Hi guys...

I've got this set of Penta II's that we are going to clean up....

What dis-assembly do you suggest for inspection??  I've got the bases off....(pentagons)....should we remove the amps and inspect them??

THanks,

 

Since you have removed the bases you may as well strip out the amps and give them a good clean out. I would check the solder joints and have a feel of the wiring. If any of it has gone brittle it may be worth replacing.

 Hope this helps!

 Llewelyn

Thanks for the input... do the amps just pull out from there...or do you have to take another 5 nuts off??  Thanks again...

IIRC there are five threaded shafts around 5" long that you need to remove. I think they are allen wrench heads. If you have a look underneath its fairly simple to work out! 

Have you already removed the cloth covers?  Once you do you can see whether the foam around the midrange drivers has deteriorated.  That's likely you're primary concern before worrying about anything else.
 

Hi Austin...well i've already got the new foam surrounds off ebay..(goodhifi.com)....and we'll replace those if needed....just want to do a full cleaning, etc....thanks !!

Any further info is appreciated...

salut

i have 2 penta mk1's with foam rot - ialso purchased new rings from good hifi however the supplied rings seem to be too big, the inner edge would appear to need to fit a good half way down the cone and the ridge appears to not be in correct location - can you give details of your rings external , interanal , internal exterior ring and external of interior ring dimensions - as not sure if g/h supplied correct rings

tony s

Thanks for the info Stotty....i've just got the rings and have not tried to fit them yet......

I'll check on them and get back to you.....i'm concerned now !!

 

stotty1111:

salut

i have 2 penta mk1's with foam rot - ialso purchased new rings from good hifi however the supplied rings seem to be too big, the inner edge would appear to need to fit a good half way down the cone and the ridge appears to not be in correct location - can you give details of your rings external , interanal , internal exterior ring and external of interior ring dimensions - as not sure if g/h supplied correct rings

tony s

 Hey Tony, I've also found Myrko's (goodhifi) surrounds to be a tiny bit too big sometimes, but if they're very close they should still work.

Austin
 

Hi Austin - i take your point but the rings supplied to me are compared to the original penta units below

Outer diam                   penta 77.5   goodhifi  77.0

outer(inner) diam           penta  74.5  good hifi  67.5

inner(outer) diam           penta  58.0  good hifi  55.5

inner(inner) diam           penta 52.0   good hifi  46.0

the good hif rings have a flat aspect the penta has an angled one  -  I am worried the extra 3mm encroachment onto the cone will affect performance as will any stress/strain imposed by the flat ring being mounted at an angle  -  anyone out there with observations, comments etc.

There is another Ebay supplier, Germany/Austria based, more expensive, but the rings are similar to the penta dimensions however I am currently trying to ascertain whether flat or angled  -  these are suggested for repair of Grundig units. 

http://cgi.ebay.de/2-99-Sicken-foam-surrounds-sondermass-High-Quality-F88_W0QQitemZ180213512110QQihZ008QQcategoryZ141261QQcmdZViewItemQQ_trksidZp1742.m153.l1262

http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=110131651907&ssPageName=ADME:X:AAQ:DE:1123

As previously comments/advice would be most useful!

tony

Hi Tony;....thanks for your input here....

 Are you going to purchase these new ones from Germany???

I've got the GoodHifi ones...but haven't put them on yet??

 Let me know..

 k

Hi again Tony,

Usually for speakers about 7cm and smaller, the rings don't come in angled versions, as the extra bit of strain is very minimal.  At least in the US I only see angled rings sold for speakers larger than 7cm.

I would be surprised if the extra 3mm made an audible difference in sound.   Does the curved fold in the ring line up correctly around the cone?  Meaning is it centered over the opening around the cone?

Have not decided about the German jobs may just buy apair to try as I have 9 Good Hifi rings here at present!

Re the curved edge, the cone has a diam of 57mm the outer of the inner has a diam of 55mm and the inner ridge on the underside sits over the cone rim - this is somewhat tricky to explain but hope i have got there!

So i would say the ridge would not be classed as centred over the gap between the fixed structural rim and the floating cone rim.

Tony S - UK

Hey all,

 I used the goodhifi surrounds and am pleased with the result!  I had a difficult time trying to fiqure out how to get the inside diameter to "stick and stay" down while the glue dried.  I emailed the seller and he was terrific!  He told me to use a correct sized tumbler from the kitchen, and position it "just so" till the glue dried.  Worked like a charm.  My pentas are all done now, and I hope they will last another 15 years!

 Guy

Thanks Guy....i've got the GoodHifi rings for a set of pentas..... Can you please tell me what glue you used??

Even a short "play by play" would be fantastic if you have the time..!!

Thanks a ton!!

Keith

Frank Rizzo:

Thanks Guy....i've got the GoodHifi rings for a set of pentas..... Can you please tell me what glue you used??

Even a short "play by play" would be fantastic if you have the time..!!

Thanks a ton!!

Keith

Keith I don't have time right now to type it out, but can in a couple days if you have time.  The best glue I've tried is "tacky" glue, found at arts and crafts stores.  It's similar to normal white glue, but remains slightly soft after it dries.  It's used often for speaker surrounds, and when the foam surround sellers offer you a special glue in an unmarked bottle, it's often just tacky glue.

Gracias..(thanks>>)....whenever you have time....we would all appreciate your experience...thanks...

 

keith

Subsequent to the input in this item I have ploughed on with the refurb using the GoodHifi rings - seems to have worked ok - one suggestion though if black based tacky glue could be obtained I would suggest using it - maybe I'm too particular but the white rather detracts! also, using alcohol to clean off surplus glue should be used sparingly the rings tend to expand and distort slightly - this caused me some probs - not too serious the rings regain original form when alcohol has evaporated.

Sound quality appears to be the same although I'm no afficianado - my ears have seen better days!');" title="Big Smile - ">

tony s

Hi Tony....I really appreciate the input....did you take pics???  We are just going to begin on this next week...

Also, can you (or anyone) list a black glue that they like to do this?????? Name, part number, etc.......

Thanks again guys.>!!!

unfortunately not taken pics never thought to do so sorry - do not know of any black glues i used stuff supplied by good hifi - after thoughts are always good! know what i mean!

tony s

Hi Tony...

GoodHiFi...did not send me any glue.....!!!

Can you please give me the name off the bottle???

Or if ayone else knows...

Thanks....

Do I need shims...for the midrange re-foam.....???

Or do i just use the rings from good hifi...and glue and a kitchen glass trick??

THanks,

k

i just used glue and glasses and/or the base of aerosol cans of appropriate size the inner was a little troublesome as weight diam needs to be just a little larger than the inner ring edge to ensure it seals down properly

good luck

tony s

Thanks Tony..

 So NO SHIMS needed??? yes...

Could you give me the brand, name and model of the glue??

Thanks again...keith

no details on bottle however pm your address etc and i'll send on the extra i have - g/h supplied two bottles only used about 3/4 of a bottle - its white however!

tony s