trinityamps.com

Here are few bad phone pics.... Once everything is sorted out, I will clean up the lead dress. It is dead quiet, and I've got tons of room for upgrades (Red Box, PS for the relay, possibly an effects loop. It also drops right into my Swanson 2-12 combo cab.







The faceplate on there is a leftover one I got for my JP504. I messed up when I ordered it, so I had an extra for this project. Once I get it all up and running (LEDs etc.) I'll have a correct one made.

I'll play with it some more. As I said, it's darn close..... It definitely works.




That would explain why it sounds so good!




I put a Mullard ECC81 in as as soon as I knew it was OK. I only ran the 12ax7 in the PI for the first fireup, so as to not risk a good Mullard. I'll have to put it side by side with my other Hiwatts. As soon as I started playing with the Triwatt, and started messing with the volumes, It struck me that it sounds a lot like my 2 holer as far as gain goes. With humbuckers, it starts to break up at around 10:00 with the channels linked (which is the way I run my 2 holer using a Y cable. My JP is similar to my 2 holer in this regard). My 4 holer seems to have a bit more headroom, but I haven't played it too much since I built the JP504 last year. I recall being able to use quite a bit more preamp gain (again, linked) before it started to break up. I'll drag the 4 holer out when I go home and do a side by side comparison.....

It might be that I am used to the headroom of the 50 watters. You can run them loud enough to damage hearing without breakup!



Definitely.... It should work great. I played a bit with my pedals (blasphemy!) and it sounds great with the same ones that sound great with the Hiwatt.



Sweet..... I'll order some Red Lions!

When I was researching other lower-power Hiwatt style amps, made by companies such as Music Ground/Hiwatt and Reeves, I was really surprised by how they had deviated from the classic Hiwatt formula with these amps, and really ended up producing some slightly oddball hybrids.I just couldn't, and still don't, get their logic for doing that. With Trinity's Triwatt, I wanted to do the absolute bare minimum changes needed to be able to run 6V6s or KT66s in the amp, plus adding the switchable Overdrive stage. And even for that's based on the Biacrown era Hiwatt design. OK, I'll get off my soapbox now...


The Triwatt's preamp is the cleanest of all the early '70s Hiwatt preamp versions (when the Overdrive is disengaged). It uses resistive mixing and has no cathode bypass resistors apart from one on the Bright channel front-end triode. So I think what you're finding is indeed the result of it being a 20W amp vs 50+W amp.


That's no blasphemy with Hiwatt amps.


As you would expect, overall volume is only slightly more, but you get more clean headroom. Those Red Lions are beautifully made tubes too, complete with the vintage style side getters.

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Great tones come in small glass jars!

Well, I played around with this thing more today, and I must've done something wrong somewhere in the build.

I compared it to my 4 holer using the same cab. There is definitely a lot more gain than my 4 holer, even more than my 2 holer or JP.. I am using NOS 12AX7s in the preamp, except for the PI, which is a Mullard ECC81. All of them came right out of my 4 hole DR504 clone after I had just played it, so it's not a tube issue.. I have JJ 6V6s in the power section.

I can't get that big Hiwatt clean out of it at any volume. I don't think it's a function of the wattage, as my Marwatt has a ton of headroom, and it's only 18 watts. The overall volume is lower than the 18 as well.

It's got a nice punchy, on the verge tone even with the preamps at around 9:00, no matter where the MV is set....... It thins out considerably at lower preamp settings.

My B+ is around 450 with an input of 124VAC. I ran it at 120 with my variac, and it lowers the B+ to about 438.

The heaters are running at 6.5 at 120 and 6.7 at 124.

Bias is -38.

I did a quick trace against the layout, and nothing seems to be out of whack, but there has to be something.

I'll make a voltage chart tomorrow and see if anything pops out. I'm sure it's something really stupid that I've missed!

Any ideas?

I'm afraid nothing comes to mind as being very obvious. It might just be a resistor with the wrong value somewhere. A mored detailed voltage check would be good to start with (using a 12AT7 in the PI), comparing with the voltages shown in the build guide. Your B+ looks about right. The amp should definitely sound louder than your 18W, with lots of tight clean headroom.

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Great tones come in small glass jars!

The more I ponder it, the more I think I need to concentrate on the power section. I'll bet the problem is there somewhere....

Voltage check later.....

All right.... Voltages are in....

V1
1-142
2-0
3-01
6-133
7-0
8-01


V2
1-182
2-0
3-01
6-108
7-0
8-0

V3
1-273
2-66
3-70
6-187
7-0
8-01

V4
1-243
2-72
3-72
6-249
7-63
8-72

6v6's

1-0
3-441
4-416
5- -37
6- -37
8-0

Phil, is the builders guide available on the site somewhere? I don't have one!

Also, are the V2 grids supposed to be connected via the switch (purple line on the layout) with the OD switch off?

The OD switch "OFF" bypasses V2A and feeds directly into V2B . Yes this connects the grids.

Only on-line docs are here: viewtopic.php?t=1567

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks Stephan,

I was hoping that it was something that simple..... I'll press on!

I still can't find the builders guide with the voltage chart that Phil referred to.

Ok, I'll post it soon.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks Stephen!

TRIWATT 6V6 Voltages PDF

also posted in resource section

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Well, after being laid up with the flu since Saturday, I finally felt good enough to tackle this thing again. As usual, a bonehead move on my part was the culprit... The .022u cap going to plate 2 on V1 was heat damaged when i soldered it. I left the leads too short. I removed and replaced it, and voila, normal volume with the boost disengaged!

Now, I need to pull some of my favorite tubes out my other amps and see what it likes......

Great news! Now you can go ahead and enjoy some classic Hiwatt tones.

Sorry to hear about your 'flu BTW. Still I always say it's better to have swine flu than mad cow disease.

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Great tones come in small glass jars!

It's definitely a lot better, but I still think there's an issue. The OD is a LOT louder than I can even make the amp when disengaged, but it's not that much more distorted.

The way it's working now, I'd have little use for the footswitch. By the time I've got a noticeably more gain with the OD, it is far louder than with it disengaged. FWIW, with the OD engaged, I get more headroom and can get that nice loud Hiwatt clean. There has got to be something wrong, but I'll be damned if I can figure it out.

I tried wiring up V2 like a 4 hole Hiwatt, only using pins 6,7,and 8, and eliminating the 1uf cathode cap. It seemed to react a lot like my DR504, but the preamp volume and headroom simply wasn't there.



It was a butt kicker!

Not quite sure what you've got happening there. It's worth pointing out that the gain boost you get from the Biacrown style Overdrive stage has a very different vibe to say a Marshall JCM800's gain. An important thing to remember about the Overdrive (OL) stage is that the Overdrive control on the front panel controls the signal level coming *out* of the stage and hitting the rest of the preamp.

So first of all, if it's working correctly, you will get a jump in volume level when you the Overdrive kicks in, due to the increased signal level if the control is turned some of the way up. At lower settings of the control, you will instead get no jump in volume or even a reduction. One way I like to use the Overdrive control is to turn up the Bright and Normal volume controls quite high, and reduce the Overdrive control to the point where there's little or no boost in volume when engaged. Extra distortion will then be generated purely within the Overdrive stage. If you use the amp this way, then it makes sense to have the foot switch.

bgroup also likes to do the opposite to get a different type of feel, ie to turn the Normal and Bright volume controls down fairly low and wind the Overdrive knob up instead. Set this way, you would probably leave the Overdrive engaged and control the amp more from the guitar. At the Triwatt launch party gig, Lawrence played the entire set with the Overdrive left switched on.

One of the things I was really surprised to find was how amazingly touch sensitive the amp becomes with the Overdrive engaged. When you drive it hard from the guitar, it delivers a great roaring grind. With H/Bs it will give you great metal tones. But roll back the guitar volume and/or pick gently, and you get crystal sparkling cleans, which are almost acoustic-like.

So play around a little more with the amp, and see if what you're getting matches what I've described here. If not, you will need to investigate further. The amp does kind of have two different personalities. Without the Overdrive stage it should behave and sound very much like a lower power version of a 4-holer. You will be able to get the power stage to distort at higher settings of the MV - while loud it won't be painful. That kind of overdrive from a four-holer would have your ears bleeding.

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Great tones come in small glass jars!

All righy then......

I just spent a few more hours with this thing.... I found the problem with the low volume. It was a bad physical connection at the "apex" of the 2 470K resistors between the normal and bright volume pots. I redid it, and now I've got that "in your face" Hiwatt preamp clean with the boost disengaged.

Overall it is exactly what I was looking for. At the same volume levels as my 50 watters, everything sounds fuller, especially my pedals, since I can bring the master up more. My Rat sounds especially tasty with it.

Now, I gotta wire up the PS for the footswitch. I think it will work well as a lead boost....

Most excellent. Specially the 'in your face' part. Feels like a breakthrough huh?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Definitely...... I go through this every build. It's always something really simple. I really like the amp. It's the perfect wattage for what I need it for.