5u4 vs gz34. Radio tubes are valves.

5u4 vs gz34 5Y3 and 5V4 will also work fine, voltages will be lower and "soften" the amp somewhat. 100 (two tubes are off). Reply. 5AR4/GZ34 which my old pioneer has). Add a fan. GZ33 or GZ37 rectifier tubes have some disadvantages. 00 £15. Hoffman Amplifiers Tube Amp Forum, GZ34 to 5u4m. Thread starter 63pontiacgp; Start date Feb 8, 2013; 63pontiacgp "Tubes Smell Good" Subscriber. Aug 17, 2016 5AR4/GZ34-5DA* - 5. Joined 2003. This is a very popular rectifier to use in place of 5U4, 5AR4, 5Y3, 5V4 and many others. Tube Amp Doctor. It's a free internet. What doesn't make sense is that the part no. Rectifier Valves, GZ34, 5U4GB, EZ81, 5Y3, etc. The engraved Brimars are the least expensive of the lot and they will run you 5-7 times the cost of your Sylvania blackplates. Head Gear Mullard GZ34/5AR4/CV1377 (black base) Black base 5AR4 made by Mullard in the Blackburn, England factory. Previous topic - Next topic. But today I saw a 100 watt Superlead (likely also a JTM45/100 transition amp) with a single GZ34, no ss rectification whatsoever. I don't know, specifically, if the PT in that era AC30 Luckily, the PT was not damaged. By having this information on a chart you can choose a rectifier tube that will best suit your playing style. 1. 7) 5Y3G/B They're all interchangeable within limits. It’s mentioned in another forum post in a different thread that if you use a 5u4 in a Dynaco ST 70 instead of a 5ar4, power is reduced by 50%, e. 5U4 is pretty close to the GZ37 specs without the capacitor In addition, this Groove Tube GT-5U4 works as a suitable replacement for 5Y3, 5Y3GT, and 5Y3GTA, helping boost up power and dynamics. Rectifier tubes mostly work until they don't. Items 1-24 of 27. JJ The GZ33 is not = CV378. YMMV: do your own test. Headphone Amps (full-size) Thread starter Dubstep Girl Start date Dec 10 I've been comparing between GZ34 metal base and Sophia princess, and wanted to share my experience with you guys to see if I'm accurate and Rectifire tubes:- 5U4 GB RCA- GZ34 MullardAmp:- Fender DR Silverface 73Guitar:- Fender Stratocaster 62 CS with Fat 60 pickups by JosephinaEffects- Ts9- Blues The only direct experience I can offer is with the Heartbreaker. 0 Members and 1 Guest are viewing this topic. Both are among the firmest, most efficient tube Jim, There are a lot of rectifiers with the same pinout as the 5U4. This is a great replacement for GZ34 & 5AR4 tubes. Feb 8, 2013 #1 but the 274B will lighten your wallet (and last forever). This will mean increased headroom, but there is a real good chance that the breakup you are hearing is coming from the speakers. Re: GZ33 or GZ37 rectifier tubes vs. I think I might try the thermistor on the rectifier filament as per Eli's To add to the confusion, I've also heard that the PT's used in PR's differed in height between those that took GZ34's and 5U4GB's. If in doubt, go conservative. 9A filament current. I go back and forth between the 422a and WE 274b on my Stratus. 8A compared to 3. I only use the GZ34 in older equipment that require it and either build around the 5AU4/5V3A or damper diodes for new builds. 5AR4 / GZ34 vs. Sag is mainly function of plate impedance at a given output current *not* maximum output current. replacing a 5AR4 with 5R4 or 5U4 adds another amp @ 5v = 5 watts current draw). This is comparing the same amp with a 5y3 & 5u4, which are much closer in sound & feel than a 5y3 & gz34. I actually much prefer Tung-Sol 5U4GB to any other 5U4 type (except the Ken-Rad), though even the lowly Sylvania 5U4GB is preferable to a new-production version, in my opinion. GZ34 (or 5AR4:) Similar, if not identical, the British GZ34 was an ingredient in the original Vox AC30 of the early '60s, while the American 5AR4 was standard equipment in many larger Fender amps. GZ34 vs 5U4 vs Diodes. I previously liked the 5R4 but couldn't take the warm sound and soft treble and bass. I’ll add that a fantastic tube is the KR Audio Riccardo Kron Anniversary Special Edition 5U4G. Didn't most Fenders use a different PT when the change to 5U4 from GZ34 was made to make up for the voltage differences? Does anyone have any insights on this? The major difference IMO is the 5U4 vs the GZ34. On a new NOS Mullard the flashing extends down BEYOND the level of the mica. Martyblackeye. 35 watts/ channel. GZ34 only needs 2 amps. 83. The anp was sparkiler standard with SF values but the trem and reverb were deeper with the BF values. Member. I don't want to risk damage to this amp. There is a metal rectifier, 5T4, (3A) and later get a GZ34 (5AR4) which is 2A, will this cause any problems, if swapped. Every amp and each type of power tube has different limits so there are no general rules that apply universally. 5A of current. Healthy caps, good rectifier. When I asked him about that today, he mentioned he just had those on hand and they were inexpensive. They produce a similar voltage drop to 5U4 rectifiers but require only 2 amps of heater/filament current from the power transformer as opposed to 3 amps for a 5U4. I prefer indirectly heated types (5AR4/GZ34) if the circuit is willing. Have had no problems with any of these rectifiers since getting rid of the standby switch. 9A (for 5AR4/GZ34) to 2. S. The Soviet GZ34 was better than I expected. I’ve used one in a Bob Latino’s sl70 power amp, Modwright pre and currently using one in my Cary SLP05. The PT is wound to compensate for the additional voltage drop across the 5U4GB rectifier tube by having a higher HI-V AC potential from the start. I’ve had great experience with metal base gz34’s. To start viewing messages, select the forum that you want to visit from the selection below. 4µF belastet werden. This 274B vacuum tube's filament draws 2. Add to Basket. The recommended bias setting for the ST120 tubes is 50 mA each for a total of 200mA plus about 25mA for the VTA board. 5A (for 274B) can be tolerated by the amps power supply before swapping the tubes! We know that the 5U4 drops more voltage than the GZ34, yet both schematics show 415 DC at the output tube plates. ) Power tubes Yes, rectifier tubes DO make a difference and you certainly can't go wrong with a Mullard. Yep, they are the same. The GZ33, however, I would say that if your amp can handle a 5U4 (which requires higher heater current than 5AR4/GZ34), then you can probably sub since apparently the 33 will give less voltage at the output than the 34. Z design based on the incredible KT-66 tube originally built by Genelex. A GZ34 can be used in place of a 5U4 with the only concern being that the GZ34 will yield higher voltage to the B+. I'd like to try the new ACME 274B tubes in place of the current 5U4G tubes in my Line Magnetic 210IA Tube question 5U4GB -- GZ34; If this is your first visit, be sure to check out the FAQ by clicking the link above. The GZ34 will be the least voltage drop, equivalent to the EZ81. Joined Aug 14, 2004 Posts 13,175 Location New England. The amp will run but with that much lower B+ its tone will probably Rectifier Interchangeability and it's relation to Clean Headroom. 2CW Yep, they are the same. So I started to poke around various datasheets and I am hoping to gain some clarification. Don't wait to be asked. Octal, IO) K8A, USA 1935 and Power-supply shown. The GZ37 is very tough and handles the 1920uf's of monoblock supply in my amplifiers that have a 5 ohm DCR just fine. Every time. Amplifier Hardware; Bias Tools; Boards and Board Making Parts; Absolutely no advantage with the exception of a CLC type 5U4 or GZ34 rectifier. Damit ist man auf alle Fälle „save“. The Preferred Series 274B rectifier tube is a full-wave rectifier that is very similar to the classic 5U4G. Add to Wish List Add to Compare. View as Grid List. Click to expand My data sheets indicate CV378 filament draws 2. ) Preamp tubes (12AX7, 12AT7, 12AU7, 6DJ8, etc. I preferred the saggy 5U4 to the GZ34. Details; Discussions; Posts; This This is a chart showing the specifications for 5 volt rectifier tubes that can be used in guitar amps. 5R4 and 5U4 are directly heated and so will come up to full power faster than a 5AR4. Fender used virtually the same PT in late Vibro Champs and Princetons. trying to test these 5ar4/gz34 in my tube tester and cannot get any readings whatsover I try both iterations and still nothing These are brand new jj's and I know at least one of them is aok am I doing something wrong? Eico tube tester please advise The 5U4 heater takes 3 amps, so plan for that. Level 2; Posts: 177 ; I hate solid state amps; Re: GZ34 to 5u4m « Reply #2 on: The GZ34 will probably be much cleaner, tighter bass, "faster" feel & response. 5U4GA, 5U4GB, 5AS4, CV1575, 5U4G (large ST tube - electrically equivalent but won't fit in some circuits) 5R4. The GZ34 is an upgrade to the GZ32 and both are rated at 125 mA rectifier current. You'll get about a 20v increase by going from a 5U4 to a GZ34, and another 20v by going from a GZ34 to a SS rectifier. The 5U4 can supply less current whereas the GZ 34 is the same as the 5V4. Logged JohnR. The chart is most useful when you use it as a guide to the relative voltage drops of different rectifiers. It will quickly red plate (overheat) if used as a substitute! testrun. To replace 5AR4 or GZ34 with 5U4G or 274B, you MUST consult your amp manufacturer to make sure the increase of filament current from 1. mvm I have 5U4GB, 5R4GYB, and 5AR4. Other custom wood finishes are available Dimensions: 17 1/2" W, 9 7/8" H, 9 1/2" D Weight: 22 lbs. With "free" comes inpurities. These tubes are taller (5 1/4" high) so that if you use a tube cage they won't fit under the stock ST-70/ST-120 tube cage. It runs hot in some GZ34 - 355 53KU - 352 5U4 - 350 5V3A - 349 5Z3 - 340 My favourites included GZ33 and 5Z3 - top and bottom - as well as 5U4 which was right in the middle. Rectifier tubes drop the B+ voltage by different amounts. That PT won't handle a 5U4, which draws 3 amps of heater current. IF this tube you have has a current draw of 200ma, it is closer to the GZ34/5AR4 sepc of 175ma than is a 5U4, but I still would not advise using it in place of a GZ34. I like the indirectly heated cathode and the extra warm up time of the GZ34. I don't think they made a major difference. Auch wenn diese Röhre kaum belastet wird, sind bereits 10µF ein schleichendes Gift My amp is used 5AR4/GZ34,can I replace with 5U4G or 274B ? Audiogon The world's largest high-end audio community. Butyou won't see 20 volts of drop from a 5Y3GT vs 60 on a 5Y3. Drop-in Equivalents & Substitutes: 5U4. £19. , 17 watts/channel vs. Forums. I heard about switching the GZ34 rectifier tube and replacing it with a 5U4GB. 5AR4 vs. g. GZ34 is the English designation and 5AR4 is the American designation for the same tube. The drop in B+ voltage is significant - with a GZ34 and a 47 ohm, your B+ is dropping by 35V. DIY Central. You're currently reading page 1; Page 2; Page Next; Show For 5AR4, 5U4, 5Y3. What's the difference between the 5R4W and the more popular 5U4G, 5AR4? I heard from tube (shop) keepers that if the amp uses 5R4W, the 5U4G and 5AR4 tubes will be compatible. At 100 mA current thru the valve, we have app. 0 GZ37 350 1000 450 388 37 2. - Thom I'm guessing that the GZ34 being indirectly heated warms up slower at switch on than the power tubes so the B+ rises to the operating voltage without overshoot but with the faster warm up 5U4 the B+ rises to 540V before the power tubes start conducting to pull it down. Cheers! cbg Rectifier: 1 - GZ34 Controls: Volume, Treble, Bass Configurations: Head Colors: Black. You can use a 5u4GB as it is rated at 275mA. Print. The PO put in the JJ GZ34's in specifically for the slow start feature of the GZ34 to save fatigue on the output tubesno other reason. Hence, I've been cautioned against using it since it *might* operate some of the downstream AB568 circuits tend to like 5U4GB rectifier tubes. Have standard recommended parts from the tubelab site and using the same Hammond transformer. They are far 5Z3P vs 5U4G vs 274B. It´s the absence of bias readjust when the rectifier tubes are activated. Thanks for the clarification. Eine 274B darf nur mit max. While it looks like a GZ37, the GZ33's electrical behavior lies between that of the GZ34/5AR4 and the GZ37. Welcome To the Hoffman Amplifiers Forum January 07, 2025, 11:23:20 am: Welcome, Guest. You're a YP. A more important question is "Will the PT handle the extra filament current the 5U4 requires?" 5U4 needs 3 amps. Deeee. Since that one subs for a ton of types, I'd guarantee its different on at least most of them. This won’t be a problem if all your coupling caps are rated for the voltage drop you’ll get on startup. 8 5U4GB 275 1550 450 375 50 3. Would the big coke bottle 5U4's sound any different? What about the GZ34 rectifier tubes? (I have heard you may have to up the fuse rating to run May 16, 2008 #2 The difference between rectifiers is not tonal. This would make sense, since the PT used with the With luck, the OP has been able to discern an answer to his 5U4GB vs. I have several components that it explicitly stated that I can use a variety of rectifiers in the same family: 5AR4, 5U4, 5Y4, 5Y3 For instance, the 5Y3 (aka the 80) has much less current handling than a 5AR4 (GZ34) or a 5U4. The 5AR4 or GZ34's are similar, but sounds a bit more 'rounded' than the 5AS4. There was a blacker background using the Glenn adapter on the WA22. If it was me, I would They are now pricy but their sound is often better than the GZ34's or 5U4's and others IMO. There's a few minor component changes in the preamp. 5R4 rectifiers (any suffix, GY, GA, GB, GYB, etc) are pin compatible with 5Y3, 5U4, 5V4 and 5AR4/GZ34 rectifiers. Logged A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. In my new Deluxe Reverb build, I was using a JJ GZ34S. But just try changing the rectifiers first and see how you like it. You may have to register before you can post: click the register link above to proceed. GZ34 drops about 10v under load, and 5U4GB drops about 50v. The centre going to ground. Also GZ34 like up to 60uF reservoir cap (compared to the 5U4G @ 40uF) to get the maximum benefit out of them. Radio tubes are valves. Virtual Systems. The GZ34 and the 5V4 are both rated for 500 volts rms but the 5U4 is rated at 350 V. Bluebook The right price. Oct 17, 2008 #14 ; There are many variants and equivalents for the 5U4, not all of them are drop-in substitutes though. This won’t be a problem if all your coupling caps Less current draw with a 5AR4 vs a 5U4, but the 5AR4 has less voltage drop and is slow start. 20uf is recommended first filter max capacitance for the 5Y3 but 40uf is common. When going to these smaller rectiifers, one would want to take note of the filter caps. In all three cases the metal base GZ34 made the most significant positive improvement to SQ I’ve experienced. If you have an extension cab to try, check it out. Firestorm wrote:The power transformer will certainly support the GZ34, which draws less heater current than the 5U4, but the GZ34 will raise the voltages in the B+ supply. sunil. of heater current, which is what a 5U4 draws. 00+ . The difference is noticeable, not only in audiophile gear, but even in old tube musical equipment like Fenders, Marshalls, etc. Volunteer; Posts: 14269; testingtesting » Gallery » Systems; Re: Running 5U4's versus 5AR4. SIGN UP LOG IN. L. You'll get 30º margin back. 5U4G / 274B: A 5AR4/GZ34 requires 1. Please login or register. I found the 5U4's to Can I use either the 5U4GB or GZ34 interchangeably? Is there a reason to use one over the other? Pros/Cons? Any advice or suggestions welcome. And yes the advice of not turning your amplifier back on immediately should be followed. Equipment Forums. So maybe the Mark V would tolerate the 5U4GB in the 45 watt mode. I would like them a lot but I've had 2 The 5U4 and GZ34 are pretty much equal but the 5U4GB will drop the B+ output voltage by about 40 volts. The PT in that amp was cranked up a little when Fender went to the 5U4, so you'll likely see something around 485VDC on the plates rather than the 460VDC on the schematic when you I suppose some JTM50/JMP 1987 transition thing. General Info: "The Route 66 is an all original Dr. 5Y3/80 vs. 5V4 vs. The world's largest high-end audio community. Solid State Rectifier. They are much more expensive than a GZ34 2. The problem is not the use of 5U4. I don't know if a GZ33 can stand a 60 μF. They do come up instantly, but a 5U4 and other direct heat types come up I would prefer to get another GZ34 even if the PT can handle the 5U4. Voltage drop reflects plate Z. This current draw makes it acceptable for many amps originally designed for a 5AR4/GZ34 tube. 5U4 vs. This one is from the 1960s and was branded as IF one wants to run a different recitifer tube in either case---whther the orignal is a 5U4 or a GZ34, the 5V4 mentioned above is a better option for replacing the GZ34and a 5Y3 will yield even lower voltages. It can often but not always sub for a 5AR4. 2017-04-24 5:51 pm #48 2017-04-24 5:51 pm #48 zman01 said: Sunil, The GZ34 is an example of a typical high current rectifier for small equipment use. ) They work, but usually the output voltage isn't the same. My 1965 Super Reverb has a 5U4GB and that sounds much better than a GZ34 in that particular amp. 2) 5AR4/GZ34. The cathode of the rectifier feeds the first capacitor known as the tank capacitor, usually between 4 and 8uF oil type. jaymanaa RIP 1961-2018. 6V6 plates at 460v, and bias about 15mA each tube. I thought I'd try a 5U4GB to The 5V4 is like a GZ34 w/ indirectly heated cathode/slow startup, but has less current carrying capacity (175 mA if I remember right). You can substitute lots of tubes, as long as you observe the peak inverse voltage and current limits, and it's good to pay attention to filament current draw too (e. a GZ34. The transformer HT winding would be centre tapped. Merch Rep the community and hobby you love so much. I've tried RCA and National Union 5U4G and find them quite similar. Feb 9, 2013 #4 Epay for the WE tube, they GZ34/5AR4s drive 40mfd caps all the time - that is the first stage of the power supply in the Deluxe Reverb, Super, Pro, 5U4: 405 volts (75%) 5AR4: 425 volts (100%) Not sure if that was relevant or interesting, but it was for me. In fact, he said that early MC30's he's seen came with the RCA 5U4g's (big Dubstep Girl's Massive 5AR4/5R4/5U4G Rectifier Review/Comparison! I have been wanting to create this thread for quite some time now, since Home. A 5U4 should feel more spongy and have a softer attack than a GZ34. Virtual Systems Let the world see what you've built. There are few vendors for these tubes 3. Would rather not shell out big buck$ for the 5AR4 if I can avoid it. However, I read warnings that this could stress the power transformer. This would make sense, since the PT used with the 5U4GB would be wound hotter to achieve the same B+ and also be rated for 1A more heater current on the 5V winding. It's in the amp's feel and attack. Many guitarists and bassists also fall back on this GT-5U4 for swapping with the stock GZ34 I've looked through the forum and not seen much in the way of a direct conversation comparing pros and cons of using a solid state rectifier in your tube amp vs the original tube type (e. Tube GZ 34 or Röhre GZ34 ID3410, Full-Wave Vacuum Rectifier, Octal (Int. Joined 2020. Is it going to make that much of a difference in the sound of your amp? If you are going to upgrade your amp, is that the best bang for your buck? I know all the attributes of the tube but still, did I miss something ? I have not been able to find a definitive answer this question so maybe a tube amplifier expert on this site can clarify for me. You can easily swap those - FWIW. The amp does use a 5U4 either GA or GB. If you hate fans, find a rectifier with a lower filament load that gives you the sag you crave. They exist. 0 Biggest change in princeton reverbs over the years was going to a 5u4 from a 5ar4 with the same PT although current draw will be 1 more amp. In my Allnic phono stage it’s another world, far better than any 5AR4 or 5U4G I’ve tried, including the vaunted Cossor CV575 from the early ’50s. ADVICE: Let that transformer temperature help guide you in your use of a 5U4 vs. . 9 - 17 - 250 - 450 - low Vdrop 5U4/5Y3 The difference between them and people like us is that while they can go find a new amp when they blow theirs up we can't. 3) GZ37 (3 amp filament current) 4) 5V4G/A (Possibly lower if plate current of the power tubes is high enough) 5) 5U4/G/A/B (3 amp filament current) 6) 5R4G/A/B. Page. I think this was different speakers, but same amp & guitar. Rectifire tubes:- 5U4 GB RCA- GZ34 MullardAmp:- Fender DR Silverface 73Guitar:- Fender Stratocaster 62 CS with Fat 60 pickups by JosephinaEffects- Ts9- Blues The modern-production GZ34/5AR4 seems to be less than perfectly reliable, too - so many of us here use "damper" (efficiency) diodes - either 2 tubes in a full-wave rectifier, or paired with (eg) UF4007 SS rectifiers in a hybrid bridge. The WE 274a and 274b is superior though. 9 5V4 175 1500 375 400 25 2. Also a Brimar 5U4 engraved running at $51 and counting for a single with less than a day to go. cap. GZ34/5AR4 question through the meaningless drivel you and a few other irrepairably damaged individuals perpetually vomit up at every opportunity. Bei der weniger „hübsch“ aussehenden GZ34 darf es maximal 60µF sein. 2024-06-23 11:10 pm #1 2024-06-23 Have tried GZ34 and 5U4GB. A 5Y3 is a very droppy tube. Our 5AR4 Rectifier Tubes have an excellent & reliable response with a strong, dynamic response sound. Started by MikeViking, December 30, 2018, 11:12:31 PM. GZ34 vs 5U4 vs Diodes Thread starter Martyblackeye; Start date 2024-06-23 11:10 pm; Jump to Latest M. for The MC30's came with the 5U4. The GZ34 can suppy more current than either the 5V4 or 5U4. JUST DO IT! blues man. Bei Verwendung gerade dieser Röhre findet man sehr oft „nur“ 47µF. The 274B were hitting $750 or so and still going. New posts Search forums. The GZ34 is extremely popular and is a current production item with multiple makers so good long term availability Beware as other have mentioned about the current draw of the 5u4 series over the GZ34/5ar4 Cheers. Russian 5Y3 will drop less voltage than NOS. It´s a good relation (-10% aprox. This then feeds the second capacitor through the choke. I'm curious about giving it a spin in my AC30- '90s Korg-era RI, 6 input NMV with Blues. Has anyone tried this mod? Is it safe? Any recommendations for achieving more The GZ34 is equivalent to a 5AR4, specs are 2 Amp @5V heater, 60uF max 1st Cap, good for about 160mA DC with an internal resistance of about 175 Ohms causing about a See chart below. With diodes you will read 445 volts approximately and with 5U4, about 400 (it happens in the versions for Europe with 230V). My issue today is that I don't have a 5AR4/GZ34, but I do have both a 5R4GA-JAN and a 5U4GB. 0 - 1. You can run EL-34s with the 5U4GB, but the manual says only at 60 watts vs. Audiogon. Starting with a 5U4GB, Sovtek's datasheet (linked HERE for convenience) states: The Weston Tempest (old KT88/ class A version) currently use 5R4W. This makes them good substitutes for the other rectifier types when different output voltage is desired. The Mullard GZ34 is widely regarded as the best of those tubes. 5A (for 274B) can be tolerated by the amps power supply before swapping the tubes! Pretty useful thing. You may need better speakers than a phone to hear the difference, but the 5y3 basically stays That PT won't handle a 5U4, which draws 3 amps of heater current. Rectifier tube (GZ34/5AR4, 5Y3GT, etc. GZ 34's and 5U4's will stand up to higher 2) Would an SS rectifier that draws nothing give me even more power than both 5U4 and GZ34, and give even more potential for cleaning up that bass department? Likewise, In a tubed preamp, like my Dynaco PAS, what kind of results Dubstep Girl's Massive 5AR4/5R4/5U4G Rectifier Review/Comparison! (Rectifer Tube Rolling thread) Home. GZ37 vs GZ34 rectifier tube. Results 5AR4/GZ34 250 1500 450 415 10 1. I found that the GZ34 and 5AU4/5V3A were equally good sounding, but the 5V4 was poor in comparison. I recently acquired an older Sylvania 5U4 rectifier tube. Quick question. I/P filter, like the GZ34 can, but I doubt the 40 μF. Thanks! Register to hide this ad robert_kc AK Subscriber. Dyna ST70's beat the rectifier into the dirt. This is a 5U4; 2A3 / 6A3 / 300B; 211 / 242 / 845; American 5 Tube Set; Parts & Accessories. The GZ33 draws 3 A. The 5U4GB rectifiers draw more current and has more low wattage breakup than the GZ34/5AR4 in lower wattage amplifiers so maybe try that rectifier tube. -User Name Yes. The Mullard GZ34 has a hole in the guidepin and the upper micas have 5 teeth per side. What happens is a GZ34 at start up will source so much To add to the confusion, I've also heard that the PT's used in PR's differed in height between those that took GZ34's and 5U4GB's. 0A for a 5U4 so 378 should be *safe* in any 5U4 app from that perspective. Here's the list of the most common guitar amp rectifiers in order of most to least clean headroom (highest to lowest You can't use a 5y3 since it is rated at 125mA max. Is a used Mullard GZ34 really worth $140. 5U4 drops more voltage than a 5AR4/GZ34, but less than a new production/Russian "5Y3" which drops less voltage than an A GZ34 will raise the B+ by 30V or so and will definitely stiffen up the sound a bit, and so you may want to re-bias the 6L6s to run a bit cooler. The GZ37 is = CV378. I understand that the GZ34 is about 50 ohms internally, so a 47 ohm is getting it to intermediate with the 5U4, which is reputed to be about 150 ohms internally. Mullard GZ34's, manufactured in the Blackburn plant, have a well earned reputation as the best sounding and longest lasting. I'm sure Mesa will sell you their brand of 5U4GB, so the real question is if the amp design will accommodate the If this is a single rectifier amplifier, a GZ34 is much closer to what it likely wants in terms of current available. My own EL34 amp rocks a pair of 5U4GB rectifiers to provide ample 5U4G: A relatively firm rectifier often found in mid-sized Fender blackface and silverface amps. On a thread of mine from April 26, 2022, vampwizard said of the AO-43 PT: 5AR4 / GZ34 vs. I'm aware of the voltage sag and decreased output I'd get from replacing the GZ34 with the 5U4. 5U4 limit is a problem. Thanks! Feb 2, 2011 #2 ; muchxs Doctor of Teleocity. Use the 5U4GB when I want to lower the voltage. Interesting results. dutch or uk made real deal old stock gz34’s are The power transformer is wound for a 5U4GB rectifier which means it can handle the extra filament current of the 5U4GB. A push-pull EL34 amp will run the ever living snot out of a single GZ34, and it will make a 5V4G scream for mercy. For what it is worth, I prefer the Ken-Rad 5U4G, for its superior dynamic clarity. provide a higher supply voltage to the rest of the amp circuitry since the voltage drop across it is less than the 5U4's. Meines Wissens ist die russische „Black plate“-Variante eine 5U4-B. 180 The 5U4 has a lot of series resistance that limits the peak current so will tolerate too much input capacitance better than the low resistance gZ34 in my experience. Subscriber. It is indirectly heated but the cathode is tied to one side of the heater. No need to replace it unless you are getting low B+ readings or other symptoms. I was surprised at the results. Both are excellent tubes. wbyjjj rklg ssdzo ofa llcbv ton saq eivlbqp cqayjl vmy aafh edasdj hxvwhb bifis dqpdd