65 amps lil'elvis/tupelo

[bruno]

I'm curious about these two little amps, they are basically the same, with the exception of different voltages/transformers on the tupelo, which has 6v6s instead of el84s! They have a great sounding bias modulated tremolo, and appear to have the same signature clear sound that the other models with the ef86 front end/cathode follower have.

Since they use 3 12ax7, I would say two triodes for PI, two triodes for the bias modulating tremolo (which kind I'm not sure), and what about the other two triodes? Do they have them paralleled, or are they using a second triode after the volume/tone section?

I'd like to have a go at this simple kind of circuit, and be able to get the same type of clear sound. I know these amps topology is nothing new or spectacular, but I really liked what I heard, very clear sounding cleans and distortion, very chimy. It would also be a nice oportunity to try installing a VVR, since this is a small cathode biased amp.

By the way which type of scalling do you guys go for with the VVR, power amp only, or phase inverter and power amp?

thanks

[tubenit]

Bruno,

My 5879 Blues Amp is a 6V6 version of the HoSo56. It's a nice amp.

http://www.el34world.com/Forum/index.php?topic=9049.0

Take a look at it and the HoSo56 thread in the SCH files. My 56T has a VVR on just the power amp and phase invertor.

http://www.el34world.com/Forum/index.php?topic=6176.0

http://www.el34world.com/Forum/index.php?topic=6833.0

You may prefer the boost switch technique that DaGeezer, CraigB  and some of the other guys use instead of the PAB type boost that I use.

With respect, Tubenit

[tubenit]

For a vibrato version of the HoSo56, look at the 5879 Carolina Blues Rocket that I built. I used 5881's but I could interchange with 6V6's without re-biasing. I made a vibrato version using a 6AU6 tube which is a vibrato I copied from an old Dano amp I loved. You could just use a 12AX7 like on the Vox Pathfinder and some Gibby amps.

http://www.el34world.com/Forum/index.php?topic=6368.0

I don't know about VVR and the bias vibrato?  Maybe that'd work?

With respect, Tubenit

[bruno]

hey thanks tubenit, I was actually looking at your schematics of the hoso, I might steal your dano vibrato and some other appointments on the hoso, definetly I will check your implementation of the VVR. However for the front end, I'd like to do something similar to the lil'elvis/tupelo, with simple tone/volume stack, but that could get the 65 amps type sound/clarity.

[tubenit]

Bruno,

I tried a 5E3 type tone stack (sort of) after the 5879 preamp tube. It worked fine.  You can do that, or use one of those
switchable coupling cap ideas for a tone stack.

OR ....... you can use a dual 500k pot and install a one knob James Tone stack after the cathode follower and still have a one knob tone stack but that has really excellent tone shaping.  Look at the Carolina Blues Special version using the James Tone stack for good starting place values.

With respect, Tubenit

[bruno]

excelent ideas, tubenit thanks, I will try those, I'm still trying to decide on whether to do this amp true point to point, or use an eyelet board... how are you liking the pentode at the first gain stage? I know you used to use paralleled triods in your builds.

[Geezer]

how are you liking the pentode at the first gain stage?

For me, it's really my favorite setup....ever! I just can't say enough how wonderful the 5879's are in V1 (even though the current amp I'm building is 12AX7/Dumble based  ... I was building a bigger/better HoSo, but don't see the need right now, the original sounds so good)

I am working on a "new" type of mid-boost to replace the original design, as I never use it, but find cranking up the mid pot more useful & tone-ful. I'll post when I get it installed (in several days, at the most).

Geezer

[bruno]

have you guys heard the new tupelo... it has a simples tone/volume and no pentode on the preamp, but it still sounds very open like the soho, however I might try the 5879 pentode.

[tubenit]

Like DaGeezer (genius that he is), I like the 5879 better than a paralleled 12AX7. Fatter and somewhat warmer tone, IMO.

It is chimey-r with a dash of crunch in the V1 position. In the T-Lite 5879 OD, it is in the V2 position as the overdrive tube. I actually like that even better. It is super super smooth overdrive.

With respect, Tubenit

[darkbluemurder]

I second tubenit's and Geezer's opinions. The 5879 works great as V1, and I continue to like my two HoSo builds.

Next thing I will try is to use the 5879 as V2. There are two possible candidates: my Chieftain build and my modified AB165 Bassman (this one has a D-style circuit which I could modify to use the 5879 in the overdrive section). BTW: the Dr. Z Rx ES has a similar arrangement (12AX7 gain stage - FMV tone stack + volume - EF86 - PI - PPIMV - PA).

But BTT: I believe the Lil' Elvis/Tupelo have the triode sections of V1 cascaded.

Cheers Stephan

[bruno]

regargind the tupelo, that would surely explain the amount of gain the amp seems to have, and why the amp sounds so lively in the pre amp section...

why do you guys prefer the 5879 over the ef86 for example, less prone to microphonics? Is there any modern production 5879 available, just out of curiosity?

[Lizard King]

I'm working up a two channel power amp based around the 5F6-A circuit. 

1) Would your vibrato circuit be suitable in this environment?
2) If I wanted to add adjustable bias, would I just build 2 of Doug's adj bias circuits, feed them both the output of your vibrato, send the output of each adj bias circuit to the bias input of the power amp sections?
3) OR - just forget about adding vibrato to something like this.

Thanks.

[tubenit]

Lizard King,

Your 5F6-A amp is not cathode biased. It is fixed biased. The Dano 6AU6 tremolo is for a cathode biased amp.

I'd recommend considering Hoffman's vibrato mods for a AB763 circuit which is also fixed biased. You can find the info in ARCHIVES here:

http://www.el34world.com/Forum/index.php?topic=604.0

With respect, Tubenit

[Lizard King]

Lizard King,

Your 5F6-A amp is not cathode biased. It is fixed biased. The Dano 6AU6 tremolo is for a cathode biased amp.

I'd recommend considering Hoffman's vibrato mods for a AB763 circuit which is also fixed biased. You can find the info in ARCHIVES here:

http://www.el34world.com/Forum/index.php?topic=604.0

With respect, Tubenit

D'OH!  I should have read more closely. 

I saw that thread and started to follow it but a couple of the schematics were off line.  I suppose I could use the Princeton vibrato from the AA1164 circuit.  Same question #2 would apply.  Would I build 1 vibrato and 2 adj bias circuits or 2 vibratos & 2 bias?

Thanks!!!

[bruno]

tubenit's sugestion is a good one I think, using the blackface princeton tremolo should work, you can also use the brownface bias modulated tremolo, that is similar, but uses two triodes instead of one (6G16 for example, I guess the 6G9 tremolux circuits also use something similar)... Both are good I guess, I really like the princeton tremolo!

[topbrent]

Here is a fuzzy shot of the guts of a Lil Elvis.

[topbrent]

More

[conger]

By the way which type of scalling do you guys go for with the VVR, power amp only, or phase inverter and power amp?

The "best" way to go depends a lot on the topology of the amp.  I have a Tweed Deluxe with the whole amp scaled which sounds fine.  With the 5E3 it is a bit more involved if you scale just the PA because you need to add a pot to limit the signal from the full voltage pre amp and PI into the scaled PA.  Also I think the reduction in signal level and more brown sound you get as you reduce the whole amp voltages in the 5E3 suits the character of that amp.

On the other hand, I much prefer scaling the PA and PI on 18Watt and Vox type amps.  In the LiteIIb for example, the volume control also acts as the way to reduce the signal to the scaled part of the amp, so no extra pot is required.

I don't know what the topology of the Tupelo/Lil ELvis is, so I can't really comment on that.  It is a most interesting sounding amp and I look forward to this tread developing.

[bruno]

Thanks for the reply on the 5E3 scalling experience...

also thanks for the lil'elvis photos, even though I can't personally take a lot of conclusions out... but the first two triodes appear to be connected either parallel or cascaded... then volume and another triode (gain stage or cathode follower), the PI appears to be long tail, and that leaves the tremolo with one triode? I could be way off, I can't really make a lot out of the photos.

[conger]

Leaving the Tremolo aside, anyone know what the topology of the Tupelo or Lil Elvis is?

[bruno]

I was actually trying to figure out as much as I could from the photo, I'm pretty sure the amp is quite simple, but it's hard to capture some essencial bits from the photo.

It looks like a triode, than a volume, than another triode, but I can't make out whether the tone control is wired with the volume or located after the second triode (but I guess they appear to be wired in an 18w fashion)... I also think the passive effects loop is right before the PI entry point, but everything around the second pre amp tube is one big mess in the photo, so I can't tell for sure whether the amp has both triodes of that tube being used for tremolo, or if one of them is being used like a cathode follower or extra gain stage.

PI seems to be, long tail.

[conger]

I can't see a conventionally laid out LTP in that fuzzy photo.  In one of the Tupelop of Lil Elvis videos they refer to an early 60's design that was long forgoton about.

BTW, that looks like a prototype more that a regular high build standard 65Amp.

[bruno]

There is no particular reason why it should be a prototype, all lil'elvis and tupelos are built using a small eyelet board, unlike the soho, which is a sort of true PTP, using small tag strips in some locations... other than that it looks quite similar to all other 65 amps I've seen inside, with the exception of the london, which is a little different and uses a turret board. There is even a video of the tupelo chassis filmed from the inside on youtube, and it looks quite similar to the lil' elvis on the picture above.

I suspect the tremolo could be similar to that used on some early gibson or ampeg amps, that had bias modulated tremolo and cathode biased output sections.

On further inspection you might actually be right about the PI, as one of the leads that comes from the PI to the coupling caps appears to come from the plate and the other from the cathode, along with the cap in the center of the socket, that could very well be a cathodyne inverter.

[conger]

There is no particular reason why it should be a prototype

It just looks like it was built by another builder and not by the high standard of build I have seen from photos of 65Amp chassises.

[bruno]

Honestly it looks like the regular 65 amps standards I've seen in any of their amps...check this link, it has a video of the third tupelo built, you can see the innards.

[The_Gaz]

Yeah, looks identical to one I saw in a review in some big guitar magazine. Then end of the video is interesting - about having 3 people check for bad solder joints. I imagine a lot of boutique builders get pretty paranoid about parts failing, and then getting a bad rep.

[tubenit]

Just an idea to consider.

I would personally probably try the dual ganged james tone stack because it is more versatile and it gets into the Marshall type tone (per Duncan Tone Stack Calculator & my experimenting). I only mentioned dual ganged because you stated you want one tone pot. I have done this before and it worked fine.

With respect, Tubenit

[bruno]

Hi tubenit, thanks for the ideas, I'm going to follow you on this one... unfortunately the transformers I have here are not the best for this project, I have a complete heyboer set for a brown vibrolux/tremolux... I'm going to trying buying something smaller!

I noticed you drawed the schematic with a cathodyne inverter, however feel I'm going to use a long tail, lately I've been playing with m ac15 twin quite a bit and I like the ef86 channel a lot with a strat, it's a dark sounding amp, and it has a great clean but can get quite nicely overdriven too. I think however I will have a hard time finding 5879 tubes here in portugal, which makes me wonder if I should try ef86s instead?

thanks

[tubenit]

Bruno,

While I like both the concertina and LTPI, I prefer the LTPI more.  If you're using the LTPI, then you'll need four 9 pin sockets. So in light of that, I'd use a full 12AX7 for the vibrato. I'll try to draw up something later, IF I can find the time.



With respect, Tubenit

[bruno]

Hi Tubenit, I'll try posting a schematic using your preamp ideas, next week... with the ltpi and two triode vibrato.

I've got a feeling I also might be using geezer's cathode bias atenuation idea.

Thanks

[tubenit]

Bruno,

Here is a schematic for you. I have done both DaGeezer's cathode attentuation system and a VVR. I like the VVR the best of all methods to control overall volume. It has the least change to my ears of anything I've tried when dialed down. The cathode attenuation method does work OK though.

With respect, Tubenit

[conger]

There has been plenty of talk about 5879 tubes, but the Lil Elvis and Tupelo do not use them.  It uses 3 12AX's.

So are we any closer to determining what the circuit is?  One this is for sure looking at the chassis picture - there is an unusually high number of signal and power caps in the build.

[bruno]

I was curious about the lil'elvis and the tupelo, but now that I ended up going through some old amp schematics with similar features,  I don't think it's really that important to determine what the circuit is...

I much rather play with some of the circuits tubenit posted here. And maybe set up a little working chassis where I can try some of my own values and test some of those features.

Since I have the tremolux iron set laying around, I might as well use it a go for a pair of cathode biased 6L6s!

Let's see what I can come up with.

[jojokeo]

While I like both the concertina and LTPI, I prefer the LTPI more.  If you're using the LTPI, then you'll need four 9 pin sockets. So in light of that, I'd use a full 12AX7 for the vibrato. I'll try to draw up something later, IF I can find the time.

With respect, Tubenit

Can you describe what it is that's different between the sound and feel between these two pi's? Thanks, as I'm teetering on whether to use another gain stage (and therefore tube) for a LTpi if it makes a huge difference to warrant the extra tube or not.

[tubenit]

I built a Carolina Blues Special with concertina and then left everything the same that I could and tried it with an LTPI.
The LTPI seemed more touch sensitive to me.

With respect, Tubenit

[bruno]

in order to answer conguer, I suspect that 65 amps, based their amp design in the 60s vox pacemaker, and improved it a little...
I could be totally off though!

[topbrent]

in order to answer conguer, I suspect that 65 amps, based their amp design in the 60s vox pacemaker, and improved it a little...
I could be totally off though!

Here is a gif of the pacemaker schem that is floating around the net.

[conger]

in order to answer conguer, I suspect that 65 amps, based their amp design in the 60s vox pacemaker, and improved it a little...
I could be totally off though!

Cool.  That's an interesting amp and just shows how creative Vox were.  I wasn't aware of that amp so thanks for pointing that out.  Also good to know that there is a cathodyne PI EL84 amp from back in the day.

[bruno]

Hi, it's just a hunch, I've had, but I could be totally wrong, 65 amps tells us that they rediscovered this lost amp/schematic of one of the early 60s greats, but they never tell us it's a design that was never put into practice. Well the pacemaker is indeed a lost amp, from one of the big 60s guys... vox. It's hard to find an original one and when you do they are generally the solid state version!

I know the pacemaker schematic is a bit off in some points, but it could very well have been used as a good starting point. Another lost amp which could very likely have been used as an inspiration (with it's 12w-el84s) is the vox pathfinder V101, unfortunately a schematic is nowhere to be found.

[conger]

It's a good hunch.  I often wondered why there were not many cathodyne PI EL84 amps and I assumed it was because the LTPI was the new design at the time and it got lost in the pursuit of the various marketing led decisions that occurred since the early 60's.

[bruno]

an extra bit of information is that I believe the new tupelo... is not tube rectified! If you notice the youtube video filmed at the 65 amps factory, you can see that the hole for the socket is there, but there is no socket.

[conger]

Premier Guitar has a nice review of the Tupelo (at http://www.premierguitar.com/Magazine/Issue/2010/Sep/65Amps_Tupelo_Combo_Amp_Review.aspx) and there is a photo of the inards.



Anyone figured out what the circuit is yet?

[Geezer]

One thing I spotted in that pic is a mosfet for a VVR! 

[tubenit]

There would appear to be an error in Tubenit's schematic upthread...

The anode of the upper 1N4007 can't connect to ground & have the cathode supply preamp (eg; 240v+/-) voltages

I'm not following what you're saying?  Where do you see an anode of a 1N4007 connected to ground?

Can you post what you feel would be a corrected schematic?

The schematic I posted was hypothetical but the B+ & VVR topology is based on actual successful amp builds that I have done.

With respect, Tubenit

[eleventeen]

I misinterpreted, Tubenit, my mistake, thus yanked my post.

Because of the lack of a dot on the connection, below the word "low" on your dwg, are 2 qty 1N4007's. The anode of the diode serving the preamp stages at first appeared to be fed from ground thru a 220K resistor. Would be tough to get 240 volts out of that!

The 220K is the bleeder for the B+ and the preamp diode's anode is fed from the proper place. I misread it.

False alarm.

[fuzz]

hi,

don't know if there's any interests left but here comes my first guess on the lil elvis/tupelo preamp topology. Some new picture came out so I tried to do my best.



the difficult part is the tinny veroboard circuit with extra components. Some old version had a simple keystone lug board but they're not allowed to use this (according to Boul) . So I tried to think what the connections could be. As the amp doesn't appear really gainny even with 4 gain stages I gues that the parts on the verboard were used as a voltage divider and a bypass cap.

I couldn't give value to the resistor because I'm not familiar with carbon comp even if I think that anode resitors are 100K .

The fx loop desing is really poor though.

Anyway , as it seems that those amps are hard to see in real life that's all I got unless I find more pictures.

[TIMBO]

Good work fuzz, There is a lot of 5E3 and Pacemaker influence and is a fairly simple circuit, but its the component values that may give it an edge. Anyway I had a stab at it and if anyone can add to it might be a good build. 

[fuzz]

I was watching one of the recent Boul's lunch talking about the lil elvis and actually I forgot a thing . The so-called "radar circuit to fatten up the sound" (Boul's quote) desinged by Derek Underdown (old vox designer). I  don't expect magic tube circuit or voodoo wiring but it stays unknown so far.

Strangely enough Boul talked about a "cathode follower" , the radar circuit and the tremolo modifying the "radar" tube . The cathode follower and the "radar triode"  are certainly the veroboard circuit. Beside 4 gain stages don't seem right, the amp isn't that gainy apparently.

Values can be read I guess if you're familar with carbon comp resistor (which i'm not) , anode's resistor must 100K .

I hope one day I'll get my hand in one of them or someone will have the opportunity to draw the schematic.

[jojokeo]

I edited the highest resolution pic to brighten it up to see the dark areas of wiring better and added a touch of contrast so that the resistor colors are a bit more pronounced. Those tan colored resistors are read just like the carbon comps using the three bands away from the Red then White bands as those are simply for tolerance ratings. Ex: brown black yellow red white = 100K

The vero board looks to be actually just perf board. There's no traces underneath. Usually vero board or similar that has traces on the underside has white lines on the top side to assist in identification and for parts placements. The parts I can see on the perf board starting from the back are a silver micah cap, 22k, 10k, 10k, 100r, then the screw followed by .02uF, and .01 caps if this helps?

Keep up the good inspector Cluezo err Tupelo work!!!

[TIMBO]

Thanks jojo, Just to do your head in a bit more there is another resistor/s tucked under one of those caps you mention.  you can just see a white band poking out.

This project tweaked my interest as I have an 18w PT and OT that I was saving for that "special build" and again the HYPE that amp builders try to sell there amps with the TAG of a long lost schem that is to die for, sucked me in.

BLAH..... I'm not saying that these amps aren't great, everything about them top notch and with a price to suit, BUT..........
I don't see anything "special" about the circuit and I think its another case of starting with a tried and true schem and adding a touch of "seasoning" to taste.

The perf board is the stumbling point and unless someone can get hold of one, its too hard to trace.

This is what I could find.....
V1a - normal input values
V1b - tremolo circuit - much the same as any used in other amps
V2a - Typical gain stage after 5E3 type tone/volume controls
V2b - this is the hard bit and if you can nut this out, you get a pat on the back
V3a - another gain stage with the "BUMP" circuit which is switching between two sets of cap/resistor values
V3b - cathodyne PI, much the same Vox/Fender
And the rest, same old same old........ 

There is also a Trainwreck (blues express) flavour to this amp and wanting to use these transformers might be a good build.
To be continued?????????............................