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Help needed - Pre-amp Tube advice for a Blackface Deluxe

blueswah

Gold Supporting Member
Messages
580
Help needed - Pre-amp Tube advice for a Blackface Deluxe

I've been around a couple of blocks regarding pre-amp tubes but always in relation to a specific amp.

Just wondering what (if any) is a classic pre-amp tube configuration for a BF Deluxe. Thinking NOS tubes or decent used.....

Right now it's a got a mish mash of newer 'junk' pre-amp tubes, sovtek, mesa (chinese), a couple of unknowns, etc etc.

Any help would be appreciated.
 

Oatie

Member
Messages
2,187
Help needed - Pre-amp Tube advice for a Blackface Deluxe

I've been around a couple of blocks regarding pre-amp tubes but always in relation to a specific amp.

Just wondering what (if any) is a classic pre-amp tube configuration for a BF Deluxe. Thinking NOS tubes or decent used.....

Right now it's a got a mish mash of newer 'junk' pre-amp tubes, sovtek, mesa (chinese), a couple of unknowns, etc etc.

Any help would be appreciated.
____________

The original tubes in my 1964 Deluxe are the following:

V1 & V2 RCA 7025
V3 Mullard 12AX7A
V4 (Phase Inverter) RCA 12AT7
Fender used the best dual getter GTA power tubes.
V5 & V6 RCA 6V6GTA Power Tubes (14 watts each)

(6V6GT=12 watts each and are single getter)
The RCA Power Tubes are some of the best ever made.

V7 Bugle Boy or Mullard GZ34 / 5AR4 Rectifier

The old, original Mullard GZ34 will last a lifetime of
home playing. A real NOS set of the RCA 6V6GTA tubes will last 8000
hours easily with the proper bias setting.


I would try to find three RCA 7025 tubes,
Get The Mullard 12AT7 CV4024 on ebay for 28.00 each,
the best phase Inverter tube you can get,
these tubes were the last great made at The Blackburn factory
circa 1985 builds.

http://www.ebay.com/itm/360468237770


 

Jonny D

Member
Messages
1,283
If you are not wanting to spend arms or legs, new stock Electro-Harmonix or JJ tubes sound quite nice in there.

That way you can keep your firstborn child
 

straightblues

Member
Messages
9,685
It depends on what you wan the amp to do. Do you want earlier or later breakup? Do you want more or less gain? Do you want to add a bit of British overtones? What type of music do you play? What speaker are you using?. Answer these questions and we can give you some better recommendations.
 

blueswah

Gold Supporting Member
Messages
580
Thanks for the insights/ suggestions.
What's the difference between a 7025 and a 12AX7?
I see the two used interchangeably (along with ECC83)
 

straightblues

Member
Messages
9,685
They are interchangeable. Generally, the British tended to use ECC83 and the American used 12ax7's. 7025 is the "hi fi" low noise version of the 12AX7. These tubes have a gain factor of 100. They are the highest gain preamp tubes. If you want more headroom, you can replace them with lower gain tubes. See the link below for gain of each preamp tube type.

http://thetubestore.com/gainfactor.html
 

blueswah

Gold Supporting Member
Messages
580
So a 7025 is a 12AX7 that tested to be of a higher quality meaning it's simply a quieter/ low noise 12AX7?

Thanks of the link to the gain chart. I'm familiar with the different gain levels but it's appreciated.

Fwiw I've used various brands of pre-amp tubes in other amps (including the 5751) but I'm not all that familiar with what originally came with BF Deluxes.
Certainly open to suggestions for using non original tubes.
A few state to use RCA 7025 / 12AX7's.
But which one, black plate, gray plate, and which years are considered better/ best?
 

ozspawn

Member
Messages
345
But which one, black plate, gray plate, and which years are considered better/ best?
My favorite - and the one I use in all my Fender amps - is
the RCA long blackplate "cleartop" 7025. They sound similar
to a regular blackplate, but seem to have a bit more "color".

Works for me.
 






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