A heater-lift circuit will work to help that issue, but I wouldn't fuss too much if you can easily use DC- at least on the preamp/splitter portion of the amplifier. If you have 12SN7 types this would be an excellent application for them, as a 12 volt regulator would be a swell solution when used with a simple diode bridge, cap, and a suitably sized heatsink.
Then I wont either..they take up way too much space anyhow
Do you like the amp with the Concertina Splitter better? I was going to build the original first then experiment later.
I was thining of integrating a stack of VR tubes (2 VR150 per channel) if I can fit them in as I am a sucker for the glow
Last edited:
I haven't tried the differential yet, but in general I really like the concertina splitter setup, and use it almost exclusively on small voltage swing applications like this. I've been meaning to try out a version with the alternative splitter for a while. The measurements sure do look lovely, so I plan to try it soon.
I wish I had the chassis space, it would be cool to try 5842 into transformer phase splitter.
My goal with this build is to put the same effort into it that I would but into a DHT headphone amp and see if it sounds better. I have two other builds I am working on at the same time, so I can compare this to the 71a and 47 headphone amps.
My goal with this build is to put the same effort into it that I would but into a DHT headphone amp and see if it sounds better. I have two other builds I am working on at the same time, so I can compare this to the 71a and 47 headphone amps.
Last edited:
usually headphone are rated at 1mW.
so at 1W, it will be around 123dB.
that's pretty inefficient when it comes to headphones, they are usually in the 100dB/1mW range. But at 93dB/mW, it is still ear shattering at 1W.
Here is recommended power for typical high sensitivity dynamic headphones:
810mW into 16Ω
940mW into 32Ω
270mW into 150Ω
135mW into 300Ω
68mW into 600Ω
Similarly, low sensitivity planar dynamic headphones need like 3W maximum, and the voltage is almost the same for them independently from their impedance.
Here is my version of a headphone amp: left TRS is for high sensitivity headphones, XLR and right TRS are for low sensitivity headphones. The amp can deliver 6W for <1% THD on 32 Ohm load, to have a headroom.
810mW into 16Ω
940mW into 32Ω
270mW into 150Ω
135mW into 300Ω
68mW into 600Ω
Similarly, low sensitivity planar dynamic headphones need like 3W maximum, and the voltage is almost the same for them independently from their impedance.
Here is my version of a headphone amp: left TRS is for high sensitivity headphones, XLR and right TRS are for low sensitivity headphones. The amp can deliver 6W for <1% THD on 32 Ohm load, to have a headroom.
Attachments
Got all the holes cut and started stripping the old paint from the transformer endbells. The choke I am using is from an old HP freq generator and is covered in varnish, which makes is a royal pain to strip because I have to remove the varnish to get down to the paint. I should have everything powder coated tonight or tomorrow and start wiring this weekend.
I decided on a vintage Triad 700vct power transformer and going to use LC filtering, with 5AR4 rectifier. I would add another LC stage, but would be under 300V, its going to be close as it is. PSUDII has me at around 298V B+
I decided on a vintage Triad 700vct power transformer and going to use LC filtering, with 5AR4 rectifier. I would add another LC stage, but would be under 300V, its going to be close as it is. PSUDII has me at around 298V B+
Last edited:
I think I am going to try and use VR tubes. Instead of LC, will go with CLC into a stack of 0a2 VR tubes per channel, CCS on each stack. Hopefully, I have room. I am using a 3" tall chassis which is great for mounting things on the sides. This is a headphone only amp so I dont have to worry about speaker jacks. The 0A2 tubes are very small, so hopefully I can fit four of them on the chassis. The biggest challenge is going to be the space needed for the headsink.
Not yet.
I saw headphone amplifiers with 6S33S output tubes.
You wouldnt happen to have a schematic for one would you?
OK, so I tried this with my son's pair of Audio Technica ATH-m50x headphones and the amp drove them perfectly, good clean sound with volume around 10 oclock. Now with the Hifiman HE4xx, volume needs to be around three oclock for OK volume, but I feel like I still need more power for them I think I need around three watts for these power hungry cans!
I think I need around three watts for these power hungry cans!
Member
Joined 2009
Paid Member
Thanks
Powder coating the end bells was a pain because I had to strip all the old paint off them and the "Illusion Cherry" powder coat was two steps, but I am happy with how they came out. I coated the chassis "Speedway Gray," which was only one coat, so not as bad. I will pop the bottom plate off and snap a couple of pics if I get a chance (or actually pry myself off away from listening).
I was thinking of biasing the 6SL7 with LED (for more gain for the planars), good or bad idea?
Well, after some more listening, this amp just doesn't have the oomph to drive planars I don't want to build another amp just to power one set of cans, but I think I'm going to have to resort to SS to drive these This amp doesn't seem to have enough current drive for planars 
I have tried the amp with dynamic cans and the sound is amazing with plenty of bass. Any high current, low power tubes? Maybe 12b4a?
I don't want to build another amp just to power one set of cans, but I think I'm going to have to resort to SS to drive these This amp doesn't seem to have enough current drive for planars I have tried the amp with dynamic cans and the sound is amazing with plenty of bass. Any high current, low power tubes? Maybe 12b4a?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.