2x EL84 Liverpool

[Tabula Rasa]

Hi,

I registred a while ago and have read as many as possible threads to prepare myself for building a Trainwreck Liverpool with two EL84 tubes.

I have a little experience in building amps. (a Champ II clone, some sort of 5 watt SE marshall-like amp and the amp in the attachment.

I have a question about the transformers for the Liverpool. Some stuff you have in the USA is too expensive over here because of the shippingcosts.

I was thinking of using a Hammond 370HX as a Power Transformer. That one should work fine.

But i'm not shure about the output transofmer. I have a Marshall 18W type of OT here. It is 8 K primairy but I've read that Ken Fisher used OT's with a 5.2K primairy on the Liverpool amps, so a OT for a 2 EL84 should be 10.4K

can i use a Hammond 1609?

http://www.jukebox-revival.eu/media/pdf ... nd1600.pdf

[dave g]

I guess I'd go with the 1650F, but the 1609 would probably be okay.

Primary impedance isn't really a big deal as long as you're in the ballpark. Speakers are wildly reactive loads whose impedance varies quite a bit with frequency, so your output tubes aren't going to see a nice, constant 10k load regardless of what transformer you use.

[Tabula Rasa]

I guess I'd go with the 1650F, but the 1609 would probably be okay.

Huh? That one is 7.6K, that is not even near the 10.4K i'm looking for. Why the 1650F?

[didit]

I'm on a similar project and 1609 was my output transformer choice. It's as close to half a 5k2 as I could find. For power I settled on a 370DAZ. Anticipating some regret and eventually a swap to something a bit bigger. I wanted Z mount and from past experience with Hammond 300 series I know they are conservatively spec'ed. The parts are boxed awaiting time in my busy life to do the build.

My sums on required current came to just over 110mA. A 370EX should be ample. 370FX is perhaps fine too. The 370HX is just way overkill.

The 1650F is designed for a pair of el34 or 6v6.

Best .. Ian

[JoeCon]

On the 2 EL84 Rocket I built I used an 8K 25 watt Edcor OT.
Sounds great...
If I was building a Liverpool version I'd use the 8K again...

[didit]

For Rocket-style an 8k makes sense. I'd start with one of RJ's Edcor or perhaps a Z565. Liverpool is a different beast and a larger Zaa is going to get closer.

Best .. Ian

[JoeCon]

Ian

That 8k sounds nice too. Check out RJs non trad Liverpool post and hear his amp with an Edcor.

Enjoy!

[Tabula Rasa]

I have a 18 watt 8k OT, but i realy want a 10k OT. Edcor isn't very easy to get here in the Netherlands and i'm on a budget. Max 125 us dollar / 100 euros.

[didit]

Both the Edcor and Hammond are hifi by design and an Marshall 18W isn't. There has been and will inevitably be endless discussion about sublte differences between various output transformer choices. A hifi design is a 'wreck foundational principle. Wish I could give first hand experience on how well these work. In a month or so I will. Looking quickly at the jukebox revival site the 1609 and 370EX are listed. Pricing is a bit higher than Angela and others in NA but not too bad. You might want to check in with RJ and find out what it would cost for a set of his 15W Edcor, but expect it's easier and cheaper to order locally.

Best .. Ian

[Tabula Rasa]

& didit: thanks for your input. I think i'll go with the Hammond 370hx or fx and the 1609. I tbhought the 1609 would be a little to small with its 10 watts RMS, but it's a audio OT, so in a 15 watt guitar amp IT could just do fine.

jukebox-revival is a local onlineshop bthat is a little bit cheaper than other local shops and they have a very good service . Never had any problems.

i can't wait to start building the Liverpool. Would be great to have a more gainy amp next to the amp in the OP. One for clean and one for gain. If the Liverpool cleans up good enough with the guitars volumepot, i might just use that one on its own.

[didit]

I suspect you'll find it satisfies. Would be interested in hearing about results.

Unless you're looking to perhaps recycle in a bigger amp the HX is just added cost & weight. The pair of EL84s and three ecc83s are worst case 2.75A for filament and depending on biasing the HT is between 90-115mA.

[overtone]

Tabula Rasa,
if you really want a 10k in Europe then maybe Don Audio in Spain is your answer. He seems to have the Edcor CXPP30-MS-10k in stock right now. That one is rated 30w and is well inside your budget.
Best, tony

[Tabula Rasa]

Thats perfect. Great!

[Tabula Rasa]

Tabula Rasa,
if you really want a 10k in Europe then maybe Don Audio in Spain is your answer. He seems to have the Edcor CXPP30-MS-10k in stock right now. That one is rated 30w and is well inside your budget.
Best, tony

Overtone: Thanks!!!! That was a good advice. Now i'll try to find the right PT. Probably the Hammond 370FX.

[M Fowler]

It's odd that Don's Audio won't have the PT to go with that Edcor OT.

Only need 120 to 150mA for an 18w and since the circuit is diode rectified you don't have to worry about 5v tap.