .1 coupling cap in the first vibrato channel gain stage and two remaining power caps changed out...the coupling cap will probably reduce the noise on the vibrato channel volume pot and the remaining fresh caps may solidify the feel of the amp in general.
Will bag up the old parts to stay with the amp and use comp resistors, F&T lytics and sozo coupling cap


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## Alan Small (Dec 30, 2019)

After the f&t power cap install all the background noise when turning the volume pot is eliminated....one of the old EH 6v6 had overheated at some point to cook the blue printing to grey....new set tung sol matched set 6v6gt and biased with output transformer resistance method(maths involved ala mr. robinette)😉
Very happy amp now....picking up 1 watt 470r tomorrow morning and job done as requested


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## epis (Feb 25, 2012)

Sorry to rain on your parade, but adjusting negative bias voltage is not proper way to adjust bias current.
New tubes are different than old stock and most likely that -35volts doesn't really follow requirement for bias current.
It might work but I would prefer to measure bias current.


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## Alan Small (Dec 30, 2019)

epis said:


> Sorry to rain on your parade, but adjusting negative bias voltage is not proper way to adjust bias current.
> New tubes are different than old stock and most likely that -35volts doesn't really follow requirement for bias current.
> It might work but I would prefer to measure bias current.


Gotcha loud n clear. Thanks


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## Paul Running (Apr 12, 2020)

Years ago I built a plate current fixture to allow the monitoring of octal, pin 3 plates. I used an analog meter from a defunct VTVM and calibrated it for 100mA full scale deflection or FSD, through selection of the correct shunt resistor for 100mA FSD...custom made.
It has a switched, dual adapter interface that enables me to conveniently monitor a dual output configuration.
It is a low cost test fixture if you can scrounge up the parts.


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## Alan Small (Dec 30, 2019)

Paul Running said:


> Years ago I built a plate current fixture to allow the monitoring of octal, pin 3 plates. I used an analog meter from a defunct VTVM and calibrated it for 100mA full scale deflection or FSD, through selection of the correct shunt resistor for 100mA FSD...custom made.
> It has a switched, dual adapter interface that enables me to conveniently monitor a dual output configuration.
> It is a low cost test fixture if you can scrounge up the parts.
> 
> View attachment 450397


Very cool....i was reading about this type of contraption recently: the author had used two or three hand held meters in unison to achieve the result until he built similar...I used to have a simple store bought version called a BiasKing ? once..not sure where it went🤪
thanks Paul


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