as someone who doesn't understand much about electronics but craves to build and at the least tweek, I'm looking at upgrading the valves in my amp. It currently uses 4x EL34's, 2x 12AU7's and 2x 12AX7B's. The EL34's are labled Jinvina, the smaller valves just say'china'.
I've read around and it seems like it would be great to come across some NOS Mullard valves... however I don't know what to look for in old or used items so would rather buy something new this time.
The Psvane tubes look pretty fancy with their blacked out glass but what effect would they have on the sound of my amp?
I've got a very 'warm' sounding system and have been listening a lot to my friends 'precise' system and would like a little bit more precsion in my system... is there a valve anyone could recommend?
Finally, I'm assuming changing the el34's will make the biggest difference... am I just falling into the trap of beleiving bigger is better?
Thanks
I've read around and it seems like it would be great to come across some NOS Mullard valves... however I don't know what to look for in old or used items so would rather buy something new this time.
The Psvane tubes look pretty fancy with their blacked out glass but what effect would they have on the sound of my amp?
I've got a very 'warm' sounding system and have been listening a lot to my friends 'precise' system and would like a little bit more precsion in my system... is there a valve anyone could recommend?
Finally, I'm assuming changing the el34's will make the biggest difference... am I just falling into the trap of beleiving bigger is better?
Thanks
Those psvane guys are relentless spammers, which makes me question what it is they're really selling. Fancy packaging is often a cover for shoddy engineering. I wouldn't go anywhere near them.
Your best approach is working with topology and operating points to get things working more like you wish- with few exceptions, tube brand is grossly exaggerated in audiophile legend, whereas topology and operating points have major effects on performance.
Your best approach is working with topology and operating points to get things working more like you wish- with few exceptions, tube brand is grossly exaggerated in audiophile legend, whereas topology and operating points have major effects on performance.
Very likely, this seems to be the way they do their marketing. We've caught them doing that here repeatedly.
The very best money you could spend right now is to buy a copy of "Valve Amplifiers" 4th edition. If you understand how the amps are designed and the impact of different design decisions on amp performance, you'll be miles ahead of the tube rollers. It's going to take some work and study, but the payoff will be enormous.
The very best money you could spend right now is to buy a copy of "Valve Amplifiers" 4th edition. If you understand how the amps are designed and the impact of different design decisions on amp performance, you'll be miles ahead of the tube rollers. It's going to take some work and study, but the payoff will be enormous.
Just trust SYs advise, this book is really more than worth the money! And compared with rolling Mullard tubes, it is dirt cheap
Also, take a look at SYs own articles, they are great reading and education...
Regards the sound..
You would find more difference between something like a KT66 or 5881 against a change in EL34's..or triode connection or true triode.
Then again it depends on the power level you are running...etc
True triode Link:
DECWARE - Article about fake Triodes vs. the real thing.
You would need to modify the amp to get corret bias etc so don't go there yet!
The problem with tubes is they age..so might be better with a few better caps and mods...these are permanent unlike tubes...I have found mullards sound good, as good as other tubes if you get good ones...sometimes people like the sound of tubes that have been run for a long time because they can become warm sounding..emission etc.
As SY says get some learning under your belt and then you will see it in a different light...
Regards
M. Gregg
You would find more difference between something like a KT66 or 5881 against a change in EL34's..or triode connection or true triode.
Then again it depends on the power level you are running...etc
True triode Link:
DECWARE - Article about fake Triodes vs. the real thing.
You would need to modify the amp to get corret bias etc so don't go there yet!
The problem with tubes is they age..so might be better with a few better caps and mods...these are permanent unlike tubes...I have found mullards sound good, as good as other tubes if you get good ones...sometimes people like the sound of tubes that have been run for a long time because they can become warm sounding..emission etc.
As SY says get some learning under your belt and then you will see it in a different light...
Regards
M. Gregg
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Now, no disrespect to SY (really, read some of his posts)or anyone else here at diyaudio, but I got to ask some questions...
And well, being from the same boat of sorts (my electrical knowledge is fairly limited) I can sort of relate to where you are coming from.
What kind of amplifier is it? Make and model would help open up some possibilities to doing other things to improve the sound or if the amp is fine enough, then maybe all it does really need is rolling the tubes. All I can figure out from your post is that it is most likely a push pull EL34 amp (could be a very decent Z-Infinity Z40 or an obscure Chinese made brand that has garbage iron for output transformers and under-rated capacitors), so help us out.
I have to ask this because I have seen 1) some really well built from the ground up amps, 2) some just deadly looking re-furbishments of Chinese made amps, and 3) some old amps that have new life put into them by updating components. And they require nothing but better tubes. You can see a lot of them here in the forums. Knowing what you are putting tubes into also helps with the "precise" sound you are wanting and what you might be getting.
On the flip side, some amps just don't sound all that good with ANY tubes you put into them (there is a problem with the transformers, capacitors, pots, or the build). Those are the ones that you have to attack the schematic and know your calculations.
Simply put -- check your amp.
So let's say everything component-wise is well balanced and the transformers are near perfect for the topology of the amp. The amp is a piece of art and nothing needs to be done to it. It is just the tubes really are garbage. How much do you want to spend? It can get very expensive quickly if you are not careful. Are there any other tube guys nearby to you? Can you take your 60 pounds of metal down the road and audition their tubes in your amp? Or have a few of them come over with their 1.5 pounds of glass and metal to your place, luring them there with an offer of some good beer and BBQ burgers?
Remember, you've checked your amp and it is perfect so nothing will burn out an expensive NOS Mullard matched quad because the transformers were running too hot. Make sure the people who lend you the tubes to roll are cool with this arragement, and as a rule -- you break a tube, you pay for it.
From there you can decide what is what. Do the older nicer sounding tubes actually sound nicer? Or will a set of newly minted and reasonably priced EL34, 12AX7, and 12AB7 tubes do your ears good?
Also, ask the people who are selling the tubes. Go to their websites. Email them if you have a question. They might have one or two minutes to reply to you (some of them actually offer service).
I have gone to thetubestore.com in real life (also they are a sponsor here at diyaudio and I am in no relation partnered with them) and I am lucky to live 15 minutes away. I had sold some old gear to another audiophile, and before I could spend the money on something silly like food and clothing, I decided to buy a couple of tubes for my, "work in progress" project. I got to talk to two guys and one nice lady there and I gave them a price range and told them what I was going to build (they first thought guitar amp at first because I suppose they have a lot of guitar amp types going there). They presented me with three choices of KT88 for my Mikael Abdellah project in my price range and gave me their opinions (on sound, number sold, and customer response). I ended up walking away with a couple of newly manufactured KT88 tubes. I have tried them out already in another diyer's Mikael Abdellah amp and they sound great.
btw... I am still waiting to win the lottery and get a Z-Inifinty.
The amp I have is far from a Z-Infinity. It is a chinese made Ming-Da MC34-A06SE if that means anything to you. I live in Thailand so bought it from here, but I understand that Ming-da have now got a UK supplier and seem to be competing with Icon audio. Ming-da amps are starting to show up in the HiFi magazines with top scores:
The description of the amp says "Custom built audio and power transformers using Zll and H18 long grain annealed and directed steel sheets" - Does that give anything away?
and using "USA made Teflon silver cable for audio signal paths with High-end parts: Philips, Panasonic capacitors, USA made resistors"
The inside to me looks nicely done... but I guess the next stage would be to ask the manufacturer for a schematic for the amp. Really I am very happy with the sound I just have a craving to tweek.... and the point to point soldering makes this even more tempting to me.
I'll try and get a picture of the inside later, maybe someone could have a look and tell me what they think.
The description of the amp says "Custom built audio and power transformers using Zll and H18 long grain annealed and directed steel sheets" - Does that give anything away?
and using "USA made Teflon silver cable for audio signal paths with High-end parts: Philips, Panasonic capacitors, USA made resistors"
The inside to me looks nicely done... but I guess the next stage would be to ask the manufacturer for a schematic for the amp. Really I am very happy with the sound I just have a craving to tweek.... and the point to point soldering makes this even more tempting to me.
I'll try and get a picture of the inside later, maybe someone could have a look and tell me what they think.
I repaired recently a pair of Ming-Da monoblocks, like on the attached picture. Tube selection is like quality of sound was not on the first place; on the first place were visual effects and popularity of selected tubes. But they were performing quite well, thanks to output transformers. They indeed were good for full power from 20 Hz to 20 KHz, despite of high impedance that was needed for 845'th with about kilovolt of B+.
Mingda MC300B-845A
Your amp is different, but made similarly. Both triodes of 12AX7 are paralleled, with common cathode resistor 1.8 kiloohm. Most probably with 1 more tube it looks better, more symmetrical, despite of fancy regime of an input tube.
An externally hosted image should be here but it was not working when we last tested it.
Mingda MC300B-845A
Your amp is different, but made similarly. Both triodes of 12AX7 are paralleled, with common cathode resistor 1.8 kiloohm. Most probably with 1 more tube it looks better, more symmetrical, despite of fancy regime of an input tube.
I can only speak from the ones we have sourced from Grant Fidelity, a quad of EL84 and 2 pair of 2A3. I think Chris also got a quad of 6CA7 but that amp isn't running again yet (a Jolida getting a DynaMutt front end) Very good tubes.
In terms of tube rolling i'd be looking at the front end 1st.
SY, i picked up a quad of Sovtek & winged C from Apex Jr for less than 40 quid, they are serving fine in my DynaMutt.
dave
Like this?
The one schema i found had paralleled 12AX7 driving a 12AU7 LTP phase splitter into a cathode bias output stage. Less gain at the front and some work on the LTP (like a CCS) would probably go a long way...
point-to-point so easier to adjust... and the cheap chinese WBT clone 5-way posts could go.
dave
Attachments
another reason I went back to a 6v6 amp Nos 6v6 can be had pretty cheap still,not the case with EL34s unfortunately and I would never buy a current production EL34 either already wen't through all that with a carvin legacy and x100b and old jcm800 the new ones your asking for trouble some of them self destruct randomly lol
rivers of snake oil are oozing out of this text.....
especially the passage about the "speed". EL84 sounds faster than EL34 because of the smaller outline....WTF?!
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