Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tone Junkie on May 30, 2012, 02:15:24 pm

Title: Most power with 450DC volts 6550 or kt 88
Post by: Tone Junkie on May 30, 2012, 02:15:24 pm

Title says it all im looking for most clean power from either of these tubes Ive never built an amp with either so need info.Any ideas on best new production tube in either would als be helpfull.
Thanks Bill

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: PRR on May 30, 2012, 08:47:42 pm

No difference 6550 or KT88. They are nearly the same tube originally. Current production probably is the same guts in different bottles.

At the 450V level 6L6GC or EL34 give as much power as the hi-price bottles.

"MOST Power" at 450V might be TV H-sweep tubes working with odd (low) impedance load. That sounds like more trouble than it is worth.

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: Willabe on May 31, 2012, 01:58:17 am

Hi Tone Junkie,

I think the problem is _if_ your trying to get _max power_ just by changing the power tubes still with a 450v B+ that won't happen. You will/might get more head room/cleaner sound by using a bigger power tube, but that still won't give you more output power.

Look at tube spec sheets for 6550/KT88 B+ output and you'll see you need a higher B+ power supply rail to get _max power_ that those tubes will allow.

Why do you want/need so much power?


                         Brad      :icon_biggrin:  

  

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: Tone Junkie on May 31, 2012, 02:06:07 am

Just playing around with differant things Ive never tried those tubes before.
I will go with PRR,s thoughts might as well stick with the 6ca7,s I have.
Thanks Bill

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: Willabe on May 31, 2012, 02:21:45 am

Reading back I see "Most Power", than "most clean power". This can be 2 different things.

I would think that true 6CA7's, (either American made or new Euro made) and are beam pentode as opposed to Euro made EL34's, true pentodes, will give you a cleaner sound/more head room than 6L6's.

Now that's if you have the PT heater current to use them.



                                Brad        :icon_biggrin:  

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: Ritchie200 on June 02, 2012, 01:01:02 am

Hey TJ,

Have you thought about a UL circuit?  Something along the lines of a Major, but with good iron?  Lots of thump and clean headroom.  My personal preference is the =C= KT88.  Much smoother than any 6550 and is true to the old KT88 design, unlike the majority of other KT88's on the market (as PRR said).  The big Hammond OPTX have the UL taps.  You can run a quad of these guys at those voltages and not break a sweat for about 150 watts.  6L6? Yuck! :laugh:

Jim

Title: Re: Most power with 450DC volts 6550 or kt 88
Post by: Tone Junkie on June 04, 2012, 12:04:48 am

I do have the the quad of 6ca7,s and the power to run them, my thinking was if I could get the same amount of power from 2 kt88 then it would leave me more room to do other things.
But I already have the iron, and would have to do something differant.
 I will just stick with the original plan.
 Thanks guys