Hi all,
I recently decided that i want to build my very own first amp 🙂
Now choice is coming down to following designs..
1. Tube preAmp + Tube powerAmp in SE config
2. Tube preAmp + LM3886 powerAmp
I have finished my speakers, you can check details in pictures.
Currently its connected to 3.6w 6p6s SE tube amp, and it sounds great, but i would like something with little bit more power. My goal is around 20-30w per channel.
Any recommendations and/or schematics ?
*NOTE*
Im a total noob when it comes to this, i have some very basic knowledge and soldering ability, so i apologize in advance for stupid questions.
I recently decided that i want to build my very own first amp 🙂
Now choice is coming down to following designs..
1. Tube preAmp + Tube powerAmp in SE config
2. Tube preAmp + LM3886 powerAmp
I have finished my speakers, you can check details in pictures.
Currently its connected to 3.6w 6p6s SE tube amp, and it sounds great, but i would like something with little bit more power. My goal is around 20-30w per channel.
Any recommendations and/or schematics ?
*NOTE*
Im a total noob when it comes to this, i have some very basic knowledge and soldering ability, so i apologize in advance for stupid questions.
Attachments
Any specific reason in terms of sound characteristic? Bass? Distortion at listening volume? Clarity in the trebles?
I take it that the LM3886 would be running in class A?
One option could be Tom Christian's Taming the LM3886 Chip Amplifier – Neurochrome
I take it that the LM3886 would be running in class A?
One option could be Tom Christian's Taming the LM3886 Chip Amplifier – Neurochrome
I would like class A, yes. I like how it sounds, at least in my current tube amp.
As for characteristic:
Something that my current amp offers me, which is clarity, depth, details and most important, lack of distortion. But with ability to push some more power out of it 🙂
If something is missing in current setup i would say its a punchy bass, there is plenty of bass, and some more, due to huge cabinet and 15" driver, but when i first tested on class AB Kenwood amp, bass sounded more punchy, but everything else was worse.
Reason i would like hybrid design, is that the more i read and watch videos about amps, everything suggests that most of sound characteristics comes from preamp anyway, so in my head, then its better to go with chips on power stage, more reliable and robust, but then again, im still open to tube power stage, tho im little bit concerned with longevity of it.
But again, since i dont know anything, i might be wrong 🙂
To get 20W, you will need to parallel tubes for a SE amp. To get good sound from a LM3886, you will need a good power supply designs and some amp building experiences. Neither solution is a good choice for newbie. IMHO, it is better to lower expectation to either 6W or a push pull design as suggested above.
I'll suggest third option...
Solid state preamp feeding push / pull tube output. Some EL34's or KT88's should do 30w just fine. Many schematics and resources posted here from members-
Reason for solid state preamp is that it's much easier for newbies (like me) to design with less possibility of 'hum' background from tube preamps.
Jim
Solid state preamp feeding push / pull tube output. Some EL34's or KT88's should do 30w just fine. Many schematics and resources posted here from members-
Reason for solid state preamp is that it's much easier for newbies (like me) to design with less possibility of 'hum' background from tube preamps.
Jim
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Ok, so after some thoughts, if i decide on classic SE class A with tube preamp and power amp, with single pair of tubes, how much amplification can i get from various tubes ? I was trying to see some comparison chart or something.. but cant find anything that compares popular tubes
el34, el84, b300, 6v6...
Also back to solidstate, i saw that LM3886 doesnt need preamp ? So in a sense, a a single LM3886 can do everything. I saw some designs floating that support se class a design of this chip, also some gainclone, but i have no idea what it is.
I guess i could live with push pull in class A ? Its bit strange to me how can push pull work in class A to begin with, since class A amp's a full cycle... isnt the idea of push pull that each amp amps 180, so half a cycle...
el34, el84, b300, 6v6...
Also back to solidstate, i saw that LM3886 doesnt need preamp ? So in a sense, a a single LM3886 can do everything. I saw some designs floating that support se class a design of this chip, also some gainclone, but i have no idea what it is.
I guess i could live with push pull in class A ? Its bit strange to me how can push pull work in class A to begin with, since class A amp's a full cycle... isnt the idea of push pull that each amp amps 180, so half a cycle...
1. Take from me - the path of designing an amplifier from scratch is long, tortured and there be dragons down there.
2. Push pull can work in class A. The bias is increased so that both tubes work with the waveform being above the zero transition. The down side is that both your tubes are working with less maximum swing thus less power results. There's also class AB.. and other such wonders like hybrids AB+G for example.
Most established designs will switch to class A or AB using push pull through a transformer depending on the power required.
PP cancels even harmonics so it will sound different (colder perhaps) than your SE. Add to the fact that controlling bass reduces that fatter bottom register of sound but inreality it will be taught and possibly leaner sounding. For good sound and bottom end you cannot skimp on the output transformers and their size or the power supply..
The danger here is paralysis by analysis - so perhaps you can get to listen to a PP amp or solid state power with a tube pre (or vice versa) before you make the leap. In terms of amplification - it becomes a budget and a how complex is bad question. Tube amps ARE more expensive than solid state amps and most of that comes down to there is less demand for high voltage iron compared to solid state operating at lower voltages.
In an amplification chain, the normal approach is to maximise the first amplification stage which is why people say the pre-amp makes the most difference. Most of the time the backend power stage is simply converting large voltage swing to current. So tube pre and solid state backend may offer the cheapest and most effective route for a Big Bang for your buck. However in DIY.. there's lots of options to suit budget and desire.
2. Push pull can work in class A. The bias is increased so that both tubes work with the waveform being above the zero transition. The down side is that both your tubes are working with less maximum swing thus less power results. There's also class AB.. and other such wonders like hybrids AB+G for example.
Most established designs will switch to class A or AB using push pull through a transformer depending on the power required.
PP cancels even harmonics so it will sound different (colder perhaps) than your SE. Add to the fact that controlling bass reduces that fatter bottom register of sound but inreality it will be taught and possibly leaner sounding. For good sound and bottom end you cannot skimp on the output transformers and their size or the power supply..
The danger here is paralysis by analysis - so perhaps you can get to listen to a PP amp or solid state power with a tube pre (or vice versa) before you make the leap. In terms of amplification - it becomes a budget and a how complex is bad question. Tube amps ARE more expensive than solid state amps and most of that comes down to there is less demand for high voltage iron compared to solid state operating at lower voltages.
In an amplification chain, the normal approach is to maximise the first amplification stage which is why people say the pre-amp makes the most difference. Most of the time the backend power stage is simply converting large voltage swing to current. So tube pre and solid state backend may offer the cheapest and most effective route for a Big Bang for your buck. However in DIY.. there's lots of options to suit budget and desire.
I was kinda expecting that once you open that Pandora's box, there is no turning back 🙂 At this moment, i dont think i possess the knowledge to do it on my own. I was hoping more of, i present what i need, and someone will come with some schematic that works or point me at right direction 🙂
Regarding PP and SE, i own 3 amps, 2x SS PP class AB and 1x SE class A tube. I dont know, but i swear i can always hear some subtle distortion with PP class AB, especially in mid-high range.
Going back to my tube amp, will replacing tube maybe help bring it to life ? tubes in that amp are pretty old, from 80's, i have no idea how much they were used and how much wear they have. I can grab pair of 6p6s for around 20-50 bucks, is it worth trying to replace them first and see if bass response improves ?
Here is the link of previous thread regarding tube amp i own, you can see it on later pages Help chosing second hand tube amp for 95db speakers
Also, on one note, i was using my fiio k5 pro dac as line out.
From what i can see it has 2Vrms lineout, is this compatible with my current tube amp ? Line in on amp is 20k alps pot and feeds into ECC82 preamp tube.
Here are the specs of DAC
From what i can see it has 2Vrms lineout, is this compatible with my current tube amp ? Line in on amp is 20k alps pot and feeds into ECC82 preamp tube.
Here are the specs of DAC
General results FiiO K5 Pro
Channel
Center/Summary
Variation in frequency response in band from 100 Hz to 10 kHz, dB
-0,09, 0,02
Max voltage output at 0 dBFS, VRMS
1,98
Max voltage output at 0 dBFS, dBV
5,92
Max voltage output at 0 dBFS, dBu
8,14
Harmonic distortion at 0,0 dBFS @ 1 kHz, dB
-82,5
Total harmonic distortion at 0,0 dBFS @ 1 kHz, %
0,007519
Harmonic distortion at -3,0 dBFS @ 1 kHz, dB
-84,6
Total harmonic distortion at -3,0 dBFS @ 1 kHz, %
0,005869
Channel
Center/Summary
Variation in frequency response in band from 100 Hz to 10 kHz, dB
-0,09, 0,02
Max voltage output at 0 dBFS, VRMS
1,98
Max voltage output at 0 dBFS, dBV
5,92
Max voltage output at 0 dBFS, dBu
8,14
Harmonic distortion at 0,0 dBFS @ 1 kHz, dB
-82,5
Total harmonic distortion at 0,0 dBFS @ 1 kHz, %
0,007519
Harmonic distortion at -3,0 dBFS @ 1 kHz, dB
-84,6
Total harmonic distortion at -3,0 dBFS @ 1 kHz, %
0,005869
Soo.. is there any guide/schematic for Class A; SE amp with either single or parallel tubes ? 5w or more ? I really dont know where to start..
I think now you know you want Class A SE with 5-10W, the question is more which kit or schematic would suit my requirements.
I have spent about 2 years learning and I can just about scratch together a decent design for OTLs (output transformers - well I'm lost, and that interaction between parallel tubes and OTs is where you will need a considerable amount of help).
There's a great thread about a schematic collection from Japan. It may be worth checking if there's already an example designs that can drive 5-10W of SE. Then perhaps read and narrow down the designs based on the tube requirements. You may find, as quietly suggested, the majority of those amps you discover will be push pull of some description.
After all 100+ years of millions of people tweaking designs and ideas - there's probably a reason that designs for SE start becoming scarce at high power (or become scary - which is not for the inexperienced).
One option is to look at the vendors for tube kits in the subforms. At least you have an active forum as you do your first kit build. I notice that some have ~10W SE designs but consider that most marketing teams quote this but in reality (as shown by Steph in her great skunky designs YT series) they aren't likely todo that without unlistenable distortion, 1/2 the amount may be more reasonable. Once you have found a design - study it. learn why they're doing things, then you will understand (and it will be a vertical learning curve) more for what you really want.
With all credit to the forum (and there is a considerable amount of expertise), the onus is on you to start from the beginning and get to the end - that may mean a few dead ends that cause you to return to the drawing board. People will chime in with guidance or observations but you need to have demonstrated and done the footwork. Almost like people here are in for the journey.. each time they make a new amp 🙂
I have spent about 2 years learning and I can just about scratch together a decent design for OTLs (output transformers - well I'm lost, and that interaction between parallel tubes and OTs is where you will need a considerable amount of help).
There's a great thread about a schematic collection from Japan. It may be worth checking if there's already an example designs that can drive 5-10W of SE. Then perhaps read and narrow down the designs based on the tube requirements. You may find, as quietly suggested, the majority of those amps you discover will be push pull of some description.
After all 100+ years of millions of people tweaking designs and ideas - there's probably a reason that designs for SE start becoming scarce at high power (or become scary - which is not for the inexperienced).
One option is to look at the vendors for tube kits in the subforms. At least you have an active forum as you do your first kit build. I notice that some have ~10W SE designs but consider that most marketing teams quote this but in reality (as shown by Steph in her great skunky designs YT series) they aren't likely todo that without unlistenable distortion, 1/2 the amount may be more reasonable. Once you have found a design - study it. learn why they're doing things, then you will understand (and it will be a vertical learning curve) more for what you really want.
With all credit to the forum (and there is a considerable amount of expertise), the onus is on you to start from the beginning and get to the end - that may mean a few dead ends that cause you to return to the drawing board. People will chime in with guidance or observations but you need to have demonstrated and done the footwork. Almost like people here are in for the journey.. each time they make a new amp 🙂
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Joined 2009
Paid Member
After perusing and reading this forum for over a decade and building a few amps myself I'd recommend the following combination for a HYBRID,
Tube pre-amp: for 7W(rms) into an 8 Ohm speaker you'll want at least a 10 volt peak-to-peak swing. If you have a modern source such as a CD player you'll have no trouble doing this if your pre-amp can give you a gain of at least 5x. And for that I recommend the simple 6V6 which has been immortalized by Salas,
6V6 line preamp
Simple solid state power amp: SEWA
SEWA - Seven Watt Amplifier
some observations made by somebody who built SEWA and posted it into that thread somewhere:
Wow, nice one Bigun, that is exactly what i wanted. Now the hard part of fusing these two together, and i can see in SEWA thread alot of schematics floating around, guess i will have to find the right one 🙂
That's because the external dongle is a USB DAC. Even apple's power supply has as chip in the mag connector for interacting with the laptop and a processor in the SMPS to switch the power requirements differences between the MacBookPro and MacBook.
To be honest, this DAC is nothing special, i just liked its design and its many i/o ports. I didnt want a desktop pc laying there, so i opted for a external dac, rather than a soundcard for PC (even tho in my pc i have Creative eXtreme Music card, which has awesome dac on it)
Main reason i posted it, i was concerned if its lineout voltage is too much for ecc82 preamp on my current amp.
No problem man, i get what you guys are trying to say to me, that i should start with something much easier etc... and its a valid point since i have no idea what im doing 😀
It going to be some time before i start this project, busy with learning some new programs for work, bit hard to learn few things at the same time 🙂 Probably going to start a new dedicated thread for it, since this one is just for suggestions etc...
Ok i changed my mind once again, now im 99% thinking this build
Babelfish M25 R.2/SET amp
PRO's
+ Guy selling kit is my countryman, so easy communication/support from his side
+ everything is local
+ very linear with minimal THD
+ modular design, minimal work required from my side, which is biggest plus
+ decent output considering class A, 20W @8R
CON's
- Bit expensive, looking around 500-600e for kit + trafo's + chassis
- Requires preamp, but builder say i can get away with 2v from my DAC line output
Tho there are two versions he is offering, M25 and SET, M25 being more linear, while SET having bit more "fattness" to it ? i dont really know, which one would sit better with my speakers.
Guess now this becomes irrelevant for tube forum 🙂
Babelfish M25 R.2/SET amp
PRO's
+ Guy selling kit is my countryman, so easy communication/support from his side
+ everything is local
+ very linear with minimal THD
+ modular design, minimal work required from my side, which is biggest plus
+ decent output considering class A, 20W @8R
CON's
- Bit expensive, looking around 500-600e for kit + trafo's + chassis
- Requires preamp, but builder say i can get away with 2v from my DAC line output
Tho there are two versions he is offering, M25 and SET, M25 being more linear, while SET having bit more "fattness" to it ? i dont really know, which one would sit better with my speakers.
Guess now this becomes irrelevant for tube forum 🙂