5AR4/EL34 to 5Y3/5881... what can I expect?

[bluesbear]

I guess my son is growing up. He's 30 so it's about time. I built him a '59 Bassman/Bluesbreaker that sounds wonderful. He loves it. Problem is, he's realized that it's just too damn loud. It has a 5AR4 rectifier with EL34's with 425v to the plates. If I run a 5Y3 with 5881's, it'll have about 360v to the plates. It'll work fine but will it help much? I'm guessing it's running at about 45 watts now. Would anyone care to guess how many watts this will drop? He's sure 6V6's won't be enough and given the band he's in, he's probably right. If I could get this down to about 30 - 35 watts, it might just do the trick.
Thanks!!
Dave

[Geezer]

I don't like 5Y3's because of the sag/ loss of quick response. I suspect your son has gotten used to the tightness of the amp & will probably be dissappointed at the result, but maybe not(?).....it's an easy swap & pretty quick for him to see how it works for him.

Who knows, he may just love it!

However, I'm not convinced (from experience) that the amp will actually be that much "less loud", although the attack on the notes will be softened somewhat, so it may seem/feel like less watts....never know 'till you try.

Another option could be to try cathode bias....that will definately bring down the watts, but retain most of the "tightness".

Good luck, & congrats on the maturing son!  

[sluckey]

I don't recall ever seeing a 5Y3 paired with PP 5881s. (Don't mean it can't be done)

I think VVR should be considered. Might even be cheaper too.

[bluesbear]

I know exactly what you're saying. I wasn't sure how much the lower voltage would lower the wattage. Cathode bias 5881's is an idea. As far as the 5Y3, I don't really see that much difference with the 5AR4 except you have to turn up louder to get the same effect. He's played my amp (5Y3 and cathode biased 6V6's, otherwise identical to his) and been perfectly happy with it. It's plenty loud enough for my band but maybe not his. Somehow my amps are tight as a drum with 5Y3's. I'm not sure why; maybe it's because I go with BF voltages to the power amp and SF voltages to the PI and pre. I like clean headroom.
I guess the only way to get between the 20 watt 6V6's and the 40+ watt 6L6/el34 levels is 4 EL84's or 4 6V6's. Maybe I'll do a 4 6V6 and see how it works. Any other ideas on how to achieve this would be appreciated.
Thanks,
Dave

[tubenit]

I like the 5V4 rectifiers Hoffman sells with 5881's real well. I think that's a great rectifier tube.

I think there was a Silvertone or Dano amp that had P/P 6L6's with a 5Y3?  But can't remember for sure?

I like the VVR idea.

FWIW, the cathode biased 5881 amps I've done are/were an guesstimated 23 watts measuring across the speaker terminals and dividing etc......

With respect, Tubenit

[Geezer]

Somehow my amps are tight as a drum with 5Y3's. I'm not sure why; maybe it's because I go with BF voltages to the power amp and SF voltages to the PI and pre. I like clean headroom.

I suspect the difference is fixed bias (yours) vs cathode bias (mine). Cathode bias is already a bit more saggy, so the added sag of the 5y3 is more obvious (to my ears).

I think you should pop in the 6l6's/5881's with the 5y3 & see what happens....you don't even have to fire up the soldering iron.

G

[Backwoods Joe]

bluesbear, try a set 6V6's. 425V + 6V6 + big iron = LOUD!  :shocked:

[Willabe]

FWIW,I think their right about trying the VVR (Power Scaling). More volume options/levels to dial in for a given gig/room all on 1 knob. That would've made giging SOOO much easer when I used to play out. You can dial in "your tone" "sweet spot" on the amp, at the volume you need. If I ever go back to playin out, including at church, I will absolutly with out a doubt have it on/in the amp I'm playin through. There were times when I needed a little more volume, but no where near the amount of times I needed less. Nothin worse than the bar owner standin in front of you about 3 songs into the 1'st set tellin you to turn down,      (gonna be a another long night   ) never again! Even if you don't need it every gig, it's nice to have it at the turn of a knob when you do and sooner or later you will. I'll go a step further, I think it's as nessary as having extra strings and a spare guitar cord with you when you play out, you never know when you'll need them.


             Brad               

[DummyLoad]

BB, i don't think EL34 to 5881 is much of downgrade. EL34 to 6V6 w/ 5Y3 might be the path you seek. VVR is an option. never played with it tho, so don't know. have read good and bad reviews on it. i guess it's one of those things you'll have to try then formulate your own opinion.

--ISO

[bluesbear]

"I suspect the difference is fixed bias (yours) vs cathode bias (mine)."

Actually, mine are cathode biased. Still, very tight, nothing like a tweed Deluxe, for instance. The little one is 16" x 16" with a 10" speaker, cathode bias 6V6's. It holds it's own with 45 watt newer Fenders. A friend (poor, sadly) borrows it every Monday for an Allman Bros tribute thing. The other guy uses a Marshall Bluesbreaker. Mine doesn't even sweat. Don't ask me why. In my old band, it was weird to be asked to turn down when the other guys Blues Deluxe was on 7 and my baby amp was on 4.
Still, my son's bunch is mostly in their 20's. I'm not certain 15 - 20 watts will cut it. I think a 5Y3 and fixed bias 5881's is probably the best place to start... just because it's easy. Then on to cathode biasing if needed. The real answer would probably be a 4 6V6 amp but that can't happen for a while though it is on the future project list.
Thanks all!
Dave

[Tone Junkie]

Bluesbear  you need to try the vvr or the ppimv master volume on other forums they call it a lar/mar mv but it really came from the train wreck pages if I understand correctly.
 non the less in my marshall or fender or what ever I make now I use that master volume. I will be trying the vvr in my next amp, but I can dial in the sound i want and be able to turn it to 4 or 5 depending on the amp and get the same sound as if it were on 10 thats important to have sound wise for me anyway.
 I know the young guys are usually louder when they play but thats only because there drummers dont know how to play quiet yet. (LOL)

[stingray_65]

what about a fixed/cathode bias switch?

just a thought

Ray

[bluesbear]

I wish I could actually fiddle with a VVR. There are a bunch of You Tube demos but they all sound like crap to me. If it sounds as muddled as those clips (best description I can think of), I'd rather build another amp. My son gets better tones out of his Line 6. Of course, I don't know these people. I'd bet they play with what I call lousy tone even without the VVR. I know a lot of you swear by them and I really do trust your judgements... but I sure wish I could play through one myself! I suppose I should try one on my larger cathode bias amp. Only $30 + $2 to try and If I like it, we can try it on his. I've never messed with any SS circuits. That makes me a bit nervous!
Thanks again,
Dave

[rzenc]

Just a reminder BluesBlear, How much capacitance is in the first filtering stage? 47uF?? I believe you should check it in order not to exceed max input capacitance with 5Y3 - as far as I understand it, it's related to how much current you are demanding from your tube recto.

Hope this helps,
Best Regards.

Rzenc

[bluesbear]

"How much capacitance is in the first filtering stage?"

No sweat there, I use standard 5F6a filtering: 40-20-20-20.

Thanks,
Dave

[rzenc]

Check the following capacitor input chart I found from GE 5Y3GT. I did not build a 5F6A yet , but I have a plexi + hotswitch running with 6L6GC and it drags around 70mA per bottle at full roar- biased @ 45mA per bottle in quiescent. I followed instructions on the upper right hand corner from the chart bellow and got 0.94 efficiency - plugged in voltages found @ fender bassman 5F6a schematic.It points out for 25mA....I believe these spec charts are rather conservative, so am I  .
Maybe someone with deeper knowledge around power supply desings can point out whether it might give you headaches...
For instance, I found TWIN 5D8 schematic showing 2x 5Y3 connected in parallel working with 2x16uF @ first filter node - giving 32uF total input capacitance.

Hope this helps.
Best Regards,

Rzenc

[67polara]

Looks like the 5y3 has a voltage drop of 60 volts at 125ma.  What do you expect the total draw will be? 

Tony

[dude]

bluesbear, try the VVR running full voltage to the preamp and power scaled the output.

For $50 you can get Dana's small fixed biased pcb bd that fits right on a volume pot, you can go cathode biased for $30.

Like others have mentioned here, I swear by these little bds and have never had any tone issues as long as I didn't try to turn down to bedroom levels.

I use a small PC 12v fan and processor heat sink for an added safety measure in amps over 20 watts. I run it off the 5v tap and you can't hear the fan, I've also ran them rectified off the heater supply. I think the draw is very minimal off the PT.

Your son will have the best of all worlds.

al 

[bluesbear]

"try the VVR running full voltage to the preamp and power scaled the output."

Is this just a matter of separating the B+ or is there more involved... or do the instructions that come with it cover this? It seems likely to me that the examples I've heard probably bring down the preamp, also. That might explain the mud I've heard. This seems like it could work.
Thanks,
Dave

[Geezer]

Here's some reading/info>>

http://www.el34world.com/Forum/index.php?topic=6899.0

Be sure to look at all the examples.

You want to separate the preamp from the poweramp (PI & output tubes) just scaling the poweramp & keeping the same voltage (tone) from the preamp (at least that's been my best experience with the VVR).

G

[Willabe]

is this just a matter of separating the B+

Yes, tubenit and/or Geezer have examples in some off their amps in the SCH files section. IIRC one or more of the TOS, COS, and Tweed BluezMeister. There's also a PP 6AQ5 amp in there that has it too. Just make a -Y- in/off the main B+, using two diode's. One diode feeds the VVR (Power Scaling), the other feeds the preamp. IIRC the diode feeds the VVR pulsating DC, making it easer on the Mosfet, and the other diode helps to block/stop the preamp B+ from droping when using the VVR. You can do just the plate and screen of the PP pair or, and this would be my preferance, also do the PI. That helps bring down the drive to the PP pair automatically, when turning down the B+, this keeps the tone the same longer through the rotation. If you want to go even lower with the volume, while keeping the same tone, you have to add either a PPIMV or a boot straped PIMV. When you have less B+ on the OP tubes, it takes less voltage to drive them, so to keep the same tone at lower volume, longer through the rotation you have to be able to adjust the drive. Doing this and separating the preamp off of the VVR B+ will help greatly. Some guys miss this (and/or VVR the whole amp) and then say it does'nt work without changing the tone or you can only turn it down a little before the tone changes. Depends on how you do it. I don't know if Dana's will take on a full 40/45w amp, I thought his were good to only 30ish watts, but I could be wrong. All you have to do to up grade, is get higher rated mosfet.

Hope this helps you and your son.


             Brad             
                           

[dude]

"try the VVR running full voltage to the preamp and power scaled the output."

Is this just a matter of separating the B+ or is there more involved... or do the instructions that come with it cover this? It seems likely to me that the examples I've heard probably bring down the preamp, also. That might explain the mud I've heard. This seems like it could work.
Thanks,
Dave

Yes, instructions all included.

http://www.hallamplification.com/main.html?src=%2F#2,2

A simple hook-up between the standby switch and the first filter, you use diodes to keep your voltages to the preamp from dropping as you turn down the B+. So you can dial in any B+ you want. I did find that when you get under 200vdc on the B+ you lose highs and the tone suffers, maybe that's what you heard on You-tube...?  But who turns down that low..?   The fixed biased version also changes the bias as you turn down so once you bias the tubes you're done.

I use the VVR about 1/4 the way down and adjust the gain and volume for the best tone, I find every venue is different so no one setting for all.

I would get the fixed biased (just opinion though) a little more hook-up involved but Dana's instructions are great. Just do the power tubes and not the pre-amp voltages. You wouldn't have to fool with changing to cathode bias either.

You can talk to Dana through emails, he's great. I believe the Hall brothers actually invented the VVR but not positive.

Just my opinion, I would use a small PC processor dc fan and heat sink on the opposite side of the chassis where the mosfet is screwed down. This just gives some added protection for the heat generated especially on amps over 25 watts. But they say you don't need it...?

al  

[Willabe]

Hi, dude

I was wondering, did you VVR only the output tubes, or did you also VVR the PI too?


         Thanks,    Brad         

[bluesbear]

Yes, the schematics indicate that the PI was included. Seems to me that would make it harder to get clean headroom, at least in the same manner as before. I'd like to know about that. I emailed Hall and they're sending me the instructions later. They're supposed to address leaving out the preamp. I won't know how they handle the PI till I see them.
Dave

[punkykatt]

Bluesbear. try running the power tubes in triode. or put in a pentode triode switch. Punky

[Willabe]

Yeah, tubenit and Geezer did, but I was wondering if dude did since he mentioned treble roll off after a certain amount of VVR being applied.

Some guys do and some don't by choice, some like it better with, some without PI VVR'ed, but it will respond differently at different points of rotation. Treble roll off and distortion being key points of difference. One is not necessarily better, I guess it's what gets the job done for how much volume reduction you need and if you like the sound at that amount of volume. 

The guys who've taken it all the way down to almost a wisper, with no change of tone (their words) that I've read including KoC say PI and one of the two MV's mentioned earlier are a must.

There is also some debate about how Dana "tracks" the bias voltage using a dual ganged pot instead of how KoC implements the bias tracking, which (Dana's) is said by some not keep the OP tube transfer curve intact/constant as the VVR (Power Scaling) control is rotated. Which will change the tone/sound.

Now I will be the 1'st to say most of this is over my head, I bring these points up for more to work with and not to say I know whats best.

I hope this is helpfull.


           Brad           
       

[dude]

Hi, dude

I was wondering, did you VVR only the output tubes, or did you also VVR the PI too?


         Thanks,    Brad        

 This is the schematic I used:  I used both diodes

[bluesbear]

Well. I think I've gotten about all the info I can specific to the amp. I need more info about the VVR but I'll start a new topic since it's more generic... I'm going to try it on a couple of amps, a cathode bias and my son's fixed.
Thanks!!
Dave

[tomcatarnold]

  5U4G recto and I would stay with EL34s or 5881's..  and if you don't already, get 2 or 3 1" VC 15-20 watt alnico speakers mixed in with the existing speakers.  Weber Signature Series 10S alnico's would be the best cost/quality option..  Jensen RI P10R..  Weber 10A100..   The inefficient speakers will tame the amp down a lot without having to make any changes to the circuit.  Also, I would be afraid to hit a 5y3 recto with a 5f6a PT.  Dropping that much voltage, it's gonna run hot hot HOT.