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PostPosted: Wed Nov 20, 2019 12:40 pm 
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This past weekend I almost completed my Triwatt build that I've been slowly working on since mid-August.

It's not as neat and tidy as most of the builds I've seen here and other online forums, but I think it's reasonable.

A huge thank you to Gertjan2411, the pictures of his build were immensely helpful to me, particularly when I was getting started. Once my build is officially done and tested, I'll try to post some more pics.

This will ultimately go into a 1x12 combo cab that Trinity made for me. I'm planning to use the Reeves Vintage Purple Speaker, unless someone suggests a better alternative.

Main question I have now: the primary (*) side of my output transformer has five wires, whereas the documentation and pics here only show three. In addition to the red (CT), blue and brown (primaries), I also have blue-white and brown-white leads. Does anyone know what these are for?

I've already done one check that all my connections are correct, and intend to do at least one more before I apply power. I will certainly follow the "first power-up" directions, but does anyone have any suggestions for more sanity checks I can do before power is applied? I've been doing DIY electronics for quite a while now, but this is my first tube amp, i.e. first project with super high voltages. As much as I want to rock out with it, safety comes first!

Thanks!

(*) Edit 1: in my original post, I accidentally wrote "secondary(ies)" instead of "primary(ies)" in my question about the output transformer.

Edit 2: added lots of pictures.


Attachments:
File comment: Obligatory gut-shot. Taken before completion - note missing jumper wire in bias circuit!
P_20191117_173159.jpg
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File comment: Completed, in 1x12 cab, front view.
front_full.jpg
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File comment: Completed, in 1x12 cab, with Reeves Vintage Purple speaker, rear view.
rear_full.jpg
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File comment: Rear panel removed to better see speaker, chassis, tubes and transformers.
rear_back_panel_removed.jpg
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File comment: Top of the chassis, detail. Loaded with 6V6 power tubes.
chassis_top_detail.jpg
chassis_top_detail.jpg [ 3.65 MiB | Viewed 287 times ]
File comment: Another birds-eye view of the chassis top (or bottom, depending on your perspective!)
chassis_top_tubes_xformers.jpg
chassis_top_tubes_xformers.jpg [ 3.33 MiB | Viewed 287 times ]
File comment: Full-on view of the all the guts. Completed!
guts_full.jpg
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File comment: Another gut shot, angled.
guts_angle_left.jpg
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File comment: Another angled gut shot.
guts_angle_right.jpg
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File comment: A different angle of the guts, with a better view of the inside of the rear panel.
guts_detail_rear_panel.jpg
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File comment: Gut shot angled to get a better view of the inside of the front panel.
guts_angle_front.jpg
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File comment: Inside of front panel, detail 1 of 2.
guts_detail_front_panel_partial_1.jpg
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File comment: Inside of front panel, detail 2 of 2.
guts_detail_front_panel_partial_2.jpg
guts_detail_front_panel_partial_2.jpg [ 5.81 MiB | Viewed 287 times ]


Last edited by matt_garman on Wed Nov 27, 2019 4:09 pm, edited 2 times in total.
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PostPosted: Wed Nov 20, 2019 3:54 pm 
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That's some heavy-duty shielded cable you used!

The wiring looks OK. As you said, just check several times to make sure everything is connected properly and there are no accidental shorts. Then follow the start-up procedures in the manual.

A good tip that has been mentioned lots of times is to make a copy of the layout drawing and use a highlighter pen to mark the wires and connections as you check them. On original Hiwatts, they used red ink to mark the actual connections as they did their checking. You don't have to go that far, though.

Looks like the secondary side of your output transformer is wired properly. There should be four wires - a black one going to the ground lugs on the speaker jacks and the green, yellow and orange ones going to the impedance selector switch. The primary could have five wires. The red one goes to B+, brown and blue go to the output tubes. The blue-white and brown-white are a different impedance winding on the primary. They aren't used, so just cap their ends with heat shrink tubing. You can coil them up out of the way or tie them to the brown and blue.


Last edited by mitch m on Wed Nov 20, 2019 6:08 pm, edited 1 time in total.

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PostPosted: Wed Nov 20, 2019 4:27 pm 
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mitch m wrote:
That's some heavy-duty shielded cable you used!


I forgot to mention that in my original post, that's Canare Star Quad Microphone Cable. That was recommended to me over on diyAudio. Only this year have I got back into guitar, before that I was doing hobby electronics for music playback (i.e. stereo speakers, DACs, amps). I've been using that Star Quad for all line-level connections for years now, and have quite a length of it. I think I spent over an hour just stripping and prepping it for the Triwatt! But as the audiophiles would say, using that is good for removing at least 10 veils from the sound. :roll:

That's really the only place I deviated from the Trinity-supplied parts. I did use my own Teflon-coated, silver wire (military spec) in a few places, just because I have a lot on hand. In particular, it was nice for making that bus bar on the turret board, and leaving me with long lengths of teflon insulation that I could re-use on a few spots where I thought it might be useful.

mitch m wrote:
Looks like the secondary side of your output transformer is wired properly. There should be four wires - a black one going to the ground lugs on the speaker jacks and the green, yellow and orange ones going to the impedance selector switch. The primary could have five wires. The red one goes to B+, brown and blue go to the output tubes. The blue-white and brown-white are a different impedance winding on the primary. They aren't used, so just cap their ends with heat shrink tubing. You can and coil them up out of the way or tie them to the brown and blue.


Thank you for that, in my original post I wrote "secondary" by mistake, when I meant "primary". I edited the post to fix that. So double-thanks, not only for the technical info, but for catching my typo. Can you see why I'm intent on multiple sanity checks before powering up? :)


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PostPosted: Wed Nov 20, 2019 6:11 pm 
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No problem. I knew what you meant. Good luck with the check out and mounting the amp in the cabinet. It should sound good with the Reeves Vintage Purple speaker.


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PostPosted: Sat Nov 23, 2019 4:20 pm 
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Did another eyeball check, then a final check, highlighting traces on the diagram as I checked them. Didn't find any mistakes.

Did the initial power on test (with no tubes), basic voltages looked correct. My B+ seemed a little low: 472 versus 490 as suggested by the documentation. (Mains voltage reads 122 VAC.)

So I went ahead and installed all the tubes. The preamp tubes look OK, but the power tubes started to red plate. I tried to check the bias voltage, and I was afraid to leave it on too long, so am not sure of my reading, as it seemed to jump around a bit. But I couldn't get anything under 100mA, which is way too high for 6V6 tubes. I tried the bias switch in both positions, and the adjustment pot in both extremes.

Clearly something is askew, anyone have any thoughts or suggestions on what I should try or test next?

Thanks!


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PostPosted: Sun Nov 24, 2019 1:52 am 
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Make sure all the resistors are the proper values in the bias circuitry for the output tubes. Did you check them with an ohmmeter before installing them? Sometimes brown, red and orange color bands on resistors can look similar.

With the output tubes removed can you measure the bias voltage and see it changing as you rotate the bias pot?

Was a speaker attached when you did the testing? Could be the amp is oscillating and you would hear it on the speaker. If so, reverse the connections from the output transformer to the anodes of the output tubes.


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PostPosted: Sun Nov 24, 2019 12:59 pm 
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mitch m wrote:
Make sure all the resistors are the proper values in the bias circuitry for the output tubes. Did you check them with an ohmmeter before installing them? Sometimes brown, red and orange color bands on resistors can look similar.


I did indeed use my DMM to check the resistor values before installing. I'm pretty confident I didn't make a mistake here, as I did at least three checks of each resistor before soldering in place. Just now, I also went through and re-checked all the color band coded resistors to make sure they are correct (i.e. I read the color codes, rather than using the DMM, since they are now all in-circuit).

mitch m wrote:
Was a speaker attached when you did the testing? Could be the amp is oscillating and you would hear it on the speaker. If so, reverse the connections from the output transformer to the anodes of the output tubes.


Yes, I did have a speaker attached. It was dead quiet when powered up. The documentation indicates this itself could be a problem, but I did get a little bit of hiss as I turned the master volume up. I would call this hiss "typical tube amp hiss", i.e. it was in line with my expectations.

mitch m wrote:
With the output tubes removed can you measure the bias voltage and see it changing as you rotate the bias pot?


I get zero volts when doing this. But with the tubes removed, isn't that expected? The bias test points go to tube pin 8, which is open with tubes not installed.

Looking at the schematic, it looks like I should see -54V and -45V on either side of R45 (15k). With the power tubes out, I get a much lower value (in magnitude), and it continually decreases, tends to trend towards -20V, or even -10V. Not sure what to expect with the tubes out though.

Thank you so much for the help and assistance!


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PostPosted: Sun Nov 24, 2019 4:18 pm 
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Yes, without the output tubes installed there should be 0 volts at the bias test points

But you should see about -54 volts at the junction of D6/R45/C22 and it should be steady.

At the junction of R45/R46/C23 the voltage should be closer to -45. It should vary with the setting of the bias pot, but once set it shouldn't tend to go towards 0.

If your multimeter checks diodes, make sure D6 is OK. Also make sure all the connections in the bias circuitry are good. Check them for continuity with the multimeter probes on the actual leads of the components, not the turrets.


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PostPosted: Sun Nov 24, 2019 4:47 pm 
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OK, some definite success. After staring at the layout diagram, schematic, and my work most of the day, I finally noticed something I've missed dozens of times: the jumper wire between R43 (180k) and R44 (620k) was missing. I soldered that in place, and now the tubes no longer red plate. My 6V6 tubes are at about 15mV bias right now. This is actually with the trim pot maxed out: the range seems to be about 9.5mV to 15.5mV. So now I'm a little on the low side, as the docs say 6V6 bias should be between 15 and 23 mV. So I would think I should be able to to a little higher. At least I don't run the risk of killing the tubes too quickly now.

I went ahead and plugged in a guitar and played a few notes. Didn't run through everything, but I quick tested the normal and bright inputs and overdrive. It plays music!

I'll probe around some more now, and see if any other readings are different than expected (besides the bias I mentioned above).

Thanks again!


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PostPosted: Sun Nov 24, 2019 5:34 pm 
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OK, here's the measurements I'm getting with 6V6 tubes and 122 VAC mains.

Notation: my measured value (documented reference value)

V1:
Pin 1: 147 (150)
Pin 3: 1.268 (1.2)
Pin 6: 132 (120)
Pin 8: 0.961 (1.0)

V2:
Pin 1: 192.4 (179)
Pin 3: 1.176 (1.2)
Pin 6: 112.2 (106)
Pin 8: 0.735 (0.7)


V3:
Pin 1: 277 (269)
Pin 2: 69.5 (67)
Pin 3: 73.5 (71)
Pin 6: 193.1 (188)
Pin 8: 1.534 (1.5)

V4:
Pin 1: 273 (274)
Pin 2: 73.1 (71)
Pin 3: 77.1 (74)
Pin 6: 283 (236)
Pin 7: 66.6 (64.4)
Pin 8: 77.1 (74)

V5:
Pin 3: 458 (441)
Pin 4: 426 (411)
Pin 5: -44 (-39)
Pin 6: -44.1
Pin 8: 15.7 mV

V6:
Pin 3: 460 (441)
Pin 4: 427 (411)
Pin 5: -43.8 (-39)
Pin 6: -44.0
Pin 8: 14.9 mV

At the D6/C22/R45 junction, I measure -58.8 (-54).

At the R45/C23/R46 junction, I measure -44.5 (-45).

On the big filter caps:
For the "top" or "outer" cap (C21): the "top" lead (closest to the edge of the chassis) measures 419 VDC. The "inner" lead measures 425 VDC.

For the "inner" cap (C20): both leads measure 458 VDC.

Some of those feel like they might be off more than they should be, but I don't have enough experience to know for sure.


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PostPosted: Mon Nov 25, 2019 1:40 am 
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Glad you found the problem. That little jumper is hard to see on the layout drawing. It would pretty much shut down the bias circuit if it's not there, though.

The voltages look good. Close enough to not indicate any problems.


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PostPosted: Mon Nov 25, 2019 2:52 pm 
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mitch m wrote:
Glad you found the problem. That little jumper is hard to see on the layout drawing. It would pretty much shut down the bias circuit if it's not there, though.


Thank you again for all your help! Whenever I do these kinds of projects, and things don't work, I worry it's something super subtle that I won't be able to fix. But in just about every case, it turns out to be something silly like this. I can't tell you how many times I checked that turret board when I initially assembled and built it. I even did the highlighter-on-every-trace thing. I went back and checked my notes, and sure enough, I didn't highlight that little connection!

I probably took a little life away from the power tubes. But ultimately I want to run KT-66 tubes anyway.

mitch m wrote:
The voltages look good. Close enough to not indicate any problems.


So you think it's OK that I can't set the 6V6 bias any higher?

Last night, I went ahead and mounted it in the chassis along with the Reeves Vintage Purple Speaker, and spent a little time playing through it last night. I had to keep it at "family friendly" levels (read: basically conversation volume), so I couldn't really get the true experience. But even at very low volume, what I heard was consistent with everyone else's positive comments. Looks like the two inputs, along with the tone controls allow pretty extensive tone sculpting. I didn't even play with the overdrive at all, nor did I play through the link channel. IOW, I barely scratched the surface of what it can do. But it's always nice to have initial testing be so encouraging!


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PostPosted: Tue Nov 26, 2019 4:13 am 
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You could try changing the 180K resistor in the bias circuit. If you want to run KT66 tubes the bias will probably be low for them too.

As an experiment, if you have a 1Meg resistor you could clip or tack-solder it in parallel with the 180K and see what that does. That will reduce the 180K down to about 150K so you should have more bias range.


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PostPosted: Wed Nov 27, 2019 5:08 pm 
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Note: I edited my first post to include several pictures of the completed build.

mitch m wrote:
You could try changing the 180K resistor in the bias circuit. If you want to run KT66 tubes the bias will probably be low for them too.

As an experiment, if you have a 1Meg resistor you could clip or tack-solder it in parallel with the 180K and see what that does. That will reduce the 180K down to about 150K so you should have more bias range.


Thanks again! I was thinking of something similar (i.e. reduce the value of that resistor) for getting the bias a little hotter, glad to see my basic understanding of the circuit is correct!

I'm trying to think of any other components I might want to order when I pick up a 1M. Maybe some extra resistors and caps to have handy in case I ever want to do the suggested mods/tone tweaks. Any other suggestions?

I still haven't had a chance to crank it up to "impolite" volumes. But still more time to play with it in general. For having a relatively small number of controls, i.e., being a fairly simple amp, I feel like the tonal palette is very broad. That is, the different inputs (with independent volume control), overdrive and tone controls really allow a tremendous amount of useful tweaking. Now the "problem" is finding which sound I like best. Haven't heard anything bad yet; just too many flavors to pick a favorite.

What I've been using is a Ceri@tone Dizzy30 (Matchless SC-30 clone, loaded with a WGS Retro 30). I have an A-B switch that I was using today to go back and forth between the Triwatt and the Ceri@tone, on the EF86 channel. Again, both were at low/"family friendly" volumes. But even at low volumes, it's interesting to hear the difference between the two. I now see why people call Hiwatt style amps "punchy": with a moderate or stronger pick attack, the Triwatt has an almost percussive sound on the initial note attack. The Dizzy30 sounds almost compressed by comparison, as the initial note sound is more "rounded".

I've also heard people refer to Hiwatt-style amps as "hi fi" sounding. I can see that here too, as the Triwatt to me sounds very precise. I hate to say clinical, because that often comes across as a negative. But I look at it as being more "pure", letting more of the tone and timbre of the guitar shine through. Perhaps "transparent" is the word I'm looking for. Whereas, in contrast, I feel like the Dizzy30 imparts more "amp character" into the tone.

I didn't really spend any time comparing the Triwatt to the 12ax7 side of the Dizzy30. That was deliberate, as the EF86 side seems to have a lot more character and interesting tone, even at low volumes. Just guessing, but I suspect the 12ax7 side wouldn't be quite as different compared to the Triwatt. And anyway, I feel like at these lower volumes, I think most 15W or greater tube amps lose a lot of their character.

Having both the Ceri@tone and the Triwatt running at the same time sounded fantastic!

I have a fairly small pedal board, that I basically use for a handful of different dirt tones. The stack looks like this, starting with the closest-to-guitar side:
  • Tuner
  • Large Beaver (DIY Big Muff Pi clone)
  • Aion Andromeda (DIY Nobels ODR-1)
  • Strymon Lex (Leslie rotating speaker simulator)
  • Silver Pony (DIY Klone Centaur clone, used as a volume boost)

I never had any complaints with those pedals and the Dizzy30. However, I do think the Triwatt better "integrates" the pedals into the overall tone. That could just be expectation bias, as the Triwatt (Hiwatt in general) is so well known as a pedal platform (and indeed, one of the reasons I wanted it). Either way, my high expectations are so far met on the works-with-pedals aspect. (That Strymon Lex is a great rotating speaker sim. It has mono and stereo outputs. This is the first time I've been able to use it in stereo mode with two amps---that's where it's at! If you have any interest in a rotating speaker effect, it's worth the effort to run in stereo.)

Overall, I'm super happy with it. I wish I'd had the patience to make it a little neater, but I think it's good enough. This was my first time assembling something like this. I've done a fair amount of diyAudio, but usually I have the overwhelming majority of components on circuit boards. And then the wiring is very simple wires from one PCB to another, and to (typically very minimal) I/O on the chassis. E.g., my power amps just have speaker outs, line level in, power IEC, and a power-on LED. So it's a lot easier to keep things neat and tidy. Next time I build a tube guitar amp (already have my eye on the TC15), I think the main thing I'll do is solder the wire leads to the turret board before I mount it. And I might invest in one of those wire bending tools. This is one of those projects that seemed overwhelming at first, and now looking back on it, it doesn't seem all that bad.

Oh by the way...

mitch m wrote:
The primary could have five wires. The red one goes to B+, brown and blue go to the output tubes. The blue-white and brown-white are a different impedance winding on the primary. They aren't used, so just cap their ends with heat shrink tubing. You can coil them up out of the way or tie them to the brown and blue.


The striped primary wires are indeed a different impedance winding. In particular, they are for running EL-34 tubes. That info came from Stephen directly (via email).


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PostPosted: Thu Nov 28, 2019 1:10 am 
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Sounds like you are having lots of fun with the Triwatt! Congratulations on a successful build.

The pictures look great. The cabinet looks very authentic with that tolex and grill cloth.

I built a couple of Hiwatt clones a few years ago - a very authentic reproduction of a 50-watt DR504 with EL34 tubes, and a 30-watt version with 6V6 tubes something like the Triwatt. They have lots of clean headroom and can sound very "precise" as you said. But to really get the full effect you have to crank them up! I thought they sounded good, then one day a guitar player a lot better me played my 504. We cranked it and it sounded fantastic! It was a totally different amp compared to how it sounded with me playing at "polite" levels. So with these amps, volume and playing style play a big part in their tone.

Here's a picture of the chassis for my 504.

Attachment:
Custom 50 076.jpg
Custom 50 076.jpg [ 63.16 KiB | Viewed 282 times ]


I have a Large Beaver and a Silver Pony too, and they work well with my "Hiwatts."

It's good to have an assortment of the common values for resistors and capacitors on hand. You can start with the parts for the mods suggested in the manual.


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PostPosted: Sun Dec 01, 2019 12:32 pm 
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Congrats on the successful build.

For the bias, make sure your switch is set to 6V6 position (lower B+ & Bias voltage position incorporating the Zener diode and 180K bias resistor, and the correct bias resistor. If it is still low, you can make the voltage MORE negative by adjusting that resistor to say 150K. Just Remember that the KT66 position puts the two (180K//620K == 140K) in parallel to obtain a higher bias voltage.

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PostPosted: Fri Dec 06, 2019 5:36 pm 
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mitch m wrote:
Sounds like you are having lots of fun with the Triwatt! Congratulations on a successful build.

The pictures look great. The cabinet looks very authentic with that tolex and grill cloth.


Thank you! And thanks again for your help with the build and troubleshooting.

All the credit for the cabinet goes to Trinity though, they built it for me.


mitch m wrote:
But to really get the full effect you have to crank them up! I thought they sounded good, then one day a guitar player a lot better me played my 504. We cranked it and it sounded fantastic! It was a totally different amp compared to how it sounded with me playing at "polite" levels. So with these amps, volume and playing style play a big part in their tone.


Isn't that true for pretty much all tube amps? :)

So far, I find the Triwatt's master volume to be quite usable. I agree louder == better, but when I don't have that option (most of the time), I like to have more than a micrometer of usable volume knob control (which is kind of how the Dizzy30 is).


mitch m wrote:
Here's a picture of the chassis for my 504.


Wow, that is impeccable! I take it that wasn't your first build? I feel like next time I build a tube amp like this, I'll be able to do much cleaner work.


mitch m wrote:
It's good to have an assortment of the common values for resistors and capacitors on hand. You can start with the parts for the mods suggested in the manual.


I agree, I do already have a decent collection of common (and not-so-common) parts. But a lot of it is surface-mount, and even the through-hole stuff is generally physically small and/or low-wattage. The whole "schema" of common parts somewhat changes when one goes from working on dense, low(er) voltage PCB circuits to these tube circuits.

Anyway, as for the components to buy, looking page 59 of the Triwatt Builder's Guide, under "Tone Tweaking":
Quote:
V1 Pin 8 -Townshend/Who CP103 1k5 + 64uF
V1 Pin 8 -Jimmy Page amp 2k2 + 100uF with additional parallel 1k5 resistor
V1 Pin 8 -SAP DR 103 2k2 + 100uF (no additional resistor)
V1 Pin 8 -Late '70s, Late '80s and OL/Lead 1k5 + 150uF


First question: those are pretty big cap values. Getting film caps that big (at least through Mouser) is really expensive. Can electrolytics be used here? Should the caps be rated for the full plate voltage (plus some additional safety margin)?

Next, just to make sure I read those right: pin8 is the cathode of one of the triodes within the 12ax7. So these mods are tweaking the cathode resistor and/or cathode bypass cap. The stock is no cap and a single 1k5 resistor. Are all the above in addition to the 1k5, or in place of the stock cathode resistor?

And for the one mod, "Jimmy Page amp 2k2 + 100uF with additional parallel 1k5 resistor" - does that mean all three components are in parallel, i.e. 2k2 // 1k5 // 100uF? And one could (in theory) use an 890R in place of the 2k2//1k5?


coco wrote:
For the bias, make sure your switch is set to 6V6 position (lower B+ & Bias voltage position incorporating the Zener diode and 180K bias resistor, and the correct bias resistor. If it is still low, you can make the voltage MORE negative by adjusting that resistor to say 150K. Just Remember that the KT66 position puts the two (180K//620K == 140K) in parallel to obtain a higher bias voltage.


Thanks! That's essentially the same suggestion Mitch M made above. I think I'm going get a few resistors (1M, 680K, 620K) and try them one at a time in parallel with the 180k, see where that puts the bias voltages.

A suggestion for documentation improvement: you list typical voltages at numerous test points, which is very helpful. But for each of those numbers, I'd also like to see a tolerance (like min/max or percentage). This would be useful for people like myself who don't have a good intuition how much leeway is available in the voltages.

For example, in my readings, V4 pin6 reads 283v, versus 236v suggested by the docs. That's almost 50v difference (about 20%). Is that OK?


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PostPosted: Fri Dec 06, 2019 8:24 pm 
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The voltage at the cathodes of the preamp tubes is very low, around 1 or 2 volts. So electrolytic capacitors rated at 50 volts would be suitable.

The way I read it, the mods suggested specify what goes on the cathode of V1.

V1 Pin 8 -Townshend/Who CP103 1k5 + 64uF
This looks like it's the existing 1k5 plus a new 64uf in parallel.

V1 Pin 8 -Jimmy Page amp 2k2 + 100uF with additional parallel 1k5 resistor
This looks like it's the existing 1k5 plus a new 2k2 and a 100uF all in parallel. You could use an 890-ohm resistor, but that's not a standard value and even if you got one it would be harder to go back to the original configuration if you don't like the mod.

V1 Pin 8 -SAP DR 103 2k2 + 100uF (no additional resistor)
This looks like the 2k2 replaces the 1k5 and there's a parallel 100uF.

V1 Pin 8 -Late '70s, Late '80s and OL/Lead 1k5 + 150uF
This looks like it's the existing 1k5 plus a parallel 150uF.

The rule of thumb with tube amps is the voltage can vary + or - 10%. If it's 20% over at V4 pin 6 that's starting to get on the high side. The voltage at pin 1 of V4 is good so it's just variance with the tube and not a problem with your circuit. You could try a different 12AT7 there if it bothers you, but the higher voltage isn't exceeding the tube's specs so if it sounds good I wouldn't worry about it.

Thanks for the compliment about my DR504. It was actually my second tube amp project. The first one was a Trinity TC-15 I built about a year earlier, but I had been building electronic projects for over 30 years by that time. The assembly work for the original Hiwatt amps was contracted out to an outfit in England that also did work for the British Navy. The wiring was very neat and close to military specifications. I tried to emulate that as closely as possible when I built mine. Also I started with a fairly big chassis, like the originals had, so it was easier to keep the wiring from looking cluttered.

Here's a picture of the outside of the chassis.
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PostPosted: Sat Dec 07, 2019 12:13 am 
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Location: Shawnee, OK
Mitch, did you loom the wiring on the mains and power transformer wiring or are those cable ties? Curious minds (mine) would like to know :hmmm: . In any case, sure is "priddy" (Okie for pretty).

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PostPosted: Sat Dec 07, 2019 1:30 am 
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Posts: 398
Location: Qualicum Beach, BC
Thanks, Hank. The original Hiwatts used cable lacing and plastic tubing to bundle the power and transformer wires, so I did that too. Also like the originals, I attached all the fly-off wires to the underside of the circuit board. It sort of looks like the board isn't wired to anything yet in the photo of the chassis interior I posted earlier, but that's the completed amp.

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I'm happy to answer your questions, but this is sort of hijacking Matt's post about his successful Triwatt build. I have lots more pictures of my DR504 project and I can post some of them in the Dressing Room section if anyone is interested in seeing what a Triwatt's big brother looks like.


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