Dual Showman head setup for steel

Brian Stear · Post by **Brian Stear** » 3 May 2001 6:56 am

This is a 1968 Dual Showman ( no reverb ) setup with 2 GE 6550A's at 8 Ohms. It's the AB763 circuit.Has a blackface faceplate and grillecloth from Rodgers reproductions. Cabinet is a little beat up, but all there. Tolex is fair to good, depending on your personal opinion..........
Great bottom end response with those tubes. You lose a few watts, but gain beaucoup headroom and tone.
You get the looks and tone of a blackface amp at much less.
This was Cartwright Thompson's amp.
$375 + shipping

Len Amaral · Post by **Len Amaral** » 3 May 2001 7:39 am

Hi Brian:
I'll take the amp! Check your email.
Thanks,
Len Amaral

Cartwright Thompson · Post by **Cartwright Thompson** » 4 May 2001 6:17 am

Good move Len, that is a great amp. If I didn't have an old twin set-up the same way(6550's and a D-130) I never would have sold it to Brian.

Brian Stear · Post by **Brian Stear** » 4 May 2001 6:55 am

Cartwright's right on this one. It's a great amp for steel. Good for guitar also! Those 6550's are DEFINETLY a great tube to put in an old Fender.
Some of the other guys on the Forum ought to try this. You have to change the screen resistors I believe and bias accordingly. Plus using two tubes sets up the impedance to work at 8 Ohms, which is nice also. You'll will be suprised for sure.....[This message was edited by Brian Stear on 04 May 2001 at 07:56 AM.]

Len Amaral · Post by **Len Amaral** » 4 May 2001 7:44 am

Thanks Brian & Cartwright! I have several speaker setups I can use with this amp. You mentionbed that the amp is set up for 8 ohms. If i use two 8 ohm speakers, this will drop the amp load to 4 ohms. I assume this is OK as all Fender amps have an extension speaker jack to add another speaker? BTW! I have a pair of JBL-D130 speakers, a single 4ohm JBL-E130 - 4ohm and a single JBL-E130 - 8 ohm speaker. I also have a pair of EV-12L 8 ohm speakers so it will be interesting to see what responds with the amp.
Regards,
Lenny [This message was edited by Len Amaral on 04 May 2001 at 08:48 AM.]

Rich Gibson · Post by **Rich Gibson** » 4 May 2001 12:36 pm

Do you guys know the exact specs to make this mod?I'd like to try it.
Thanks
Rich Gibson

Cartwright Thompson · Post by **Cartwright Thompson** » 5 May 2001 1:47 am

Len,
You might also try hooking up 2-8ohm speakers in series for a 16ohm load, a little less power but it might "tighten-up" the bass and be a little easier on the amp.
Rich,
Change the screen resistors to 1K,5Watt (wire-wound,"sandbox" ) and re-bias.
This is for 4 - 6L6 amps,twins and dual showmans, where you're using 2- 6550's (in the inside two sockets)instead. "Single" Showmans have 8 ohm output transformers, if you do this mod with those models you will effectively change the output impedance to 16 ohms.

Jerry Erickson · Post by **Jerry Erickson** » 5 May 2001 10:33 am

Hey Rich,
You might look in Gerald Weber's Desktop reference book.It's got the info in a chapter on making a tube amp work better for steel guitar.
Good Luck

Rich Gibson · Post by **Rich Gibson** » 5 May 2001 11:56 am

Thanks Cartwright.I'm going to try it.There's alot of non-master silver faces out there that even if they need a cap job are a bargin.
Thanks Jerry.I hear that's a good book.
Rich