The 5963 is a 12AU7 with a reformulated cathode coating designed to withstand long periods of no current flow common in computer applications. All other specs should be the same as a 12AU7 and I have used them as 12AU7's in audio applications. The 12AT7 is quite different with considerably more gain than either the 12AU7 or the 5963.
CMC is Computer Measurements Company. They made frequency counters and other test and measurement equipment in the 1960's. They did not make tubes, but had major manufacturers brand their tubes for them. Your particular tube in an RCA.
The heater wire is inside the cathode rod. It's purpose is to get the cathode red hot so it can emit electrons into the surrounding vacuum.
Tube at low voltage makes a really nice distortion effect for guitar , very pleasing distortion
Thanks for the info, George. So, does that mean that the protruding red pillars are part of the Cathode?
In the previous circuit (a variation on Merlin's 'Valves at low voltages'), the other tubes (12AX7, 12AT7EH, 6H23P, 6DJ8) gave good sounds but not the 5963, it sounded really muffled and perhaps lacking dynamics. I can't compare with a 12AT7 since the one I ordered arrived as this RCA 5963...
New circuit yesterday, an inversion, gave good first results, without any tweaks. I will try some shielding to see if I can tame the low level hiss and what sounds like popcorn noise although I am not sure it is this. The hiss isn't audible when music is playing, only when I stop playback so it's not such a big deal in practice, but still, it would be great to minimise it, so that's another experiment.
One of the next tests is to try an SRPP configuration but I am short of paired tubes for stereo as all the recent scores and purchases are single tubes. I do have a pair of 12AX7 from a Behringer Tube Composer. I may test a one-channel tube SRPP but if I can replace one of the tubes by solid-state I'll rather have that in a final build. What works well here, the 10M45 on top?
The current build is a hybrid headphone amp. The prototyping setup is also used to explore circuits for my next build after that which is going to be first, a one-stage preamp, and then a two-stage one so that I can use a set of modules in between - much like my DIY analogue modular - for various applications (audiophile, guitar dist, phono, etc...).
I also have a set of modules for distortion reduction I need to assemble and test. This part should be a lot of fun if it works.
Interesting that you are working on a hybrid headphone amp. JPS64, Vunce, and myself have been working on a new hybrid using a Russian 6N6P tube. This is a verification build for purposes of testing set points and sound quality.
The glowing red rod IS the cathode. The heater wire is inside it to make it hot.
A 5963 is a 12AU7 which is quite a bit different from a 12AT7 or 12AX7. 12AU7's are commonly seen in some audio equipment and guitar amps, but it is not known for low distortion or noise. It could be made to work in your circuit, but some resistor value changes would be needed and the gain would be about 1/3 of what a 12AT7 could do.
I tested several hundred 5963's for a forum member last year who is actually going to use them in vacuum tube computer circuits. My tests measured the THD and plate voltage on each half of the tube in a simple amplifier stage. The plate voltage measurements told me if the tubes were suitable for computer use, but the THD numbers confirmed what I had heard on the internet for years.....12AU7's suck for low THD audio amps. Yes, I have tested some real 12AU7's in the same test fixture including some pricey Telefunken ECC82's and other boutique tubes years ago before selling them. The 12AU7's produce about 1% THD albeit it's mostly all second harmonic. Really good ones (rare) get below .5% but some are near 2%. The same fixture can do .2% to .5% with a 6DJ8 at the same output levels.
Did a re-test this morning. Happy to report that there was in fact nothing wrong with the 5963 even in the default configurations. It sounds good.
I probably miswired the heaters because I kept them in the configuration for the 6DJ8 and related tubes. These require a different wiring although we can keep 6V DC.
Also added a gate stopper to the output transistor to see if that tames the hiss in the previous circuit which sounds really good except for hiss and crackle, but that wasn't it. Haven't tested a proper shielding solution yet.
Accordingly, the 5963's box received a proper RCA label thanks to George.
Tests with my 12AT7EH at 6V for the heater doesn't show any glow that I can see.
I probably miswired the heaters because I kept them in the configuration for the 6DJ8 and related tubes. These require a different wiring although we can keep 6V DC.
Also added a gate stopper to the output transistor to see if that tames the hiss in the previous circuit which sounds really good except for hiss and crackle, but that wasn't it. Haven't tested a proper shielding solution yet.
Accordingly, the 5963's box received a proper RCA label thanks to George.
Tests with my 12AT7EH at 6V for the heater doesn't show any glow that I can see.
I added a couple SSR speaker protection boards to my DH-220C (C is for Cordell) this evening. They went in like a charm. I even was able to use the holes in the base from the long gone original power supply.
Fired up the first time with great silence, eliminating the big power on thumps, followed by excellent music amplification. The amp is still dead silent when the music stops. No background noise at all from the speakers.
There is still a bit of power off thump, but it is soft and not concerning.
First time firing up the soldering iron in a while. Felt good. 😎
Fired up the first time with great silence, eliminating the big power on thumps, followed by excellent music amplification. The amp is still dead silent when the music stops. No background noise at all from the speakers.
There is still a bit of power off thump, but it is soft and not concerning.
First time firing up the soldering iron in a while. Felt good. 😎
Attachments
Nice work, VonAh! You are using a SMPS otherwise I would suggest making the low capacitance PSU to shut down the SSR instantly upon power off.
it was a late night last night but I finally got the new Emerald Physics amp all buttoned up and the VU meters working. Still missing some parts for the slick XLR/RCA input jacks panel with auto-switching via relay.
VU meters in action here:
it was a late night last night but I finally got the new Emerald Physics amp all buttoned up and the VU meters working. Still missing some parts for the slick XLR/RCA input jacks panel with auto-switching via relay.
VU meters in action here:
Thanks, you two.
I have the extra little boards for the SSR PSU, but haven’t ordered the parts. If the thump ever bothers me, I’ll fill the boards. It’s been playing all day with my Audax Karlsonators and I really like the combination.
The new proto amp looks great, X. A lot of good stuff in one box! You’ll have to fill us in on its comparable sound qualities…
I have the extra little boards for the SSR PSU, but haven’t ordered the parts. If the thump ever bothers me, I’ll fill the boards. It’s been playing all day with my Audax Karlsonators and I really like the combination.
The new proto amp looks great, X. A lot of good stuff in one box! You’ll have to fill us in on its comparable sound qualities…
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One thing this amp does really well is bass slam. The dynamics of an IcePower 1200AS2 is incredible. I like the overall presentation. Very listenable and fatigue free. The tube buffer makes it sound wonderful.
New caps came for my old MOSFET. Going with 2 6800 low ESR rather than the 2 22, 000. Original was only 6000. Yes, it has a bigger bridge.
Yes, burning Teflon releases Hydrogen Cyanide.
Yes, burning Teflon releases Hydrogen Cyanide.
A member of SBAF (Yotacowboy) came by my lab to pick up the Vanguards for an audition/review. He also got a tour of the lab. We listened to this playlist for a bit.
https://music.amazon.com/user-playl...e7d0bsune?ref=dm_sh_L4DG1TUpshcVkn2x79xnsJKPu
https://music.amazon.com/user-playl...e7d0bsune?ref=dm_sh_L4DG1TUpshcVkn2x79xnsJKPu
On the bench is the BTSB “Lite” basically a balanced XLR/TRS or SE RCA auto switching rear panel for an amp. It’s passive in that all it does is use a relay to automatically switch the negative phase of a balanced connection to ground when using single ended RCA input. It uses an isolated DCDC converter to keep the 12v input PSU ground separate from ground that activates the relays. Jhofland designed this for the rear panel of the EP600 amplifier. It provides a clean interface so that connectorizd wire assemblies can be used without having to use any flying leads. It provides two balanced signal wires to the balanced inputs of the HyperSET balanced hybrid tube buffer for the amp.
Nifty device. Hope you had a great Christmas.
All fairly quite here, we had a good time. I wasn't prepared to offer her the completed headphone amp, but gave her the parts that will make it up in the end. Still have some research to do. Yesterday, I played with some sims in the morning. Also had the breadboarded prototype play a few songs for her. She liked the sound.
Thinking of allowing a switch to enable swapping of tubes like 12AU7 to 6DJ8 in the final build. Not difficult, but I suppose she won't even roll tubes. If she does roll tubes, then I'd have to do the re-biasing for her too. It's not a problem per se, but it would probably be better to have a more automatic way of biasing rather than put a screwdriver to the trimmers and using a voltmeter.
This reminds me I wanted to check your hybrid tube headphone amp thread if there's one.
All fairly quite here, we had a good time. I wasn't prepared to offer her the completed headphone amp, but gave her the parts that will make it up in the end. Still have some research to do. Yesterday, I played with some sims in the morning. Also had the breadboarded prototype play a few songs for her. She liked the sound.
Thinking of allowing a switch to enable swapping of tubes like 12AU7 to 6DJ8 in the final build. Not difficult, but I suppose she won't even roll tubes. If she does roll tubes, then I'd have to do the re-biasing for her too. It's not a problem per se, but it would probably be better to have a more automatic way of biasing rather than put a screwdriver to the trimmers and using a voltmeter.
This reminds me I wanted to check your hybrid tube headphone amp thread if there's one.
I don’t have a hybrid tube headphone amp thread. Just a commercial product called the HyperDrive-2 and related preamp called HyperSET. Both use same E88CC tube buffer and solid state balanced drivers. The HyperDrive uses the state of the art headphone amp Class AB chip amp TPA6120A2 for 2W of power into 32ohms.
I also have a new tube hybrid SS SE Class A amp under under development using 6N6P and IRF610 MOSFET with solid state CCS.
I also have a new tube hybrid SS SE Class A amp under under development using 6N6P and IRF610 MOSFET with solid state CCS.
Hi X , Have you tried FQP3N30 mosfet? I am using them right now in my DCA ? They seems to have better treble than IRF610
No worries, plenty of cool things to look at. Been thinking a lot about the set of small drivers I salvaged from a Sony boombox, so that very clean looking crossover might be interesting as I want to multi-amp it all.
Very cool indeed. I tested 510 and 610 in my little breadboard, and 610 is better to me.