6V6's in a #183, what would I need to change?

[markmalin]

Hey guys,

I'm sure this topic has been asked before, so please feel free to forward me to a discussion

I'm building a 50W version of #183 using schematics I've found on line. I know with the D'Lite amps, for example, I used to interchange 6L6's and 6V6's and just adjust the impedance selector to match the reflected impedance of the tubes I was using. If I remember correctly, for an 8 Ohm speaker with 6L6's I used the 8 ohm tap, but with 6V6's I'd use the 4 Ohm tap and re-bias.

I need to better understand this, so feel free to lecture. On the #183 pin 1 and 8 are tied to a bias test point, then to ground via a 1 ohm resistor. Anyhow, if I swapped in 6V6's and changed the impedance switch appropriately, would I be good to go? For reference, here's a copy of a schem from Ceriatone for their OTS "183":

Humbly,
Mark.

[ToneMerc]

Mark, I have built a few quad 6V6 ODS amp using 50W (3.4-3.8K, 4-8-16)Marshall output transformers. So if you are running a quad of 6V6's and your typical 50W( 3.4-4.4K) OT, you dont really have to make a impedance load change, unless you want to run a mismatch. The only real changes I made was in the bias supply; the bias resistor to 750-820R and tail resistor to 11K-16K. I tend to setup the bias supply so that it can run a pair of 6L6, EL34 or a quad of 6V6's.

FWIW, I used custom PT's so I could only hit the plates at 390-410V and run tubes other than JJ's. If you going to have the high plate voltages, you may want to stick with JJ's.

TM

[ToneMerc]

Here's a quad 6V6; mid/low plates, skyliner eq, 250K(OD controls) and Marshall 50W OT.Also, notice filtering is only 50uF.

TM

[markmalin]

Thanks for the info, I appreciate it.

Sorry for the confusion - what I'm trying to figure out is, with my 50W 6L6 pair version of 183, can I simply swap in a pair of 6V6's (assuming JJ's for the added voltage handling capabilities) and just change the impedance selector (and re-bias it). Or if there is any other modification I need to make. The OT is a Hammond which I normally use for 6L6's and EL34's. I'll have to look at the model, I forget off hand.

[ToneMerc]

Thanks for the info, I appreciate it.

Sorry for the confusion - what I'm trying to figure out is, with my 50W 6L6 pair version of 183, can I simply swap in a pair of 6V6's (assuming JJ's for the added voltage handling capabilities) and just change the impedance selector (and re-bias it). Or if there is any other modification I need to make. The OT is a Hammond which I normally use for 6L6's and EL34's. I'll have to look at the model, I forget off hand.

Ok so you are actually building a 50W version of "183" and for grins you want to run a pair of 6V6's at 25W. Then yes, assuming your 50W OT is let's a say 4K: 4-8-16, then using a a pair of 6V6's it would be 8K:8-16-32. Thus, install the 6V6's and run an 8 ohm cab off the normal 4 ohm tap.

FWIW, the D'Lite 22/44W amps used a multitapped primary OT, which kept the same 4-8-16 relationship with either output tube type.

As far as "other modification"; you may need to modify your particular bias supply circuit values to bias 6V6's between 17-22mA.

TM

[markmalin]

Thanks, ToneMerc. I truly appreciate the help. Again, sorry for the initial confusion. This makes sense - I'll have to see if my bias circuit can get the 6V6's down to 17-22ma and adjust the bias supply parts as necessary.

Thanks again!
Mark.

Thanks for the info, I appreciate it.

Sorry for the confusion - what I'm trying to figure out is, with my 50W 6L6 pair version of 183, can I simply swap in a pair of 6V6's (assuming JJ's for the added voltage handling capabilities) and just change the impedance selector (and re-bias it). Or if there is any other modification I need to make. The OT is a Hammond which I normally use for 6L6's and EL34's. I'll have to look at the model, I forget off hand.

Ok so you are actually building a 50W version of "183" and for grins you want to run a pair of 6V6's at 25W. Then yes, assuming your 50W OT is let's a say 4K: 4-8-16, then using a a pair of 6V6's it would be 8K:8-16-32. Thus, install the 6V6's and run an 8 ohm cab off the normal 4 ohm tap.

FWIW, the D'Lite 22/44W amps used a multitapped primary OT, which kept the same 4-8-16 relationship with either output tube type.

As far as "other modification"; you may need to modify your particular bias supply circuit values to bias 6V6's between 17-22mA.

TM

[ToneMerc]

Thanks, ToneMerc. I truly appreciate the help. Again, sorry for the initial confusion. This makes sense - I'll have to see if my bias circuit can get the 6V6's down to 17-22ma and adjust the bias supply parts as necessary.

Thanks again!
Mark.

Thanks for the info, I appreciate it.

Sorry for the confusion - what I'm trying to figure out is, with my 50W 6L6 pair version of 183, can I simply swap in a pair of 6V6's (assuming JJ's for the added voltage handling capabilities) and just change the impedance selector (and re-bias it). Or if there is any other modification I need to make. The OT is a Hammond which I normally use for 6L6's and EL34's. I'll have to look at the model, I forget off hand.

Ok so you are actually building a 50W version of "183" and for grins you want to run a pair of 6V6's at 25W. Then yes, assuming your 50W OT is let's a say 4K: 4-8-16, then using a a pair of 6V6's it would be 8K:8-16-32. Thus, install the 6V6's and run an 8 ohm cab off the normal 4 ohm tap.

FWIW, the D'Lite 22/44W amps used a multitapped primary OT, which kept the same 4-8-16 relationship with either output tube type.

As far as "other modification"; you may need to modify your particular bias supply circuit values to bias 6V6's between 17-22mA.

TM

No worries, you're welcome.

TM

[talbany]

The other possible issue I see with this is 183 has both 250k drive and level controls on the OD side causing the OD to have considerably more bass response than the Dlight circuit (2X100k's),which those 6V's could get a little flabby and congested
Remember that preamp is designed/voiced for a 100w output section.

Tony

[amplifiednation]

Here's a quad 6V6; mid/low plates, skyliner eq, 250K(OD controls) and Marshall 50W OT.Also, notice filtering is only 50uF.

TM

Mike are those small blue metal films Xicon or NTE? Or something else?

Also does the ceramic cap on the standby switch help to eliminate popping? I see you have one on the IEC as well. I know they are used to help with arcing...

The build looks great

[ToneMerc]

Here's a quad 6V6; mid/low plates, skyliner eq, 250K(OD controls) and Marshall 50W OT.Also, notice filtering is only 50uF.

TM

Mike are those small blue metal films Xicon or NTE? Or something else?

Also does the ceramic cap on the standby switch help to eliminate popping? I see you have one on the IEC as well. I know they are used to help with arcing...

The build looks great

Taylor, those small blue mf's are Speer. Yes, a .01 1KV cap on the standby and a 150V MOV across the IEC. I have since gotten away from an MOV across the mains. You have seen this one before, this was a 2011 build using one of your cabs.

thanks

TM

[markmalin]

The other possible issue I see with this is 183 has both 250k drive and level controls on the OD side causing the OD to have considerably more bass response than the Dlight circuit (2X100k's),which those 6V's could get a little flabby and congested
Remember that preamp is designed/voiced for a 100w output section.

Tony

Tony
Thanks for the input. I remember the D'Lite I built used 100k pots - now I know why. Good info!
Mark