Tube Amp DIY or Retail

[Bengali]

Hi,

looking for a tube amplifier in price range of $100-300, either DIY or retail.
Is that price range doable or wishful thinking?

Any of those chinese ebay units any good?

I've listened to the primaluna pro 5 before, KT88's, it sounded very nice.

What does the 300B sound like? warmer than the KT88? wider sound stage?

The bottlehead 300B is nice but too much for me. 7-10W range should suffice.

thanks

 

[Loren42]

Well, a good set of tubes for a PP KT88 amp will push you toward $300, let alone the cost of the transformers, chassis, and components. You could do a lot better with $600 to $800 as a starting point.

You can buy the Chinese amps, but you will need to modify/fix the amp at some point. Still, that is an option some people go.

I am more of the mind to just pay the price up front and do it right the first time because if you buy something that is cheap, then you replace or modify it to get it where you want it, you end up paying twice.

The other thing is that do get an education with the Chinese amps, it just costs you $300.

If you check around you should be able to find some lower priced kits or DIY boards from TubeLab. TubeLab's boards would be a much better investment.

 

[mikejennens]

Some have built this one and seem quite happy with it. https://id3466.securedata.net/s5electronics/forms/gtubeorder.html Plus, there are a handful of websites with upgrades for it too.
I found an old console in a thrift store and pulled the amp. I cleaned it up and recapped it for a total cost of about $120. There are other vintage tube amps that are very well regarded that you should be able to get in your price range.
Mike

 

[nightanole]

Id snipe a fisher console on ebay. Then gut it and rebuild with a modern layout. Then you would have good iron, and the chassis ready to go, you just need to solder.

 

[tim614]

What does the 300B sound like? warmer than the KT88? wider sound stage?

i have listen to a few 300b (not all), a "TRI 300b" and "DRD 300b" they are ok, the TRI were better.
but when i compare to SE kt88, i like the se kt88 better, to me 300b are not bad tubes, just over rated in my opinion.
$100-$300 i would buy, cause good diy can cost alverage $300 and up.
tranys alone will exceed the $300 price range.

 

[Eli Duttman]

looking for a tube amplifier in price range of $100-300, either DIY or retail. Is that price range doable or wishful thinking?

It's tight, but looks doable. Edcor makes just under $50 O/P trafos (CXPP25-n-7.6K ) that will work in a UL mode "El Cheapo". That gets you about 12 WPC. Jim McShane sells parts kits and tubes for the project. If the fact that 'AQ5s are out of production bothers you, build with 6V6s. No parts value changes are necessary.

BTW, what sort of speakers are you planning on mating to the amp? What is the nominal impedance of the speakers? Do you know what the speakers' impedance curve looks like?

 

[roline]

You could do a Compactron PP Amp.... ~$100 for the iron and the tubes are still cheap.

 

[roline]

If you want to, upgrade the output iron and up the tubes to the 35 watt flavor.... Triode outputs sound sooo good.

 

[pjanda1]

You need to figure out what your priorities are and what you are willing to live with. $100-300, to me, means that you'll need to scour for an old donor amp. Sure, you can get under $300 with major parts for an inexpensive amp, but by the time you add all the little bits, I don't see it happening. And no matter what, things like 300Bs or higher power push pull (KT88s) are out of the question. Donor chassis can yield interesting things though. My current amp is based on the monoblocks from an Akai M8 reel to reel. My last amp used the output transformers from a Sherwood integrated. I picked each of those up for $25. The Akai based amp probably ended up under $300. The other, based on Eli's El Cheapo, despite using many recycled parts, probably ended up around twice that. And these use cheap tubes!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

 

[dnewma04]

There is a thread in the tube section at audiokarma.org that you can build for 150-250.00 using 6LR8 or 6LU8 tubes. It's a little SE job good for 5-6w.

 

[Bengali]

thanks for all your input.

it would be to drive a pair of monitors(Polk Rti 3A). I don't need high output power. just easy listening.

I had a primaluna pro 3 and pro 5 some time ago. I really loved the sound those put out. probably too many variables in diy to find something similiar in sound.

I'm going to try the ZCA 2sk1058 first, if that works well enough, I will leave the diy tube amp stuff alone. I've done the aikido's but never an actual tube amp.

so it seems the O/P transformers are similiar to caps, they will affect the sound depending on quality/price(?)

 

[mackinthebox]

I have an old console tube amp from a magnavox console
I replaced a few caps and resistors and added a power cord and it sounds amazing, ive spent no more than 150 on the amp and parts so far...

there are lots of console amps on ebay and some that have even been recapped and are ready to run

 

[roline]

Inexpensive PP amp

Edcor has Pete Millets Engineers amp transformer set for $165, 25 watt output iron. 6P3s output tubes are $3 each, input tube around $1. You can build an amp 25watts/channel for under $300....
If you want EL34's fleebay has some for under $24/quad..ya from China.
The 25 watt 8k-8 outputs that were in the first Compactron were $65 delivered, I used the $20 10lb'r for power. I'm still playing with this design to see how stable it is, triode mode next. It is wonderful at 365Volts with SV6550-C- output tubes, 6k output transformers in UL mode. It was sweet with the 6P3S's also...