D'Mars ODS EL84 amp

[tubenit]

One of the forum members is starting a build of a D'Mars ODS (quad)  EL84 amp.

Knowing the D'Mars ODS original and that EL84's break up sooner ....................... I have made these suggestions.  

Since I am not too keen on EL84 amps,  I wanted to post this here to give others who have more of a love of EL84's to have a chance to help this forum member with tweak ideas.   PLEASE toss some other ideas out that you think might be useful to him.   I'd love to see this project be a great success for him.  And I really like seeing forum guys here doing innovative stuff. I think this forum has an abundance of creativity.



EL84's break up MUCH easier than 5881's.

In light of that,  I have listed some suggestions.  

1)  First thing I'd do is change everything that I am showing from the LTPI thru power tubes.  Especially the coupling cap into the LTPI
     needs to be .01 or even .0047.  The coupling caps after the LTPI prior to the power tubes should probably be lowered to .01 or .02?

2)  IF you are still getting too much gain in the OD mode, then I'd change the OD values that I am showing.

3)  IF you are still getting too much gain in the clean mode,  first thing I'd do is change the coupling cap into the FX loop

4)  IF after all that,  you're still getting too much gain change the volume pot from 500k to 250k and the slope resistor to 68k

I will be watching this build with great interest.  I hope you'll post ongoing pics and info on the Tweaks section.  I am going to get a thread called D'Mars ODS EL84 started and you can have that be your thread and add to it.    This would be a great project to get additional info from Geezer and others on the forum so you'll be pleased with the result.

With respect, Tubenit

[Glennjeff]

Need to figure out where to put another bottle .

[Glennjeff]

tubenit,

Whilst I have complete faith that what you are saying is factual and practical advice my heart was set on that pentode OD. I will be building a 5881 version with my second chassis after this project and wanted to use this project to "get into the swing" of amp design / construction. Seems I may have jumped into the deep end of the pool.

I'm wondering if it would be possible to put the LTPI valve behind the EL84's in between the PT and OT somewhere? Would there be issues with interference from the transformers? Would the extra cable run to the LTPI through that part of the circuitry be problematic for lead dress and parasitic oscillations? Will I have enough physical space given the length of the PTP board?

Here I may be completely off base so forgive if the following is nonsensical.

A subsection of the modifications you are suggesting generally amount to reducing coupling capacitors, so I am wondering if the purpose of that it to roll off the bass response somewhat thereby reducing the possibility of overdriving the power amp section / valves.

If the active FX loop is included, will dialling down the FX return gain somewhat compensate for the over voltage coming from the preamp. I've just realised that "thinking like a guitar amp developer" is a completely different game to "thinking like a mixing desk technician". Doh.

Thanks for your efforts and I will ponder your suggestions further. Nothing is set in stone for this project.

All the best.

[Glennjeff]

Perhaps another 9 pin could be placed between first and second preamp tubes, set back so as to form an equilateral triangle. Could this create overheating or parasitics? Might I get away with it? Is it worth a try?

[tubenit]

Perhaps another 9 pin could be placed between first and second preamp tubes, set back so as to form an equilateral triangle. Could this create overheating or parasitics? Might I get away with it? Is it worth a try?

I've done that successfully on several amps without oscillation.

Another option (that you may or may not want to consider) is just have the 5879 be the OD section.  It works and sounds very good to my ears.  I did that on the Tweed OD Lite (which I built for me son)

No agenda for you at all ................ just creating options to consider.

With EL84 tubes, my perception is that IF the mids are accented too much that you'll lose the smoothness needed in the overdrive. So, the suggested cap value changes are to reduce the range that adds too much grit. The suggestions are based on lots of experimenting on my amps.

The FX send and level pots reduce gain from preamp and function well as a master volume.  You might want to skip the PPIMV, ........... but with EL84 tubes being so easily overdriven, I think the PPIMV would be worth having.

With respect, Tubenit

[Glennjeff]

Thanks tubenit.

Put a signal generator between live and neutral, 2.5 V  50Hz make sure the AC voltages are in order and then -  the scary bit.
 

[Willabe]

The red and the blue wires sniped short on the PT primary need to be capped off with some heat shrink for safety.

Depending on what/where the red and yellow wires wrapped around the green wire come from/are hooked up to they need to be taped or caped off before applying voltage for testing, again for safety.



                    Brad         

[Glennjeff]

Willabe,

Absolutely correct.
The yellow wire is B+ unfiltered.
My bad for posting the photo prematurely.
 Thanks

The glow of heaters is like a warm open log fire.
405 V DC unloaded into 50uF.

Now to discharge the capacitor with an appropriate resistor before packing up for the night.

[Glennjeff]

Many thanks tubenit, that will save a lot of thinking. I can't get JSchem to display the grid, could you tell me the basic unit of spacing between turret columns.

I will go with the full 3 bottle preamp and put in the extra valve. Dog with a bone.

Discovered on the net that EL84 has maximum recommended plate/cathode voltage of 300V yet most common guitar amp circuits run 325 V or more (385 even ). HiFi guys seem amazed that these valves cope OK with this thrashing.

Could that be why they overdrive so readily. May lowering the DC rail a bit be worth a trial. How could that be done given I have already committed to a power transformer - a different tube rectifier with same pin outs or changing the resistor layout of the supply filter and start at Point B on the power supply.

This was meant to be a lower power option "small home studio"  amp with the ability to switch out 2 of the EL84's, so lost wattage is not an issue.

I'm now waiting for the parts from Hoffman so time to ponder a little.

[tubenit]

could you tell me the basic unit of spacing between turret columns.

Don't remember?  But it's listed somewhere by Doug either on board building info in his sales catalog or in his board building program info.
It's out there somewhere?

OK, looks like you can print off a "template" here and measure the spacing:

http://www.el34world.com/Forum/index.php?topic=12317.0

Do you have a Mac ?  Is that why you're using J-schem?   If you have a PC,  use ExpressSCH.

What are the specs on your PT, please???    A VVR is always one option of lowering plate voltages while keeping preamp voltages up.

With respect, Tubenit

[Glennjeff]

Pri 240 - (-120 - 100 ) - 0
Sec 290 - 0 -290
Tube Rect winding 0 & 5V
heater  3.15 - 0 - 3.15

Its specified for 36 W amp but no idea about current ratings and the iron specs.

The general impression I got from pouring over this forum a couple of months ago was that both VVR's and PPMIV's did a "not real special" job of acting as master volume controls that maintain tonality so they were initially discounted. The VVR however might be perfect for this application. I have located the relevant thread here http://www.el34world.com/Forum/index.php?topic=6899.0

EXPESS SCH and PCB now installed on PC. It looks like main column spacing division is 3/8 inch or 8mm, need to plan how to fit everything into the chassis, may have to mount relay boards vertically close to front pots to get space for the extra valve.

Thanks again, All The Best.

[tubenit]

290 X 1.1 (5Y3GT) = 319v

290 x 1.2 (5V4/5U4GT) = 348v

290 x 1.3 (GZ34) = 377v

290 x 1.4 (solid state) = 406v

I think you can get by using a 5V4 or 5U4GT for a quad of EL84's?  

Besides a VVR in a "set and forget" mode (like on the back of the chassis), & you have other reasonable options for lowering plate voltage if needed.

I am not sure that spacing is correct?  

One option you have with your board is to buy Doug's D'Mars board and use his as a template ........OR buy his board, saw it where the FX would go in & use more board material to create a Hoffman style layout board insert for the FX.

I think the VVR and the PPIMV do a good job as a master volume if you have the pots dialed to "7" or higher.  I don't care for either of them if they are dialed down below "5".

With respect, Tubenit

[Glennjeff]

Think I'll keep the options open. I've already ordered some heavy duty mosfets, so 5V4/5U4GT should be there so we can "plug n play".

You and board members have done a lot of development of the preamp at specific rail voltages and that should not be compromised.

Am making my own board and will probably cut and paste as the build proceeds in sections - Power supply filters, PA/LTPI, Clean pre, OD pre - 4 smaller boards. Will be mindful of integrating the design with Hoffman boards so that it is readily available should it prove successful, which I think it will.

You're a regular goldmine of information by the way.

[tubenit]

OK,   I have edited the SCH schematic and layout to only reflect changes to the LTPI.

And I am including a GIF schematic to show other changes to make IF needed to smooth out the clean and OD.

I erased the other schematics and layouts on the thread to avoid further confusion.

CHECK for ERRORS!   Any inconsistencies between layout and schematic .......... go with schematic.

With respect, Tubenit

[tubenit]

Yet another thought that might be worth considering ........................

What about the idea of a pair of EL84's with their own 130R cathode cap

AND .................

a pair of 6v6's  with their own 330R cathode cap. 

You could pull the EL84's or the 6V6's or combine them ..................

AND with the 330R cathode cap for the 6V6's, you should be able to plug in 5881's without rebiasing.

That would make for a very very versatile amp, IMO.

Just another idea.    with respect, Tubenit

[Glennjeff]

That suggestion of using two different valves in the output stage sounds really interesting.

I wont be doing it with this amp, but have another chassis with 4 big octal sockets where that could be thought about.

I noticed on one commercial amp site that has a quadEL84 design that they don't switch out 1 pair of valves but somehow FADE one pair out claiming to thereby combine "hard driven output tube sounds" with "clean output tube sound".

Some sort of infinitely variable POT to fade across say EL84 and 6V6 pairs (OR 6V6 and 5881) (OR EL84's and 5881) might be cool. That is way outside of my understanding at this point, but if you want to schem some ideas I could start trying to get my head around it. I guess using valves with very different but great sounds would give the most flexibility.

Valves would have to be chosen that require similar OT primary impedance I should imagine.

[tubenit]

A couple of things I would work at being mindful of with your amp building.  Some of this I think may be even more critical using EL84's which at times can sound somewhat harsh/chimey.

1)  I definitely would do the cap foil orientation.  Just takes a few minutes and makes a significant difference in a  quiet amp from what I
     can tell.  This takes me maybe 10 min for all the coupling caps & tone stack caps on an amp.

     http://www.el34world.com/Forum/index.php?topic=11427.0

2)  Build it with OUT the relay first and make sure it works.  Just use DPDT switches.  You can reuse them when the relays are hooked up.
     I think of the relay system as kind of a amp system in itself & prefer to get the amp right and then take on the "other" project meaning
     relays.   Given the nature of EL84's ...............   I would use just two relays probably.  I'd skip the PAB and maybe use the midboost
     & just the clean/OD.   IF you wanted a 3rd relay, ............ maybe some type of bright switch?

3)  I lean towards using shielded wiring to V1-3 and on all long runs.  After the amp works, go back and try removing some shielded wiring
     and see if it stays quiet.

4)  Take your time, quadruple check everything before firing it up.

5)  The D'Mars ODS, Tweed Overdrive and Tweed BluezMeisters should all be considered amps that you build and then tweak to taste.

I am rooting for you on this build and trust that it will be a good success for you.  Post pictures as you go,  Sluckey in particular is somewhat a ZenAmp master when it comes to noticing stuff that needs to be attended to.  Willabe is very good at it also as well as others.

This could be a GREAT alternative to the 18watt and voxish stuff out there.  Would be nice to have both a clean and OD at your calling.
Who knows .............. you could be paving a path that many others will want to follow?
 

[Glennjeff]

Have decided to put in a couple of octal sockets so that the output valve mixing idea can be explored. Have two taps on OT primary, 5.2K and 6.5K, which is close to perfect for the experiment. Great idea tubenit.

Point 1 .Cap Foil Orientation, wow, that's something I've never heard of, will definitely apply this.
Point 2 -5. Already on the list.

Thanks.

[Glennjeff]

My metal working is lousy but with great care I got some extra tube sockets in for The Experiments.

[tubenit]

6 preamp tubes?

 

With respect, Tubenit

[Glennjeff]

Just in case they are needed for some experiment in the future, like a valve compressor or to support some LCR EQ section or maybe as cathode followers in the "no silicon in my signal path paradigm" to replace mosfets.

I know a studio owner that is a bit that way inclined and may be trying to get him to use this amp in the future.

Putting an extra transformer in there for heater supply to free up a bit of current in the PT.

Just for fun and learning this one tubenit.

[Glennjeff]

Parts package arrived from Hoffman Amps today. Very nice.

In the meantime have installed a VVR although I managed to blow up a couple of nice industrial duty FETs in the process. Not sure why they arced across the leads, Drain - Gate, when dialling up from minimum voltage. Had a 12 V 5 watt zener in there initially, replaced that with a 1 watt zener and a 400V 10A FET and it goes fine. Will try again with a 500V 20A FET tomorrow, laying it out on its own little turret board instead of tag strip.

Then will tackle getting the PA built and running.

[Glennjeff]

Power Amp section worked fine first time. I thought it had a problem because it made zero noise when I switched B+ on. Had to put a balanced line into it to confirm it was going. Now for the LTPI, FX and PRE's.

[Glennjeff]

Lift-off to the red planet, WOW !!!.

Have only fired up the clean channel so far, got a 12AX7 in the front end and a 12AT7 in the PI and its like the front row of a zeppelin concert on 1. Starts off here at great overdrive rock sound and as you dial it up it just gets louder, more overdriven and sustains, feeds back and howls like a banshee.

Have built preamp to original 5881 spec with paralleled R's and C's so it will be easy to mod or switch.
Got some 3 position 6 pole rotaries which could make for a lot of experimental flexibility.

Tone stack is not doing much at all so it might be miswired. Tone is really forceful and meaty with a humbucker, a little too much top end sizzle for single poles at the moment.

Will try 12AY7 or even 12AU7 in front end and then get some sound clips up.

[Glennjeff]

Got the overdrive section going. Unfortunately did not have a 25 k pot for input to 5879 so used a 10k as the closest value on hand.

The overdrive is badly under driven and only adds a bit of pentode grit, which is nice in itself but will need to increase drive into OD section significantly.

Used 12AU7 as the first valve to get the front end cleaner so that's not helping the OD section either.

Sorted out the tone stack problem, it pleases me, which tone stacks usually do not.

Time to start tweeking. Will start implementing tubenit's recommended mods for EL84 setup.

VERY PLEASED with the results for ME, but want to get a generally useful design worked out.

 Will start posting soundclips tomorrow.

Hope you folks will help out with the tweeking.

All the best.

[tubenit]

The overdrive is badly under driven and only adds a bit of pentode grit

THANKS for keeping us posted on how this is unfolding!  Very interested in seeing what your success will be with EL84's.

Maybe pop a 12AY7 in V1 & try a 5751 in V2 (OD)?

Hopefully you can keep the 5879 pentode grit in check and smooth sounding while increasing the overdrive.  

To give you a reference point, I found it very easy to get notes to bloom into a very nice harmonic musical sustain with mine. Long sustain with rich harmonics was pretty easy with the D'Mars OD (using the 5879 there). I could dial the OD trim, drive and level to get almost a fixed "wah/vowel" tone also.

One tweak to experiment with is to add a 220p - 390p cap across the trim pot, or drive pot or level pot and see what that does to the tone and whether you like that or not?  (wiper to non grounded side).   Also playing with the values of the resistors to and from pots. You can decrease those and see what that does to the tone and overdrive. I think Geezer uses that approach frequently with some success.

With respect, Tubenit

[Glennjeff]

Getting setup to do sound demos.

[tubenit]

Wow!  That's a very very cool set up.  Tom Anderson and PRS. Nice choices.

Looking forward to the sound clips!

Fun getting the updates from you. 

With respect, Tubenit

[Glennjeff]

Start nice n pretty and work up to the death metal.

http://soundcloud.com/glennjeff/two-single-coils-on-the-edge

[tubenit]

That was very nice!  Thanks!  I liked it.

What were you doing from about 1:03 on ................ that in particular sounded very sweet and musical to me and had some warmth to it.

What guitar and pickup settings?  What was the guitar volume knob set at?

I am presuming the amp was on clean?  Correct?  What was the volume knob set at on the amp?

Were those the EL84's or another power tube?

Thanks for sharing it. I continue to follow this thread with some interest.

With respect, Tubenit

[Glennjeff]

Ummm, I never know what I'm doing, it just comes out spontaneously.

1:03 on.... Emi7 at 7th fret finger pick changing it to a Cmj7 with little finger on A string10th fret then using open position E shape first position (Emj) 2nd position but moved onto E A and D strings (Cmj7), back to E, then 4 th position (G13) probably threw in a 2nd position Fmj7#11 and then just did them all in random order quickly, let the B and high E strings ring as drone notes. (I think). Oh there may have been a D chord in same shape on EAD strings 4th position  as well (D6/9/11 ?)

Tom Anderson hollow drop top, neck and centre stacked singles in parallel.
Guitar was dimed, it's the Neanderthal ancestry.Maybe you could encourage/tutor me in the many uses of the guitar volume control.

Clean channel volume 3/10, that's the limit for clean on singles. 2 only EL84's.

I'm really happy with that sound.  Played tweakies with the OD channel all day, need to let my ears stop ringing before the results can be tested.

I'll explore and post as my fingers co-operate.

[Glennjeff]

That speaker system just does not cut it for guitar. I'll order in a speaker next week and get it in my empty 1 X 12 combo cab. In the meantime will practice guitar and get some backing tracks organised so the presentation is a bit slicker. Very rusty, have not played for 2 years, been learning drums.

Ran a conversion plug from 20 V to 200mV into the second speaker jack and recorded the whole amp as an FX pedal lined into the desk. Will pop up a metal cover with everything on 11 in a day or so. Never played metal before, with the strings so detuned they flop around like fence wire. It does have a strangely appealing harmonic aesthetic.

[Glennjeff]

Winged C 6L6's and TungSol 6v6's arrived today.

What an interesting palette to work with.

Pair of 6v6's with pair of EL84's is very interesting at volume as the EL84's are saturating but the 6V6's are still in clean mode.

6L6's are like smooth as molten chocolate, surprised that they have a lot less gain than 6V6/El84 double pair.

Have spent the day working on the 12AY7 part of tubenit's MoSo56 front end that is in this amp.
Refined the ideas about basically having a switching tonestack built into the preamp tube.

Successfully developed;

MID SCOOP:           With Centre Frequency and Depth options
BRIGHT / DEEP BOOST:      Either a small (3 - 5 dB) spike at 2K or 200Hz.

Have the standard BRIGHT switch across Pre Volume pot as well. This is pretty much a complete tone stack on the first valve.

Now need to sculpt the 5879 tone controls to compliment the 12AY7 as well as act as a contrasting standalone preamp valve. Thinking the mid scoop should move up to higher range of mid frequencies, DEEP could probably move up to 300 Hz   , might make the BRIGHT a PRESCENCE instead.

What set out to be an ultra neat build has turned into Dr Frankenstein's monster, nothing some gaffa won't hold together.  

All the best.

[Glennjeff]

Oh, by the way.

Who says tubes can't do metal. PRS 22 special, bridge humbucker straight into D'Mars EL84 and then into desk. (Yes of course everything except MID is on 11)

http://soundcloud.com/glennjeff/intro-dmars-stricken-metal

[tubenit]

Man, you are doing great with this build!  

Congrats on the success of your approach of blending the 5879 and the 12AY7. That is VERY cool!

I am appreciative that you shared the contrasting tones between the EL84, 6V6, & 6L6.  I don't know if anyone on the forum has tried all 3 of those in the same amp and then given the info about that they are different.  Very useful information for those of us that like to quasi design our own ideas.

Yeah, some of my evolving designs looked a little Frankesteinish also. Note that Geezer and I don't often post chassis photos. As long as the amp is quiet at idle and you can make sense of it to work on it, tweak it and service it ............. no big deal ....... IF it's your amp.

Whoa ............. the D'Mars ODS EL84 can do metal!  Not my favorite tone but I was impressed how aggressive  and intense the tone was. Pretty big sound from a reasonably small wattage amp.

THANKS for continuing to share your progress & success!   Maybe when you're done with the amp, you can re-name it something like the "Down Under Overdrive Special" or whatever you like. Or how about the "OZ  OD Special" or .............. maybe ........ ___________?

 

Do you have an "enhance cap" on the entry plate into the LTPI?   IF so, what value are you using?  Just curious.

With respect, Tubenit

[SILVERGUN]

Very interesting thread, backed up by some great demos 

Great to see the interaction of you two going back and forth,,, with this as the outcome

I dont think T saw himself designing metal amps in his retirement  , but it turns out that his input just results in a great amp no matter what genre

Nice work guys!

[Glennjeff]

SILVERGUN,

I haven't had so much fun since falling of a bicycle when I was 5. I'm retired as well, it's just there is something very cool, compelling and harmonic, about drop C tuning with a shitload of  tube overdrive. I think it actually sounds a lot "nicer" than off the shelf foot pedal stuff, you can hear into the naturalness of the sound, it's really quite organic.

IIRC you were going to explore breadboading PPICF's, can't find the thread, forgive me if I'm wrong but that was kinda interesting.

[tubenit]

Just as an FYI,  I'm not retired.  My dad worked til he was 79 yrs old, and I may do the same. Who knows?  3.5 yrs til I go down to part time (3 days a wk)  and then will take it yr by yr.

 

With respect, Tubenit

[SILVERGUN]

I think it actually sounds a lot "nicer" than off the shelf foot pedal stuff, you can hear into the naturalness of the sound, it's really quite organic.

I agree, and I think the tone you had on that Disturbed track was excellent......

IIRC you were going to explore breadboading PPICF's, can't find the thread, forgive me if I'm wrong but that was kinda interesting.

Yeah,,,,HBP wanted me to start with a pre built amp platform, and that's where my time has gone....getting the breadboard up and running has been a learning experience unto itself.......but I'm close and will be posting soon, will call it "the SS project".....glad to see it might be interesting to someone other than me
Also working on a better method of recording, since my first attempt was pretty embarrassing 

Just as an FYI,  I'm not retired.

I know....I've been watching the calendar for you
I like to think that the American Dream still exists
I was referring more to amp building retirement  ... and it's great to see you still interested and interesting!

[Glennjeff]

Finished with messy experiments. Pulled it down and started tidying up a allocating real estate on the front panel. There is a lot to go in there.

Nearly got 12AY channel finished and set up on the front panel. Need to fine tune it a bit.

Did some objective spectrum analysis testing today. For those so inclined - here is some chart porn.

[Glennjeff]

 12AY7 switching preamp pix, only 2 pots.

[Glennjeff]

Yay,

Got a very, very nice finished amp ( without faceplate for the time being).

It's got a few add on mods, quasi parametric mid scoop with CENTRE FREQUENCY and DEPTH switches (6 position), an extra treble control HIGH TREBLE CUT and a DEEP switch which adds a hump around 200 Hz.
The tone stack has a bypass switch also.

All of these mods can be switched out giving a stock standard D'Mars.

This amp allows one to select different output valves EL84 pair/quad or dual 6V6 or dual 6L6.
You can also run combinations of output valves 2 6V6's and 2 EL84, 2 6V6's and 4 EL84's are the combinations I have tried. I kinda like a pair of 6V6's with a pair of EL84's but have not seriously assessed the differences yet.

I have not tried it yet, but it should also be able to be loaded asymmetrically eg. 1 6L6 Pushing and a 6V6 and EL84 pulling, do not want to risk damaging the valves for the sake of an obscure experiment.

The distortion section needs some tweaking and option switches. Whilst very smooth and squishy/slippery, everything tubenit promised, I would like the option for it to be harsher and brighter as well. I would also like the distortion section to have the mid scoop quasi parametric options for added metal functionality. I've simply run out of real estate on the front panel, so it's going to be limited to a few mini-toggles.

I'll settle in with it as is for the present and get used to it.

Will post soundclips  over the coming days.

All the best.

[tubenit]

I'd be really happy with an amp that looked that good!    BRAVO on a great job!!  You have accomplished a remarkable project and I'm impressed with your innovation and gutsy-ness to try new stuff.  Very cool.

I don't know if you have a schematic that you can share or not, but would love to see what you finally came up with?

Very much looking forward to the soundclips.  IF you would, please, do some more EL84 clips with it overdriven. I'd like to hear what you've currently got going with that.

Regarding some more harsh and brightness. Here are some easy to try out considerations just clipping in caps (paralleled in some places).
The first of these I'd try is upping the power tube cathode cap to something like 100uf or 220uf.  This may sound somewhat counter intuitive but a larger cap there sometimes gives the audio perception of increased brightness (tighter sounding tone) along with increased bass.

With respect, Tubenit

[Glennjeff]

Well comparing valves proves to be an Apples versus Oranges minefield, however!


Clean Channel with Anderson H3 humbucker, volume and tone dimed.
Tone stack set to Bass 5/10, Mid 5/10, Treble 5/10, Bright switch on. No Mods switched in.


Running preamp at the very early stages of saturation, then adjusting the PI send till it is just beginning to saturate and then running the PA wide open, we get this;

http://soundcloud.com/glennjeff/comparison-el84-vs-6l6

4 Bars of 4/4 with EL84's then same phrase with 6L6's, spliced to be seamless.

The 6L6's actually have about 2dB less gain than the EL84's so a sound file comparison is a tiny bit incorrect. The 6V6's have a bit less gain even still, about 3.5dB down from the EL84's. That means the PI has to work harder to get them at the same volume, or even harder still to drive the big bottles to their full power. Starting to wonder about the relevance of PPICF's to this testing procedure. (PPICF's could be MOSFETS).

BOTTOM LINE.

The EL84 have a more trebly, brassy sort of tone and get to their limit with less drive.

The 6L6's are smoother, can be driven harder and of course produce about twice the power of EL84's.

For the type of music that this soundclip is representative of I prefer the EL84's on the recording, standing in the room with earplugs in, I prefer the 6L6's


OK, same preamp and Pi drive settings, this time comparing 6V6 with 6L6

http://soundcloud.com/glennjeff/comparison-6v6-vs-6l6

4 Bars of 4/4 with 6V6's then same phrase with 6L6's, spliced to be seamless.

Very hard to hear the difference with an mp3, but the 6V6 is even smoother than the 6L6, but once again, do the drive parameters allow a fair comparison.

(NOTE: I am reading dB's from my recording software's VU meters, I think this would be voltage not power so not a great deal of difference (1 to 1.5 dB power wise), although I found this quite noticeable)