S-5 electronics amp kits

[cbutterworth]

In order to get a cheap amp built quickly for my office, I am thinking about the kits from S-5 Electronics.

There are two types of amp, one that uses 5670 and 6005 tubes, and another that uses 10GV8 tubes.

As far as I can tell, the 10GV8 tube amp is one that has been around for a while and folk reckon that it is pretty good for the money and ease of building.

Does anyone have experience with the other tubes (5670 and 6005) in the S-5 kit?

For a 8W into 8 ohm kit, the prices are around $170, the kit using the 5670/6005 being a touch more expensive.

I still haven't decided whether I'll buy one of these kits or go with El Cheapo or SimpleSE. However, I'll be using Lame encoded music from either my iPod or Mac, and I'll probably buy some of the small, cheap Sony bookshelf speakers.

Charlie

[Tom Bavis]

The 6005 is the military version of the 6AQ5, similar to the 6V6 in a miniature bottle although its ratings are a bit lower. Very good output tube, and available cheaply. The 5670 is a less common dual triode, but also not one in high demand, so they aren't expensive (except for the Western Electric version - 396A). The 5670 has another equivalent - 2C51 and recent Russian made ones are available too.

The 10GV8 (and its near equivalent 11MS8) were some of the last TV tubes designed, so they didn't have a long production life. So although they're cheap, who knows how long remaining stocks will last. My own tube stock contains 1-10GV8, 2-11MS8, 45-5670 and over 200-6AQ5. Now I DO own two amps that use 6AQ5 (and am likely to build another), but STILL - I have several lifetime's supply.

For a few dollars more, you get twice the power, and it uses tubes that will be available in the future. Down side is more heat with 10 tubes vs. 4... and it's 4 Ohm output - though an impedance mismatch won't matter at the lower power levels you're likely to use.

Either of these amps could benefit from better transformers, but that can wait until you have better speakers - most improvement will be at the low end.

[jduffy]

You might check out:

www.diytube.com

And do a search. There are a few lads there who have done some nice tweaks and can tell you what your options are.

There are also some online sites as well that have done some fun things with them.

Good luck.

[Jeb-D.]

I just saw their 16W version after you told me about it. Looks nice, but I think they are using the same output transformers as the 8W version. Just their using it with 4 ohm, so the primary impedance is halved, which doubles the current and power. Those OPT's get the job done for the 8W version, as it does fine in the low end. However, I think squeezing any more power out of them would result in pretty compramised sonic performance. Transformer upgrade would be a definite with the 16W version.

[gofar99]

Greetings, I have built and modded both the k-12 and a pp EL84. Both are good and IMHO the quality is largely based on three things. How clean your B+ and heater power is. The quaility of your coupling caps (I personally prefer Auricaps). How good the iron is ( I use EDCOR). The availability of tubes could be an issue in a number of years - so why not order a spare set or two. The k-12 tubes are available from several sources, I picked up a set of NOS RCA for $25US. The EL84 and variations being new can be had in matched sets at similar prices (Sovtek matched quartets can be had for under $30). I use CCS and a tube balancing circuit in my newer applications so exact matching is no issue. I think you will be happy with either amp.

[w5jag]

I have the 11BM8 push pull version sold by Antique Electronic Supply in my Ham Shack. It is a good value for the money, and I have not had much incentive to make any changes to it - it has a bit of hum, but with smallish bookshelf speakers it is not very significant.

If your budget is $200, and you are not married to push pull, you might consider this:

http://audio.engineeringvista.com/index.htm

It looks like a good kit. The SimpleSe is also a great amp and very flexible.

Win W5JAG

[cbutterworth]

Win,

thanks for the input. Right now I have settled for not building a new amp, but upgrading the PSU on my Aikido. This upgrade will free-up a 125-0-125 trafo and possibly a 6.3V filament trafo.

What I'll then do is to spend some time looking at various designs like El Cheapo and maybe Sy's amp.

As for an amp in my Ham-shack, well I don't have a shack, and I am sure that I would end-up broadcasting music by accident.

Charlie
KC0INE

[gmilitano]

It took me a while to clue in on the talk about the 5670 and 6005 tube. It appears that S-5 is launching a number of other kits, which include new 8 W and 16W kits, a tube preamp and a tone control. The new kits are based around the 5670 and 6005 tubes.

Link - http://s5electronics.com/thome.html

They say that "Due to popular demand and availability of certain components S-5 Electronics ..."

This ties in well with the discussion above about the future availability of the 10GV8 and 11MS8.

What I would be a little worried about and as mentioned by Jeb-D is that it appears that they are using the same iron as before. Aside from what Jeb-D mentioned about the OPT, I really hope they have beefed up the power transformer which runs on the hot side with 4 tube K-12.

For those interested in the original K-12, I put together a page which has a number of completed S-5 Electronics K-12 Tube Amp Kits and some links.

[gofar99]

Hi Everyone, My K-12 power transformer runs too hot to touch. I asked S5 about it and they said it was normal. One of my upcoming projects is a beefed up K-12. I have EDCOR outputs and power trannies for it. I plan on using a modified SMPS for the heaters as the power trannie has only 6 volt windings and I would like to use dc on the heaters. The SMPS is cheap ($17US) are are readily available. That solution appeals to the more frugal part of myself. The new S-5 kits ought to be fun to mod. If anyone does, how about posting your results?