Simple P P build cost

[rknize]

Originally Posted by Ian444

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.

I have a quad of Sovtek EL84Ms, which are 6P14P-EVs and can supposedly take more plate voltage and have longer life than the regular 6P14P. They don't like more than about 310V across them and start to glow around 320V, which is about what you will get with a 650VCT transformer. I was able to get them up to 330V by lowering the screen voltage to around 250V, but this had a very noticeable effect on the distortion spectra. The higher-order harmonics became much more apparent.

I recently got a quad of JJs and they can take it. Very nice spectra too. In fact, I had trouble with one of the Sovteks and talked to Brian at TubeDepot.com about EL84 choices. As you might suspect, all of the New Sensor EL84s are slightly modified 6P14Ps and none of them can really take these bent operating conditions well. He more or less said that JJs are the best and they are the cheapest to boot.

Not saying the New Sensor EL84s are bad tubes. They just won't like having more than 300V across them, so choose your power transformer accordingly. 600VCT should keep your Sovteks happy.

[Ian444]

I have some NOS Reflector 6P14P-EV from 1986. Thanks for the heads up on different distortion characteristics with lowered screen voltage, if I use the Antek with 600V CT I should be OK. There will be less power due to lower B+, but I will be happy with 10-12W or whatever it makes. It is interesting that George also commented on the low distortion of the JJ's. I could buy another Antek AN-0225 toroid with 2 x 24V windings at 230mA each that could be put in series with the power tranny giving approx 650 CT, for $11. Shipping will be free with the main tranny for an international order (up to 20lb is a flat rate). That would give a degree of flexibility.

Ian.

[millerlitescott]

Thanks Ian. I now have plenty of choices to start making my decisions.

I appreciate your help.

Scott

[tubelab.com]

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

I plan to offer the board AND the parts kit for $100 to $110. They can both be stuffed into a small flat rate box, so shipping is the same price as the board alone, until the USPS changes the rules again as they lost several BILLION dollars last year. The parts kit includes all of the small parts that go on the PC board, caps, resistors, tube sockets, screw terminals, and the diodes for 6CW5 builds. It does not include any tubes.

There is some work going on that may lead to a change in some resistor values. I have not verified the exact cost of some components in my latest spreadsheet since some of the vendors (Digikey) show no stock on some parts. After the values and costs are confirmed I will have an exact cost for the parts kits and offer them for sale.

Hammond 372HX, universal primary, 300-0-300@230mA, 6.3V@6A, 5V@3A, USD$120 Angela.com.
Hammond 372FX, universal primary, 300-0-300 @ 173mA, 6.3V@5A, 5V@3A, USD$105 AES, USD$83 Triode Elec.

I have both of these and they work.

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......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.

I have a 2T300, a 3T325 and a 2T350 on order. They will be tested upon arrival.

Possible output tranny choices........ George recommends 20-50W

I haven't tried any of these OPT's and I don't see it happening due to lack of funds. I bought a good supply of cheap OPT's that work well here, so that is what I use. My power recommendation is based on the fact that there is so much "interpetation" in OPT power specs. I will restate my recommendation in a more realistic manner. If you want an OPT that can deliver full power over the entire audio range (20Hz to 20 KHz) in this amp it should weigh at least 5 pounds. It takes that much iron to deliver 20 watts at 20 Hz. I have seen tiny OPT's that claim to handle 50 watts and big ones that are rated for 15, size matters.

[P.R. Audio]

Does anyone have a schematic for the simple p-p? I'm having a problem with the plates on the outputs, they have a slight glow and the 150ohm resistor in the power supply gets so hot that it melts the solder. Caps are all good and the right polarity.
Checked all the resistors and they are all in the right places.

[Ian444]

Some links to schems here - SP-P final connections?

Are you using 270 ohm cathode resistors on the output tubes and what is the B+?

Ian.

[P.R. Audio]

Everything is good, I had some Russian tubes that were a little under rated. Do not use 6n43n-E or 6p43p-E they are only rated for 185v.

[fenderkid]

i used a hammond ao29 amp that u can get for like 100$ at most or any hammond with that amp . built a 5e3 from it . used 90% of it and cost me 30$ . or if your bent on el84s i just picked up ( off the side of the road) a hammond L111 with a ao43 witch uses el84s in a pp that i will be converting . happy hunting