Dusty, please compare your pre-amps

JLM · « **on:** 13 Jan 2007, 11:43 am »

Introduction for everyone:

Although it's rarely been included, Dusty now offers three (maybe four?) pre-amps, the new PLC-1, the semi-new VPC-2, the brand new VPC-3, and the Monolithic Sound passive/active PA-1.

Dusty,

Couldn't find the price for the VPC-2.

Please provide details of the VPC-3.

Please compare the potentiometers and sound from all four.

Could I custom order a VPC-2, VPC-3, or PA-1 with the PLC-1's upgraded potentiometer? (Don't know if this applies now with the VPC-3.)

Would there be any sound degradation using the PA-1 without the HC-1b power supply if I keep the volume below 12:00? (I currently have a 2 volt RMS source and with my VMB-1's definitely don't need the extra gain, but never know what the future might hold so the slight additional cost could be worth it just to keep the options open.)

BTW, in a previous thread you mentioned preferring this type of passive pre-amp to transformer based. Could you please elaborate?

Thanks bunches.

CIAudio · « **Reply #1 on:** 13 Jan 2007, 05:59 pm »

We just returned from the CES in Las Vegas and haven't updated our website to include the new products...I hope to have this done by the end of the week.

The VPC-2 has been replaced with VPC-3. The new model uses a better Alps Blue Velvet potentiometer, gold-plated circuit board and silver solder construction. Price remains $299.

The Monolithic PA-1 uses a custom Alps potentiometer where the raw signal is fed into the input, then paralleled with the active signal when the 12 o'clock position is reached on the control. Being that the input signal is fed directly into the pot AND the active gain stage, you cannot use it without the power supply even in passive mode because the un-powered gain stage affects the input impedance.

I prefer resistive based passives over transformer types for several reasons...
Transformer types have much more coloration due to the amount of wire and turns in the transformer...and also the magnetic field effects.
Volume setting is done by selecting different taps on the transformer, which means a switch with several pairs of contacts and selecting the output level in "steps". A good potentiometer offers infinitely variable adjustment and higher reliability (no multi-position switch).

JLM · « **Reply #2 on:** 14 Jan 2007, 10:03 am »

Thanks for the quick answers Dusty. Wifey is dragging me to America's winter vacation spot (Minnesota) for some boutque surgery at Mayo.

What I meant by the power supply being optional (for the Monolithic Sound PA-1) was the use of the "upgrade power supply", HC-1B. Just wanted to clarify in case others are reading this.

Looks like there may be a VPC-3 in my future.

CIAudio · « **Reply #3 on:** 14 Jan 2007, 03:47 pm »

Sorry to hear about the surgery...that's never fun.

The HC-1b is a nice upgrade if you listen past the 12 o'clock position (in gain mode).
It makes PA-1/PS-2 completely dual mono by using separate high current/low output impedance transformers. It also has an internal 115-230v switch and IEC input for use with your favorite power cord.

JLM · « **Reply #4 on:** 27 Feb 2007, 10:21 am »

Dusty,

After following 111 pages

of the TVC thread in the Audio Circle I appreciate very much your concise, simple answers.

BTW wifey's surgery went like clockwork, those folks at Mayo are very good. Thanks for your kind comments.

JLM · « **Reply #5 on:** 24 Mar 2007, 10:25 am »

Just received my VPC-3. I've been enjoying VMB-1 monoblocks for a year with my 88 dB/w/m single driver speakers in a 13 ft x 21 ft x 8 ft room, and of course have seen the pictures of all the CIA equipment, but was unprepared for how small and light it would be.

This thing is easily the most expensive piece per pound I've owned since buying phone cartridges.

Now I have a couple of questions:

1. Is there any break-in time to be expected? (It has no real sound that I can hear now.)

2. I normally don't listen at high spls so I'm running out of usable travel of the volume control by 9:00, is this typical? (I've tried two different CDP's one of which is rated at 2.0 volts RMS output, the other is a Ah! Njoe Tjoeb 4000 that can be adjusted between 0.7 and 5.0 volts RMS.)

CIAudio · « **Reply #6 on:** 24 Mar 2007, 02:53 pm »

Quote

1. Is there any break-in time to be expected? (It has no real sound that I can hear now.)

2. I normally don't listen at high spls so I'm running out of usable travel of the volume control by 9:00, is this typical? (I've tried two different CDP's one of which is rated at 2.0 volts RMS output, the other is a Ah! Njoe Tjoeb 4000 that can be adjusted between 0.7 and 5.0 volts RMS.)

Being passive, there us no real break-in, although sound will change slightly after some use.

VMB-1's only require about .6V to drive them to full power. When using a 2v source and efficient loudspeakers, not having full range of the volume control would be expected.

When using the Ah! adjusted to .7-1.0v, you will have more range on the control.

JLM · « **Reply #7 on:** 3 Apr 2007, 10:37 am »

I don't consider 88 dB/w/m more than just average efficiency (these are not typical extended range drivers), but the 0.6 volt specification to reach full volume from the VMB-1's explains the limited travel range of the volume control on the VPC-3.

I've also completed wiring my system with Element Cables. Their entry level stuff is based Jon Risch DIY recipes and represent good value. (BTW, I'm not a cable guy.) I even replaced the VMB-1 power cords with Red Storms, which seemed to add impact and frequency extension.

All CIA components are working like clockwork, but I have noticed after walking across the carpet that touching the pre-amp first usually results in a static discharge. I guess that without a grounding plug that is to be expected. So I try to remember to touch the CDP first, which eliminates the static.

Thanks again Dusty.