first project.

[Weston]

Ive decided that for my first amp it might be best to go with a kit. My budjet is $200 tops. I was looking arround and it looks like a common kit was the k-12 and k-205 by s-5 electronics. It also looks like they have been discontinued, and replaced with ones kits of lesser sound quality. It looks like i could still get a 205 from antique electronics supply... but I was wondering if there are any other good kits within my budjet, or should i get a 205? or is there somwhere i can get a k-12? Any input is welcome.

[aardvarkash10]

what equipment do you have? What access to other stuff for making the chassis etc? WHat skills (if any) do you have already that may transfer to this project? Whats the outcome you are looking for? What does the kit have to work with ie what other stuff is in the chain - CD, speakers, etc. ? Sounds pedantic to ask, but it all informs the decision making process...

[Weston]

I know how to solder, and I understand basic circuitry...I was considering designing an amp arround some old tubes i found, but decided it wasnt worth the chance that they wouldnt work and the designing was a bit beyond my skills. Anyway, I work for a guy that makes household cabinets and can use his workshop and some cabinet grade wood to make a nice case. All in all, im looking to make a nice hi fi amp to take to school and use in my dorm.

[jrn77478]

I am far from an expert on tube amp construction, but I believe that you could do a lot worse than the Tubelab Simple SE.

http://www.tubelab.com/SimpleSE.htm

The single biggest expense will be the transformers, and Tubelab has proved that you can put good sounding iron in your kit for around $80. That leaves you $120 for the PC board and components. If you don't go crazy on the tubes or the lumber for your cabinet, you should be able to come in under budget.

[chrish]

I have built a circuit similar to those kit amps, and it works well, I have it in my office now. For a few dollars more, however, you could build a Tubelab Simple SE that would sound much better http://www.tubelab.com/SimpleSE.htm and still remain in your budget if you are careful.

Go with Edcor output transformers http://www.edcorusa.com/products/tra...se15-8-5k.html for $20 each or the slightly more expensive http://www.edcorusa.com/products/tra...se15-8-5k.html for $31 each. Allied power transformer 6K7VG http://www.alliedelec.com/Search/Sea...d=11B66B46E38B for $47 Triad 6H 200mA choke, also from Allied http://www.alliedelec.com/Search/Pro...ntent=967-1006 $16 .

Boards are $35 plus $8 shipping http://www.tubelab.com/PCB_order.htm

If you can build the box for nothing, that should be getting pretty close to your $200 limit. I have built the Simple SE and love it.

Chris

[chrish]

Ah, I see jrn77478 got in with similar advice while I was typing!

As for tubes, if you really want to save money, you can wait till later for the tube rectifier. I have used quite a few tubes in this setup. I think that the best sounding power tubes were the EL34s. I have tried JJ and winged C, both are good. JJE34L (high voltage version EL34) for about $30 a pair and JJ 12AT7 for about $10. I have a Mullard 12AT7 and I think that the JJ is almost as good, for a fraction of the price. I got mine from Antique Electrical Supplies because I had to ship to Australia, but I suspect that you could get these tubes from a music store that sells parts for guitar amps.

Chris

[Weston]

Yeah. That looks good. Really comprehensive instructions. lots of options. Easyish wiring. Low cost... I like it... With el 34's, 8 ohm speakers, and cheap edcor opt's how many watts is it good for? roughly.

[Zap]

Another Simple SE builder checking in

The amp will push a bit more in UL mode than in Triode, though Triode sounds better for some things. If I recall, EL34 will do ~5-6W in Triode. KT88 will do about 7-8W. (Per channel, of course). They are quite a bit louder than what most people think of for the wattage. The speakers will have an effect, too on the amount of sound produced.

The issue with the transformers will be bass response - I would highly recommend spending the extra money for the big CXSE Edcors, IF you can (especially depending on what you are listening to). They come at a cost of about $60 each, though. The upside, is that you can always replace them later if you feel you need better bass response.

[Weston]

Are the small ones that bad? I am a bass player, and do prefer to hear the bass... but I cant afford 60 opts right now. I found an older teac tape deck today with a nice pair of VU meters. Can UV meters be incorporated in the circuit.... or is it really hard to make them work?

[chrish]

Originally posted by Weston
Are the small ones that bad? I am a bass player, and do prefer to hear the bass... but I cant afford 60 opts right now. I found an older teac tape deck today with a nice pair of VU meters. Can UV meters be incorporated in the circuit.... or is it really hard to make them work?

NO, the small ones are very good. According to Tubelab, who tested these transformers, they are great in the middle and upper frequencies, better than the larger Edcors. The larger ones did go lower though. I am usig the $20 Edcors in my main system, but have woofer units crossed over at 80Hz. Everyone wants 'good bass', but what are your speakers capable of? The $20 XSE Edcors are 15 watts rated 70Hz-18KHz. The GSXE $30 Edcors are 15 watts rated 40Hz-18KHz. The CXSE $83 Edcors are rated 25 watts 20Hz-20KHz. With tubes you need lots of extra iron in the transformers to reproduce low frequencies. If you are on a tight budget you will have to make compromises. If you do want more bass extension I would recommend the GXSE $30 transformer. I have some of these, but have not incorporated them in to a design yet. They are quite a bit beefier than the $20 units.

Chris