New Amp Build Input

[Tbone55]

Hi Everyone,

I'm looking for some input in determining a new amp build.  I have a quarter stack cabinet I built for 2 x 12" speakers and would like to build an amp for it. The cab is 8" deep and 17 3/4" wide I'm thinking the amp should be a head unit so I can utilize it with other cabs. I currently have a Blues Jr III with the Hoffman conversion and a Trinity Tramp. I'd like the amp to be in the 15w to 18w range and also have an fx loop.

I have been going through the list of Hoffman builds and those on Sluckeys website and there are a few that might fit the build but in all honesty I really don't know if I know enough about amps to choose. A plexi type build might be the way to go considering what I already have is the best I can figure so I have a different flavour.

While I've built both my amps I am in no way anywhere near the knowledge level of the folks on this forum. I have some basic understanding and know how to follow instructions and solder. Depending on the build my biggest hurdle will be the chassis. It has to be something that can be sourced,  preferably with all the necessary cutouts. The turret board should also be available.

When I read through some of the build posts on this forum the level of knowledge, help and patience is incredible. Believe me I know, as I'm sure I've tested the patience of a few members 😁. I'm trying to order Merlin Blencoe's books from Amazon US as Amazon CA doesn't carry them but for some reason the page to checkout won't load.

Enough of my gibber jabber. Thanks everyone and Cheers!

[bmccowan]

Based on your wants, I think a Plexi 6V6 would be a good choice.
Both Doug And Sluckey have proven schematics and layouts.
Doug has your board and your chassis.
I built mine with scrounged Hammond organ iron, but the proper iron is easy to source.
Best of all, its a great sounding amp.

[Brownie]

I used that schematic and info from Mark Huss/Steve Luckey on the 6V6 Plexi last winter. Our build is full sized in a Marshall size chassis though. Buddy loves his Plexi head

[HotBluePlates]

... I'd like the amp to be in the 15w to 18w range ...

Copy the power supply and output section of any 15-18w amp.

Normally, I'd also include "phase inverter" as a piece you should copy, but that will likely fall in the next section:

... I'd like the amp to ... have an fx loop. ...

An Effects Loop only makes sense in a master-volume amp.  Therefore, swipe the preamp (and its power supply) from any master-volume-amp you like.

   -  That's because the point of a loop is to place some effects after the distortion (that's being generated in the preamp).
   -  A vintage-style non-master-volume amp (including a "Plexi") distorts at the output tubes first, meaning distortion is "after the loop."

   -  There are products like the AmbiKab and Power Station that effectively put the effects loop between the amp & speakers.  However, they're both pricy solutions.

[Tbone55]

Based on your wants, I think a Plexi 6V6 would be a good choice.
Both Doug And Sluckey have proven schematics and layouts.
Doug has your board and your chassis.
I built mine with scrounged Hammond organ iron, but the proper iron is easy to source.
Best of all, its a great sounding amp.

That's definitely one of the builds I'm gravitating to. Doug doesn't carry the transformers for it anymore but they can be sourced elsewhere. I'd have to check the dimensions again to see how big it will be since I want it to fit on top of the cabinet I have. I'd really like to build an fx loop into it but I don't think I have the ability to do that unless there's a schematic that shows how to incorporate it into the build. I'm hoping someone on the forum has done this already.

Thanks Kindly for your input. Cheers!

[Tbone55]

Thanks for your reply HotBluePlate.

As usual, your response is very helpful. I don't know if I want to get into piecing together the different circuits together to make the amp I want. I'm more inclined to try and build something that others already have. At least that's what I would like to do. I did try to look at various amp schematics and was reading a post that tubenit started about his fx loop but I get lost in the discussion when the more technical aspects are discussed. From what you're saying it sounds like the only way to build what I want is to try and piece it together myself and then get feedback from the pro's on the forum.

Appreciate your help. Cheers!

[HotBluePlates]

... From what you're saying it sounds like the only way to build what I want is to try and piece it together myself ...

Certainly not "the only way."  But it is a way that will work.

IMO, anything that has "Plexi" in the name is the wrong move if you must have an effects loop.  Plexi Marshall amps were non-master-volume, so the distortion (if generated by the amp) ha[ens after any effects loop.  As I said, the whole point of a loop is to place reverb & delay after preamp distortion (rather than distorting the delays & reverb).

[Tbone55]

Thanks BluesHotPlate,

I was thinking about something along the lines of a Marshall DSL20 that has an effects loop in it. I'll have to look at a schematic for it first to know for sure. Are their any other amps you would suggest I look at as possible candidates? I know Slucky has some good ones on his site and Doug has a few as well.

Cheers!

[HotBluePlates]

Unfortunately, master-volume amps aren't my wheelhouse.

[Tbone55]

Unfortunately, master-volume amps aren't my wheelhouse.

No problem. Doug's Plexi 6V6 looks like it would fit the bill. It has a master volume and Doug has all the components available including the chassis.  I'd have to figure out how to add an fx loop to it.

There's another build I was looking at as well that has the fx loop in it that looks good but I'd have to find a chassis and make all the holes. I think Doug can provide the board.

Cost is another factor I need to consider. I get nailed with a big conversion factor on Cdn$ as well as duties. I can source stuff here but not in just one place. Doug is basically a one stop shop that makes it easier. That's why I bought the Blues Jr conversion kit from him, plus, his build instructions are top notch. Even a dumbass like me can follow them. 😂

Thanks for your help. Cheers!

[bmccowan]

Since I had initially pointed to the Plexi-6V6 I'll jump back in. Love the amp - mine does not have an effects loop. I trust HBP's experience that it might not be the best marriage. But, this thread has some discussion of the topic: https://el34world.com/Forum/index.php?topic=31906.0
I've only built 2 amps with fx loops - a Tubenit SoLow (7 watt push pull) and a 6V6 version of the Matchless Clubman which is another really good sounding amp that fits your power range of about 16 watts.

[Tbone55]

Since I had initially pointed to the Plexi-6V6 I'll jump back in. Love the amp - mine does not have an effects loop. I trust HBP's experience that it might not be the best marriage. But, this thread has some discussion of the topic: https://el34world.com/Forum/index.php?topic=31906.0
I've only built 2 amps with fx loops - a Tubenit SoLow (7 watt push pull) and a 6V6 version of the Matchless Clubman which is another really good sounding amp that fits your power range of about 16 watts.

Thank you kindly for chiming back in. I appreciate getting information to help me decide what to build. It's not something I want to just jump into before I've weighed out the options.

Maybe I've misunderstood what HBP was referring to regarding the effects loop. I thought he said that the amp should have a master volume control to make use of an effects loop and that Plexi designs don't have a master volume control. Dougs Plexi 6V6 has a master volume control plus it uses 6V6's, not EL34's.

There was another amp I saw on the forum that l thought might be good and it had an effects loop in it. Unfortunately I lost the post and can't remember who posted it. I'm gonna keep looking for it.

Thanks again for your input. Cheers!

[Tbone55]

I've only built 2 amps with fx loops - a Tubenit SoLow (7 watt push pull) and a 6V6 version of the Matchless Clubman which is another really good sounding amp that fits your power range of about 16 watts.

I was able to find a post on the forum about the Matchless Clubman. The build was based on the original Matchless Clubman 35w. The great thing is it includes an effects loop. I use pedals which is why I really want have an effects loop in the amp for my time based effects. The only information was a schematic.

This looks like a really interesting build and very different to what I already have. I think this amp will really do the trick. Would you be willing to help me out with your build info? Obviously there are going to be some differences in your build because you used 6V6's instead of EL34's.

Any help you can provide will be sincerely appreciated. Cheers!

[HotBluePlates]

Maybe I've misunderstood what HBP was referring to regarding the effects loop. ... Dougs Plexi 6V6 has a master volume control ...

Sorry, my mistake for not checking that circuit.

Doug's Plexi 6V6 does have a master volume control; I was thinking of "Marshall Plexi" amps which had the preamp circuit this Plexi-6V6 copies, and those amps are from the late-60s before Marshall added a master volume to any of their amps.

Master volume amps vary enormously in their preamp architecture, and resulting sound.  I'd recommend playing a bunch to decide which one sounds really good to you before pulling the trigger on which to buy/build.

... based on the original Matchless Clubman 35w. The great thing is it includes an effects loop. I use pedals which is why I really want have an effects loop in the amp for my time based effects. The only information was a schematic.

This looks like a really interesting build and very different to what I already have. I think this amp will really do the trick. ...

This is another one that doesn't make sense, even though it has an Effects Loop and a master volume.

The schematic shows the master volume comes after the loop.  When you turn Volume high and Master low to get dirt, the effects you put in the loop will also be distorted, because the distortion happens at the phase inverter, which is after the loop.

I used to own a Clubman 35 in the late-90s, but it was the version after the linked schematic & had an EF86 preamp tube rather than the 6SH7.  IMO, the master was "okay" but the amp sounded best with the Master full-up & the volume cranked to get the EL34s distorting.  The particular "cross-line master volume" doesn't sound that great in my experience, but I'm not a frequent master-volume amp user.

Just another example of how it may be wise to try the amp out if possible before committing to a design you haven't played before.  Because after that you could find out, "HBP was all wrong... this thing sounds great for my use!!"

[bmccowan]

Note: I wrote the below text while HBP was posting his reply. Glad to see he further explained. I agree with his advice about playing different amps. Of course, that may be difficult unless you have a lot of amp owning friends or live near a very patient guitar shop. Being addicted to building amps, I tend to build and then rebuild until I get a desirable result, or just get distracted and start something else Not very efficient, but the same can be said of most hobbies.

Sure, I'd be happy to help.
BTW, I am totally confused regarding the mix of info on the Plexi 6V6 and master volume/fx loop issue, and was hoping HotBluePlates would come back with clarification about his concerns. My Plexi 6V6 has the simple MV as the Sluckey/Doug schematics. For me, its utility is that the the amp has one jack feeding two channels. The two channels are mixed with the two Volume pots to achieve the desired tone. The MV allows the result to be modulated. I typically use a delay and a mild distortion pedal on the front end.
OK, back to the Clubman.
The original Clubman tube lineup was 12ax7 > 6SH7 > 12ax7 > 2xEL34
A second Matchless version switched out the 6SH7 for an EF86.
What I built was 6SL7 > 6SH7 > 6SL7 > 2x6v6
I just happen to like building with octal tube sockets, due to geezer age, arthritis, eyesight. Others have built 6v6 Clubman type amps with 12a_7s and an EF86 or 5879 in the preamp, and some have used a different type MV. I have some collected schematics that I will attach later after I round them up.
Basically the project is simply a cut and paste (cut and solder?) as described by HBP. The Clubman preamp pasted to a typical cathode biased 2x6V6 power section. Of course a PT and OT suitable for 6V6s.

[Tbone55]

Thanks HBP.

I hadn't looked at the Clubman schematic close enough to realize the master volume control was after the PI. I'm not very familiar with effects loops and their preferred position within the amp circuit but what you said about the effects being distorted does make sense. You don't want your time based effects to be affected by distortion. I should try the amp out before deciding on a build especially because of the effects loop. It would have been nice to build this as a 6V6. I've asked a member on the forum who built a 6V6 version of the Clubman if he would share his build with me. I'm curious to see if he left the master volume in the same place or changed it.

The Hoffman Plexi 6V6 seems like a pretty good choice to start with. I'd have to use a different chassis in order to fit a real tube effects loop, or even if I wanted to purchase a board like the one Mojotone sells. I still have to understand serial vs parallel effects loops for crying out loud.  Let the headaches begin.

Cheers!

[Willabe]

Your in Canada right?

You might want to look at Kevin O'Connor's kits. He's in Canada, his company is called London Power.

His kits are pricey, but if your in Canada it might be not as bad getting an FX loop kit from him, then from the US. No import taxes, etc.

Tube Amp Kits & Books, Tube Amps | London Power

And you should look at his amp books. TUT 1 has a whole chapter on FX loops. For anyone starting out getting books, I'd recommend TUT 1 and 2. You can look at the table of contents on his web store. I'd get these along with the Merlin books. The TUT books cover a very wide look at tube amps and FX loops, reverb, trem, switching,etc. 

TUT 1;
https://londonpower.com/tut-contents/

TUT 2;
https://londonpower.com/tut2-contents/

And TUT 3 has information on layout, wiring and grounding in it that I think is very good. Helped me a lot.

TUT 3;
https://londonpower.com/tut3-contents/

TUT 5 goes into depth about transformers and chokes.

TUT 5;
https://londonpower.com/tut5-contents/

TUT 5 and TUT 3 both have many full layout and full schematic drawings for amp builds in them.

Those 4 books along with the Merlin books gets you a good ways down the road on learning how to fix and build tube amps. 

[bmccowan]

I've asked a member on the forum who built a 6V6 version of the Clubman if he would share his build with me. I'm curious to see if he left the master volume in the same place or changed it.

That'd be me I guess. Happy to share - see reply #14. To your question - I wired the MV the same as Matchless has it. I have often thought to moving it and/or using a different type of MV. But, I also don't use MVs very much. Matchless amps are known for clean and loud, as HBP experienced. I have built two. The Club 6V6 and a Spitfire. I like their clean tones, although I needed to tame the treble in the Spitfire. If I add pedals it is usually a delay, set very mild, and an overdrive, also set on "I am a wimp."
I have Kevin O'connor's 1&2 - lots of good info there.
I also might suggest that you look at Ceriatone's range of amps. They have quite the selection of circuits with and without MV. What I do not like is that they publish layouts and no schematics

[Tbone55]

Note: I wrote the below text while HBP was posting his reply. Glad to see he further explained. I agree with his advice about playing different amps. Of course, that may be difficult unless you have a lot of amp owning friends or live near a very patient guitar shop. Being addicted to building amps, I tend to build and then rebuild until I get a desirable result, or just get distracted and start something else Not very efficient, but the same can be said of most hobbies.

Sure, I'd be happy to help.
BTW, I am totally confused regarding the mix of info on the Plexi 6V6 and master volume/fx loop issue, and was hoping HotBluePlates would come back with clarification about his concerns. My Plexi 6V6 has the simple MV as the Sluckey/Doug schematics. For me, its utility is that the the amp has one jack feeding two channels. The two channels are mixed with the two Volume pots to achieve the desired tone. The MV allows the result to be modulated. I typically use a delay and a mild distortion pedal on the front end.
OK, back to the Clubman.
The original Clubman tube lineup was 12ax7 > 6SH7 > 12ax7 > 2xEL34
A second Matchless version switched out the 6SH7 for an EF86.
What I built was 6SL7 > 6SH7 > 6SL7 > 2x6v6
I just happen to like building with octal tube sockets, due to geezer age, arthritis, eyesight. Others have built 6v6 Clubman type amps with 12a_7s and an EF86 or 5879 in the preamp, and some have used a different type MV. I have some collected schematics that I will attach later after I round them up.
Basically the project is simply a cut and paste (cut and solder?) as described by HBP. The Clubman preamp pasted to a typical cathode biased 2x6V6 power section. Of course a PT and OT suitable for 6V6s.

Thank You kindly for your detailed response. I've never tried a Clubman 35 but I can find out if one of my local music stores has one to try. I'm used to the regular 12AX7 pre-amp/inverter stages so the Clubman circuit is quite a departure for me.

I'm using reverb, delay and chorus or flanger effects which is why I'm looking to include an effects loop. They really don't sound very good when going through the pre-amp if I have any distortion. I have to turn the effects off when doing so. I've actually been using my amp modeler all the time because it allows me to separate the effects just like an fx loop. I want get back to using a tube amp but it has to an fx loop. I also want it to be an amp head to use with a cabinet.

I appreciate your help with this and am really looking forward to seeing what your schematics look like. It's probably gonna take me a bit of time
to sort out all the information as I'm as conversant in this stuff as most of the forum members are. 

Thanks again. Cheers!

[Tbone55]

Your in Canada right?

You might want to look at Kevin O'Connor's kits. He's in Canada, his company is called London Power.

His kits are pricey, but if your in Canada it might be not as bad getting an FX loop kit from him, then from the US. No import taxes, etc.

Tube Amp Kits & Books, Tube Amps | London Power

And you should look at his amp books. TUT 1 has a whole chapter on FX loops. For anyone starting out getting books, I'd recommend TUT 1 and 2. You can look at the table of contents on his web store. I'd get these along with the Merlin books. The TUT books cover a very wide look at tube amps and FX loops, reverb, trem, switching,etc. 

TUT 1;
https://londonpower.com/tut-contents/

TUT 2;
https://londonpower.com/tut2-contents/

And TUT 3 has information on layout, wiring and grounding in it that I think is very good. Helped me a lot.

TUT 3;
https://londonpower.com/tut3-contents/

TUT 5 goes into depth about transformers and chokes.

TUT 5;
https://londonpower.com/tut5-contents/

TUT 5 and TUT 3 both have many full layout and full schematic drawings for amp builds in them.

Those 4 books along with the Merlin books gets you a good ways down the road on learning how to fix and build tube amps.

Thanks very much Willabe for the  contacts in Canada. Everything here is pricey but then, what isn't these days. Thanks also for the book references. I actually have the Merlin Blencoe books on order and will definitely look at the other ones you suggested.

Your help is greatly appreciated. Cheers!

[bmccowan]

Tbone, Although, given the discussion, probably not your ideal amp, attached are some Clubman type schematics that I gathered a few years back, as well as the all Octal 6V6 version I cobbled together. The others represent Matchless versions and versions from other hobbyists. Some are sch files. I assume you have that program - if not, highly recommended.
Hit max - If there are others I will repost.

[bmccowan]

A couple more

[Tbone55]

Bmccowan thanks so much for the schematics. I won't be able to open the .sch files. What program do I need? When referring to PPIMV am I correct in assuming it means Pre Phase Inverter Master Volume?

Thanks Again. Cheers!

[bmccowan]

ExpressSCH - there are links to it right here on the Forum and Doug has lots of user tips. I really like using it. I find that I rarely need to start from scratch - just open a similar schematic and modify it.
PPIMV typically means Post Phase Inverter MV - as in the schematic that is tagged Tubenit.

[Tbone55]

Thanks Kindly bmccowan.

I'll look up the program. Sounds like it'll be a big help. With respect to the location of the MV in the fx loop, it can be either before or after the PI. If it's after the PI, it seems it'll distort the time based effects in the loop.  It seems preferable that the MV be placed prior to the PI. I've got to read over the stuff about fx loops from tubenit some more. Would this build be possible in a 16" chassis?

Thanks again.

[bmccowan]

Tubenit is great - very helpful and I like his approach. And he likely can provide very good guidance on where to place fx loops in the circuit and what circuits work well with what. As I get older (70+) I tend toward clean, sweet, tones, so I need to sell or give away some of my pedals. I built a brownface Princeton 6G2 a while back and I am loving that amp straight in from a Tele, Strat, or a P90 ES-150. It happens with age. At least I am not yet listening to the Oakridge Boys

[tubenit]

With respect to the location of the MV in the fx loop, it can be either before or after the PI. If it's after the PI, it seems it'll distort the time based effects in the loop.  It seems preferable that the MV be placed prior to the PI.

It has not been my experience to hear any distortion of delay or reverb in an FX loop with a post phase invertor master volume.  The PPIMV sounds fine to me with both passive and active FX loops just prior to the phase invertor.


Remember an active FX loop just prior to the phase invertor has an FX send and FX return pot which in some ways function as a pre phase invertor master volume. 


I'm super happy with the tone of my amps that have a "psuedo" active FX loop with a PPIMV.


Friends I have  that have played thru the amps have been very complimentary of the tone of these two amps. I have one friend who has 4 vintage Fender amps and he asked me to build him an amp similar to the D-763 & he has commented that it has better tone than his vintage Fenders for the volume he plays at in his home and at open mics.


With respect, Tubenit

[Tbone55]

Tubenit is great - very helpful and I like his approach. And he likely can provide very good guidance on where to place fx loops in the circuit and what circuits work well with what. As I get older (70+) I tend toward clean, sweet, tones, so I need to sell or give away some of my pedals. I built a brownface Princeton 6G2 a while back and I am loving that amp straight in from a Tele, Strat, or a P90 ES-150. It happens with age. At least I am not yet listening to the Oakridge Boys

🤣🤣🤣 well I'm not much younger than you so we've got that in common. I do like some grit in my tone but not anything really heavy. Still mostly classic rock and such. It's funny, but what we used to think of as being a lot of distortion when we were growing up with bands like Zeppelin and AC/DC aren't really that distorted after all. One of the biggest mistakes a lot of players make is playing their stuff with too much distortion.

Sincerely appreciate your input and help with what is likely going to be a long term project. Winter's coming and I need to keep busy. 🤗

[Tbone55]

Hello tubenit. Thanks kindly for your response and input.

The fx loop is a whole new world for me and I've got plenty to learn about it so any help and advice you can provide is sincerely appreciated.

Thanks for providing the two schematics. There's really a lot I don't know about fx loops so when I hear active, passive, serial, parallel I'm out of my depth. I'm waiting for books so I can read up about them more. I am curious why you call yours a "pseudo" effects loop.

Cheers!

[Tbone55]

Came across an interesting build. The plans are available for free. There's also an FX loop circuit available at a cost. Here's a link to the site.

https://www.elamscafeboutique.com/s-projects-side-by-side

The builder has a Youtube video also where he goes through the build and his FX loop as well as sound demonstrations.

Cheers!

[bmccowan]

That does look pretty nice. He does a lot of fabricating but shortcuts could involve buying the Mojotone chassis and having Doug make up the turret board for you.

[tubenit]

I am curious why you call yours a "pseudo" effects loop.

   

I'm referring to it as a psuedo "active" effects loop.

If you look here  tube effects loop on board (el34world.com)  you will find a considerable amount of information about on board effects loops.  Typically they have a "send" gain stage that looks similar in some fashion to a cathode follower.

I'm simply using a cathode follower in the 2nd gain stage of the amp along with the CF tone stack in that regard. That's why I'm using the term psuedo active FX loop.

I've used FX loops similar to the Dumblator and this psuedo active FX loop idea using a  mosfet CF has worked just as well with my delay and reverb time based effects.

With respect, Tubenit.

[Tbone55]

That does look pretty nice. He does a lot of fabricating but shortcuts could involve buying the Mojotone chassis and having Doug make up the turret board for you.

I thought it was too. Buying the Mojotone chassis is definitely a shortcut. I don't know if I'm up to fabricating a chassis. That to me is the hardest part of building an amp. Doug could easily make up the turret board for me as well. Could he do it from the plan or would I have to draw it up in Doug's program? I really like the idea of being able to go from clean to dirty with a flip of a switch. It'd be even better to be able to do it with a footswitch  .

His FX Loop board is a big plus to me, especially since he designed it to work with the amp. I don't know much about it design wise but it's buffered and is a parallel loop. Think I'll have to investigate some of the other FX loops available before deciding. Is the reason for having the separate FX Loop volume and gain because not all pedals, I think older pedals, don't have have it onboard? All of the pedals I have have separate level and gain controls on them. Does this mean you don't need an actual board but can tap into the circuit and only have to put send and return jacks on the chassis? It's probably not that simple I'm guessing.

Neither Doug's Plexi 6V6 or elamsboutique Punch Plate use anything but 12AX7's in the pre-amp section. I've kind of been toying with using a 5879 in either V1 or V2. How much of a difference would this make gain wise instead of using a 12AX7? Is the 5879 more suited for clean? I think it's the Clubman 35 that uses it. Will have to check my local music store and see what they have.

Thanks for taking the time to have a look at the site and provide some feedback. I sincerely appreciate it. Cheers!

[Tbone55]

I am curious why you call yours a "pseudo" effects loop.

   

I'm referring to it as a psuedo "active" effects loop.

If you look here  tube effects loop on board (el34world.com)  you will find a considerable amount of information about on board effects loops.  Typically they have a "send" gain stage that looks similar in some fashion to a cathode follower.

I'm simply using a cathode follower in the 2nd gain stage of the amp along with the CF tone stack in that regard. That's why I'm using the term psuedo active FX loop.

I've used FX loops similar to the Dumblator and this psuedo active FX loop idea using a  mosfet CF has worked just as well with my delay and reverb time based effects.

With respect, Tubenit.

Thanks Kindly Tubenit.

As I said, I know very little about on board FX Loops and have only been reading up about the types of FX Loops ( serial, parallel). I've also been looking at a few different schematics to understand the placement of the send and return signals. I may have been reading the very link you've mentioned but I think it was going over my head a bit so I'll go back and read it again. From what I've seen you've really done a lot of work with this area.

Cheers!

[AlNewman]

That does look pretty nice. He does a lot of fabricating but shortcuts could involve buying the Mojotone chassis and having Doug make up the turret board for you.

Neither Doug's Plexi 6V6 or elamsboutique Punch Plate use anything but 12AX7's in the pre-amp section. I've kind of been toying with using a 5879 in either V1 or V2.

Here's a good resource that can tell you everything you've ever wanted to know about tubes.
https://frank.pocnet.net/

[HotBluePlates]

... 5879 ... Will have to check my local music store and see what they have.

AFAIK, the 5879 only exists in old production tubes (generally American-made).  However, they might be as-cheap or cheaper than modern 12AX7s.

[bmccowan]

Neither Doug's Plexi 6V6 or elamsboutique Punch Plate use anything but 12AX7's in the pre-amp section. I've kind of been toying with using a 5879 in either V1 or V2. How much of a difference would this make gain wise instead of using a 12AX7? Is the 5879 more suited for clean? I think it's the Clubman 35 that uses it. Will have to check my local music store and see what they have.

As HBP says, there are no current production 5879. They were extensively used in military communication and also in tape recorders, etc. as well as some guitar amps. So far they are not scarce NOS.
As far as your gain question goes - there is no simple answer. Both dual triodes (12AX7's) and pentodes (5879) can be setup for a wide range of gain, from mild to wild. The difference is in the tone - which can also vary greatly. Tubenit had a good description of the tone. It also varies whether the 5879 is used in the first position or in the second position driven by a dual triode - similar to the Clubman which uses the similar ef86. Many many amps from the 40s and 50s used 6SJ7s in the preamp. Its an octal tube that is  similar to the 5879 in tone and application. So it comes down to listening to amps and player opinions. As a player, builder, repairer, collector, I am unable to say I prefer one preamp type over the over. It depends on my mood, the music I am playing, etc. My suggestion - find an amp tone you like and build something similar.
12ax7s have some practical advantages: the local store availability, the flexibility of being able to swap in 12ay7, 12av7, 12at7, 12au7, 5751 in the same socket for a change in gain and tone.
I think you may be heading toward an amp building addiction - if so, you can have your cake and eat it too

[Tbone55]

My sincerest thanks to AINewman, HBP, bmccowan, sluckey and tubenit for your responses. Your info and perspectives are truly appreciated as I try to navigate my new found rabbit hole of building this amp. Great resouces have been provided and it's up to me to review them, understand them, and determine the direction I want to go in.

I do have a question about the program that lets you create your own schematics, Expresssch. I was going to download it but it asks for permission to make changes to your device and that kind of concerned me. Obviously there are many of you using this program already but I wanted ask before I download it. 

Thanks again everyone. 🤗

[bmccowan]

I do have a question about the program that lets you create your own schematics, Expresssch. I was going to download it but it asks for permission to make changes to your device and that kind of concerned me. Obviously there are many of you using this program already but I wanted ask before I download it.

Hmm, maybe that's what happened to my Fidelity account?
If you follow Doug's instructions here https://el34world.com/Forum/index.php?topic=590.0 you should be fine.

[Tbone55]

I've downloaded the expresspcb program from Doug's link and have been going through his post of tips. Haven't tried using the program yet as I've started reading through some of the books I ordered. I've got the two Merlin Blencoe books and the ultimate tone book by Kevin O'Connor I want to go through before deciding on the direction I want to take with this build. There's a lot I don't know. At some point I will come back with some ideas.

Thanks Everyone. Cheers!