5F1 Group Build

Transformers: I checked out the Allen Amps website to see if there's anything available that can be used for Tweed Champ build. Would any of the following work?

How about the TP-25H:
Heyboer Upgrade Power Transformer for BF/SF Champ™, VibroChamp™, Bronco™, and Princeton™. 310V-0-310V @ 150ma, 6.3V at 4.5A, 5V at 2A. 50V bias tap, center-tapped heater winding and internal hum shield brought out to a lead for grounding. 2" by 2-1/2" mounting centers, copper flux band, 5.1lbs. Unit is approximately 1" taller than a stock transformer. Supports the use of both 6L6 and EL34 power tubes (with proper socket wiring). Now featuring M-6 grain oriented lamination steel for cooler operation.

TO-11S...?
TO11S Heyboer output transformer rated 4,000 ohms primary to 4 or 8 ohms secondary. It is the same as the above TO11C but mounted on its side the short way to prevent transformer coupled hum. It will now be the standard OT for the 10W Chihuahua. Excellent choice for a 6L6 or EL34 single-ended amp using either a 4 or an 8 ohm speaker load. 3-1/8" mounting centers.

Linky...:

Allen Amplification - Quality Tube Guitar Amps, Kit, Parts, and Repairs

www.allenamps.com
 
Hammond iron is good quality and in the US Hawk electronics is reasonably priced for parts and shipping.
I dont have part numbers on hand.,
Edcor is another viable reasonably priced source for transformers.

Tube Depot is also a good source for most board parts.
I believe the 6n2p (edit typo fixed) has different pinout wiring (4-5) for the heaters if using 6.3v as 12ax7 are 4+5 jumpered, -9.
 
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Hammond OT 1750C seems an appropriate choice, recommended in some other forum threads:

1750C 5,000/8,000 3.2 Single Ended 5 Bobbin (Bronco, AA764, AB764, Blackface, Silverface) (Champ, Tweed, 5C1, 5E1, 5F1, AA764, Blackface, Silverface, Vibro Blackface) (Harvard, 6G
$27.90 at Hawk USA.

Products | Hawk Electronics

www.hawkusa.com www.hawkusa.com

290AX CHAMP* 125P1B, 022772, 66079B 5C1, 5E1, 5F1, Tweed, Blackface, Silverface, AA764 120V, 60 Hz 650/550Vct @ 100 mA 6.3Vct @ 2.25A 5V @3A
290AEX has other input voltage choices

290AX $57.70 at Hawk USA

Products | Hawk Electronics

www.hawkusa.com www.hawkusa.com


These seem to fit the bill but others may have a better handle on iron choices.
I have Hammond iron in my brown princeton 6g2 build, very satisfied, and also for the JCM800 micro 1w I have in progress (again, finally).
 
syscokid said:
Transformers: I checked out the Allen Amps website to see if there's anything available that can be used for Tweed Champ build. Would any of the following work?

How about the TP-25H:
Heyboer Upgrade Power Transformer for BF/SF Champ™, VibroChamp™, Bronco™, and Princeton™. 310V-0-310V @ 150ma, 6.3V at 4.5A, 5V at 2A. 50V bias tap, center-tapped heater winding and internal hum shield brought out to a lead for grounding. 2" by 2-1/2" mounting centers, copper flux band, 5.1lbs. Unit is approximately 1" taller than a stock transformer. Supports the use of both 6L6 and EL34 power tubes (with proper socket wiring). Now featuring M-6 grain oriented lamination steel for cooler operation.

TO-11S...?
TO11S Heyboer output transformer rated 4,000 ohms primary to 4 or 8 ohms secondary. It is the same as the above TO11C but mounted on its side the short way to prevent transformer coupled hum. It will now be the standard OT for the 10W Chihuahua. Excellent choice for a 6L6 or EL34 single-ended amp using either a 4 or an 8 ohm speaker load. 3-1/8" mounting centers.

Linky...:

Allen Amplification - Quality Tube Guitar Amps, Kit, Parts, and Repairs

www.allenamps.com
Click to expand...
The original "tweed" PT had a 650VAC (325-0-325) -/+10% (so a 660VAC is fine) secondary rated at 70mA.

The very earliest Champs used a small "surplus" 17k/3.2 5 ohm 5 watt car radio type OT.
The OT was later changed to the little larger 8k/4 ohm 5 watt OT that is most commonly seen in the tweed 5F1's.

The transformers linked above will definitely work for this type build, just be aware that using "upgrade" transformers changes the characteristics of the amp some.
To use the TO11C or TO11S OT with a 6V6 output tube you would want to miss-match the speaker "up" by 100% so that the 6V6 "sees" the OT primary as an 8k load. So you would use an 8 ohm speaker hooked to the 4 ohm output tap, or a 16 ohm speaker hooked to the 8 ohm output tap.

jtcnj said:
Hammond OT 1750C seems an appropriate choice, recommended in some other forum threads:

1750C 5,000/8,000 3.2 Single Ended 5 Bobbin (Bronco, AA764, AB764, Blackface, Silverface) (Champ, Tweed, 5C1, 5E1, 5F1, AA764, Blackface, Silverface, Vibro Blackface) (Harvard, 6G
$27.90 at Hawk USA.

Products | Hawk Electronics

www.hawkusa.com www.hawkusa.com

290AX CHAMP* 125P1B, 022772, 66079B 5C1, 5E1, 5F1, Tweed, Blackface, Silverface, AA764 120V, 60 Hz 650/550Vct @ 100 mA 6.3Vct @ 2.25A 5V @3A
290AEX has other input voltage choices

290AX $57.70 at Hawk USA

Products | Hawk Electronics

www.hawkusa.com www.hawkusa.com


These seem to fit the bill but others may have a better handle on iron choices.
I have Hammond iron in my brown princeton 6g2 build, very satisfied, and also for the JCM800 micro 1w I have in progress (again, finally).
Click to expand...
Just to add to these Hammond transformer options, if you want an output transformer with a 4 ohm secondary rather than the 3.2 ohm, use the 1760C. It is basically the same transformer as the 1750C except for the secondary impedance.
For the PT, the 290ABX is suitable & features a 120VAC/240VAC primary. Specs are the same as above.
Cheers
 
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I've started sourcing parts and have surpassed $200. I have a chassis, turret board and small head box so that's out of the way. I have only built Marshall style amps so I'm in the wilderness for Fender type transformers. I was looking at Hammond 1760C output and a Hammond 290AX for power. The cost is around $50 and $65, respectively. I only wish ClassicTone was still in business.
 
BTW, what is this amp supposed to sound like? Any recommendations on preamp or power tubes? Also, I only have 16 ohm 4X12 cabs for speakers.
 
Far Rider said:
BTW, what is this amp supposed to sound like? Any recommendations on preamp or power tubes? Also, I only have 16 ohm 4X12 cabs for speakers.
Click to expand...


Champs use a 6V6 power tube. You can find Raytheon and othe NOS '50s and '60s tubes relatively inexpensive. Especially compared to EL34 or 6L6s.

As for speakers, they are spec'd for 4 ohms. The original Tweed Champs only had an 8" speaker. I'm sure they would sound good with something bigger, but still needs to be 4 ohms.

Maybe someone with better understanding of the circuit and transformers used could suggest a way to use a 16 ohm load.

As for what they sound like, Rocky Mountain Way was recorded with a Champ. As well as many other iconic records.
 
I ordered the tubes. I went cheap (JJ's) since this is an experiment and will upgrade later if I don't smoke it. Did an inventory and only needed to order the B+ caps. My shop area is still undergoing renovation so it's a miracle I found anything. :blink:
 
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