Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ernie_jr on August 31, 2012, 07:19:15 am
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Can I use an output tranny with 3.3k load for a PP 6L6's, or would 6.6K work better?
Thanks,
Ernie
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I think I would use the latter, maybe?. The 3.3 will work well for EL34's. What OT is it? I have tried numerous for 6l6's and found 5.5 to 5.9 to be best, however, I do have an amp using 6.6 for 6l6. Sort of a blackface deluxe AB763. It will run 6v6 and 6l6. Prefers 6v6.
My 2¢
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You can use either.
Which is best depends on your supply voltage, desired power output and desired distortion characteristics (but mostly the supply voltage and power output desired).
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Plate voltage is around 440 and was looking for around 35- 40 watts as this will be be an Ampeg bassed practice amp.
Thanks,
Ernie
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Can I use an output tranny with 3.3k load for a PP 6L6's, or would 6.6K work better?
Thanks,
Ernie
For asking wich primary impedance ( load ) you need, you must say before wich output (speaker load ) you want)
3.3 k will work "better" with 4 ohms load . 8 ohms need higher primary impedance ( load )
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Plate voltage is around 440 and was looking for around 35- 40 watts as this will be be an Ampeg bassed practice amp.
Thanks,
Ernie
just to give you a starting reference: fender used 4k for 2 x 6L6GC in the 5F6A; marshall used 6.6K or 8K (depending on the year made) in the JTM45.
try both, then decide?
--DL
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Plate voltage is around 440 and was looking for around 35- 40 watts as this will be be an Ampeg bassed practice amp.
Thanks,
Ernie
just to give you a starting reference: fender used 4k for 2 x 6L6GC in the 5F6A; marshall used 6.6K or 8K (depending on the year made) in the JTM45.
try both, then decide?
--DL
For the same speaker load ?
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> 3.3 k will work "better" with 4 ohms load . 8 ohms need higher primary impedance ( load )
I don't understand.
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OK, I'm going to throw a spanner into the works here. I bought a OT and when delivered discovered that it only had a single tap of 2ohms :BangHead: I was wanting to use IT in my next build.It specs are 4k into 2ohms and as i believe it,this would be 8k into 4ohms,correct?? would this be too high for a pair of JJ 6L6s with a plate voltage of about 400v. :dontknow:
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OK, I'm going to throw a spanner into the works here. I bought a OT and when delivered discovered that it only had a single tap of 2ohms :BangHead: I was wanting to use IT in my next build.It specs are 4k into 2ohms and as i believe it,this would be 8k into 4ohms,correct?? would this be too high for a pair of JJ 6L6s with a plate voltage of about 400v. :dontknow:
Fender use often 4 k for 4 ohms speaker load ; Pro-Reverb, Tremolux, Vibrolux. These amps use pair of 6L6.
Is this output transformer have enough power ?
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OK, I'm going to throw a spanner into the works here. I bought a OT and when delivered discovered that it only had a single tap of 2ohms :BangHead: I was wanting to use IT in my next build.It specs are 4k into 2ohms and as i believe it,this would be 8k into 4ohms,correct?? would this be too high for a pair of JJ 6L6s with a plate voltage of about 400v. :dontknow:
Fender use often 4 k for 4 ohms speaker load ; Pro-Reverb, Tremolux, Vibrolux. These amps use pair of 6L6.
Is this output transformer have enough power ?
if TIMBO HAS a transformer that is specified to have 4K ohms on the primary with 2 ohms load on the secondary then the REFLECTED impedance is 4K ohms on the primary. if TIMBO DOUBLES the load on the secondary from 2 ohms to 4 ohms then the REFLECTED load of the primary is DOUBLED from 4K to 8K. understand? TIMBO wants to use 4 ohms load with his transformer and is ask will 8K work. yes it will. it is not optimal, but it will work.
--DL
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Thanks DL, Good explaination, OK, so an OT may not be matched perfectly to a pair of tubes but is there a UP/DOWNSIDE when doing this? I have another OT (hammond 1650F) which i am lead to believe is better suited for 6L6s/6V6s but when compaired in size (the OT is a hammond 1750K) the 1650F is a lot smaller.What i am trying to get at is would size help when you miss match OTs to tubes.As i see it if you are increasing the load would a bigger OT make for a better sound?
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You can use the 2 ohm 1750k OT all day long with a 4 ohm speaker load.No problems at all.
The 1650F is a 25 watt OT so it would be a bit undersized for a pair of 6L6's in fixed bias but happy with cathode biased 6L6's at about 390v or so on the plates.
The bassman OT would be fatter sounding but the 1650F might be like using a vibrolux OT in a Super.Crunchy.
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if TIMBO HAS a transformer that is specified to have 4K ohms on the primary with 2 ohms load on the secondary then the REFLECTED impedance is 4K ohms on the primary. if TIMBO DOUBLES the load on the secondary from 2 ohms to 4 ohms then the REFLECTED load of the primary is DOUBLED from 4K to 8K. understand? TIMBO wants to use 4 ohms load with his transformer and is ask will 8K work. yes it will. it is not optimal, but it will work.
--DL
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You are absolutly right Dummyload , I answer to early in the morning ...before my coffe.
Sorry
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I have another OT (hammond 1650F) which i am lead to believe is better suited for 6L6s/6V6s
That's what I chose to use in some EL84 amps. 7600Ω:4/8/16Ω
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1650F
suited best with lower power output. 2 x 6L6GC AB1 fixed bias will likely stress the primary winding and exhibit excessive core saturation. use 1650F OT with a pair of 6L6GB cathode biased, 6V6, 6CM5, EL84 or a single 6DZ7...
a nice pair 6DZ7 here... (http://www.ebay.com/itm/1960s-NOS-NIB-Pair-RCA-6DZ7-Power-Tubes-Dual-EL84-6BQ5-/150873454652?pt=Vintage_Electronics_R2&hash=item2320c2383c#ht_1623wt_1396)
cool tube - a pair of 7189As in a single octal envelope.
--DL
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Sorry ernie jr if i hijacked your topic. I'm like you i have to run these things by the wise ones before i jump into anything and your topic was close to the info i needed. When a lot of these specs are given they are said to be OPTIMAL but i do believe that there is a FUDGE factor that can be to our advantage but knowing how much FUDGE you can apply i think comes years of tweaking and knowledge that this forum has plenty of. I like when i can stray from the NORM because this gives my amp its unique sound. :icon_biggrin:
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No problem,
more stuff for us all to learn.
Ernie