JBL System 205 (130A woofer 275 driver 5040 horn N600 crossover) custom cabs

[Lampcord]

Hello, I started a thread in the wrong forum, so I'm moving it over here. Looking for input on best low watt tube amps for these well deserving speakers. Currently using an original Sherwood S8000. It sounds real nice, but it has hum in the phono section. Its not horrible, but I can hear some buzzing after record quits. Also wondering if crossover should be looked at. speakerdave gave good advice on keeping it original. Crossovers look real clean inside.

[Mannermusic]

Hello, I started a thread in the wrong forum, so I'm moving it over here. Looking for input on best low watt tube amps for these well deserving speakers. Currently using an original Sherwood S8000. It sounds real nice, but it has hum in the phono section. Its not horrible, but I can hear some buzzing after record quits. Also wondering if crossover should be looked at. speakerdave gave good advice on keeping it original. Crossovers look real clean inside.

Might take a look at quicksilveraudio.com. They have a new integrated amp that looks . . . interesting! Mike Sanders has been doing tube design for decades - not far from you.

[Lampcord]

Might take a look at quicksilveraudio.com. They have a new integrated amp that looks . . . interesting! Mike Sanders has been doing tube design for decades - not far from you.


Thanks Mannermusic. I've read up on them. I was intrigued br their twin 18 watt monos called HORN. they are 1899.00 new and saw a set awhile back on ebay for 1250.00. could be a contender. I live near a place called upscale audio in Upland. They have a lot stuff I can't afford, but also some attainable pieces. good used and clearance prices. Would like some feedback from people who own 16 ohm speakers. These are rated at 35 watts. I'm open to solid state, but all the amps I've tried sound like crap compared to the Sherwood. I want to use that as a back up becuase I could dump money into maintaing it, but if I am going to do that anyway, I may as well get something special, but not too special! The guy I got the Sherwood from said Mac 240 is the ultimate in his opinion, but I'm not going to pay 3gs for it. 2250, maybe a hair more. Also hear a lot of good things about the dynaco st 35 and PAS 2 preamp. Fairly priced gear. I don't do DIY, so I'm curious about amps with auto bias like Prima Luna and
Mystre. Used Cary 20w 40 w AB push pull. I saw used for right around 2g. I would probably go with Fisher KX 200. but too many unknowns with old parts, especially on/off volume pots. If anyone has listened the JBL SA 600 and what is it like compared to tube amps and other comparable solid state amps of that era. Thank you very much for your input.

[speakerdave]

. . . . speakerdave gave good advice on keeping it original. Crossovers look real clean inside . . . .

Two things: As you know, I was referring to the N500, which is what you had said you had. That crossover is a special case because it was used with the JBL 150 woofers, and I've seen it sold for $1000/pair on eBay. The other things is, I thought it would be potted in wax, making working on it a real chore. Your N600 is probably also collectible in some people's estimation, but if it were me I'd definitely replace those capacitors, maybe even with with biased pairs twice the size, or have it done if you are not confident in that kind of work. For restoration to collectibility, keep the old caps.

[Lampcord]

Two things: As you know, I was referring to the N500, which is what you had said you had. That crossover is a special case because it was used with the JBL 150 woofers, and I've seen it sold for $1000/pair on eBay. The other things is, I thought it would be potted in wax, making working on it a real chore. Your N600 is probably also collectible in some people's estimation, but if it were me I'd definitely replace those capacitors, maybe even with with biased pairs twice the size, or have it done if you are not confident in that kind of work. For restoration to collectibility, keep the old caps.

Thanks Speakerdave. Do you know of a trustworthy tech in the L.A. or O.C. area?

[Lampcord]

Two things: As you know, I was referring to the N500, which is what you had said you had. That crossover is a special case because it was used with the JBL 150 woofers, and I've seen it sold for $1000/pair on eBay. The other things is, I thought it would be potted in wax, making working on it a real chore. Your N600 is probably also collectible in some people's estimation, but if it were me I'd definitely replace those capacitors, maybe even with with biased pairs twice the size, or have it done if you are not confident in that kind of work. For restoration to collectibility, keep the old caps.

Hi, Speakerdave, you recommend 2x the value of the original capacitors. What exactly would that do? Also from the photo, is all that black stuff meant to hold the capacitors in place, or is it the capacitors leaking?

[speakerdave]

That might be the wax I was expecting. I'm not sure I would dig into that crossover. Is there a tapped inductor in there? If not, it would be better to build some copies and keep the originals intact. Need to find the schematic. I thought I had it here the other day, but now I can't find it. Have you found it?

[speakerdave]

From the input plate photos online I'm guessing there is a tapped inductor. Down in the right hand corner of that last photo there seems to be a coil. How many wires are coming out of it? I can't tell you how to work on that crossover via remote. If it works, leave it the way it is for now. Maybe a member local to you will emerge to lend you a hand or suggest a tech.

[Lampcord]

That might be the wax I was expecting. I'm not sure I would dig into that crossover. Is there a tapped inductor in there? If not, it would be better to build some copies and keep the originals intact. Need to find the schematic. I thought I had it here the other day, but now I can't find it. Have you found it?

Haven't been able to find one anywhere. I thought if anyone has all the original material from a Metregon, they may have it among that material. I've looked all through the library material here on the site. I wouldn't be opposed to bypassing the crossover and just putting caps and resistors if needed in line on the wire to replicate to middle setting for the time being. Also wondered if I should upgrade the 16AGW "Lampcord" used as internal wire, and recommended wire from speaker to amp. Thanks in advance.

[Lampcord]

From the input plate photos online I'm guessing there is a tapped inductor. Down in the right hand corner of that last photo there seems to be a coil. How many wires are coming out of it? I can't tell you how to work on that crossover via remote. If it works, leave it the way it is for now. Maybe a member local to you will emerge to lend you a hand or suggest a tech.

Hi, do you think it is much different than the N1200 schematic. I'm just guessing, but it seems the only difference would be the cutoff at 1200 cps vs
600 cps and 400 cps for the N400. Thanks again.

[speakerdave]

I think frequency division/response compensation networks embody a great deal of technically informed specificity, even in the wild west days of the N600, and understanding them is a prerequisite to working on them. Ergo, the advisable thing to do, is to have a tech update those capacitors, if that is your desire.

[Lampcord]

[QUOTE=speakerdave;411675]I think frequency division/response compensation networks embody a great deal of technically informed specificity, even in the wild west days of the N600, and understanding them is a prerequisite to working on them. Ergo, the advisable thing to do, is to have a tech update those capacitors, if that is your desire.[/QUOTE

Thanks for your input. I found photos of a N1200 rebuild. those two things in the black wax are coils. The capacitors are in the rectangular metal box behind them. 3 of them.

[speakerdave]

Well, it seems you are enjoying this adventure; that's the point, after all.

[Lampcord]

Well, it seems you are enjoying this adventure; that's the point, after all.

If the schematic you thought you saw turns up, I would sure appreciate an image of it. Thanks again!

[Oldmics]

In one of my old JBL Service manuals is the schemetic for an LX5 - Listed as used in the Metragon with the 2215 (16OHM) woofers

If interested I could post it up.

Oldmics

[Lampcord]

In one of my old JBL Service manuals is the schemetic for an LX5 - Listed as used in the Metregon with the 2215 (16OHM) woofers

If interested I could post it up.

Oldmics

Thanks for checking in Oldmics. The LX5 is for the C51 Apollo that has the LE85 driver. I don't know the cps cutoff on that driver. The 275 driver has a cps cutoff of 600. The age seems to be the right era.

[Lampcord]

Thanks for checking in Oldmics. The LX5 is for the C51 Apollo that has the LE85 driver. I don't know the cps cutoff on that driver. The 275 driver has a cps cutoff of 600. The age seems to be the right era.

Oldmics, please go ahead and post the image of the LX5. I just looked it up in the library and it shows it having a cps cutoff of 500, only 100 difference than mine. I'd like to look at it. Thanks for your help.

[Oldmics]

As requested

Oldmics

[Lampcord]

As requested

Oldmics

Does that manual mention system 205 anywhere? Thanks for LX5 schematic!

[Oldmics]

That Service Manual that I acquired the picture from does not mention the 205 system.

It mentions the use of these systems in the Metragon.

201

202

230

S82

S92

That being said I do have another manual (unfortunatly NO N600 schemetic) that does mention the 205 system.

Apparently the 205 system was the early used version for the Metragon 2 way system. It used (as you already know) the N 600 crossovers.

Those N 600 crossovers were only used for the Metragon-2 way 275 driver. No other cabinet got those N 600 crossover units.

I would have to say that my Service Binder is from a later period of time and that is why the N 600 is not mentioned. Sorry :(

You could contact JBL and see if someone there has the N 600 schemetic. I would guess that it is a bit different than the LX-5.

Why not just pull out the old caps and measure them to see what the values are and then replace them with newer caps.

A heat gun and a solder station and your in business.

Oldmics

[Lampcord]

That Service Manual that I acquired the picture from does not mention the 205 system.

It mentions the use of these systems in the Metragon.

201

202

230

S82

S92

That being said I do have another manual (unfortunatly NO N600 schemetic) that does mention the 205 system.

Apparently the 205 system was the early used version for the Metragon 2 way system. It used (as you already know) the N 600 crossovers.

Those N 600 crossovers were only used for the Metragon-2 way 275 driver. No other cabinet got those N 600 crossover units.

I would have to say that my Service Binder is from a later period of time and that is why the N 600 is not mentioned. Sorry :(

You could contact JBL and see if someone there has the N 600 schemetic. I would guess that it is a bit different than the LX-5.

Why not just pull out the old caps and measure them to see what the values are and then replace them with newer caps.

A heat gun and a solder station and your in business.

Oldmics

True. There's a guy on ebay in LA area trying to sell a metregon cab for close to $3000.00 Way too much. The most I've actually seen one sell for was around 5500.00. If I could find one in good shape for 1500.00 to 2000.00 I jump on it. Its wierd becuase tje original owners I got these from never had a Metregon. The man who had passed, was an engineer for Boeing. He just bought the parts and had the cabinets made.

[Oldmics]

P.M. sent

Oldmics