The 'NEW' YAQIN MS-20L Integrated Vacuum Tube Amp Thread - Page 13 - AVS Forum
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post #361 of 838 Old 02-15-2012, 01:47 AM
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here is a used 34d for $400 on audiogon but it is only 40 watts.
http://app.audiogon.com/listings/yaq...or-sale-ms-34d
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post #362 of 838 Old 02-15-2012, 12:24 PM
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well i picked up a used ms-20l, should be here next week

going to try with zu essence & tekton m-lore's, peachtree audio DAC
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post #363 of 838 Old 02-16-2012, 12:27 PM
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Hi all,

Like many, I've been following this thread for sometime as I researched amps from Yaqin, Mingda, Dared etc...also comparing el34 to kt88 to 300b.....I'm pretty much researched out! I'm hoping for some clarification regarding some members here that have been using the MS-12B tube preamp between their cd/dvd and the MS-20l. Since the MS-20l already has a preamp, why the need for the added pre and what do you gain by it?
My search has lead me to either the MS-20l or the MS-300c. The amp will be paired with Tekton Lores. As I'm looking for a detailed, open soundstage, I'm not sure which amp will provide this. Also, I'm not sure if the low output(9.5w) of the MS-300c will be a good match with the Lores. Looks like.....more research!

Thanks and look forward to contributing to the forum.
Regards,
Scott
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post #364 of 838 Old 02-16-2012, 01:56 PM
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I was considering the 300C as well, but opted for the 20L as the price of replacement 300B tubes was the deal breaker for me. Your Lores are pretty efficient so the 300C's 9.5W should give you ~ 107-108dB...which is plenty loud, for my taste anyway.
The 20L is running el34b's(pentodes) in push-pull. I wouldn't describe the sound as "tube-like"...it's almost SS in nature, with very detailed mids/highs. There is a switch that lets you run the El34's as "strapped triodes", but it's pointless really. You are losing half the output power for a reduction in distortion that you can't realize because the output transformers are designed for the ultra-linear circuit and have too low an anode-to-anode resistance to take full advantage of the lower distortion of the triode-strapped El34's. How's that for a run-on sentence?
The 300C is a single-ended triode amp. SET's done right have astonishing detail, especially at lower listening levels (compared to other amps). I've never personally heard a 300C, so i can't give you much info about it. One thing to keep in mind about SET amps is that they don't usually pair well with speakers that have wonky impedance curves and complex crossover networks.
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post #365 of 838 Old 02-16-2012, 04:48 PM
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Rntlee,

Thanks for the response. Yeah, the Lores use a full range transducer along with a tweeter for a very specific frequency range. That is the only crossover. The Lores are supposed to be quite efficient so I guess the 300b setup would work. I have another week or so before I make the decision. It'll be a tough call.
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post #366 of 838 Old 02-16-2012, 06:59 PM
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Hi all,

First all after months of TUBE AMP curiosity and this thread made me take a plunge on tube amp.

I bought a Yaqin MS-34 D to put my feet on the tube world....

This is my setup

PC-> Peachtree decco 2(tube preamp) -> Yaqin MS-34d ->Vienna acoustics Haydn grand (4 Ohm 89db and recomended amp 25-180W)

my question is that this amp is enough to drive my Haydn grand? (i listen it nearfield right on face kinda no need for high voice) also what kinda tube i should be rolling...

it is still a week i will get the amp...hope this bring a good return to investment...


V
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post #367 of 838 Old 02-17-2012, 07:01 AM
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Your setup should work well, imo.
A lot of people dis the Chinese valves, but they're actually not that bad. I'm still using the original el34b's but have some Tung Sol's on order as back-ups. A great sub for the 6J1's are these Russian tubes. They're reasonably priced and an excellent tube for the input stage and phase splitter of your amp.
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post #368 of 838 Old 02-17-2012, 09:41 AM
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Quote:
Originally Posted by rntlee View Post

Your setup should work well, imo.
A lot of people dis the Chinese valves, but they're actually not that bad. I'm still using the original el34b's but have some Tung Sol's on order as back-ups. A great sub for the 6J1's are these Russian tubes. They're reasonably priced and an excellent tube for the input stage and phase splitter of your amp.

thanks actually i am talking to the seller for last couple of months...seems to be a great guy has helped me a lot in the tube section
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post #369 of 838 Old 02-20-2012, 09:25 PM
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Quote:
Originally Posted by indianguyinny24 View Post

Hi all,

First all after months of TUBE AMP curiosity and this thread made me take a plunge on tube amp.

I bought a Yaqin MS-34 D to put my feet on the tube world....

This is my setup

PC-> Peachtree decco 2(tube preamp) -> Yaqin MS-34d ->Vienna acoustics Haydn grand (4 Ohm 89db and recomended amp 25-180W)

my question is that this amp is enough to drive my Haydn grand? (i listen it nearfield right on face kinda no need for high voice) also what kinda tube i should be rolling...

it is still a week i will get the amp...hope this bring a good return to investment...


V


I want to add Subwoofer in this configuration can some one help....as my VA goes only till 45hz...and i do listen some missed beats...
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post #370 of 838 Old 02-21-2012, 02:55 PM
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Easiest way is to find a sub with high-level inputs and outputs. That's what i did, works super.
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post #371 of 838 Old 02-21-2012, 06:24 PM
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Quote:
Originally Posted by rntlee View Post

Easiest way is to find a sub with high-level inputs and outputs. That's what i did, works super.

getting a good deal for NHT subone for around 150$.....that should help to drive the lows..

V
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post #372 of 838 Old 02-22-2012, 01:07 AM
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people who use a separate preamp, do you leave the vol. on 100% on the ms-20l? just wondering if its safe to do so..
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post #373 of 838 Old 02-22-2012, 07:22 AM
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It'll depend on the output voltage from your preamp. You don't want the + peaks of the signal into the first stage of the Yaqin to exceed the bias voltage on the grids of the 6J1's. That would cause a grid current to flow, supplied by the signal, which will cause the positive peaks to be distorted before they're amplified. The MS-20L is probably designed with an input signal of ~2V in mind.
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post #374 of 838 Old 02-22-2012, 10:50 AM
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hmm, here's what i can find about the peachtree's preamp:

Class A Preamp output stage
<30 Ohms output impedance
Hybrid tube design using triode (Stereo 6N1P)
6.5V output @ 2.0V input

2V input so should be ideal?

one other thing, i notice a slight high pitched whining from time to time... normal?

anyway, heres a pic of my newly acquired ms-20l, powering zu essence, sounds great so far, well worth the price i paid


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post #375 of 838 Old 02-22-2012, 11:35 AM
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I think 6v from the Peachtree at full output would be to high an input voltage for the Yaqin. It might be the source of the whine you hear...it may be causing the Yaqin to oscillate...

The high pitched whine is definitely not normal, the amp should be dead quiet. When do you hear it? Is it coming through the speakers or from a tube? Both channels?
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post #376 of 838 Old 02-22-2012, 11:47 AM
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Quote:
Originally Posted by rntlee View Post

I think 6v from the Peachtree at full output would be to high an input voltage for the Yaqin. It might be the source of the whine you hear...it may be causing the Yaqin to oscillate...

The high pitched whine is definitely not normal, the amp should be dead quiet. When do you hear it? Is it coming through the speakers or from a tube? Both channels?

it still whines when im using the line-out from the peachtree.. just trying the pre-out to see the difference

seems to be intermittent, not from the tubes, pretty sure it's coming through one channel, it goes away when i turn the source off (optical) with the dac/amp still running, it's pretty faint but still noticeable at low volumes
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post #377 of 838 Old 02-22-2012, 12:53 PM
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Quote:
Originally Posted by koven View Post

hmm, here's what i can find about the peachtree's preamp:

Class A Preamp output stage
<30 Ohms output impedance
Hybrid tube design using triode (Stereo 6N1P)
6.5V output @ 2.0V input

2V input so should be ideal?

one other thing, i notice a slight high pitched whining from time to time... normal?

anyway, heres a pic of my newly acquired ms-20l, powering zu essence, sounds great so far, well worth the price i paid



Thanks ...

this is kinda exactly my setup

PC -> Peachtree decco2 ->Yaqin Ms-34d -> VA haydn....

hope you are enjoying the sound..

V
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post #378 of 838 Old 02-23-2012, 07:25 AM
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Quote:
Originally Posted by koven View Post

hmm, here's what i can find about the peachtree's preamp:

Class A Preamp output stage
<30 Ohms output impedance
Hybrid tube design using triode (Stereo 6N1P)
6.5V output @ 2.0V input

2V input so should be ideal?

one other thing, i notice a slight high pitched whining from time to time... normal?

anyway, heres a pic of my newly acquired ms-20l, powering zu essence, sounds great so far, well worth the price i paid

Yaqin needs between 0.5 and 1.0 volts to reach full power, when volume setting is all way up. If your preamp sends more, you have turn volume down. There is usually a balance between preamp and power amp volume settings. Try to set power amp volume so that turning preamp on and off does not significantly change residual noise level in speakers.
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post #379 of 838 Old 02-23-2012, 10:16 AM
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Looked up the sensitivity of the ms-20l and it's actually 0.25v, which is pretty darn high. You source needs only 0.25v for the amp to produce full rated power at full gain.
Most cd players etc. have a line level output ~2v. That's probably the reason so many complain about the ms-20l volume control with the remote. It makes the volume dial that much more touchy with a higher than 0.25v source.
I'd adjust the volume on the peachtree to a level that makes the volume control on the Yaqin not overly sensitive to adjust with the remote control.
Also, having the preamp output too high is going to make the Yaqin clip at a much lower setting on the dial than would normally occur...you could place your speakers in danger unawares because the Yaqin volume dial has now become artificially sensitive.
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post #380 of 838 Old 02-23-2012, 12:29 PM
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Still building my system. I like to keep it simple though.

MC34-AB. I picked up shuguang 12at7-t and cv181-t tubes that I will put in tonight. The t-series el34 tubes are pretty expensive so they will have to wait.


In the mean time I need some proper speakers. Going to start work on one of the designs on the frugal horn website. Thankfully my father inlaw is pretty good at wood working so it should actually work.


I did have one question for you guys. I wanted to pick up a power filter/conditioner, or whatever you call it. The system is incredibly quiet but why not try and improve on that and protect my investment at the same time.

I also picked up a bunch of those tarted up power cables. Not sure they do anything but what the hell they look cool.
LL

tubes tubes and more tubes.
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post #381 of 838 Old 02-23-2012, 02:27 PM
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Unless you have sketchy power delivery like frequent brownouts of whatever duration or line noise, I would keep it simple and less expensive. I've been using a Belkin PureAV PF30 which I got bundled free with my first Plasma back in '05 and it has never let me down. Used to get frequent micro-brownouts and everything in the system just shut down clean with no popping or strain. Thankfully, the line is much better now and my system is very quiet with all equipment averaging about 105dB S/N.
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post #382 of 838 Old 02-24-2012, 10:00 AM
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i just got yaqin ms-34d still listening....still making opinion....


just had one question what is difference between these two modes...

Ultra Linear and Triode Mode....

Thanks
V
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post #383 of 838 Old 02-24-2012, 11:17 AM
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"Ultra-linear mode" means that the screen grids of the output tubes (the EL34b's) are connected to taps on the primary of the output transformer. This mode of connection has almost as much power as connecting them in "tetrode" mode (screen grid connected to the power supply), but with much lower distortion.

"Triode mode" means that the each tubes screen grids have been connected to the anodes of their tube . This lowers distortion further, but sacrifices power output by about 50-60%.

You won't hear much difference, besides lower output, between modes on this amp as the output transformers are designed with Ultra-linear connection in mind and so have an anode-to-anode resistance of probably around 6k ohms. To take full advantage of the lower distortion of Triode connection, the output transformers should have an anode-to-anode resistance of around 9k-10k ohms.
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post #384 of 838 Old 02-24-2012, 11:49 AM
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mine is plugged directly into a wall outlet... works for me...

- chris

 

my build thread - updated 8-20-12 - new seating installed and projector isolation solution

 

http://www.avsforum.com/t/1332917/ccotenj-finally-gets-a-projector

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post #385 of 838 Old 02-24-2012, 12:18 PM
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Quote:
Originally Posted by ClarkeBar View Post

Unless you have sketchy power delivery like frequent brownouts of whatever duration or line noise, I would keep it simple and less expensive. I've been using a Belkin PureAV PF30 which I got bundled free with my first Plasma back in '05 and it has never let me down. Used to get frequent micro-brownouts and everything in the system just shut down clean with no popping or strain. Thankfully, the line is much better now and my system is very quiet with all equipment averaging about 105dB S/N.


Thanks I have looked at the belkin unit also. I was thinking about going with the xindak xf-1000s. Supposed to have really good build quality and kinda matches what I am going for. Stupid reason but what the hell.

the only time I really notice an issue with the power in my place is when my heater kicks on. That comes right thru the speakers.

tubes tubes and more tubes.
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post #386 of 838 Old 02-25-2012, 08:11 AM
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Quote:
Originally Posted by rntlee View Post

"Ultra-linear mode" means that the screen grids of the output tubes (the EL34b's) are connected to taps on the primary of the output transformer. This mode of connection has almost as much power as connecting them in "tetrode" mode (screen grid connected to the power supply), but with much lower distortion.

"Triode mode" means that the each tubes screen grids have been connected to the anodes of their tube . This lowers distortion further, but sacrifices power output by about 50-60%.

You won't hear much difference, besides lower output, between modes on this amp as the output transformers are designed with Ultra-linear connection in mind and so have an anode-to-anode resistance of probably around 6k ohms. To take full advantage of the lower distortion of Triode connection, the output transformers should have an anode-to-anode resistance of around 9k-10k ohms.

Could the anode-anode resistance be altered without changing the transformers?

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post #387 of 838 Old 02-25-2012, 03:37 PM
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Originally Posted by cytowing View Post

Could the anode-anode resistance be altered without changing the transformers?

Not without rewinding them.

I'm not sure that running the amp with triode-strapped pentodes is really going to net a huge sonic improvement anyway. Here's a chart from Mullard:



The "Distributed Load" is ultra-linear connection. You can see that compared with triode connection there is not much improvement in distortion to be had.

Changing the coupling caps to a higher quality capacitor (like Auricaps, maybe) would probably yield bigger sonic improvement.
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post #388 of 838 Old 02-25-2012, 06:45 PM
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Quote:
Originally Posted by rntlee View Post


Not without rewinding them.

I'm not sure that running the amp with triode-strapped pentodes is really going to net a huge sonic improvement anyway. Here's a chart from Mullard:

The "Distributed Load" is ultra-linear connection. You can see that compared with triode connection there is not much improvement in distortion to be had.

Changing the coupling caps to a higher quality capacitor (like Auricaps, maybe) would probably yield bigger sonic improvement.

Lets explore that further, as its a simple mod

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post #389 of 838 Old 02-26-2012, 06:03 AM
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Quote:
Originally Posted by rntlee View Post

Not without rewinding them.

I'm not sure that running the amp with triode-strapped pentodes is really going to net a huge sonic improvement anyway. Here's a chart from Mullard:



The "Distributed Load" is ultra-linear connection. You can see that compared with triode connection there is not much improvement in distortion to be had.

Changing the coupling caps to a higher quality capacitor (like Auricaps, maybe) would probably yield bigger sonic improvement.

Thanks for the post, very interesting. I had though about re-capping the amp but thought I would wait and I don't have a schematic yet either.

This got me to thinking that maybe we should have a list of mods for the MS20L.

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post #390 of 838 Old 02-26-2012, 06:23 PM
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The only schematic of this amp I'm aware of is this one(I got it from Song @ Canadian Hifi Online):

Attachment 238521

It's possible there are errors, I haven't had my amp open yet to check.

My only concern with posting/encouraging internal modifications is the danger to inexperienced modders. Tube amps utilize very high (ie. deadly) voltages. There's 450V at hand inside the MS-20L that will give anyone who comes into contact with it a very bad day.

That said, one modification I did need to do with mine was to place a bucking transformer between the amp and the mains voltage. I'm in Canada and my measured household voltage is 126-127VAC. This is a little high for this amp, which seems to be designed for a voltage of around 115VAC. The heaters on the tubes are to be run at 6.3v for maximum tube life. Mine were at about 6.9v, which would have shortened the tube life by about half:
Attachment 238526
I bought a boost/buck transformer from ebay and it drops my 126VAC to 115VAC. This amp also uses a SRPP for the input stage, which is pushing the heater to cathode voltage in the top 6J1 to the max allowable. I may have even been exceeding it with my high mains voltage.
LL
LL
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