Using Tube Integrated Amp plus Pre-Amp-Gain question??

eclein · « **on:** 15 Jan 2011, 02:49 pm »

Hey, I picked up a little Tube Integrated amp (my aim is to use it for headphones but I gotta run some JBL's with it first) thats being delivered today and I'm going to be using it with my Grant Fidelity Tube DAC/Pre-Amp and I know with Solid State gear its OK to run the Solid State Component wide open and use the Pre-amp obviously to control volume, so in this setup with an all tube amp thats integrated and a Tube Pre-amp do I just run the amp wide open or is it different with tubes???
Do I ride gain on both pieces or set one wide open and forget about it in favor of using the gain control on the other. I don't want s_it blowin up the first day, second day is OK, first day -not good!!
Thanks

bunnyma357 · « **Reply #1 on:** 15 Jan 2011, 04:32 pm »

I use a preamp before my tube integrated - I run it with the integrated volume at mid-level, and make all volume adjustments with the preamp.

I figure most things run a little ragged at the extremes, so rather than push the tubes hard by running them wide open, that the sweet spot is somewhere in the middle. Still gives me plenty of volume.

Jim C

eclein · « **Reply #2 on:** 15 Jan 2011, 04:35 pm »

Ok thanks Jim, thats what I was thinking....

Ericus Rex · « **Reply #3 on:** 15 Jan 2011, 04:40 pm »

You might get better s/n ratio by doing Jim's method. But I don't think you'd hurt anything running wide open. After all, tube amps run wide open 100% of the time.

The only other concern I can think of is overdriving the first stage of the int. amp since the incoming signal is already amplified by your pre. I don't think this would hurt anything but you could get a distorted sound.

JakeJ · « **Reply #4 on:** 15 Jan 2011, 05:01 pm »

Things to consider:

1) Is this integrated actually an integrated? In otherwords, does the integrated actually have gain before the output stage or is it like many of the less expensive amps that have one or two inputs and is actually a power amp with a switch for the inputs and a volume attenuator, i.e. passive.

2) If it does have a passive front-end and has no gain then bunnyma357's (why do I always picture a 7 foot tall man in a bunny suit wielding a .357 magnum pistol?) suggestion of running the integrated at half volume and using the volume control of the straight preamp to control level will likely result in the lowest distortion and S/N ratios.

3) If the integrated does have gain before the output stage then you will need to be careful not to overdrive the integrated with the preamp. It will be much easier to drive signal into distortion with that many gain stages plus you may not have very good volume control because it may get too loud "too fast". By this I mean your available volume control may be reduced to such a small amount of the rotation that you won't get the finite control you want.

My .02, hope it helps.

eclein · « **Reply #5 on:** 15 Jan 2011, 05:10 pm »

Its probably passive--the tube amp, based on dollar value...The pre-amp/DAC I'm using it pretty close to passive although technically it has some drive behind it..minimum amount.
The amp is only 6 watts X 2 so I'm not real worried about volume being an issue, I'll start everything at zero and work them both somewhere around 1/2 way.
Its a Musical Paradise MP-301 Integrated my friend TrungT down in the gigantic state of Texas was kind enough to sell me....while I'm waiting for Fedex to drop it off I'll dig for more info on the amp....

eclein · « **Reply #6 on:** 15 Jan 2011, 05:16 pm »

Info I just grabbed from head-fi:
_______________________________________ _______________________________________ _______________________________

REVIEW: Musical Paradise MP-301 Tube Headphone / Speaker amp
Skylab reviewed May 9, 2010 at 8:12 pm
I purchased a sample of this amp to review. Normally I don’t do that, but in this case I did, for two reasons:

1.I wanted to try a 6V6 based amp, to get a chance to try this type of tube
2.It was CHEAP! Holy poop, is it cheap - $200!

The MP-301 is actually transformer-coupled. And indeed, it had no problem driving low impedance headphones. Zero hum at all. It’s surprising enough to find an OTL amp at $200 – but a TC one? The worry here is that by necessity the transformers are cheap – and you do hear the sound of the output trannies – so the question is – at that price, can it possibly sound any good?

To find out, I bought some good tubes, to give it a fighting chance. I used Ken-Rad 6V6GT’s, and Mullard 6AU6’s (this is the driver tube type). The tube sockets are spaced too closely together to allow the use of the very sexy ST/”coke-bottle” shaped 6V6G – which is really a pity. There are plenty of 6V6GT’s to be had – including new production ones from Russia and China (which I did not try). I did try Raytheon, Tung-Sol, Sylvania, RCA, and GE 6V6GT’s and Sylvania and RCA 6AU6’s, and all of them sounded pretty good, with some differences that were easily ascribed to the specific tubes used. Tube rolling options are definitely very diverse for this amp. In addition to the 6AU6, the 6AK5 can be used as the driver tubes. However, since the 6AK5 provides more gain, which is not something I needed or wanted, I did not try any of these.

This amp is SMALL – just 9” w x 5.5” deep (not including knobs or jacks):

The amp is sold out of Canada, and according to the seller, designed in Canada, although it is Chinese made:

Note that the headphone jack is around back. This might be a PITA for some folks, but an advantage for others. In any case it is worth noting. I broke the amp in for 120 hours before reviewing. I never had any problem with noise, hum, or anything of the sort with any of the headphones I tried.

So what is amazing about this little amp, is that for $200, it sounds WONDERFUL. It is definitely an all-tube amp. It’s a tubey tube amp. If you are sick of SS and you want to spend just a little money and get a truly tubey sounding amp, this is the one. It’s lush to the point of being just slightly syrupy. It’s slightly rolled off at the frequency extremes. The bass is a little flabby on the bottom (kind of like me).

But you know what? I *always* enjoyed listening to it. A LOT. Every time I would glance over at it, I would smile. How can this thing be making this sound??? It throws a VERY wide soundstage. It BOOGIES. It grooves. It makes MUSIC. Big time. Unfailingly, and earnestly.

Is it the last word in transparency? Good lord no. Earth shattering dynamics? Nope. Treble so etched you can hear the individual hairs on the crickets in the background of the performance? Sorry, not here.
But does any of that really matter when you consider that there wasn’t a single song I played through it that didn’t get my juices flowing? And that – cripes – the thing is $200???? This amp has bedside rig written ALL OVER IT. Need a cool amp for the office, where your PC or iPod will always be your source? Here you go.

Female vocals were a delight, but don’t think the MP301 is just for small jazz ensembles (although these were great through it). Listening to “Never Enough” by Epica, both the vocals AND the driving goth-metal were so meaty I couldn’t really concentrate on anything other than the song. “Eruption > You Really Got Me” from the first Van Halen album also totally cooked through the MP301. Power Pop like “Smash” by The Murmurs propelled along at the right pace. But some music like Third Eye Blind’s “Graduate” was too thick through the MP301. The MP301’s euphonic coloration is still a coloration, after all, and it won’t work perfectly with all music.

It also doesn’t work perfectly with all headphones. It was TERRIFIC with all of my 600 ohm Beyers. It was especially great with the DT880’s. On the other hand, it wasn’t a good match with the JVC DX1000, although I highly doubt anyone will pair the two of them together. But it wasn’t a great fit with the JVC RX900, either, since they are a little thick sounding already.

I did not try the MP-301 as a speaker amp. I could never get it past 9:00 on the volume control with headphones, so I’m sure with efficient speakers it would work fine in a room of modest size. But I wouldn’t recommend it for anything more than a small speaker in an office/bedroom/dorm room type of set up. But if I were about to go off to college (oh, if only I were that young again), taking the MP-301 with me would make perfect sense given how compact it is and that it can drive speakers or headphones. Just don’t ask it to rock the whole dorm during a progressive drinking party.

A lot has been made of the tubes vs. SS dichotomy, and in general, while I have come to much prefer tubes, I think the differences are not that great. But that said, I will also say this: I have absolutely never heard a SS amp that cost $200 that was this musically enjoyable. Sorry SS lovers, but there it is. Even including the $60 or so you have to spend for good tubes, the MP-301 is about the biggest bargain in headphone audio I have heard in a while.

Admittedly, for $100 - $150 more or so there are some pretty nice amps out there. But when we’re at the lower price levels, that $100 can mean the difference between buying an amp or not for a lot of people. If you don’t have a home headphone amp today, and you have $200 to spend, I can’t possibly imagine a better way to spend it. Right now this amp is on sale for $189 – I suggest to RUN to their website and order one if you have been thinking about a cheap tube amp. Highly, enthusiastically recommended.

wilsynet · « **Reply #7 on:** 15 Jan 2011, 08:07 pm »

Quote from: eclein on 15 Jan 2011, 05:16 pm

The MP-301 is actually transformer-coupled. And indeed, it had no problem driving low impedance headphones. Zero hum at all. It’s surprising enough to find an OTL amp at $200 – but a TC one?

It would indeed be very surprising as it does not seem possible to be both output transformerless (OTL) and transformer coupled at the same time.

eclein · « **Reply #8 on:** 15 Jan 2011, 08:40 pm »

Good point!!! I just copied the info as I noted in the beginning, it was taken directly froma Head-fi user review...

JakeJ · « **Reply #9 on:** 15 Jan 2011, 09:12 pm »

Transformer coupled could mean there is an interstage transformer between then input stage and the output stage. Or the input itself could be transformer coupled to the 6AU6s. Found the Canadian website but this amp is not listed so I could find no further info.

You could pop the bottom cover off and snap a couple of photos to post in this thread and we might be able to see what the circuit topology is. If you are interested. Obviously it satisfies the boogie factor and that's what matters.

eclein · « **Reply #10 on:** 15 Jan 2011, 09:26 pm »

6 watts gets loud, plenty loud....JakeJ I appreciate your time but I'm not sweating it, it is what it is, sounds good and thats all I care about. Its supposed to be a my new/old headphone amp but I had to hook it up to some JBL's...it works, sounds great...Thanks TrungT!!!!!

Rolled in the JJ's before I even hooked it up...LOL....Good stuff, now I just have to figure out hooking up my sub...I should be able to take the SS output from the DAC/Pre and use it but for some reason the sound gets mucked up..will think while I listen....

eclein · « **Reply #11 on:** 15 Jan 2011, 09:28 pm »

Even Ray Lewis digs it.....

JakeJ · « **Reply #12 on:** 15 Jan 2011, 09:59 pm »

Thanks for the photo. Now I see it does have output trannies thus it is not an OTL amp. All cleared up for me, thanks!

bunnyma357 · « **Reply #13 on:** 15 Jan 2011, 10:04 pm »

Quote from: JakeJ on 15 Jan 2011, 09:59 pm

Thanks for the photo. Now I see it does have output trannies thus it is not an OTL amp. All cleared up for me, thanks!

Is it possible the Headphones out are a different path and are OTL?

The Head-Fi review was clearly talking about using it as a head-amp.

Jim C

JakeJ · « **Reply #14 on:** 15 Jan 2011, 10:13 pm »

Yup, most definitely a possibility. Say, eclein, do the speaker outputs turn off when a set of cans are plugged in?

eclein · « **Reply #15 on:** 15 Jan 2011, 10:23 pm »

How do you guys know this stuff??? Hey there is a diagram on top of the two stacks on the right...a pic would help, I'll get one.
Some questions...
1) Integrating the Sub: the Virtue TWO.2 has a sub out so I never had to worry to much about this, I hooked up the powered sub to a SS output from the DAC/Pre-amp and the new/old amp is using the tube outputs L & R....so I'm controlling the volume to all speakers there when raising the DAC/Pre-amp gain correct?
So when raising the gain on the amp itself I'm just raising the gain on the mains??
2) How does a sub sound when out of phase?? Like a transistor radio???
3) I got tweaking to do, but this is fun, the sub is the tricky part because I'm raising gain in two places but only effecting the sub in one.
My friend Trung said the amp was probably not even broken in yet so its fresh, fresh ...enjoying this, I'm totally shocked it has so much volume, I can't open both pots 1/2 way-too loud.
I'll take pics of top schematic for those inquiring minds then I'll ask you guys about tubes, this has two different sizes and I'm used to one-5670 in the DAC.

YES... cans stop signal to speakers

eclein · « **Reply #16 on:** 15 Jan 2011, 10:32 pm »

eclein · « **Reply #17 on:** 16 Jan 2011, 01:06 am »

Good game....OK...so this baby takes two sizes of tubes....I need some edu-macation on these tubes... the bigger ones are power tubes?? I'm guessing totally but give me a shot here. The others are something to do with the integrated/pre function???
Which ones can kill me?
Which ones have largest effect when rolling....there were two JJ brand tubes Trung sent along with the stock tubes and they are in now...sounds most excellent so I'm in no rush to start rollling and my budget is zip but the tunes sound great and thats all that matters.
Any tips? Pointers? Links?
TY

JakeJ · « **Reply #18 on:** 16 Jan 2011, 05:53 am »

Yes, the big tubes are your 6V6 output tubes and the small ones with the spring-loaded covers are the 6AU6s. Most likely the biggest bang for your buck will be to roll the small driver tubes (6AU6 European equivalent is the EF94). You should be able to find lots of these in NOS (New Old Stock) all over the net. Peruse the Tube Vendor thread in this circle for a good list of the best vendors and have fun!

eclein · « **Reply #19 on:** 16 Jan 2011, 11:48 am »

Thanks JakeJ!!! I fell asleep with headphones on last night and strictly as a headphone amp, which is really why I got it, the sound is nice and full, very dynamic. I'm really, really surprised by how nice this little bugger sounds. The 6 watts it touts are more than enough power- another surprise- for my current room and speaker choice. I gave it 2 hours to settle in to it's new home and then started playing all my referece CDs and I tried to find something, anything to bitch about but all I could do was tap my foot and shake my head with the music.
Plans are made to be broken and this plan just got rethunk!!!
I hooked it up to speakers for kicks and it kicked back with nice full bodied tone, tight bass, crystal clarity- I got some re-arranging to do, in a good way.