I'd just buy a Dynaco or similar, but they're out of the budget for this application. I have a few transformers and a pile of vac tubes plus some other parts, but it seems to me by the time I buy a chassis and the missing filler parts, I'll easily be at what a decent Chinese amp kit costs. There's a Class AB push pull amp there on Ebay for $219 complete with everything, ready to solder together. Just seems like it's the way to go in the interests of time sourcing/scrounging all the parts. Any thoughts on this as a good home music amp?
https://www.ebay.com/itm/133481896420
https://www.ebay.com/itm/133481896420
Last edited by a moderator:
The problem with those kits is that they come with the cheapest parts on the planet, and usually no instructions. Also, uncommon tubes not normally found in the US could be an issue.
jeff
jeff
6P1 is a common Chinese / Russian tube, they don't cost much due to little demand. Characteristics similar to 6V6, but unique pinout; no US / Euro equivalent. 6F2 is equivalent to 6U8; many pin-compatible tubes such as 6GH8, 6BL8, etc. May require a resistor change...
Instructions are typically sketchy, sometimes no more than a schematic. Performance should be similar to a Magnavox or other console amp, appearance is obviously better.
eBay hint: when you post a link, delete everything after the "?". (Amazon too...)
Instructions are typically sketchy, sometimes no more than a schematic. Performance should be similar to a Magnavox or other console amp, appearance is obviously better.
eBay hint: when you post a link, delete everything after the "?". (Amazon too...)
Last edited:
An EL84 amplifier can be cheap, particularily an SE, and they are really hard to screw up. Our build cost <$100. The push-pull was pricier, but ranks right up with my SIT-3.
We did have a bunch of transformers from consoles that owed us nothing.
dave
We did have a bunch of transformers from consoles that owed us nothing.
dave
Think about a BoyuuRange REISONG a10 or A12 amplifier. Stephie of Skunkie Designs has posted complete build instructions in a series of videos on YouTube.
https://www.ebay.co.uk/itm/116228789307?
https://www.ebay.co.uk/itm/116228789307?
Another kit on ebay: https://www.ebay.com/itm/224146944838
Xraytonyb on youtube has a build series:
Someone on this forum has built a couple of them as well.
Steve
Xraytonyb on youtube has a build series:
Someone on this forum has built a couple of them as well.
Steve
I'd go for a Spud design. You can find inspiration here: https://neurochrome.com/pages/novar-spud
Tubelab's SSE would be another good option. George (Tubelab) provides tons of support for his products. http://tubelab.com/designs/tubelab-sse/
Tom
Tubelab's SSE would be another good option. George (Tubelab) provides tons of support for his products. http://tubelab.com/designs/tubelab-sse/
Tom
I heartily second Tom's suggestions. I built both the Novar Spud and Tubelab's SSE. They are both excellent amps -- straight forward to build and relatively inexpensive.
William
William
If you can't afford what you want, save your money until you do. I'd steer clear of those Chinese kits. The transformers is the most critical component, both in performance and cost. That said, they don't necessarily need to be exotic. I recently built an awesome amp using 6360 in PP using Antek 25VA power toroidals as output iron. Best sounding amp I've ever built.
Tubelab SPP fun to build and sounds great, it's playing right now in my system.
I will say, there is no such thing as an 'inexpensive tube amp'.
There is 'simple' tube amp, a 'complicated' tube amp. Both of them could be built with cheap parts and sound ok or with different or super expensive parts and sound different. Some parts have really disproportionate effect on the sound so attention is needed.
I will say, there is no such thing as an 'inexpensive tube amp'.
There is 'simple' tube amp, a 'complicated' tube amp. Both of them could be built with cheap parts and sound ok or with different or super expensive parts and sound different. Some parts have really disproportionate effect on the sound so attention is needed.
Often, the Chinese products do not list the power mains voltage. 100, 110, 115, 120, 220, 240VAC
Be careful.
The link in Post # 1, for example . . . one picture shows the power transformer, with 115V marked on the paper bottom.
So many Chinese kits use PCBs. Too difficult to modify, "subsgtitute" tubes with different pin-outs and PCBs will not work.
Some Chinese kits are better than kits that have the problems that are listed above.
On kit I got had a steel chassis that was mildly magnetic . . . watch out for hum problems.
And, the chassis could cut your hand, there were sharp edges.
Be careful.
The link in Post # 1, for example . . . one picture shows the power transformer, with 115V marked on the paper bottom.
So many Chinese kits use PCBs. Too difficult to modify, "subsgtitute" tubes with different pin-outs and PCBs will not work.
Some Chinese kits are better than kits that have the problems that are listed above.
On kit I got had a steel chassis that was mildly magnetic . . . watch out for hum problems.
And, the chassis could cut your hand, there were sharp edges.
zintolo,
Aluminum is fairly easy to drill, use a chassis punch, use a nibbler, etc.
It does not magnetically transmit hum from the power transformer and the B+ choke . . . to the output transformers.
It is less strong than steel.
With an aluminum chassis, hum is controlled by using large space from the output transformer to both the power transformer and to the B+ filter choke.
And hum is also controlled by keeping the coils of the output transformers at right angles versus the power transformer and the B+ filter choke.
Steel chassis are strong.
But most are magnetic, and will magnetically transmit hum from the power transformer and the choke to the output transformers.
The magnetic hum is transmitted all across the chassis.
A typical choke has all the E laminations through one side of the coil, then an air gap, and all the I laminations on the other side.
I use choke input filters for B+, so there is lots of magnetic spray from the choke.
A power transformer uses Interleaved laminations, E then I, E then I, etc. The E comes through one side of the coil, and an I on the other side of the coil covers the 3 ends of the E. The next E goes through the other side of the coil, and the next I is on the same side of the coil as the first E.
This alternating pattern is repeated for all the laminations.
There is NO air gap.
The power transformer often transmits less magnetic field than a choke that is used on a choke input filter.
Single ended output transformers often have all the Es through one side of the coil, and all the Is cover the 3 ends of the Es. There is an air gap between the Es and Is.
That makes the transformer very sensitive to magnetic hum fields from the power transformer and the choke.
Push pull transformers often Interleave the E and I laminations, just like the power transformer. There is no air gap.
The push pull transformer is less sensitive to magnetic hum fields versus the single ended transformer.
zintolo, you know most of this already, but newbies might benefit from the info.
Aluminum is fairly easy to drill, use a chassis punch, use a nibbler, etc.
It does not magnetically transmit hum from the power transformer and the B+ choke . . . to the output transformers.
It is less strong than steel.
With an aluminum chassis, hum is controlled by using large space from the output transformer to both the power transformer and to the B+ filter choke.
And hum is also controlled by keeping the coils of the output transformers at right angles versus the power transformer and the B+ filter choke.
Steel chassis are strong.
But most are magnetic, and will magnetically transmit hum from the power transformer and the choke to the output transformers.
The magnetic hum is transmitted all across the chassis.
A typical choke has all the E laminations through one side of the coil, then an air gap, and all the I laminations on the other side.
I use choke input filters for B+, so there is lots of magnetic spray from the choke.
A power transformer uses Interleaved laminations, E then I, E then I, etc. The E comes through one side of the coil, and an I on the other side of the coil covers the 3 ends of the E. The next E goes through the other side of the coil, and the next I is on the same side of the coil as the first E.
This alternating pattern is repeated for all the laminations.
There is NO air gap.
The power transformer often transmits less magnetic field than a choke that is used on a choke input filter.
Single ended output transformers often have all the Es through one side of the coil, and all the Is cover the 3 ends of the Es. There is an air gap between the Es and Is.
That makes the transformer very sensitive to magnetic hum fields from the power transformer and the choke.
Push pull transformers often Interleave the E and I laminations, just like the power transformer. There is no air gap.
The push pull transformer is less sensitive to magnetic hum fields versus the single ended transformer.
zintolo, you know most of this already, but newbies might benefit from the info.
Thanks @6A3sUMMER ,
I indeed already used Aluminium (softer, easier to be drilled) or AISI316L (laser cut, already bent, and hope there are no errors), but was curious to know if there’s anything more that I could use.
I’m sure newbies will benefit alot, but I will learn for sure alot from your knowledge!
I indeed already used Aluminium (softer, easier to be drilled) or AISI316L (laser cut, already bent, and hope there are no errors), but was curious to know if there’s anything more that I could use.
I’m sure newbies will benefit alot, but I will learn for sure alot from your knowledge!
Without kidding, you are lucky to be able to find a magnavox stereo console amp for peanuts, it is a fantastic playground and a completely honorable chassis which accepts transplants without flinching, I will be you, I will go towards that directly.
here in Europe, we don't have access to good bases like this.
here in Europe, we don't have access to good bases like this.