[Orson Garnsey]

Hello All,

First, I am posting in this circle because most of the buzz regarding the A-L700P is found here.

I recently purchased a 700P because of its reputation for good sonics on "the cheap" and wanted confimation from my own ears. I modded the amp out of the box with Nichicon "Muse" electrolytics in key positions, removed the center channel board and wired the inputs directly to the module.

After about 80hrs of playing time, I must say that it's easily worth the $$ and much more. The 700P's primary strength, IMHO, is soundstaging; tall and wide, even at low volumes (holographic). Other notables include superb pace and detail.

However, the midrange warmth/richness of which many speak is not apparent to me. The lower frequencies are prodigious, but somewhat "boomy" and the HF extension is on the brittle side. This is in comparison to my CIAudio D-100 monoblocks. I'll admit that the comparison is not fair, but it's the only one at my immediate disposal. The D-100s have much better low-end control, far better mid-range, much smoother HF extension and are quieter.

The 700P, however, does have "better" soundstaging at low to moderate volume. The D-100s, like a true thoroughbred, blow away the Teac as the dBs climb. In my system (Klipschorns) the 700P sounds very grainy above 85dB (some music should be played LOUD).

Other amps I've had within the past year include a Bryston 3B-ST, Monarchy Audio SE-100 Delux monoblocks, and a Bryston B60. The 700P compares best to the B60.

Note that I currently use a passive volume control, which may not be the best match for this amp.

Does anyone here have a similar opinion? And, how does the battery power mod affect the grainy character and my percieved lack of midrange "air?"

Thanks.

[mcgsxr]

I will not cross the boundaries of promoting another modder, here in Vinnie's Circle where you have chosen to post.

1 - I totally agree that the stock Teac with less than 130-150 hours has a grainy treble thing going on.

2 - mods can totally remove that grain, and Vinnie is one guy who can take care of that for you.

3 - DC power is all the rage right now - please, I don't mean that it is a fad, or that it might not be perfect for you, I just mean that it is a popular mod for tripath amps.  DC conversion is one way to achieve some of the results that you are looking for, but in my experience it is not the only way.

It is a great little amp stock - modded, there are surprising capabilities lying within.

Good luck with it, I have 2 highly modded Teacs, and really do like them.

[Vinnie R.]

And, how does the battery power mod affect the grainy character and my percieved lack of midrange "air?"
..

Hi Orson,

The battery power conversion + the other mods that I perform removes the grain from the top end, results in more punchier and tighter bass, , and removes the midrange congestion (the lack of air that you speak of).  

The result is a much improved sounding amp from top to bottom!  

http://www.redwineaudio.com/Teac_AL700P_mods.html

I will not cross the boundaries of promoting another modder, here in Vinnie's Circle where you have chosen to post.

Mark, you are a classy guy!  Thanks  

[Dmason]

I am now in a position to vouch for the fact that to my amazement, the Battery + Optimal Mods Job on the Teac, it now bears absolutely no resemblance in sound to the original, which I only ever listened to brand new, but the battery one I have has no more than about 25 hours on it. Gawd only knows how it goes after about 300 hours.

An excellent job and even better result! A++ ValueKing Component Award

[Paul_Bui]

Dan,

Could you tell any differences between the mod TEAC and your Clari-T?


Thanks in advance.

[Tubo]

Vinnie,

In a thread called "Recommend me easy Teac mods please", in Multichannel Audio, Bfitz wrote,

"One issue to be aware of with the TEAC is the output filter  
Basicly, you need to know what your tweeter impedance is above 5kHz.
The Teac really wants to see a flat 6 ohm impedance, otherwise, it will roll off early (for say 4 ohms) or having a rising response (for 8 ohms or greater)
"This means a tweeter zobel (cap and resistor across +/- leads) can tailor the amp response rolloff, and significantly change the measured response. I point this out as I was looking at using using these with a 4 ohm load, but would not recommend that now, at least above 5 kHz. With a 4 ohm load, it starts rolling off at 8kHz, and is down about 3.5-4 dB at 20 kHz.
 
"The output filter, BTW, is not the one recommended in the Tripath 2050 data sheet. I have new inductor toroids inbound for experiments to replace the stock ones.
-bob"

A couple of posts later, Bfitz writes again,

"Has anyone tried air core or type 2 low mu cores (recommended by tripath) on the outputs?

"Before I went all gung ho elsewhere, I would make sure the components that sit between the amp chip and the loudpeakers are the best they can be. Those stock inductors are not impresing me too much, nor are the stock output caps. I would go to single crystal copper or silver wire wound on type 2 cores there, and all polypro caps, before I spent big bucks elsewhere. Just watch, next week some modder will be offering it, after reading this."

Ignoring for a moment the last sentence in the quote above, is Bfitz correct about what Tripath recommends for the output, and would making the mods he suggests result in a smoother top end and a better match with most speakers?

I have noticed that with my 11-ohm (nominal) and 15-ohm (nominal) LS3/5A's the stock Teac has a rising frequency response, conforming to Bfitz's comments.

Thanks,

Al Lau

[Vinnie R.]

s Bfitz correct about what Tripath recommends for the output, and would making the mods he suggests result in a smoother top end and a better match with most speakers?

I have noticed that with my 11-ohm (nominal) and 15-ohm (nominal) LS3/5A's the stock Teac has a rising frequency response, conforming to Bfitz's comments.
...

Hi Tubo,

First, let me state again that once switch-mode power supply is complete removed and everything is converted to battery, I found the harshness/grain in the top end goes away, bass becomes tighter with more punch, and the midrange congestion also goes bye-bye    
It sound more tube-like, but with rock solid bass, very fast transient response, and free of noise.

Using 11-ohm or 15-ohm speakers, yes, you can tweak the LC filter on the output to work optimally with such a load.  However, everyone is using different speakers  

The easier approach to try out is using a resistor in parallel with the speaker outputs to drop the nominal speaker load from, say 15-ohms, to the "ideally-flat 6-ohm response."  This is a lot cheaper, and you can experiment with a few different resistor values to find the optimal setting to your ears.  For example, with 15-ohm (nominal) speakers, try a 10-ohm resistor (15-ohms in parallel with 10-ohms equals 6-ohms).  If you drop the 10-ohm resistor a little, say, to 8-ohms, the total resistance will drop closer to 5-ohms.  According to the datasheet, this should roll off the top end a little, but ALWAYS trust your ears (ie, maybe it won't roll it off, or maybe it will just make is sound better... to you!)...IMO, there are too many variables here to just go by datasheet measurements, but I can see where Bfitz is coming from by wanting to tweak the output filter.


"I would go to single crystal copper or silver wire wound on type 2 cores there, and all polypro caps, before I spent big bucks elsewhere."

My approach was to clean up the power supply first, let the unit burn-in, and then listen to how it sounds, comparing it to the stock unit.  The improvement was huge, so I was very happy with it!  

Hope this helps,

[BFitz]

Al

Hi, glad you found those mod topics stimulating.
Many, if not most voice coil based drivers have a rising impedance at high frequencies, as the inductance of the voice coil makes itself evident. Hence the need for a zobel (resistor + capacitor across the +/- leads)  to counteract the impedance rise. To me a resistor *only* is less desirable, as it will soak up power at all frequencies.  And it won't fully counteract the rising impedance. The idea is to pick zobel values that will create a "downslope" that counteracts the driver impedance "upslope". The tripath recommended output circuit has an optional zobel shown, with final values left to the user.  
So you can use a speaker zobel as a "tweak" that will alter the sound to your liking when using the TEAC digital amp.
On power  - no doubt a battery would sound better than a switching supply. Another option which I favor is an external linear supply in a separate enclosure.  
Another thing to take a peek at is the heatsink on that TEAC. Both of my boards have about a 1/16" gap between the chip and heatsink, partially filled in by heatsink compound    This mean the chip is only partially transferring the heat through a bridge of white compound.
In my opinion, cooler chips sound better, so on mine I did this - cleaned the compound off the heatsink and chip. Filed down the two raised points on the heatsink that contact the board until it *just* touches the chip - then I re-applied the heat sink compound and screwed it down.  
I'll post measurements in the digital area later - I plan to do distortion vs. power/frequency on the stock inductors - that will probably be interesting.
bob

[Vinnie R.]

In my opinion, cooler chips sound better, so on mine I did this - cleaned the compound off the heatsink and chip. Filed down the two raised points on the heatsink that contact the board until it *just* touches the chip - then I re-applied the heat sink compound and screwed it down.  
.

Hi BFitz,

Thanks for posting this tip...very good idea!

Regards,

[Tubo]

Bob,

Thank you for your pointers. I have learned a lot from your posts, and...I guess I'll reveal some of my ignorance. Until I read your discussion of the heatsink and looked at one of the Teac boards, I did not realize that THE Tripath chip is mounted on the other side of the board!  

There is a good reason why I am not doing the mods myself and having Vinnie do them!

Al

[DeadFish]

This seems as good a place to put my recent observations on my new Teac as any.
I got this rascal hooked up to Altec 19's with a Clarinet tubed pre.
Sunday it hit the 150+ hour mark.  I pretty much ignored it playing until then.
I have taken the 'center' channel board out of it.

I've (so far) listened to 3 albums of my select stable for listening to gear, and so far, so 'decent'.
Contrary to Orson, midrange is the strongest point on my amp.  It seems real normal and precise, throughout the cds I listened to.
My first album up was "Heritage" by Darol Anger.  I like this album a lot as it offers music I like, plus some decent bass and a lot of fiddle playing.  The fiddle and some female vocals on it can be a real challenge to some gear, reaching that strident, almost painful place if the mix on the gear isn't right.  The cuts of 'Pretty Polly' and one by Willie Nelson take the highs right up to, but not crossing that painful threshold, and I kept waiting for it to cross that line, but it didn't happen.  A caveat to the amp was that a number of known 'flaws' that sometimes show up, did, but they are in the recording, so I had no complaints with it reproducing what I know is there.
Second up, was one cut from Rob Wasserman's 'Duets' with a version of 'Over the Rainbow' characterized by Wasserman on bass and Graphelli on violin.  Once again, that fiddle almost took itself to the edge of pain, but stopped short.  The bass however, seemed unbalanced in respect  to the fiddle in that it didn't seem as loud, and I don't think I remember the volume between the two artists being that imbalanced.  Another aspect of the bass is that the notes seemed short, lacking in the extension I am used to hearing.  The notes seemed precise, but lacked a certain 'sustain'.
Thirdly, I jumped around on the first 'Sopranos's soundtrack.  The first cut is the openner for the HBO show and I have noted it to have bass out the kazoo. It was missing to the extent that it reminded me of the same cut played on my actively biamped Vandersteens, the one time I forgot to turn on the amp for the bottom end.  It was really horrible, for *that* particular cut.  As I listened to more of the album, it was not so bad, but that first cut is capable on both my Vandies and Altecs of vibrating your testicular foundations, and it was noticably lacking in that power.
I could go on about this, but I think you get the idea.
Throughout the album, it seemed to be missing about 5% of the bottom end of the bass as heard on Cream's "I Feel Free' and Springsteens 'State Trooper'.
On the upside, the whole presentation was fast, and I had decent sense of soundstage and depth.
I would remind you, dear Reader that this amp has at best 160 hours on it now.  I still expect some gains, but what is missing seems to fit right into what  the variations of modding approach to alleviate.

Of course, YMMV.

Hope this helps someone.  I still don't regret buying the amp, at all.

Regards,
DeadFish

[jhenderson010759]

Hi -

I have two, stock AL700's.  

Has anyone performed any standard AC performance measurements on Red Wine-modified AL700 amps to determine if these modifications produce a quantifiable improvement in THD, SINAD or SNR?  

Thanks in advance

[JLM]

I just got my stock Teac from Needle Docter (shipping seemed a bit high, but it was nicely double boxed) and had only a couple of minutes to play with it to make sure everything was working:

1.  Gawd! the amount of bass really makes my Clari-T sound anemic (and the Clari-T made SET amps sound anemic).

2.  Lots of higher frequency hiss/noise, the Clari-T spoils you rotten with its totally black background.

Dr. Dan was right, the Teac makes a good match for my Bob Brines FTA-2000 speakers (Fostex F200A full range driver based floorstanding mass loaded transmission line design).

I'm tucking this away until we move, then I'll send it to Vinnie for mods.

At this point I've lost most of my interest in the B200 OBs!

[Vinnie R.]

1. Gawd! the amount of bass really makes my Clari-T sound anemic (and the Clari-T made SET amps sound anemic).
..

Hi JLM,

Upgrading the input coupling caps of the Clari-T will certainly fill in the low frequencies...giving you bass fullness that is more like the Teac, but yes, the Teac's 30wpc (if your speakers need it) certainly has some seriously good bass!

Send it on over for mods whenever you are ready!  

In the meantime, enjoy!

[JLM]

Thanks Don (Nodiak) for the heads up on sourcing the Teac!!


Allow me to flesh out what I posted above...

I've been into serious audio for 25 years, have never owned tubes, switched early to CD, and have always been a big fan of mass loaded transmission line designs.  I listen to mostly jazz and classical at moderate levels.  My priorities are tone, detail, then imaging.

Last year I had the opportunity to try my speakers (rated 30 - 20,000 Hz in room, 90 dB/w/m, 8 ohm, single driver, mass loaded transmission line floorstanding design) and in my 11 ft x 19 ft x 8 ft room with these amps:

1.  Decware Torii (12 wpc push/pull, based on EL84 tubes, hand built, $1500)  good sound, but bass was exagerated/uncontrolled and had realiability issues.

2.  JVC digital amp (100 wpc, from Mark in Canada, thanks but don't recall which model number) after the acknowledged 300 hour break in sounded "stupid good" for the money, but was cheaply built.

3.  A homebrewed gainclone (separate power supply) more of a solid state sound but with tubey influence to take the edges off.  Power supply hummed badly and it picked up 94.9 FM something terrible.

4.  My old Rotel stereo A/V receiver (100 wpc solid state, $700)  the workhorse of the group, offered the best controlled, flattest response bass of the bunch, but nothing exciting.

My stock Clari-T (second input added, mini-toggles moved to the front) blew all these away in every term except ultimate output spls, especially with its black background and deep/full/controlled bass.  That the stock Teac would blow the Clari-T away in the bass department amazes me.  In the back of my mind I always knew that my speakers should be able to do more/deeper bass (this tight/full/tuneful bass is very addictive).


Vinnie, why does your site mention the very nice volume pot would be located on the back of the Teac?  That's a "no-go" in my book/situation, as like many, it would go into a rack and so make it inaccessible for routine use.  Would much rather add a $160 pot versus a more expensive pre-amp.

[Vinnie R.]

Vinnie, why does your site mention the very nice volume pot would be located on the back of the Teac? That's a "no-go" in my book/situation, as like many, it would go into a rack and so make it inaccessible for routine use. Would much rather add a $160 pot versus a more expensive pre-amp..

Hi JLM,

I suppose it can be mounted to the front, but would need to be on the left or right side of the front (can't be on the center because there is plenty other "stuff" in the way).  If appearance is important, it might look strange to have a volume knob on one side of the front...but yes, I'm sure it can be done.  

You'll also need to run the cable from the RCA jacks in the back of the unit to the front of the unit, and then back to the amp board (towards the back again).  When I install the volume control on the back, I install it right next to the RCA jacks, so the signal path is kept very short inside the unit, which is ideal.

I don't use the Teac in a rack, so adjusting the volume from the back is a piece of cake, but I see your point about mounting in a rack.  Maybe a simple external passive preamp would do the trick for you?  

Getting back to your Clari-T, if you want to take it to another level in the bass department...send it on over for the larger uF input coupling caps (Auricaps).  The unit will certainly sound more full in the bottom end, and the Auricaps will also sound better in the mids and highs.  

Still, if you need more power, the Red Wine Teac has some serious bass (much better control than the stock Teac), and the HF hash that you hear will go away too    

Regards,

[mcgsxr]

JLM - you had access to the ES-1 JVC receiver - my own experiences with that receiver are parallel to yours - I ended up selling it to my best friend, for use in his whole home audio system.  He is very happy with it.

Teac - nice to see some folks catching on!  I have really enjoyed these amps for getting on a year now, and it is fun to see some others discovering the goodness that lives in there.

The highs will smooth in time, and as Vinnie suggests, getting it modded by someone, will bring out the real value hiding in there - I am supremely happy with mine.

I am still considering the DC mods to my 2nd one, and hope to gain some insight to the "cult of the battery" when powerbench comes over, and brings his Clari-T!

[Dmason]

I can attest to the Cult of the Battery. Turns the little thing into a demon, what with all the added mojo con Vino. The bigger the T, the longer it takes to work in, but it is beginning to mature into something really nice, just in the last several days. The highs are sorting themselves out, the mids are nicely fleshed, and the bass is something else, "addictive" is a term used here; tight, fast as hell, and deep, tuneful, grab your attention type bass, which puts a whole new spin on certain types of material. I chose last weekend to put it thru the UFO TOFU test with a few people along as control subjects, for an experiment in what I call, "Flecktonian Physics," -how an amp/speaker combo "deals" with the Wooten brother's rhythm section. ALL were thoroughly convinced this was some of The Best bass/percussion quality they had heard, and one, who "upgraded" recently from a 250 watt amp to a 350 watt Belles amp, (350 being inherently better than 250 by 40%, according to current marketing methodology) was obviously miffed: 'how could such a thing happen.' --he was the only one who, despite his innate and relentless curiosity, asked NO questions  Interesting observation about the amp, and its effect on the Bigger id mo Betta, yuppie/label whore psychology. PAF is the social equation pertinent to this person's reaction, but the amp on the other hand, appears to be able to control drivers in the same way Jumbo Amps, muscle amps can. Can you tell I like it?

[Ken D]

Dmason,

I read your posting in June about having Vinnie modded 700P.

Are you ready to offer insights comparing modded 700P and your modded ClariT.

I have 50 hours on modded ClariT.  Feeling that my 88db Spendor 1/2 may need the extra power of the Teac 700P.

Any thoughts on whether one gives up anything by using the Teac?

thanks

Ken