 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
135.245.8.2
In Reply to: RE: re-tubing Ming Da 34AB posted by daRRski on March 25, 2010 at 21:19:13
did you upgrade the coupling caps? if not, this will be first step to considerably improvement for this amp. I do not buy the argument given by the guy below due to circuit. tube circutry of PP EL34 amps had been around over 70 yeears, chinese had been making PP amps for over 70 years though....
if you wish I can forward a link contains over hundreds of amps circuits by China in the past 45 yeesrs.
Follow Ups:
Hi
Thanks ....what caps would you recommend ?
due to circuit. tube circutry of PP EL34 amps had been around over 70 yeears, chinese had been making PP amps for over 70 years though....
if you wish I can forward a link contains over hundreds of amps circuits by China in the past 45 yeesrs.
Just because they have been building amps for years means NOTHING.
Most of their circuits are blatent copies of often poor western circuits, executed with poor quality parts.
My partner in Australia is doing good business rebuilding these and other Chinese amps with a decent circuit, He uses the original Chinese parts, even their tubes, just a better circuit with great reprted results.
If you are happy with their designs, so be it, we are not!
Regards, Allen
When dealing with Allan’s agent in Australia, I was offered a series of upgrades to my Jadis DA60.
I was told that the circuit design of the Jadis was not great, and that I would expect to hear considerable improvement from the upgrades (particularly fitment of their Linearity Enhancement Module – see link).
I declined.
The DA60 is the best sounding integrated I have heard. In addition Jadis have some reputation in the world of valve amplification.
I wonder if there is any valve amp that where the sound of the amp, the integrity of the design and the reputation of the manufacturer would suggest that things are better left alone?
Huh?
If you had had your Jadis worked on and didin't like the result, then you would have something to say, and I would support you saying it. But as all you got was some promo, how can you make any intelligent comment on Joe's work?
The Jadis may, or may not , sound great, but theoretically they are all flawed from a technical point of view - using a low gain high current tube (ECC82/12AU7) as the input tube, and a low current high gain tube (ECC83/12AX7) as the driver tube for the output tubes.
The 12AX7 has no chance of correctly driving even the EL34 tubes in your amp - let alone the string of KT88s in their larger models. This results is quite some frequency roll off in the high end, which is easily corrected by simply exchanging these two tube types, and a few associated resistors.
I don't argue you being happy with the Jadis, but not everyone is.
Regards, Allen
When Douglas Chu imported Jadis into Australia during late 80's and early 90's I was the Jadis service agent.
The Jadis are the most quirky of all tube amplifiers I have seen over a period of thirty years plus. Allen describes accurately the very limited bandwidth they have and recall working on the Jadis 500 monsters that kept blowing up. These were so big and heavy I had to lay down a carpet on the floor and work on them on all fours. First time I felt like a motor mechanic. For an amplifier that was rated 500 Watts I recall getting less than 5 Watts at 20KHz. Also they were running high tension that often went over 820V. We managed, and I admit it took several goes, to tame the beast and make it reliable. WE ended up buying a bunch of Manley KT90's as they seemed to tolerate the odd conditions better.
The other odd thing that it used was combined partial cathode and partial (so-called) fixed bias - also found in many Jadis amps but thankfully not all (look for Standby/Operate switch as a give-away). It's hard to explain but the fixed bias is fed from a high value resistor into a capacitor that gets charged. It's takes a long time (a long time-constant) during which the output tubes are exposed as the cathode bias resistor will be the wrong value. If the two are not synced, only the incomplete cathode bias cannot prevent the output tubes being bias too hard. The result is as one DA-60 owner experienced (Audiogon):
"I bought my Jadis DA60 from new about five years ago. Over the last three years the amp has blown two output transformers. The ..."
I have only had one single unsuccessful attempt at fixing ONE Jadis amp (and I was willing to persist). Forgive me for my non-infallibility.
BTW, since starting to use 10R 1/4W fusing resistor in cathodes of power tubes, I have not lost a single transformer, NOT ONE!
So if the fuse resistor blows, that is a real inconveninence (and rare), but that may just have saved you a big wad of bills.
Cheers, Joe
PS: As for mods, I have often DISCOURAGED mods to certain tube amps. Other times I have been approached as a last resort to help a particular amp that had consistent realiability problems. Rarely did I not succeed - so I shouldn't be blamed for some reallly botched designs. Like the VTL amp that turned out to be Tetrode and not Ultra-Linear as the badge on the front panel so proudly announced. With 600V B+ and the Screens of the 6550's directly to it... it blew up regularly. Want to hear other stories? Like a brand name British Tube amp that ran 85mA Bias and nearly 50 Watts on the Anodes. When I was finished with it, only then did it become reliable - and it was NOT modded, just fixed.
"Never express yourself more clearly than you are able to think." Niels Bohr 1885-1962 (Einstein's favourite wrestling opponent. "Einstein - stop telling God what to do.")
I did take my amp to Joe for repair - not modification - on your recommendation. And I didn't like the result.
I am in fact running Genalex reissue KT88s in my DA60 and they are driven very well indeed.
But the inaccuracy of your criticism of my amp illustrates my point. People offering modifications will often find a way of criticising a design. That criticism is the first part of the sales process for the mod. In my view that must cast some doubt over the validity of the criticism, as there is at least some chance that it is levelled to simply make a dollar, rather than because it has any validity.
Now there is nothing wrong with people selling stuff. I simply suggested that people would be well served to exercise caution when deciding whether to upgrade or not.
Here are what would be readers take from your posts here:
1)I, Allen Wright, not shilling even though I have been doing this for years. Please do not banned me here;
2)The tube E34 PP circuitries are still not exhausted yet. There are still new “designs” there. We, Allen Wright and partner, come up new circuit for the PP EL34 amp. (Keeping in mind there are only four components in the tube PP amp: tube, resistor, capacity, choke/transformer, and wires.)
3)Our new design is far better than Chinese’s
4)We are smarter than 1 billion Chinese’s for sure.
5)All Chinese’s circuits were copied from others, and because that they are crap.
6)Our products are better (Allen’s mods services), you actually can hear a difference because our new innovations (new "design").
hey-Hey!!!,
There are all sorts of ways to make a poor tube amp. Do please post this link you spoke of documenting circuits employed by current Chinese manufacturers.
Just for the record, I don't care where you're from; it is quite possible to pick either a good circuit or a bad one and build it with either sufficient parts or poor ones. As far as commercial gear goes, there seems little of it done with the thoroughness and overdesign that DIY is capable of.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
You are obviously a Chinese manufactuer, why don't you share what your contributions have been to the industry...
No, I am not Chinese manufacture. Shall I? Sure, I wish so.
But I do not want be a person who trashes Chinese’s products and accuses Chinese wrong doing on one hand, while living on mods services on Chinese products on other hand.
No, I do not want to share my contribution here.
> > But I do not want be a person who trashes Chinese’s products and accuses Chinese wrong doing on one hand, while living on mods services on Chinese products on other hand. < <
I have never made a penny from working on Chinese amps, and don't really intend to start as I have throughbreds to build and work on. I have worked on one, as a favour to a friend, and the improvement was tremendous. But I have inspected a lot, and my opinion stands.
It's my partner in Australia who has a good business correcting the basic errors in Chinese amps - and his clients are very happy with the results.
Regards, Allen
> > You need to read my post better! < <
OK, lets read your posts very carefully and highlight those your own words here:
“...I have worked on one, as a favour to a friend, and the improvement was tremendous. But I have inspected a lot, and my opinion stands...”
You said you actually worked on ONLY ONE Chinese amp in your life!!!!! But you “inspected” a lot. First of all, no one will believe such statements that one “inspected” a lot of Chinese amps, but only worked on one. Secondly, even one may make your statements a little weaker, it is fair for one to conclude that you actually never worked a Chinese amp at all (not even one).
Now take a look at your others:
“It's my partner in Australia who has a good business correcting the basic errors in Chinese amps - and his clients are very happy with the results.”
“Most of their circuits are blatent copies of often poor western circuits, executed with poor quality parts.”
“It;s not juat my designs they ripoff...”
“I consider we build state of the art gear, in line with, say Ferrari, and I guess I get a little upset with people buying cheap stuff and then accusing good tubes as being the problem.”
If I read you correctly, you were based on your friend’s experiences and hence accused Chinese here. Frankly, I am puzzled how can you still be allowed here as an Audio business owner. You should have been banned a long time ago.
...because I add value in giving much good advice to those with serious questions, based on my 40 years of hands on experience. Seems like you are here just for the joy of arguing.
Regards, Allen
You are joking, right? or you think all the readers' IQ are below 40?
It does NOT matter how much "contributions" you had here, if you broke rules, then you broke and screwed, period. Again as I said, I am still puzled how you can be continuited to post here. Shame of you!
You have only a sole goal here to steer the triffic to your business, that is shilling. Just look at your website, all are the Asylum post references.....
You have pointed out the inconsistet enforcement of the posting rules. Get a grip, that is the way it is; if you want the same treatment, make the same contribution.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
"Get a grip, that is the way it is; if you want the same treatment, make the same contribution."
Is this new rule here? I do not see in the Asylum rules.
here are the general posting rules:
http://www.audioasylum.com/scripts/d.pl?audio/rules.html
he consistently violated the rule B, D, and E.
here are posting rules for business owners or assoicates:
http://www.audioasylum.com/scripts/d.pl?audio/manrules.html
he consistently violated the general rule 2 as stated:
"We ask that you observe the following special rules for posting which are designed to maintain the non-commercial, hobbyist nature of the Asylum while maximizing the participation of industry members."
herein the special rules 2 - 5.
I have to agree with you. I like Allen but as you say a lot is him selling his mods. He needs to stay away from doing that. Be better if he just ran an ad here then everyone would know of him and his services.
Then he could just focus on being just one of the many people who post here and everyone would still know who he is and what he offers business wise.
PJB
Who makes a living servicing and repairing Chinese gear? So far you have gotten upset about people sharing their opinions on Chinese gear based on direct experience, yet you offer no argument that these feelings are wrong...
DanL
No, I have no intention to offer argument of these feelings are wrong or right. It is free world, you feel whateve you like.
Just like your three-word of Moniker, the last word "plate" can be a verb, though. Am I care for other's feeling towards to your Moniker name is right or wrong? I do not care.
Allen
What specific Chinese amps have you actually had experience with? This might help contextualise what currently seems to be a rather mundane blanket generalisation...
Thanks
It appears by the tone of your post you have a prejudice to Chinese Products. Are you saying all Chines products are cheap and no good. if that's the case check out some of the new products coming out of China and you may be surprised. You offered no help to the poster and I think you need to stop the prejudice stuff as that's all you contribute lately.
if that's the case check out some of the new products coming out of China
So are you basically saying he isn't prejudiced (a rather loaded term), he just hasn't updated his opinion lately since you seem to state that his opinion is based in historical fact, it's just no longer accurate?
Why don't' you do some research on Allen's post and you will he is always bashing the Chinese goods. Saying they ripped off his circuit design. It certainly sounds like he has a beef with Chinese goods. He calling their cars cheap etc. How would you characterize his statements?
Edits: 03/26/10
Accurate, in a word.If they stole his design then
he has a valid reason to hate them.
The Chinese are thieves -
that we know and it's beyond question.DanL
Edits: 03/27/10
it;s anyone's they think might be good.
Their amps today are like Korean cars of 20 years ago - pitful in terms of the driving dynamics of European cars, but good enough for average people wanting a cheap way to get to work.
I consider we build state of the art gear, in line with, say Ferrari, and I guess I get a little upset with people buying cheap stuff and then accusing good tubes as being the problem.
Regards, Allen
Hi
Just to chime in.... I guess you've never been to drag race....little "hot roddded " Hondas kicking Ferraris' butt lol
...could stay within sight of a stock Ferrari, in a drag race or somewhere where driving dynamics are important.
Hugely modified cars on a drag strip are another story.
Regards, Allen
My stock Honda was more than capable of leaving a Ferrari sucking its dust. Average acceleration to 100 kph was right on 1g. And that was 17 years ago.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
...you are not talking to a car nube here - what stock Honda 17 years ago could pull 1g in acceleration?
1g is around 9 seconds in the 1/4, and NO stock car has ever approached that.
How did you measure it, and what actual time to 60 did you achieve?
As they say, DOX or GTFO.
Regards, Allen
Not exactly a noob either...and if you'll take note I did not say 'car'...it was a CBR900RR, and it ran 10.32 at 138 with me on it. I did not say it could average 1G for a quarter, just to 100 kph. It put nearly 127 hp to its contact patch( as measured on a Dyno-Jet inertial dyno )from 893 cc.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Honda is from Japan not China
Again...sweeping generalisations and hyperbole. I ask once more, what specific Chinese made amps have you listened to? I am genuinely interested.
Post a Followup:
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
