Official Ampeg Portaflex Club

[Hoochie Coochie Man]

Mesa Diesel 115 and 215 cabs were also based on the TL606. It’s a good design. Many other builders do TL-606 based cabs.

The KappaPro 15A in the PF-115 LF is a good choice. I don’t much like LF speakers.

I’ve always gravitated towards cabs with 15” speakers. Maybe because that’s what I used in the early years when I started.



View attachment 7033755

I own two Mesa Road Ready Diesel 115 TL606 cabinets, and two of the Ampeg B15 Thiel cabs.

I measured the internal dimensions of the first Mesa cab when I acquired it, and it is identical to the original drawings published by EV within a 16th of an inch.

I could be wrong about this, ( as I often am), but I think that the Ampeg ones I have do not conform exactly to the original EV drawings.

Here is a photo I found on the web of the Mesa version which is identical to the ones I have.

I know I have photos of my Ampeg B15-EV Thiel cabinets which I wanted to post here, but I can't find any right now.

I really dig Mesa's version of the EV design.

The Mesa trak-lock casters, and the cabinet as road case look cool as heck, even though I don't haul them around anywhere, (my Subway Ultralight 115 is much easier, and more capable).

I was using the amp from my (rare? only 700 made?) 1967 50 watt B12-XTC, (4-12 Jensen) guitar/accordion amp on the first Mesa Diesel cabinet for a while and I could not bear to look at it with the Mesa badge on it, so I removed it. (@agedhorse may be glad to know, that I have since reattached the Mesa badge to that cabinet).

 

[beans-on-toast]

Might have to give that a try.
Right now I’m cycling through all my basses to see which ones play best with the 1966 B-18. This one is a match made in heaven…
View attachment 7034824
It’s a 1966 Tbird NonReverse Tribute I built a few months back. Mahogany body painted in Golden Mist Poly (same color as Fender Shoreline Gold metallic), with a wenge/wenge neck and Epiphone 760 ProBucker pickups (fairly true to the original Tbird pickups). Sounds fantastic through the portaflex.

Gorgeous bass and work!

 

[beans-on-toast]

I own two Mesa Road Ready Diesel 115 TL606 cabinets, and two of the Ampeg B15 Thiel cabs.

I measured the internal dimensions of the first Mesa cab when I acquired it, and it is identical to the original drawings published by EV within a 16th of an inch.

I could be wrong about this, ( as I often am), but I think that the Ampeg ones I have do not conform exactly to the original EV drawings.

Here is a photo I found on the web of the Mesa version which is identical to the ones I have.

I know I have photos of my Ampeg B15-EV Thiel cabinets which I wanted to post here, but I can't find any right now.

I really dig Mesa's version of the EV design.

The Mesa trak-lock casters, and the cabinet as road case look cool as heck, even though I don't haul them around anywhere, (my Subway Ultralight 115 is much easier, and more capable).View attachment 7034857

I was using the amp from my (rare) 1967 50 watt B12-XTC guitar/accordion amp on the first Mesa Diesel cabinet for a while and I could not bear to look at it with the Mesa badge on it, so I removed it. (agedhorse may be glad to know, that I have since reattached the Mesa badge to that cabinet).

I wouldn’t expect Ampeg to use the TL-606 dimensions, I’d think that it would have to be licensed. Ampeg first released their cab in late 1967 (I believe).

This spec sheet is interesting for EV’s TL606A. It uses the EVM15L II.

https://products.electrovoice.com/binary/TL606A_TL606D_Engineering_Data_Sheet.pdf

 

[Hoochie Coochie Man]

Mr. b-o-t.

I think that EV published the TL cabinet designs without restriction on it's use as a way to allow anyone to copy it so as to sell more drivers.

You may possibly clarify for me a statement in the EV design document concerning blocking off the center section of the shelf port that I am not really clear about.

What I don't understand is the reference to the "step down EQ". If you put the block in the center section of the shelf port, is that also intended to be coupled with a different EQ curve on the amplifier output signal? Or, does it just alter the tuning of the cabinet without requiring a different input eq elsewhere in the signal chain? Does the reference to EQ only refer to the cabinet? Thanks.

I have a few variants of the EV 15-X driver. EV-15L. EV-15B. (Same driver, different cone/surround/spider?), and at least one EV15-X "Pro", (rated maybe over-optimistically at a greater power handling rating than the earlier non "Pro" version). I may have an EV15-X II around here somewhere as well. I think the Pro I have has some added heat-sinking material on the back of the magnet. I don't know if there are other differences in the design of the Pro version that you can't see, (like a different voice-coil, former, gap-etc).

 

[GBassNorth]

Try a JC.

That’s the plan for tomorrow. The Jack Casady pickup is much hotter than the ProBuckers in max choke mode, so might over drive the preamp a bit, but the center and low choke settings could sound very nice indeed.

 

[beans-on-toast]

Mr. b-o-t.

I think that EV published the TL cabinet designs without restriction on it's use as a way to allow anyone to copy it so as to sell more drivers.

You may possibly clarify for me a statement in the EV design document concerning blocking off the center section of the shelf port that I am not really clear about.

What I don't understand is the reference to the "step down EQ". If you put the block in the center section of the shelf port, is that also intended to be coupled with a different EQ curve on the amplifier output signal? Or, does it just alter the tuning of the cabinet without requiring a different input eq elsewhere in the signal chain? Does the reference to EQ only refer to the cabinet? Thanks.

I have a few variants of the EV 15-X driver. EV-15L. EV-15B. (Same driver, different cone/surround/spider?), and at least one EV15-X "Pro", (rated maybe over-optimistically at a greater power handling rating than the earlier non "Pro" version). I may have an EV15-X II around here somewhere as well. I think the Pro I have has some added heat-sinking material on the back of the magnet. I don't know if there are other differences in the design of the Pro version that you can't see, (like a different voice-coil, former, gap-etc).

The cover alters the tuning of the cabinet. See figure 10 from the pdf above. They say… “With appropriate electronic boost provided by an underdamped second-order high pass filter tuned to 45 Hz, an f3 of 40 Hz for both the TL606A and the TL606D.” If you add the port the low end extends but the rolloff is slow, it’s much improved with the sharper high pass filter. The required HPF is more than what you can get out of a typical EQ adjust. “The proper electronic boost for the TL606A and TL606D is provided in the Electro-Voice XEQ-1 electronic crossover. Also, proper electronic boost may be obtained by modifying the Electro-Voice SEQ equalizer. “. These are crossovers located at the amp’s output.

SEQ equalizer info: https://products.electrovoice.com/binary/Sentry III Series II EDS.pdf

There’s never a free lunch, everything has a consequence and you’d have to try it with the selected speaker and see how it sounds without the crossover EQ. It’s important to try it at different volume levels to ensure that the port air flows well in and out and without chuffing.

Ampeg experimented with plugging the B15N ports with foam, they also tried smaller sized ports. Jess disliked what it did and he soon had it back to normal.

 

[Stealth57]

So which will be the winner? Red, green and blue LEDs. 8 pack of each, so after picking a winner there will be left overs if anyone wants some.

 

[beans-on-toast]

So which will be the winner? Red, green and blue LEDs. 8 pack of each, so after picking a winner there will be left overs if anyone wants some.

View attachment 7035461

I’ve seen blue ones that looked cool.

 

[Lovep]

So which will be the winner? Red, green and blue LEDs. 8 pack of each, so after picking a winner there will be left overs if anyone wants some.

View attachment 7035461

BLUE!!

 

[deekay911]

I got my 1965 early SB12 out of storage since I recently sold the B15N. Plugged it in and it there is a fair amount of hum, proportional to volume. I am in the UK now, and using a stepdown transformer which is giving me 120VAC. The B15N always sounded great and super quiet even with the stepdown.
I decided to take a quick look around the circuit for any obvious causes. I hesitate to mess with the adjustable bias, but in any case measured the voltages at the OT center tap and 7868 plates. I got 446V at the OT and 441V at the plates. This is quite a bit higher than the 420V quoted on the inbuilt schematic. Is it because the input is 120 instead of 117? I wouldn't think that would make much of a difference. I measure the B, C and D voltages and these came out at 433V, 365V, and 295V respectively - again all quite a bit higher than the quoted figures. Any ideas on what would cause this and if it is a problem? cheers

 

[Hoochie Coochie Man]

Electro-Voice XEQ-1 electronic crossover

Thanks b-o-t. Now I see that the reference is to an electronic crossover that EV offered as a separate product:

https://mypicsonline.net/archive/archives.telex.com/archives/EV/Equalizers/EDS/XEQ-1%20EDS.pdf

 

[Hoochie Coochie Man]

I got my 1965 early SB12 out of storage since I recently sold the B15N. Plugged it in and it there is a fair amount of hum, proportional to volume. I am in the UK now, and using a stepdown transformer which is giving me 120VAC. The B15N always sounded great and super quiet even with the stepdown.
I decided to take a quick look around the circuit for any obvious causes. I hesitate to mess with the adjustable bias, but in any case measured the voltages at the OT center tap and 7868 plates. I got 446V at the OT and 441V at the plates. This is quite a bit higher than the 420V quoted on the inbuilt schematic. Is it because the input is 120 instead of 117? I wouldn't think that would make much of a difference. I measure the B, C and D voltages and these came out at 433V, 365V, and 295V respectively - again all quite a bit higher than the quoted figures. Any ideas on what would cause this and if it is a problem? cheers

I have two SB-12s, that are being supplied 120VAC, and they do not hum.

There may be other causes of the hum not related to the higher line voltages, but If the voltages are too high look into a "buck transformer", (which you may be able to cobble together yourself) that would provide a lower voltage.

Bucking Xfmrs

Bucking Transformers - What they do, how they do it, and how to determine the proper transformer to use

sound-au.com

 

[beans-on-toast]

I got my 1965 early SB12 out of storage since I recently sold the B15N. Plugged it in and it there is a fair amount of hum, proportional to volume. I am in the UK now, and using a stepdown transformer which is giving me 120VAC. The B15N always sounded great and super quiet even with the stepdown.
I decided to take a quick look around the circuit for any obvious causes. I hesitate to mess with the adjustable bias, but in any case measured the voltages at the OT center tap and 7868 plates. I got 446V at the OT and 441V at the plates. This is quite a bit higher than the 420V quoted on the inbuilt schematic. Is it because the input is 120 instead of 117? I wouldn't think that would make much of a difference. I measure the B, C and D voltages and these came out at 433V, 365V, and 295V respectively - again all quite a bit higher than the quoted figures. Any ideas on what would cause this and if it is a problem? cheers

120VAC vs 117VAC is well with the spec. The voltages are higher and it does stress the circuits but not beyond the working envelope. The higher voltages are below 10%. I wouldn’t assume that the line voltage is 120VAC. It should be measured with an AC voltmeter to confirm. Some areas that claim to be 120 are higher.

It’s important that the power tube bias be optimally set for the higher line voltage. Changing the bias will affect the plate voltage of the power tubes, it could come down. One concern of higher internal voltages is the power supply capacitor voltage ratings, especially the first capacitor (B+). It should have at least a 500V rating, higher is better.

As mentioned, a bucking transformer or a variac can lower the line voltage to 117.VAC. A good option.

 

[Kgold]

Yes, that’s a Cleveland. It was the most found 18” 8 ohm speaker that Ampeg used, so factory original. There was a British Goodmans 18” speaker in some amps for a short while.

Well, I’m just getting around to servicing my BT-18c. It’s been very hard to track down any information about it.
When I got it, one of the speakers wasn’t working and it looks like someone did a very poor diy job on the culprit. The spider is glued in a very crazy way - see pics. It turns out that the speakers are Goodman (I believe). I’m assuming they are original and I’d like to keep them with the amp. Does anyone know anyone who could recone something like this in the east coast? Im in CT. I’ve never had anything reconed before. Alternatively, could anyone send a link to a recone kit that would fit this beast? Also, is it strange that there is no cap over the magnet back?

Thanks for the help. It’s a very cool amp and I’ve enjoyed it even with one speaker !

 

[DJ Bebop]

I’ve seen blue ones that looked cool.

 

[Ringhammer]

I’d go green…

 

[beans-on-toast]

Well, I’m just getting around to servicing my BT-18c. It’s been very hard to track down any information about it.
When I got it, one of the speakers wasn’t working and it looks like someone did a very poor diy job on the culprit. The spider is glued in a very crazy way - see pics. It turns out that the speakers are Goodman (I believe). I’m assuming they are original and I’d like to keep them with the amp. Does anyone know anyone who could recone something like this in the east coast? Im in CT. I’ve never had anything reconed before. Alternatively, could anyone send a link to a recone kit that would fit this beast? Also, is it strange that there is no cap over the magnet back?

Thanks for the help. It’s a very cool amp and I’ve enjoyed it even with one speaker !

Possibly a Goodmans Audiom 91?

Goodmans 18" Audiom 91 Bass Speakers

Goodmans 18 inch Audiom 91 Bass speakers

www.voxac100.org.uk

I don’t know where you find a recone kit. A good reconer would be able to make one from scratch. I’d ask locally at amp repair shops as shipping such a heavy speaker would be expensive. If you change one speaker, it’s best to change the pair.

Make sure that the speaker needs to be reconed. Sometimes tinsel the lead from the speaker to the connector just needs to be carefully resoldered. If you gently push on the cone and hear a scratching sound it indicates that there a problem.

 

[Kgold]

Possibly a Goodmans Audiom 91?

Goodmans 18" Audiom 91 Bass Speakers

Goodmans 18 inch Audiom 91 Bass speakers

www.voxac100.org.uk

I don’t know where you find a recone kit. A good reconer would be able to make one from scratch. I’d ask locally at amp repair shops as shipping such a heavy speaker would be expensive. If you change one speaker, it’s best to change the pair.

Make sure that the speaker needs to be reconed. Sometimes tinsel the lead from the speaker to the connector just needs to be carefully resoldered. If you gently push on the cone and hear a scratching sound it indicates that there a problem.

Thanks! That’s gotta be it. Looks exactly like the audiom 91 except they are both missing the cap on the back for some reason. Do you think that will be a problem?
One of the speakers is definitely crunchy so I suppose I should recone both. Hopefully I can find someone locally. I think I heard that the guy at fliptops.net does reconing?

 

[beans-on-toast]

Thanks! That’s gotta be it. Looks exactly like the audiom 91 except they are both missing the cap on the back for some reason. Do you think that will be a problem?
One of the speakers is definitely crunchy so I suppose I should recone both. Hopefully I can find someone locally. I think I heard that the guy at fliptops.net does reconing?

The cover is cosmetic, nothing to worry about.

Have a local reconer check out the speaker. It may not need to be reconed.

 

[Stealth57]

LEDs installed. Which ones? Or stay with clear bulbs?