Recommend Black Face Deluxe Reverb Kit

[Diablo]

I want to build a BF Deluxe Reverb kit. I'd prefer just the head, but may consider a combo. I want everything in the kit to be first class because I only want to do this once. I'd like to hear recommendations from the folks with experience, even some manufacturers if possible. I've been looking at Allen amps and Weber so far.

[Chris - CMW amps]

If you truly want the best you need different suppliers for this project; one for the cabinet, one for the transformers, one for the speaker(s), etc., etc.

It's all very subjective but I did do it a couple of times for customers;
- cab/chassis/eyeletboards/etc. from Mojotone
- Celestion Heritage H30 speaker(s)
- Mercury Magnetics transformers and choke
- Accutronics reverb-tank
- TAD ("audiocap") e-caps for the powersupply and cathodes
- couple of Sprague e-caps
- Mallory and/or TAD ("mustards") coupling-caps
- Alpha and/or Weber pots (depending on the taper)

Hope this does help a bit.

[Bruce / Mission Amps]

I'd go with a dead stock MOJO kit. The parts included are all high quality, top notch!
I think it is superior to all others in just about all respects and uses Heyboer transformers.

No real serious changes at all except:
use five 22uF-500v TAD main B+ filter caps (I think they are actually SINO import caps, but excellent),
Use a real NOS 5U4GB rectifier tube,
and, mess with the first stage preamp tubes if you can get some NOS ones.
I've built two myself, worked on and tweaked three others for home brew builders and have been very happy with the results when used with a G12H30 speaker.

[Mandopicker]

The Mojo Deluxe Reverb is a great kit to build.

As was suggested, all parts are top notch. I did, on the other hand, beef up the filter caps even more as well as subbed silver mica for ceramic disks when possible.

My kit came with the GZ34 (All JJ tubes)

Perhaps later the speaker can be upgraded, but I don't think that the entire kit suffers as a result if the supplied Jenson C12.

[Diablo]

I did a little googling on mojokits, and folks claim there are little to no instructions with the kits. That worries me. I'd like a kit to have good instructions and support behind it if I need it. On the other hand, Allen kits are claimed to have good instructions and support. So, can anyone compare the components and schematic used in Allen Accomplice (BF Deluxe Reverb topology) to the Mojo, and how they sound?

[Mandopicker]

My Mojo came with a very large printout (11x17) of the original schematic and Layout making it real easy to follow.

As far as additional instructions...you certainly have a wealth of knowledge available from folks in this forum.

Pretty sure that whatever you will come across during the process has been seen a thousand times before by others and as a result, ideas and solutions abound.

Go with the kit that offers the best parts relative to what you would like to spend, and your comfort zone with a soldering iron.

You'll be fine.

Just my 2 cents.

[TheTinMan]

Check out the kit from Marsh Amplification. Don't know about what instructions you might get, but Marsh sells Mojo cabs, chassis, etc. for less than Mojo. Also, you can get a nice Weber speaker too. Excellent customer service for getting parts.

That said, Dave Allen's kits are top notch quality and his support is supposed to be excellent (no direct experience w/ Allen's kits).

Hope this helps,

Chip

[cminor9]

I am still a bit of a noob at this whole amp building game, but I have read the opinions of some experts who believe "parts is parts". When you think about it from one aspect, Fender even in the 50s and 60s was a business which needed to be profitable. You don't get profitable by using the costliest parts you can find. You find the best value parts (and not necessarily the *cheapest*) that will work and make em work. Sure, Leo Fender was obviously after a certain tone. But he was a businessman.

http://www.tone-lizard.com/Electronic_Parts.htm is where I found an interesting article discussing this. Do you think that using the finest transformers money can buy or those expensive capacitors really makes a difference? Knowing what I know about marketing and gullibility I am really inclined to think it is snake oil. All you amp experts out there, what is your take on this notion? Anyone with any *real* experience out there building amps from cheaper parts vs expensive parts?

Please note that I am not talking about using the cheapest parts money can buy. I am talking about using say, a decent but maybe not top shelf Hammond transformer as opposed to an overpriced MM. Good old orange drops as opposed to $20-a-pop coupling caps.

Anyone?

[geoffbob]

Hi: <first post and going out on an opinion limb already>

cminor9 makes a good point. This whole business of tone is highly subjective. I have some experience with blind test results in ABing different components and generally agree. This is also a classic can o' worms topic :) so lots of fun to discuss. Without a blind AB test you never know. Ever read a review of an expecnsivve piece of equipment where the new owner admitted it is crap and they are stupid for buying it. More than likely they say "this changed my life", then 8 months later they are reviewing the next one.

My opinion is similarly constructed components will be electrically equivalent - a .1 uF bypass cap is a .1 uF bypass cap. Caps of similar construction will generally sound the same, but comparing ceramic disks to poly caps will show up differences due to the physical construction and materials used. Similarly with transformers... I have swapped out different output transformers and observed different tonal charactersitics, I expect due to the metal type and mass in the plates, not the wiring specs - which are the same.

I follow this rule with kit builds: use great speakers, use good OTs (Heyboer have always worked for me here - MMs are expensive for similar results), use good controls (pots, switches, jacks) - anything that gets hands on it needs to be robust, then build it like you care how it turns out. I have never had bad results following this model and people love my amps.

Cheers, ..Geoff

[TheTinMan]

Geoff & cminor make sense IMHO. If you get decent quality components, you should be fine. The speaker, cab & OT make the biggest difference as far as I can tell.

Take cables for example. Can I hear the difference between a private label cheapie from the local music store and a decent Planet Waves/Monster/George L/decent DIY? Sure can! Can I hear the difference between the Planet Waves - Monster - George L - decent DIY? barely if at all and a tweak of my guitar's tone knob makes a much bigger change in tone. It's more a matter of taste if anything IME.

But Diablo wants a good BF Deluxe kit. He doesn't seem to want to source all of his own parts and I don't blame him. Even trying to minimize the number of sources, shipping ate up over 10% of the cost of my last build. Either Allen or Marsh would be good alternatives for him, providing all of the necessary parts with better than adequate quality.

Chip

[cminor9]

Oh no, you mentioned cables! Now you've opened the box :)

With cables, I cannot tell a whole lot of difference. To me, what makes the most difference is the length of the cable. I use a 12' cable instead of a 25' or 30' cable.

I am of the belief that if you can't measure it it doesn't exist. Carbon comp resistors provide a measurable effect (distortion and non-linearity, which can be good). You can theoretically measure impedance over a long cable. I don't think you can measure any differences between a Monster Cable and a cheapie. Sure, maybe the lighter cable would melt of you ran 15 amps (amperes, not guitar amps) through it. Think of how small the signal is from a guitar pickup. Why on earth would anyone think you need a 12ga wire for that?

I get a kick out of those audiophile websites that tout the benefits of $1k/foot oxygen-free virgin copper cable or $60 foil-in-oil coupling capacitors. I also get a kick out of those mojo vitamin-T caps for the same reason. Until someone can *measure* a difference between the various caps, count me out.

I am surprised nobody has disagreed with the original point yet.

[Diablo]

I made my decision and ordered a Mojo kit from Marsh Amps with a Weber 12A125 Alnico speaker. I'll be reporting back here for more advice, I'm sure. I've got quite a few good vintage tubes to try out in the amp, and will sub in a 5U4GB rectifier tube as per Bruce's suggestion. Thanks for everyone's help on this one...:)

[TheTinMan]

Diablo - I know that you wanted one-stop shopping, but if that kit uses "tag board" with eyelets you might want to consider getting a pre-made board made out of Garrolite from Watts Tube Audio (turretboards.com). You can get an AB763 board made with either eyelets or turrets. I've had really good experience with them.

You did say you wanted the build to be "first class" and tagboard is not IMHO.

Chip

[MWJB]

C Minor wrote "With cables, I cannot tell a whole lot of difference. To me, what makes the most difference is the length of the cable. I use a 12' cable instead of a 25' or 30' cable. " There is a huge difference between the sound of differing brands & constructions of cables. A few years ago I tested a whole bunch all at 10'. I have made 25' cables that still sound better than average (performance-wise) cables of 10'.

What difference do you want to measure, like capactance per foot, (most manufacturers have figures, 25pf/ft is good going, I think Lava have a 15pf/ft cable!). What do you do when 2 cables with the same spec sound vastly different (it happens). It's easier to measure with a good meter than the difference between carbon comp/film resistors. How exactly do you measure your carbon comp resistors, at home, to show the tone difference?

You don't need to spend vast sums on decent cable, many really good sounding cables are mid priced (Klotz La Grange, Planet Waves, Sommer Session II). Some budget cables are surprisingly good (Proel) and colour the sound in a pleasant manner, some $10+/foot cables are pretty good but not astounding...you have to suck 'em and see. After breaking down as many aspects as I could, there was not a definite trend, that I could spot, that favoured one method of construction (thickness of conductor, type of dialetric, spiral vs. braided sheild) over another. So, yes there is a degree of snake oil out there, everyone's got a USP to shout about that seperates their product from the herd...it's just they don't all work when it comes to the execution (like all products in life).

How do you measure the performance of a band/musician/CD/amp tone...? You listen to it.

"I am surprised nobody has disagreed with the original point yet." Check out "new" pricess for amps from the 50's & 60's, Fenders WERE relatively expensive. They did spend more on parts than a lot of other manufacturers. Check out the specs on the blonde Vibrasonic. A bunch of the early 60's 40W amps were built with 100W power transformers.

I suspect that you're playing Devil's Advocate to degree here.

[cminor9]

"I suspect that you're playing Devil's Advocate to degree here. "

Heh, maybe a bit. I do like to question conventional wisdom. Just trying to stimulate a discussion. This is something that I have been thinking about as I start sourcing my next build. Do I need to spend top dollar on speakers? Well, yeah a good speaker definitely. But top dollar for capacitors, MM transformers, etc? I don't know, and I am leaning away from it. But before I plunk down my hard earned, I'd like to discuss with *someone* who knows something AND isn't trying to sell me anything.

"Check out "new" pricess for amps from the 50's & 60's, Fenders WERE relatively expensive."
Well sure, they were certainly more expensive than other amps. But they weren't as expensive as today's boutique amps. I'd be interested in finding some inflation calculator that goes back to 1955, because I doubt the Fender deluxe cost the equivalent of what it goes for today as a reissue. My point was that Leo Fender still had a business to run. Good businesses don't lose money, they make money. The way to make money is to cut costs. The way to cut costs is look for values. Value doesn't mean you go el cheapo. It means you get the best products you can so long as it doesn't negatively affect your profit margin or your price point. I seriously doubt Leo Fender would use MM transformers today unless they cut him a serious break.

[TheTinMan]

cminor - it sounds like you've already made up your mind to a certain extent, but there ARE real, audible differences between cheap and decent quality components.

I don't especially care about measuring with anything other than my ears, but I can hear a big difference between cheap cables and decent cables. Frankly, I wasn't expecting to when I did A/B/C/D tests.

Speakers - everything else could be great and still sound terrible with a bad speaker or even the wrong speaker for a given application. Take a stock Blues Jr. as a prime example.

Cabinet - material, construction, open vs. closed, dimensions, baffle board mounting ALL make differences you can hear. You could use the best of everything else, put it in an MDF cube, and it will sound terrible.

Tubes - yes, you can hear differences but that doesn't mean you must have $250 Telefunkens. Cycle a handful of current production 12AX7s through a Tweed Champ and you'll find the ones you like (and don't like).

Output transformer - it can be "too good" as well as "cheap". I've got a 5F2-A build with a high quality OT from Dave Allen that's going to get pulled and replaced by the smaller, cheaper one that came with the "kit". Bigger & better makes too much bass and somehow the distortion isn't as sweet. IME output transformers may have the most mojo of any component. (Allen's OT will go in another build it's better suited to.)

Power transformer - 25 volts plus or minus on B+ can be heard in many amps. Way too big or way too small would be bad, but is there really value added from boutique here? Don't know. BTW no one should pay full retail for Mercury Magnetics. I like their product but sure won't pay the 1 unit prices!

You don't want anything mechanical to fail - pots, tube sockets, jacks, switchs - just aren't worth skimping on.

Caps & resistors - search the web and read on...

And then there's shipping costs. IMHO you're much better off if you can find maybe three suppliers you can count on for acceptable quality and good customer service to get everything. Finding the lowest price for every part will drive you crazy and cost you a fortune in shipping. Between Hoffman, AES, Mojo (Marsh actually) and Mouser, I can get virtually everything I need.

Hope this helps,

Chip

[cminor9]

TheTinMan, yeah, that's all pretty much how I feel about all the various parts. Some need to be good, some are just silly to overpay for. Speakers, cab design and materials, and tubes clearly need to be good and the right choice for whatever sound you are after ;)

The original post mentioned MM transformers. I was just wondering (aloud) if anyone really found a way to justify overpriced transformers, cables, and caps. Sounds like a few folks think cables matter, but nobody has really spoken up on overpriced transformers or touted the virtues of those ridiculously overpriced "audiophile" caps. I guess that just kind of confirms what I already thought.

[MWJB]

MM transformers are not that expensive, they are overpriced for what they are though. Good quality fender style replacements like Hyboer & Lenco will do the job plenty good (standard caveat with all these aspects - unless there is something specific you personally are after).

Foil & oil caps - lack character, I've fitted them to amps & then taken them back out at the owners request - how much difference do they make though? Less difference than you'll hear from one cable to another! They were never fitted as stock to any classic production amp. Some claim to prefer the less coloured tone, others just read them off in a list of components as if they were reading qualifications from their resume, as if it makes them a better player! If you use regular priced OD or Mallory caps and your amp doesn't sound good, it's because of something you have done in the build NOT the caps.

I even use cheaper Euro metallised poly caps in my own amps & repairs where the customer isn't brand concious - sometimes you have to fit parts that give a customer peace of mind. Metal film resistors & square poly coupling caps in vintage rebuild? The customer won't thank you at resale time when the amp is picked apart on Ebay!

Speakers? Well, the one you like the sound of best is the one to use, price is the secondary consideration. Trouble is few get the opportunity to A/B test speakers in the same amp withiout having to stump up their hard earned first. I've spent $200+ on a speaker and found it money well spent, conversely I've spent $75 and felt I was robbed.

Central to all this is the importance of ear testing, listening is not a passive experience, you may not hear certain things until someone more experienced points them out.. then you can't get away from it & design it out of new builds etc. The more ear testing you do the better you get...memory for sound is generally very poor (unlike smell for instance, ever walked into a room and been mentally transported 20yrs back to school because of the smell of the floor polish etc?). At first, by the time you've heated up an iron removed the old part & installed the new, you often can't remember what the original part sounded like...eventually you get better at it - if there is a charcteristic that you don't like/want more of, you will recognise it after modding. Being able to rig up instant A/B tests is a good thing to do when starting out.

[Diablo]

OK, let's get back to building the Deluxe Reverb kit. My Mojo kit is on the way, and I did an inventory of rectifier tubes. I have:
5V4G - coke bottle
5V4GA
5U4G - coke bottle
5U4GB
5Y3G - coke bottle
5Y3GT

I understand that 5V4 is higher voltage than 5U4 which is higher voltage than 5Y3. Will they all work OK in the kit with a rebias?

For power tubes, I have:
6V6G - coke bottle
6V6GT
I assume these will work OK with a rebias?

I also have some very old 6L6 coke bottles - I assume those won't work because they'll draw too much power?

Opinions please.

[Bruce / Mission Amps]

Diablo - I know that you wanted one-stop shopping, but if that kit uses "tag board" with eyelets you might want to consider getting a pre-made board made out of Garrolite from Watts Tube Audio (turretboards.com). You can get an AB763 board made with either eyelets or turrets. I've had really good experience with them.

You did say you wanted the build to be "first class" and tagboard is not IMHO.

ChipI agree with much of your other statements but I'm glad you said IMHO this last time because like mine, that's all that is, your opinion.
But I think you are 100% wrong about eyelet boards... and I have over 1,250 amps and kits out in the field to back that statement up.
Eyelet boards are wonderful.
When done properly, first class and much easier for novice builders to work with because it is very easy to remove and replace parts on them, unlike Turret boards, which IMHO, are a royal pain in the ass to work with when it comes to R and R'ing parts that have been installed on turrets the way most people try to do.
Now it is true that MOJO makes their own eyelet boards, as I do, but their downfall is, as many others, that there are some areas that require three, four or more wires, resistor or capacitor leads to be inserted in an 1/8" dia eyelet, who's actual inside dimension is not even 1/8"... and that makes it hard.
In those special cases I use larger brass eyelets in those spots so a builder doesn't suffer that difficulty!
A simple remedy, where it appears I am the only one who does take these things into consideration.

[Bruce / Mission Amps]

OK, let's get back to building the Deluxe Reverb kit. My Mojo kit is on the way, and I did an inventory of rectifier tubes. I have:
5V4G - coke bottle
5V4GA
5U4G - coke bottle
5U4GB
5Y3G - coke bottle
5Y3GT

I understand that 5V4 is higher voltage than 5U4 which is higher voltage than 5Y3. Will they all work OK in the kit with a rebias?

For power tubes, I have:
6V6G - coke bottle
6V6GT
I assume these will work OK with a rebias?

I also have some very old 6L6 coke bottles - I assume those won't work because they'll draw too much power?

Opinions please.Personally I would build the amp first and use all the cheap tubes that came with it to get it up and running correctly!!
I would probably favor the 5U4GB in place of the others mentioned and if you have NOS 6V6s, I'd use those even though the 6V6EHs are actually quite good.
You normally would not ever use a 5Y3GT rectifier in a Deluxe Reverb.
The black face ones, with their 110ma PTs and lower B+, wound for 115vac to 120vac, would be using a GZ34/5AR4
The 5V4 is not a higher voltage tube then a 5U4GB. It is a lower current handling tube (125 to 150ma max) and it has a different impedance then the others so depending on the current load through your rectifier, the actual B+ voltage will vary greatly depending on what rectifier you use.
This would be OK in a DR... but I'd still consider the 5U4GB, unless MOJO says their PT is wound with period corrected secondaries and then you should use a GZ34/5AR4....
The 5U4GB is rated at an incredible 275ma to 500ma. Two of these in parallel could run a 100 watt amp all day long.
So even though it has a high impedance and will drop some voltage across itself when used, it can handle a boat load of B+ current.
The 6L6 coke bottles should work fine if you set the idle current of each so they are not running more then around 12-15 watts each, though the DR OT is wound for an impedance that better suits a pair of class AB1, fixed bias 6V6s.

[Diablo]

Thanks Bruce. Your advice about using the new cheap tubes makes sense for firing up a new amp build.

[TheTinMan]

I agree with much of your other statements but I'm glad you said IMHO this last time because like mine, that's all that is, your opinion.
But I think you are 100% wrong about eyelet boards... and I have over 1,250 amps and kits out in the field to back that statement up.
Eyelet boards are wonderful.
When done properly, first class and much easier for novice builders to work with because it is very easy to remove and replace parts on them, unlike Turret boards, which IMHO, are a royal pain in the ass to work with when it comes to R and R'ing parts that have been installed on turrets the way most people try to do.
Now it is true that MOJO makes their own eyelet boards, as I do, but their downfall is, as many others, that there are some areas that require three, four or more wires, resistor or capacitor leads to be inserted in an 1/8" dia eyelet, who's actual inside dimension is not even 1/8"... and that makes it hard.
In those special cases I use larger brass eyelets in those spots so a builder doesn't suffer that difficulty!
A simple remedy, where it appears I am the only one who does take these things into consideration.

Bruce - First off, your opinions should carry more weight than my "facts".

Obviously I wasn't clear in my earlier post. My point was that I prefer a solid G-10 or GP-03 board to tagboard, not turrets vs. eyelets. More robust construction without humidity problems. (Living in Virginia makes one worry about humidity ;)) Even so, Leo Fender made a crapload more amps using tagboard than all of us here put together will ever build!

Turrets vs. eyelets is purely personal preference, and I didn't even state mine. I did mention that turretboards.com makes boards with either turrets or eyelets despite the name.

Frankly, I'm coming to the conclusion that turrets require more planning in advance about what will be connected where. Sometimes it's better to have what seems like an "extra" turret (or two) just to avoid tying too many things to one point. Even so, you're right about it being hard sometimes to replace parts and tweak things with turret construction.

Your suggestion about using larger eyelets for potential problem spots is great!

Sorry I hit an obvious "hot button" for you.

Cheers,

Chip

[Diablo]

I'll have a good look at the board material that comes with the Mojo kit. I have G10 available at work, and can order up some eyelets or turrets to do a prettier job. I was thinking it should be pretty simple to use the board they supply as a template to make my duplicate board from G10.

I was even thinking about making up a duplicate chassis - we have a new water jet machine at work, press brake, and lots of galvanized steel sheet.

[Mandopicker]

Not sure if it is necessary to spend a lot of extra time making a new board for the Mojo kit. I found the existing board design and material to be as good as any.

* Though I have neglected the center screw to hold the board down. This is because I wanted to position it such that it does not effect the way the filtercap board sits under the dog house. My original fenders just used a sheet metal screw which effects how neatly the board sits on the chassis and I wanted to avoid this.

As a result, I have elivated the filtercaps to allow for the correct screw, but have been just too lazy to take the amp apart again to do it. The amp just sounds so good right now. When I run out of projects, I'll add the center board attachment screw.

Anyway...that's what is great about building an amp from a kit...like Burger King...you can have it your way.

Have fun!

[Bruce / Mission Amps]

Bruce - First off, your opinions should carry more weight than my "facts".

Sorry I hit an obvious "hot button" for you.

Cheers,

Chip
Ya know, I re read my comments and it did sound like I was pissy for some reason and I didn't mean it that way.
I must have misunderstood your comment but, you used the word eyelets with tag board so I assumed you meant standard rivlets and eyelet boards, as seen in thousands and thousands of amps made by Fender, Marshall and zillions of others over the years.
However, by using the term "tag board" did you mean just the insulation board itself, or the boards with riveted on loops, like old VOX amps had?
Those loops things are OK, but I find that the old ones break easily if mis-handled with the soldering iron, lead pull offs or yanking parts off with needle nose pliers.

In my mind, tag board is kind of a carboardy, fiber thing and insulation board, like the G10 or FR4, both being a totally different thing.
I use the G10 and FR4 black stuff, cut and bored with a big $$ Laser machine for my boards while MOJO and WeberVST is/was (maybe still do) use a vulcanized carboardy thing, probably shear cut, and I think they're machine punched.
I think both boards are fine for the low voltage stuff we do with guitar amps.

[Diablo]

The kit has arrived. First thing I want to do is to drill the cabinet for the chassis strap holes. I was thinking of laying the chassis on top of the cabinet and using the chassis as a drill guide. Is there a clever way to locate the chassis on top of the cabinet for this step? Or, does anyone have the dimensions of the setback from the front slant of the cabinet to the chassis faceplate?

[MWJB]

Turn the chassis upside down, put it on top of the cab. Use a straight edge against the baffle board edge (where the beading is, behind the grill cloth) & line the leading edge of the slant so that it lines up with the edge of the baffle board (should be flush when all is tight), then make sure chassis is centred with regards to width of cab. Use the chassis holes to make some transfer marks on the top of the cab for your mounting holes.

[TD_Madden]

I STILL don't get why that cab isn't predrilled..it's THEIR kit, after all!

[TheTinMan]

I STILL don't get why that cab isn't predrilled..it's THEIR kit, after all!

I agree that it would be nice in a perfect world...
Some people buy the cab to use with a different chassis and the cab is made in a factory. Stocking two sets of cabs, one with holes and one without, would be a pain. Having some guy/girl in the warehouse drilling holes in cabs just before packaging them would cost more and risk quality control.

Chip

[MWJB]

Diablo, next job is to make sure your fibreboards match each other & the chassis holes. You don't want to have loaded up the board to find that nothing lines up.

[TD_Madden]

I agree that it would be nice in a perfect world...
Some people buy the cab to use with a different chassis and the cab is made in a factory. Stocking two sets of cabs, one with holes and one without, would be a pain. Having some guy/girl in the warehouse drilling holes in cabs just before packaging them would cost more and risk quality control.

Chip

I can see that....I suppose only the higher-quality kit-makers (like Mission) take the time to do that....

[Diablo]

Diablo, next job is to make sure your fibreboards match each other & the chassis holes. You don't want to have loaded up the board to find that nothing lines up.


OK, I've got 6 fibreboards, for each pair there is one with eyelets and one with no eyelets and no holes. The instructions don't say what to do with the blank fibreboards. I assume the blanks go under the loaded boards and insulate it from the chassis?

[TheTinMan]

IIRC you wire up the board(s) with the eyelets, including all of the under-board and off-board wires. Then you use the blank board as insulation between the chassis and the eyelet board with components & wires.

Hope this helps,

Chip

[Diablo]

OK, thanks for verifying what the blank boards are for. I drilled the cabinet last night for the chassis straps. I took off the handle first so the chassis would sit flat on the top of the cabinet when drilling. I also figured the job would be easier if I didn't flip the chassis over because the bottom holes in the chassis are smaller diameter than the top ones - you get a more precise drill location into the cabinet using the smaller bottom holes. When I mounted the chassis I found out that the cabinet hole locations aren't super critical because you can push the chassis forward and back, left and right as you tighten the bolts to center the chassis.

[Diablo]

I stuffed and soldered the main circuit board. I want to solder the hook up wires to the board, but the kit only includes 30 ft of yellow (22 gage solid), 10 ft of green (18 gage solid), 3 ft of black (18 gage stranded), and 3 ft of white (18 gage stranded). The layout shows red, white, blue, yellow, black, green, brown. Oh, and Marsh Amps is closed for vacation or I'd be bugging them right now. I don't understand why they don't include the proper colored wires. I checked their website and they do sell all those colored wires, but for very high prices ($50/spool...wow!).

I guess the only thing to do is to order some wire from antique electronic supply, or if anyone has any better ideas let me know.

[TheTinMan]

Diablo - you can order true vintage style cloth covered wire from Hoffman Amps (http://www.hoffmanamps.com) by the foot. Figure out if you need any nuts, bolts, washers, shielded cable, etc. while you're at it. Doug Hoffman is amazingly fast at turning orders around and his shipping costs are very reasonable IMHO.

BTW the cloth covered wire AES sells is "modern wire" with a cloth covering... not my first choice but YMMV.

Chip

[Diablo]

Thanks Chip for the link to Hoffman. I was a little quick on the trigger and ordered the wire from AES.

Reading ahead in the instructions, they mention shielded wire to connect the input jacks and volume control wiper to the preamp tube grids to reduce noise. There is no shielded wire included in the kit although the instructions say there is!

So, can you recommend a shielded wire? Do I connect the shield to chassis ground on one end, both ends or?

[TheTinMan]

Personally, I use shielded wire for the run(s) from the input jacks to the grid of the first triode(s) and from the volume pot back to the grid to the second triode. In your build, there are two sets of inputs and two volume pots. Common theme - grids are sensitive!

You only ground the "quiet" end of the shield - at the input jacks and at the volume pot, respectively, in these cases.

I've been trying to find the web reference that shows how to separate the shield from the inner conductor and how to attach a lead to the shield so that you can ground it. No luck so far... sorry!

Chip

[Diablo]

Thanks again Chip. I found someone who sells RG174 coax cable for this application.

[Diablo]

I finished putting together the amp last night, and had some problems of my own doing. Did about 3 hours of trouble shooting this morning and fixed 2 stupid mistakes and found a bad board connection. Biased the power tubes to 20mA each and they match well. The normal channel is just perfect now, sounds great. The amp is very quiet in regards to hum. The vibrato channel has one issue that I need help on. Vibrato and reverb work fine as does the volume and tone controls. However, the guitar breaks up a lot earlier on the vibrato channel with a kind of buzzing distortion.

Any suggestions for trouble shooting would be greatly appreciated. I have a voltmeter, but no scope.

[TheTinMan]

Troubleshooting is the most difficult part of our hobby/passion IMHO.

What are the plate and cathode voltages on each triode of V2, V3 and V4? If they're not close to spec, check all component values.

My first guess is that there is an issue with one of the Vibrato channel tubes. V1 is a "known good tube", right? Try swapping it for V2 and/or V4. I've had trouble recently on two different Princeton Reverb builds with NOS 12AT7s - neither really likes the JAN Phillips 1980s production 12AT7s I got.

Are you hearing reverb and/or tremolo fine on the Vibrato channel?

Hope this helps,

Chip

[Diablo]

Thanks Chip for the info. After I posted the question, I figured I ought to try tube swapping. I have lots of new old tubes and good used tubes in my stash. I changed out all the preamp tubes on the vibrato channel from JJ to RCA and that didn't seem to make a difference. Then I desoldered and lifted one leg of the brightness cap on the vibrato channel. That fixed it....I think. I was originally hearing a ringing metal tone with an open E string. I don't know how the brightness cap was interacting, but it seemed like the cap went microphonic when the volume was louder than 5. I am hearing reverb and tremelo just fine now, and I was before I clipped the cap out.

I'm going to check all the voltages tomorrow to see if I find anything else peculiar.

[TheTinMan]

Diablo - you might try biasing the power tubes a bit hotter, depending on your plate voltage. If you're dead on the vintage 410, then 25 ma is about right for me. Sounds like you know this already, but just in case:

.025 ma at cathode - .001 ma for screen grid = .024 ma
.024 ma * 410 = 9.84 watts
9.84 watts / 14 watts "Design Maximum" = 70% dissipation

Here's a spec sheet for 6V6-GTA (http://www.mif.pg.gda.pl/homepages/frank/sheets/135/6/6V6GTA.pdf) showing the 14 watts. I know that earlier specs show 12 watts for "Design Center Max" plate dissipation. Even so, 24ma plate dissipation is "only" 80% of the 12 watt max.

All I'm suggesting is that you try it - you may like the tone better or you may go back to 20 ma after a couple of minutes.

Chip

[Diablo]

Today I went in and swapped the power tubes. I tried some used vintage tubes, but couldn't put together a pair that matched well, so I put in some NOS RCA 6V6 tubes and biased them to 18.6 mA and 22 mA - that's close enough for me. The plate voltage in this amp is a womping 460V, so I'm a little over 70% dissipation on the hotter tube. I wonder why Mojo uses a power transformer that puts out that kind of voltage? Consequently, every voltage I measured was 10-15% higher than the schematic. I also put in an RCA 5U4GB rectifier to complete the package. The amp was stable and behaving well on the bench for a half hour, so I installed it back in the cabinet for some guitar tests. Both channels sound great and all controls work well.

My only criticism of the Marsh kit is some ambiguous and missing instructions - one example is no mention of installing the ground for the bias supply board! That was one of my stupid mistakes for not checking the layout schematic. They also tell you to ground the wrong (right hand) side of one of the pots - that one I caught. They also don't mention a thing about measuring and adjusting the bias. Fortunately, I already understood how to do that. The best advice I can give is to check the schematic and layout to compare to the instructions on every connection. My last complaint is that they don't include a metal Fender logo....my amp looks incomplete.

[TheTinMan]

I've been fighting to get lower voltages in a 5F2-A build with a Mojo PT. My guess is that their transformers are replicas and do what a vintage PT would do with 110 VAC coming out of the wall, only we've got 120-125 VAC. Still, 10-15% is within vintage specs IIRC. (My B+ started out 50 volts over the 305 spec :rolleyes: )

Another guess is that Marsh can't sell a "Fender" logo with his kits. They probably can sell a "Fender" logo for your old Fender - you just have to order it.

Chip

[pila]

Mojo PTs seem to have too much HV. My first 5E3 PT was from them, and the HV was out of sight. I removed that one and used one from Doug Hoffman, which was in the ball-park on high voltage.

[MWJB]

"so I put in some NOS RCA 6V6 tubes and biased them to 18.6 mA and 22 mA - that's close enough for me. The plate voltage in this amp is a womping 460V, so I'm a little over 70% dissipation on the hotter tube." Have you tried biasing to 30mA per tube, the RCAs will take it, the massive screen voltage is potentially more angerous for the tubes than the plate current. The higher current may pull down your plate voltage to 425vdc (it usually does in BF Deluxes).

"Consequently, every voltage I measured was 10-15% higher than the schematic." No amps in real life match the Fender voltages on schems & layouts, 10-15% higher is absolutely normal.

[Diablo]

I went back inside the amp for a few finishing touches. I installed a 3 A/1000V diode (IN5408) on each of the power transformer secondary leads that connect to the anode plates (pins 6 and 4) of the rectifier socket. I did this to protect the amp in case of a shorted rectifier. Then I started testing some old rectifiers in the amp. The JJ GZ34 that came with the kit put out 460V to the plates at idle. A NOS RCA 5U4GB put out 432V. An old Silvertone 5U4G coke bottle put out 442V. An old JAN Sylvania 5U4G coke bottle put out 435V. The interesting thing was how much the plate voltage dropped under a load. With the volume cranked to 9 and a big guitar chord, I saw momentary readings on my meter around 310V. I was surprised there was this much voltage sag. I then decided to measure power tube watts under a load. Same conditions, vol 9 and a big chord.....each of the 6V6 tubes was momentarily pulling over 45mA....wow! I was again surprised there was this much current. Fortunately, the voltage sag under load reduces the tube watts to a reasonable level. The idle bias was retested and was the same as when I started (19.6 and 22 mA). I did find that the idle bias changed about 1-2mA with each of the different rectifier tubes. I left the Sylvania rectifier in place and buttoned the amp up. It looks like I don't have to worry about high plate voltage with this amp, as long as I stick with a 5U4G rectifier. Now to go work on my playing. I want to thank everyone on this forum for all the great information and help with the Deluxe Reverb. Without the internet, I never would have even entertained the thought about building this amp or fixing up my Ampeg.

[TheTinMan]

I'm really glad it's worked out well for you!

Are you certain that the PT can handle the higher heater current draw of the 5U4GB tube? IIRC it pulls almost 3 amps vs. only 2 amps for a 5AR4/GZ34.

Chip

[Diablo]

I'm really glad it's worked out well for you!

Are you certain that the PT can handle the higher heater current draw of the 5U4GB tube? IIRC it pulls almost 3 amps vs. only 2 amps for a 5AR4/GZ34.

Chip

No, I'm not certain, just keeping my fingers crossed. Bruce (Mission Amps) recommended it and others on the net claim it's not a problem for the Deluxe Reverb. It's my understanding (maybe not correct) that many Fenders from the mid 1960s came with the 5U4GB, and there was some confusion on the schematics about the specific rectifier choice.

[Bruce / Mission Amps]

No, I'm not certain, just keeping my fingers crossed. Bruce (Mission Amps) recommended it and others on the net claim it's not a problem for the Deluxe Reverb. It's my understanding (maybe not correct) that many Fenders from the mid 1960s came with the 5U4GB, and there was some confusion on the schematics about the specific rectifier choice.For what it's worth... I think the Marsh kits are just MOJO amp kits and I've always been under the impression that the power tranny they copied "originally" was a silverface Deluxe Reverb PT... which used 5U4GB rectifiers.

http://www.mojomusicalsupply.com/item.asp?pid=18154&pg=45008&id=MOJO761

Note: I don't know if this is the PT supplied in your kit.

Regardless, IMHO no great sounding Deluxe reverb ever has more then 440vdc plate voltage and the best ones are around 420vdc or less for that sweet-juicy, black face tone.
What you need to do is increase your idle current to about 26ma-28ma.
The tubes will be hotter and your plate voltage will drop more but the amp should sound really good too.

[phylomatic]

You didn't happen to take pictures did you?

[Diablo]

For what it's worth... I think the Marsh kits are just MOJO amp kits and I've always been under the impression that the power tranny they copied "originally" was a silverface Deluxe Reverb PT... which used 5U4GB rectifiers.

http://www.mojomusicalsupply.com/item.asp?pid=18154&pg=45008&id=MOJO761

Note: I don't know if this is the PT supplied in your kit.

Regardless, IMHO no great sounding Deluxe reverb ever has more then 440vdc plate voltage and the best ones are around 420vdc or less for that sweet-juicy, black face tone.
What you need to do is increase your idle current to about 26ma-28ma.
The tubes will be hotter and your plate voltage will drop more but the amp should sound really good too.

Yes Bruce, you are correct. The Marsh is a Mojo kit. I don't know if they change any of the components or just include their own instructions. The power transformer is the MOJO761, same as above. I'll try cranking up the idle current and see how it sounds. Thanks for the advice.

[Diablo]

You didn't happen to take pictures did you?

Not yet. I'll shoot some and see if I can figure out how to post 'em. What are you interested in seeing?

[TheTinMan]

Not yet. I'll shoot some and see if I can figure out how to post 'em. What are you interested in seeing?

Inside the amp - power supply section, preamp section, tube sockets, control pots from the back, plus what the finished product looks like...

Photobucket.com is ok for posting a short slide show but there are other alternatives.

Chip

[Diablo]

OK, let's see if this link works to Photobucket.
30 images for y'all. Not the neatest I've seen, but what the heck....it works.

http://s268.photobucket.com/albums/jj29/Diabloted/Marsh%20Deluxe%20Reverb/

I also rebiased to 26-28mA as per Bruce's suggestion. The plate voltage dropped to 423V with the Sylvania 5U4G rectifier. I haven't had a chance to play a guitar through it at this bias.

[phylomatic]

I just wanted to see the finished product. Just out of interest I read the whole thread and it felt a bit anti-climatic without getting to see the finished product. Very interesting read and looks like you did a good job. I'm completely new to this so I don't know if that means a whole lot, but it seems like a lot of fun.

[Diablo]

No real serious changes at all except:
use five 22uF-500v TAD main B+ filter caps (I think they are actually SINO import caps, but excellent),
Use a real NOS 5U4GB rectifier tube.


Bruce, I have a question for you. I find the bass notes more than a little farty at higher volumes. I put in the stock 16 mfd filter caps that came with the kit. Do you think the 22mfd caps would make a good improvement? I was also thinking about trying a Weber SS rectifier (the no sag type) replacement - one of those copper caps to improve the bass. Do you think the amp would stand the higher voltage and would it improve the bass?

[Bruce / Mission Amps]

I always use two parallel 22uF@500v caps there myself.
I think most of the woofie tone in these is from the full frequency gain of the preamp tubes... (try 4.7uF caps across the cathode biasing resistors instead of 22uF to 25uF) and the little cap that drives the phase inverter (don't use more then .0022uF to .0047uF) .... plus the giant .1uF caps that drive the power tube grids. Those can be reduced to .047uF with very little loss of tone.
Another good trick is to reduce the gain and balance of the phase inverter 12AT7 stage a little by replacing the 27K tail resistor with a 33K to 47K and the 470 ohm biasing resistor with 820 to 1200 ohms... experiment.

[Diablo]

Thanks Bruce for the great information! I did some more testing before I started to order the parts and discovered what causes the farting bass - it's just characteristic of the speaker. The speaker I ordered with the amp is a Weber 12A125 Alnico designed for early breakup. I A/B tested the amp with the Weber vs the stock Eminence Legend 12" speaker in my HRdeluxe. The Legend has pretty clean and punchy bass notes even at cranked volumes. It also is quite a bit louder than the Weber. However, the Legend doesn't have anywhere near the crunchy distortion of the Weber. Now if there was a way to use both speakers and control the amount of signal that goes to each one to blend the sound I want........

I think I just learned how strong an effect speakers have on the sound of the amp.

[Diablo]

I installed a Celestion G12L (25 watt) speaker in place of the Weber and it made a huge improvement on the bass notes. A buddy told me about the tremelo lift mod, so I had to try that too. I disconnected the circuit feed wire to the tremolo intensity pot and soldered it to one side of the unused ground polarity switch. I soldered another wire from the other side of the polarity switch to the tremolo intensity pot. Now the polarity switch is an on/off switch for the tremolo lift. This gives the amp a switchable gain boost on the rev/tremolo channel.