Next Amp: 2a3PSE, 300B or KT88SE UL
I know this may be like asking what’s better, Fords or Chevy, but here goes.
I’m in the planning stage of my 2nd amp and could use some input as to the choice of power tubes.
The first amp is a 2A3 SE…. I like the sound.
Most of the time the music I listen to are vocals, then jazz, and a little classical.
Just thinking of options for the next project:
1. 2A3 push-pull
2. 2A3 parallel single ended
3. 300B
4. KT88 SE ultra linear
The reasons I have the KT88 on the list:
1. low cost
2. I love the looks of that tube
3. This ultra linear looks interesting
Any thoughts?
I know this may be like asking what’s better, Fords or Chevy, but here goes.
I’m in the planning stage of my 2nd amp and could use some input as to the choice of power tubes.
The first amp is a 2A3 SE…. I like the sound.
Most of the time the music I listen to are vocals, then jazz, and a little classical.
Just thinking of options for the next project:
1. 2A3 push-pull
2. 2A3 parallel single ended
3. 300B
4. KT88 SE ultra linear
The reasons I have the KT88 on the list:
1. low cost
2. I love the looks of that tube
3. This ultra linear looks interesting
Any thoughts?
I'm deducing from your choices that you'd like a bit more power. If you want to join me for a thread, the next amp I want to build is an all-DHT PP2a3 one. I've stuck with PP as a topology, and I'm just moving up the sonic ladder with the choice of tubes. I'm guessing the end of the road is something like 26 into 71a into 2a3. 26 could be swapped with a 12a, and 71a with a 46. anything like that. I intend balanced all through, with diff pairs and CCSs underneath. Cap coupled with teflon caps.
The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now. Certainly a complex power supply, with chokes, polypropylene PSU caps etc. So likely to be two monos.
You haven't included the 845 - a low power (450v) PP amp with these would be good too. I think after the 2a3s you'd be disappointed with both KT88s and ultralinear. I'm personally going with 2a3 and/or 845 because they're cheap in basic Sovtek or Chinese flavour, and I prefer a thinner more focussed sound than the usual 300b amp.
Depends what sonic flavour you like - big and warm or clean and precise. Also speakers, source equipment, room size, listening material etc - what are they?
The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now. Certainly a complex power supply, with chokes, polypropylene PSU caps etc. So likely to be two monos.
You haven't included the 845 - a low power (450v) PP amp with these would be good too. I think after the 2a3s you'd be disappointed with both KT88s and ultralinear. I'm personally going with 2a3 and/or 845 because they're cheap in basic Sovtek or Chinese flavour, and I prefer a thinner more focussed sound than the usual 300b amp.
Depends what sonic flavour you like - big and warm or clean and precise. Also speakers, source equipment, room size, listening material etc - what are they?
Folks:
This sounds interesting -- I'm also considering building a new tube amp. My priority is sonics (cost is less of an issue) and a design that is suitable for a relative novice. I'm using an AES SuperAmp Signature right now and would like my next amp to be a qualitative step up. That said, I also need at least 15 watts (preferably 20). If you have an idea for a suitable project, I'd be inclined to join in.
Regards,
Scott
This sounds interesting -- I'm also considering building a new tube amp. My priority is sonics (cost is less of an issue) and a design that is suitable for a relative novice. I'm using an AES SuperAmp Signature right now and would like my next amp to be a qualitative step up. That said, I also need at least 15 watts (preferably 20). If you have an idea for a suitable project, I'd be inclined to join in.
Regards,
Scott
I'd go with PP 2A3 as well. Have considered Frank's PP 2A3 somewhere in this forum, but Ithink I would like to use an interstage this time to keep it simple and since I haven't done any IT coupled project yet, it is self serving.
I have considered both PP and PSE and based on what I've gathered in the past from various opinions as well, it seems PP is much more of a better option.
This forum had an EL34-inspired PP project with the design coming from the hard core folks in particular Wayne (cogsn.. something). How about this folks, a DIY Audio deigned PP 2A3??
I have considered both PP and PSE and based on what I've gathered in the past from various opinions as well, it seems PP is much more of a better option.
This forum had an EL34-inspired PP project with the design coming from the hard core folks in particular Wayne (cogsn.. something). How about this folks, a DIY Audio deigned PP 2A3??
I intend balanced all through, with diff pairs and CCSs underneath. Cap coupled with teflon caps.
The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now.
Andyjevans,
Could you tell me what CCS stands for and what's so good about it?
Thank you very much.
Kay
The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now.
Andyjevans,
Could you tell me what CCS stands for and what's so good about it?
Thank you very much.
Kay
I've been reading some user experiences of the Edcor interstages at www.edcorusa.com particularly the 10k-10k. Maybe this could go in the mix. No DC possible - parafeed sounds good apparently. Also could be an input transformer
Here's another idea using it:
http://db.audioasylum.com/cgi/m.mpl?forum=tubediy&n=63048&highlight=edcor+interstage&r=&session=
Here's another idea using it:
http://db.audioasylum.com/cgi/m.mpl?forum=tubediy&n=63048&highlight=edcor+interstage&r=&session=
The next amplifier I am going to build is the SETH PP2A3. It will use a center tapped choke as phase splitter.
Driver: 801a choke loaded. Reason: I just have to try a DHT as driver one day.
The basics : http://www.magnequest.com/diy_lessard_circuit_2a3pp.htm
Driver: 801a choke loaded. Reason: I just have to try a DHT as driver one day.
The basics : http://www.magnequest.com/diy_lessard_circuit_2a3pp.htm
The next amplifier I am going to build is the SETH PP2A3. It will use a center tapped choke as phase splitter. Driver: 801a choke loaded. Reason: I just have to try a DHT as driver one day.>>
I thought the 801 was a power tube? Are you thinking 3 stages here, if so, what's the first gain stage? Are you interested in some of the other DHTs like 01a, 12a, 26, 30, 31, 46, 71a etc? There's even some dual DHTs like 3a5 and 3b7.
I was thinking 26>46>2a3 or 12a>71a>2a3 or something like that. All the small signal DHTs are NOS - can't think of a new production one.
Are some of us near enough on this venture to pool ideas and design a 2a3 PP amp with various experimental input stages?
I thought the 801 was a power tube? Are you thinking 3 stages here, if so, what's the first gain stage? Are you interested in some of the other DHTs like 01a, 12a, 26, 30, 31, 46, 71a etc? There's even some dual DHTs like 3a5 and 3b7.
I was thinking 26>46>2a3 or 12a>71a>2a3 or something like that. All the small signal DHTs are NOS - can't think of a new production one.
Are some of us near enough on this venture to pool ideas and design a 2a3 PP amp with various experimental input stages?
PP2a3
I have a pair of pp 2a3 that went through quite an evolution. I had read on a couple of sites that an ideal pp amp was really two se's coupled together, so I tried just that - two se amps on same chassis, using a paraphase type of phase splitter (worked pretty well) and two 125ese ot with the outputs paralleled out of phase. It actually measured and sounded pretty good. The driver for each tube was a srpp 6sn7. Next was replacing the two 125ese with a single hammond 1615 pp transformer. This was an improvement in both the lower bass and treble areas, and I listened to the amps for about six months in this configuration. During this time, I had been reading Lynn Olsen's web site, and in particular his "Western Electric - A Rosetta Stone for Triodes" and began thinking about transformer coupled stages. I bought a lundahl 1676 input transformer to do phase splitting duties, so now I had transformer phase splitter, srpp driver. They were really sounding good! I used them this was for about a month. Next step was to add an interstage driver. I chose the lundahl 1660s. I am still using two 6sn7s as the driver, but they have been paralleled to lower the rp. I had considered and bought a pair of ecc99 for the driver, but I already had the n7's in place, and I like 6sn7's, so what the hell, I would give them a try. I had also read of others who felt the ecc99 was a little harsh sounding. At first, I was a little disappointed in this scheme - it sounded a little harsh, but I discovered I was making a mistake in my grounding. Each tube had its own cathode r and c, and these were tied to a 14g buss bar at whatever point seemed easist. The problem I had was the driver tubes cathode tie ins were straddleing the cathode tie point for the output stage on the buss bar - it was only a couple of inches. I adopted a star/central bus scheme where all grounds for the stage went to the same point, and the harshness immediately disappeared! After about a month I took the next step, which was to go to a differential arrangement in each stage (shared cathode resistor, no bypass). I also added WE style caps from CT of driver and out trans to their respective cathodes. I placed a small resistance in series with the caps (see discussion at K&K audio forum about the WE harmonic equalizer). Even though I have rather unfashionable electrolytics in the power supply (JJ), these amps sound very good, offering much more low level detail than I have heard from either my 300b se (Legacy clone, quite good) or Mac 60's. Those guys at Western Electric really knew what they were doing. One thing that became obvious during this whole process was that implementation becomes more critical as the circuit is simplified - you hear fewer passive colorations that mask flaws. Removing caps, especially between driver and output was a major revelation, and I had been using good caps before (musicaps and angela pio). Next step in the journey - I am setting aside funds for lundahl amorphous outputs, although I have been tempted to buy standard models a time or two. Good luck with you project!
Jim
I have a pair of pp 2a3 that went through quite an evolution. I had read on a couple of sites that an ideal pp amp was really two se's coupled together, so I tried just that - two se amps on same chassis, using a paraphase type of phase splitter (worked pretty well) and two 125ese ot with the outputs paralleled out of phase. It actually measured and sounded pretty good. The driver for each tube was a srpp 6sn7. Next was replacing the two 125ese with a single hammond 1615 pp transformer. This was an improvement in both the lower bass and treble areas, and I listened to the amps for about six months in this configuration. During this time, I had been reading Lynn Olsen's web site, and in particular his "Western Electric - A Rosetta Stone for Triodes" and began thinking about transformer coupled stages. I bought a lundahl 1676 input transformer to do phase splitting duties, so now I had transformer phase splitter, srpp driver. They were really sounding good! I used them this was for about a month. Next step was to add an interstage driver. I chose the lundahl 1660s. I am still using two 6sn7s as the driver, but they have been paralleled to lower the rp. I had considered and bought a pair of ecc99 for the driver, but I already had the n7's in place, and I like 6sn7's, so what the hell, I would give them a try. I had also read of others who felt the ecc99 was a little harsh sounding. At first, I was a little disappointed in this scheme - it sounded a little harsh, but I discovered I was making a mistake in my grounding. Each tube had its own cathode r and c, and these were tied to a 14g buss bar at whatever point seemed easist. The problem I had was the driver tubes cathode tie ins were straddleing the cathode tie point for the output stage on the buss bar - it was only a couple of inches. I adopted a star/central bus scheme where all grounds for the stage went to the same point, and the harshness immediately disappeared! After about a month I took the next step, which was to go to a differential arrangement in each stage (shared cathode resistor, no bypass). I also added WE style caps from CT of driver and out trans to their respective cathodes. I placed a small resistance in series with the caps (see discussion at K&K audio forum about the WE harmonic equalizer). Even though I have rather unfashionable electrolytics in the power supply (JJ), these amps sound very good, offering much more low level detail than I have heard from either my 300b se (Legacy clone, quite good) or Mac 60's. Those guys at Western Electric really knew what they were doing. One thing that became obvious during this whole process was that implementation becomes more critical as the circuit is simplified - you hear fewer passive colorations that mask flaws. Removing caps, especially between driver and output was a major revelation, and I had been using good caps before (musicaps and angela pio). Next step in the journey - I am setting aside funds for lundahl amorphous outputs, although I have been tempted to buy standard models a time or two. Good luck with you project!
Jim
Kay, ccs is constant current source (or sink), check out my last thread for a document I posted on ccs. Also check out tubelab.com for his
simple 45... I used his 10M45 based ccs in place of the plate resistor
on my 6sl7/2A3
Andy... good idea on a new thread for dyiAudio 2A3PP, go for it.
(right now I'm leaning toward a 2a3 based amp, but now 100% sure)
Bas... check out this attached pdf file
The input is based on a 2a3 PSE from audiodesignguide.com,
the output is based on the Seth 2A3PP you mentioned.
THIS IS JUST AN IDEA... DO YOU THINK IT WILL WORK????
simple 45... I used his 10M45 based ccs in place of the plate resistor
on my 6sl7/2A3
Andy... good idea on a new thread for dyiAudio 2A3PP, go for it.
(right now I'm leaning toward a 2a3 based amp, but now 100% sure)
Bas... check out this attached pdf file
The input is based on a 2a3 PSE from audiodesignguide.com,
the output is based on the Seth 2A3PP you mentioned.
THIS IS JUST AN IDEA... DO YOU THINK IT WILL WORK????
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