300B SEs are in some ways very nice, eg to my ears perfect for choral pieces; but I’m mostly a rock listener.
I don’t want distortion or sand, I want to build a tube amp with three priorities:
Great dynamics in drumming and other transients, effortless power and just a little richness.
I recently heard this muscular sound in a commercial 845 SE (using I believe custom Stevens & Billington trannies), but it’s outside my price range.
I’m new to DIY so 1200 volts is not a good idea now; and even if it were, the parts cost of a good 845 (or 211) is high!
What gave the 845 an effortless powerful sound, is it:
- just the higher watts (but it’s only about double ie 3 dB over a 300B),
- the higher volts – I doubt it,
- the ratio of amp power to speaker sensitivity (an 18 watt amp driving 90 db speakers) – I don’t think so
- something about the tubes (Shuguang 845Bs) – possibly
- generous power supply capacitance - maybe
- good OPTs - quite possibly
Some of the above plus others – probably – but which to focus on and do?
So I thought, when driving 98 dB speakers (G ribbons and PHL 3451s), it should be possible to do a 300B SE at a lower cost than an 845, that still has an effortless powerful sound. More ballsy and kicking with some smoothness than angelic. Maybe 33-50% lower cost, maximum say roughly US$ 750.
Ultra wide bandwidth not needed (using subs below 100 Hz, and I can’t hear over 14 kHz). This should make it easier to get dynamics.
Suggestions please:
- Which 300B tubes and parts, esp OPTs? Maybe James or Bartolucci.
- What circuit?
- Likely to be using Aikido line stage - only 2-stages strongly preferred.
- Use 2A3s as driver tubes?
- Use interstage trannies?
- Parallel-feed??
- What PS?
KR’s 300BXLS is powerful, Steve Rochlin liked it, but mixed other opinions. I just learnt of KR’s 842HVD; apparently in a Cary 805C they provide “more punch and better bass” - but $500/ matched pair – extra cost of both is not justified for what I’m after ditto!
I don’t want to pay double for tubes, so as to allow money for really good iron.
* What not to do?
Thanks
I don’t want distortion or sand, I want to build a tube amp with three priorities:
Great dynamics in drumming and other transients, effortless power and just a little richness.
I recently heard this muscular sound in a commercial 845 SE (using I believe custom Stevens & Billington trannies), but it’s outside my price range.
I’m new to DIY so 1200 volts is not a good idea now; and even if it were, the parts cost of a good 845 (or 211) is high!
What gave the 845 an effortless powerful sound, is it:
- just the higher watts (but it’s only about double ie 3 dB over a 300B),
- the higher volts – I doubt it,
- the ratio of amp power to speaker sensitivity (an 18 watt amp driving 90 db speakers) – I don’t think so
- something about the tubes (Shuguang 845Bs) – possibly
- generous power supply capacitance - maybe
- good OPTs - quite possibly
Some of the above plus others – probably – but which to focus on and do?
So I thought, when driving 98 dB speakers (G ribbons and PHL 3451s), it should be possible to do a 300B SE at a lower cost than an 845, that still has an effortless powerful sound. More ballsy and kicking with some smoothness than angelic. Maybe 33-50% lower cost, maximum say roughly US$ 750.
Ultra wide bandwidth not needed (using subs below 100 Hz, and I can’t hear over 14 kHz). This should make it easier to get dynamics.
Suggestions please:
- Which 300B tubes and parts, esp OPTs? Maybe James or Bartolucci.
- What circuit?
- Likely to be using Aikido line stage - only 2-stages strongly preferred.
- Use 2A3s as driver tubes?
- Use interstage trannies?
- Parallel-feed??
- What PS?
KR’s 300BXLS is powerful, Steve Rochlin liked it, but mixed other opinions. I just learnt of KR’s 842HVD; apparently in a Cary 805C they provide “more punch and better bass” - but $500/ matched pair – extra cost of both is not justified for what I’m after ditto!
I don’t want to pay double for tubes, so as to allow money for really good iron.
* What not to do?
Thanks
I have built several amps over the past 40 years both tube and solid state. Even though I listen to a wide variety of music, 2/3 of my CD and 90% of my records are rock and I like it LOUD. I have a 300B SE amp and an 845SE amp and a 300B push pull amp. All are zero feedback designs. I am very economy minded in my amp construction, so all of the output tubes are Shuguang, and the transformers are nothing special, with the exception of the Electra prints in the 300B. I currently have all three amps set up so that swapping is a one minute operation.
I find that the transient response that you seek flows effortlessly from the 300B push pull amp. In fact this is my favorite amp to use for highly dynamic music like techno. When the drummer whacks the rim of the snare with the stick the shot shoots right through your head. It has the strongest bass of the 3 amps. It also does Jimi at full volume quite well. Good for Van Halen, Metallica and other LOUD music.
The 845 SE is not as "in your face" as the 300B push pull. It is best for less dynamic and more vocal music. It does Jimi quite well. I use it for Moody Blues, Fleetwood Mac, and similar music.
The 300B SE is the most detailed of the three amps. It will bring out subtle details thet the other amps miss. It is set up to use a variety of output tubes, and has the best sound with 45's, but only 2 watts per channel.
I believe that the "in your face" bass of the push pull amp is a function of the amps output impedance. This in influenced by a number of factors, including most of the items that you mentioned. Tubes, output transformers, circuit design, power supply, and choice of load impedance.
I would advise you to listen to a 300B pudh pull amp, if possible before making your final decision. I have been searching for a single amp design that incorporates the best aspects of all three amplifiers, but it has eluded me so far. I have prototyped an 833A amp with over 100 watts and this might be it.
See the web page for more details:
http://www.tubelab.com/
I find that the transient response that you seek flows effortlessly from the 300B push pull amp. In fact this is my favorite amp to use for highly dynamic music like techno. When the drummer whacks the rim of the snare with the stick the shot shoots right through your head. It has the strongest bass of the 3 amps. It also does Jimi at full volume quite well. Good for Van Halen, Metallica and other LOUD music.
The 845 SE is not as "in your face" as the 300B push pull. It is best for less dynamic and more vocal music. It does Jimi quite well. I use it for Moody Blues, Fleetwood Mac, and similar music.
The 300B SE is the most detailed of the three amps. It will bring out subtle details thet the other amps miss. It is set up to use a variety of output tubes, and has the best sound with 45's, but only 2 watts per channel.
I believe that the "in your face" bass of the push pull amp is a function of the amps output impedance. This in influenced by a number of factors, including most of the items that you mentioned. Tubes, output transformers, circuit design, power supply, and choice of load impedance.
I would advise you to listen to a 300B pudh pull amp, if possible before making your final decision. I have been searching for a single amp design that incorporates the best aspects of all three amplifiers, but it has eluded me so far. I have prototyped an 833A amp with over 100 watts and this might be it.
See the web page for more details:
http://www.tubelab.com/
Well... you force me to toot my own horn....
My 300B amp is within that price range. I also listen to rock, and wide dynamic range classical (Beethoven. The original rocker!), and everything in between.
What do I use to get the good dynamics and wide freq response? Beefy power supply, solid state rectification, large filter capacitance (330 uF) and One Electron OPT. If you are going to spend 90 bucks apiece for the Hammond, you would be better off with the One Electrons for a few dollars more. Literally about 95 bucks apiece. Oh, I use cheap 59 dollar Chinese 300Bs. Sound is amazing. JJ/Teslas for 90 bucks each should be phenominal. I may treat myself to those in a couple of weeks.
In my 300B amp (pictured upper left corner) I use a 300 volts 250 mA transformer. If you can find one with more current, use it. I use solid state rectification for three reasons, 1 the recovery is much quicker for dynamics. 2 The drop is only about 2 volts for maximum B+. 3 I use the 5 volts which would normally be used for the tube rectifier for the 300Bs.
This amp has been the talk of the "Oswalds Mill Tube Tasting" for years. Last year I did a proof of concept for my design and played, while they played soft chamber music and blues, Boston's "Foreplay/Long Time". It blew everyone's mind (including mine!) how it sounded great without breaking up. BTW, I play it on speakers that are about 86dB efficiency, and it was my 4.5 watt prototype... But the speakers at the Mill are I believe 98dB horns. My production kits have a 350 volt power transrformer for 7-8 watt output (the B+ is about 380 volts).
The issue here... I would not be easily inclined to share the schematic. Sorry. But with these ideas, you can make a pair of mono blocks for yourself. My amp is a stereo and the way I have designed it gives it its unique tonal character, and deep strong bass. All with no NFB.
I also use the 12AT7 for preamp/driver. One half is a simple preamp, gain of about 20, and the second half is a directly connected cathode follower delivering about 3-4 mA for the signal, if the tube really needs that much. But the follower keeps the preamp at its full gain for maximum output. The only caveat there is that you may need to experiment with different brands of 12AT7. I use the Phillips NOS. I recently bought a pair of JJ/Tesla, which normally sound terrific to me, and heard some IM distortion. That is a negative to me when not using NFB. Of course, they may have needed tim e to break in.
Hope this helps!
Gabe
My 300B amp is within that price range. I also listen to rock, and wide dynamic range classical (Beethoven. The original rocker!), and everything in between.
What do I use to get the good dynamics and wide freq response? Beefy power supply, solid state rectification, large filter capacitance (330 uF) and One Electron OPT. If you are going to spend 90 bucks apiece for the Hammond, you would be better off with the One Electrons for a few dollars more. Literally about 95 bucks apiece. Oh, I use cheap 59 dollar Chinese 300Bs. Sound is amazing. JJ/Teslas for 90 bucks each should be phenominal. I may treat myself to those in a couple of weeks.
In my 300B amp (pictured upper left corner) I use a 300 volts 250 mA transformer. If you can find one with more current, use it. I use solid state rectification for three reasons, 1 the recovery is much quicker for dynamics. 2 The drop is only about 2 volts for maximum B+. 3 I use the 5 volts which would normally be used for the tube rectifier for the 300Bs.
This amp has been the talk of the "Oswalds Mill Tube Tasting" for years. Last year I did a proof of concept for my design and played, while they played soft chamber music and blues, Boston's "Foreplay/Long Time". It blew everyone's mind (including mine!) how it sounded great without breaking up. BTW, I play it on speakers that are about 86dB efficiency, and it was my 4.5 watt prototype... But the speakers at the Mill are I believe 98dB horns. My production kits have a 350 volt power transrformer for 7-8 watt output (the B+ is about 380 volts).
The issue here... I would not be easily inclined to share the schematic. Sorry. But with these ideas, you can make a pair of mono blocks for yourself. My amp is a stereo and the way I have designed it gives it its unique tonal character, and deep strong bass. All with no NFB.
I also use the 12AT7 for preamp/driver. One half is a simple preamp, gain of about 20, and the second half is a directly connected cathode follower delivering about 3-4 mA for the signal, if the tube really needs that much. But the follower keeps the preamp at its full gain for maximum output. The only caveat there is that you may need to experiment with different brands of 12AT7. I use the Phillips NOS. I recently bought a pair of JJ/Tesla, which normally sound terrific to me, and heard some IM distortion. That is a negative to me when not using NFB. Of course, they may have needed tim e to break in.
Hope this helps!
Gabe
kmtang
Any Audio Note should sound pretty good. But I’ve heard mixed reports about parallel SE amps – often not quite the SE magic.
And AN’s ‘base’ 300B SE alone is US 1400, way over budget.
Apart from about 845 SE power, any reason you suggested this?
tubelab
An interesting comparison. I’ll try to locate a local 300B push pull.
Using subs below 100 Hz, only the upper bass matters.
I guess a 300B PP would cost more than a 300B SE – extra tube, cheaper OPTs, more parts – how much more, and how much in total?
I imagine your 833A could be a BMW M5 of an amp .
As a reference, which might have more of that ‘magic’ sound do you think – a 300B PP, or say a 30 watt (SE) Aleph SS??
So far most of the focus has been on other topologies. Apart from Gabe -
Solid state rectification - if recovery is quicker for dynamics -would be better.
“B+ is about 380 volts” vs 450 volts - is that for longer life?
12AT7 for preamp/driver. Your emphasis appears to be best value.
Your kit is $750, I was intending to spend about that on parts eg really good OPTs.
I’ve heard that to make an 845 sound like a 300b, drive it with a 300b:
* What driver for a 300b would give it most drive?
* What about a 6550 driver in triode mode connection, and a 6C45PiE upfront?
Anyone from the scratch building 300B SE circles – who’s built a 300b that really rocked?
Any Audio Note should sound pretty good. But I’ve heard mixed reports about parallel SE amps – often not quite the SE magic.
And AN’s ‘base’ 300B SE alone is US 1400, way over budget.
Apart from about 845 SE power, any reason you suggested this?
tubelab
An interesting comparison. I’ll try to locate a local 300B push pull.
Using subs below 100 Hz, only the upper bass matters.
I guess a 300B PP would cost more than a 300B SE – extra tube, cheaper OPTs, more parts – how much more, and how much in total?
I imagine your 833A could be a BMW M5 of an amp .
As a reference, which might have more of that ‘magic’ sound do you think – a 300B PP, or say a 30 watt (SE) Aleph SS??
So far most of the focus has been on other topologies. Apart from Gabe -
Solid state rectification - if recovery is quicker for dynamics -would be better.
“B+ is about 380 volts” vs 450 volts - is that for longer life?
12AT7 for preamp/driver. Your emphasis appears to be best value.
Your kit is $750, I was intending to spend about that on parts eg really good OPTs.
I’ve heard that to make an 845 sound like a 300b, drive it with a 300b:
* What driver for a 300b would give it most drive?
* What about a 6550 driver in triode mode connection, and a 6C45PiE upfront?
Anyone from the scratch building 300B SE circles – who’s built a 300b that really rocked?
Hearing is believing
Different amps would have different characters. I built 300B, 2A3, and 45 SE amps myself. I tried using different driver in the 2A3 amp. I also tried employ different types of capacitor for the bypass of the power supply.
Therefore, it is fun being a DIYer who can experience various circuitries/components and find out the which one suits your taste.
Lastly, I would say there's no such thing is perfect in this world. This would be an endless game seeking for the perfection.
Different amps would have different characters. I built 300B, 2A3, and 45 SE amps myself. I tried using different driver in the 2A3 amp. I also tried employ different types of capacitor for the bypass of the power supply.
Therefore, it is fun being a DIYer who can experience various circuitries/components and find out the which one suits your taste.
Lastly, I would say there's no such thing is perfect in this world. This would be an endless game seeking for the perfection.
I really hate to be boring, but just go with the Allen Wright PP1C (fits all your criteria and cheap to build too) and add a CCS in the tail of the ouputs if preferred. Excellent performance and if you really want the 2H you can tweak the balance of the front end to get it. Just do a better PSU than Allen's.
It seems 300B SE builders don’t require muscle?
I guess a schematic of Allen Wright's all-differential, all-Class A DPA-300B might require industrial espionage in Switzerland. (A few years back Dan Marshall on the Joe List was working on an all differential, completely transformer coupled stereo PP 6B4G amplifier, but I don't brlieve published).
Anyone know of any other all-differential, all-Class A audio amps?
Brett
Not boring, and cheap, and a CCS should be good.
But a PP EL 34? It has the power, so it could have the effortless feel.
Still taking in this further lateral thinking.
> Just do a better PSU than Allen's.
What do you suggest?
Thanks
I guess a schematic of Allen Wright's all-differential, all-Class A DPA-300B might require industrial espionage in Switzerland. (A few years back Dan Marshall on the Joe List was working on an all differential, completely transformer coupled stereo PP 6B4G amplifier, but I don't brlieve published).
Anyone know of any other all-differential, all-Class A audio amps?
Brett
Not boring, and cheap, and a CCS should be good.
But a PP EL 34? It has the power, so it could have the effortless feel.
Still taking in this further lateral thinking.
> Just do a better PSU than Allen's.
What do you suggest?
Thanks
http://www.rintelen.ch/pdf/DIY/Igor.pdfrick57 said:
Depending upon the voltages you choose to run it at (I like 6550/KT88 hot and low over most EL34 setups) you could set it up using your choice of multi tubes and change it to 300Bs later if you chose with not too much effort.
For O/P stage CCS, go with a Pimm or similar
I found large performance gains in this amp with FW 6CJ3, LCLC, all motor run caps and a superreg or simple CCS-> stacked oc3's controlling the front end. I messed around with different powertrans to get the op points I like too. Spend some time in PSUD2. I usually don't bother with dual mono supplies either anymore.
MUCH larger, heavier and more expensive to build than the original though.
Thanks for the link to Christian Rintelen’s Igor 300B PP.
I’d avoided 300B PPs because of the extra cost. I guess you’d need at least US 1500 to do it properly, about twice my target. May be a project for down the track.
> I like 6550/ KT88 hot and low over most EL34 setups. You could set it up using your choice of multi tubes and change it to 300Bs later if you chose with not too much effort.
For O/P stage CCS, go with a Pimm or similar
Sounding more appealing . .
> I found large performance gains in this amp with FW 6CJ3, LCLC, all motor run caps and a superreg or simple CCS-> stacked oc3's controlling the front end
What were the gains in – bass extension/ dynamics/ overall clarity . . ?
I really like the idea of GM70s. I suspect that would cost even more than a 300 B PP?
Thanks
I’d avoided 300B PPs because of the extra cost. I guess you’d need at least US 1500 to do it properly, about twice my target. May be a project for down the track.
> I like 6550/ KT88 hot and low over most EL34 setups. You could set it up using your choice of multi tubes and change it to 300Bs later if you chose with not too much effort.
For O/P stage CCS, go with a Pimm or similar
Sounding more appealing . .
> I found large performance gains in this amp with FW 6CJ3, LCLC, all motor run caps and a superreg or simple CCS-> stacked oc3's controlling the front end
What were the gains in – bass extension/ dynamics/ overall clarity . . ?
I really like the idea of GM70s. I suspect that would cost even more than a 300 B PP?
Thanks
No, yes, no. Better in all regards. I used the existing PSU and driver from the AW amp and added the PSU for the GM70's. Later I went to big pentode drivers for even more improvement.rick57 said:
Never heard an SE amp that I thought was great.
No idea. I buy surplus iron and find uses for it, and big power trans etc can be very cheap secondhand as few people build high voltage projects.
More like 800+rick57 said:
Can't say for 211's, but for 845's, 813T's and GM7o's that's utter c*r*a*p.
Attached.
All other aspects of the design I had are from memory as it's been packed up for quite a while. Due to severe space limitations in this house, I've been tube ampless for >2 years, except for the MI stuff I build for customers.
My 300B push - pull amp cost me under $300 USD to build. Like Brett I find surplus iron and then build an amp for it. In this case I bought a truckload of push - pull OPT's when the guitar amp company ADA went out of buisness. I used them in the 300Beast, and in many other projects. I have tried several other transformers (including some UTC's and other expensive iron) in this amp and I keep putting back the surplus units. The transformers were 6600 ohm CT units made for 6L6's. Other PP transformers worked well in this amp. The UTC's were too bright for my speakers.
For power transformer I used a 300VA toroid that has 2X 175 volt AC secondary windings. put them in series, then use a SS bridge and a choke input filter with a LARGE cap. The rest of the schematic can be found in Vacuum Tube Valley #12. I used 6CG7's instead of 6SN7's because I have lots of them, and I find most 6SN7's to be microphonic. I used the simple power supply because I had the transformer.
If you decide to build a big SE amp, the secret in power transformers is to find an " industrial control transformer" these are intended to step 480 volts (they come in other voltages) down to 120 or 240 volts. Hook them up backwards and they turn 120 or 240 volts into 480 volts AC. A SS bridge gives 450 to 500 volts with a choke input and over 600 volts with a cap input. I use a voltage doubler made with 5AR4's to get 1100 volts. These transformers can often be found surplus for less than the shipping cost. I paid $20 FOR A 1KVA transformer. These transformers are rated in VA's, get a bigger one than you need, they sound better, due to improved regulation.
For power transformer I used a 300VA toroid that has 2X 175 volt AC secondary windings. put them in series, then use a SS bridge and a choke input filter with a LARGE cap. The rest of the schematic can be found in Vacuum Tube Valley #12. I used 6CG7's instead of 6SN7's because I have lots of them, and I find most 6SN7's to be microphonic. I used the simple power supply because I had the transformer.
If you decide to build a big SE amp, the secret in power transformers is to find an " industrial control transformer" these are intended to step 480 volts (they come in other voltages) down to 120 or 240 volts. Hook them up backwards and they turn 120 or 240 volts into 480 volts AC. A SS bridge gives 450 to 500 volts with a choke input and over 600 volts with a cap input. I use a voltage doubler made with 5AR4's to get 1100 volts. These transformers can often be found surplus for less than the shipping cost. I paid $20 FOR A 1KVA transformer. These transformers are rated in VA's, get a bigger one than you need, they sound better, due to improved regulation.
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