Sorry for what is probably a newbie question but please bear with me! I have always liked the sound of valve equipment and have been thinking for some time about building a valve amp. I have sufficient electronics skills and have repaired a few valve radios, but I do not have the equipment or skills to fabricate a chassis or PCBs, so I'm thinking that a kit might be the way to go. I would like the amp to be stereo and have a pre-amp stage if possible. I have noticed that some designs use at least some semiconductors which I do not object to although I am aware that the purist would consider only valves.
I have searched for a while and there seem to be a lot of different kits around. Some come from the far east via eBay and Amazon and appear to be reasonably priced but I have concerns over quality of components and therefore ultimately how they might perform, although I understand some aspects can be improved by upgrading the originally supplied components. It goes without saying that I don't want to spend my hard earned cash on a piece of junk. On the other hand, you get what you pay for, and I have seen other kits from perhaps more specialist vendors that are very expensive (i.e. in excess of 1k or as much as even 3k!) and am wondering whether it is better to save up for another year or two.
Before I decide what to buy I also have a couple of questions:
1. What is the advantage of single ended amps over push pull?
2. Since extra grids on the pentode were added so as to solve certain problems with the triode, why do some consider a triode output stage superior?
3. I understand that due to the nature of valves, valve amps have a problem with response below 100hz. Do modern valve amp designs solve this, or is this a limitation one must live with?
My total budget is around £500 (or around 700USD), although by the time import costs are considered it might as well be 500USD. Is this sufficent to build something that might be upgraded later?
I have searched for a while and there seem to be a lot of different kits around. Some come from the far east via eBay and Amazon and appear to be reasonably priced but I have concerns over quality of components and therefore ultimately how they might perform, although I understand some aspects can be improved by upgrading the originally supplied components. It goes without saying that I don't want to spend my hard earned cash on a piece of junk. On the other hand, you get what you pay for, and I have seen other kits from perhaps more specialist vendors that are very expensive (i.e. in excess of 1k or as much as even 3k!) and am wondering whether it is better to save up for another year or two.
Before I decide what to buy I also have a couple of questions:
1. What is the advantage of single ended amps over push pull?
2. Since extra grids on the pentode were added so as to solve certain problems with the triode, why do some consider a triode output stage superior?
3. I understand that due to the nature of valves, valve amps have a problem with response below 100hz. Do modern valve amp designs solve this, or is this a limitation one must live with?
My total budget is around £500 (or around 700USD), although by the time import costs are considered it might as well be 500USD. Is this sufficent to build something that might be upgraded later?
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You are going to have budget problems. Magnetics are expensive, especially SE O/P "iron". Without arguing pros and cons, this fact alone indicates build PP circuitry.
Well designed tube circuitry will be "flat" throughout the entire 20 - 20000 Hz. band. FWIW, the Harman/Kardon Citation II easily bests very many SS amps in the bass performance area.
A deep, heavy wall, commercial kitchen, aluminum baking pan makes a good low cost chassis. IMO, this is your best bet, when financial constraints are present.
What sort of speakers do you plan on using. The amount of power O/P yielded is directly tied to speaker behavior. Amps and speakers form an "organic" whole.
Well designed tube circuitry will be "flat" throughout the entire 20 - 20000 Hz. band. FWIW, the Harman/Kardon Citation II easily bests very many SS amps in the bass performance area.
A deep, heavy wall, commercial kitchen, aluminum baking pan makes a good low cost chassis. IMO, this is your best bet, when financial constraints are present.
What sort of speakers do you plan on using. The amount of power O/P yielded is directly tied to speaker behavior. Amps and speakers form an "organic" whole.
I Buy and Build this kit : https://momchil.wordpress.com/2013/11/01/diy-кит-усилвател-6э5п-гу50/
Great for the price and the GU50 tube is a beast...
Great for the price and the GU50 tube is a beast...
i have to update the pictures, the amp is almoust ready.
A Spud (single-tube) amplifier is a good way to get started with valve/tube amplifiers. My Novar Spud can be built for around $200 (board, components, iron) using the small Edcor XSE output transformers. If you want better performance, the Edcor CXSE transformers are incredible value for the money. With the CXSE transformers, the budget gets up to about $300. Then add chassis.
Tom
Tom
I do not claim to be an expert, however:
1- Single ended triode blah blah - is a purist route, sometimes a black art, the quality of (spelt expensive) components are a key feature.
with your budget stay away.
Some argue that single ended designs sound the best, Naah!
it is a belief that started in Japan, even Tim de Paravicini of EAR, Lux, MFSL (& many more) believes single-ended is over-rated at best.
2- No problems with bass output, don't worry! Bass players love valve amps (so I've been told)
3- with your budget, try to pickup an Edison 12 or similar from eBay (google it) and modify it.
it is a simple EL84 push-pull poweramp of some 12 watts.
If you modify it to manual bias, upgrade the powersupply (better caps and a choke) you get over 15 Watts clean from it.
It has decent transformers, and with a little modification (bypass the first tube) you could feed it a DAC signal direct (& use a digital volume).
I have one at my office and it sounds great through my Sonus Faber Concerto's.
As mentioned earlier in some reply, you need the right speakers too.
Good luck.
1- Single ended triode blah blah - is a purist route, sometimes a black art, the quality of (spelt expensive) components are a key feature.
with your budget stay away.
Some argue that single ended designs sound the best, Naah!
it is a belief that started in Japan, even Tim de Paravicini of EAR, Lux, MFSL (& many more) believes single-ended is over-rated at best.
2- No problems with bass output, don't worry! Bass players love valve amps (so I've been told)
3- with your budget, try to pickup an Edison 12 or similar from eBay (google it) and modify it.
it is a simple EL84 push-pull poweramp of some 12 watts.
If you modify it to manual bias, upgrade the powersupply (better caps and a choke) you get over 15 Watts clean from it.
It has decent transformers, and with a little modification (bypass the first tube) you could feed it a DAC signal direct (& use a digital volume).
I have one at my office and it sounds great through my Sonus Faber Concerto's.
As mentioned earlier in some reply, you need the right speakers too.
Good luck.
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When you will Play with a single Endet Amp you need good Speakers with a high Intensyty bigger than 90dB/W and relativly linear resistence over the Frequency. With your budget by an used Push-Pull Power-Amp like the Dynavox VR-70 or similar and modify it. It is a good base to hear music and learning something about Tube-Amps. I spend <500$ for the complete Amp incl. Some modifikationes. Today I'm on the way to make my own Amp-Design without compromise and this means also to spend more than 2k$ for the technic. Really good Amplifiers cost a lot. So my Opinion: Start like me with an ready China-Amp and learn to modify it.
A few interesting suggestions being proposed even all the way from Chile!. I've sent the vendor an e-mail asking for the price of the GU50. I am intrigued also by both the spud and the Edison 12 and I noticed while Googling this that there is also an Edison 60 as well and it might be possible to source one within the UK, which I am seeking to confirm and get some idea of price. I haven't had a chance to do an eBay search yet though.
My speakers are Boston A26s and have a sensitivity of 89db, so just a shade short of the 90db that is recommended. Would they still be suitable?
Regarding the Dynavox, I can see they are listed on Amazon.de so are also an interesting option. Again, there are other options such as the Dynavox 20 which is slightly more expensive but the listing does not appear to state which valves it is using. I must also admit that I don't like the appearance of the capacitors protruding halfway through the chassis on these two amps. Another amplifier that came up as an option was the GemTune which also has 4.5 stars and I think is nicer in appearance, but is it as good as the Dynavox?
My speakers are Boston A26s and have a sensitivity of 89db, so just a shade short of the 90db that is recommended. Would they still be suitable?
Regarding the Dynavox, I can see they are listed on Amazon.de so are also an interesting option. Again, there are other options such as the Dynavox 20 which is slightly more expensive but the listing does not appear to state which valves it is using. I must also admit that I don't like the appearance of the capacitors protruding halfway through the chassis on these two amps. Another amplifier that came up as an option was the GemTune which also has 4.5 stars and I think is nicer in appearance, but is it as good as the Dynavox?
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If you really don't want to make a chassis, you could do a lot worse than something like this: DIYTube Dynaco ST35 Tube DIY Amp Kit - NEW REV. E! Great for iPod
It is a well tested push/pull design that will have plenty of power to drive your speakers to respectable volume.
If you could find someone to help with the metalwork, other options open up like the SPP from tubelab.com or something similar.
You certainly don't need to spend $1k+ to get something that'll sound great.
Good luck.
It is a well tested push/pull design that will have plenty of power to drive your speakers to respectable volume.
If you could find someone to help with the metalwork, other options open up like the SPP from tubelab.com or something similar.
You certainly don't need to spend $1k+ to get something that'll sound great.
Good luck.
You are in pushpull EL34/KT88 territory , you probably need in excess of 20wpc for your amp . You should really start off with more suitable speakers if you want flexibility with regards to your amp design , there are some Beyma co-axials which are reasonably inexpensive and offer good sensivity . I would suggest avoiding these 'cheap' overseas kits , which will end up more costly when it comes down to import duties/shipping and getting the things working correctly . You need to consider that alot of these kits have 220V or 230V mains transformers which will over run on UK 240V mains . I took a look at the GU50 kit and the output iron specs looked very lossy and small with low primary inductance , chokes also had excessive DCR for their rating . Probably a good amp but you get what you pay for , there are no bargains in audio when it comes down to iron , especially output transformers
316a
Speakers are small and sensitive, 10 or 12 W is all you need.
Remember "tube watts are bigger!"
Although not technically true, but 12W from a tube amp is plenty for such speakers.
Edison 12 ( or Aria 12, world audio design 12 ) or audio innovations 200 are all similar.
You can pick one up from eBay for about £200 - modifications will not cost more than £100 - you don't need to worry about metalwork either.
For £300 (less than $500) you get a very good 15W amp.
I challenge if anyone can come up with a kit at that price that would come close, never mind beat!
Thanks Ken. I will search on the other names (Aria, world audio design, audio innovations) as well. I would tend to agree that 10 to 12 watts is probably than adequate. Although 15w to 20w would be desirable, as has been said, the cost of iron rises substantially adding to the overall construction cost.
There seem to be a few options on Amazon UK as well, including several amps from YAQUIN. Anyone have any experience of these?
I am beginning to like the idea of a buying a pre-owned amp to refurb or mod from eBay instead of a kit though.
It is my understanding that the UK now has 230v mains in line with the standard for the rest of Europe, rather than 240v. I also understand that mains voltage can vary somewhat during the day or night. In any case, I can easily check what I'm getting delivered to my location on average by taking a reading or two with the AVO at various times of the day. Obviously cheaper transformers may be less tolerant to being slightly overrun than good quality iron and may run a bit on the hot side, but most modern equipment you buy here is rated for 230v nowdays and usually runs OK in the UK so I'm not sure it will be much of a problem. Nevertheless, the point is noted.
PS, re: Tubelab. I actually cvame across the site prior to posting, but thanks for mentioning it. It does have some very useful information and the author appears to sell various PCBs to build amps on. It would seem that their designs are hybrid, being supplemented by a MOSFET stage and it is claimed that the resulting amp sounds better. I don't mind using semiconductors provided there is a benefit in terms of audio quality. On the other hand, the silicon could be omitted from the design and left of off the board. I'm not sure at this point whether to take the purist route and stick to tubes only or whether to experiment. As they say, the jury is out on that one.
There seem to be a few options on Amazon UK as well, including several amps from YAQUIN. Anyone have any experience of these?
I am beginning to like the idea of a buying a pre-owned amp to refurb or mod from eBay instead of a kit though.
It is my understanding that the UK now has 230v mains in line with the standard for the rest of Europe, rather than 240v. I also understand that mains voltage can vary somewhat during the day or night. In any case, I can easily check what I'm getting delivered to my location on average by taking a reading or two with the AVO at various times of the day. Obviously cheaper transformers may be less tolerant to being slightly overrun than good quality iron and may run a bit on the hot side, but most modern equipment you buy here is rated for 230v nowdays and usually runs OK in the UK so I'm not sure it will be much of a problem. Nevertheless, the point is noted.
PS, re: Tubelab. I actually cvame across the site prior to posting, but thanks for mentioning it. It does have some very useful information and the author appears to sell various PCBs to build amps on. It would seem that their designs are hybrid, being supplemented by a MOSFET stage and it is claimed that the resulting amp sounds better. I don't mind using semiconductors provided there is a benefit in terms of audio quality. On the other hand, the silicon could be omitted from the design and left of off the board. I'm not sure at this point whether to take the purist route and stick to tubes only or whether to experiment. As they say, the jury is out on that one.
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you're welcome.
Don't worry about voltage fluctuations , or the exact voltage. UK and EU are pretty good at maintaining the voltage.
The mentioned amps, can give cleaner output up to 17W (15W for sure) if you modify them into manual bias, upgrade your caps, and add a decent choke.
Also change all your signal caps for paper-in-oil cheepos from soviet K409-4Y.
Good luck.
These amps have very good transformers ( Iron?) for the money - they are clean to rated power, and beyond, specially with manual bias.
BTW these old British gems, beat the pants off any Chinese at similar cost.
Don't worry about voltage fluctuations , or the exact voltage. UK and EU are pretty good at maintaining the voltage.
The mentioned amps, can give cleaner output up to 17W (15W for sure) if you modify them into manual bias, upgrade your caps, and add a decent choke.
Also change all your signal caps for paper-in-oil cheepos from soviet K409-4Y.
Good luck.
These amps have very good transformers ( Iron?) for the money - they are clean to rated power, and beyond, specially with manual bias.
BTW these old British gems, beat the pants off any Chinese at similar cost.
here is one
HFA12 Valve Power Amplifier. Made in Britain. Recently Serviced. 12 wpc. | eBay
this a HiFi Answers replica.
HFA12 Valve Power Amplifier. Made in Britain. Recently Serviced. 12 wpc. | eBay
this a HiFi Answers replica.
The HFA12 looks good and is a serious contender! However, I have also come across something interesting. Its a part kit, World Audio Design KAT34, apparently designed by Andy Grove (although I am not familiar with the name) including chassis, transformers, choke, a couple of valves and some other bits including the valve bases.
The transformer and choke details have been specified as:
Of course, the HFA12 has the advantage of being complete and ready to go and maybe can be upgraded as well and is at a price well within my budget which makes it very tempting...
The transformer and choke details have been specified as:
I'm not sure what the 14 percent refers to? Apparently its supplied with circuits diagrams, build instructions but will still require some additional parts and valves. Provided the above transformers are OK, I am wondering whether it might be a good starting point? If I can get it at a reasonable price (maybe less than £100) then it would give me a starting point and something to build on then maybe I could build it up gradually and spread the cost over a period of time.
Of course, the HFA12 has the advantage of being complete and ready to go and maybe can be upgraded as well and is at a price well within my budget which makes it very tempting...
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Tubelab have a few different designs: a couple of single ended triode versions, and a push pull. I made the latter using the PCB and parts kit (i.e. caps, resistors, tube sockets, connectors) available from tubelab. It doesn't use any silicon - I made the version with valve rectification, 12AT7s and EL84s. I source my transformers from Edcor, but shipping was expensive to Australia. I've been very pleased with mine.
Forget single ended rubbish.
It always was for nasty cheap budget 1960s radios and nothing changed.
Old monobloc amplifiers are cheap, because today everyone wants a pair.
Eg:-
Someone sold an old Bogen Db110 on Ebay yesterday for £45....you read right 45 quid (69USD)!
That's an amplifier that's 60 years old, but will probably run happily for another 30.
They look scruffy which is why nobody wants them, and the circuitry is relatively simple and straight forward.
Another J50 monobloc using 807s last week also went for a song.
I think there's still a DB20, with 6L6 for sale just now which refuses to sell in weeks.
No-one wants it for £180!
That's a 35W pretty serious piece of amplifier for not a lot of dough, and the learning curve consists of taking it to bits, renewing some parts, and throwing away the sections you don't want/don't need.
Even changing the power transformers, buying brand new 230V bespoke ones to replace 110V ones, from Sowter UK would give you pretty much the best 20W valve amplifier in the world costing peanuts, and you can rechassis it, and upgrade the components at the same time, cheap too.
6V6 might be old, but they can take an enormous thrashing & there's nothing to touch them on the market today, (+ Bogen wound their own top quality transformers!)
It always was for nasty cheap budget 1960s radios and nothing changed.
Old monobloc amplifiers are cheap, because today everyone wants a pair.
Eg:-
Someone sold an old Bogen Db110 on Ebay yesterday for £45....you read right 45 quid (69USD)!
That's an amplifier that's 60 years old, but will probably run happily for another 30.
They look scruffy which is why nobody wants them, and the circuitry is relatively simple and straight forward.
Another J50 monobloc using 807s last week also went for a song.
I think there's still a DB20, with 6L6 for sale just now which refuses to sell in weeks.
No-one wants it for £180!
That's a 35W pretty serious piece of amplifier for not a lot of dough, and the learning curve consists of taking it to bits, renewing some parts, and throwing away the sections you don't want/don't need.
Even changing the power transformers, buying brand new 230V bespoke ones to replace 110V ones, from Sowter UK would give you pretty much the best 20W valve amplifier in the world costing peanuts, and you can rechassis it, and upgrade the components at the same time, cheap too.
6V6 might be old, but they can take an enormous thrashing & there's nothing to touch them on the market today, (+ Bogen wound their own top quality transformers!)
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