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millerlitescott 12th March 2010 10:03 PM

Simple P P build cost
I hope this will be my first tube amp build. I have limited experience in modding crossovers and playing around with SS amps. I would like to build a good amp not the cheapest not the most expensive and I am thinking on just going for the EL34.

It appears that the transformers are the biggest expense and I do not know anything about the Transformers and I am going to rely on everyones input as to what transformers work best at a reasonable price point.

Thanks for any input.


rknize 12th March 2010 11:44 PM

What is your price point?

millerlitescott 12th March 2010 11:48 PM

I am not sure yet. I am hoping sub $400.00 USD. I think it is going to depend on the iron.


nic6paul 12th March 2010 11:55 PM

I assume you mean El84?

The 6CW5 PP would be a bit cheaper if you wanted to go that route. Those tubes run around $5 each compared to the El84s run around $10 each. You would also not need to purchase a rectifier tube and the power transformer should be a bit cheaper too. Just something to think about if you are really looking to go the cheaper route.

millerlitescott 13th March 2010 12:21 AM

I guess I am trying to find out the cost of each route so I can decide if I need to got the cheaper route or not.

And yes I did mean EL84.


rknize 13th March 2010 12:29 AM

$400 total or for the OPTs? Figure about $100 for a pair Edcors, which are a very solid OPT for that price point. There is always Hammond for more $$ but not necessarily more performance.

millerlitescott 13th March 2010 01:00 AM

$400 Total. Working amp less chassis. I will build that from stuff i have laying around.

I guess I would like to see a spread sheet type set up with different output tubes and Transformers and approximate cost for each variant in a general sense.

EL 84 Transformers# Cost 6CW5 Transformers# Cost




I am a newbee just trying to learn and at this stage all the different transformer # and voltage rating for this and that make my head spin.
I think I just need a starting point to start understanding everything and I can take it from there. I am greenhorn in the tube amp building arena.


nic6paul 13th March 2010 01:16 AM

Well the component cost will be almost identical if you go with the el84 amp or the 6cw5 with the exception of some diodes otherwise the cost there should be the same.

The power transformer for the 6cw5 is $30 plus I think it was $10 shipping from

Output transformers would be $47.13 each from edcor plus shipping. You would have to find out which would be the prefered transformer but I think the CXPP25-16-7.6K would work with an 8ohm load. I could be wrong.

Ian444 13th March 2010 04:30 AM

For the EL84 build...
Scott, you should be able to do it for under $400. So far, for an EL84 version with tube rectifier, this is what I can work out. For a 6CW5/EL86 build, the tranny choices here do not apply.

PCB, $43. Parts for PCB, around $100 or less, including sockets and 5AR4 rectifier tube. Less if you use parts from your stash.

Possible power tranny choices:
Edcor XPWR131, 120Vrms, 60Hz. 660V(330-260-0-260-330)@175mA, 6.3V@4A & 5V@3A, $61.89 USD
Edcor XPWR008, 120Vrms, 60Hz. 600V(300-0-300)@200mA, 6.3V@4A & 5V@3A, $53.77 USD
Edcor XPWR066, 240Vrms, 50/60Hz. 600V(300-0-300)@200mA, 6.3V@4A & 5V@3A, $63.36 USD
Hammond 372HX, universal primary, 300-0-300@230mA, 6.3V@6A, 5V@3A, USD$120
Hammond 372FX, universal primary, 300-0-300 @ 173mA, 6.3V@5A, 5V@3A, USD$105 AES, USD$83 Triode Elec.
Magnetic Components, 2 x 120V primary, 355-305-0-305-355@200mA, 6.3V@5A, 5V@3A. Triode Elec P/N 40-18029 for Fender Twin guitar amp, USD$80.
Antek 2T300, 2 x 115V primary. 2 x 300V@300mA, 2 x 6.3V@4A, $35 USD. No rectifier winding, but maybe we can fix this, read below.

Possible output tranny choices:
Edcor CXPP25-MS-7.6K, 4-8-16 ohm taps, $57, or USD$47 for a single output tap. 5.25lb.
Dynaclone Z565, 8K primary, 4-8 ohm taps, $79. 4lb.
Electraprint, 7K6 primary, UL taps, max DC 40mA, 20W, 4-8 ohms secondary, USD$95.
Hoping Bud from O'netics will come back with a quote next week.
There's also Hashimoto HWC-30-8 30W for $180 each, or Silk P-60-15A 15W for approx $100 (but George recommends 20-50W). I would love to spring for the Hashi but it sort of destroys the budget.

Have a read of Georges tubes and transformers pages here, this is what we should be going by to make the decisions.

So with Edcor $47 output trannies and Edcor power tranny (say $60) we are up to around $300, so there is still room to move, but we are not there yet, and no shipping has been included. I have no idea of internal USA shipping costs. If you need to buy EL84 tubes I think a matched quad of JJ EL84 is around $60 or less, I have heard nothing but good things about these tubes and the guitar guys testify they can handle 350V to 400V reliably. Plus George put a set through the torture rack and they started glowing a bit at 420V.

This hypothetical $300 does not include: IEC inlet, power cord, fuse, power switch, RCA sockets, banana sockets, EL84 tubes, chassis or volume pot. This stuff can add up and the stash box comes in handy to reduce costs. There may be other stuff I've missed. I will be using some Russian 6P14P as I already have some, they are cheap and plentiful. If the B+ is too hot for them, I'm thinking of lowering the screen grid voltage to make them comfortable, or get some JJ EL84.

There's many ways to go about this. This is also my first build and man its agony making these decisions on iron. Keep in mind these examples of iron are simply what I have been looking at and is by no means what someone else may call a good choice. I am not ready to pull the trigger on any iron yet, but have all the rest on the way.

I am thinking of using the Antek 2T300 power tranny and modifying one of the 6.3V windings for 5V or make a new winding for 5V for the rectifier. I am not sure if this is a good choice. George recommends a 320-0-320 tranny. So proly best to find one like that. It's early days and we will find out more as the beta builders complete their building/testing/fine tuning.


Ian444 13th March 2010 05:07 AM

1 Attachment(s)
A simple spreadsheet to run with...

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