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PostPosted: Sat Nov 06, 2010 10:52 am 
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Holy Ghost
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I dont think the OT would go that high but I have not tested it. The PT does not have the secondary taps, but you could add a VRM to do that!

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PostPosted: Sat Nov 06, 2010 8:24 pm 
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Could you direct me to the schematic for the VRM circuit? I did a forum search but only found references to people adding it, not the circuit itself.

And it's not the "high end" of the 30-30k frequency range I'm worried about. It's more the handling of extended bass frequencies. The only transformers I found that went below 70Hz just happened to be 30Hz-30kHz.

Edit: Nevermind, I did a little further digging and I found a great layout and pictures of the VRM! I love this place!


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PostPosted: Thu Feb 17, 2011 11:21 am 
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I'm looking forward to building this amp. What are the pot values?


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PostPosted: Thu Mar 10, 2011 7:12 pm 
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Any chance we may see a Trinity hot rodded Tiny Terror kit in the near future?


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PostPosted: Tue Mar 29, 2011 10:34 am 
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Any chance that someone is still around that can email the big file?


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PostPosted: Tue Mar 29, 2011 4:40 pm 
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layout is posted.

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PostPosted: Wed Jul 27, 2011 12:26 am 
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Bill Jarrett wrote:
Do you know if your transformers will operate in the 30-30k ranges..

What do you mean by that??

Bill Jarrett wrote:
Does it have the additional secondary tap for the 15/7 watt ability?

No but, Trinity would recommend you use a VRM instead, so you can scale the power level to whatever you want with just a handful of components.

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PostPosted: Sun Dec 23, 2012 4:41 am 
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I found schematics and layout on this site, but I don't find the exact part list
For the capacitors , I don't know which sort I must buy (electrolitik, ....)
If someone have a part list , it will be great !!!

Franck


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PostPosted: Sun Dec 23, 2012 11:22 am 
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1uf & up are electrolytic axial 400 or more volts on power supply; 25V on cathodes. Rest are polyester 400V or more

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PostPosted: Fri Oct 25, 2013 6:12 pm 
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Hi Guys,

I plan to build my OTT Clone and I have questions about transformers.

Can I use this PT with 275V - 190V - 160mA secondaries without any components values modifications (Tiny_Terror_Layout_v.1.11) ? I ask this because I saw from another forum that :

Your transformer must be:
- primary: 240V
- secondary1: 250V 125mA
- secondary2: 180V 125mA
- secondary3: 6.3V 3A

For the OT, can I use this one?

Thanks for your help.
Huuubert


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PostPosted: Sun Oct 27, 2013 10:08 pm 
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Haven't built this amp so can't comment on it.

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 Post subject: Re:
PostPosted: Mon Dec 31, 2018 1:32 pm 
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The amp is actually biased at over 15W per tube static. It's insane. I swapped the 100 ohm cathode resistor for a 180 ohm, made no difference in the sound but made the tubes a lot happier.

It selects a different HV tap on the PT secondary. One leg remains tied to one side of the bridge rectifier, the other side has two taps and the switch selects between them. The result is something like 250VDC rather than about 325VDC.

It affects the entire amp, not just the power tubes, and it does NOT do anything to the bias state - so, in stock form the amp is severely (IMO) underbiased in 15W mode, and just about right in 7W. But I think the low voltages affect the feel in a negative way.

I replaced the power switch with a DPDT and also switched a second cathode resistor in parallel when I selected 7W. That made both modes idle happily.
You're right, I omitted the master from my drawing. It's a 500K dual-pot post-PI master with an extra set of .1uF caps.

The power switch is on my drawing, it's on the HV secondary. It selects between two 'ends' of the winding - HV winds up with about 325V and LV about 250V.
I don't know how you'd affect only the voltage in the power amp since the switch selects a different HV tap on the power transformer.

180 ohms is a good choice at 15W power; I replaced the power select switch in mine with a DPDT (Mouser sells the same switch brand and family) and used the other pole to place a 100 ohm resistor in parallel with the 180 when I went down in power. Worked great.

I don't think there's much to gain with cap swaps, myself. And both of my transformers were crooked too!







....this time about the half power switch. I know how it works an all as i've read the schematic but has anyone with the amp noticed a discernable change in tone and gain when switching between half power and full power?

I ask this as theres a rather interesting mod someone has suggested which allows you to change the bias of the Tiny Terror when switching between the power levels.

Basically you change out the current cathode resistor (120 ohms) to a 180 ohms cathode resistor which runs the EL84s less hot on full power mode and change the power swtich to a double pole version. One pole handles the power switch while the other pole can bring in a 100Ohm resistor in parallel with the 180ohm cathode resistor. That way you have a consistent bias level between the different power levels. That mod would be simple for a tech to fit.


I'm a bit confused about this set up. I'm considering a TT build but might add this mod right off the hop. Has anyone here tried this mod out to adjust the bias for the different wattage settings? Would it be too much to ask for someone in the know to draw up a little layout/schematic of the setup for this? Thanks!


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PostPosted: Tue Jan 01, 2019 11:28 am 
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It is similar in concept to the Tramp bias switch here:

http://www.trinityamps.com/docs/TrampSchematic18.pdf

Just modify the cathode resistors to suit.

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PostPosted: Tue Jan 01, 2019 10:20 pm 
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Thanks Stephen. I get it now. I had a small brain fart. I was a bit confused why people were switching out the "power" switch with a DPDT but I was taking that to mean the "on/off" switch but I see now it's the power level selector switch they are talking about just to add the extra resistor in. I was thinking there was something strange going on but now I realize it's pretty straight forward. I saw in another forum that somebody had rigged up this mod but preferred the amp in it's stock set up. I wonder if anyone here has tried it out and could share there thoughts? I am getting a pair of transformers out of a TT because a guy upgraded his with mercury magnetic transformers, so I think all in I can build the TT head for about $200. It's going to be a bit more of a learning curve than the Tramp kit was for me since I don't have good instructions to work from, but I'm up for the challenge. It's going to take me some time to finalize my grocery list of components...


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PostPosted: Tue Jan 01, 2019 11:21 pm 
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A VRM might be a better solution here!

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PostPosted: Thu Jan 03, 2019 1:22 pm 
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Yeah a VRM would be better to be able to volume down the amp once the amp is biased the way you like. It would even be more versatile than the 7/15 watt options. Any insight Stephen as to why amp makers would do a split transformer for different wattages over adding a VRM?


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