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Exposure IV power amp : any thoughts ?

Discussion in 'audio' started by Gervais Cote, Aug 4, 2020.

  1. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Whilst I've not had a IV and VIII at the same time, to put next to each other with lids off to make an exact comparison, it appears that they use the same boards and all that differs is the size of the PSU's... as in various Naim amps.
    Gervais Cote likes this.
  2. Luca

    Luca pfm Member

    Yes, you are right. I experienced that an huge sized power supply produces a fuller and deeper bass. I like it but not beyond the limit of redundancy.
  3. Conster

    Conster pfm Member

    The Exposure 1V is a cracking amp. Big bold sound that can drive most inefficient speakers however if the power isn't need I found the 18 or 18 super or monos to be quite excellent for less money. I found the 1VDR works best when it's power is needed
    Luca likes this.
  4. Luca

    Luca pfm Member

    Hi Conster, yup, the Exposure IV is cracking but I chose 8 and 18 because that big bold sound is too enphatic IMHO.
  5. Gervais Cote

    Gervais Cote Predator

    Here is an update to whom it might be of interest :
    It’s been a long process as the seller was a bit confused about the model, year and also the PayPal payment but I finally got my amplifier and listened to it this weekend.
    It seems to be from 1976, it’s a Dual IV mk2 (two transfo) and it seems to be a non regulated version as there are only two main boards inside and two small speaker protection boards attached to the binding posts. It also has two 2200 uf capacitors to feed a preamp.
    Most of the components including the reservoir capacitors are original, only a few ones seem to be newer so a recap has to be done soon. The transformers in this amp are huge !
    All I can say is that it sounds fantastic. Deep and very well non exaggerated bass, a midrange just a bit laidback with wide soundstage and a very smooth but detailed treble. Quite honestly, I was not expecting this old amp to be that good and as a rock and jazz listener, I’m not sure I can ask for more.
    I don’t want to push it hard given its age but I’m wandering is it will become meatier when recapped ?
    My Naim amps sound congested, two dimensional and harsh in the upper frequencies in comparison but I don’t want to start another debate here again...........
    So again thanks to all of you for your recommendations and inputs, always very appreciated.
  6. pil

    pil pfm Member

    What’s a decent pre to use with the IV?
    I have a curved type purple one,extremely tatty and down on one channel.
    Probably should get it fixed some time
  7. pocketkitchen

    pocketkitchen Registered User

    I found a vii and vi worked best. I also tried the xi and xii and whilst they were supposed to be better, the sense of drive was noticeably better with the earlier units.
    pil likes this.
  8. Gervais Cote

    Gervais Cote Predator

    I'm using a XXI to feed my IV and it sounds very lively and musical to me.
    I also tried a XXIII but found it a little too quiet although more detailed and accurate.
    Never tried anything else.
    mbu and pil like this.
  9. Yomanze

    Yomanze pfm Member

    If you are talking about the III, maybe one of the cards has come loose. Try opening it up and seeing if this is the case.
    pil likes this.
  10. pil

    pil pfm Member

    One thing I don’t understand is mine has 2 green lights to the left of the power button. Can’t see this on any in Google images
  11. Mike1965

    Mike1965 pfm Member

    Is that because it is the dual power supply version, one led for each?
  12. pil

    pil pfm Member

    Sorry only just seen this.

    ill try and post a couple of pics up this week
    Mike1965 likes this.
  13. pil

    pil pfm Member

    Bit late with the pics
    Label inside says from 1978
  14. pil

    pil pfm Member

    Struggling to post pics
  15. pil

    pil pfm Member

  16. cj66

    cj66 pfm Member

    All the versions of the IV were very capable, the dual and the dual regulated being the best.
    We used to partner them with mainly faster, less wallowy speakers and the balance was superb.
    e.g. Gale 301
    Naim SBLs
    Proac of the day, Minitowers were well suited and IVdr could even coax the Super Towers & EBS into action.

    I personally ran a single IVdr with Gale 302s and then x2 actively into SBLs, loved it!
    Last edited: May 21, 2023
    Gervais Cote likes this.
  17. cj66

    cj66 pfm Member

    On the IV front panel?
  18. Gervais Cote

    Gervais Cote Predator

    Here is a first picture of the amplifier :

    pil likes this.
  19. Gervais Cote

    Gervais Cote Predator

    And here is the power switch :

    pil likes this.
  20. Ben&Ted

    Ben&Ted pfm Member

    THe amplifier boards are different.
    The one on the left in the pic I have seen before in an early IV that I have had in the past.
    The one on the right I have not seen before, it may be a very, very early board or something else, not sure.
    As there are different boards there must have been a failure of a board necessitiating work to be carried out.
    The green LED's on the front I have never seen before and may have some connection to the work carried out and the different amplifier boards.

    This is a single IV unregulated with psu (for pre amp +24v-24v)
    pil likes this.

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