Musical Paradise MP 701 Mark II Owners & Discussion Thread

[MrBurns84]

Shame about your preamp experience @sthaus.  Im my experience the EH 6H30Pi are nice on this preamp and a good starting point.  As you pointed out with the caps, the values used and the type of cap used makes a difference and therefore hard to say what sounds best to you - very subjective.  I kept my bypasses just a tad under 10uf each bank (i have the mk2) and this sounds the best to me.  

[sthaus]

5 hours ago, MrBurns84 said:

Shame about your preamp experience @sthaus.  Im my experience the EH 6H30Pi are nice on this preamp and a good starting point.  As you pointed out with the caps, the values used and the type of cap used makes a difference and therefore hard to say what sounds best to you - very subjective.  I kept my bypasses just a tad under 10uf each bank (i have the mk2) and this sounds the best to me.  

Agreed, it is very subjective to talk about sound. I have no experience on this pre-amp. Do you have better recommendations than 6H30pi ? Many thanks 

[kbollox]

On 14/06/2024 at 8:41 AM, sthaus said:

Agreed, it is very subjective to talk about sound. I have no experience on this pre-amp. Do you have better recommendations than 6H30pi ? Many thanks 

 

I'm running 6N23Ps and think they sound wonderful. Might be an alternative for you to try out.

 

I've heard to avoid the 6N23P-ev aka military issue version: see link

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1627956584/0

 

Edited June 15, 2024 by kbollox

[muon*]

2 hours ago, kbollox said:

 

I'm running 6N23Ps and think they sound wonderful. Might be an alternative for you to try out.

 

I've heard to avoid the 6N23P-ev aka military issue version: see link

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1627956584/0

 

Correct, the 6N23P is a drop in replacement for the 6922, the 6N23P-ev is not and will not be suitable in some circuits.

 

I liked the 75-76's variants of the Voskhod 6N23P with the single post getter in other kit, I don't have the MP.

Edited June 15, 2024 by muon*
typo

[MrBurns84]

On 14/06/2024 at 10:41 PM, sthaus said:

Agreed, it is very subjective to talk about sound. I have no experience on this pre-amp. Do you have better recommendations than 6H30pi ? Many thanks 

I'll PM you 

[the-chauffeur]

Hello gang - hope you don't mind another voice in the thread.

 

Just opened up my Mk3 - both in unboxing terms and pulling bits of it apart.  Gained a lot of insight from this thread into valve/cap options; I'm running the bog standard bits right now to set myself a baseline.  I'm also a keen tinkerer(?) and like to get into the guts of this stuff.  Yeah, I know - warrantee be damned; one of the reasons I chose the Mk3 was because it looks like I can pretty much fix anything on it, even if I am a bit ham-fisted when it comes to soldering.  A couple of things I've learned already that I don't think have been mentioned before:

 

On/off switch - out of the box, mine was easy enough to push in/latch on, but it really struggled to turn off/release, to the point where I had to physically pull it out.  Very simple fix - remove the volume/selector knobs and loosen the front panel.  The tolerances around the switch button are quite tight and if the front plate has shifted very slightly in transit, it'll drag on the switch sides.  Again, very, very simple - give the front panel a wiggle and tighten the screws when the button works as you'd expect.

IEC socket - get the back plate off the amp and you'll see the socket is very basic and there's not much to it; it's got a smoothing capacitor on it, but that's about it.  You'll also see a lot of empty space in the transformer cavity.  I've swapped the standard IEC socket for an EMI blocker - fits the exact same cutout in the backplate and other than the fuse cover, you'd never know it was there.  It took a bit of rewiring of the small power distribution board that was attached to the back of the standard socket, but nothing particularly complicated.  No pictures 'cos it was proof of concept and the soldering is awful; at some point I'll go back to it and do a proper job on it.  Suffice to say that it easily fits inside and has the added bonus of allowing me to attach the voltage switch directly to the back panel (as standard it stands about half an inch off the back panel).

 

Additional work I'd like to take a look at doing includes working out what the power source is for the tube heater circuits and if it's the main transformer, maybe add a separate one to deal with power for stuff that's not in the audio path.  My goal is to isolate anything that's not signal related in the hope it'll reduce any interference or other noise.  I'll also be adding trying sound isolation materials in the transformer cavity (Deadmat or similar) to try to dampen the mains hum.  In addition, I want to look at what it might take to 'balance' the unbalanced XLR sockets.  

Anyways, that's enough for now.  Waiting on a couple of rectifier tubes to show up (yeah, I know I that's not exactly baselining . . . ).  Cheers.

Edited June 21, 2024 by the-chauffeur

[sthaus]

Is there anyone try/experience 274b like Psvane Acme 274b or Sophia Aqua II 274b for the rectifier ? 

[MrBurns84]

I have a 20H choke in the mail to upgrade the old choke on my Mk2 model, lets see what this brings - supposedly lower noisefloor  .  @the-chauffeur the transformer hum is an issue and it buzzes more than the MP dac that i have.  I'll be watching closely your thoughts on dampening this.  Shame though that this Mk3 model didnt incorporate a dc blocker like the newer mp-dx dac does as there is ample space for this underneath near the torroid.  Lost opportunity me thinks. 

 

[Vintage_Hi_Fi]

4 hours ago, sthaus said:

Is there anyone try/experience 274b like Psvane Acme 274b or Sophia Aqua II 274b for the rectifier ? 

I have a psvane 274b rectifier tube it’s very good, great dynamics and compared with a mellow 5u4gb

[Baci]

1 hour ago, Vintage_Hi_Fi said:

I have a psvane 274b rectifier tube it’s very good, great dynamics and compared with a mellow 5u4gb

 

Interesting - where did you purchase it from? Is there a psvane vendor in AUS you could recommend?

[Vintage_Hi_Fi]

11 minutes ago, Baci said:

 

Interesting - where did you purchase it from? Is there a psvane vendor in AUS you could recommend?

I don’t know where it was bought from I got it with the musical paradise pre amp when I bought it here’s a photo of the box I have a nos Siemens gz 34 and Philips nos 5u4gb the psvane 274b is the pick of the bunch as a reference 

[sthaus]

AliExpress is the way to get them here ! Make sure you have someone at home or delivery them to your free Auspost Parcel Locker.  I lost my item once from FH Express since they left my item outside the building of my workplace at “7:16 am” (public expose) !! Seriously .. those guys are not Australian and never get an office job in Australia before, otherwise they wouldn’t do that way  

 

 

 

[RockRolley]

42 minutes ago, Baci said:

Is there a psvane vendor in AUS you could recommend?

I think Mark @SonicArt can supply  Psvane. I’ve bought some from him before. Awesome to deal with, highly recommended 

[the-chauffeur]

@MrBurns84 You're right about the transformer - noisier than I'd like but far from the worst I've encountered.  Took the bottom section apart earlier, pulled up the transformer and choke and applied Deadmat/Killmat to the top, bottom and front end of the enclosure.  Back together, the noise is still there but it's quieter.  Benefits so far don't seem huge and may not be of any value who doesn't have their amp within a couple of feet of their seating position.  Right now, mine's on my desk, so I'm very aware of the sound the unit makes without any signal.

 

Not sure if your board is the same but poking around with a multi-meter while the circuit board was up, I found one of the choke wires goes to the heater circuit on the rectifier tube socket.  Oddly I couldn't find feeds for what I assume is the heater pin on the other 3 tube sockets (pin 1) but TBH today's job was the sound deadening, so I wasn't looking too hard.  That said, pulling the board up is really very simple, so when I've got more time I'll have another go with the 'meter. 

 

Noticed what I'd describe as a low-level sizzle from the speakers which I assume is from the valves.  So I've added a 20H choke to my shopping list because why not - will be interesting to hear your thoughts when yours is in.

 

You're right about the EFI/DC blocker - would've been nice but my guess is that it's down to manufacturing simplicity.  MP almost certainly have a stack of the mini power boards I mentioned to work through before considering revising that area.  At the same time, the IEC socket I used was about twice as deep as the standard.  Much as I'm sure they'd be open to the idea from a final product quality standpoint, it would require a very different assembly process that would likely  increase base cost.  Fortunately not a particularly complicated bit to change out. 

 

 

Edited June 22, 2024 by the-chauffeur

[Mihai]

5 hours ago, MrBurns84 said:

I have a 20H choke in the mail to upgrade the old choke on my Mk2 model, lets see what this brings - supposedly lower noisefloor  .  @the-chauffeur the transformer hum is an issue and it buzzes more than the MP dac that i have.  I'll be watching closely your thoughts on dampening this.  Shame though that this Mk3 model didnt incorporate a dc blocker like the newer mp-dx dac does as there is ample space for this underneath near the torroid.  Lost opportunity me thinks. 

 

I'm also interested about choke upgrade in Mk2. Please share with us your findings.

The noise of the power supply inside my preamp is variable, sometimes is dead silent and I think is due to DC on my power line. I'll try a DC blocker first to check if the noise will vanish.

[MrBurns84]

50 minutes ago, the-chauffeur said:

@MrBurns84 You're right about the transformer - noisier than I'd like but far from the worst I've encountered.  Took the bottom section apart earlier, pulled up the transformer and choke and applied Deadmat/Killmat to the top, bottom and front end of the enclosure.  Back together, the noise is still there but it's quieter.  Benefits so far don't seem huge and may not be of any value who doesn't have their amp within a couple of feet of their seating position.  Right now, mine's on my desk, so I'm very aware of the sound the unit makes without any signal.

 

Not sure if your board is the same but poking around with a multi-meter while the circuit board was up, I found one of the choke wires goes to the heater circuit on the rectifier tube socket.  Oddly I couldn't find feeds for what I assume is the heater pin on the other 3 tube sockets (pin 1) but TBH today's job was the sound deadening, so I wasn't looking too hard.  That said, pulling the board up is really very simple, so when I've got more time I'll have another go with the 'meter. 

 

Noticed what I'd describe as a low-level sizzle from the speakers which I assume is from the valves.  So I've added a 20H choke to my shopping list because why not - will be interesting to hear your thoughts when yours is in.

 

You're right about the EFI/DC blocker - would've been nice but my guess is that it's down to manufacturing simplicity.  MP almost certainly have a stack of the mini power boards I mentioned to work through before considering revising that area.  At the same time, the IEC socket I used was about twice as deep as the standard.  Much as I'm sure they'd be open to the idea from a final product quality standpoint, it would require a very different assembly process that would likely  increase base cost.  Fortunately not a particularly complicated bit to change out. 

 

 

Thanks for this @the-chauffeur.  Mine's the older mk2 board with the choke on the topside.  A while back a few year ago on audio circle forum i had a conversation with a guy in Canada that did mod's across the mk preamp and dac and he said to me he swapped out the stock power filter caps to low esr mundoft lytics and noticed a good change to the sound.  He also swapped out some of the Dale resistors with AMRG's and Audio Note Tantalums along the driver tube circuit paths and noticed another level of improvement in clarity.

 

I dont notice the transformer buzz from my seating location as i'm quite a few meters away from the pre.  I do have some of that sizzling noise when my ear is against up close to the tweeter of my speakers.  I hope the upgraded choke will dampen this down much more.  

 

[MrBurns84]

3 hours ago, Vintage_Hi_Fi said:

I have a psvane 274b rectifier tube it’s very good, great dynamics and compared with a mellow 5u4gb

The psvane 274b is quite a nice airy rectifier. agreed good dynamics with this one, but a tad lighter on the bass.

The linlai 274b WE replica is as airy and spacious but a little bit warmer on the tone and the mids a bit more forward.

[the-chauffeur]

If you fancy having a go at switching the standard control knobs for the black versions shown on this page, there's a couple of things worth knowing.

 

Source dial - the pot uses a split shaft (like this one) that gets clamped from both sides by two grub screws when the silver knob is mounted.  Undo both grub screws and the knob will come off easily.  The replacement knob is about the right depth to accept the shaft, so it's pretty much a case of replacing one with the other.  I put mine so when the pot is set on source 2, the arrow points to top dead centre but YMMV.

 

Volume dial - the pot uses a solid shaft (like this one) with one flat face that gets clamped with one of the two grub screws for correct alignment.  The shaft is around 3mm longer than the source knob, which means the mating hole in the black replacement isn't deep enough and left as is, will sit off of the face of the amp.  Not a big issue, and if you don't want to get the tools out, you can loosen the source knob and resite it the same distance from the faceplate so they match.

 

If you want to get the volume knob to sit closer to the faceplate, there's a few things you can do that involve progressively more tools:

 

FULL DISCLOSURE - I've done several mods including the following and right now, I can't make the volume increase/decrease using the remote (it works fine manually).  Nothing's damaged so I'm pretty sure it's both not this mod that's the problem and something really simple, but will leave this warning here until I find the root cause/solution.

 

Add a washer behind the faceplate - with the knob removed, get a pair of long-nosed pliers and undo the nut that secures the pot to the faceplate.  Pull the board the pot is mounted to backwards and remove the shaft from the hole in the faceplate.  Now find a washer that'll fit round the shaft - inner diameter of about 8mm - and put it on.  You may need to file a flat spot on the outer edge of the washer 'cos the pot has a locating pin that you need to avoid.  Mount everything back to the faceplate and with luck there'll be just enough thread protruding to tighten the nut that holds the shaft/pot in place.  That'll reduce the distance between the back of the knob and the faceplate by about 1mm.

 

Trim the length of the volume pot shaft - this will ultimately be the way to get the best fit, but it's also the most work.  Start by removing the board the pot is mounted to from the faceplate and take it out of the case.  There are two issues you'll need to deal with - the overall length of the shaft and the length of the flat area on the shaft.  The former is very straightforward if you've got a Dremel, or for the more adventurous, an angle/bench grinder.  You'll need to shorten the shaft by about 3mm but try a bit at a time until it's the right length for your application.   This will be enough to get the knob to sit almost flat on the faceplate. 

Extend the flat face on the shaft - once I'd shortened the shaft, I found the grub screw didn't get enough purchase on the remaining length because the flat section didn't extend far back enough.  If you have the same issue, you'll need to extend the flat face along the remaining shoulder length of the shaft.  Again, take a Dremel or similar and using the flat face as a reference, make a flat spot on the remaining shaft shoulder for the grub screw to lock onto.  Sounds more complicated than it is; just go easy, do a bit at a time and keep checking your work.

 

 Looks nice when done and no wobble/wiggle.

Edited June 23, 2024 by the-chauffeur
Added warning in relation to IR

[the-chauffeur]

Hum - spent a fruitless day chasing down the hum I mentioned above.  It was accompanied by a pronounced sizzle and for a while I just assumed they all do that but if I looked very, very hard and tested all sorts of thing, I'd be able to find/fix the cause.  Long story short, it was ground loop hum which was exacerbating the 'natural' tube noises.  Utterly baffled me because I've been using a different amp in the exact same chain and never had any issues - everything's plugged into the same socket and runs through a power conditioner.  Shouldn't have assumed that it was either the amp or downstream that was the problem.

 

Choke - fitted one of these as a cheap chassis noise reduction measure.  Had to put it on its side to get it in the case, but that's hardly a tricky job.  Does it make any difference?  Maybe - who knows.  Certainly doesn't sound any worse, but my ability to do accurate A-B testing tends to fall apart if I have to do something technical (like replace a choke) between auditions.  I'm also in the fortunate position that I've got a lot of acoustic treatment and DSP of sorts in the room, and the power amps are very, very easy to drive which all makes even the most budget pre-amps sound decent.  I'm keeping the original choke so if I get very bored at some point in future I might do a side-by-side. 

 

Capacitors - switched out the outputs for a couple of these.   Still working out the best way to discharge the originals . . . 

 

Valves - picked up a couple of moderately priced regulator valves - RCA 5R4G and Svetlana 5U4G.

 

I'm justifying all this to myself as having bits to contrast/compare.

Edited June 25, 2024 by the-chauffeur

[the-chauffeur]

Post no longer required but can't seem to delete it.  Found the answers elsewhere (the user manual - who knew . . .).

 

And a couple of questions for anyone with the DAC:

 

- did you add the Raspberry Pi option; 

- if you did, does it come prebuilt or do you build it yourself; and

- was it worth it for you?

 

I'm spec-ing out a DAC and this is about the only option I don't have a good answer to.  Right now, I don't use any streaming services but might want to at some point in the future.

Edited June 26, 2024 by the-chauffeur

[MrBurns84]

5 hours ago, the-chauffeur said:

Hum - spent a fruitless day chasing down the hum I mentioned above.  It was accompanied by a pronounced sizzle and for a while I just assumed they all do that but if I looked very, very hard and tested all sorts of thing, I'd be able to find/fix the cause.  Long story short, it was ground loop hum which was exacerbating the 'natural' tube noises.  Utterly baffled me because I've been using a different amp in the exact same chain and never had any issues - everything's plugged into the same socket and runs through a power conditioner.  Shouldn't have assumed that it was either the amp or downstream that was the problem.

 

Choke - fitted one of these as a cheap chassis noise reduction measure.  Had to put it on its side to get it in the case, but that's hardly a tricky job.  Does it make any difference?  Maybe - who knows.  Certainly doesn't sound any worse, but my ability to do accurate A-B testing tends to fall apart if I have to do something technical (like replace a choke) between auditions.  I'm also in the fortunate position that I've got a lot of acoustic treatment and DSP of sorts in the room, and the power amps are very, very easy to drive which all makes even the most budget pre-amps sound decent.  I'm keeping the original choke so if I get very bored at some point in future I might do a side-by-side. 

 

Capacitors - switched out the outputs for a couple of these.   Still working out the best way to discharge the originals . . . 

 

Valves - picked up a couple of moderately priced regulator valves - RCA 5R4G and Svetlana 5U4G.

 

I'm justifying all this to myself as having bits to contrast/compare.

I'll AB the upgrade choke from MP soon when it arrives, but your AN choke is better built.  Im thinking of ordering one down the track.  

Caps will be an interesting one.  I did start off with the Mundorf's and later found that the Vcaps were a better all rounder.  Garry used to offer the Mundorfs SGOs as an upgrade option but since last year swapped it to the vcap odam option.  I do feel that its the best balanced/value cap to use for the MP gear but its a very subjective topic.  I use a resistor based cap discharge tool just because i am lazy..lol.

 

[sthaus]

I’m still with the stock caps 2x 8.2uf (new value instead of 2.2) and a 6.8uf on my MK3 .. just wanna try at least 300 hrs before swapping the those caps zzz I’m still burning it every day .. ! Sonic sound is a better than 1st time (muddy and lack dynamic). Any recommendations on Cap with sonic characteristics(Vdam, Mundorf, Jensen, Duelund..) 

Many thanks 

 

 

[the-chauffeur]

At the risk of sounding more dim than usual, can one of you educated folk explain what one of these is and/or how it works?  The product description doesn't really give any insight beyond plug it in and be amazed - and while that may be the case, it's clearly not magic so there's got to be some sort of science behind it.  Similarly this dude shows one working but doesn't say what it does.

 

I'm assuming that it's roughly the equivalent of a rectification step-up stage - allowing a larger tube/set of tubes to do the power rectification than would be feasible with 'standard' rectifier tubes.  What I can't quite get my head round is whether the power that's being rectified comes from the main amp (and therefore the additional box is basically a glorified tube heater circuit) or if it does the whole bit.

 

Thoughts?

 

[xlr8or]

4 hours ago, the-chauffeur said:

At the risk of sounding more dim than usual, can one of you educated folk explain what one of these is and/or how it works?  The product description doesn't really give any insight beyond plug it in and be amazed - and while that may be the case, it's clearly not magic so there's got to be some sort of science behind it.  Similarly this dude shows one working but doesn't say what it does.

 

I'm assuming that it's roughly the equivalent of a rectification step-up stage - allowing a larger tube/set of tubes to do the power rectification than would be feasible with 'standard' rectifier tubes.  What I can't quite get my head round is whether the power that's being rectified comes from the main amp (and therefore the additional box is basically a glorified tube heater circuit) or if it does the whole bit.

 

Thoughts?

 

 

It's a souped up tube rectification unit with more tube rolling options available for the rectification and what appears to be a line voltage regulation tube for stiffening up the plate voltage over the default rectifier tube. Here is what it looks like inside with its own PT and switch to toggle heater voltage.

 

[Baci]

OK, who's going first...?