I'm thinking about building an Allen Wright PP2C amp (PP KT88 tubes).
Apparently max output is in the 25 watt range.
I have fairly efficient speakers and a small room, so will probably NEVER have the amp more than 'half open'.
Question: will using an output transformer rated for greater wattage improve (or detract from) the 'sound' - e.g. better bass response or other benefit.
Comparing two OTs with similar specs, one rated at 30 watts, the other at 50 watts, is there any point in going for the greater weight (and shipping expense) of the larger OT?
For example:
Edcor CXPP30-5k
EDCOR - CXPP30-5K
vs
Edcor CXPP50-5k
EDCOR - CXPP50-5K
In this case the 30 watt version has multiple output taps, but please ignore this difference.
I know that in guitar amps the OTs are sometimes deliberately undersized; this is a question from the other end of the amp continuum.
Thanks!
Apparently max output is in the 25 watt range.
I have fairly efficient speakers and a small room, so will probably NEVER have the amp more than 'half open'.
Question: will using an output transformer rated for greater wattage improve (or detract from) the 'sound' - e.g. better bass response or other benefit.
Comparing two OTs with similar specs, one rated at 30 watts, the other at 50 watts, is there any point in going for the greater weight (and shipping expense) of the larger OT?
For example:
Edcor CXPP30-5k
EDCOR - CXPP30-5K
vs
Edcor CXPP50-5k
EDCOR - CXPP50-5K
In this case the 30 watt version has multiple output taps, but please ignore this difference.
I know that in guitar amps the OTs are sometimes deliberately undersized; this is a question from the other end of the amp continuum.
Thanks!
Well, each OT is a compromise between simply said the capacitance and inductance. The more inductance and larger core will give better bass response, but this comes also with more capacitance between the winding's, so worse high response.
Again, this is basic and simply said.
There is no ideal OT and it's a difficult task designing and making one.
Again, this is basic and simply said.
There is no ideal OT and it's a difficult task designing and making one.
This decision should somewhat depend on both your music and listening tastes. Several here claim that an oversized OT will provide greater headroom, which it will. If you cherish humongous crescendos in classical music or screaming pounding rock music, then the larger transformer would be advantageous. But if you're into subtle and more detailed music like human voices or small instrumental groups, then I think the smaller OT would be better. I read a book years ago by the late Harvey Rosenberg who listened to many amplifiers with both large and small OTs. He was certain that smaller transformers always sounded better. And I tend to agree. Of course sound will also depend on the quality of manufacture.
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Why not ditch your Push Pull plans and go single ended? Perfect for your smaller room and seems your speakers could cope. Plenty of 300b designs out there, and a lot of them are simple 2-stage solutions with a high-mu input tube.
In this case, you just need a good 3K or 5K SE OPT. If you want the ultimate, go with Monolith Summit. Otherwise you'll get really good sound with a Lundahl LL1664 or LL1663. Monolith is very big, Lundahl is quite small. But both really excellent. Either way, it's design and materials.
In this case, you just need a good 3K or 5K SE OPT. If you want the ultimate, go with Monolith Summit. Otherwise you'll get really good sound with a Lundahl LL1664 or LL1663. Monolith is very big, Lundahl is quite small. But both really excellent. Either way, it's design and materials.
If you look at the spec (click on the "specification" tab on web page), one is 30W/5K, and another is 50W/6.6K. They are not equal in terms of primary impedance.
I would suggest to choose 2nd because it has higher primary inductance, and thus, you may get lower distortions at low frequencies.
Max power output will be higher with 1st, but I don't think its an issue in your particular case.
I would suggest to choose 2nd because it has higher primary inductance, and thus, you may get lower distortions at low frequencies.
Max power output will be higher with 1st, but I don't think its an issue in your particular case.
+1 On Single Ended two stages amp but not expensive tubes as 300B or 211, in case you use 300B or 211(etc) tubes you would be in the hands of Chinese tube manufacturers.
My suggestion is go Triode SE with EL34/SV83/KT88 for 7W or KT150(yet a affordable tube) for conservative 15/20W; but if you want go BIG and live in a cold area you can sports the GM70 a really inexpensive Triode tube w/all the military Russian quality.
Good luck
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Thanks for pointing that out..
The Edcor website has some errors- the specs for the 6.6k transformer are listed in the 5k page by mistake. One of the 50watt transformers has a link indicating 30 watts...there may be more.
I was comparing OTs with the same primary impedance but different power ratings, and they had the same 'frequency response' and THD numbers listed.
That idea - 300B, Lundahl iron, etc. is in the 'way too expensive' category for me.
It will be 'a frosty day in hell' when I spend $2000 CAD on parts for an amp
. This is just a hobby for me, and besides that I have 70 year-old ears, so they are not worth the expense!Thanks for the suggestion, though.
That idea - 300B, Lundahl iron, etc. is in the 'way too expensive' category for me.
It will be 'a frosty day in hell' when I spend $2000 CAD on parts for an amp
Thanks for the suggestion, though.
OK - the cheap solution. This is a more complex build but with cheaper parts. Parallel 4P1L in triode as output tubes. These are $5 DHTs, incredibly good sounding - up there with 300b, 2a3 and the rest of them. Think of them as a 45 equivalent but with a gain of 11. A couple are the same as a 2a3, and 3 in parallel will give you 1.5 times a 2a3. Do the output in push pull even for more power. They run on 250v plate to cathode, so no high voltages. I have 150 of them so I laugh at expensive output tubes. I use them in filament bias, which is the complex part. Long threads on this forum. Look all this up on Ale Moglia's website, Bartola Valves - and use an 01A or 26 as input tubes. I can't think of a better sound, and I've built loads of 300b and 2a3 amps.
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Thanks for that suggestion. Certainly those tubes are more in my budget range. I have a strong resistance to 'boutique' parts and I can accept the fact that I may be missing 'the ultimate sound' as a result.
I have a pretty good-sounding EL34 SE amp right now:
Details here:
http://www.diyaudio.com/forums/tubes-valves/182989-building-something-better-chinese-se-el34b-amp-diy-kit.html
I thought I'd try a PP amp with more power. I do like listening to bass ('The Beat Goes On' from a Patricia Barber recording is on my 'test' CD), and I'm curious whether an amp with a bit more power to spare makes any difference.
I've had some of the parts for the AllenWright PP2C amp on the shelf for a while and I'm thinking it should go to the top of my list for 2017.
Thanks Andy. I see a lot of happy reading in the next few days, based on those ideas you've just mentioned.
It seems to me that SE amps generally need better/more expensive OTs to perform well (compared to PP) . Is this your opinion as well?
Also, the SE OTs in my parts collection are mostly from cheap console stereos, but finding decent quality PP OTs seems easier (Bogen, Fisher, Heathkit, etc).
I do have a couple of pairs of good SE OTs somewhere waiting for the right project.
And, Edcor iron is very reasonably priced. You might think that (Canadian made) Hammond iron would be very reasonably priced here in Canada but it's not the case, unfortunately.
Definitely true. I have purchased Edcor transformers and even with the very expensive priority mail shipment from
New Mexico to Toronto, Canada I have found their prices to be far more competitive than equivalent Hammond
products manufactured in Canada. I think Edcor transformers are very good value for money.
Well, some of us on this forum only use DHTs. I've used nothing else for around 7 years. I'm addicted to the transparency and vitality you get with them. 4P1L, 26 and 01A are still cheap and available so I've stocked up on those. I can get away with 2 stages in total, including line stage, given that 4P1Ls have a gain of 11 in the output stage. But 3 stages gives you flexibility and a bit more heft.
I've long planned to make a 4P1L PP amp - using twin 4P1Ls, so 8 in the output stage altogether. I'd drive it with another 4P1L into an interstage phase splitter. Then use the Bartola 01A Gen2 preamp, which is superbly good. You need Rod Coleman filament regs for all this - his site is Lyrima. I use filament bias right through, so I don't need to use any cathode bypass caps, but you don't need to.
VictoriaGuy,
The PP2C is a great design, so if you have the parts for it then build it. It will be clean and clear, Allen Wright's signature, with enough power to make speaker selection a non-issue.
I built one and then later on changed the output stage to DHT 6B4G. I think the dht version sounds better but it was an incremental improvement, not night-and-day.
I also have an SE amp, a version of Tomas 'VinylSavor' Mayer's 6cb5a design, which uses Lundahl interstage transformers and James outputs. My speakers are 90 db efficient and an easy load. Below 70hz is handled by a subwoofer. Back to back There is no obvious push-pull or se sound. They both sound good, the pp2c may be a touch more dynamic. Build it and be happy.
Dht' s on the output with Rod C regs would be a very nice thing but it's a whole extra level of complexity.
Btw I'm a "Victoria Guy" too. Victoria, Australia that is! We're practically neighbours, you must pop in some time
The PP2C is a great design, so if you have the parts for it then build it. It will be clean and clear, Allen Wright's signature, with enough power to make speaker selection a non-issue.
I built one and then later on changed the output stage to DHT 6B4G. I think the dht version sounds better but it was an incremental improvement, not night-and-day.
I also have an SE amp, a version of Tomas 'VinylSavor' Mayer's 6cb5a design, which uses Lundahl interstage transformers and James outputs. My speakers are 90 db efficient and an easy load. Below 70hz is handled by a subwoofer. Back to back There is no obvious push-pull or se sound. They both sound good, the pp2c may be a touch more dynamic. Build it and be happy.
Dht' s on the output with Rod C regs would be a very nice thing but it's a whole extra level of complexity.
Btw I'm a "Victoria Guy" too. Victoria, Australia that is! We're practically neighbours, you must pop in some time
Rhone-
Thanks for the info.
What OTs did you use for your PP2C build?
I'm still trying to figure out what power rating (weight) of OTs to get...some say the bigger the better, others that the 'bare minimum' will give better sound.
It would have been nice if the Brits had more imagination when naming colonies...the Victoria thing.
Never mind...I had a very interesting chat online with a 'fellow kayaker' from WA..it took a day or so to realize he wasn't in the nearby US state...
Cheers
If you build the PP2C, you might also consider the K&K Audio designs that Kevin Carter has used with a CCS in the output stage common cathode making it a differential stage. I've done this on several amps and think it makes for a wonderful sound. It's super clear and detailed, similar to how SE seems to me in the mids and treble with a nice clean and tight bass. Take a look here at his blog and scroll to the PP amp. He provides a schematic and sells a nice higher current CCS kit.
K&K Audio | Blog
By the way, I'm following some of Andy's advice and building a Bartola 01a line stage. I have the Coleman regulators and the Bartola gyrator kits on hand. Waiting for some other parts to get started. Also thinking of a new PP amp using the 4P1L's for the driver stage.
Happy New Year and happy building,
John
K&K Audio | Blog
By the way, I'm following some of Andy's advice and building a Bartola 01a line stage. I have the Coleman regulators and the Bartola gyrator kits on hand. Waiting for some other parts to get started. Also thinking of a new PP amp using the 4P1L's for the driver stage.
Happy New Year and happy building,
John
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From my experience, PP using el84 or similar is a nice way to get solid power (for a small space) without breaking the bank. Indirectly heated triodes usually don't need DC power supplies either. NO need to go for exotic blablabla if you don't need it.
A good friend of mine over 65 suggested that tweeters and whizzers were "a waste of money" for him. To be honest, I'm not yet 50 and I tend to agree with him.
Here's the ultimate cheep solution - get a nice old el84 PP and modify it. Search around for something like a eico HF-81 or HF86 that works but doesn't look pretty and make a project out of it. Maybe two defective units will yield one running one. Be prepared to pay flea market prices.
Ian
A good friend of mine over 65 suggested that tweeters and whizzers were "a waste of money" for him. To be honest, I'm not yet 50 and I tend to agree with him.
Here's the ultimate cheep solution - get a nice old el84 PP and modify it. Search around for something like a eico HF-81 or HF86 that works but doesn't look pretty and make a project out of it. Maybe two defective units will yield one running one. Be prepared to pay flea market prices.
Ian
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I'm using Lundahl 1664 outputs. They have a very limited range of connection options compared to other Lundahls and are quite low power so they are relatively inexpensive. Especially in Australia where postage adds a significant cost to any transformer - even Edcors are not cheap.Rhone-
Thanks for the info.
What OTs did you use for your PP2C build?
I'm still trying to figure out what power rating (weight) of OTs to get...some say the bigger the better, others that the 'bare minimum' will give better sound.
It would have been nice if the Brits had more imagination when naming colonies...the Victoria thing.
Never mind...I had a very interesting chat online with a 'fellow kayaker' from WA..it took a day or so to realize he wasn't in the nearby US state...
Cheers
Yes, indeed, CCS on the outputs featured on the ultimate development of Allen's PP design, the DPA300B.
Thanks for the pointer to the K&K blog. It's something to consider for my amp.
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