I have been breaking in the 41 HZ board for close to a week now. I have been feeding it a +10 dB signal from the Hagerman FryKleaner Pro. It has been hooked up to a pair of 250 watt 8 ohm load resistors. I have fed it a signal for 10-12 hours during the day and recharged the battery overnight.
The battery is a 5.0 Ah SLA. The same battery is used in the modded Tripath Eval board.
The 41 HZ board was built with pretty close to the stock parts supplied with it. The only diferences were I chose to jump out the connection for the input coupling caps and mount a pair of 3.3 uf Sonicaps off the board. The wire used to wind the torodials was a 99.9999% pure copper, solid core, cryo-treated 24 awg. The coils were measured and matched.
I also used a cap bank off the board of 4) 4700 uF low ESR caps between the battery and the board. Input connectors are WBT gold plated NextGen and output connectors are Eichmann Gold plated CablePods. Input and output signal wires on the 41 Hz boards is 99.9995% pure, solid core silver.
The Tripath Eval board also used the same Sonicaps. The onboard PS caps were upgraded to higher value and higher capacity versions. All wiring was done with my M-80 solid core wire. The stock input and output connectors were removed. Wiring was run from the circuit boards direct to the aftermarket connectors.. Input connectors are Cardas. Output connectors are Vampire.
Source used was a CAL Delta feeding a Mensa Plus DI/O. Pramp is my modded Hagerman Clarinet. Bolder digital cable from Delta, NITRO with Bybees from the DI/O to Clarinet. Summit interconnects from the preamp to the amps. Speaker cable is BOLDER M-80. Speakers used were Acoustic Reality 3D with Subs. These use ScanSpeak Revelator drivers.
The room is my office. Roughly 9' x 14' with a sloped ceiling from 14' to 8'. Eighth Nerve room treatments are used.
The gain on the amps is identical, so level matching was not a problem.
Quick down and dirty differences: the 41 hz amp had more extended and details high and lows. The Tripath board sounded a bit compressed and withdrawn.
I used Herbie Hancock's recording of Watermelon Man. At the beginning when the bass guitar comes in, the 41 HZ board had quite a bit more extension. I could feel the floor start to vibrate in responce. The tamborine had more body and I could hear the hand of the player hitting the skin more clearly. The bass had more definiton. I could easily hear the finger plucking.
With the Tripath Eval board, the bass was fairly muddy. It did not seem to go as deep or have the same impact. Highs were not as extended. It sounded like the top and bottom octaves were missing. Dynamics were limited in comparison to the 41 Hz board.
Next up was that favorite of the NY Rave: The Bad Plus: Keep The Bugs off Your Glass and the Bears Off Your Ass. Here the differences were more obvious. The upright bass had full body and extension with the 41 Hz. The plucking and finger movement were very clear. The lower ranges were presented with full weight, speed and tightness. The drum kit was hard in the center of the image. It was very easy to hear the differences of placement of the various drums that make up his kit. It spread across from left to right but did not wander around. The Piano also had good weight and fullness. The keys striking the wires could be heard clearly.
With the Tripath eval board everything was dull and boomy in comparison.
The low end extension was not even close to the 41 Hz. There was very little control of the woofers. Bass was very sloppy and it boomed. The image of the drum kit was not as defined. The lower notes of the piano also did not have the control of the 41 Hz.
The final comparison was with Richard Thopson's Mock Tudor album. I used Cooksferry Queen, Crawl Back (Under My Stone) and Uninhabited Man.
Pretty much the same differences came out between the two amps. The Tripath Eval was muddy and slow sounding in comparison. The low end extension simply was not there. On Uninhabited Man there is a very low bass that was completely missing with the Eval board. On Cooksferry Queen, Richard Thompson uses his very expressive voice to indicate some very subtle emotions. Again the subtlies were missing with the Eval. It was as if the speakers has a very thick blanket over them.
With the 41 Hz board, not only was the blanket removed but the top and bottom octaves showed up. I also noticed while listening to Crawl Back (Under My Stone) it seems that there was more silence between the notes. This is similar to the effect I have heard when Bybees are installed in a piece of gear, but not quite that dramatic. Richard Thompson's voice had far more emotion in it. I could easily hear his sneering throughout the song.
There were differences in the construction of the two amps that could influence the sound. The cap bank could add to the dynamics by lowering the ESR in the power supply. The Silver wire, though no longer than 3" in any one place, could have helped with the definition and high end extension. I feel that the biggest differences were due to the improved parts quality and layout of the 41 Hz board. The hand wound toroidals in the output filter, make up one of the biggest differences, IMHO. By using all metal film SMT resistors the signal might be able to pass through the board with fewer changes in the sonics.
The 41 hz board is no where near as easy to build an amp with as the Tripath eval board. There are many hours involved working with SMT parts. I do feel it is very much worth it. The sonic differences are quite apparent to my ears in my system.
I will continue to run the 41 Hz board on my break-in system for a few more days. I intend to ship it out to Ed Schilling of the Horn Shoppe for his get together next weekend. There will be a few folks there with other Tripath based amps and Ed's First Watt amp. It will be interesting to find out what they have to think of the amp.
I do intend to offer fully assembled amps based on the 41 Hz board. I will start assembling them next week. Price yet to be determined. It will be in the roughly $550-$750.00 range, depending on options and connectors.
I really do not suggest using the amps with a passive attenuator. I do feel they sound quite a bit better with a tube preamp in front of them. However, if a customer feels he must run passive, the 41 Hz board can be built with a bit more gain to make up for the passive attenuator. It can also be built with less gain if someone is using a preamp with excessive amounts of gain in it.
I do have the one amp left I built with the Tripath Eval board. It is available for sale. Please contact me about it if you are interested.
