Comparing QSI High Bass Speakers With The Large Oval Speakers

by Don Fiehmann with Jim Betz

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SP installed both a steam and air horn on some of the Daylight and Cab forward locomotives. The SoundTraxx Tsunami has both of these available on their model 826103 decoder. Function key F3 that is normally used for a short whistle blast is used to switch between the two horns. The problem with these two types of horns is they have a lot of low frequency sounds components that are hard to reproduce with small speakers. I had already installed two of the large oval speakers in one of my brass Daylight (GS4) tenders and the horn sounds were satisfactory. I had a second brass Daylight (GS2) with the same size tender that also needed a Tsunami and speakers installed. For the GS2 tender the new high bass speakers were now available. There was also room for two of these in the tender.

Jim Betz was also converting a brass Daylight to DCC and needed to select speakers. He was interested in making a comparison of the two types of speakers to determine which would sound the best. Jim did the install of two high bass speaker to the floor of my Daylight tender the same way the large oval speaker were installed in the other tender. One of the differences between the two types of speaker is the way they are mounted. The large oval speakers have four mounting holes, one in each corner of the speaker.

The high bass is round and has no provisions for mounting. Jim used, Elmer’s-Tack to hold the speaker to the tender floor. This adhesive putty material comes in a package that looks like it could be clay and is available at craft stores like Michael’s. There are other similar products available like Stik-Tac, available at Tony's. This is not the tacky glue. The tack can be rolled up to make a thin “rope” that can be placed around the speaker in place. The material has enough sticky to hold the speaker to the tender. There were a couple of places where the holes in the tender were too close to the edge of the speaker. The tack was used to plug these possible air leaks. Also four pieces of the tack put around the speaker that were large enough to go between the tender floor and the upper part of the rim of the speaker to secure the speaker to the tender floor. The tenders were used as baffles for the speakers. (The “Tac” material is also good to hold decoders in place.)

A three wire Miniatronics connector was used to connect the tender frame and two speaker wires to the engine. Since both tenders had the same three wire connection, they could be switch back and forth between the same decoder. This would eliminate any differences in sounds due to decoder settings. Two Brass Daylight Tenders GS2 in front and GS4 in back.

The first test showed a remarkable difference in the quality of sound between the two. It reminded me of my experiences in hi-fi where the best way to improve a sound of system was to buy better speakers. The sound from the large oval speakers was good, just that the high bass speakers were better. Normally the better sounding speakers were lower in efficiency and required a higher amount of power to drive them to the same volume level. To check the sound level I used a Radio Shack DB meter placed at 8 inches from the side of the tender. The tests were done without making any decoder changes to the Tsunami other than the address and the dual horn option.

Test Sound	Large Oval Speakers	High Bass Speakers
Steam Whistle (F2)	83dB	82dB
Air Horn (F2)	82dB	87dB
Bell (F1)	75dB	75dB
Chuff (Speed 10)	84dB	85dB
Steam Release (F4)	82dB	81dB
Tender Water Fill (F9)	67dB	68dB
Dynamo (F0)	67dB	62dB

This test shows the ability of the speakers to convert the energy from the decoder to sound. What it does not show is the difference in the quality of the sound. Jim and I both agreed that the sound from the High Bass speaker was superior to the Large Oval speakers. Best described, like a commercial for coffee, it had a more full body and richer sound than the other speakers. The only big difference (5db) was the air horn. I attribute this to the greater amount of bass produced by the high bass speakers. The air horn has a low moaning sound. I listened to a disk from Pentrex that had the Daylight and both the horn and whistle on it. The sounds from the high bass speakers closely matched those on the disk.

Conclusion

As the small size speakers get smaller to fit into things laptop computers and plug in iPod devices, we will have more of choice in speaker size and quality. For now the High Bass Speakers seem to be the best you can get for locomotive speakers. They come in a variety of sizes to fit different scales and locomotives.