Hi, Masters of Trainwrecks,
I want to build up (now) the Liverpool.
Only question is the PT. As there is always a discussion with high voltage trannys for the Express it seems for me that for the Liverpool is a PT with around 250 AC /0,12 A enough (plus 4A for the heater).
Right?
Because thats what I have on my desk
The OT is a Hammond 125E where I can choose my Raa. Quite enough too. What you mean?
Btw: the high value irons will get my new Concorde Clone
I think you will find that both the PT and OT you are considering are undersized. For the best results, you should use a PT that can deliver at least 250mA, and 300mA would be even better. And the 125 E is definitely too small for a Liverpool. You should be using an OT that is spec'd for between 30 and 50 watts. The 125E is a 15 watt OT.
You might get by with that iron if you build half of a Liverpool - in other words, using only 2 EL84's.
fwiw - Yes I tend to agree with the gurus. One common element in all the Trainwreck builds was the use of oversized iron. There are many reasons for that if you're after Trainwreck tone.
I was afraid you will answer something like that.
When I count all the current for the PT - I´m right there. But there is the fence. Thats throuth.
I was mor afraid bout the OT. your mentioned 15 Watt are right, but I thought thats for clean. This OT is able to handle over 30 Watt overdriven! (RMS?) And sounds still not bad, I tried it with 2xEL34.
But for shure you are right, because, as I understand K.F., its nesessary to use oversized irons.
I should`nt ask
Now I have to find bigger one for shure to sleep well.
Best
Hans-Jörg
Edit:
Because I have not the cash for the moment for new bigger irons (there is a Concorde waiting too) I´ll build it up withe mentioned irons and 2 tubes. But there will be 4 sockets. In one ore two months, after concorde, I´ll buy bigger irons. fill the empty holes and change the iron only. Thats the best way for the moment - and Christmas time
Hi Gents,
I got now a offer for a OT and PT wich I cannot ignor. Both from the Engl 601 Jive wich is a very conservativ 30watter with 2 EL34 normaly and 4 ecc83. There is the Voltage around 320 AC. Instaed of the orig. 260VAC.
Is this a problem? and how to handle if I have to go down at least 50 Volt more to stay aprox. in the Liverpool specs?
Shall I keep the resistor rail down with the 1k,18k2,9k1,9k1,9k1?
This Engl iron is still not really ideal, however, it might work out OK. The 601 is an EL34 based amp, and so the primary impendence will most likely be much lower than 5.2K, which is generally considered the standard for a Liverpool. The 320V PT, as you noticed, is a bit high, and you will have to use zeners, dropping resistors, a VVR, or some other means to lower the voltage.
If you really want a Liverpool that sounds like a Liverpool, you should consider buyng the proper iron for the build. Transformers (and tubes) are probably the most important components to get right when you copy another amp. A proper set of Liverpool trannies can be purchased from RJ, here on this forum. He is a great guy, very knowledgeable, and carries a nice line of transformers including a few choices that would be suitable for a Liverpool. I suspect that it will cost you somewhere around $200 for the PT and OT combined, and you will get great iron that is appropriate for this amp. That, and a really nice set of tubes will probably take you 90% of the way to a killer amp.
If you do decide to use the Engl iron, the solution I would use for the voltage is a VVR. I would want one on the amp anyway as these amps can get pretty loud pretty fast. And if you configure the VVR just right, you can set up your maximum voltage right where you need it to be. Let the MOSFET do the work for you.
Thanks for your all replay,
and VVR is one point what I wanted to, but more in the way to reduce the heater voltage of the power tubes. But in this case (for the next months is no chance for propper - more original - irons from whom ever -my first choice is RJ, but States/Austria is not ease to handle, lets see)
Ireflect for the complete VVR. So: do someone has a schem for a build? I know its easy, but I have no idea how to build. In the net I find only ready built ones.
A schem would help me much to build i t by myself.
And when the great day comes I can swap the irons easily.
Are you running a 240V tranny at 230? I know some of those spots have that as standard. If you want to hit one dead on I can Edcor to wind us a power tranny for a specific mains voltage. It doesn't cost a lot extra since they have already engineered the 120 and 240 volt versions.
Shipping to anywhere in the world is cheapest using the flat-rate boxes US postal system. There is a 20 pound limit which is good enough for a set of transformers and costs under $50. They have also recently come out with a flat rate box that is just about right for shipping chassis. The combo of these two boxes can get you an entire amp package delivered for under $100 US. However my thought is that this is only a good option if there isn't a manufacturer in your part of the world that can supply or build to your specs.
For most Trainwreck amps if you look at the VOX AC-30 replacement power transformers, the voltages are pretty close and they are certainly beefy enough. These should have taps for all the Euro voltages and you should be able to find those on your side of the pond.
about the price thats a fact. Here (Germany/swiss/Austria) the prices for Iron is quite high. Especialy replacements. But winding is an option!
I buy the most amp stuff with " Tube-Town" Germany.
However, I´ll build it up with the Engl 601 trannies. When the time comes and I´ll find the right iron, I´ll change them. But I have to reduce the voltage aprox 90 V.
Again: hows about a VVR schem?
The heater I wanted to reduce for same reason: to come to bed room level without a lost of tone. It works very well (power tube heaters).
But if I put in the VVR its no more nessesary.
Reducing the power tube heaters is very bad for the power tubes. I believe the problem caused is called Cathode Stripping. The rule of thumb I have been taught is to always keep the heaters at their proper voltage (6.3V typically), and only play around with the plate voltages.
As for the VVR schematic, the maker of the VVR is one of the members here. You could contact him about a schematic I suppose. But since he sells the boards, he might not be that interested in sharing the schematic On the other hand, the board is tiny, and inexpensive, so buying one and shipping it to you will not cost a lot. Most of us here like to support the members of this forum (as a way of keeping this community so wonderful) by buying their products when it is practical. So I encourage you to contact Dana Hall, and purchase his VVR. It is a great product, and Dana is great to deal with.
On the other hand, the board is tiny, and inexpensive, so buying one and shipping it to you will not cost a lot. Most of us here like to support the members of this forum (as a way of keeping this community so wonderful) by buying their products when it is practical. So I encourage you to contact Dana Hall, and purchase his VVR. It is a great product, and Dana is great to deal with.