Questions about the New Paramount 2A3 with Soft Start

[Frihed89]

I am new here, and considering buying the Paramount 2A3 amp kit.  I have looked for answers to my questions before posting and have found some information, here and on the Magnaquest site, but I still have some questions. 

1.  What are the 2A3 OPT options?
2.  What is the measured hum of the 2A3 amp?
3.  Can owners comment on the hum level?
4.  Are there any other "upgrades"/modifications for this amp, "official" or otherwise?
5.  If I have a deHavilland tube preamp with 8-10dB gain, will this work well with the Paramount?

Thanks very much for your help.

 

[Paul Joppa]

Frihed89, welcome to the forum  :^)

1.  What are the 2A3 OPT options?

The stock output transformer has a 3K primary impedance, with measured performance similar to the Magnequest upgrade, but the materials and workmanship are not as good. The output transformer BH-5 is a custom variant of the TFA-2004Jr design, also 3K ohms. I designed the stock unit, and consulted closely with Mike during the BH-5 development. I'll let other comment on any sonic differences. The Magnequest transformer is available with permalloy (50% nickel) laminations, which I prefer (especially with the 2A3) but not everyone agrees - there are a number of posts in the archives.

2.  What is the measured hum of the 2A3 amp?

With a good 2A3, something around 0.5mV should be obtained.

3.  Can owners comment on the hum level?

I'm sure someone will!

4.  Are there any other "upgrades"/modifications for this amp, "official" or otherwise?

The Magnequest iron is mentioned above. The Paramount package includes the BH-7 plate choke, which is sized for a 300B at 70mADC. If you know you will stay with a 2A3, then I would ask Mike for a BH-6 choke instead - it is sized for the lower current but gives you more inductance, always a good thing in a plate choke.

The parafeed capacitor is often replaced; we don't advocate any particular capacitor since there are so many options and almost everyone has a favorite. We supply a good quality Solen polypropylene; I have Auricaps in my personal amps. In 2A3 form, the amp is direct coupled so there are no other capacitors in the direct signal path.

The current Paramount version (1.1) incorporates the new, more rugged "soft-start" driver design with 5670/2C51/WE396A tubes. Gain is about 5dB less than the original which had 12AT7s.

5.  If I have a deHavilland tube preamp with 8-10dB gain, will this work well with the Paramount?

A preamp with 8-10dB gain will work well with Paramount; it is however more gain than you need. The sensitivity in 2A3 form is about 0.9vRMS for full output.

Well, that's a start!

 

[Doc B]

I am new here, and considering buying the Paramount 2A3 amp kit.  I have looked for answers to my questions before posting and have found some information, here and on the MagnaQuest site, but I still have some questions.  

1.  What are the 2A3 OPT options?
We offer a stock output transformer designed by Paul Joppa and manufactured by our winder on the West Coast. This uses a fairly innovative design with fairly standard materials. In the past MQ has offered transformers for the Paramount. These were co-designed by Paul Joppa and Mike LaFevre. The magnetic design is similar to stock and the materials are more exotic. Mike is the guy to talk to about these as I am not sure if they are presently in the lineup. Typically he offers varying amounts of Permalloy in with the steel lams. With the lower output level of a 2A3 you can probably get away with more Permalloy in the core than with a 300B. Mike will have estimated power levels for each core material.

In past kits I have found the MQ upgrade to be a profound improvement. In the case of the Paramount it is more of a flavor choice - The MQ iron has its signature liquid midrange and the Permalloy versions have amazing resolution, while the stock transformers are not too far off in these areas and may give the impression of a little bit more bass punch.

2.  What is the measured hum of the 2A3 amp?
3.  Can owners comment on the hum level?
This is going to vary with the tube, but in general we see well under 1mV of hum. I was auditioning 2A3s with Paramounts and headphones a couple of weeks ago to check the tubes for noise and I could not resolve any hum through them.

4.  Are there any other "upgrades"/modifications for this amp, "official" or otherwise?
We have a new version with a soft start that helps preserve the exotic EML tubes at startup. Others have upgraded to boutique style parallel feed output capacitors, usually Mundorf. I think that upgrading a bypass cap on the shunt regulator board might offer a tiny improvement. The biggest changes will be tubes and capacitors.

5.  If I have a deHavilland tube preamp with 8-10dB gain, will this work well with the Paramount?

Yes, in particular the current soft start version which has had its input sensitivity lowered from the original, which some users found a little too hot.

Thanks very much for your help.

Thanks for asking!

 

[Frihed89]

Thanks very much to the both of you for your quick and informative replies.  A  few more questions?

1.  OPT follow-up.  I looked at the Magnaquest page again and some posts on the forum about iron upgrades.  I am only looking at the 2A3 version of the Paramount at the moment.  Are we talking about the BH-5 OPT options with the BH-6 plate chokes (not the BH-7)? Are the prices listed on the Magnquest site, the upgrade price? Do the upgrade prices include the choke? Or, more simply, what are the upgrade costs of the Nickel Stripe and Full Nickle, including the choke, if its not stock?

Magnaquest makes the OPTs for Wavelength (or used to).  Have you heard of anyone asking them to make a silver OPT for any of your products?  Have you ever heard such an animal with the Paramount, or any of your products?  It certainly would not be cheap, but what do you "think" silver would (or does do) that nickel doesn't - good and bad?  I understand that Wavelength products are in a much higher price class.

I'm asking all these transformer questions, because my listening experience with another mfr's SET products (i own a 300B amp and a shop is located close to my house in Copenhagen) is that the quality of OPTs (and IC and Interstage transformers) make a very large sonic difference to me.  Are they worth it is NOT a question I am asking.

2.  Power Transformer.  You don't by any chance include a true 230/50 or dual voltage power transformer as an option?  If not, do you know if anyone has tried to source these from elsewhere and what the particulars are.  (The UK, so far as I know, is the last bastion of 240/50 in the EU).  Yes, I know actual "street current" fluctuates.

3.  Dimensions/weight of each Paramount mono?

4.  Where can I hear this amp?  Sold any in Denmark?  I also plan to be in the US some time in October-November to visit family, Bay Area , and Denver or Portland, OR (a workable drive to Seattle).

Thanks again...

 

[Frihed89]

I spotted this quote from "Sr. Management" while surfing today on the Paramour site: " The Paramount with 16 ohm output impedance will provide 2.5 watts into a 50 ohm load, and has DC heaters. It works well with the K-1000s, too."

I, too have a pair of LCD-2 headphones, so can you explain to me what OPT option for the 2A3 version of the Paramount has a 16 and 8 Ohm tap and how you connect that headphone load to the speaker terminals?  Or do you have a schematic for a headphone circuit?

Humm, on further reflection, that also means the amps have to be located close together to connect the headphone cables.

 

[Doc B]

OK, few different and interesting topics here -

Re the transformers - the way those work is that Mike's coil winder has to make a couple dozen coils of a particular model in one production run. So the wire choice requires a "manufacturing quantity" commitment, as they must all be done with the same wire and we might be talking a ten pound spool or more of silver wire. Mike has only done the Paramount upgrade transformers with copper wire as far as I know. On the positive side, the lamination choice can be done to order individually, so there is more flexibility there. I can't really speak too much about silver because I have always seemed to prefer a good quality copper wire. I think all of these flavor choices are influenced a great deal by the sonic character of the source. Just as an example I suspect the more mellow tone of copper might work better with a digital source and silver might work better with the more liquid sound of LP or tape. As for nickel, I also tend to differ from Gordon's taste here. He prefers the higher grade steel laminations like M4/M3, and I prefer Permalloy when it is possible to use it without the risk of oversaturating it. To my ears silver wire tends to emphasize the top end and maybe to some extent transient info. Nickel lams give a better sense of extension on both ends of the spectrum as well as increasing the overall resolution. This can have an effect of making the noise floor more audible and I think some people don't like it as much as a material that is less sensitive at low signal levels because the less sensitive material can give more of a sense of "black" between the notes.

The power transformer we supply (240V/50Hz) will give you the proper voltages at 230V, no problem. That's only a 4% variation, well within the acceptable range for filament voltage variation.

The amps are on a wood base that is about 24cm x 29cm and about 20-23cm tall depending upon the output tube that you use. Off the top of my head I think each monoblock is around 6 Kg.  (Total shipping weight is around 13Kg.)

Regarding hearing them - too bad my American cousin who has lived in Denmark for the past 25 years is not an audiophile. You would certainly be welcome to visit us in Seattle when you come to the West Coast, and I'm sure there are quite a few Paramounts in the Bay Area and probably some in Denver as well. Hopefully someone from one of those areas will see this and offer an audition.

RE headphones - I have not tried the LCD-2 with the Paramount yet, but hope to at a Head-Fi meeting at Bottleheadquarters in May. So far we have not heard the LCD-2s sound their best with our smaller dedicated headphone amps. I would probably try the 4 ohm tap of the Paramount to keep the damping factor as high as possible, as long as that gave enough voltage swing to drive them to useful levels. As an aside the best I have heard the LCD-2 was with a Benchmark Dac One. However I don't like the DAC part of the DAC One so I don't really see that as the ultimate solution. If we get the time we may address the notion of building a special amp specifically for the LCD-2, unless my own headphone design pans out and I like it better.

 

[Frihed89]

Thanks Doc,

So I guess I should talk with Mike when I am ready to talk turkey.  Are you going to be at RMAF in October?

I will ask you about the LCD-2s later, after May.

I guess that's all or now.

 

[Doc B]

I will be at RMAF (thanks for reminding me that I need to call Marjorie). I think this may be the first time since 2004 that Bottlehead will have its own room there. Have to see who all wants our gear in their rooms...

 

[Paul Joppa]

Doc B answered most of these; I'll just touch on a few output transformer points.

The power transformer is a proprietary design with several features specific to this amplifier. Among other things, it operates at unusually low flux density, and the windings are arranged to shield each other, and to shield the internal voltages from the external circuit. These features were chosen to reduce electric, magnetic, and mechanical sources of hum, buzz, and power line noise.

The Magnequest page shows upgrade kits, consisting of two output transformers and two plate chokes. The Paramour kits include the BH-6 plate choke; the Paramount kits include the larger BH-7 choke at the cost of $50 more. Both have the BH-5 output transformer, and you have a choice of core materials. The BH-6 is rated 50mA, which is fine unless your power line is too high a voltage - above 240v (or 120v if you have that power transformer). A high line voltage will also increase the 2A3 current, in which case I would get the BH-7s. But consult with Mike at Magnequest about getting BH-7 chokes with a slightly smaller air gap; it might be worthwhile and he is sometimes accommodating about such things.

There is one other option. You could get a full TFA-2004 - like Doc B, I prefer the Permalloy core. This is a true classic transformer design, possibly the best I have ever heard - the TFA-2004Jr and the BH-5 use the same coil geometry on a smaller lamination stack. It must go on top of the chassis; it just fits but you would have to drill appropriate mounting holes and an entry hole for the leads. The thicker core gives greater magnetic headroom (cleaner, deeper bass - in theory at least). Personally, I think that is not cost-effective unless you are using the 300B, but you asked for full disclosure! The larger core might reduce the treble extension in theory, but I haven't made enough detailed measurements to be sure of that since the insulation materials are different.

I have not done any direct comparisons of silver vs. copper wire so I can't comment. It would surprise me greatly if any such differences were more than a tiny fraction of the core material difference - but I've been surprised before and expect I will be again.  :^)

The BH-5 and Jr coils have taps at 8 and 16 ohms; the full-size TFA-2004 also has a 4-ohm tap. The stock Paramount transformer can be wired for 4, 8, or 16 ohms but they are not taps - the secondaries are connected differently to obtain these impedances, either with soldered connections or with a 2-pole 3-throw switch (not supplied with the kit).

 

[Frihed89]

Thanks Doc and Paul.  There's a good chance I can make RMAF this year.  I prefer to listen before I buy and I have several 2A3 amps on my list.