Amp build: Allen Sweet Spot

[duhvoodooman]

I've been looking around at smaller Fender "Blackface" era amps (Deluxe Reverb, Princeton Reverb) for a while, hoping to find one in good condition and (preferably) with all original parts, with the exception of the tubes and filter caps. But after missing out on a couple of good deals and seeing a mixture of amps that were either (1) stunning vintage examples and priced accordingly, or (2) more reasonably priced but with less desirable pedigrees, I decided it was time to scratch the Blackface itch in some other way.

I started looking around at kits, and the name of Allen Amplification kept coming up. As I understand it, it's a one man operation run by David Allen, and has a reputation for top quality amps based upon the classic vintage Fender designs, but with some more modern design improvements. In addition to selling completed amps, David also offers his various designs in kit form. I was looking for a reasonably low wattage amp with both reverb and tremolo, and I found that his Sweet Spot amp, based upon the Princeton Reverb, fit the bill perfectly. Allen's amps and kits are certainly not the cheapest available, but they have a great reputation for quality, design excellence, customer service and--most importantly--great tone. I placed my order on Wed. Apr. 29, and the chassis kit was delivered last Friday, May 3. I went with a 1x12 combo, but the cabinets are built to order and take about 6 weeks.

The Sweet Spot is what David calls a "bares bones" kit, so it does not come with detailed, step by step instructions and is therefore intended for reasonably experienced builders. The kit documentation included a parts list, schematic, layout diagrams of the main eyelet board, filter cap board and chassis wiring, assembly tips, and operating instructions. Going through the kit contents, I found that there had been one oversight--a bag full of hardware had been left out. I contacted David by e-mail on Saturday and received a response within a few hours, and the missing parts will be on their way on Monday. Now, that's the kind of customer service I was hoping for!

Even with the missing hardware, I still had plenty I could work on. I populated both eyelet boards, including connecting the "flying leads", mounted the control pots, input jacks, tube sockets and several other parts on the chassis. I also wired the resistors into the input jacks and power tube sockets, did most of the wiring between the control pots, and connected the bright switch. That's pretty much as far as I can go now until the missing hardware arrives. Here are some photos of the progress so far:


http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_main_board.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_main_board_underside.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_filter_cap_board.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_chassis_pots.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_chassis_sockets.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_chassis_sockets_top.jpg

And here's a special graphic for Rev Rawk:

http://ncsalceditor.files.wordpress.com/2011/12/bronx-cheer.jpg

[marnold]

Hehehehe. :D Looks like it's a serious amph! I can't imagine trying to build one without a lot of hand holding.

[piebaldpython]

Wow........you da man Vood. Sweet looking build. Looking forward to the completed amp and how it compares with your Champlifier. What gets jettisoned with the new kid coming into the fold?? lol

[Robert]

Sweet! I would love to have such an amp. After someone has built it though :D

[Tig]

Dang, the Sweet Spot is the Allen I've been GASing over the most! Allen's are supposed to be incredible, so you should really like this one.

http://markweinguitarlessons.com/forums/images/smilies/munch.gif

[Monkus]

Wow, DVM skillz.... ironically, I was looking at these recently, then common sense took over.

[duhvoodooman]

Received the missing hardware on Wed. and dove back in. Finished wiring it up on Thursday evening, but too late to test. Plugged her in last night, and son of a gun--everything worked the first time! http://www.thefret.net/images/smilies/dance.gif http://www.thefret.net/images/smilies/very-happy.gif http://www.thefret.net/images/smilies/Dude.gif

It'll be a while until the cabinet & reverb tank arrive, but that won't stop me from playing through the "naked chassis" until then! I've only had a few minutes through it at this point, but what a gorgeous, Fenderesque tone! More on that after I've logged some significant time on it.

Here's a bunch more photos:

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_front_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_rear_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_front_panel_960.jpg

[duhvoodooman]

More:

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_left_front_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_right_front_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_right_rear_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_left_rear_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_top_trannies_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/chassis_finished_top_tubes_960.jpg

[Tig]

Awesome, DVM! :thumbsup

[piebaldpython]

Damn.........you do some NICE work Vood.

[marnold]

http://static.giantbomb.com/uploads/original/0/3189/2421129-2629336_darth_vader___impressive_color_lrg.jpg

[Tig]

http://static.giantbomb.com/uploads/original/0/3189/2421129-2629336_darth_vader___impressive_color_lrg.jpg

:D
http://markweinguitarlessons.com/forums/attachment.php?attachmentid=7847&d=1368158338

[duhvoodooman]

Geez, this thing sounds great! For a fairly low wattage amp (18W with 6V6's, ~25W with 6L6's), it has a beautiful sounding bottom end--great taut, thumpy bass even through a single 12" speaker. I've been playing it quite a bit through my 2x12 cab with a pair of Greenbacks, and it sounds just huge. Not surprisingly, the amp really excels at cleans--just great clarity and bell-like tones. I was a bit concerned that the highs might be a bit piercing, but that doesn't seem to be a problem at all. The bridge pickup on my AmStd Strat can be pretty ice-picky through a couple of my amps, but it sounds great through the Sweet Spot (so maybe I'll use it more!). The "middle/raw" control is very cool--acts like a simple mids control up to about 3, and then starts to add gain and dial out the effect of the tone stack. Basically, you're adding back in the signal that would normally be bled off through the tone stack.

I really haven't been able to crank the amp up enough to check out its overdriven tone in my small "cave", but I'll try running it through my MiniMASS attenuator and check that out before too long. In the meantime, I'll use pedals, which the amp seems to take very well. Unfortunately, David tells me that there are nine cabinets ahead of mine in his production queue, so it's going to be a few weeks before I get to mount it into the cab with the Weber 12F150T speaker I picked up on eBay for it. No big deal--will just continue to run it through one of my two speaker cabs in the meantime....

[kidsmoke]

Wow........you da man Vood. Sweet looking build. Looking forward to the completed amp and how it compares with your Champlifier. What gets jettisoned with the new kid coming into the fold?? lol

yes?? What does get Jettisoned???

Remember, PBP, that Champlifier now calls Chicago home, and gets schlepped from cave, to class, to bar, to cave...weekly. Gets lots of love. And keeps me checking for DVM clearance sales regularly.


If I could get the tone of this Champ a small venue giggable volume.....well, that'd be it.

just this past Friday night....

One pedal one amp, both DVM builds.

http://i93.photobucket.com/albums/l58/tiokimo/null_zps8f5621a5.jpg (http://s93.photobucket.com/user/tiokimo/media/null_zps8f5621a5.jpg.html)

Mic'd the Champ with a SM-57 and ran it through the PA.

[duhvoodooman]

Bad news for you gear vultures--the Sweet Spot is exempt from the "one-in-one-out" rule (special circumstance, don't ask). So nothing planned to go on the block at this point. Sorry to disappoint.... ;)

Sounds like you could use one of these, TK: http://byocelectronics.com/amps-cabs/amplifiers/tweedroyalcombo.html

[piebaldpython]

"Special circumstance".....what kind of crappola is that? lol

Tio, yes I know the Champlifier is in Chicago. But I figured that since DVM is NOT yet a doddering-old-coot, lol, that he would probably remember (or have sound clips) of how the Champ sounded and be able to compare/contrast his 2 hand/built amps.

Yes, I saw the link....and NO you, or anybody else for that matter, do not want me near a soldering iron. Plus, the money I thought I would have for one never materialized. SIGH!!! Still, it's nice to dream about having one.

[kidsmoke]

Bad news for you gear vultures--the Sweet Spot is exempt from the "one-in-one-out" rule (special circumstance, don't ask). So nothing planned to go on the block at this point. Sorry to disappoint.... ;)

Sounds like you could use one of these, TK: http://byocelectronics.com/amps-cabs/amplifiers/tweedroyalcombo.html

Yep, I couldn't agree more, and I was hoping that's exactly what you might have thought about moving. Rather have one "from the bench of DVM".

speaking of which (before you forget how it sounds, with the Sweet Spot coming online....) How are you feeling about that Royal?

Last night at class, I forgot my Klone at home somehow, so I had to turn the amp up to 7 to get the breakup, played my RS-2, bridge, and TORE through a mash up of Dear Mr. fantasy/Can't you see/Dear Mr. Fantasy....good lord I just love this box, vood. Really. I know it's getting old, but it's arguably the most satisfying purchase I've made since embarking on this journey.

[duhvoodooman]

The 1x12 Sweet Spot cabinet arrived today, and I mounted the chassis and a Weber 12F150T speaker I picked up on eBay. I was out of the house most of the evening, so I really haven't had a chance to play it in the cab yet, except for a quick functional test & confirmation that the reverb works (it sure does!). Also installed a pair of SED "Winged C" 6L6GC power tubes and got them properly biased, so looking forward to making some serious noise tomorrow. http://www.thefret.net/images/smilies/rockon.gif

Pics of the finished amp:

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_cab_front_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_cab_faceplate_960.jpg

http://duhvoodooman.com/miscimages/musical/AllenSS/Allen_SS_cab_rear_960.jpg

[Tig]

It looks great! I like the bias jacks being so convenient.
It has been said that Allen amps do Fender better than Fender. Inquiring minds want to know. :munch:

[piebaldpython]

Damn Vood........looks great.

Vood....if you get a chance.......could you comment on the difference (pros/cons) in tone from your Champlifier to the Sweet Spot?? Thanks.

[duhvoodooman]

.....could you comment on the difference (pros/cons) in tone from your Champlifier to the Sweet Spot?? Thanks.The differences are vast. You're talking about a 5W single-ended Class A amp with an incredibly simple Fender Tweed era circuit design vs. an 18W (or ~25W with 6L6's installed) class AB push-pull circuit with many more features (TMB tone stack, tube-driven tremolo and spring reverb). So really night and day. The Champlifier has the typical mid-heavy Tweed tone and is very easily pushed into a really nice bluesy overdrive. The treble is pretty mellow, and the bass is definitely on the soft side, and will get pretty muddy sounding if pushed too hard (the term "farting out" is often used for this characteristic). Head room is pretty minimal, so it's not a good choice if you're going for a clean tone with any appreciable volume, unless you can mic the amp. But it's a great blues & classic rock tone, if you can live without a tone control or a lot of volume output and bottom end. And it makes a great bedroom/practice amp.

The Sweet Spot has the quintessential Blackface amp tone--clear, sparkling highs and nice, firm thumpy bass. Mids are noticeably scooped, though the Sweet Spot has a combined "mids/raw" control that acts as a typical mid control for about the first 25% of its sweep, but thereafter it basically dials out the effect of the tone stack, adding more mids and a lot more gain, as signal normally lost through the tone stack is added back in. At that point, it sounds kind of like a Tweed-Blackface hybrid--plenty of mids and overdrive on tap, but with the BF treble twang and firm bass. Really a nice sound! But where this amp really stands out is its clean tone--many players consider the Fender Blackface cleans to be unmatched, and it's easy to understand why when you hear this amp. Add in the spring reverb and the lush tube-driven tremolo and you have a very versatile tone machine. It won't do high gain stuff, but it takes pedals well, so you can get to harder rock sounds that way. Forget about death metal, though. It's also quite loud for home use, so if you want to push the output stage into overdrive, you'd better plan on using attentuation of some sort.

[marnold]

Cool! I'd love to hear some clippage as time permits. Looks like your usual perfessional job! Even though I tend towards the hot-rodded Marshall type tones, I have a soft spot on my heart for a Blackface. If I ever got a second amph, that would probably be it.

[piebaldpython]

Vood, thanks for the explanation. Sounds like I NEED one of each........to cover ALL the territory I might venture into. lol