xxJPMxx
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Posts posted by xxJPMxx
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In general, I agree with this, although, not really a Dynaco MKIII clone; however, most of the forum history of the development of the VRD front end has been deleted along with a certain 30,000 forum posts.
I didn't follow those threads so I suppose I missed out. Clone is probably not the best word since there are gross differences, maybe a tip o' the hat is what I should have said. The similarities are there though, three stage Class A/B Ultralinear amp using KT88's, high open loop gain to employ a healthy amount of negative feedback. They even look similar to the Mk III which is why I used it as an example is all. Overall a pretty Classic design, tried and true.
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I'm guessing Schu doesn't spend much time in high radiation areas, like space.
Maybe he should, being a Federation Officer and all.
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why any tube amp over a good/great solid state amp...
Silicon is for the masses because of the ease and cheapness it can be produced at, that's it. Tubes are technically superior. NASA and the military still use them because they operate just fine in high radiation areas like space. Also they are faster, they can operate in the teraHertz region. Silicon has greater limitations.
So I ask you Schu why would you settle for ordinary cheaply mass produced silicon junk when your stereo can use the superior technology.
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My opinion is that they are good looking American made Dynaco Mk III clones. I find also that a lot of people either find that the low powered amps either don't have enough power or they are just unwilling to jump into an amp with low power for fear it won't be enough. Craig's amps a good compromise of going tubes and still getting high power, low distortion and good damping which is what SS is known for.
Personally I acquired mine from a local audiophile that didn't want to put the money into it needed for repairs. He made me an offer I couldn't refuse. I fixed her up and have been listening to it for the past few months, it's a good solid classic sound and design. The actual topology is very similar to lots of Hi-Fi amps from that era, think of the Mullard 5-20 which I built and too has a very SS vibe. I am not saying that's a bad thing either. A tube amp or any amp for that matter with plenty of power and good specs is what Hi-Fi is about. Low distortion, good damping, lots of headroom is what makes the VRD's what they are.
I sold it because it's too much of an amp for me, I am happy with low powered triode amps that run cheap tubes.
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Clearly you hear a difference between the two different power tubes so it appears they are different. For anyone more familiar with Chinese tubes than I maybe you can help me out here.
Here is the datasheets from Shuguang factory:
My problem is they claim the EL34b is a tetrode and the 6CA7 (EL34a) is a pentode as it should be. But if you compare electrical characteristics and also the graphs in their datasheets they are identical. They even show a third grid for the EL34b connected to pin 1. The graph also says g3=0 for the EL34b.
Most likely the EL34b is a tetrode but for some reason the datasheets got mixed up with the wrong data.
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I actually meant rectifiers with the 5AR4 tubes.
Oh okay that makes more sense
It did sell to a forum member so that is a good thing!! Great deals don't hang around for very long, that amp sold 2 days after I listed it. We waited until after the holiday to ship and I just got around to updating the thread. I had lots of offers which is clearly a testament to the amps reputation around here.
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I guess Schu can forget about my morning post below as I just saw this afternoon post where the stereo VRD amplifier is now sold too.
Hahaha!!! Shu missed out on a good deal then!!
two power transformers for the mono blocks vs the stereo channels sharing a larger power transformer while still having separate voltage regulators for each channel (separate regulators, the same as the mono blocks), and the stereo version is heavier than one mono block given everything is on one chassis.I just want to mention that yes the Stereo amp shares the same power transformer and rectifier but splits into two separate choke filtered supply rails for each channel. There is no voltage regulation. I am pretty certain Craig doesn't have any regulation in the Mono's either unless he changed his design lately.
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The amp is SOLD.
Thank you all for looking.
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Hey Jim, thanks for the kind words. What tubes are you having the best sound with?
I will be looking forward to getting the Sansui. It will most likely need some TLC which I am more than happy to provide
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My opinion is that the driver is usually the weak link. Music has transients. We know the solid state guys just like to use huge wattage power amps. Tube amps, especially SET are low power so high power isn't really an option. The AC coupling from driver tube to power tube causes so many issues with these transients. Direct couple a Source follower to a power triode and oh baby!! . Old school amp designers that knew this used interstage transformers, but they are not as good as a source follower. Music with heavy low end transients are the problem so I advise you diyer's to try it, you won't go back.
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So would my amp do better with tighter bass than what we have in it? Just curious.
Nope.
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All good!!
I just wanted to make sure you weren't trying to blow stuff up -
Okay that makes sense you are reading voltage at a mV scale. So they probably have 10 ohm current sense resistors which would convert to 50mA using ohms law. When the amp is powered off you can check this resistance by setting your meter to read resistance.
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I bias them at 500 mA
I highly doubt that.
What's the difference in EL34 and KT150?Well the name would imply that one is a kinkless tetrode and the other is a pentode. BUT the KT150 is in fact not a kinkless tertrode as the name would imply, it is a pentode just like the EL34. I don't know why they market it as a "KT". The difference? The KT150 has about 1/3 of the plate resistance compared to the EL34 giving it a lower Z out, hence the tighter bass.
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Do you have a powered subwoofer?
I built myself a high powered SS stereo amp for parties and what not, it was driving Cornwalls. During parties people liked to dance but the higher level in midrange and upper frequencies were trouble sometimes, people can't talk and what not. So then I turned the volume down and boosted just the low end through an EQ, much better results. The EQ was on a Soundcraftsman preamp. People can feel the beat and dance but still talk. I mean it's still loud but you really only need low end to shake the walls. What I now have better results with is just actually drop the lows going to the main system and use a separate high powered subwoofer to supplement. You can't really tell where the bass is coming from, people will look at my Heresy's and say those things pump out bass and I am like nope, I shut the subwoofer off and things tame down pretty quickly.
So yes two amps is better than one.
If you don't have a separate subwoofer I believe the only pair of speakers you have that you can bi amp is the RF-3's. Some of the more knowledgeable speaker guys will chime in.
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$140 plus shipping and you are only in it for $200. Someone like myself can assemble and fully test it including tweaks and a few upgrades probably run another $200. So $400 isn't bad for a tube amp!! I had my doubts on these kits but they perform quite well for the money.
If you can get Maynards amp I would do that but this is a viable second option.
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In case anyone is interested, the amp Jim started this thread about is now back in my possession. If anyone is looking for a terrific SET, drop me a PM and we can discuss it.
Contact Maynard, I took that quote from this thread: https://community.klipsch.com/index.php?/topic/161069-is-this-anyones-work-near-me-fs-flemington-area-57500/
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A$$-ault and battery
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I think it's a good idea to have another set of tubes around anyway. My feelings are the the 6W6's in the Genesis will be fine at moderate listening levels. Let's assume that toolshedMatt's info is correct w/ 250V at the plate, and lets also assume the Zener is in it's linear conduction region and dropping the screen down to 150V. You can see by the average transfer characteristics that when driven to full power (grid 1 voltage -4 and approaching 0v) the screen current will be 10-15mA. Multiply that by 150v and you have 1.5 - 2.25 watts! The 6W6 screen dissipation rating is 1 watt. Maynard and my concern for tube life and longevity are not unwarranted. Again if you are just casually running the amp the tubes will be fine. If you want to crank the thing frequently using different tubes would be prudent. I am sure toolshedmatt has gone over this with you but just in case he didn't the more you know the longer your tubes will last.
Here are the average transfer characteristics for a 6W6: **make note that a pentode's plate current is more dependant on screen voltage than plate voltage. I like pentode mode but usually only if the screen has a stiffly regulated supply.**
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That Chinese amp I posted is a pentode run amp too. I was thinking of adding a switch to run triode/pentode but everything is on a PCB so it wouldn't be as easy as it is for a point to point amp like yours. In the future you could possibly discuss with toolshedMatt about adding a triode/pentode switch to your amp, it should be fairly easy to do.
Did you order the Tung-Sol 6L6G's? I have some really nice GE and RCA black plate 6L6GB's that sound great in this amp but I too like the look of the 6L6G bottle. I had some Sylvania 6L6G smoked gray glass that I sold to a friend before I had this amp that I wish I never did, they would look boss in the amp.
They looked like this.
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...now wait a cotton pickin' minute - you are saying that I can nearly double the power output by going to the "Big Bottle" 6L6G? OMGosh!!! what have you all got me into here???!!! WooHoo - bottle tubes on order - geeze already rollin'
Hi Matt, are you talking about the 6L6G made by Tung-Sol in current production? That actually had 6L6GC electrical specs but will still work fine great for you. I got a Chinese Shanling STP-10 that I run those tubes in it and they look really nice. Best of both worlds, the looks of the 6L6G and the up ratings of the 6L6GC variant. And yes you will probably double power but only expect a slight volume increase, it won't be night and day is all I am saying. It looks like from the pictures that ToolshedMatt gave you different 6W6s?
Here is the amp I got for $250. It had a minor problem which is why I got it cheap. It's all fixed up now and been running those 6L6G's for years.
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Hey Jim
Buying from a company that mass produces gear the instructions given makes more sense now. They purchase tubes in bulk install them in the device and turn them on for a quick quality control test and that's it.-
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All I do is listen critically now, I am a musician what can I say.
When I was a child my mothers favorite band was The Beatles. Needless to say I hated them from having to hear it almost everyday. Then I got a guitar and started studying music........and smoking dope
Ah now I get it!!! Those guys are genius no matter if they suit your musical taste or not. From 20 years of music theory and ear training I can't just listen to music anymore, it doesn't happen, I don't know if it's a curse or a gift. Even intense improv music I just sit there and analyze the scales and time counts. Same with gear, he switched to the neck pickup or he boosted the treble or blah blah blah I ruined music for myself
Ah now I get it!!! Those guys are genius no matter if they suit your musical taste or not. From 20 years of music theory and ear training I can't just listen to music anymore, it doesn't happen, I don't know if it's a curse or a gift. Even intense improv music I just sit there and analyze the scales and time counts. Same with gear, he switched to the neck pickup or he boosted the treble or blah blah blah I ruined music for myself
Why VRD's
in 2-Channel Home Audio
Posted · Edited by xxJPMxx
Richieb, joshnich, Mike, or anyone with VRD's what power tubes were you guys using in your VRD's? I have been using the Penta Labs KT88 which I believe were made in Shuguang. I would love to have a quad of original G.E.C. KT88's.