a couple pics of this 6L6SE (Lone wolf project amp) i built from a Strauss SHW-10.
The Strauss was essentially a 5F1 champ circuit with a 6L6 instead of 6V6, and a 10" Celestion Tube 10. It was also about the worst sounding 5 watt tube amp ive heard me play through. i originally planned to go through it and sort out why it sounded so uptight, make it a champ with a 10"...though i dunno about that speaker... but then i just decided to gut it and use the chassis, sockets and transformers to build the project amp on the LW site.
Amp cost $150 delivered, i put about $60 parts into it. I'm actually running a 7027A instead of the 6L6GC that came with the amp, because i found a pair of RCA 7027A tubes in an old PA i had.
amp fired up well. runs very quiet. has 4 and 8 ohm outputs, hi and low gain inputs, treble cut tone control is the best one i've built yet and 90% useable sweep on the volume control. this is definitely a 'harp amp' rather than a modified guitar amp. i want to make a couple of adjustments still and try some different speakers but its quite promising and i learned quite a bit from the build...from my mistakes as usual. and turned what really was a bit of a dud into something that feels much better...anyway, photos and if you're interested in building a small harp amp, i think this is quite cool. sounds pretty good across the volume range too so maybe more fun as a 'bedroom' amp than most 5w jobs
Looks good Supe. I see you have the power R's up off the board so they cool well. It is a smart looking amp also.
My only advice would be that those AC heater wires do not have to be twisted that tightly. 2-3 twists per inch are sufficient to stop AC hum induction. Twisting those wires tightly puts stress on the insulation which may lead to failure (short) when things heat up in there.
All you need is a nice cover. A small sweat shirt makes a great temporary cover. Tuck the sleeves in and the neck hole gives access to the handle. Nice job mate...BN
Thanks for those tips BN. It is good to know about the twists, i'll remember that. And my amps do need covers. I keep them in my utility room, which is pretty much a bedroom with no bed. Thanks Arne, and for all your help while i build these things. Great to have someone to ask, sometimes it is about working out what is the question. I should add, the rectifier in these photos is the one from the LW design, but it does not work with a transformer on which there is no centre tap...such as the one in this amp! I got as far as testing and found i had no current. So then i learned what a bridge rectifier is. I had to add 2 diodes and tie it to ground. Simple, then it worked! Also my screen voltage is about 40 volts over the design level,and preamp plate voltage rather high also, so i have also done some learning in how to calculate how much extra resistance is needed to bring those closer to spec. The project has been around a long time, about 8 years now i think. Anyway, im glad to have built this. Each time i build an amp, they are feeling a bit more personal to me. 'Zab, i have no sample yet...i will settle these voltages down and see if i can get it a little tighter sounding, perhaps adjust the power tube bias, then i will record with it
Supe, you can adjust the PS node voltages for screens and pre, then use the extra voltage in the power amp B+. This gives you the proper tone but with a slightly higher wattage output. The screen voltage on power tubes should be a few volts below the plate V. Raise the value of the resistor feeding the screen grids first, the preamp voltage will drop also as those R's are in series. This may result in the preamp plate voltage being close to what you want. Higher preamp plate voltage gives more clean headroom and gain. Lower is pretty much opposite. You may or may not like the results of preamp voltage adjustments.
Arne is the man! He helped me with my Masco build. Great fellow and very knowledgeable...BN
Last Edited by Barley Nectar on Jan 28, 2016 8:38 PM
Hang on BN! That post has given me a bunch of questions! What's the PS node? The screen resistor is on a separate branch, the preamp voltage comes off without having to cross the screen resistor. I upped the preamp resistor from 132k to 150k but voltage on the plates only dropped 6-7 volts. I was shooting for around 130, it's just under 160 atm. Power tube plate is running 360 volts (near enough to spec 355) screen was at 285, after increasing resistor from 27k to 37k now at 269. Design spec is 245. Cathode voltage was at 15.5, after dropping screen voltage cathode now at 14.9
Amp is a bit dirty for my taste and the dirt is a bit aggressive but no doubt many would like it.
increased dropping resistor for preamp to 200k which brought plate voltages on the 12ax7 down to 135 and 133 compared to design spec of 127 and 140. preamp cathodes are running just over 1 volt each
upped the resistor for the screen (R13 in Schematic) to 50K and this brought screen voltage down to 250...had been 285. Cathode voltage now just a shade under 14 volts. Power tube plate has jumped to 270 volts from 260.
Tested and much happier with the sound now. Still undecided about the Celestion but heard some things i like so will let it be for a while and do comparisons when i get opportunities.
one thing about it is much louder than these 8" amps and bigger bass as would be expected. at least the celestion is not flabby in the bass.
now i have to redesign that faceplate. it says 'volume' under the tone knob...
oh, the base unit for this build was sold in Australia as 'Strauss' (using a dormant, redundant brand name from the 70's and slogans like 'the legend is reborn'...which was hilarious because the only legendary thing about Strauss amps was their propensity to catch fire on stage due to their crappy under-specced transformers and general shoddy build quality which was done by underpaid unqualified workers)...but i digress... yes the base unit...sold in Europe as 'Golden Ton'...in Australia the vendor had the audacity to ask over $500 retail for them when they first came on the market...'hand-wired' don't you know...
The european distributor said they quickly stopped selling them due to burnt transformers...but the Australian story is that transformers were changed here before they went on sale...personally i dont believe it because the transformers in my amp look exactly like those i can almost see in the pictures on this page. those pictures give a small idea of what i started with anyway... so...it may blow up or it may not...if it does...i may rebuild it if theres enough left. this has served as a proof of concept anyway, even if the transformers prove to be short-lived
Last Edited by SuperBee on Jan 29, 2016 4:20 AM
Power tube plate went from 360 in your previous post, to 260 in last post. Missprint i suspect. Anyhoo, yes, you have it figured out. I had not looked at the schmo when I gave the PS recomendations. That screen setup is a little different. I should have taken the time to look at the schmo. Running that screen 100V below the plate is different also but Randy knows his stuff and the proof is in the tone. Nice job Supe...BN
heres a few minutes of farting around, plugging into both inputs of this amp and comparing to a 5F1 clone i built. theres a bit of commentary explaining the various setups and settings...starts of with the low gain input of the 6L6SE, mic is a shure CR.
i want to try this with some different 10" speakers. i see we get the WGS speakers at reasonable price in this country...i think i may have heard good things about them?
Well done Supe, nice demo. I think as far as Chicago tone goes, the 6L6 in the high gain input around 7:45 is the winner. You are pushing it to the edge there and that is where the horn like tone lives. You say you don't really care for the added distortion yet when you are playing the 6L6 amp at 8:37 you were getting carried away. That is because , you are into it! I think you new amp sounds wonderful, and so do you. Good job mate...BN
Nice clean build Super. - I built one a few years back, I can't remember the voltage measurements or any other specifics. I built it pretty much as designed, - creativity with the cabinet excepted. I still like it, - but it doesn't quite sing like my old GA 20 and GA 6 do.
Theres a lot of BS'n until 1:45 when I start to play though it.
Last Edited by bonedog569 on Feb 02, 2016 2:05 PM
Hi BN, thanks for listening and for comments. Made me feel good about it, much appreciated. I do enjoy the amp building and learning side of things and glad we can share this stuff here. Hi Bonedog, thanks for posting your video. I have watched it a few times; I think I saw it when you first made it and I watched again when deciding whether I wanted to build this amp. Brings a different level of interest now in comparing your sounds with mine...trying to listen past the player and hear the signature of the amp in the sound...it's interesting. Our garage jam has been moved forward to this weekend, so I will take this one and the Princeton for a run. I'm not playing out much arm, just this jam every month or 3 weeks, so I try to take a different amp or two each time so they all see some use and I can remember what they are all like. Sold 2 of my 3 bigger amps, so just the 410 left now, which I'll keep. Now that I've sorted out this 10" unit, I think it's time to pay attention to the old Ampeg Jet. That will be the first PP amp I work on
The Franken-Jet, I remember that. What are your plans, put it back to stock? Put in a different circuit? Experiment with it as is? How does it sound now?
At the moment all I can say is that it has very little sweep on the volume. It goes from nothing to squeal in a very short space. The spot in between is like one level. I find the spot below feedback that still has sound and it's ok-sounding but I just played it one time. So first plan is to get it on the bench and map it, compare to schematic and understand what changes have been made. The guy who had it told me he'd been after more clean headroom, but he couldn't tell me what he'd done. I know it's running 6L6 tubes. He talked about the PI tube and changes made in that regard (no detail). I couldn't see a different tube in PI, but I did notice the rectifier was gonna be kicking out more voltage than the design spec tube, and that made sense to me considered with the 6L6 tubes and his stated quest for headroom. I've heard the Jet is a pretty good design for harp...so I'm certainly thinking about putting it back to an original circuit and kicking off from there. When I break it free and work out what's going on with it I'll try and document it. i like amp discovery threads.
Pretty cool tone, I like that amp. Do you think that the HT10 from LW sounds similar? ---------- Sorry for any misspell, english is not my first language.
Sorry Rogonzab, I don't know about the H10..this amp I built is from an 8 year old design of Randy's. I'm not sure if he incorporated any elements from the 6L6SE in the HT10. What I can say is that I took this amp to jam today, and also took my Princeton Reverb. I took a 12" cab as well. The LW design amp stood up really well. It was better through the 12" The Princeton was a bit feedback prone by comparison, until I plugged into the low gain input. Interestingly enough, I didn't think the Princeton was significantly louder. I love the PR, so that's an indication of how pleased I'm feeling with the 6L6SE. When I took the amp to this jam in it's original form, it was unbearable. The new circuit has improved it out of sight. It sounded very good with the LW reverb pedal too. And my fairly new crystal mic (MC151) sounded really good with it too. Better than in any other rig actually.
"Interestingly enough, I didn't think the Princeton was significantly louder".
Proof of the point that feedback is a function of your environment. Both those amps were in the same room with the same acoustics and were both capable of the same volume levels. So when pushed to the edge, they were both about the same loudness.
Congratulations to ya Supe. You will be playing that amp a lot and deserve to be prowd! ...BN
