Which 15-20W amp has most clean headroom?

[acheld]

I'm looking around for a new build, and want to maximize headroom.  Clean tone is king for this project.

I love my DR, but would like clean to extend beyond 5 on the volume scale.  This would be intended for gigging in small venues, with a jazz ensemble, as well as practicing at home.   

Recent Bassman build had great tone, but far too heavy and too loud.  Sigh, I do like those 5881's though.   

What would you build?

[Willabe]

Which Bassman?

What speaker is in your DR? Is it a single 12"? What's the dB rating of the speaker?

[acheld]

Hoffman 5F6.

Two 10" Weber speakers, a 10F150 and a 10A125.  They don't spec the SPL, so I don't know.   I tried with one speaker at a time, and it is more manageable  -- I do like the 10A125 (Alnico) tone much better than the 10F150 (which is also louder).  Very good question to ask, and often overlooked.   Yes, I would look at other speakers.  I'm always partial to Celestion alnico . . . have several, but have not tried them in this big rig. 

Also built an M2 attenuator, which works well with this amp -- but all in all this is not the right path forward for me.  Too loud/complex for home use, too big for this old back to lug around.    Quest forth!   

[Willabe]

What speaker is in your DR? Is it a single 12"? What's the dB rating of the speaker?

     

[acheld]

Ooops . . . my bad.

My DR has two 10" Celestion Gold G10 in parallel.  Sensitivity is stated at 98dB. 

[Willabe]

Tweed Bassmans are heavy mainly because of the transformers and 4x10" speaker cab. It was a bass amp, so they used larger iron set. Larger than their 2 x 5881 guitar amps.

I don't know of any 15w to 20w guitar amp that has more 'head room' than a DR. 

You might try looking at old Ampeg combo amps? They were clean. Some of them used different power tubes than 6V6/6L6, but they make some of those tubes again.   

How much more clean volume do you think you need? Some guys find that they can get enough of a little more clean from an amp with a very efficient speaker. Or if they use 2 very efficient speakers.

They make oversized OT's for many tube amps, they make them for DR's. They stay cleaner longer, but if your tubes are distorting, a larger OT probably won't help. Hard to know until you try it. An oversized OT in my little Champ made a difference. 

With both a 12" (or 2 x 12") efficient speaker(s) and an oversized OT, it might be enough, but it will cost you to find out.   

Other than that, to get more clean you need more power. And more power means larger iron set with bigger power tubes.

Fender made a tweed Pro amp that was ~30w, 2 x 5881's, with a single 15". Might be an option? Fenders next up was 35w amps with either 1 x 12" or 2 x 10" speakers. The iron set in those is not too bad in size and weight.

[Willabe]

My DR has two 10" Celestion Gold G10 in parallel.  Sensitivity is stated at 98dB.

That's not great, for example, Eminence Red, White and Blues, 101dB. I think they make speakers as high as 102dB, 103dB?

Some of those Neodymium mag speakers are very light weight and have very hi sensitivity? Some guys say they sound great? 

[pdf64]

Yey, ‘headroom’ as a multipurpose descriptor of nebulous, indeterminate actual meaning strikes again 

[Willabe]

Agree, but I think he wants a little more clean volume.

[HotBluePlates]

Which 15-20W amp has most clean headroom?

I'm looking around for a new build, and want to maximize headroom.  ...

Trick Question??  They all have the same amount of "headroom": 15-20 watts.

I love my DR, but would like clean to extend beyond 5 on the volume scale.  ...

The Deluxe Reverb is ~22 watts, so "higher headroom" than your proposed range.

If the DR gets loud enough but you just need ability to turn the Volume control higher, use lower gain 12A_7s in the preamp.  12AU7 in place of a 12AX7 or two will force you to turn the Volume full-up to get dirt.  The amp won't be any louder though, still only ~20 watts.

Does the Deluxe Reverb distort before it gets loud enough?  If yes, you need more like 35-40w.

Hoffman 5F6.

So you're saying you already have "louder than a DR."

What exactly do you need the new amp to be again??

Agree, but I think he wants a little more clean volume.

I suspect there is an unstated requirement here.  "More Clean Volume" is already available from the Bassman.

[Willabe]

I suspect there is an unstated requirement here.  "More Clean Volume" is already available from the Bassman.

Also built an M2 attenuator, which works well with this amp -- but all in all this is not the right path forward for me.  Too loud/complex for home use, too big for this old back to lug around.

[acheld]

I suspect there is an unstated requirement here.  "More Clean Volume" is already available from the Bassman.

As noted, the 5F6 is too loud (without the attenuator), and too heavy (with or without the attenuator) to carry around.

My DR is a great amp.  No, I don't need another amp, but I do need a winter project. 

I was thinking of something like a Princeton Reverb but with 6L6 in the power section.  Something different than the DR.  I have a bag full of 5881, 6L6, and some Russki military tubes -- I'd like to use them if I can, but if I need to stay in the 6V6 world, I'm fine with that too.

I did look at 5E5 briefly -- seems interesting.

No hidden agenda here.   I'm hunting for a project.   And I appreciate your experience and knowledge . . .

[SILVERGUN]

I think it would be as simple as something like this:


I would do this in Doug's stout chassis and just make it a small 1-10" or 12" combo

[sluckey]

This may be of interest...

     http://sluckeyamps.com/phoenix/phoenix.htm

[jordan86]

I will echo others’ suggestion that a Blackface Deluxe Reverb is about as good as it gets in that field. To eek every last bit out of it you can upgrade transformers, get a high efficiency speaker, solid state plugin rectifier, and try 6L6’s. It’d be a sorta strange endeavor though to want to build something between your DR and Bassman. Probably just easier to to tweak one of those to be a louder DR or quieter Bassman.

Silvergun had good mod suggestions. Smaller bypass caps would clean up your low end and come across as staying cleaner longer. I think everything you need is already there in your DR though. Just need to tune it to your liking.

[dwinstonwood]

Naturally, I recommend one of these: http://sluckeyamps.com/misc/AA864_Musings.pdf

Here's my thread: https://el34world.com/Forum/index.php?topic=26289.msg287322#msg287322

I ended up with a 5751 V1, and a 12AT7 PI. Very clean with a full frequency response.

[glass54]

Hi acheld,
I'd go with a Princeton Cabinet, simple Preamp/Amp (as per Silvergun), BUT you might find Sluckey's Phoenix most flexible giving you the choice of preamp styles. I'd keep the power supply in the 425V range, (Phoenix has the more appealing Power supply), making sure the heater current rating of Power transformer can handle 6V6 and 6L6. You might also consider a SS rectifier (??). I would definitely use a LT Phase Inverter, to obtain cleanest drive to OP Tubes and probably choose an output transformer good for 20-25W. You can always attenuate the the signal prior to LTPI to avoid excess level. +1 with comments made by HotBluePlates regarding 12AU7.
I think we all look forward to the results of this project
This all should fit easily into a Princeton Cabinet and you'll have space for a 10" or 12" speaker option. And you would also have an amp weighing a little heavier than the Fender Princeton but lighter than a Deluxe Reverb 
Kind regards
Mirek

[acheld]

Well I really appreciate the time and effort put into these comments and suggestions.   Now comes the hard part of figuring out which road to travel.

I admit I've always been intrigued by Sluckey's Phoenix, but enjoyed watching the AA864Musing project come together, and appreciate Silvergun's thoughts, and Mirek's summary. 

So I'm going to print all these schematics and give it a good think.   I've learned to have a plan before starting work . . .   This may take some time, but I will report back.

[dwinstonwood]

acheld, here's the final docs with sluckey's artful layouts and a few additions to the schematics.

[Fresh_Start]

This may be of interest...

     http://sluckeyamps.com/phoenix/phoenix.htm

That’s a cool project!

[mresistor]

A Princeton Reverb using David Allens TP25H PT and a good Deluxe Reverb OT is a good candidate.  Using that combo you can run 6V6, 6L6 or EL34.

[MWaldorf]

A bit late to the speaker part of the discussion, but speaker efficiency does wonders for headroom.  For 12" speakers I'd recommend the JBL D120 or the Celestion Blue (or whichever is ext up in powerhandling).  If you like 15"s, a JBL D130 is a great speaker.  I've got one in an Ampeg Gemini I (20W) and it gives the amp more volume, clarity, and, for lack of a better term, authority.  For 10s I've used the Celestion Golds, which sound great but are less efficient that the equivalent 12" versions.

[acheld]

A Princeton Reverb using David Allens TP25H PT and a good Deluxe Reverb OT is a good candidate.  Using that combo you can run 6V6, 6L6 or EL34.

Oh this sounds like fun. I have a Princeton Reverb board on my workbench . . .

David Allen stopped selling transformers, but Hammond 290BX, 290CX, and 290DX are all in the ballpark for this purpose.  I'll have to look more closely at the specs to decide which would be best.  At this point, I am weight conscious (not for myself - that ship has sailed, but for the amp).

[mresistor]

David Allen stopped selling transformers,.

I'm sorry I had no idea..  I thought he was getting his tx's done with Heyboer. I wonder if Heyboer experiencing problems.  Hope it is just temporary..


I love my PR in that configuration.. it's really great for single coils and jazz, blues playing .. 

[acheld]

Allen did stop, but he left up the specs of his transformers, of which I have several (for EL84 amps).  So all is ok, and easy enough to look through the Hammond online product list for guitar amplifiers.

Appreciate the pointer!

[faraday]

A Princeton Reverb using David Allens TP25H PT and a good Deluxe Reverb OT is a good candidate.  Using that combo you can run 6V6, 6L6 or EL34.

Oh this sounds like fun. I have a Princeton Reverb board on my workbench . . .

David Allen stopped selling transformers, but Hammond 290BX, 290CX, and 290DX are all in the ballpark for this purpose.  I'll have to look more closely at the specs to decide which would be best.  At this point, I am weight conscious (not for myself - that ship has sailed, but for the amp).

I'm still pretty new at this tube amp business, so don't read too deeply into my comments. But, after finding the aforementioned upgraded, drop-in iron on Allen's web site a couple of weeks ago, I've decided on a Princeton Reverb project for this Winter, but with a simpler tremolo and the reverb delete circuit. The circuit that I've settled on is the Trainwreck Rocket, but with a pair of output tubes, rather than the quartet of EL84's. I'm leaning towards 6V6 output tubes, but with the upgraded transformers, I haven't as yet ruled out 5881's.

The Rocket is the tame one in the Trainwreck roundhouse, which doesn't even have a bypass cap on the V1B stage. But, at the end of the day, not being bothered about building a clone, I can make it as clean, or as dirty as I wish.

You'll notice that this circuit will leave a 9-pin socket open, so If I go the dirty route I'm pretty sure that there is enough room to squeeze one of @tubenit's one-triode FX loops into the Princeton chassis.

Food for thought.

Cheers!

[jordan86]

David may have transformers if you buy a kit, like the sweet spot. But can’t say for sure. The Princeton would be a great size, but you’d definitely have to go 6L6 if you want more headroom than your deluxe. I built my own 1164 Princeton last year with a 290AX, Allen’s TO20B, and the stokes mod. With an efficient speaker it hangs with a deluxe for sure, but doesn’t have MORE headroom.

Something like Fender’s 68 Pro Reverb Reissue may be the right size. It’s also very akin to the JHS louder is more good. Something in the Princeton/Deluxe (non reverb) cabinet form factor. Single channel ab763 with 6L6. JHS amp is stupidly overpriced thanks to milkman being involved. Could build one for way cheap.

[sluckey]

Don't lock in on anything without considering the Princeton AA964. Just like the PR but without reverb...

     https://el34world.com/charts/Schematics/files/Fender/Fender_princeton_aa964_schem.pdf

[labb]

I built a Princeton Reverb with Reverb and tremolo omitted for a friend. Up graded the pt and ot to the deluxe xformers. He loves the amp. He is very hard to please

[acheld]

I like this idea.  Reading over the AA964 schematic, it is very simple, straight to the point.  With a different PI than my Hoffman DR.

May drop in a DR capable PT and OT, which should allow some experimentation with 5881 tubes (of which I have many) vs 6V6.

[jordan86]

I really wanted to build an AA964 for my first amp but didn’t know enough at the time to deviate too far from a schematic and layout. So did the 1164 w/ reverb.

My only “disclaimer” would be that the 1164 can probably do anything the 964 can do and then some. An 1164 on 5 is about as loud as a 964 on 9. So you could say you get more for your money with the 1164?!? At least that’s what I’ve been told. I’d love to hear countering opinions though.

[acheld]

An 1164 on 5 is about as loud as a 964 on 9.

That is precisely what is appealing to me.  That fact jumped right off the schematic!

That said, when I get some free time, I'll be re-working the schematic a bit.   I won't stray too far afield, but I need to give it some thought.  As always, the issues are:   

1) What do I need?
2) What do I want?
3) What is the tradeoff?

[dwinstonwood]

Hi acheld,
Last winter I "grafted" together the AA964 with sluckey's AC15. It's about as simple as I could make it, having just a six-way tone selector and a volume control. I play it a lot.
Anyway, here's the schematic, FWIW.

[Willabe]

Reading over the AA964 schematic, it is very simple, straight to the point.  With a different PI than my Hoffman DR.

The Princeton has the concertina/split load PI, the Deluxe, has the long tail PI, LTPI. They sound a little different when pushed.

Yes I remember this thread is on most headroom, but; Look at this tweed Super, 5E4A, it's the model before they upped the tweed Super to 6L6G's in the 5F4. I wonder if those are really 6L6GB's/5881's? It has a split load PI with a pair of 6V6's. You can get clean tone from this amp;

https://el34world.com/charts/Schematics/files/Fender/Fender_super_5e4a_schem.pdf

The Fender tweed 5E _ line has the split load PI, they went to a LTPI with the 5F_ line. Rory Gallagher's tweed Bassman was a 5E6, not the latter tweed Bassman that Marshall copied and many guitarists still rave about, the 5F6-A. Rory did always use a Dallas Range Master Treble Booster into his amp (he later switched to using a Treble Hawk booster). That's a key part of his tone. You can hear it on Irish Tour live album;

There's a few Gibson amps that are very similar to the tweed 5E_ line. The tone controls are different, but otherwise their pretty close. And any of the 6L6 amps could be made to use 6V6's by changing the PI's drive and lowering the B+ PSU.

https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga70.pdf

I built a GA77 clone and I love it.

https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga77_vanguard.pdf   

More on Gibby GA70's and GA77's here;

https://el34world.com/Forum/index.php?topic=27456.msg279790#msg279790

[Willabe]

Another thing for more clean can be upping the preamp tubes B+ plate dcv.

Fender SR's had 270dcv on the input tubes. More than any of the other Fender BF amps. Fender BF Twin schematic shows 260dcv on 1 channel and 250dcv on the other. All the other BF amps the preamp tubes had lower dcv's.

Those 2 amps were the cleanest in the BF line up.

[glass54]

Picking up Jordan's last couple of posts and Willabe, I was after a smallish but clean amp, decided to go with a 1 Channel AB763 in a Princeton cabinet.
I wanted a Mid control, had a custom (Australian made) toroidal Tx for Power and Classic Tone 40-18087 output Tx, therefore I settled for my own homemade chassis, since a standard Princeton chassis cutouts didn't suit me.
I used a turret board (Hoffman AB763-1 CH built by Doug), worked really well and SS full bridge PS (fairly stiff). The Preamp DC voltage (Node D on Hoffman Schematic) to input Tube is approx 345V at idle. Sluckey's Pheonix shows 319V DC for the Preamp tubes (Node D)
HT was only +399V DC, would have preferred 420V. There is little sag at maximum output (less than 20V DC on HT) and the amp is capable of 21 Watts of clean sinewave (1kHz at into 8ohm Dummy Load). The speaker is a common variety NOS Fender 12" Part number 121042. Probably not everyone's "cup of tea" BUT there is no mistake in the sound ie clean Fender Deluxe Reverb thru and thru 
Next time I'd possibly delete the Reverb and do an active FX Loop?? More Flexibility?? More like Silvergun's thoughts ??
A few thought and couple of photos attached.
Kind regards
Mirek

[Willabe]

Very nice work.   

[acheld]

Your build is gorgeous!  I do have a DR which I love, and is played every day.

I'm probably going to build a Princeton AA964.

If it is possible without adding too much weight, I'll "upgrade" the iron so that I can throw in some 5881 power tubes.

Speaking of which:


TR 1                    Shipping Weight   B+ Volts     B+ Amps   Bias   Htr  Amps   
Hammond 290AX   2.95 lb           297 -  702      100mA     no     2.25A
Hammond 290BX   5.32 lb           660                138mA     50V   3A   
Hammond 290CX   6.8 lb             650                207mA     50V   4.5A   
Hammond 290DX   8 lb                650                230mA     50V   4A   

TR 2                   Shipping Weight   Input Imped   Output Imped   Output Power
Hammond 1750E    1.1 lb             8500 ohms       8 ohms            15W
Hammond 1760H   4 lb                 6600 ohms   4, 8, & 16 ohms   20W
Hammond 1760J    4 lb                 4000 ohms   4, 8, & 16 ohms   40W

So, the stock iron (290AX + 1750E) is about 4 lbs total -- this is probably not adequate for 5881 tubes due to current requirements, should be ok at idle, but marginal at max plate current @360 V.  I suppose if I kept the voltage up in the 400V range, I could keep the max plate current down and it would be ok.

The 290BX should squeak in ok.  My self-confessed "build it like a brick shithouse" tendency wants to go with the 290CX despite the extra 1.5 pounds.   (This is precisely why I do not build airplanes).

I think the OT should be OK with 1760H.

[glass54]

acheld,
If it was my amp, I'd definitely go with the 1760H (lots of benefits esp since your goal is cleanliness) and the 290BX is more than adequate worst case ie 2 off 6L6GC or 5881 max Heater current at 1.8A/pair leaving you 1.2A up to 4 off 12A-7 tubes
The 290CX would give you approx 50% more current capacity in HT (Stiffer Power Supply??) More robust ? (Like me, "Over the Top")
With the AA964 I would consider using 0.047uF (47nF) caps for Output Tube grid coupling, instead of 0.1uF. Sluckey and others might want to comment on this, as I believe this would make the amp "tighter" (Cleaner??)
I would also consider using the new node indicated on attached sch for the phase splitter. (Yes I know, don't fix something that's not broken, BUT we're here to learn and have fun  ) This would also give you a higher DC at Input Tube.
Kind Regards
Mirek

[jordan86]

If you want more headroom than a deluxe, my gut says the 290BX/1760H will not get you there with an AA964 circuit. It will probably be a fantastic amp though. Just not any more headroom. For sure do the PI/stokes mod with the unused node.