This listing was ended by the seller because the item is no longer available.

 
Posts to:
Worldwide
Delivery:
Please allow additional time if international delivery is subject to customs processing.
Visit Shop:
Vintage Audio Lab
 
Posts to:
Worldwide

Details about  Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version

Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version See original listing
Valab-TDA1543-NOS-USB-Re-Clock-DAC-MK-1-Luxury-Version
Item Ended
Item condition:
New
Ended:
26 Mar, 2012 08:02:21 BST
Price:
AU $260.00
[
History:
]
 
Approximately £142.61(including postage)
Postage:
AU $30.00 (approx. £16.46) Other Int'l Postage (see description) | See details
International items may be subject to customs processing and additional charges.  help icon for delivery - opens a layer
Item location:
Taipei, Taiwan

Description

eBay item number:
270625100373
Seller assumes all responsibility for this listing.
Last updated on  28 Mar, 2011 08:22:13 BST  View all revisions

Item specifics

Condition:
New: A brand-new, unused, unopened and undamaged item in original retail packaging (where packaging is ... Read moreabout the condition
 

Valab Non-Oversampling USB DAC using TDA1543 --- Ultra low jitter version with dual 1ppm tcxo inside

#10 revision Re-clock and Enhence Power Supply version 


Why non-oversampling DAC?  ------  'oversampling'  kill music!
  
   
You may not know, the actual digital signal recorded on your CD title is 16bit/44.1k format. Yes, never doubt it! Then why almost all modern DAC feature 24bit/96k or even 192k specification? In modern digital recoding studio,  music will be recorded in new 24bit/192k format but when they need to 'write' onto CD, these information rich formation must be degraded into old format. These 'New' DACs will try 'restore' the degraded back to more informative format using some talent algorithm work out by smart mathematician. ----- That is problem!  why? All music you hear from CD will be processed by some smart algorithm, then you hear the artifact sound ---- actually bad sound!

 
  My over-opinion? No! If you are a experienced audiophiles, you will find if these cd players or DACs use the same dac chip inside, they all will have very closer sound features, even their analog circuits designs are quite different. Why? You hear the same artifact derived from the same talent algorism.   
 
  These artifacts contamination did hurt your audio enjoyment! Why, they mask real tone color and even 'atmosphere' of music player.  You do not believe!? Try to find CD records which also have vinyl LP version, compare music from vinyl and CD. You will know how bad these
artifact sound is!

Back to vinyl record?
   
   No! Vinyl LP really too troublesome! Listening music should be easy and relaxing.

Non-oversampling DAC is a compromise answer.
   
   NOS-DACs may be an acceptable answer to CD music. Why? No artifact anymore from these NOS-DACs. You get non-refined music recorded on CD although it is still a degraded music. But in my experience, it is still much better than artifact juck.
  Why? 'modern' dac can not De novo generate right music signal from degraded records on CD, but rather add mathematical generated fill-in bits into your music. 
  So NOS-DAC is a can-not-but choice!


VALAB NOS-DAC TDA1543 --- simple elegance
   
  All NOS-DACs are simple. because these old NOD dac chips are so small and simple IC with few pins and only need simple circuit to work well.

  TDA-1543 may be the most small but tough one. It is a real vintage chip developed by Philips 2 decades ago. We choose it to implement our own  NOS-DAC.

  No special innovation on this chip for it is too simple. What we should do is try to extrapolate its most potential! How?
 
1. Keep most accurate digital signal and feed to TDA1543 in low jitter fashion.
    DIR9001 digital receiver is the answer for this propose. DIR9001 is a new modern IC, much more expensive than that popular CS8412/4/6 used in all other DAC. Much more music details keep and accurate sound you obtain.

2. Paralleling DAC chips.
    We parallel up to 8 TDA1543 chips as you see on Fig. 4.  8 paralleling did enhance performance, get better resolution and lower output impedance. 

3. Profuse power supply
    30W sealed military grade power transformer was used in this DAC, it can offer up to 15 times required electronic power. No vibration, heating from this transformer. In rectification circuit, we use best sound 1n5062 diode, this is most credit diode which is popular in audio tweaking. It do signicifantly improve sound quality, more smooth and natural sound. Expensive LT1084 5A voltage regulator
and Rubycon capacitor were used in power supply section to offer clean and low drop voltage to tda1543 and dir9001 chips.

4. USB receiving for somputer based source
    We incoporate USB receiving capicity to our new version of 1543dac. Unlike other USB dac use pcm170x chip which integrate USB reciving and dac in one chip, which is very low cost and low performance. Our approach of USB DAC use very decicate design, using independent USB recieing chip and get I2S digita; signal feed into TDA1543 chip.

5. Precision Clock
    In order to get best quality digital signal for TDA1543 chip, we integrate independ precision clocing and
redata circuit for digital reciving. You will nerver find any commercial NOS DAC have so dedicate digital design. No matter what price they sell! We inverst our best efforts to extrapolate potential of TDA1543 chip. Our implementation may be best TDA1543 based DAC in market.
We custom order 1ppm 12.0000Mhz TCXO for our most update version to fulfill our promise for building best sound NOS DAC.
In Figure 3, 4 and 8 are our new expensive precision 1ppm 12.0Mhz TCXO, it will be basel part in this dac.
This muxt be most effective and expensive upgrade we ever applied on this product. 
 
6.
After several month of selling this dac, we accumulate many know how in parts choice from our customers. Key components usage list below.
 
  a.  First stage filtering capacitors: Three Rubycon XYF 1000u/35v Long Life/Low impedance 105 degree C tolerance
    b. Decoupling capacitors for digital circuit chips: Eight PSC-470uf 16V solid polymer (os-con) Low ESR/Low impedance 105 degree C tolerance   http://www.chemi-con.com/files/PSC.pdf
    c. Decoupling capacitors for TDA1543 chips: Eight NEC TOKIN 10uf/25v SMD type capacitors, one for each tda1543 chip
    d. Adjustive capacitors for voltage regulator: Two Rubycon XYF 25uf/25v Long Life/Low impedance 105 degree C tolerance
    e. Analog output output capacitor: Two metal can Tantanium 10uf/16v
    f. Digital input coupling capacitor : Two metal can oil filled 0.01uf/200v

7. 2009 new version with new layout by Taradac research group, significantly shorten signal path and use chassis chassis as heatsink, it will have much better heat dissipation efficiency, keepping dac chip cooler and long time stable. 

8. New 2009 March version without clipping/distorsion in high output digital records.

9. New re-clock circuit was added on this dac.
I2S bus data from both cm108 usb receiver or dir9001 (both usb and spdif signal) was re-clocked and then feed into dac chip. This re-clock module use 1ppm 33.8688 tcxo and indendent power supply voltage regulator to get best recolck performance.

10. New off-board R-core power supply transformer and build in EMI filter offering profuse and clean power supply for this dac. This is new design make this dac can achieve less than 5mv noise altitude.  More detail, headroom and vivid sound you can hear!

11. Dimension of this dac is 125x 220x 50 mm (W x L x H)

This dac use tda1543 chip, it is a 'vintage' dac chip which was developed 20 years ago. Its signal/noise ratio is about 90db. Modern dac chip always have over 110db S/N value or higher. So this dac will not be a dead quiet dac like your modern cd player! You will hear minor noise, major from right channel. It is not a defect or poor building quality. It is theoretical limitation, no way to remove noise without remove music signal. This noise will not audible when misic is playing. So actually it really do not interfere your music listening. I ever try to use some filter to remove this noise, but also remove vivid and analog sound of this dac. So I decide to keep minor noise but make this dac a great musical and natural sound device. 

If you can not agree any noise from dac, please do not buy this dac. This dac only for someone appreciate it.
It use dac chip developed 20 years ago, it is a real
vintage audio device. So before your order, please make sure what you will get.
You can query google for 'valab nos dac'. You will see what it is.


This is not a high cost DAC, because very few parts required. We sell itab at low price. Actually no even cheaper DAC in audio market can you find. While it may be very indispensable equipment in your audio system. If you get used to sound of NOS-DAC. You will 100% agree what I say 'artifact junk' about these modern dac or cd player.


This simple and small NOS-DAC do have most delicate design and very very good parts choice. You can take it to compete other much much expensive DACs of your friends. You will be very happy.


Why we develop this #10 revision version? Sometimes we got 'ship-back' dacs, their buyer clain this dac have humming noise! While in our audio system and equipments, no audible noise and measured noise less than 10mv or less. We were confused to this trouble for long time.
Finally we know the real problem, home electric power of some users were very poor, without right grounding and full of noise. So we develop this enhanced power supply version with noise-resistance/low-coupling power supply and add an EMI power filter. This new desiagn make our #10 version become bigger and heavier than previous version but it do show high resistance to poor quality power supply.

We will keep selling #9 revision version, if your home power supply is good or you have power conditioner in your audio system. You do not spent more money to this $10 revision version, #9 version is right choice for you.   

Shipping Worldwide: This product will be shipped by EMS air express with on-line tracking and insurance.

Combined shipping fee for multiple items of all my products is welcome and will save you lots of shipping fee.  Please query me before your bidding.

We have both 100/120v US version and 220~240v EU version, please assign which one you need after your order. 

Feedbacks Listing:

Positive feedback ratingGreat DAC, good sound, fast delivery. Highly recommended!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270536624741)  baritonolirico ( 59)

Positive feedback ratingReceived item very fast. DAC sound as described.
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270536624741)  razzle168 ( 38)

Positive feedback ratingProduct is as described and very awesome. Delivery and handling very fast.
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270520408624)  ykhui733 ( 2 )

Positive feedback ratingExcellent product, fantastic customer service, RECOMMENDED!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270505761201)  hibbert_it ( 54)

Positive feedback ratingVery well packed and arrived rapidly -- sounded good straight out of the box!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270520408624)  7004thomasm ( 31)

Positive feedback ratingFast shipping, product as described, affordable prices. Recommended!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270505761201)  joonasdf ( 8 )

Positive feedback ratingPut fun back in digital audio! Sounds almost analog. Highly recommended!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270505761201)  dubjazz ( 124)

Positive feedback ratingGreat sounding, very vell built DAC ... I'm delighted!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270490109062)  internetfraudattorney ( 408)

Positive feedback ratingExcellent delivery and the sound of the DAC- I will get rid of my CD player!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270490109062)  jendapl ( 2 )

Positive feedback ratingsuperlative all the way!!!!!!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270490109062)  scottsan ( 21)

Positive feedback ratingExcellent, super fast shipment only 4 days! Great sounding DAC too!!!!!!
    Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270490109062)  jomy23 ( 51)

Positive feedback ratingExcellent packaging, shipped almost immediately. The device works perfectly.
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#300350833856)  alkasar92 ( 3

Positive feedback ratingFast shipping, excellent communication, well packed and good sounding DAC !!!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#300350833856)  audiohdg ( 91)

Positive feedback ratingLivraison éclair pour un appareil qui en vaut le détour - excellent ebayeur
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#300350833856)  occazouest ( 111)

Positive feedback ratingQuick shipping with tracking # Great upgrade for Sonos
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#300350833856)  gtspec ( 327)

Positive feedback rating!! WONDROUS GOOD DAC !! I can't thank you enough ...
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290345437570)  fb.fccl ( 248)

Positive feedback rating***Great product, ULTRA FAST delivery, Highly APPRECIATED!!!***
  Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290345437570)  lukaskite ( 27)

Positive feedback ratingUltra-fast shipment; Best DAC under USD10000; top of tops eSeller;A++++++++++++
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290345437570)  dowayo ( 211)

Positive feedback ratingYou make a really nice DAC, indeed. Sounds great in my system. Thanks!
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290339718170)  hubert_offner2xx6 ( 56)

Positive feedback ratingGood DAC, quiet background, requires full 1 week break-in, replaced a Beresford
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290334661822)  alan.t.hope ( 3 )

Positive feedback ratingFast international shipment. Fantastic sounding DAC. Thanks !
   Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#300334804217)  tamago-now ( 275)

Positive feedback ratingOut of close to 100 transactions - the best one I've ever made. DACalicious A+
     Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290334050423)  soulpianoman ( 80)

Positive feedback ratingSuper product for the price, 3 day international shipping, superb seller, A+++
    Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270432592748)  alta_tom ( 42)

Positive feedback ratingtres rapide, produit conforme, merci
    Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#270432592748)  totoche40-2008 ( 12)

Positive feedback ratingExcellent Ebay, super fast delivery and excellent DAC...A++++++
    Valab TDA1543 NOS USB Re-Clock DAC MK-1 Luxury Version (#290334050423)  aro101 ( 33)

Positive feedback ratingwhat a wonderful DAC! This seller deserves the highest recommendation!!
   Valab NOS USB DAC & Pure Silver Coaxial Digital Cable (#270354619597)  carlhsieh ( 206)

Positive feedback ratingVery good DAC,quick shipping, good communication. Thanks Kevin.
   Valab NOS USB DAC & Pure Silver Coaxial Digital Cable (#270354619597)  megmeg8932 ( 31)

Positive feedback ratingGreat quality product, amazing sound, quick delivery, I want the 6L6 amp!!!!!!!!
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270354676012)  wjekat ( 202)

Positive feedback ratingExceptional DAC...I love it!!! Wonderful sound...like liquid...smooth..thanks!!!
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270358204448)  seiryu7 ( 42)

Positive feedback ratingTotally perfect ! Super fast shipping and good comm.
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270359765470)  tpicq ( 36)  

Positive feedback ratingIMPRESSIVE PERFORMANCE Thanks!!!
   Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#290299625365)  fe_bunz ( 410)

Positive feedback ratingThe dac is sounding so great
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270354676012)  simca423 ( 2 )

Positive feedback ratingExcellent product, quick o/s ship, value 10/10, very happy customer
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#290299625365)  valvefan ( 297)

Positive feedback ratingUNBELIEVABLE sound & quality, VERY FAST shipping, GREAT person to deal with !!!!
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#300296090417)  svetlanov ( 114)

Positive feedback ratingGreat Sounding Dac and Wonderful service by Kelvin
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#290287221585)  crumpler09 ( 1 )

Positive feedback ratingExtraordinary dac, very natural and musical, super fast delivery.
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#300296090417)  alberto30146 ( 8 )

Positive feedback ratingExcellant product! Very very good sounding DAC! Fast Shipping.
    Valab NOS USB DAC & Pure Silver Coaxial Digital Cable (#300293612900)  dieaudioite ( 163)

Positive feedback ratingThis DAC sounds about 98% as good as my $1000.00 unit.
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#300296090417)  stevenc8680 ( 395)

Positive feedback ratingWOW -Superfast shipment - Item well packed - DAC is sounding GREAT!!!!!!!!!!!
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#290296754387)  8sandaces ( 23)

Positive feedback ratingAmazing DAC really does sound like analog. Exactly as described. A+++++++++
   Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270338834760)  technoskeptic ( 572)

Positive feedback ratingGreat unassuming DAC that beats a Bel Canto DAC3 in my system. Thanks Kevin!
    Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270338834760)  hung1151 ( 20)

Positive feedback ratingValab wins,MF beaten.Fast shipping but the customs office slow and not cheap :).
   Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270331563053)  trymarczyk ( 18)

Positive feedback ratingVery Very good DAC, Fast Shipment to UK, good communication. Recommended ebayer
   Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#270338834760) jjlucas76 ( 54)

Positive feedback ratingFantastic sounding DAC with nice build quality! Very fast shipping & great comm.
   Valab NOS USB DAC TDA1543 Low Jitter 1ppm TCXO Inside (#290290173465)  cerdelyi ( 27)

Positive feedback ratingUnique natural sounbding DAC. Great professional seller A+++++++
    Valab NOS USB DAC & Pure Silver Coaxial Digital Cable (#290285377743)  pieralfonso2005 ( 446)
  
Positive feedback ratingGREAT ITEM,FAST SHIPMENT,GOOD INTERNATIONAL TRANSACTION,THANKS
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#290270822819)  talisman71 ( 144)

Positive feedback ratingReceived item in 6 days to the US. Great item! Would buy again. A+++
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#290276473993)  bwestlind ( 43)

Positive feedback ratingPerfect. Thanks Kevin. A+++++++
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#290276473993)  ferguson5030 ( 86)

Positive feedback ratingIncredibly quick delivery.excellent communication .dac sounds great. brilliant.
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#290276473993  azelium ( 253)

Positive feedback ratingVery serious and reliable seller, recommended, A+++++++++
    Solid Core Pure Silver Analog Interconnects kt88 el34 (#300267812074)  redeagle38 ( 397)

Positive feedback ratingA very special and musical sounding DAC. Arrived fast.
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300271121642)  jordand2 ( 29)

Positive feedback ratingSmooth transaction, fast shipping, courteous replies, great DAC. AAA+++ 
    
Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#290270822819)  fishline ( 3 )

Positive feedback ratingUnbelievable quality for price. This and Macbook sound better than Rega Planet.
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300266925387)  gdtrfb ( 181)

Positive feedback ratingGreat Dac, well built, quick shipping, good communication. Thanks Kevin.
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300268960627) seaways1075 ( 1 )

Positive feedback ratingExcellent DAC and excellent international ebay transaction. Thanks very much.
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300268061066)  colingibbons ( 155)

Positive feedback ratingThanks for the fast delivery and communication. For the price sounds incredible
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300268061066)  pleikka ( 36)

Positive feedback ratingThis DAC is incredible. My $1,200.00 Audiosector DAC was beaten by this gem
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300266925387  annemcrunning ( 1 )

Positive feedback ratingAmazing DAC!Smooth but revealing presentation.Best of NOS.Also excellent service
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300268061066)  quicky_q ( 134)

 Positive feedback ratingOne of the best DACs I have ever owned regardless of price
     Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300266925387)  audiojoy4 ( 1440)

Positive feedback ratingMost musical dac I've ever owned. Great communication. Fast Shipping. A+++
    Valab NOS Nonoversampling USB DAC TDA1543 Low Jitter (#300267161555  miguel10744 ( 18)

Start selling to international eBay sites.
eBay Cross Border Trade powered by MerchantRun GlobalLink

Questions and answers about this item

No questions or answers have been posted about this item.




00000

Place bid

Time left:
Current bid:
(Approximately ##1##)
Postage:
Import charges:
Your maximum bid:
Your maximum bid:
Please read the full listing. By clicking Confirm bid you commit to buy this item from the seller if you are the winning bidder. You will enter a binding contract.
By clicking Confirm bid, you are committing to buy this item from the seller if you are the winning bidder and have read and agree to the Global Postage Programme terms and conditions - opens in a new window or tab. Import charges previously quoted are subject to change if you increase you maximum bid amount.
Cancel
Loading...
Resume bidding, if the page does not update immediately.
Place bid
Review and confirm your bid
Bid confirmation
d
h
m
s
day
hour
hours
Free P&P
See item description
(Approximately ##1##)
(Enter ##1## or more)
(Enter more than ##1##)
Your maximum bid:
Increase maximum bid
Place bid
Confirm bid
Increase maximum bid
Cancel
Change bid
Close
, you've been outbid. Don't let it get away - bid again.
, you're the highest bidder on this item. Hope you win it.
, you're the first bidder. Hope you win.
, you're currently the high bidder, but you're close to getting outbid.
, this auction is almost over and you're currently the high bidder.
, you're the high bidder, but the reserve price hasn't been met.
Please enter your bid again.
Please enter a valid number as the bid price.
Enter an amount that is equal or greater than the minimum bid required. This can be found under the bid entry box.
Maximum bids can't be lowered once they're submitted.
This seller requires the buyer to have a PayPal account to purchase this item. Get a PayPal account here .
Your bid is greater than or equal to the Buy it now price. We recommend you purchase this item via Buy it now. If you still wish to bid, you may do so below.
Time left:
Current bid:
(approximately ##1##)
Your maximum bid:
(approximately ##1##)
Increase your maximum bid:
By clicking 1 Click Bid, you are agreeing to buy this item from the seller if you're the winning bidder. Learn moreabout 1-click bid - opens in a new window or tab
day
hour
min
sec
days
hours
mins
secs
(approximately ##1##)
Winning bid:
Starting bid:
Close
Congratulations The auction has ended and you're the winner.
The auction has ended, but the reserve price was not met.
Sorry, the auction has ended and you were outbid.
Good news, you're the highest bidder.
Sorry, you've been outbid.
You're the highest bidder, but the reserve price has not been met.
Please enter a higher amount than the current bid.
Maximum bids cannot be lowered once submitted.
Please enter a valid number.