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Favorite EL-84 amplifier?

albusark said:
Do you think there's a significant improvement in sound between the SCA-35 and ST-35? Transformers and output tubes are the same. Am I wrong in thinking that they must sound very similar?
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Yes, the performance is the same. Excellent. There is however easier to have hum under control in ST-35.
 
Gigantic said:
I'm very fond of my modded Glow Audio Amp Twos that I'm using as differential mono blocks. View attachment 3564007
View attachment 3564008View attachment 3564009

They're handsome little buggers, not vintage, but are based on a classic circuit:
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When I got them, I thought they'd be a stopgap until I could afford something "good," however after rolling tubes and replacing capacitors with better grade electrolytics and films, I've stopped longing for anything else. I may upgrade the iron at some point, but I expect improvements to be somewhat marginal. Designed by Kara Chafee of DeHavilland EAC, but manufactured in Hong Kong for a US company, the amps are of significantly better quality than many, if not most Chi-Fi amps at their price point.
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I'm with you on upgraded Chifi. I got my Chifi OTL headphone amp over a decade ago, a little bear p8 in the metal chassis build toroidal transformer. I replaced all of the capacitors and added a thermistor to cool it off, it sings like an angel. Your amps look fantastic spec wise and I'm sure they're just about all you'll ever need as long as you get goosebumps every now and then listening to them.
 
gadget73 said:
I'm guessing that Decware unit is push-pull since you say its got two EL84 per mono amp? Or is that one of their single ended stereo amps wired in mono mode, so its parallel single ended? Not sure which specific circuit you're working with but all of the Decware schematics I've found were either zero feedback triode-wired or plate to plate feedback setups with relatively low feedback levels. I wouldn't think that should make for an "analytical" sound, SE amps, especially ones with low or zero feedback tend to have very strong amounts of tube flavor.
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It's a single ended circuit. It is the Decware Zen Triode circuit simplified with solid state rectification and no optional switches, otherwise a Zen Triode amp. https://www.decware.com/newsite/SE84CDIY.htm I was asked to build the monoblocks as the waitlist for Decware amps is over 3 years at this point.
 

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opnly bafld said:
Decware kit is either parallel or series (recommended by Deware) single ended triode.


@albusark

Have you ever heard a stereo SE84UFO with tube rectification?

2 single ended I like, unfortunately rare and hard to get, Vaughn Carina (T or UL) and Grommes PHI-26 (T or P).
The Almarro A205A (P) is also pretty good, but like above not for sale often.
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I'd love to hear the tube rectification to compare. I imagine it adds a great deal of character. I like solid state rectification on certain amps, like the ST-70 series II. But I think this solid state power supply on the Zen SET circuit maybe makes it sound a bit ... solid state.
 
ARC Tech-109 said:
Heathkit AA-111 that I've had since 6th grade.
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I'm finishing a rebuild of a Heathkit signal tracer right now and there's so much to admire with their design choices. This amp looks like my cup of tea, classic design and simple deliberate circuit design. I will add it to my bucket list. I'd love to hear one.
 
blademan13 said:
I have only heard a few EL84 based amps. Favorite is a recently acquired new build Dynaco ST-35 consisting of Dynakit Parts stainless chassis and transformers, Dave Gillespie circuit boards and EFB board and NOS PIO Russian surplus caps. Running NOS Bugle Boys on outputs. Sound blows me away, simply rich and holographic. I have amps I prefer overall, throw on Skynyrd’s Second Helping or some Marshall Tucker at low volumes and this amp simply shines.
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You have an S-Tier end game amp. Gillespie mods and bugle boys damn.
 
albusark said:
Wow that amp has a lot of discussion attached to its name. How does it sound to you?
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Really lives up to its fine reputation, actually a notch higher, with responsibly and thoughtful rolling of tubes and caps it is possible to "tailor" to the taste of your own ears, listens mostly to SET 300B and 2A3 amplifiers, but this little jewel does not need to be ashamed of itself and does not hold back with the right speakers!
 
Single biggest difference between the SCA-35 and ST-35 is the tone controls go away. The amp itself is also somewhat different, same basic topology but all triodes instead of a triode-pentode if that kind of thing bothers you. Less open loop gain because it loses the tone controls. The stock SCA35 power amp section is extremely sensitive to allow for the lossy passive tone control circuit.

Personal opinion, but I think the line stage / tone control stuff in a lot of old integrated amps degrade the performance of an otherwise capable power amp section. The ASR-433 is a real fine example of that. The tone controls aren't awful but there is a whole lot of extra switching up front that does nothing useful for the sound. I got a lot of improvement from mine by bypassing all of that, along with the second set of volume controls. The phono stage is also not very good. Mine now has a Harman-Kardon A500 stage. That wanted DC heat in order to be completely quiet too. Overall the engineering on the 433 is better than average, the grounding setup is a proper buss design and all of the wiring from the input jacks to the front and back to the circuitry is shielded. Most mfg were not doing this. They are very quiet amplifiers.

so with all that said I might aim more for power amps only so you can run whatever you want in front of them and not be limited by whatever the designers 60 years ago did because of budget and marketing constraints.
 
albusark said:
I'm with you on upgraded Chifi. I got my Chifi OTL headphone amp over a decade ago, a little bear p8 in the metal chassis build toroidal transformer. I replaced all of the capacitors and added a thermistor to cool it off, it sings like an angel. Your amps look fantastic spec wise and I'm sure they're just about all you'll ever need as long as you get goosebumps every now and then listening to them.
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I’d hesitate to call it chi-fi: it’s an American company, American design and presumably a modicum of American quality control (I do have some understanding of how Sino-American manufacturing operates) and manufacturing in Hong Kong, which is a bit different than Chi-Fi operations in nearby Shenzhen, where a good deal of Chinese valve amps are made.
 
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