| Kovax |
Haven't read it yet, but been looking forward to it for months now ...
So hard to find info and reviews on Pass Labs gear these days ... |
|
|
| Kovax |
| Nice pictures of the new UGS modules ... hehe |
|
|
| cviller |
Great circuit porn... :D
How hard are those output devices biased? ~5W per device?
And how does this sound different to fewer devices biased harder?
I'm a bit puzzled... the mantra in this forum seems to be higher current equals lower distortion, but does this still apply when the current is shared between many devices... ? |
|
|
| MRupp |
| quote: | | So hard to find info and reviews on Pass Labs gear these days ... |
Depends on the language the review should be in. Image Hifi (1/2008) in Germany has a nice review of the XA30.5 that also includes an "informal" review of the firstwatt F3. And the excellent LP Magazin (2/2008) - also in Germany - has a nice review of the new Pass Int 150. And as a bonus it has a picture of the latest (?) UGS modules that reveals the new cascoding devices :smash: |
|
|
| GRollins |
What are the plastic tabbed TO-220-ish devices edge-on to the camera?
Grey |
|
|
| noisefree |
Hi Grey,
have a look in my schematic (AX-PP-SE (v2)) in the Aleph-X builder's thread!
:-)
Regards
Dirk |
|
|
| Nelson Pass |
| quote: | Originally posted by GRollins
What are the plastic tabbed TO-220-ish devices |
cascodes |
|
|
| GRollins |
Sorry, meant the specific devices. One of the pictures appears to show a C, which leads me to think they're bipolars. I'm always open to suggestions for different critters to play with.
Grey |
|
|
| MikeW |
| Compared to a gain clone??:bawling: :bawling: :bawling: :clown: |
|
|
| Zen Mod |
according to my secret Pass Labs connection :rofl: , they're 2SC4793/2SA1837 ........
seems that Papa choose (this time ) "theymustbeubercool" approach , maybe also he scavenge 158 Kilos of mentioned critters , for ~56 greens ........
:devilr:
ps. Jaccovitty is certainly better with augmenting pic details ......... than me . |
|
|
| Nelson Pass |
Actually they were chosen by Wayne.
There is a whole interesting area of conversation, which doesn't
particularly belong here, on the subject of what to use for
cascoding transistors and how to bias them. The answers were
roughly arrived at by trying all sorts of things and seeing what
really fit best. A very tedious process, but AFAIK, the most
reliable. |
|
|
| GRollins |
| quote: | Originally posted by cviller
How hard are those output devices biased? ~5W per device?
And how does this sound different to fewer devices biased harder?
I'm a bit puzzled... the mantra in this forum seems to be higher current equals lower distortion, but does this still apply when the current is shared between many devices... ?
|
Now there's an interesting question. As with most things, you can hit it quickly and move on or take a deep breath and submerge yourself in things for a while...
Set aside the rail voltage question for the moment and assume that all other factors are held constant. The more current you can supply, the better. In a class A amp, you have to plan on delivering all the current from the quiescent bias--going to class B is cheating.
I glanced at the owner's manual and saw that the amp doubles into 4 Ohms. That means that you've got to double the 8 Ohm bias. In a 30W/ch amp, that's not really all that intimidating because the rails are fairly low and the heat dissipation is correspondingly less.
Okay, that's the quick answer. Now go a level deeper.
I believe Nelson has said that he feels that it's the overall level of bias that matters--not the bias per device. That's a slightly different way of saying the same thing I said above. Treat the amp as a classical Black Box and ignore the innards. Run the bias up as high as you dare and you don't have to worry about low impedance loads or dips in the impedance curve (which aren't a problem until you happen to hit that frequency, granted, but...).
Lotsa devices versus few devices is another question entirely. There are at least a dozen ways to look at this. Part of Nelson's view is--has to be, really, from a businessman's point of view--reliability. He puts a small army of devices in the output in order to make things more reliable in case of operator error. Even day-to-day reliability due to heat dissipation improves.
I've been thinking about this and I'm leaning the other way at the moment: Fewer output devices with more bias per device. It's not that hard to argue high bias per device, so I'll leave that alone. There's a more subtle point in that if you think about matching devices, there's always a little slop in the result. We, as DIYers, don't have the resources to buy as many devices as someone who does this for a living. If, as a result, you're limited to a matching pool of 20 units, you're not going to find perfect matches unless you've been a very, very good boy and the audio gods are smiling upon you. The practical implication of this is that you're building something like an Aleph 2, which uses six pairs of devices per channel and you've got each device going a little more or a little less while the music is playing. To some greater or lesser degree this causes distortion.
I can just see the next fifteen posts wailing about how they matched their devices to .00001V etc. etc. etc. Follow that with another fifteen posts from people worried that somehow their Alephs suddenly sound worse than they did yesterday. Not the case, guys. Your Alephs sound just as good as they always did.
What I'm talking about is the idea that if I can get two devices to match then I'm better off than having four or six...assuming that the devices can take the heat. So it's a balancing act. And since the devices are running harder, you have to consider the possibility that they will pop sooner rather than later. A not-so-inconsequential benefit is that the cumulative Gate capacitance seen by the front end drops.
Note also that the pictures also seem to show the output devices to be IRF parts. Given that the IRF P-ch devices have that odd frequency-related gain thing, then Nelson just might be rolling out his stock of IRF outputs with an eye towards using, say, Fairchild in future designs. What better way than to overbuild the outputs in current product? Mind you, I'm not saying that this is the case, just that it's a possibility.
There are a few other things I was going to throw in but I'm needed elsewhere. It's taken me three or four hours even to get this far. Bummer.
Grey |
|
|
| Nelson Pass |
Pretty improbable.
I already use Harris and Fairchild in addition to IR.
The costs of output devices as a percentage of total costs is
sufficiently low as to have very little economic influence.
In the context of performance and reliability, there is such a
thing as too few and too many. It's a balancing act between
bandwidth, distortion, and reliability. Fewer devices favors
bandwidth. More favors general distortion figures and reliability.
Of course all this is in a context. Every designer makes his
decision, and mine is here on the table.
:cool: |
|
|
| steenoe |
Nelson, what a beauty:cool:
Does all the signals run through those flat-cables? Any special type?
Looks like there is sitting a TL431 in there. Is this a F4 like circuit with an UGS for voltage gain?
BTW. If I order one, do I get one of the Pass Labs T-shirts then:D
:) |
|
|
| diy_Qui |
| I'm curious. Space does not seem to be an issue. Why PCBs are piggy-backed ? (Modular design for topology change in the future ?) |
|
|
| gl |
I recall it being stated that the AX100.5 uses some new type of output device(s). Yet here we have the IRFP240 and 9240 again. I'm confused. Do the larger amps use the new and different output device types?
Graeme |
|
|
| steenoe |
| quote: | Originally posted by gl
I recall it being stated that the AX100.5 uses some new type of output device(s). Yet here we have the IRFP240 and 9240 again. I'm confused. Do the larger amps use the new and different output device types?
Graeme |
I recall that the smaller members of the family, are different from their bigger brothers! I cant help thinking that the smaller ones are an ofshoot from the F4 (or rather the opposite, in fact), with an UGS piggy-backed!! Pretty logical development, to me.. So the smaller ones might still use the IRFP240/IRFP9240's!!
:) |
|
|
| Nelson Pass |
So many questions.
| quote: | Originally posted by steenoe
Does all the signals run through those flat-cables? Any special type? Looks like there is sitting a TL431 in there. Is this a F4 like circuit with an UGS for voltage gain? BTW. If I order one, do I get one of the Pass Labs T-shirts then:D |
The drive cable to the output stage carries signal, but at low
current. The ribbon cable is ordinary, but we do parallel wires
for reliability. This circuit is not the same as the F4, in spite of
the presence of a TL431. Yes, I will send you a T shirt if you
buy one.
| quote: | Originally posted by diy_Qui
I'm curious. Space does not seem to be an issue. Why PCBs are piggy-backed ? (Modular design for topology change in the future ?) |
Mostly for ease of production and service. I am not anticipating
a topology change in these models.
| quote: | Originally posted by gl
I recall it being stated that the AX100.5 uses some new type of output device(s). Yet here we have the IRFP240 and 9240 again. I'm confused. Do the larger amps use the new and different output device types? |
I don't recall any new devices. We also use Harris and Fairchild
versions of the IR parts, depending on price and availability. The
"P channel anomaly" encourages us to use non-IR P channel
equivalents in Common Source applications, but not Common
Drain, where the difference is minimal.
| quote: | Originally posted by steenoe
I recall that the smaller members of the family, are different from their bigger brothers! I cant help thinking that the smaller ones are an ofshoot from the F4 (or rather the opposite, in fact), with an UGS piggy-backed!! |
No. They all share the same topology.
:cool: |
|
|
| noisefree |
Hello Mr. Pass,
may I ask you what is the purpose for the two different elcap types?
Regards
Dirk |
|
|
| Nelson Pass |
| What different Elcap types are those? |
|
|
| noisefree |
The "double pack" in the bias circuit (16V/220µF)
and the "quad pack" (100V?/1000µF?) near the ground connectors. |
|
|
| Nelson Pass |
The 220's are across the bias network and the larger ones
are front end supply decoupling. |
|
|
| noisefree |
| Thanks a lot!!! :-) |
|
|
| GRollins |
| quote: | Originally posted by Nelson Pass
I already use Harris and Fairchild in addition to IR.
...Fewer devices favors bandwidth...
...More favors general distortion figures...
|
--I remember that you've mentioned having Harris and Fairchild on hand. Setting aside the use of IRF in followers, do you allocate specific MOSFET manufacturers' parts for particular products in your lineup?
--Yup, that's me. Guilty as charged.
--Well...yes, but no...you buy by the thousand, possibly even ten thousand, depending on the part. That gives you a larger pool to match parts from than someone who buys ten or twenty and has to take best available match rather than reach into a bin of .01V parts and pull out a fist full of closely related devices.
Part of the problem I've run into is that, even buying moderate quantities, the MOSFETs have at least two and often more series of stamped numbers. That kinda knocks the same-wafer, lower-distortion strategy into the weeds. I got lucky this past fall and received 100 devices in "only" two series .25V apart from one another. Hmmm. We takes what we can get.
Why things have gotten this way, I cannot say. I used to see a single series if I ordered twenty parts. No longer. From where I sit, it seems that the problem began about a year, maybe eighteen months ago. (Certain people...ahem, ahem...certain people have had their parts since the Jurassic and might not have this problem. [Okay, okay...so your Fairchild parts date from the Pleistocene...picky, picky, picky...])
So what to do? The obvious thing is to start matching at more than one current. That way, I no longer have to worry about wafers. If the boogers match, they match and I'm good to go. Yes, that will take more effort and more time and I confess that I haven't started yet--I'm just barely keeping my head above water time-wise at the moment. For the time being, I've still got some decent looking Vgs matches from the same batches and I'm getting by on those. The next time around, I'm going to at least two point matching and possibly more, because I'm a little frustrated with this broken series problem and (given my current approach of using as little feedback as possible) it'll give me lower distortion, anyway.
Using fewer devices gives me the chance to use devices that match closely, thus lowering distortion. To use more devices would necessitate loosening the matching criterion, raising the distortion.
Maybe others are having better luck with their parts buying than I am. I sure hope so.
Grey |
|
|
| GRollins |
I took a moment and looked at Digikey and Mouser. Both report having the 2SC4793. Digikey has the 2SA1837; Mouser has it on order, but with no delivery date specified. A few other places had them as well but were more expensive. I'm in no position to buy anything at the moment and won't be for quite a while--just thought it would be interesting to see of they were available without too much hassle. They are.
Grey |
|
|
| gl |
I buy unbroken tubes of MOSFETs from Mouser or Digikey. I ask for them that way and pay whatever it costs to round up to the nearest tube. The codes have been the same on a per-tube basis. Are you getting different lot codes in the same tube?
Graeme |
|
|
| Ian Macmillan |
| quote: | Originally posted by Nelson Pass
The 220's are across the bias network and the larger ones
are front end supply decoupling. |
Does this mean that there are no capacitors used for bootstrapping and that we are all chasing our tails in the Aleph X builder's thread?
Ian. |
|
|
| Nelson Pass |
| quote: | Originally posted by Ian Macmillan
Does this mean that there are no capacitors used for bootstrapping and that we are all chasing our tails in the Aleph X builder's thread? |
Perhaps you are.
There is no bootstrapping in the PL products. If I want a higher
load impedance for the UGS I suppose I would either bootstrap
the resistors which source current to the bias network or use
CCS's, but I don't want the higher load impedance - my resistors
are chosen for double duty. |
|
|
| Nelson Pass |
| quote: | Originally posted by GRollins
--I remember that you've mentioned having Harris and Fairchild on hand. Setting aside the use of IRF in followers, do you allocate specific MOSFET manufacturers' parts for particular products in your lineup? |
I use either Harris or Fairchild for the P channel Source applications,
I have no doubt that there are others equally qualified with
comparable parts. I have tried Samsung in the past with good
results and expect that Toshiba parts would also be fine.
| quote: | Originally posted by GRollins
I took a moment and looked at Digikey and Mouser. Both report having the 2SC4793. Digikey has the 2SA1837; Mouser has it on order, but with no delivery date specified. |
It's a fairly ordinary transistor - you can sub comparable bipolars.
| quote: | Originally posted by gl
I buy unbroken tubes of MOSFETs from Mouser or Digikey. I ask for them that way and pay whatever it costs to round up to the nearest tube. The codes have been the same on a per-tube basis. |
There is a slight tendency for hand wringing and sleepless nights
over matching Mosfets. The primary concern is for equal current
sharing, and once the Vgs is reasonably matched at operating
temp, you depend on the Source resistors to enforce the
sharing at higher currents. I use same lot codes and tight Vgs
tolerances because I can do so easily. This should not prevent
you guys from going ahead with different lot codes if that's what
you've got. |
|
|
| noisefree |
Mr.Pass, is there a prefered voltage type for the front end MOSFETs?
I'm searching for an alternative to the hard to find fairchild 200V parts in Germany. :-( Because the gain devices are common source the easy to get IR devices will not be my first choice.
Also I would like to ask, if you can give me a hint again what is the purpose of the 3W resistor between relay and meter-led-switch connector and of the 2,2kOhm / 3W type? Perhaps both for LED or coil circuitry?
Dirk |
|
|
| Nelson Pass |
We prefer the voltage which will not break. Since I use these
modules in X1000.5's, that would be 160V or more. For an
XA30.5, it can be considerably less, but the 200V parts are the
most common. |
|
|
| GRollins |
| quote: | Originally posted by gl
Are you getting different lot codes in the same tube?
|
Yes.
Let me pound on this one again in case anyone's confused.
1) MOFETs are poorly controlled when it comes to Vgs. It's the nature of the beast. Bipolars vary, JFETs vary, MOSFETs vary...if you want something tightly matched, you'll need to look at tubes--they're much more uniform in their characteristics than any of the solid state competition.
2) In the real world, this means that if you supply two MOSFETs with the same voltage at their Gates, one will turn on harder than the other if they're not perfectly matched.
3) This leads to one device doing more work than the other (aka "current hogging").
4) Nelson has long suggested that--when possible--DIY folks use a simple Vgs match on MOSFETs manufactured at the same time, on the same wafer of silicon. There is usually (not always!) a tiny embossed number on the body of the device. This tells the tale.
5) If you can get devices manufactured at the same time, they will generally have similar characteristics.
6) What characteristics? Well, this is where things begin to get annoying. Suppose you were to supply two MOSFETs (matched for Vsg, but from different lots) with a voltage at their Gates. If you use the voltage that gives you the current you matched for, then the devices will both give you that same current. Marvelous! Just what we wanted! Er...not so fast, bub...what happens if you change that voltage at the Gate to something higher or lower? Yikes! The bloody things don't act the same--one will give higher current than the other. But I thought they were matched, you say. Well, yes they were...at the one current you chose to match them at. This does not necessarily mean that they're matched at any other current.
(We will now pause until the rioting in the streets calms down.)
7) This is why Nelson suggests using devices from the same batch. There is a high probability that the devices from the same batch will react similarly to an increase or decrease in voltage at the Gate.
8) But what do you do if you only have devices from different batches? First off...DON'T PANIC...relax, have a home brew...it's going to be okay. You simply match the devices in question at more than one current. The more data points you have, the more accurate the match. If you want to get really into it, you can drop some money and buy or build a curve tracer.
9) If you really want to go nuts, you can match for noise or most any other parameter you might be able to think of. I used to know a couple of guys who decided to go into business building head amps. They bought an entire batch of Siliconix parts and matched them for six different parameters. Don't worry, nobody's going to ask you to do that. For the vast majority of DIY uses, just nailing the Vgs for a couple of currents will do the trick.
Grey |
|
|
| gl |
Egads man! Calm down. You answered my question with eloquence and completeness in line one. And I was only mildly interested anyway. Sheesh.
Graeme |
|
|
| GRollins |
I didn't mean you, specifically, but there are any number of other people reading this thread. As Nelson noted above, there's a lot of angst out there about part matching. Note the number of threads started because someone built amplifier X, Y, or Z, measured the voltage across each Source resistor...then had a mild case of hysteria because the voltage wasn't equal across all the resistors. "But I matched all the MOSFETs to within .00001V!" they cry. "What have I done wrong?"
Actually...nothing. The amp is fine. Sit down and listen and quit worrying. If you really want to get serious about evening up that discrepancy, then match you devices at the idle current you intend to use instead of at 10mA. If you really, really want to go whole hawg, match at more than one current.
Since I've gone and opened this particular can of worms, I want to make sure that no one comes back three months from now, having taken something out of context, and wants to know why I said that it's okay to run MOSFETs from different batches when their amp smoked the first night because one device was doing all the work. (I get e-mail from people who seem to have some pretty free-form interpretations of things I've said.) I hope to forestall some of that by flogging the idea that you've got to do a little more work during the matching stage of the game if you want to make it come together properly.
I'll still get the e-mails, just hopefully not as many.
Grey |
|
|
| Ian Macmillan |
| quote: | Originally posted by Nelson Pass
There is no bootstrapping in the PL products. If I want a higher
load impedance for the UGS I suppose I would either bootstrap
the resistors which source current to the bias network or use
CCS's, but I don't want the higher load impedance - my resistors
are chosen for double duty. |
Many thanks for the answer, I will stop pursuing bootstrapping as a way to achieve "... approximately 20% greater power output for a given supply voltage" (taken from the XA.5 literature). I couldn't really see how bootstrapping was going to do it for me anyway but then I dont' (yet) see another way either. Time to get the thinking cap on :)
Ian. |
|
|
| moe29 |
(i know this thread isn't about matching...) but,
when i built my Aleph 2, i matched via VGS to get similar fets, then i
observed the fets chosen in the working amp. Taking VGS readings
again while all warmed up and running in the circuit, i swapped out
until i got good reading all around... within .01 or something like that.
(the Aleph 2 still sounds good today) :devilr: |
|
|
| Babowana |
| quote: | Originally posted by GRollins
3) This leads to one device doing more work than the other (aka "current hogging").
|
We have Rs . . . the device of less work will be compensated by (Vgs-Vgs_th)^2 . . . even if could never reach to the same value as the upper one.
:darkside: |
|
|
| noisefree |
OK, thanks Mr. Pass,
will go first with the well known IR parts, but hold my eyes open for 200V fairchild devices!
...one fine day I will get them! :-)
Dirk |
|
|
| Nelson Pass |
| quote: | Originally posted by Ian Macmillan
Many thanks for the answer, I will stop pursuing bootstrapping as a way to achieve "... approximately 20% greater power output for a given supply voltage" (taken from the XA.5 literature). I couldn't really see how bootstrapping was going to do it for me anyway but then I dont' (yet) see another way either. Time to get the thinking cap on :) |
I don't recall using the word bootstrapping in the XA literature.
If I did, it is an error. |
|
|
| Nelson Pass |
| quote: | Originally posted by GRollins
2) In the real world, this means that if you supply two MOSFETs with the same voltage at their Gates, one will turn on harder than the other if they're not perfectly matched. |
In the real world, I find that variations in transconductance
between like devices of different lot codes is better matched
than Vgs.
If you're going to get persnickety about it, you match the devices
in the operating amplifier, warming it up, measuring and listening.
A perfect DIY activity. |
|
|
| GRollins |
I would like to spend more time on device selection than I do currently but given my time constraints, it's either that or build circuits. I choose building circuits. For the time being I'm still using the simple one-shot Vgs match, although I do match at the intended bias current.
A couple of months ago I went back through a batch of devices I had matched at a lower current and redid the matching for a higher current. There was some shifting of places back and forth, but nothing too Earth shattering. This was pretty much as expected, but it did make some minor differences in which devices I pulled. I didn't do any deep studying on it, but off the cuff, I'd say that something like one in four devices, maybe one in five, were different from the ones I would have pulled if I'd just gone with the original matching order. The devices that were left out of the new groupings were still fairly close to the groups I pulled; I could have used them without fear. Just figured I'd gild the lily a bit.
Grey |
|
|
| Manu |
I would like to ask which metal is used to pot the transformer.
Is it to shield the output stage or front end?
And ... why on the other hand Firstwatt amps for ex. obviously don't need such shieldings.
Manu |
|
|
| Nelson Pass |
| quote: | Originally posted by Manu
I would like to ask which metal is used to pot the transformer.
Is it to shield the output stage or front end?
And ... why on the other hand Firstwatt amps for ex. obviously don't need such shieldings. |
It is not potted in this case, it is banded with mu-metal, and the
reason is for low magnetic noise, mostly to avoid driving ground
wiring.
The FW amps have about 1/5 the transformer in them and at
that size, stray field is not nearly as much a problem. |
|
|
| tinitus |
| I have found that the shielding does lessen noise, but also that sound is better without shielding...seems trafos doesnt like metals, or it may be a case of disturbing the grounding...I have discouvered that sound improves when "lifting" the trafo from cabinet...and I have even found that the use of a brass bolt improves on sound...and decoupling the bolt from the cabinet is even better...I prefer wood fore my amps :clown: |
|
|
| Manu |
Thanks Mr. Pass.
manu |
|
|
| Ian Macmillan |
| quote: | Originally posted by Nelson Pass
I don't recall using the word bootstrapping in the XA literature.
If I did, it is an error. |
You didn't :) It was my (incorrect) assumption that some form of bootstrapping must be used to achieve the stated benefit.
Ian. |
|
|
| radule |
| Mr. Pass, refering to XA.5 literature, is it output stage now something like "first produced Aleph"? |
|
|
| PW |
| quote: | Originally posted by noisefree ..., but hold my eyes open for 200V fairchild devices!
...one fine day I will get them! :-)
Dirk [/B] |
Try Reichelt. I ordered 9610, and got Fairchilds. But it's better to ask them befor ordering.
Peter |
|
|
| noisefree |
Hi Peter,
thanks a lot!
Will try that and call them tomorrow!
When have you ordered your devices and which exact fairchild partnumber has arrived you?
I ask that because the fairchild 9610 is no more in production and there are new replacement types available.
Regards
Dirk |
|
|
| Nelson Pass |
| quote: | Originally posted by radule
Mr. Pass, refering to XA.5 literature, is it output stage now something like "first produced Aleph"? |
Only marginally. The primary difference is that the single-ended
bias current is quite a bit lower. |
|
|
| PW |
I ordered November 2006
Part id printed on the FET is SFP9610.
Had the first listening test of my UGS-Pre today. I will report next week.
Peter |
|
|
| noisefree |
Thanks again Peter,
have called them today and they have the fairchild SFP9610 in stock!
Have ordered a tube of 50 devices. :-)
Now I have the question if it is a good choice to combine these P-ch fairchilds with IR IRF610 complement types?
Any position to this match out there?
Regards
Dirk |
|
|
| PW |
| quote: | Originally posted by noisefree
Have ordered a tube of 50 devices. :-)
|
Thats a good quantity to match
| quote: |
Now I have the question if it is a good choice to combine these P-ch fairchilds with IR IRF610 complement types?
[/B] |
That's exactly what I did. Whether it's a good choice or not? don't know
Peter |
|
|
| Nelson Pass |
| quote: | Originally posted by noisefree
Now I have the question if it is a good choice to combine these P-ch fairchilds with IR IRF610 complement types? |
It's fine. |
|
|
| noisefree |
Very good news!!!
Thank you!!! |
|
|
| vassago |
| I play on this on this Avalon and audio aero. |
|
|
| steenoe |
| quote: | Originally posted by vassago
I play on this on this Avalon and audio aero. |
Hi vassago. Do you have something to do with Vassago HiFi?
I guess you do.
:) |
|
|
| vassago |
Yes I do.
I think you know that :o).
For the moment I used it on my Avalon Indra. |
|
|
| steenoe |
| quote: | Originally posted by vassago
Yes I do.
I think you know that :o).
For the moment I used it on my Avalon Indra. |
I will drop by for a listen pretty soon.
:) |
|
|
| Aidas |
| Yes, it is hard to find more reviews on XA30.5. 6 Moons gives very nice review on a XA30.5.I owned X150.5, X250.5, Still keep Aleph 5 in my basement for future as a classic.Next week XA30.5 should be at my house...can not wait !Thanks Nelson !Love your amps!Outstanding job! |
|
|
| jfrago |
Nelson,
I am a big fan of your threshold sa/30.9e and was wonderiing how the xa 30.5 compares to it?
Thanks |
|
|
| Nelson Pass |
I don't have an SA3.9 around any more, but I believe the XA30.5
will take it. |
|
|
| jfrago |
that sounds great.
look forward to hearing it. |
|
|
| vassago |
I just got the new topmodel from Vienna Acoustics The Music.
I cant belive how good the amp is.
This amp plays really musicaly and has alot of power in its.
Its not a problem for this amp to play such a big speaker.
I think its one of the best amp's i ever heard, i heard thaousends.
So you'v done a damn good job nielson.
:bigeyes: |
|
|
| jfrago |
I hope this isn't off thread but what speakers have people found to work well with the xa30.5's?
Has anyone found the xa30.5's to work better in either balanced or single ended modem or sre about the same?
Thanks. |
|
|
|
