Hi, I am a senior in highschool, so I don't run across alot of money, however my pride and joy are my JBL e60s which ran me a good 400 bucks, my HK3480 reciver ran me another 350, however now I want to explore the world of DIY tube amps, preferably Single-Ended. My E60s are rated with an efficientcy rating of 90db at 1watt/1meter, so my question to all of you intelegent, gifted, rolemodels, do you think i can get enough kick out of a 1 or 2 watt tube amp?
I guess the answer is "it depends". However I think you will be OK with those speakers if you don't expect ear-splitting volume or listen in a huge room. I listen to a pair of SE monoblocks with 89dB speakers and think they sound great. However my amps do make a good 6-7 watts.
I also listened to an SE EL84 amp (2W) with those same speakers. The sound was very good at "normal" listening levels but that amp just couldn't do "loud" with those speakers.
Do a search for Mikael's SE KT88 amp schematic in this forum. An easy to build SE UL amp, good sound, KT88s look cool and it can easily make 6 watts.
The problem with SE amps is you need hefty output iron which can be both expensive and heavy. For Mikael's schematic a Hammond 1628SE would work and be relatively inexpensive. For about the same price (from Euphonia Audio) I can personally recommend the James 6123HS. For a bunch less cash ($18) people have been reporting good results with the Edcor SE trafo.
HTH,
I also listened to an SE EL84 amp (2W) with those same speakers. The sound was very good at "normal" listening levels but that amp just couldn't do "loud" with those speakers.
Do a search for Mikael's SE KT88 amp schematic in this forum. An easy to build SE UL amp, good sound, KT88s look cool and it can easily make 6 watts.
The problem with SE amps is you need hefty output iron which can be both expensive and heavy. For Mikael's schematic a Hammond 1628SE would work and be relatively inexpensive. For about the same price (from Euphonia Audio) I can personally recommend the James 6123HS. For a bunch less cash ($18) people have been reporting good results with the Edcor SE trafo.
HTH,
I have Yamaha NS-10 studio monitors. They are rated for 87db. I have several tube amplifiers, both SE and P-P, from 2 to 40 watts. In a small listening room (10 X 11 feet) the 2 watt SE 45 amp sounds great, but won't do loud very well, and can't play some music (Jimi comes to mind) at any volume. On the other hand the 30 and 40 watt amps will chase you out of the room.
I have recently been experimenting with a SE ultralinear (UL) amp using a $3 TV tube (6AV5) and the previously mentioned $18 Edcor transformers (XSE-15-8-5K).
I applied cathode feedback to the design, and it ROCKS. Even with my 87db speakers I can play Jimi loud! The amp makes about 7 to 9 watts depending on how hard you push the tube. The cathode feedback really tightens up the bass, and allows you to run the amp volume up into the distortion zone without destroying the sound (within reason). This makes for a loud (but good) sounding amp, which can be built for minimum dollars.
I won't have the schematic on my web site until the middle of April due to an impending road trip. In the mean time look at the link below. It has the schematic for a similar design and the theory as to why this design works well.
http://www.lundahl.se/pdfs/claus_byrith/cb-amplifier_8wse.pdf
I have recently been experimenting with a SE ultralinear (UL) amp using a $3 TV tube (6AV5) and the previously mentioned $18 Edcor transformers (XSE-15-8-5K).
I applied cathode feedback to the design, and it ROCKS. Even with my 87db speakers I can play Jimi loud! The amp makes about 7 to 9 watts depending on how hard you push the tube. The cathode feedback really tightens up the bass, and allows you to run the amp volume up into the distortion zone without destroying the sound (within reason). This makes for a loud (but good) sounding amp, which can be built for minimum dollars.
I won't have the schematic on my web site until the middle of April due to an impending road trip. In the mean time look at the link below. It has the schematic for a similar design and the theory as to why this design works well.
http://www.lundahl.se/pdfs/claus_byrith/cb-amplifier_8wse.pdf
Personally, I very much doubt if anything less than 10w would be adequate but it depends on your need to allow sufficient headroom to avoid distortion of transients. The type of music you like will dictate this: e.g. symphony orchestras and choirs need plenty of headroom, while pop, rock and most types of jazz are relatively free from large transients.
AM,
A useful rule of thumb is that the amp/speaker combo should be capable of 102 dB. peaks. So, 1 W. = 90 dB., 2 W. = 93 dB., ..., and 16 W. = 103 dB. A 15 WPC amp seems indicated. Also, how is the SPL rating of your speakers specified? If they are 4 Ohm nominal and the rating is specified for a 2.83 V. drive, the true efficiency is 87 dB.
You could get the power you need from push/pull EL84s. SE amps above 8 WPC cost big bucks.
An option you might consider is the construction of a tubed line stage. Your H/K receiver has the crucial preamp out/amp in feature that allows you to bypass completely the internal volume and tone control circuitry. By using the recording O/P to drive the tubed line stage, you retain use of the receiver's tuner, phono section, and selector switch.
A useful rule of thumb is that the amp/speaker combo should be capable of 102 dB. peaks. So, 1 W. = 90 dB., 2 W. = 93 dB., ..., and 16 W. = 103 dB. A 15 WPC amp seems indicated. Also, how is the SPL rating of your speakers specified? If they are 4 Ohm nominal and the rating is specified for a 2.83 V. drive, the true efficiency is 87 dB.
You could get the power you need from push/pull EL84s. SE amps above 8 WPC cost big bucks.
An option you might consider is the construction of a tubed line stage. Your H/K receiver has the crucial preamp out/amp in feature that allows you to bypass completely the internal volume and tone control circuitry. By using the recording O/P to drive the tubed line stage, you retain use of the receiver's tuner, phono section, and selector switch.
JBL! These rocks!
Seriously, I was in your predicament years ago. I bought an Infinity Kappa 200 (89dB) with SS amplification, but fell in love with my first SET amp - 2A3. My 2A3 can suprisingly drive my Kappa at loud levels for my cube (yeah, I have a square room- 4m x 4m). My low end HT uses a JBL LX2002 and to my delight, it can also be driven by the 2A3. Although I had an Anthem Amp 1 (40W) at that time, I still prefer the tone and speed of the 2A3.
However, when I tried other speakers, i.e., Monitor Audio that's supposed to be higher efficiency by a bit, it was a harder drive. I also tried a modern Klipsch RB-3 and I didn't like it.
My point is I can't rely on the published sensitivity. If you can borrow amplifiers from friends to try it out with your JBL, that would be best.
Having said that, I would say that something like a Dynaco ST-70 power level might just let it rock!
Seriously, I was in your predicament years ago. I bought an Infinity Kappa 200 (89dB) with SS amplification, but fell in love with my first SET amp - 2A3. My 2A3 can suprisingly drive my Kappa at loud levels for my cube (yeah, I have a square room- 4m x 4m). My low end HT uses a JBL LX2002 and to my delight, it can also be driven by the 2A3. Although I had an Anthem Amp 1 (40W) at that time, I still prefer the tone and speed of the 2A3.
However, when I tried other speakers, i.e., Monitor Audio that's supposed to be higher efficiency by a bit, it was a harder drive. I also tried a modern Klipsch RB-3 and I didn't like it.
My point is I can't rely on the published sensitivity. If you can borrow amplifiers from friends to try it out with your JBL, that would be best.
Having said that, I would say that something like a Dynaco ST-70 power level might just let it rock!
Wow, I never expected such an amazing respone, you guys are awesome!
you are exactly correct, and I am any highschooler, and want to have my music as loud as possible, however, I listen to stuff thats a little different, I personally love slamming down some hardcore, floor thomping Tony Bennett, and John Coltrane. However I am a big fan of The Who, Led Zeppelin, and Pink Floyd. I collect most everything on Vinyl (if i can find it) however thats off topic
I do once again find myself battling between PP and SE. do you think a PP el84 would be the way to go? i have 4 lying around (not exactly the bongs, and zig-zags one would expect from an average high-schooler) however two of them i pulled out of a hi-fi i bought at a thrift store. The problem i encounterd with PP was the sheer cost of the transformers! or am I mistaken? will SE be just as much for less power?
you are exactly correct, and I am any highschooler, and want to have my music as loud as possible, however, I listen to stuff thats a little different, I personally love slamming down some hardcore, floor thomping Tony Bennett, and John Coltrane. However I am a big fan of The Who, Led Zeppelin, and Pink Floyd. I collect most everything on Vinyl (if i can find it) however thats off topic
I do once again find myself battling between PP and SE. do you think a PP el84 would be the way to go? i have 4 lying around (not exactly the bongs, and zig-zags one would expect from an average high-schooler) however two of them i pulled out of a hi-fi i bought at a thrift store. The problem i encounterd with PP was the sheer cost of the transformers! or am I mistaken? will SE be just as much for less power?
alexmoose
My personal opinion would be to purchase an inexpensive SS amplifier and use this while saving up to purchase or build a tube amplifier. Transformers can be expensive depending on your taste. The "Good Iron" costs a good deal more than the cheap stuff and the payoff is better performance.
It would appear that you have the makings of a tube junkey. One should keep in mind the project that will be undertaken and plan accordingly for it. Its better (my opinion here) to build one good project than 3 or 4 that are so so.
My personal opinion would be to purchase an inexpensive SS amplifier and use this while saving up to purchase or build a tube amplifier. Transformers can be expensive depending on your taste. The "Good Iron" costs a good deal more than the cheap stuff and the payoff is better performance.
It would appear that you have the makings of a tube junkey. One should keep in mind the project that will be undertaken and plan accordingly for it. Its better (my opinion here) to build one good project than 3 or 4 that are so so.
Hi alexmoose,
If you want to listen to "my music" you will turn it up.
Joe has a good point, but I'd say assemble a P-P EL84 with what you can get a hold of. Your first amp will not be perfect (so - mine wasn't either). So build the first one and learn from your mistakes. It will make sound and it will be something you can be proud of.
Go for it!
-Chris
If you want to listen to "my music"
you will turn it up.Joe has a good point, but I'd say assemble a P-P EL84 with what you can get a hold of. Your first amp will not be perfect (so - mine wasn't either). So build the first one and learn from your mistakes. It will make sound and it will be something you can be proud of.
Go for it!
-Chris
No, I haven't tried them yet. I bought a lifetime supply of surplus P-P transformers that are useful for HiFi amps in the 30 to 50 watt range, and guitar amps in the 80 to 100 watt range. I was planning to buy a set of Edcors to try in my screen drive 6AV5 P-P amp, but the amp puts out way more power than I expected, and the surplus transformers are a perfect fit.
I plan to try the cheap Edcor P-P transformers in a P-P 6AQ5 amp, but that won't happen for a while.
anatech said:Hi alexmoose,
If you want to listen to "my music"
Joe has a good point, but I'd say assemble a P-P EL84 with what you can get a hold of. Your first amp will not be perfect (so - mine wasn't either). So build the first one and learn from your mistakes. It will make sound and it will be something you can be proud of.
Go for it!
-Chris
Wow, you're extreemly right I think maybe I got too mixed-up in wattage to think about whats really important, building something that works, something that I can switch from my ear-pounding SS amp to something that sounds a little different, a little sweeter. I think maybe I should just go for SE for its simplicity, and sheer braging rights among my nerdy, nerdy friends (amps beat the S*** out of computers)
No, you have it back-to-front! SE output transformers need a lot more iron in the core than PP, for the same power, because with SE there is a net DC flow in the OPT primary and this needs a core with an air-gap to avoid magnetic saturation. An air-gapped core gives much less inductance for its weight and so needs to be very big even to get modest inductance. Big core = big dollars!
PP trannies are easier to make, because there is no net DC current in the primary (provided that the OP tubes are well-balanced), therefore no need for an air-gap, so a smaller core can be used. So, PP OPTs are smaller and less expensive than SE trannies.
PP topology is generally easier to work with and is usually more efficient than SE, because PP enables you to use class AB1, giving you more watts output per tube. Also, with PP you can more readily apply negative feedback to reduce distortion and increase damping factor, for some nice, punchy bass!
Hi Ray,
I was stressing P-P because I didn't want to come out say what you just did, possibly attracting some lightning. Didn't feel like watching a fight.
I happen to agree with you and would stress that alexmoose takes this to heart. P-P can also be easier on the tubes since they may not be biased on as hard as a SET type. Your comments on transformers are exactly right as well.
Alexmoose, if you want cheap SET, get two old clock radios (the same) and use a 1:1 isolation power transformer to reconnect them as a stereo amp. You will have probably a pair of 50C5's and the transformers (on a cheap speaker). That should be good for a watt or two.
-Chris
I was stressing P-P because I didn't want to come out say what you just did, possibly attracting some lightning. Didn't feel like watching a fight.
I happen to agree with you and would stress that alexmoose takes this to heart. P-P can also be easier on the tubes since they may not be biased on as hard as a SET type. Your comments on transformers are exactly right as well.
Alexmoose, if you want cheap SET, get two old clock radios (the same) and use a 1:1 isolation power transformer to reconnect them as a stereo amp. You will have probably a pair of 50C5's and the transformers (on a cheap speaker). That should be good for a watt or two.
-Chris
Chris,
I am ready to face the slings and arrows of outraged even-order-harmonic buffs - er, SETsters. No offence, really!
Joking aside, not wishing to ruffle any feathers but it is easier to succeed with PP than with SET, especially for a relative newcomer to tubes - to build a PP amp and get it working and to find speakers that will sound OK with it.
I am ready to face the slings and arrows of outraged even-order-harmonic buffs - er, SETsters. No offence, really!
Joking aside, not wishing to ruffle any feathers but it is easier to succeed with PP than with SET, especially for a relative newcomer to tubes - to build a PP amp and get it working and to find speakers that will sound OK with it.
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