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I'm in need of expert help here.
The schematics of my SE EL34 tube amp (without negative feedback) is attached.
It has 1x 5Y3 Tube Rectifier, 2x 6N3 Driver Tubes and 2x EL34 Power Output tubes.
It can work with a Tung Sol 5Y3GT (currently) or Bendix 6106 (tried without problems).
I'm coming down with a bout of tube rolling "itch". ;)
In place of the 5Y3 rectifier, can I safely sub a 5U4G, 5R4GY, GZ32 or GZ34 rectifier into this amp?
Follow Ups:
Or more "tubey" organic tone? This may all be a PS design issue, rather than simply a rectifier issue.
Just a thought.
Ermm, I'm not exactly sure what I want, maybe that's the problem?? LOLOn my current amp and having rebiased each time to the manufacturer's recommended specs,
the Bendix 6106 (> 200 hrs use) has tight and punchy bass but the midrange is too stiff.
hence the change to
the Tung Sol 5Y3GT (> 200 hrs use) has warmer mids and great imaging and great natural tonality but the bass is really lacking. I could live with this forever but I keep missing the kick ass bass.
hence the change to
the Tung Sol 5U4G (> 30 hrs use) gave me back the bass with slightly warm mids. Mids are warmer than the Bendix 6106 but less than the Tung Sol 5y3GT. However, the imaging seems to have suffered and is less precise. Maybe I should burn in and use some more???
I'm still looking for that "perfect" rectifier.
Any ideas/suggestions?
I have the following rectifiers coming in though for tube rolling
1. RCA Jan 5r4GY
2. Philips 5R4GYS
3. Mullard GZ32I'm just not willing to spend the extra $$$ for one of those overpriced metal based GZ34s.... or maybe that is what can fix my sonic obsession?
will welcome any comments/criticisms or sagely tube rolling advice. :)
Edits: 09/30/12
I've sued several Bendix 6106's. And these rectifiers usually take a LONG time to break-in. They eventually sound pretty good in single-ended apps (like yours). I mean, many 1950's made 5Y3GT last like 25 years. So, the Bendix Red Bank tubes could last long enough to be past onto your next of kin. Really, I play my Vibro-Champ or Champ at "10" for a solid week or two (3-4 hours per day), to get the 6106 to "relax."
MY opinion, it's sound like you want neutral bass, but warm organic midrange. Really a good 1950's black plate GE, RCA, or Sylvania 5Y3GT may fit the bill.
The GE 6087 is gonna make the unit sound a lot like the Bendix 6106, in my experience. Both the 6106 and the 6087 were NOT made for home audio use. But, were originally designed to meet military specs. Knowing those sepec may help you figure out how they are going to sound in your unit.
The 5U4G will supply more potential current to the tubes. This may help the transients. Now, how this effects the imaging is prolly circuit design/tube design dependent.
Why not look for good NOS 1950's black plate 5Y3GT?
There is one other issue. The design of your PS filter section. Do you have a schematic of it? And what components are in the PS rail (what caps, chokes, & resistors). A well-designed PS can sometimes help keep the specific restifier's idiosyncracies out of the final product.
Hi FenderLover,
Yes, you have a valid point about the 5Y3 family of tubes being what I'm looking for. My Tung Sol 5Y3GT was made in the 1950s and comes with "D" getters and black plates.
I'll grab a couple of 5Y3s from various manufacturers and experiment along those lines.
As for the PS schematic, unfortunately the only schematic I have is what I've posted when I started this thread.
I've read many great reviews of 5R4 rectifiers but the max 4uf capacitor issue is the one thing which is keeping me from trying it out in my amp.
It's a constant point of argument amongst guitar amp (esp hi-end boutique) owners. "Gotta look at the BIG picture & not concentrate solely on rolling tubes).The Power Supply plays a very imporantant role in the dynamics of your unit. Bigger, IMHO, than using a specific "magic" tube rectifier.
Yes, the "right" valve may "tune" the output to your desired wants. But, you may find it a fleeting thing, as the tube breaks-in, the tone starts to go back to the undersirable start point. Whereas good PS design & construction may allow you to use a number of rectifiers --- and get similar pleasant responses.
I guess what I'm trying to say is, tube rolling SOMETIMES is an indication of weakness elsewhere in the overall design. Just taking a WAG, kinda ho-hum bass wqith good mids (with the OEM 5Y3GT) may indicate that the PS caps are not doing what they should be doing --- at least not when you push your unit (transients, playing loud, past 2:00 on the control).
You have a photo of your unit? Esp an "under-the-hood" shot? Be nice to see what kinda caps, resistors, and chokes are being used.
I hate to see a new entry to audio go down that "Now, I have 100 tubes and none of them seem to really give me what I totally want out of my system."
Have a good one! Hope your team wins, if you follow football or baseball (or both)!
Edits: 09/30/12 09/30/12
Here's what it looks like under the hood.
I believe that Clarity Caps were used.The review by 6 Moons was for the mk3 version.
Mine is the updated Mk4 version.
However, the internals should still be the same.In the meantime, I've decided to roll some Mullard GZ32/5V4G rectifers and see if my needs can be met, i.e. warm mids but with punchy and tight bass.
BTW, I'm using 2x NOS EL34 xf2 Mullards and 2x WE NOS 396a "D" getters.
Edits: 09/30/12 09/30/12
What are the rated mfd of those large diameter electrolytic caps (the ones rated at 450VDC)?
Agradece. E deixe o Bluebird de felicidade vir em seua vida!
Hi,
I believe that it is 22uf.
I must thank you for your persistent prompting! :)
After you asked me for a photo of the innards, I realised that the 2 big 450v caps were for the rectifier. It is in the correct position.
I then looked at the schematics again, on the top left corner, the cap for the rectifier is 22uf / 450v. On the right side of the diagram, there is also a 22 uf cap. The "/450v" must have been truncated due to a lack of space.
Why not try a GE 6087?
Controlled warm-up faster than the 6106.
Keeps voltage where schem dictates.
jstrm
Plug & Play- 5R4. About same voltage drop as 5Y3 due to not using near max rated current. GZ34 & 5V4G will raise high voltage to tube plates. You may need to set EL34 bias higher. The 6N3 have cathode bias thus will self adjust to a higher bias with higher voltage.
Another rectifier is a type 80 with four pin to octal base adapter. I like RCA 5Y3GT rectifiers. So did Jeff Korneff who is a premier SE amp builder.
Hi Neff,
Yes, I'm really tempted to try the 5R4 rectifier.
I have a couple of RCA-JAN "D" Getter 5R4GYs on hand.
After I evaluate the Tung Sol 5U4G, I'll attempt to sub in the RCA 5R4GY.
My only concern is that the 5R4GY datasheet specifies a max capacitor limit of 4uF.
I have gone to 50 when I was just starting out on this hobby, though I have become more and more conservative. IN a cap input supply, I go 1-2 UF then 10 henry choke, then 680UF bypassed with 470 picofarad silver mica, then another 5 or 10 henry, then a 10 microfarad polycarbonate. This approach being for a 6005 triode wired push/pull amp.
The Mind has No Firewall~ U.S. Army War College.
Thanks Cleantimestream for your advice.
I Googled some more about the 5R4 and the 4uf cap limit.
Some other audiophiles have also reportedly managed to use the 5R4 with a cap of up to 22uf in other amps without any problems whatsoever.
Thanks also to FenderLover's persistent line of questioning above which made me realise that the cap for the rectifier in my amp was 22uf.
So I went ahead and plugged in the JAN RCA 5R4GY rectifier into my amp.
It started up fine without any arcing - > which AFAIK is always a good sign with tube recifiers.
I shall let it burn in for 24 hours before I do any serious listening and comparison.
I'm keeping my fingers crossed, hopefully this has the tonal attributes of the Tung Sol 5Y3GT which I really like PLUS the bass which I can't do without.
Cheers! :)
~!
The Mind has No Firewall~ U.S. Army War College.
5U4 draws 50% more heater current than the others, so don't try it unless you're sure the transformer can take it. Add 5V4 to your list - same as GZ32, really. Expect to rebias since different tubes will affect B+, have different voltage drop.
I replaced the 5Y3GT Tung Sol with another Tung Sol 5U4G (Coke Bottle).
Nothing's blown up yet! :)
I did have to rebias the amp though and set the bias lower from around 0.9 mV to 0.7 mV as per the manufacturer's recommendation.
My 5U4G is a NOS specimen so I'm letting it burn in for about 20 hours before I proceed to carry out a more indepth comparison.
You say you rebiased the power tubes after the 5Y3 was replaced with the 5U4. Did you measure the new B+ and calculate the new bias current or did you just set it to the manufacturers 5Y3 current number?
With the 5U4, I would expect your B+ to be considerably higher. You would then be operating the EL34s at a greater power setting, current being unchanged. There may be no harm in doing so, but to really compare rectifiers you should do your comparisons at the same power settings.
My Tube amp has an easy fixed (adjustable) bias feature.
I don't really have to measure the B+. There is a built in resistor in the bias circuitry which requires me to simply re-set it to 0.7mV as long as EL34 tubes are used.
This is because after I subbed in the new rectifiers, from 5Y3 to 5U4G, the bias naturally was changed.
I just had to re-adjust it according to the manufacturer's specs.
Not that it matters, I am currently using the RCA 5R4GY rectifier and it blows away the 5Y3 and 5U4G in terms of sonics. I got back my (previously missing) low end bass along with a warmish mid-range and sonic clarity from top to bottom.
The top-end also sizzles in a pleasant way.
I'm done with rectifier tube rolling for the time being. ;)
Like Tom Bavis says, don't put in a rectifier with a larger current draw. This is designed for 2 amps filaments. So check the data sheets and don't be tempted to use any old octal rectifier. And as stated, your HT will vary - could go up or down, most likely up with the GZ32 and 34.
Don't be too hard on the 5Y3, it's the octal equivalent of the 80 which is a super rectifier and as good as most except exotic mesh plate ones (AZ1 etc. but they're different again, and expensive). If you can trust yourself with a multimeter you can measure the HT, but you'd need to understand the circuit before going inside for that to be of much use, and if you don't I wouldn't risk your fingers in a live chassis.
So look at the data sheets (you need to understand what rectifiers are capable of providing), tube roll with caution from amongst the 2 amp choices, and don't do more than short listening tests. If you hear something you like then get somebody to help adjust the circuit.
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