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View Full Version : Desparately need help with JBL HP 420



audio5
08-29-2008, 05:58 PM
Hi JBL folks:)

I have just acquired a pair of JBL HP 420 for $200 locally from another audiophile. I know I paid more than what they worth since with Orion Blue Book Value these guys are worth probably somewhere less than $60 but they are JBL so....:)

I brought them home give them a listen and then did the A/B comparison with my bookshelf Dynaudio DM 2/10. To my surprise the bass of the JBL was not that deep and tight as I expected even they are floorstanders. Compared to my cheap Dynaudio DM 2/10, they are just one or two level lower than the Dyns which has something to do with the cheap stock xover network and drivers I guess????

I tried walking the speakers. I tried adjusting the crossover dial on the speakers. I changed the speaker wire and what have you to no avail. Please note I used the very same NAD C372 integrated amp to do the A/B testing and I think the NAD gives the JBL enough power to sing. Yet either the bass is really boomy or it feels like no bass at all despite the fact listed in the technical sheet that the HP 420 can reach the 40 cycles (40Hz). I am in a dilemma:banghead:

I figure with the stamped drivers and the cheap crossovers that they used (to cut cost) it is time to service such components. But the cabinet is just like that of the L26 or L100, built to last (built in Denmark), almost in minty condition.

This is what I am thinking to do. The 026TI tweeters are surprisingly still pretty smooth compared to other metal dome tweeters so I will keep them. I plan to replace the original midrange 405G and original woofer 506G with maybe something from Scanspeak/Peerless??? Or is it better to upgrade the crossover network.

I never mess around with driver replacement before (zero experience). However, I wonder if I could disassemble the speakers (I got the technical sheets from JBL website) and replace the speakers with something different (non JBL stock drivers/woofers)

Greatly appreciate any feedback, concern, and input.

KR
PS I mostly listen to rock, vocal, hip hop, and some classical in this respective order.

I have listened to Totem Mani 2. I owned Totem Rainmakers and Dynaudio Audience 52 and DM 2/10 so I think I could tell whether bass could go to the low 40 cycle or not.

Thank you, thank you

Fred Sanford
08-29-2008, 07:57 PM
Most of what I know about these speakers is here in this thread:

http://www.audioheritage.org/vbulletin/showthread.php?t=19706

My first move on mine would be to replace the mid with something that does a better job of the low mids (but there's very little room to expand, width or depth, with the doghouse). I'll probably never touch them. They're a different sound from all my other JBLs, but they're interesting.

I paid about $40 for mine, one replaced glass top and one broken input terminal.

je

speakerdave
08-29-2008, 08:29 PM
. . . . I figure with the stamped drivers and the cheap crossovers that they used (to cut cost) . . . .

Well, I think you've only partially defined the problem.

It seems to me you have taken a sideways step by purchasing another set of speakers targeted at the same price point as the speakers you already own. So, they are no more satisfying than the ones you have.

Not everything labeled JBL is worth restoring, repairing, or even having. Unfortunately JBL, under the aegis of its parent company Harman International has joined the coterie of corporations that have purchased quality brand names and devalued them by manufacturing and selling down market products under that name. What we are about here at this website, is respecting and trying to preserve the quality heritage upon which the high regard for the brand was (and still is) based. While the speaker you describe is a perfectly acceptable product at its price point, I do not think it will add much esteem to the marquee.

If you were overcharged for the speakers, I think you should go back to the seller, tell him how you feel, and see what he is willing to do to improve the result for both of you.

Unless you really know something about designing speaker systems (apparently you do not), the probable result of purchasing new drive units and trying to build a crossover for them will be further disappointment and further financial loss.

You will very likely have better luck if you do one of the following: 1) buy quality used speakers at a reasonable price; to do this you must be familiar with the speakers and the markets. 2) build a kit, that is, a completely engineered system with matched components and crossover. Or, 3) study the current offerings, evaluate and carefully select a higher quality new speaker. Madisound is one source of kits, but there are many others. It is very unlikely you can build a better speaker for less.

David

audio5
08-30-2008, 07:43 PM
I want to thank both David and Fred.

I have always been a great fan of JBL until this corp was bought out by HKI.

I got this pair of HP 420 from a gentleman who sells things on Ebay for a living, thinking that I can do something as simple as I could do for my Dynaudio speakers, buying new drivers and replacing the old ones by myself. I am afraid that I can't return the JBL since I have removed the original glass tops already...ouch:banghead:

I am thinking about bringing them to Orange County speaker repairs for a free estimate to see how much they would charge me with xover upgrade and replacing drivers for the HP420. If they charge me less than $200, I will pay them to do so. I will keep them in my other room as part of my JBL collection. The real wood veneer cabinets built in Denmark are beautiful though :)

If you two are into 2 way speakers, check out the Dynaudio DM 2/10. I bought them brand new for my girlfriend and she loves them.

They are simple two way speakers that sport 1.25 inch silk tweeters and 10 woofers. But they are fun speakers to have. For the first time since I parted with my old JBL two way, I have found something that could engage me in audio again. They look like the L26 in the 70s only narrower and deeper in dimensions. I have them on a pair of Sound Anchor 22 inch four posts and they look very cool.

Thank you both kind sirs.

audio5
09-03-2008, 01:45 AM
Hello David,

It's me again sir.

I have checked with a gentleman at Madisound and he's said that it would be very, very expensive to restore my JBL HP 420 due to its complex crossover. He has also explained to me that the design on the JBL HP 420 is not push and pull like the JBL designed for the European markets (like the Totem Mani 2 or Linn Isobarik) so he politely told that it would be cheaper for me to buy new speakers as you suggested.

My NAD/Dynaudio used to sell JBL speakers but they both suggested me not to buy JBL speakers but go with either Dynaudio or PSB when I asked them about JBL speakers.

I called a local retailer of Scan Speak in Los Angeles and ask them for an affordable kit that would cost less than $1000, approach # 2. I spoke to a gentleman who worked there and he told me a 2 way kit that sports 1 inch dome tweeter and 1 7 inch paper woofer from Usher (a Taiwanese company) would cost me $800 and I could upgrade the drivers from Usher to Scan Speak Classic if I were to pay him another $600.

Do you think this is a fair price for an Usher DIY kit ($800) David?

Kindly note I could get another pair of Dynaudio DM 2/10 for approx $1,100 (brand new) or a Dynaudio Focus 140 around $1,100.

I will continue my search for a pair of L100 with a budget less than $150.

Man, I thought I got a reasonable deal on Craiglist but there are just too many unscrupulous people out there in the vintage JBL market:banghead:

Thank you sir,

Fred Sanford
09-03-2008, 05:33 AM
Hello David,

It's me again sir.

I have checked with a gentleman at Madisound and he's said that it would be very, very expensive to restore my JBL HP 420 due to its complex crossover. He has also explained to me that the design on the JBL HP 420 is not push and pull like the JBL designed for the European markets (like the Totem Mani 2 or Linn Isobarik) so he politely told that it would be cheaper for me to buy new speakers as you suggested.

I will continue my search for a pair of L100 with a budget less than $150.

Man, I thought I got a reasonable deal on Craiglist but there are just too many unscrupulous people out there in the vintage JBL market:banghead:

Thank you sir,

The twin woofers in the HP420s are push-pull, check the white paper you've downloaded (diagram below, showing two woofers face to face & out of phase).

The L100 is a VERY different sound from the HP420, in every way. If you're going that direction, I'd recommend the L110 or variants of that design, but your budget's going to be tough to hit without a lot of patience or luck.

I'm not sure how you're considering the Craigslist seller to be unscrupulous- they set a price, and you paid it first and did research later. Others have paid that price for the HP series and were happy with it.

Good luck to you, whatever path you choose.

je

speakerdave
09-03-2008, 09:42 AM
You seem to be bouncing from pillar to post.

Why consider $800 or $1100 for Usher kit or Dynaudio speaker and allow only $150 for used JBL? Oh . . . credit card . . . nevermind.

Madison has the parts only Scanspeak premium Solist kit for $1150/pair.


. . . . I tried walking the speakers . . . .

I don't understand.


. . . .This is what I am thinking to do. The 026TI tweeters are surprisingly still pretty smooth compared to other metal dome tweeters so I will keep them. I plan to replace the original midrange 405G and original woofer 506G with maybe something from Scanspeak/Peerless??? Or is it better to upgrade the crossover network . . . .

I suggest you make sure all of your drivers are original, working, and properly installed and use the speakers the way they are until you have recovered enough financially and emotionally (?) from this setback experience to proceed rationally.

Mr. Widget
09-03-2008, 10:11 AM
Man, I thought I got a reasonable deal on Craiglist but there are just too many unscrupulous people out there in the vintage JBL market:banghead:Maybe.

It could also be ignorance. JBL has made a lot of money selling largish cheap plastic clad boxes that weren't particularly good to people who simply don't know better. Unfortunately for them some people like yourself actually listen to them and then find themselves rather disappointed.

Good luck on your quest.


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